Sustainable Fisheries through Sustaining Fish Habitat

------· -- - Department of Primary Industries and Energy Bureau of Resource Sciences

Proceedings Sustainable Fisheries through Sustaining Fish Habitat Australian Society for Fish Biology Workshop

Victor Harbor, SA 12-13 August 1992

Editor: D.A. Hancock

Australian Government Publishing Service Canberra © Commonwealth of Australia1993 ISSN 1032-2469 ISBN O 644 29632 I

This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from the Australian Government Publishing Service. Requests and inquiries concerningreproduction and rights should be addressed to the Manager, Commonwealth Information Services, Australian GovernmentPublishing Service, GPO Box 84, Canberra ACT 260 I.

Preferredway to cite this publication: Hancock, D.A. (ed.)1993, Sustainable Fisheries through Sustaining Fish Habitat, Australian Society for Fish Biology Workshop, Victor Harbor, SA, 12-13 August, Bureau of Resource Sciences Proceedings, AGPS, Canberra.

The Bureau of Resource Sciences is a professionallyindependent Bureau in the Department of Primary Industries and Energy. It was formedin October1992 from the existing Bureau of Rural Resources and the resource assessment branches of the former Bureau of Mineral Resources.

The Bureau's role is to support the sustainable development of Australia's agricultural, mineral, petroleum, forestry and fisheries industries by providing scientific and technical advice to government, industry and the community.

Bureau of Resource Sciences PO Box Ell Queen Victoria Terrace Parkes ACT 2600

Printed for AGPS by Pirie Printers Pty Limited, Fyshwick, A.C.T. FOREWORD

J.G. Pepperell President Australian Society for Fish Biology

This workshop, entitled "Sustainable Fisheries I believe that these workshops, and their through Sustaining Fish Habitat", continues the published Proceedings, are now recognised as Australian Society for Fish Biology's workshop benchmarks in the development of fish and series and its established tradition of bringing fisheries science in Australia. The present vol­ together the country's leading experts to freely ume is no exception. discuss specific fish and fishery themes of na­ The fisheries working group of the Federal tional importance. Past workshops have pre­ Government's Ecologically Sustainable Devel­ ceded the Society's Annual Conferences, and opment strategy noted that ... "management has began with a meeting on "Australian Threat­ to establish operating frameworks which em­ ened Fishes" in Melbourne in 1985. Themes brace both economic and environmental factors since then have covered diverse topics: "Ad­ ... (which) must ensure prudent management vances in Aquaculture", "The Use of By-catch which determines and implements the neces­ Resources in Australia", "Scientific Advice for sary arrangements and controls to safeguard the Managers: Getting the Message Across", "Tag­ resource and the environment in concert with ging - Solution or Problem?", "Introduced and sound development of the commercial indus­ Translocated Fishes and their Ecological Ef­ try". (To this I would add the recreational fish­ fects", "Legal Sizes and their use in Fisheries ing industry). In fact, the first nine of the working Management", "The Measurement of Age and group's recommendations relate to concerns for Growth in Fish and Shellfish", "Larval Biol­ ecosystems and fish habitat. ogy", and "Recruitment Processes". The primary aims of the Society's success­ Since 1988, the workshops have been gen­ ful application for funding to FRDC were: To erously supported by the Fishing Industry Re­ identify national fish habitat research needs, search and Development Council (now the and to clarify management's needs to fisheries Fisheries Research and Development Corpora­ scientists. The workshop attracted a record at­ tion, FRDC). This support has ensured the at­ tendance, encouraging lively and enthusiastic tendance of overseas experts at the workshops, debate, and I am confident that all present would and has allowed professional editorial treatment agree that those goals were met. of the published Proceedings. The Bureau of Rural Resources (now, Bureau of Resource Sci­ The keynote speaker at the workshop was ences, BRS) has also been most generous in Stan Moberly, a past President of the American contributing substantially to the costs of publi­ Fisheries Society, and formerly Director of the cation of Proceedings. Alaska Fisheries Department. I am sure you will

Bureau of Resource Sciences Proceedings iii find his address in these proceedings both stimu­ lating and enlightening, and those present will remember his infectious zeal in relaying his experiences and concerns about fish habitat. In a letter to the Society after his returnto the U.S. he stated: "In my opinion, the health of a nation and the quality of lifeit offers its citizens can be judged by the health of its aquatic ecosystems." I'm sure a large majority of us would agree. During the workshop, an important new committee on Fish Habitat was formed. Con­ vened by Jenny Burchmore, this committee will play an important role in habitat protection and education in the future. Rob Lewis swung the resources of the South Australian Department of Fisheries behind the workshop and conference, and his assistance at all levels is greatly appreciated. The workshop organising committee, convened by Bairy Bmce, did a magnificent job, so many thanks also to him, together with Ene-Mai Oks, Keith Jones, Mervi Kangas, Gary Jackson and Kate Messner. I also wish to acknowledge the hard work of the editor, Don Hancock, and his persistence in gently prodding presenters, rapporteurs (and myself)to complete and forwardmanuscripts so that these Proceedings could be published at all, let alone, on time. He has been ably assisted by Gregg Berry of BRS. This volume continues the tradition set by previous workshops, and furthers the high stand­ ards which they have achieved. I commend it to you.

iv Bureau of Resource Sciences Proceedings Contents

Foreword J.G. Pepperell ...... iii

SESSION 1: Introduction Keynote Address: Habitat is Where It's At! "It's More Fun to Fight over More Fish than Less Fish" S.J. Moberly ...... 3 Discussion of Keynote Address Recorded by J.P. Glaister ...... 14

SESSION 2: A Manager's View of Fish Habitat Chairperson's Introduction R.K. Lewis ...... 19 An Ecosystem-based Approach to Marine Fisheries Management K.S. Edyvane ...... 21 Estuarine Issues from the Manager's Viewpoint R.H. Winstanley ...... 28 Freshwater Habitat Protection-A Manager's Perspective P.D. Jackson ...... 32 Discussion of Session 2 Recorded by G.M. Newton ...... 35

SESSION 3: Organisms and Environmental Relationships I-Case Studies Chairperson's Introduction P.C. Gehrke ...... 41 Maintain or Modify-Alternative Views of Managing Critical Fisheries Habitat I.R. Poiner, N.R. Loneragan and C.A. Conacher ...... 43 Rehabilitation, Mitigation and Restoration of Fish Habitat in Regulated Rivers S. Swales ...... 49 A Habitat Fit for Fish-An Aim ofBiomanipulation? M.T. Bales ...... 57 Enhancement of Estuarine Habitats in Association with Development R.M. Morton ...... 64 Discussion of Session 3 Recorded by G.A. Thorncraft ...... 70

Bureau of Resource Sciences Proceedings V SESSION 4: Organisms and Environmental Relationships II-Key Variables and Broad Based Issues Chairperson's Introduction: Key Factors Linking Fish and Their Habitat B.E. Pierce ...... 75 Freshwater Fish Habitats: Key Factors and Methods to Determine Them J.D. Koehn ...... 77 Defining Key Factors Relating Marine Fishes and Their Habitats P.C. Young and J.P. Glaister ...... 84 Defining Key Factors Relating Fish Populations in Estuaries and Their Habitats N.R. Loneragan ...... 95 Discussion of Session 4 Recorded by M.I. Kangas ...... 106 General Discussion-Day 1 Recorded by D.C. Smith ...... 109

SESSION 5: Impact of Human Activities on Habitat and Fisheries Chairperson's Introduction C.M. MacDonald ...... 115 Habitat Changes and Declines of Freshwater Fish in Australia: What is the Evidence and Do We Need More? M. Mallen-Cooper ...... 118 Ecological Basis for Parallel Declines in Seagrass Habitat and Catches of Commercial Fish in WesternPort Bay, Victoria G.P. Jenkins, GJ. Edgar, H.M.A. May and C. Shaw ...... 124 Effects of Trawling on the Marine Habitat on the North West Shelf of Australia and Implications for Sustainable Fisheries Management K.J. Sainsbury, R.A. Campbell and A.W. Whitelaw ...... 137 Discussion of Session 5 Recorded by P.C. Coutin ...... 146

SESSION 6: Alternative Uses (Economic, Social and Political)-Key Values Chairperson's Introduction R.E. Reichelt ...... 155 Maximising the Potential for Both Sustainable Fisheries and Alternative Uses of Fish Habitat through Marine Harvest Refugia D.A. Pollard...... 156 Alternative Uses of Aquatic Habitats: An Economic Perspective A.J. Staniford ...... 159

vi Bureau of Resource Sciences Proceedings Discussion of Session 6 Recorded by J. Robertson ...... 165

SESSION 7: Management (Amelioration, Enhancement, Conservation) Chairperson's Introduction B.A.Richardson ...... 171 The Management of Marine Habitat R.N. O'Boyle ...... 174 Management of the Estuarine Habitat J. Burchn1ore ...... 184 Managing Freshwater Fish Habitat W. Fulton ...... 188 Discussion of Session 7 Recorded by D.A. Pollard ...... 191

GENERAL DISCUSSION Recorded by P.R. Last ...... 199

SUMMING UP S.J. Moberly ...... 209

APPENDIXES Appendix 1:Australia's Threatened Fishes 1992 Listing-Australian Society for Fish Biology PD. Jackson,J.D. Koehn and R. Wager ...... 213

Appendix 2: Workshop Program ...... 228

Appendix 3: List of Participants ...... 231

Bureau of Resource Sciences Proceedings vii SESSION 1

INTRODUCTION

Keynote address: S.J. Moberly Rapporteur: J.P. Glaister 2 Bureau of Resource Sciences Proceedings KEYNOTE ADDRESS: HABITAT IS WHERE IT'S AT! "It's more fun to fight over more fish than less fish"

S.J. Moberly NorthwestMarine Technology Inc. POBox99488 Seattle WA 98199-0488

Abstract formed a coalition: F.I.S.H.,Fishermen Involved in Saving Habitat, a Coalitionforthe Conserva­ Coastal resources are under siege. Our fisher­ tion of Aquatic Habitat. F.l.S.H. has a single ies face many threats, and experience at least mission; to elevate interest in the highest levels the following problems; habitat loss, pollution, of governmentto the need for a national policy ove,fishing,overcapitalization, inadequate fund­ to protect, conserve, enhance, and restore the ingfor management and research, bycatch waste, quality and diversity of fisheries habitat through­ depleted stocks and increased demand. out the nation. The American Fisheries Society The greatest threat to a nation's fishery was responsible for calling the first meeting, resource is not overharvesting or runaway com­ bringing the leaders of the nation's fishery petition. It is the loss of habitat, and pollution! community together, which led to the formation of the Coalition. Loss of habitat compromises the ability to maintain sustainable long term yields.If a coun­ Our professional society has a special role try truly values itsfisheries, then habitat must be to play; a leadership role as "honest broker" in the centrepiece of the portfolio.Habitat is what advancing fishery science and management. provides the benefits. Loss of habitat will even­ The conservation of aquatic resources requires tually doom the fishery aspirations of future fishery professionals to be political activists for generations. the resource as well as good scientists. Nations concerned about their fisheries My duties today are to set the tone of the resources, will have in place, national habitat workshop and to arouse a sense of unity and conservation strategies, action agendas, and enthusiasm. What I am about to suggest is an plans for implementation. Governments must additional role forthe fisheriesprofessional. A allocate sufficientrevenues to assure that habi­ role most of us are not enthused about. A role tat conservation objectives can be achieved. some of you downright oppose. I will make a case that we must be proactive for sustainable The duty of all fisheries professionals is to fisheries and healthy aquatic ecosystems. We take an active, leadership role in the develop­ cannot sit idly by conducting our research, en­ ment of "The Fisheries Agenda." gaged in lofty intellectual exercises, while habi­ In the United States,fishery leaders, react­ tat disappears. Activism is not for everyone. But ing to the serious loss and continuing degrada­ our profession must speak out. Our challenge is tion of habitat essential for fish production, to maintain our traditional role of providing

Bureau of Resource Sciences Proceedings 3 scientific information while aggressively pre­ passed twenty years ago. In the Act, our Con­ senting objective, focused scientific analysis to gress stated that it shall be a national policy, to policy makers. preserve, protect, develop with proper environ­ mental safeguards, and where possible, restore My definition of fish habitat is fairly sim­ and enhance, the resources of the Nation' s coastal plistic; habitat is anywhere fish are found. We zone forthis and succeeding generations. But, all define habitat in different ways. But to keep saying it does not make it happen. Our govern­ it simple, at least for today: habitat is anywhere ment has not followed through with adequate fish live. The quality and quantity of habitat funding. must be sufficient to sustain healthy aquatic ecosystems. While the problems to be solved in the coastal zone are staggering, none are as Our inland and coastal aquatic resources challenging as habitat conservation. In the U.S. are under siege from careless and unwise land­ our coastal states and territories responded to use activities. Our fisheries face many threats in the new Coastal Zone Management Act by addition to habitat loss and pollution, including developing comprehensive management plans. overfishing, inadequate management and re­ To comply with the provisions of the Act, each search, bycatch problems, and waste. coastal state plan was required to include But, the greatest threat to the resource is not provision forthe "protection ofnatural resources, overharvesting or competition among fisher­ including wetlands, floodplains, estuaries, men; it is the loss of habitat, and pollution! beaches, dunes, maritime forests, banfor islands, Human population growth, ignorance, poverty, coral reefs, and fish and wildlifeand their habitat, irresponsible land use activities and develop­ within the coastal zone". mental practices have endangered water re­ There has been significant progress since sources and destroyed habitat essential for the Act was passed twenty years ago but, during sustainable aquatic resources. the past decade coastal states have witnessed Habitat loss compromises and forever de­ dramatic growth as the American population stroys our ability to produce sustainable ben­ shifts from the interior to the coastal zone. By efits. If any country considers its aquatic the end of this century, seventy per cent of the resources an asset and values its fisheries, then U.S. population will Iive within 50 miles of the habitat has to be a priority. Loss of habitat ocean. These coastal lands are not only our most bankrupts the fisheries aspirations of future valuable lands but our most fragile. This popu­ generations. lation shift will have a destructive impact unless steps are taken to protect valuable coastal re­ All nations, concerned for their fisheries sources while accommodating population resources, must develop national habitat con­ growth. servation strategies, action agendas, and plans Polls over the past 20 years have demon­ for implementation. Most important, govern­ ments must allocate sufficientjimdsto accom­ strated that Americans want increased environ­ plish the job. mental protection. But these same people participate in one of the industrialized world's Talk is not action, and saying it does not most wasteful and polluting life styles. While result in improved habitat! The United States Americans "talk" a great game, our government President, during the Earth Summit discussions hasn't "backed up the talk" with sufficient money noted that the U.S. has a set of environmental to implement the laws that have been passed. laws second to none in their stringency. Our Habitat conservation is simply not yet a high federal Coastal Zone Management Act was priority.

4 Bureau of Resource Sciences Proceedings Our budget deficit is talked about daily and Our knowledge of fish and shellfish ecology is it continues to soar out of sight. What is tragic substantial and our understanding of the habitat is that the environmental cost of the goods and interaction is rapidly increasing, but we have services we produce is not even accounted for failed to effectively communicate our knowl­ in this deficit. We have a "frontiermentality," edge to the fishermen and the public in general. which assumes inexhaustible resources and Our scientific findings lay dormant in agency black holes in which to dump our waste. Our reports, peer-reviewed journals, and fieldnotes. leaders during most of the 1980's honestly felt We spend most of our time talking to one that the American west was still open; "a fron­ another. Most of our literature cannot be under­ tier," and whoever arrived first could claim it. stood by policy makers. Do we really expect the But natural resources are capital; second only press or the general public to plough through to a nation's human resources in value, and a scientific journals seeking answers to habitat nation's accounting system must include envi­ problems? ronmental costs. Our Congressmen and Sena­ Fishermen should be in the "front lines," tors are devoted to re-election, and investments helping to defendagainst lost habitat. Curbing now in long term solutions that won't manifest the loss of habitat will require a change in the foryears does not get you re-elected tomorrow. behavioral characteristics of fishermen. It will We can blame those who destroy our habi­ require the scientific community to communi­ tat while developing our coast and river basins cate with those outside our ranks. Politicians and we can blame those in Congress that fail to will have to do more than pledge concern and fundlegislative solutions, but we can and should then fail to fund appropriate action. Conserving also blame the fishermen. Fishermen may be habitat has to be our highest priority. The best characterized as greedy, wasteful, independ­ and most effective way to communicate what ent, defiant and firm in their belief that it's not we know is through our professional society. I only their privilege to fish, its their God-given believe our professional society is the best vehi­ right to fish! But consider this for a moment. cle to help adjust national and international They do act rationally to the rules that govern priorities regarding aquatic habitat. them. The reason they don't exhibit equity­ In the U.S. we have yet another obstacle to ownership-behavior is because they don't own overcome; ifwe were trying to doom our aquatic anything! We all know that public ownership resources to a long, slow and sure death, we resources are particularly vulnerable to over­ would create a governmental process similar to spending and this is particularly true with our the way it is now. We have to find ways to work fisheries. around the inefficiencies of government. The United Nations estimated in 1989 that North America is occupied by three coun­ the areas from the coastline to the continental tries. Much of the border between Mexico and shelf produce 97 per cent of the world's fish. the United States is defined by a line drawn The United States estimates that approximately down the middle of the Rio Grande river. To the 7 5 per cent of the nation's commercial fishery north, the U.S. and Canada share the Great landings (both fish and shellfish) are comprised Lakes and draw a line down the middle of the St. of estuarine-dependent species. Fishermen are Lawrence river to define their eastern jurisdic­ mostly ignorant about the connection between tion. In Southeast Alaska the international coastal habitats and the fish they pursue. boundary places watersheds in British Colum­ If fishermen do not understand and appre­ bia and river mouths in Alaska. Our federal ciate the relationship between the habitat and government and the states have drawn an imagi­ the fish and shellfish they harvest, don't be nary line three miles offshore to define surprised. Part of the blame has to fall on us. jurisdictional responsibilities.

Bureau of Resource Sciences Proceedings 5 As the United States was gradually settled ies management is ignored. Who speaks on over the last two hundred years, the states se­ behalf of the rivers or estuaries? Most of our lected natural barriers as their boundaries. This states don't have an instream flow allocation for is especially true in the Mississippi River basin. fish and wildlife. In dry years it is not unusual to Many of the states in the basin claim responsi­ discover that water allocations exceed t� e total bility to the mid point of a river that defines its capacity of the river. The scientific com111unity border. As a consequence twenty-eight states knows that estuaries are users of freshwater. share responsibility for the resources in the Estuaries require the right amount of water at the Mississippi River watershed. In most cases the right time or they die. But neither fishermen nor states and the federal government have made policy makers fully appreciate this inescapable strong statements about their commitment to scientific fact. It is our duty to educate and curb the loss of habitat and prevent pollution, motivate them. but little is accomplished because the institu­ In the U.S. the statistics are grim! The most tional arrangements are so varied, so complex, recent National Marine Fisheries Service as­ and so illogical. sessment on the status of our coastal fisheries We use the Mississippi River forjust about reveals in part that: everything and anything man can imagine to fourteenstocks, species or species groups haul up, float down, pump out, and dump in. are considered to be overexploited; People who monitor these sort of activities estimate that there is a "dead-zone", approxi­ nearly 1/3 of all species and stocks for mately a million hectares in size, off the mouth which informationis available have expe­ of the Mississippi River. Health statistics reveal rienced population declines since 1977; that human cancer rates are much higher than there is insufficient information on the sta­ the national average forthose people living in tus of another 29% of U.S. fisheries; and the lower reaches of the river. Even so, the Mississippi River isn't as polluted as many of ten of the 14 overexploiteu stocks would the world's rivers. require 5 to 10 years to recover if fishing stopped all together, yet fishing continues If our mish-mash of jurisdictions isn't in eight of these ten fisheries. enough to contend with, our federal government divides the responsibility forfisheries and habi­ Despite a stated commitment to habitat tat between 37 agencies with 9 executive level conservation, Fishery Management Councils departments. It would be difficult to design a spend most of their time setting catch levels that more problematic management scheme. But are more attuned to the economic needs of the even worse, the federal government as well as fishermen than to long-term conservation of the many of the states have organized themselves stocks. The intent of the Magnuson Act, the U.S. by constituent group (recreational, commercial, federal law which guides management of the aquaculture) or by salinity (freshwater vs ma­ nation's living marine resources, will be worth­ rine). Fourteen of our coastal states have at least less without habitat protection. two separate fisheries management agencies Only recently has the U.S. federal govern­ and in some cases management of aquaculture is ment admitted that overharvest and loss of habi­ the responsibility of a third agency. In many tat are the causes for the collapse of many states the responsibility for water quality and stocks. Also being recognized are state and pollution can be found in an additional one or federal subsidies that stimulate activities that two agencies. destroy habitat. This is especially true of riparian Governments squabble over "states rights" habitat on federal lands in the western United vs "federalrights" while what's right for fisher- States where water resources are limited.

6 Bureau of Resource Sciences Proceedings In addition to overharvesting, we have a Habitat and water quality essential to fish in huge problem with bycatch and waste. The Alaska are virtually intact. Not because the shrimp fishery in the Gulf of Mexico takes, in Alaskans are better land managers but because addition to shrimp, 115 species of fin fish and the ventures into farming and other agricultural average offshore shrimp vessel takes ten pounds activities by both private business and the gov­ offinfish for each pound of shrimp. This produces ernment, have mostly been failures, although a 90 per cent bycatch totalling just under one­ mining employing old fashioned techniques, half million metric tons (1.1 billion pounds) per and other extractive activities, continue to be a year. The bycatch, most of which is dead, is problem. Alaska's population is slightly over returnedto the water. This isn't just an American 550,000 with half the citizens living in Anchor­ problem either. According to the United Nations age. This small number of people hasn't war­ more than 5 million metric tons of sea life were ranted the building of enormous hydroelectric discarded in the world last year; most of it was dams. So, many habitat-destroying activities dead. While fish stocks are being depleted and have either failed or just not taken place because we are suffering loss of habitat and polluting our of special conditions. But as the state's popula­ waters, our fishing industry continues to promote tion increases, unless priorities change, Alaska even greater seafood consumption. will no doubt follow the path that other states have taken and find their fish producing capa­ Fishing in the U.S. is the second most bilities diminished. popular form of recreation. Our recreational fishing industry continues to promote fishing When I arrived in Alaska in 1970 I was and the intention is to displace commercial users overwhelmed by the natural beauty, forested to meet their demands. The commercial indus­ mountains and hundreds of miles of streams and try expects to meet additional consumer de­ rivers! Rivers you could take a drink from.Was mand with products provided by aquaculture. I in fisheries biologist heaven? Our seafood industry launched a promotion last North American waters are reputed to pro­ year calling for an increase in domestic con­ duce or possess approximately twelve to fifteen sumption of 30 per cent. Their battle cry is 20 by per cent of the world's living marine resources. 2000 (20 pounds by the year 2000). A drop in The waters off Alaska contribute about seventy seafood consumption in the U.S. this year is to eighty per cent of this amount which means being attributed to consumer concern about the that Alaska has about ten per cent of the world's safety of eating seafood. Much of our coastline living marine resources lying off its shores. is polluted. What is wonderful and astounding is that virtu­ In two hundred years we have managed to ally all the habitat responsible forthis produc­ destroy over half of our wetlands, and our fish­ tion capability is intact. eries generally have never been in worse condi­ In 1973 and 1974 the commercial harvest tion. But plentiful, high quality functioning of salmon in Alaska hit an all time low of about habitat doesn't necessarily mean healthy fisher­ 22 million fish. This was a lot of fish to a ies. The value of a fishery can be driven down­ biologist from the flat lands of middle America. ward by unthinking political interferenceand an The harvest had been dropping over the years industry without vision. from a previous high period in the 1930's. Early in my career I decided that the only Harvest levels exceeded 100 million fish in way I was ever going to see Alaska was to work several years with the peak of 126.4 million fish there. "Fish" was the number one crop in Alaska taken in 1936. These low harvests were attrib­ and fishing was the state's largest private uted to overfishing and less than average envi­ employer. ronmental conditions.

Bureau of Resource Sciences Proceedings 7 The low harvest in the early 1970's pro­ A second example involving an offshore vided the incentive for a very ambitious reha­ fishery in the North Pacific and Bering Sea is bilitation and enhancement effort. I started with the Pacific halibut fishery. The native people the program in 1975 as a research biologist and living along the Pacific coast had been fishing was Director from 1982 until I retired in 1987. halibut for several thousand years. Commercial The program started in 1971 and was put on a fishing was first recorded in 1887 off the coast "fast track." By the start of the 1980's the of Queen Charlotte Islands, British Columbia. program was in full swing, employing all tac­ By 19 I 5 the halibut stocks off North America tics; clearing streams of logging debris, build­ were fully exploited. Reduction in catch per ing fish ladders, and constructing hatcheries of effort as the stocks were heavily fished caused every size. We worked hand-in-hand with a demands from the fishermen for the govern­ reformed management program that allowed ments to take control of the fishery and assess adequate escapement of fish to theirnatal streams the condition of the stocks. In 1923, a joint to spawn. treaty between Canada and the United States established the International Pacific Halibut The program was very successful and dur­ Commission and over the years the two coun­ ing the decade of the l 980's, fish production tries have renegotiated the treaty, gradually doubled. At the same time Alaska lost approxi­ giving the Commission more authority to regu­ mately 10 per cent of its world market share. late the fishery. Most of this loss was due to farmed salmon which could satisfy the fresh fish markets year Biologically this resource is managed fairly round. Salmon production, as a result of the well. But the Commission controls only sev­ enhancement effort and better management enty per cent of the harvest. Bycatch of halibut methods, has now pushed the harvest to all time in other fisheries, mainly the U.S. groundfish highs. In 1980 the harvest exceeded 100 million fleet, and waste, account for most of the other 30 fish and the mean harvest for the past twelve per cent which isn't under the Commission's years has been 130.5 million. A new historic control. When setting the fishing mortality lev­ high harvest was reached last year with 188 els, the Commission takes this loss offthe top million salmon harvested. In the latter part of the and allocates the remainder to the fishery. Large 1980's, Alaskan lawmakers passed legislation bycatch coupled with larger than appropriate rejecting salmon farming as a private business. harvest caused the stocks to decline to an all This means Alaska will go head-to-head with time low in the mid-1970's. Gradually, a reduc­ the world fresh fish market for about three tion in bycatch combined with lower harvest months and then turncustomers away, sending and favorable environmental conditions allowed them to other producers that can supply fresh the stocks to rebuild to a level which permitted fish on a year round basis. Unless the Alaskan historically high removals in the latter part of fishing industry finds new markets and/or new the 1980's. product form for its canned and frozen salmon, The number of fishermen and fishing the benefits to be derived from its enhancement vessels participating in the fishery are not under efforts will never be realized. the Commission's control either. In the U.S. the Having habitat and productive fisheries social and economic aspects of the fishery are therefore doesn't mean that all is well socially the responsibility of the North Pacific and economically. But the Alaskans will have Management Council, and their actions or time to search for solution� that meet their needs inaction have almost destroyed the value of the and extract full value from the incredible resource fishery. The U.S. halibut fishery is managed as they are blessed with. They have this ·option an "Olympic event." Open access has allowed only because the habitat hasn't been destroyed. a larger than necessary fleet to develop. Since

8 Bureau of Resource Sciences Proceedings 1975 the fleet has swelled in size from 2,424 conventional thought inhibits implementation vessels to 4,222 vessels in 1990. To maintain of new methodologies that would maximize the harvest limits the fishing season consists of a resource, and governmentis not providing the few 24-hourfishing periodsoften with individual leadership necessary to solve the problem. vessel catch limits imposed. The short seasons If your country or mine elects to preserve cause safety and enforcement problems, and and manage habitat, it is an investment decision. more fishing gear is set that can be recovered. On the other hand if government allows The excess gear with hooked fish is often indiscriminate destructive activities it is deciding abandoned, wasting an estimated 1500 mt of not to make this investment. Open access and halibut. The short seasons do not allow sufficient Olympic-style fisheries are not the result of time to dress the fish promptly, and the product random decision making. Governmentis making has declined in quality while the cost of an implicit decision to overfish and to ignore the participating in the fishery and the processing waste and social disruption these decisions cause. costs have increased to a level that almost exceed Governmentis ignoring the dividends that could the value of the harvest. The bottom line is that and should accrue to future generations. The consumers pay a higher price for a product that way governments are organized makes is lower in quality. managing fisheries, conserving habitat and The Canadian fishery, on the other hand, maintaining water quality extremely difficult. has been closed to entry since 1979 and the fleet But it was the "rule making process" that created has been reduced to 435 vessels. The Canadians these circumstances and it is only the rule making adopted individual seasonal vessel quotas in process that can lead to change for the better. 1991 and the quotas can be marketed in 1993. Our fishery resources provide food, enjoyment This will consolidate the fleet further and produce and employment; they are a litmus test for a better product for the consumer. healthy aquatic ecosystems and this dictates quality of life, the value of which goes far Fisheries management usually fails because beyond just dollars and cents. of the lack of adequate stock assessment due to insufficient or poor data and bad science. Couple Responsibility for change rests, in large this shortfall in performance with habitat loss part with you and me. Ultimately the responsi­ and pollution, and the outcome is predictable. bility rests with our elected representatives. We Fisheries management can also fail because of have a responsibility to see that our elected the wrong type of political interference. If representatives and the public have the opportu­ government fails to maximize, on a long term nity to learnthe truth through communication in basis, the social and economic benefits of the a form they can understand. This makes us an fishery, full value of the resource will never be essential part of the rule making process. realized. The ingredients forsuccessful fisheries I have no doubt we can do the job if it is a are good science, good management practices, priority. In the U.S., we know how to do good adequate habitat conservation and the right science, we have strong mandates from our regulations, together with enlightened political citizens, and the politicians have responded by supp01t and the funding necessary to do the job. enacting appropriate legislation. But the The Alaskan salmon fishery and the North legislation is not enforced nor is 5ufficient Pacific halibut fishery are two examples of funding provided to do the job right. What we situations where the science is good and habitat lack is the will to place enough value on these loss and pollution are not the problem. Full resources to adjust our priorities, and hold people value fromthese resources is not realized because accountable.

Bureau of Resource Sciences Proceedings 9 Just last year we watched the U.S. President the Society to influence environmental policy persuade most of the rest of the world that it was and public education. Our members were tired a priority to deal with Iraq. Joined by our allies, of seeing the resources they worked to conserve we sent half a million of our citizens, half way continue to diminish. I was an officer in the around the world to fight a war for reasons not Society and when we asked who was willing to fully understood by the majority of our citizens. help, few stepped forward. Activism can be Government responseto a problem doesn't come scary! What our members were suggesting was any stronger. The President said it was the right that the Society should be the activist and not the thing to do and the country followed. Taking individual members. So we did what any good care of our aquatic habitat is the right thing to do society of scientists would do and we conducted and if our elected leaders come to believe this, another survey. The second survey confirmed it'll become a national priority. If we can put a the first, so we conducted a third survey; again man on the moon why can't we bring continuing with the same outcome. loss of habitat to a screeching halt? So we had our mandate from the members It is my strong belief that fisheries profes­ and we set off to be activists. But we were not sionals must play an aggressive role in policy very sure what needed to be activated. So again, development. We must help influence those like any scientific society worth its salt, we set decision processes which affect the health and about to study the matter. We decided to "study" viability of our aquatic resources and which the federal government.After all, we were upset provide for the protection of habitat. Like many with the fragmentationof fisheries research and in this profession, I didn't come to this convic­ management among federal agencies, and the tion naturally or early in my career. I just wanted severe reductions in funding,annually proposed to study fish. But as the years passed, I couldn't in the President's budget for the National Ma­ help but notice that fishing wasn't as good as it rine Fisheries Service. used to be. Fishermen complained more and The Society's President appointed a 20- consumers were more apprehensive about the member committee of senior fishery scientists safetyof eating seafood. Our waters were dirtier and managers having extensive and varied ex­ and more contaminated and in many places even perience in federal, regional, and state fishery though fishing was good, you didn't dare eat the affairs. The President charged the Committee to fish. When I finally faced up to the fact that I review the current distribution of major fishery personally could do something about this situa­ research and management authority among fed­ tion, I became an activist. I used my professional eral agencies; the rationale for the current pat­ society as my vehicle. tern of organization and services; and to explore I believe the fisheries professional occupies various alternatives for improving federal or­ a special niche; acting as a catalyst and "honest ganization and operation for fishery conserva­ broker", a voice that can speak on behalf of the tion and management. Finally we were to resource. If we don't speak who will? I now formulate a proposal for reorganization of the believe we inherit this role when we select this U.S. federal government'srole in the nation's profession; it goes with the territory and its our fishery affairs. We called the committee the responsibility. And while some of my colleagues Federal Fisheries Responsibility Committee. don't believe vacant niches are possible, I con­ I joined the Committee because I was pass­ tend in this case, that when we fail to occupy this ing through the officers'chairs and if the Com­ niche, there is no one else to fill the vacancy. mittee completed its work during my term as In the early l 980's the American Fisheries Society President, it would become my respon­ Society conducted a member survey and discov­ sibility for implementing the recommendations. ered that members favoured more activism by My foresight proved correct. The Committee

10 Bureau of Resource Sciences Proceedings completed its work in 1987 and the Society failed to look upon each other as allies. In fact, Executive Committee charged me, as incoming many of the organizations that were sitting President, to implement the Committee's rec­ about the table that August were more accus­ ommendations. tomed to competing with each other for harvest quota. I couldn't very well order another survey nor appoint another committee and I had my We quickly reached agreement on one is­ orders. I just didn't know how to go about sue. We concluded it was more fun to fightover getting the job done. In the past, when difficult more fish than less fish. Secondly, everyone and contentious matters faced the Society it was agreed that habitat was the single most impor­ a common and accepted tactic to study the tant issue. We agreed that a nation-wide aquatic matter by appointing another committee. At education program was the only long-term solu­ least it would come due on someone else's shift. tion if we intended to change the attitude of an But my choices were limited and besides I was entire nation. There was no consensus on any impatient! We had just completed a two-year other issue. The moment a species of fish was extensive analysis of fishery problems by an mentioned or a type of gear or a geographical unusually experienced professional group. The location, everyone got into small camps and study was the best available comparative as­ were either intensely interested ornot interested sessment of fishery-related roles offederal gov­ at all. We agreed to work on those issues for ernment agencies. The study offered specific which there was a unanimous consensus. recommendations for improving the integration and effectiveness of federal fishery manage­ The Society was the catalyst for this first ment authority and responsibility. This was good gathering of the F.I.S.H. coalition (Fishermen stuff.I had the support of the Society's govern­ Involved in Saving Habitat). F.I.S.H. would be ing body and I was bound and determined to do a nationwide coalition consisting of groups and something. I just didn't know what. But, to individuals representing the interests and con­ make things happen, you have to start some­ cernsof sport fishing, commercial fishing, con­ where. servation organizations, fishery scientists, fishery managers, fish processors and distribu­ I procrastinated for several months and tors and others. The charter members adopted a finally it dawned on me. If we expected to see single mission; to elevate to the highest levels of real change in how our government managed governmentconscience the need fora national our fishery, we were going to need all the help policy to protect, conserve, enhance and restore we could find. I started contacting all the other the quality and diversity of fisheries habitat organizations in the fisheries community and throughout the nation. We intended to see that we compared notes. I called all the national this goal became a priority with our govern­ conservation and environmental organizations; ment. There were no illusions about how long the commercial and recreational fishing organi­ this would take. It would be a forever job. zations; the media; and several individuals that Constant vigilance would be necessary to pre­ I knew were interested in better fisheries man­ vent what success we achieved over time from agement. When I felt there was sufficient sup­ being eroded. portto assemble a "critical mass" of these groups and individuals, I called them together in the Our goal for aquatic education was to teach first such meeting in August 1988. Everyone I our children how to think about conservation, invited attended! It seems that all our allies in not what to think. We envisioned a national this fish business were not only concerned but aquatic education program that would provide they were willing to help do something about it. every kid in America with knowledge m learn We had all been fighting the same fight but had their "environmental address." We wanted to

Bureau of Resource Sciences Proceedings 11 educate fishermen about the connection be­ "assessments" of the federal agencies most re­ tween habitat and harvest, so as to enlist them in sponsible for the nation's fish and wildlife our front line of defence. We wanted urban/ resources. These "assessments" were presented suburban planners to become informed of the by NFWF to Congress during budget delibera­ value of aquatic habitat so they could include tions. Through their effortsthe budgets of these maintenance and restoration provisions in their agencies were increasing each year and Con­ regulatory and permitting processes. gress was starting to realize this was a good investment. Our venture into the world of fish activism was launched but we were determined to do The North American Fisheries Leadership more. A broader role forthe Society required Workshop was held at Snowbird, Utah, in May greater visibility to the public. The only power 1991. The workshop product is our vision state­ the President of the Society has, is the power to ment for the future. We have shared this vision appoint members to committees and write let­ with every organization that might have an ters and call on important people on the Soci­ interest in the nation's aquatic resources. We ety's behalf. Using this "power" I challenged have requested their comments and we intend to the Fisheries Administrators Section to host an incorporate them into a N 011h American Fisher­ internationalworkshop, inviting all the fisheries ies Action Agenda. Following the workshop in leaders in North America, to create a vision for Utah, we commissioned Dr. John Harville, who our fishing future. Who better to start the ball had chaired the Federal Fisheries Responsibili­ rolling than the very people that are paid to ties Committee, to provide an analysis of all the spend most every day thinking about fish? major reviews of our national fisheries pro­ grams conducted in the past fifteen years. This The Administrator's Section agreed to host analysis documented many areas where there the meeting. Next we persuaded the U.S. Fish was a unanimity of consensus and where imme­ and Wildlife Service and the National Marine diate action could be taken to improve our Fisheries Service to co-host the workshop. This fisheries. This too has been widely distributed. provided the fiscal resources necessary for a successful meeting. Next we invited the Na­ In 1991 we agreed to create a Fisheries tional Fish and WildlifeFoundation (NFWF) to Action Network (FAN). This was our next step. join the effort. We suspected that the Founda­ Our purpose would be to support and enhance tion might be another "honest broker" and we efforts forinformed fisheries conservation, res­ could use a partner to assist in our efforts. For a toration and sustainable use. We would develop young organization they had great credibility an interactive process forprofessionals and user and influence with our Congress. groups to assist in the formulation of federal fisheries program direction. FAN is a (North The NFWF is a private, nonprofit organiza­ American) fisheries information communica­ tion established by the U.S. Congress in 1984. tion and advocacy process to inform and moti­ NFWF encourages and administers private sec­ vate conservation groups, the fishing industry tor contributions in support of the programs of and individuals. We reasoned that by providing the U.S. Fish and Wildlife Service, and pro­ scientifically sound fisheries information we motes other innovative public and private can help others accomplish their own fisheries partnerships to enhance the conservation and programs and goals. As part of our FAN effort management of the nation's fish, wildlifeand we have developed a review process with the plant resources. Its annual budget is around $20 National Fish and Wildlife Foundation staff, million, with $5 million allocated by Congress providing peer review for the 1993 fisheries and the remainder raised from private dona­ program proposals advanced by the National tions. The NFWF had been conducting Marine Fisheries Service, U.S. Fish and Wild-

12 Bureau of Resource Sciences Proceedings life Service, Bureau of Land Management, and Some professionals fear that we may com­ the U.S. Forest Service. We have prepared promise our reputation or our ability to do good congressional testimony forthe 1993 budget of science if we aggressively speak out. I don't these agencies. This past March the Society's agree but, is there an alternative?Our challenge Executive Committee established a Legislative is to maintain our traditional role of providing Committee to further direct the Society's input scientific information while presenting focused into the federalfisheries process. scientific analysis to policy makers. We must call attention to the value of these resources; Since colonial times the fish-producing must work to change the priorities and help our capability of the U.S. has been significantly governmentto lead. Most importantly our chil­ reduced. Watersheds have been altered and dren must learn their"environmental address," habitat lost through reasons familiar to us all. for regardless of our action or inaction, our Over the 122-year existence of the American children will inherit our accomplishments. Fisheries Society our profession has evolved from fish culturists to fish biologists to fish scientists and we now recognize and embrace a multi-disciplinary approach. And in the past fewyears we have learnedto be activists. The number of fisheries scientists in North America is at an all time high. At the same time, fish stocks have never been in worse condition, half of our wetlands are gone and habitat continues to be unacceptably altered and destroyed. Ob­ jectives for the nation's fisheries and aquatic ecosystems remain unfocused and largely unimplemented. Prevention of habitat loss is still not a priority with our government. Our numerous agencies are often at odds and we, as fisheries professionals, have been guilty of not communicating our knowledge to those most important to the decision-making process. The American Fisheries Society has rec­ ognized that there is a critical need to commu­ nicate scientifically-based fisheries conservation information to the public. The only basis for a rational fishery is good science. The very nature of our job places us in a special role; a special niche as the "keepers of the data base." The data we collect must be turnedinto useful information capable of being absorbed and acted upon by our decision makers. While the political process should not be allowed to shape our scientific conclusions, the benefit of our analysis must be reduced to a digestible form for otherwise we will be ignored.

Bureau of Resource Sciences Proceedings 13 DISCUSSION OF KEYNOTE ADDRESS

Recorded by J.P. Glaister FisheriesDivision, QDPI POBox46 Brisbane OLD 4001

Mick Olsen wanted to know what percentage of outreach to an InformationEducation Section of the budget is ever put towards educational use information specialists. These specialists in turn amongst the fishermen, for example in Alaska? have a fight to get the biologist to even talk to Did Stan Moberly have to use very much of them - because they won't be busied with them. funds allocated to the programme he directed to And often, even in the Information Education make the fishermen understand what they were Sections, when budgets are shrinking so does trying to do in fisheries management? the outreach program. They continue to produce the information and do even less outreach. Stan Moberly thought the answer was no. Through the F.I.S.H. ("Fishermen Involved In The mandates are given that direct managers to Saving Habitat") Coalition, on the other hand outreach and infmm fishermen but when you there is no attempt to create any new informa­ look at the budgets of the programmes you find tion or educational material. There is already that almost all of it is allocated to collecting sufficient information available if only it can data, not to turning the data into useful informa­ reach people so that they are aware of conditions tion and then outreaching the information to or circumstances. If people who are concerned fishermen. Outreach is almost always stated as about aquatic resources are infmmed they usu­ a programme goal and something managers say ally support a higher priority to conservation they want to do. Stan Moberly sits on the Advi­ and protection of these resources. sory Committee for the Secretary of Commerce which has responsibility for management of the Peter Young commented that at the Interna­ nation's living marine resources. When you tional Fisheries Congress in Athens earlier on in look at the federal program you find strong the year there was a lot of talk from social mandates for protecting and conserving habitat scientists, particularly fromthe USA, complain­ and for outreaching to the fishermen and the ing bitterly that they had been effectively ex­ public. But when you examine the budget and cluded from the whole fisheries management see how the agency allocates its resources then process. Did Stan Moberly think that in the USA you see the true picture. What the agency says it there is an increasing awareness that these peo­ is going to do is one thing but what they really ple can actually be allies in the whole process do is revealed in the budget process, which is and become a very powerful lobby on behalf of that the agency has allocated little to protecting these kinds of issues? and conserving habitat and outreach to the pub­ Stan Moberly believed they are an essential lic and the fishing industry. part of the process. Fisheries are a common Another thing that complicates the situa­ resource and belong to the public. In the mid tion further is that fishery biologists do not like 1980's the American Fisheries Society created doing this work, so they often transfer the task of its first dual-disciplined section called the bio-

14 Bureau of Resource Sciences Proceedings engineering Section.You wouldn't guess where different approaches. Is there any quantitative most resistance in the Society came from - the information as to which is the best approach fish culturists. Fish culturists require expertise towards activating the community response? and assistance of engineers to construct Stan Moberly thought there wasn't enough successful culture facilities. Stan Moberly experience for that. He could only point to what believed that fish culturists would "pour their had actually worked. It was less a question of own raceways" if they could secure the building obtaining new information, which would have permits. Administrative procedures and building been the easier option, than of circulating and codes require that licensed engineers be part of doing outreach with already available material. the process of designing and building fishculture The difficultpart is transferringinformation to facilities. Despite the resistance, the next attempt those who need the information so that they can at a dual-disciplined section was to bring in the involve themselves in the decision processes. anthropologists and the economists to try to The most powerful process the F.I.S.H. Coali­ form a Socio-economics Section. This effort tion offers is for getting the diverse, warring was successful and occurred without much components of the fishing community talking to resistance. The Society was changing. The theme one another and all marching in the same direc­ of the Society's 1988 annual conference,held in tion at least on one issue--conservation of Toronto, was centred around "what is aquatic habitat. In North America, those in the biologically possible, economically feasible and fisheries community have a reputation of can­ politically doable," that fish management is a celling each other out-sports fishermen lobby "three-legged" stool. This is the part of the their point of view followed by the commercial whole system that fisheries scientists haven't fishermen followed by the scientists followed been trained to do. We look and observe and by the land developer and so on, by which time collect data and enjoy our jobs but never expect the politicians are pretty comfortable in not that we would have to transform what we see doing anything. If we expect change and if we and know into information beyond our own expect the political process to work for us we disciplines. But in modem fisheriesmanagement must reach consensus as much as possible and it is absolutely essential that we do this. We have then represent our position in the political proc­ to understand and interact with disciplines such ess. The members of the F.I.S.H. Coalition as engineering, economics and sociology. We reached consensus on the necessity to conserve don't number enough! There are approximately and protect aquatic habitat and then, when they 18,000 fisheries professionalsin North America all marched together with this message, the but there are tens of thousands of engineers­ politicians started to pay attention. When the and they don't spend very much of their time Coalition lobbied in Washington, the team con­ designing and helping to build fish hatcheries; sisted of a representative from the top recrea­ they're pushing dirt around the shoreline and tional fishing groups, one from the National building condominiums and highways. We need Wildlife Federation (representing the environ­ a multi-disciplined approach in managing mental community), one fromthe commercial fisheries as there are too many competing fishing industry and one representing the scien­ interests for habitat essential forfish. He noted tists and managers, and the four of them visited that we are seeing more and more of a multi­ Congressmen and Senators. The essential ap­ disciplined approach in North America and he proach is to be seen to be in agreement to lobby hoped that it will continue. for those issues on which consensus can be Bryan Pierce's opinion was that the educa­ reached. tion component within South Australia and Stan Moberly suggested that the Society Australia all over is generally lacking. The Aus­ has two roles-one is its traditional role of tralian Fisheries Service has tried quite a few scientists and managers, and the other is to

Bureau of Resource Sciences Proceedings 15 function as an "honest broker" to mn a neutral podium, to call the meetings, to be the gelling agent, the catalyst and to assist the fisheries community in reaching agreement as much as possible and to work together on those issues they agree upon. He thought that probably this approach has to be the formula, at least this seemed to be working forthem in No11h America. Its better to fight for those issues you agree upon than fight over what you disagree on! And everyone agreed that it was more fun to fight over more fish than less fish! Less fish is the result of lost habitat.

16 Bureau of Resource Sciences Proceedings SESSION 2

A MANAGER'S VIEW OF FISH HABITAT

Session Chairperson: R.K. Lewis Session Panellists: K. Edyvane R.H. Winstanley P .D. Jackson Rapporteur: G.M. Newton 18 Bureau of Resource Sciences Proceedings CHAIRPERSON'S INTRODUCTION

R.K. Lewis South Australian Department of Fisheries GPO Box 1625 Adelaide SA 5001

Fisheries managers are required to assimilate It can be arguably stated that the era of various data sources into management plans modem fisheries management reflecting this that address: intent has been the last 20-25 years. However, regrettably, the history of fisheries manage­ ecosystem maintenance; ment over this period has not been the achieve­ sustainable exploitation; ment of the intent/level of expectations. Until recently most of the research/data sets have had • social and economic demands aimed at a single species/stock perspective. maximising the benefits to individual, spe­ cific groups and the current generation of Without an holistic/integrated/ecosystem- resource users, to the possible detriment of based approach two outcomes have resulted: the community in general and future generations; Many species and stocks have been sys­ tematically overexploited through serial competing uses for particular habitats. depletion, because of the tendency to con­ Fisheries management has al ways been es- centrate on a specific component of the poused as being based on sustainable develop­ ecosystem or stock and only redirect atten­ ment. tion when other components have become threatened, and a preoccupation with the This intent has been reflected in almost all problems associated with the original fisheries legislation e.g. the South Australian components. Fisheries Act which is directed towards: There has been a failure to present advice • ensuring through proper conservation, on an integrated/ecosystem basis and there­ preservation and fisheries management fore to "educate" the community/industry/ measures, that the living resources of the politicians to think on an holistic basis as waters to which this Act applies are not well as on the traditional fisheries view­ endangered or overexploited; point. achieving the optimum utilisation and eq­ These have resulted in: uitable distribution of these resources; and a failure by these sectors to recognise the • the Department of Fisheries "Mission State­ interrelated dependence of each compo­ ment", which aims "To conserve living nent of the system; marine and freshwater resources and develop them on behalf of current and the need for a greater commitment to the future generations." maintenance of the system's integrity;

Bureau of Resource Sciences Proceedings 19 a failure to recognise the collective extent the need to reconcile the views of those of serial depletion; trained in the more traditional fisheries management methods compared with those the need for a greater commitment to com­ advocating the holistic integrated ecosys­ bat loss of habitats etc through other factors tem-based approach. such as pollution, urbanisation; As an example, in the South Australian the commonly held image of fisheries and Department of Fisheries this very issue has fishers as exploiters/plunderers, rapers. recently been vigorously debated. These have occurred despite warnings from Our three speakers, one each from the ma­ relevant scientific/managementsectors. rine, estuarine and freshwater areas, will present In recent years this situation has improved. overview and case study data to illustrate these With the greater/increased awareness of envi­ points. ronmental issues by a wide cross section of the community (ie the "greening" of the world) the required holistic/integrated/ecosystem approach has achieved greater prominence, support and credibility. This is reflected through initiatives such as: Draft National Strategy for Ecologically Sustainable Development-3 recommen­ dations; Biodiversity; Resource Assessment Commission, Coastal Zone Enquiry; A National Strategy for the Conservation of Australia's Biological Diversity; Ocean Rescue 2000. The challenge for fisheries managers is to recognise the changes that are occurring, and to assimilate and apply them, both in the manage­ ment of fisheries as well as in the wider educa­ tive role for management. Our keynote speaker Stan Moberly, suggested activism. Whilst this may appear self evident and sensible, it may not be simple to achieve. This is because of: the need for greater financial and personnel resources (just look at the costing associ­ ated with the sustainable development proposals); the need to develop analyses and method­ ologies to handle other than single species data bases;

20 Bureau of Resource Sciences Proceedings AN ECOSYSTEM-BASED APPROACH TO MARINE FISHERIES MANAGEMENT

K.S. Edyvane SA Department of PrimaryIndustries (Fisheries) GPO Box 1625 Adelaide SA 5001

Abstract processes and life-support systems, and also, the establishment of research and monitoring Large-scale, multiple-use management is an programs to monitor the effectiveness of ideal vehicle to implement and develop a holis­ management strategies. The challenge for tic, integrated, ecosystem-based approach to 'fisheries managers' will be to redefine and fisheries management. It is now widely recog­ broaden their role as 'habitat managers' within nised that fisheries management must comprise a new, integrated, ecosystem approach to a subset or component of a broader manage­ management. ment of the whole ecosystem. Because of the "connected" nature of the marine environment, marine ecosystem management must address Introduction both system-oriented strategies, to prevent harm frompollution and overuse, and site-based strat­ In recent years there has been a new ecosystem­ egies to protect habitats or to allocate and based focus in the field of natural resource separate conflictinguse. Large-scale, multiple­ management. This has arisen primarily fromthe use managed areas, such as marine protected continued decline of our natural resources de­ areas (MPAs),provide an ideal tool forimple­ spite massive regulatory efforts,and the recog­ menting such an ecosystem approach to fisheries nition that there is a need to sustain ecosystems, management. in addition to the resources they produce (Kessler et al. 1992). In this new approach, ecological The role of the 'fisheries manager' should processes are given value and importance be­ be to provide input into: (i) the broad strategic yond the traditional commodity and amenity approach to ecologically sustainable uses of ecosystems. These ecological processes management, which will involve the use of include the provision and maintenance of a environments and natural resources on a regional wide range of ecological "services", fromcli­ scale which matches the scale of marine mate regulation, protection from erosion, nutri­ ecosystems, and (ii) tactical habitat management, ent storage and cycling, pollutant breakdown which will address a range of specificobjectives and absorption, to, in terrestrial ecosystems, such as biodiversity preservation, research, soil production and the maintenance of hydro­ education and recreation, in addition to fisheries logical cycles (ie. groundwater recharge, water­ management. shed protection, and the buffering against The goal of the 'fisheries manager' should extreme events). These ecological "services" be to ensure the sustainable utilization of species and functions not only produce and sustain our and ecosystems. Inevitably, this will be linked natural resources but also underpin the quality with the maintenance of essential ecological of our life and our economy. In terrestrial eco-

Bureau of Resource Sciences Proceedings 21 systems, this philosophy has been embodied Developing a marine ecosystem within the concept and practice of "total catch­ management framework ment management". Proponents for the sustainable use of marine In marine resource management, as in ter­ resources have long recognised the need for the restrial resource management, there is also a protection and maintenance of essential eco­ growing awareness of the need to adopt a holis­ logical processes. For instance, the World Con­ tic, ecosystem-based approach to the manage­ servation Strategy in 1980, clearly identified the ment of our marine resources (Commonwealth preservation of life support systems as one of of Australia 1991a). Despite regulatory efforts the four key elements in its global survival by individual agencies, pollution from point and strategy. The four elements of this strategy diffusesources, overfishing, loss of habitat from include: urban growth and coastal developments, and the maintenance of essential ecological conflicts between competing user-groups (ie. processes and life-support systems; fishing, aquaculture, tourism, recreation and conservation groups) continue to threaten our the preservation of biological diversity at marine habitats and fisheries (see Common­ all levels, from ecosystem to genetic wealth of Australia 1991b ). Further, the greater diversity; degree of "connectedness" in marine ecosys­ the sustainable utilization of species and tems, compared to terrestrial ecosystems; the ecosystems; and great mobility of organisms; and the extraordi­ • nary ability of water to transport both sub­ the establishment of research and monitor­ stances and organisms, result in the activities of ing programs to monitor effectiveness and one user group being more likely to directly and environmental and global change (IUCN/ indirectly affect the activities of another WWF/UNEP 1980). (Kelleher and Kenchington 1991). For these In translating this conservation strategy to reasons there is a greater need for integrated our oceans and coastal ecosystems, we must management of marine ecosystems. recognise the strong linkages between the land, the ocean and the atmosphere, as well as recog­ In order to sustain our marine resources, it nising the "connectivity" of marine ecosystems. is now increasingly being recognised that fish­ As such, land-based activities greatly influence eries management must be considered a compo­ the state of our coastal regions and its resources. nent or subset of multiple-use, whole ecosystem At a global level, almost 80% of marine pollu­ management (Commonwealth of Australia tion is derived from land-based sources, with 1991a). In this ecosystem-based approach to direct discharges accounting for some 44% and management, fisheries management is integrated approximately 33% entering the marine envi­ and coordinated with the management of other ronment as atmosphericinputs (GESAMP1990). uses and activities such as wastewater, ship­ For this reason the conservation and manage­ ping, tourism, recreation, conservation, mining, ment of marine ecosystems and their resources and industrial uses. While sectoral tasks and must ultimately entail effective management of management to some extent may still use tradi­ land-based activities. At a global level this con­ tional methods, the real challenge in this new cept of integrated management of the land:sea approach lies in ensuring effective intersectoral boundary is known as Integrated Coastal Zone management. One of the greatest challenges for Management (ICZM). fisheries managers as we approach the next century will be to redefine and broaden their role As stated in the World Conservation Strat­ as 'habitat managers' within this new frame­ egy, a management strategy for conserving and work of marine habitat management. managing ecosystems must include not only

22 Bureau of Resource Sciences Proceedings protection of the diversity of life, but also the Australia 1991a) clearly identifiedthese objec­ essential ecological processes and life-support tives and further, recommended a number of systems which support it. Hence, for marine key steps to achieve the ecologically sustainable ecosystems, an integrated management strategy use of our fisheries resources. Many of these must comprise conservation of the attached recommendations are useful in formulatinga set fauna and flora of the seabed; water quality; the of guidelines for achieving an ecosystem ap­ fauna and flora which live in the water column; proach to fisheries management (see Table 1). and the key ecological processes (such as cur­ rents, tides, etc.) which sustain the ecosystem. Management of a seabed by itself without ad­ dressing pollution or overfishing will have little Multiple-use, marine protected areas effectin the conservation or sustainable use of and fisheries management marine ecosystems. As such, an integrated man­ In recent years there has been a dramatic shift in agement frameworkfor natural ecosystems must the role of marine protected areas (or MPAs) in comprise two essential components: fisheriesmanagement. Until recently MPAs were (1) general ecosystem protection to prevent seen primarily as sites for the protection of harm from pollution and overuse; and 'critical habitats' of economically important species. Estuaries and wetland habitats, such as (2) site-based protection to protect habitats or seagrasses and mangroves, were included be� to allocate and separate conflicting uses cause they protected key parts of the life history (Kenchington 1990). of species. Specific fisheries were enhanced by For the management of marine ecosystems the protection of identified nursery areas, feed­ and their resources these components translate ing areas and spawning areas. MPAshowever, into two approaches: can provide a number of other important roles in fisheries management, in addition to critical (1) a broad strategic approach to ecologically habitat protection. These include: areas for stock sustainable use and management of envi­ replenishment, ie. 'harvest refugia'; areas for ronments and natural resources on a scale monitoring the natural fluctuationsin stock; and which matches the scale of marine ecosys­ areas for resolving conflictbetween competing tems; and users of marine resources and habitats. In the (2) tactical site or marine habitat management latter regard, MPAs are increasingly being seen to address specific objectives ofbiodiversity as a vehicle for implementing an ecosystem­ preservation, research, education and rec­ based approach to fisheries management. reation. The essential tool of multiple-use, Measures which seek to address the tactical ecosystem-based management in MPAs is the objectives of habitat management without the zoning of human uses and activities on a broader strategic framework are likely to fail to geographicalbasis. Uses such as fishing,tourism, address the broad requirements of conservation recreation, conservation and maritime shipping, and the sustainable use of marine ecosystems are essentially coordinated and integrated (Kenchington 1990). For an integrated approach through the development of a zoning plan. to fisheries management there is a need to in­ Zoning not only provides a mechanism for clude the essential components of ecologically reducing conflictbetween competing user groups sustainable use and also, recognition of the need but it also provides a mechanism for the effective for ecosystem management. The recent report protection of' critical areas' through the creation released by the Ecologically Sustainable Work­ of 'bufferzones' . Probably the most well-known ing Group for Fisheries (Commonwealth of example of multiple-use management of a marine

Bureau of Resource Sciences Proceedings 23 ecosystem in Australia is the Great Barrier Reef ecological experiments can be conducted through Marine Park in Queensland. Within this 348 700 the zoning mechanism to investigate the effects sq .km park, fishing and a wide variety of other of a particular management regime. For in­ human uses (including tourism, recreation, stance, in certain parts of the Great Barrier Reef preservation and scientific research) are managed Marine Park, zoning regulations are presently on an ecologically sustainable basis through six being used to establish the ecological effectsof types of zones within the marine park (GBRMPA particular fishing methods. In this self-regula­ 1985). All activities are both managed and tory approach to fisheriesmanagement, the man­ coordinated on an integrated basis by a single agement regime is adjusted and regulated through regulatory authority, the Great Barrier Reef the results of monitoring. Marine Park Authority. In recent years the establishment of large, Zoning of uses is a viable approach to multiple-use managed marine areas in Australia marine fisheries management that deserves se­ has received greater attention with the announce­ rious evaluation. Not only is it an ideal tool for ment of a national, 10-year marine conservation implementing an ecosystem approach to marine program called 'Ocean Rescue 2000'. One of resource management, but it also has the poten­ the essential elements of this program is the tial forincreasing consistent sustained harvests establishment of a national, representative sys­ through the creation of 'harvest refugia'. Fur­ tem of MPAs. While some states in Australia ther, zoning also allows reduced fisheries regu­ (such as Queensland and Western Australia), lations and thus can simplify enforcementand have established several large, multiple-use compliance. It may also allow dynamic market marine parks, some states such as South Aus­ forces to optimize harvest sizes and seasons, tralia have yet to establish large, multiple-use and may permit those same forces to drive managed areas (Table 2). In these States, contin­ development of more efficient nondestructive ued funding under 'Ocean Rescue 2000' will be fishing gear (Davis 1989). critical in establishing such areas. While multiple-use zoning has yet to be In summary, the increasing importance of implemented in many regions and countries, MP As as tool for fisheries management is a sign habitat management is increasingly being rec­ of a new ecological order for fisheries manage­ ognised as an essential component of fisheries ment. This recent change in focus stems prima­ management, in addition to the traditional sin­ rily from the failure of traditional single-species gle-species approach to management. This is based management practices to halt the decline evidenced by a recent proposal in 1990 to estab­ of fisheries resources. More than ever, MPAs lish large fisheryreserves offthe Atlantic coast are increasingly being seen as a vehicle for a of the South-Eastern United States. In this pro­ new order of ecosystem-based management of posal, reef fishes would be managed by both fisheries, rather than the traditional single-spe­ conventional means of size and bag limits, and cies approach to management. The challenge by the establishment of a set of marine reserves, for 'fisheriesmanagers' will be to redefine and where reef fishing would be prohibited (Hunts­ broaden their role as 'habitat managers' within man and Vaughan in press). The proposed ma­ this new, integrated, ecosystem approach to rine reserves would encompass some 20% of the management. region's reefs. Large-scale zoning is also of immense value in 'adaptive management'. Management plans can use zoning as a research tool to establish a framework for scientific testing of concepts, methods and assumptions. As such, large-scale

24 Bureau of Resource Sciences Proceedings References Table 1. Guidelines forachieving an ecosystem Commonwealth of Australia (1991a). Ecologically Sustain­ approach to fisheries management (adapted from able Development Working Groups Final Report­ ESD Fisheries 1991) Fisheries. An Ecosystem-Based Approach to Commonwealth of Australia (1991b). The Injured Coast­ Fisheries Management line. Report of the House of Representatives Standing Committee on Environment, Recreation and the Arts Goals (HORSCERA). Recognition of fisheries management as a Davis, G.E. (1989). Designated harvest refugia: the next subset or component of ecosystem man­ stage of marine fishery management in California. agement. CalCOFI report, Volume 30. • Adoption of ecologically sustainable use GESAMP (IMO/FAO/UNESCO/WMO/WHO/IAEA/UN/ and inter- and intragenerational equity as UNEP Joint Group of Experts on the Scientific As­ pects of Marine Pollution) (1990). The state of the goals of fisheries management: marine environment. Rep.Stud.GESAMP 39:lllpp. sustainable utilization of species and Gilmour,A.J. andJ. Connor(1991). Aproposalforlegaland ecosystems; institutional alternatives for the consideration and management of Australia's maritime ecosystems. Pa­ maintenance of essential ecological per prepared forthe Australian Conservation Founda­ processes and life-support systems; tion and the World Wide Fund forNative Australia. Melbourne, June. the preservation of biological diversity at all levels, fromecosystem to genetic Great Barrier Reef Marine Park Authority (1985). Zoning the Central Section. Townsville, Australia. diversity. Huntsman, G.R. and D.S. Vaughan(in press). Relative risks in managing reef fishes between marine reserves and Management size/bag limits. Proc. World Fisheries Conf. 1992. • Establishment of Marine Protected Areas IUCN/UNEP/WWF (1980). A Strategy for World Conser­ (MPAs) involving large-scale, regional vation. IUCN/UNEP/WWF, Gland, Switzerland. management of multiple-use areas for: Kellaher, G. (1991). Cost recovery for fisheries, Submis­ resolving conflict by competing user sion to the Industry Commission draft report. Cost groups through zoning activities; Recoveryfor Managing Fisheries, Great Barrier Reef Marine Park Authority, Canberra. protection of biodiversity; Kelleher, G. and R. Kenchington (1991). Guidelines for enhancement of fisheriesmanagement, Establishing Marine Protected Areas. IUCN, Gland, Switzerland. through refuge sites for stock replen­ ishment, and protection of fish nursery Kenchington R.A.(1 990). Managing Marine Environments. areas. Taylor and Francis, New York.

Kessler, W.B., H. Salwasser , C.W. Cartwright and J.A. Adoption of adaptive and flexiblemanage­ Caplan (1992). New perspectives forsustainable natu­ ment methodologies (such as Adaptive En­ ral resource management. EcolAppl. 2, 221-225. vironment Assessment and Monitoring), McNeill, S. (1991). The Design of Marine Parks with an which recognise the uncertainty associated Emphasis on Seagrass Communities. MSc thesis, with resource management of biological Macquarie University. systems. Promotion of habitat amelioration and en­ hancement (adopt principle of 'no net loss' of habitat).

Bureau of Resource Sciences Proceedings 25 Conservation of both 'critical' and 'eco­ Research logically representative' habitats for fish­ Identification and conservation of the criti­ eries management. cal ecological processes and habitats which sustain fisheries, eg. upwellings, environ­ Management of environments and natural mental "cues", nursery areas, feeding ar­ resources on a regional scale which matches eas, breeding areas, "sinks" or "sources" the scale of marine ecosystems, for in­ for larvae. stance: Identification of the spatial and temporal Marine Protected Areas (MPAs); scale of the critical ecological processes. National Maritime Authority (proposed Assessment of the impacts of pollution, by Gilmour and Connor 1991 ); fishing, aquaculture and fishing methods Coastal Zone Management Authority on critical ecological processes and habi­ (proposed by Kelleher 1991 ). tats (ie. assess ecosystem and habitat integ­ rity). Development of an integrated management framework: Separation of the effects of overfishing from the effects of habitat degradation (a 3-5 year strategic management plans combination of both?) by identifying: for all fisheries (including critical habi­ tats and ecological processes, poten­ relationship of fish to habitat; tial threats, and performance and effect of environmental influences on sustainability criteria); habitat. greater community and industry in­ Determination of the need, purpose, loca­ volvement in decision-making proc­ tion, design and size of marine protected esses; areas and their role in maintaining a par­ management of fisheries on a multi­ ticular_ species and/or aquatic ecosystem. species level; Development of more robust predictive initiation of intersectoral management tools for stock assessment, environment mechanisms: assessment and bioeconomic analysis. * regional and State "ecosystem" Development of data information/retrieval committees (to address intra­ systems such as GIS (Geographical Infor­ sectoral and intersectoral issues), mation System). in addition to traditional single­ Development of predictive, adaptive, GIS­ species fishery committees; based, multi-species models to manage fish­ * use large-scale, multiple-use eries ( eg. AEAM (Adaptive Environmental MPAs as a tool for fisheries man­ Assessment and Management) and ecosys­ agement and vehicle for ecosys­ tem-based models). tem management. Development of biological and ecological criteria to assess the goals of sustainability and "ecosystem health", with statistical power to detect effects of unsustainable use. Development of economic criteria to assess sustainability.

26 Bureau of Resource Sciences Proceedings Table 2. Marine protected areas (MPAs) in Australia, up until 31 May 91 (adapted fromMcNeill 1991). Figures include the number of MPAs in each State/Territory; total area of MPAs in each State/ Territory; area of MPAs as a percentage of total State/Territory waters; area of MPAs as a percentage of total area of MPAs in State and Commonwealth waters; area of MPAs as a percentage of total area of MPAs in State and Commonwealth waters minus the area of the Great Barrier Reef Marine Park (GBRMP)

%Area Area %Area %Area Total State/Territory No. km2 State Total -GBRMP

Queensland 139 354 799 24.5 90.5 21.2 ExternalTerritories 4 17 975 4.6 38.0 WesternAustralia 19 14 328 20.3 3.6 30.4 Northern Territory 10 2 841 8.2 0.7 6.0 New South Wales 22 924 8.7 0.2 2.0 Victoria 27 537 5.4 0.1 I.I Tasmania 17 488 2.8 0.12 0.6 South Australia 28 295 1.4 0.07 0.6 ACT 4 8 4.0 0.002 0.02

Bureau of Resource Sciences Proceedings 27 ESTUARINE ISSUES FROM THE MANAGER'S VIEWPOINT

R.H. Winstanley Marine Science Laboratories, Department of Conservation and Environment PO Box 114 Queenscliff VIC 3225

Introduction In the fields of fisheries management (and here I include aquatic conservation), the man­ The ecological value of estuaries and their im­ ager is the link between the scientists and the portance to fisheries have been appreciated for politicians in the decision-making and planning many years. So too has the array of fishing and processes. environmental factors-in the estuaries, their catchments and adjacent coastal waters-that This can be a difficult place to be in any impacts on estuarine fish stocks and ecosys­ field. It is a difficult place to be in fisheries tems. Long before the term "ecologically sus­ management. It is a particularly difficult place tainable development" was coined, the concept to be in relation to estuaries where the range of of "ecological sustainability" of estuaries and competing interests and pressures operating on their fish resources was well established amongst the fish resources and their habitats are so management agencies, fishers and the wider numerous and complex. community. In this environment, manager must ensure From a background where the focus was on that research effort is focused on the critical the exploited fish stocks, management attention long term and short term information-gathering has shifted towards managing fisheries in the programs. broader context of estuarine living resource Without understanding the continuing dif­ conservation. Clearly, this can only be achieved ficulties, there are a number of factors which through understanding the ecological linkages have changed in a way that promises real hope between fish stocks and estuarine habitats and that the ecological basis for estuarine fish stock the impacts of polluting and disturbing factors conservation will be achieved. on those habitats and stocks. In the past, all of this often seemed too hard, the information base too small and the ecologi­ Where are we today? cal enormity of the task too daunting. The politi­ cal balance appeared too heavily weighted in Karen Edyvane has outlined the various factors favour of commercial activities and economic which impact on estuarine (and other) habitats development goals, most of which are funda­ and, over the next two days, we will hear of the mentally incompatible with the long term main­ importance of estuarine fish stocks and habi­ tenance of estuary habitats and fish stocks. tats, so I will not detail them here.

28 Bureau of Resource Sciences Proceedings In the 1990s, we are mainly dealing with In many instances, the EIS and planning highly modified estuaries. This situation arises processes are taking place without early input from: from aquatic resource managers. As our keynote speaker has already pointed out, we must be­ our history, which saw estuaries and marine come more assertive and proactive and commu­ embayments as the sites of our earliest nicate our message more effectively to ensure settlements, and the intensification of that estuarine fish and habitat conservation is­ population concentrations and associated sues are placed firmly on the agenda of all of the aquatic impacts ever since; and agencies involved in these processes. • the fact that estuaries are where the impacts We are often constrained by problems of of mismanagement in the catchments and overlapping and fragmented jurisdictions and hinterland converge. responsibilities, and the absence of clear overall In addition, while those of us in fisheries aquatic conservation strategic plans; this applies agencies have been attending to long-standing at both state/territory and federal levels. Some­ problems, we have been overtaken by new times, we are further constrained by deficient factors such as the deliberate development and legislation which does not provide the powers usage of products ( e.g. tributyl tin anti fouling needed to underpin effective habitat protection. paints) and industries (e.g. ecotourism) and the For example, in Victoria, we have the Fish­ inadvertent spreading of exotic organisms. In eries Act providing the powers for commercial some cases, introduced organisms have come and recreational fisheries management; we have to dominate estuarine communities; in other the Flora and Fauna Guarantee Act providing the instances, exotic toxic algae have threatened powers to protect designated species or commu­ aquaculture and shellfish harvesting industries. nities from threatening processes; we have the Consequently, fisheries managers have Environment Protection Act providing the pow­ struggled to achieve the proper recognition and ers to maintain water quality standards; and we effective conservation of estuarine habitats. have the National Parks and Land Acts provid­ ing the powers to manage public land. However, We lack basic informationon: there is a large hole in this legislative combina­ the ecology of fish species at every stage of tion which severely limits our broad marine and their life history; estuarine conservation powers. • the critical habitat requirements of these In short, fisheries and aquatic conservation stages; managers frequently lack both the information and the authority to properly protect the fish and the distributing or polluting factors which aquatic habitats forwhich they are responsible. impact or threaten to impact on those habitats. Too often, managers and interest groups have been preoccupied with symptoms rather This has weakened ourability to put credible than causes of fish habitat problems. In some and successful cases to ensure that development instances, anglers push artificial reef proposals activities proceed in ways that do not while agencies struggle to protect threatened compromise estuarine fish stocks and habitats. productive natural reef habitats. The onus of proof in Environmental Impact Statements (EIS) and related planning processes Too often, governments are facing up to continues to fall on aquatic resource managers­ problems only when they have deteriorated to not on developers. crisis point, for example:

Bureau of Resource Sciences Proceedings 29 the recent focus on national blue-green involve all interested agencies and groups; algal blooms in inland and estuarine waters; are supported by legislation. • improvements to Sydney's sewage As an aside, it is interesting to note that what treatment and disposal; has been happening nationally is mirrored in this responses to public health scares over Society: the shift from a focus on fin-fish and Georges River oysters. their biology, to a wider range of aquatic species, to fisheries issues, and now to fish and aquatic In each case, the problems have been known habitat conservation-hence this workshop! for years. In instances like the current plan for Clearly, this professional society has a signifi­ treating the eutrophication problems of the Peel­ cant role to play in leading agencies, govern­ Harvey Inlet, the costs of belated treatment of ments and community responses to these issues. the symptoms are huge. Fisheries managers stillface the widespread and dangerous misconception that, provided we Wider community responses establish representative Marine Protected Areas and protect designated threatened species and On a wider front, there are a number of promis­ communities, we are doing a thorough job of ing signs. habitat conservation. We have noted the upsurge in community concern about marine and estuarine conserva­ tion issues in the last few years. Government responses Commercial fishing industry organisations In the face of these challenges and impediments, are moving away from reacting to specific envi­ state and territory fisheries agencies have in­ ronmental issues (e.g. coastal discharges, pulp creasingly focused resources on estuarine habi­ and paper mill proposals) towards proactive tat research and management programs. For campaigning for.fish habitat protection. In NSW, example, the NSW Fisheries biennial report of the industry has established Ocean Watch to fisheries indicates a large commitment to this advise it and to act as its advocate on marine area during the 1989-1991 period. conservation issues. Similarly, the Queensland Commercial Fishennen's Organisation has en­ Increasingly, fisheries agencies are giving gaged professional assistance to promote fish prominence to aquatic habitat protection as a habitat protection, particularly in estuaries. cornerstone of their corporate plans (e.g. SA Department of Fisheries) and strategic research Recreational Fisheries bodies are increas­ plans (e.g. NSW Fisheries). ingly taking an active part in water and land management reviews and in marine and estua­ To assist with planning and management at rine planning processes. all levels of government,information and guide­ lines for the conservation of estuarine habitats are being produced. Broad strategic planning frameworks Managing agencies are producing estuary- We should take further encouragement from the specific management plans which: increased attention to broad marine and coastal recognise the full range of community ben­ strategic planning. efits arising from the estuaries; For example, at a national level, the Ocean consider the cumulative impacts of pollut­ Rescue 2000 program and Resource Assessment ing and disturbing factors; Commission coastal zone enquiry will provide a

30 Bureau of Resource Sciences Proceedings broad frameworkfor the future of marine con­ servation and coastal management planning. At the state level, the Victorian Land Con­ servation Council, a public land management planning body, is preparing a strategic planning frameworkfor coastal management and marine conservation in Victoria. The promise of the national Ecologically Sustainable Development program is that it will encourage and lock in all levels of government and all areas of public and private enterprise into a set of principles that place due emphasis on the conservation of estuarine resources. If we look at current national initiatives in areas such as Landcare, salinity control and catchment management, we see references to "holistic approaches", "whole ecosystem man­ agement" and "total catchment management". This indicates that there is a widespread conver­ gence occurring in the mindset and goals of all those involved in the usage and management of natural resources across Australia. By adopting proactive strategies, fisheries managers should be able to capitalise on the momentum of this movement to make new allies in addressing the task of protecting fish habitat. In conclusion, many people are sceptical and these current aquatic and wider conserva­ tion initiatives may prove to be mainly rhetoric-or passing fads. We must recognise that no habitat protection policies and strategies can be relied upon to have the desired effect if they are based on inadequate knowledge or if they lack total commitment by all parties.

Bureau of Resource Sciences Proceedings 31 FRESHWATER HABITAT PRO TECTION­ A MANAGER'S PERSPECTIVE

P.D. Jackson Fisheries Division, Queensland Depat1ment of Primary Industries GPOBox46 Brisbane OLD 4001

Introduction tributaries in forested areas or catchments con­ tained wholly within National Parks, will there Many of Australia's inland aquatic habitats are be no change in aquatic habitats. Multiple use of seriously degraded, some to the point where catchment resources will inevitably mean change. their long-term ecological sustainability must be in serious doubt (Hart 1992). From a fisheries Given the above, the data required by man- viewpoint, habitat degradation has been impli­ agers may be summarised as follows: cated in the decline of many native species. The What are the most important areas ofhabitat Freshwater Fish Action Plan (Wager and Jackson to protect? in press) lists habitat degradation along with Baseline data must be available on existing negative interactions with introduced species as habitats and their fish communities. Are the major threatening processes for freshwater there priority habitats to be protected? Are fishes (see also Jackson, Koehn and Wager this there particular tributaries within a catch­ meeting). Fish under threat range from small ment that are more important than others? species of high conservation value such as the This may be important if there are multiple honey blue-eye (Pseudomugil mellis) to impor­ choices for a proposed impoundment site tant recreational species such as Murray cod for example. (Macculloche!la pee/ii). What are the key characteristics of the This paper looks at the protection of fish habitat? habitat from a manager's perspective and uses It is important to determine the habitat vari­ the plight of the Mary River cod (Maccul!ochel!a ables that are predictive of fish community sp.) to illustrate some of the points. structure. What are the habitat characteris­ tics that a manager must try to protect? Managing inland waters What are the trends? Is the habitat stable or is it degrading? Managing habitat for long-term sustainability of fisheries in inland waters is inevitably about • What are the acceptable levels of change in managing competing uses of resources within a habitat variables? catchment (e.g. instream vs offstream use of What are the boundaries of acceptable water, land use for agriculture vs retention of change? For example, how much water can catchment vegetation etc.). Protection of habitat be harvested for offstream use and how cannot be achieved without consideration of much can the seasonality of flow regimes be land use practices within the catchment. In only altered without major impacts on fish very few circumstances, perhaps headwater communities.

32 Bureau of Resource Sciences Proceedings • What are the quantitative relationships be­ remainder is predominantly State forest with a tween habitat change and catchment significant amount of this being exotic pine. activity? What are the causal factors in National Parks account for less than 1 % of the habitat degradation and how can they be total catchment area. There are water storage managed? dams on three of the tributaries and further water It is important to establish the linkages be­ harvesting is planned. tween catchment activities and instream Although definite data are not available, habitat. Inevitably quantitative relationships threats to Mary River cod appear to include: will have to be established. For example, dams and weirs as barriers to movement, loss of what land use practices contribute to sedi­ native riparian vegetation, extensive siltation ment runoff and how can land use practices from catchment erosion due to land use prac­ ( at the on-farm scale) be modifiedto reduce tices, stream channel damage due to land use sediment contribution to an acceptable limit? practices, steam channel damage fromsand and • What are the habitat rehabilitation options? gravel extraction, possible competition with In certain circumstances management ac­ translocated species (golden perch, Macquaria tions to rehabilitate degraded habitat may ambigua and silver perch, Bidyanus bidyanus) be both desirable and practical. For exam­ and overfishing. ple, replanting riparian vegetation may be an option or it may be feasible to rehabilitate Available data the channel form to create appropriate habi­ In 1991, habitat surveys of the Mary River were tat diversity (e.g. pools and riffles etc.) in undertaken by stafffrom the Queensland Fish­ streams with reduced water flows. A man­ eries Divison' s SouthernFisheries Centre. These ager needs data on specific rehabilitation surveys have provided 'broad brush' infotma­ requirements. tion on the condition of instream habitat and disturbance types within the Mary River catch­ ment. Additional habitat information and fish The Mary River cod -a case study community structures in the Mary River have The Mary River cod (Maccullochella sp.) is an been obtained by Brad Pusey from the Centre important recreational angling species that has for Catchment and Instream Research, Griffith greatly declined in both numbers and distribu­ University. tion since the early 1900s. It is thought to be Data are available on land use within the identical to a fish that previously occurred in the catchment and some information is available on Brisbane, Logan, Albert and Coomera Rivers in the status of riparian vegetation from aerial south-eastern Queensland. It is currently re­ photographs obtained by the Queensland Forest stricted to a few larger tributaries of the Mary Service. River including Obi Obi, Six Mile, Tinana and Coondoo Creeks. It is generally found in deeper Information on Mary River cod distribu­ pools of these relatively undisturbed tributaries tion and abundance remains largely anecdotal where fallen timber, branches and boulders pro­ or is derived fromcatch records by local anglers. vide cover. The Mary River flows through a multiple Data requirements land use catchment after rising in the Conondale Clearly there are gaps in available knowledge Ranges north of Brisbane. The catchment area is that must be filled if Mary River cod habitat is to about 9595 km 2 of which approximately 65% is be effectively managed to ensure the long-term freehold agricultural or grazing land. The conservation of the species.

Bureau of Resource Sciences Proceedings 33 Definitive data must be obtained on the In the case of the Mary River, options for present distribution of cod in the Mary River future impoundment sites are being considered system together with more concise data on the now and preliminary data on cod distribution habitat requirements of the fish. The Queens­ must be used to ensure proper input to the initial land Fisheries Division has received funding planning process. Similarly, some management fromthe Australian National Parks and Wildlife options can be implemented immediately. A Service to undertake the necessary fish surveys good example is the protection of remaining this year. The information obtained will also native riparian vegetation and the implementa­ provide baseline data on cod distribution and tion of measures to revegetate stream banks. abundance and, together with future surveys, will enable trends to be evaluated. The links between instream habitat change Conclusions and catchment activities must also be established. Ultimately, managers require specific informa­ Ultimately management prescriptions will need tion on habitats, what are the key habitat vari­ to act at the individual fa1m level if they are to ables and what are the limits of acceptable be effective in the Mary River catchment. change. In many cases these data are not yet Finally there is a need to establish the available but often general information is avail­ acceptable levels of habitat change. Most press­ able on the broad threats to habitat (e.g. removal ing is the need to determine environmental flow of riparian vegetation, increased sediment in­ requirements in the tributaries containing cod, put, regulation of stream flows). Managers must e.g. Six Mile Creek and Obi Obi Creek already use the best available data to mitigate these have impoundments on them and more water effectswhilst encouraging and supporting habi­ harvesting is planned. tat requirement research.

Management options Effective protection and management of Mary References River cod habitat cannot be achieved without a Hart, B.T. (1992). Ecological condition of Australia's river. whole catchment approach. The Mary River Search 23, 33-37. catchment is to become a pilot catchment forthe Jackson, P.D., J.D. Koehn and R. Wager (this meeting). Queensland Department of Primary Industries' Australia's threatened fishes 1992 listing-Austral­ Integrated Catchment Management Initiative ian Society for Fish Biology. and a community driven catchment coordinat­ Wager, R. and P. Jackson (in press). The Action Plan for ing committee has already been established. Australian Freshwater Fishes. Australian National Ultimately a catchment management plan will Parks and Wildlife Sen•ice, !28pp. be produced and the protection of instream habitat will be part of that plan. Data obtained on specific habitat require­ ments of Mary River cod and effects of catch­ ment activities on cod habitat will enable effective management measures to be put in place. However, it is important to recognise that managers cannot always wait until definitive data are available and often must act on the best informationto hand at the time.

34 Bureau of Resource Sciences Proceedings DISCUSSION OF SESSION 2

Recorded by G.M. Newton Bureau of Resource Sciences GPOBox858 Canberra ACT 2601

The three panel presentations were each fol­ John Glaister maintained that habitat is an lowed by a short discussion, following which integral part of fisheries management and rather the Chairperson, Rob Lewis, opened the meet­ than move into a new area we need to focus on ing for more general discussion. current real issues. The first speaker, Karen Edyvane of the Karen Edyvane however, pointed to the South Australian Department of Fisheries, spoke example provided by the Great Barrier Reef of fisheries management as a subset of ecosys­ Marine Park Authority, which deals with a tem management. She emphasised the need to multiple use environment, requiring other user look at critical ecological processes and their groups to take part in the decision-making proc­ temporal and spatial scales, as well as to assess ess. We need to broaden our view! impacts on these processes by the various user The second panelist,Ross Winstanley, spoke groups of the marine environment. Monitoring about the need for a better understanding of fish criteria and indicators were seen as fundamen­ stocks dependent on estuaries. Barbara tal considerations. Greater use of information Richardson commented that currently the onus technology, Geographical InformationSystems of proof of habitat issues rests with fisheries (GIS), and predictive tools was encouraged. scientists and managers. The topic is of such John Glaister commented on Karen importance that there needs to be a change of Edyvane' s overhead transparency on manage­ onus, with involvement by other disciplines in ment of the marine environment, which advo­ decision-making about saving habitat, with con­ cated another level of bureaucracy e.g. the sequent better management. Australian Fisheries Management Authority Ross Winstanley agreed that a wider forum (AFMA), as the single responsible agency. is needed. For example, decision-making in Wasn't that flying against the principle of col­ Port Phillip Bay covers deepening of shipping lective wisdom? channels and dumping of sediment. Land dis­ posal is controlled by the Environmental Pro­ Karen Edyvane justified her viewpoint by tection Agency, but attention needs to be given suggesting a model for debating the issues may to effects underwater e.g. in dips and hollows. be through the formation of a single ecosystem committee. This committee could be formed by Rob Lewis commented that part of the community representatives of the various user answer lies in mobilising all sectors of the groups who would then discuss the issues re­ community so that they collectively own the lated to fisheries and potential conflicts. initiative.

Bureau of Resource Sciences Proceedings 35 Following Peter Jackson's panel presenta­ stakeholders. She also highlighted the fact that tion, which focussed on the data requirements of about 80% of decisions are influenced by local managers of freshwater habitats, Campbell governments and therefore may be out of our Davies suggested that because of the lack of data hands. relevant to survival of Mary River cod, the onus Stan Moberly questioned where fisheries should rest with the developers rather than the sit in the hierarchy. They should be involved in scientists, to show that their activities will not the strategic planning with influence equal to threaten the species. Peter Jackson responded irrigation, mining, forestry etc, not just respond­ that there is now little water remaining in the ing to Environmental Impact Statements on, for Mary River, and the onus is on water resource example, endangered species issues. authorities to facilitate the relevant research by fisheries scientists. John Koehn saw the management of threats to habitat--director indirect-as requiring links The Chairperson, Rob Lewis, led the gen­ with other agencies. The Flora and Fauna Guar­ eral discussion, which concentrated on issues of antee Act of Victoria ( 1988) provides forlisting research and assessment, on education and com­ of threatened species, and communities, and for munication, and on mobilisation of the commu­ threatening processes. nity, by referring back to John Glaister's earlier question about another level of authority. For­ Ross Winstanley stressed that the process is mal management committees e.g. boards of dependent on the availability and quality of directors for South Australian fisheries, have scientific information, on being able to distin­ specific responsibility and accountability, but guish clear viable links between fish, habitats there is a greater need for holistic, integrated, and processes. In marine coastal waters, threats ecosystem approaches, a need for new rather are still being responded to on a reactive basis than traditional mechanisms. We need to iden­ without the· equipment to utilise legislation. In tify the advice required by fisheries managers­ Victoria, the Fisheries Act precludes direct ex­ onus of proof, ownership, avoiding habitat ploitation, there is a mechani.-;m for marine change etc-but we do not have the bio-eco­ parks, the EPA controls water quality, but the nomic models needed to place economic values legislation does not provide for broader aquatic on fish stocks and habitats. The importance of conservation. integrative catchment management overrides Peter Jackson was concerned as to whether, the State perspective. although the Act recognises threats, it is effec­ Peter Young commented that over the last tive in practice. Does the action plan become five or so years greater significance has attached implemented or change anything? In the ab­ to other stakeholders-agriculturalists (includ­ sence of existing data, the onus must be on the ing aquaculturalists), mining, forestry, conser­ people affecting the habitat to prove it will not vation, tourism etc as well as fisheries interests. be altered or destroyed. Historically, decision-making has been by fish­ Karen Edyvane pointed out that a recom­ eries managers rather than environmental/con­ mendation of the Ecologically Sustainable De­ servation departments, but with the current focus velopment (ESD) working group was that on ecosystems, fisheries managers need to reas­ potential impacts be identified so that breaches sess their role-and quickly! It is essential in the of the management plan can be legislated against. aquatic environment that fisheries managers John Koehn urged that priority should be given remain in control of the agenda. to identifiable threats. For example, dams pose Karen Edyvane cautioned the need to put many threats, but are allocated few resources, the issues in perspective when considering other and consequently little management.

36 Bureau of Resource Sciences Proceedings Hugh Cross referred to the stakeholder, tiple use areas is the buffer they give to highly often at the top of the organisation, who allo­ protected areas, for example a fish sanctuary. cates the funds, and who needs to be convinced Ross Winstanley supported Duncan of the value to the community, as well as to Leadbitter on the need for a more assertive ecological and catchment processes. approach by fisheries managers in the marine Rob Lewis wanted to know how we can and coastal planning processes. improve valuation of habitat in economic terms, Kruno Kukolic's experience from the ACT which is always a dilemma for fisheries manag­ planning authority was of two sets of guidelines ers. Without a quantifiable value/figure, there which have been created for the conservation of is a danger of lost credibility in the face of wetlands. These are supplied to consultants figures supplied by developers and engineers, who can incorporate the principles in EIS. as their figures may be shaky but are seen as solid. Jenny Burchmore claimed that 80% of de­ cisions are made by planners, with fisheries Jenny Burchmore's experience was that interests having little input. But fisheries man­ the bio-economic models can be a trap. For agers tend to overlook fish habitat protection in example the value of a fishery is expressed as an their educational programmes. Other Govern­ annual loss in an ESD document, but a sustain­ ment departments are often more of a problem able fishery has an infinite value. than developers, because they lack an under­ Duncan Leadbitter reminded the meeting standing of the issues. One remedy would be that the tools are available for implementing workshops for public works engineers and plan­ habitat management in the form of the EIS ners, and education packages directed at bu­ (Environmental Impact Statement), but the EIS reaucracy. However, the downside of all this doesn't contain much science. What is needed could be that other departments may then want from scientists are appropriate guidelines, es­ to take the initiative from fisheries managers. pecially on pre-impact studies, focussing more Karen Edyvane believed that the best way to on environmental needs than developers' wants. educate planners is to work alongside them in the planning process, and to get the fish habitat Rob Lewis agreed, but the time-line on workers of fisheries departments fully involved. EIS's is a constraint. Karen Edyvane was con­ cerned that because drawing up of an EIS is the John Glaister wasn't opposed to the vari­ responsibility of one agency, fisheries manag­ ous stakeholders being involved in the manage­ ers get little input. An integrated approach is ment process. However, the fact that fisheries needed towards looking after the environment, researchers are the source of information on fish and we shouldn't be too negative about strate­ habitat seems to have become devalued cur­ gic planning, with recommendations and guide­ rency. Rather than creating larger bureaucra­ lines at a higher level. Predictive modelling and cies to deal with issues germane to fisheries simulation modelling can be important tools. research, we need to re-establish our impor­ tance as the data source. Terry Walker had difficulty with the con­ Rob Lewis's summary of the discussion of cept of marine parks, where the complex issues cause public confusion, often because they are Session 2 was that the information supplied to set up with inadequate information. When man­ fisheries managers should be improved, there should be a more integrated perspective, there is agers try to accommodate everybody, the out­ a need for resources, a need to identify all come becomes irrational. relevant groups, including other government Karen Edyvane stressed that it wasn't an instrumentalities, and a need to coordinate like easy process. The value of large regional mul- interests.

Bureau of Resource Sciences Proceedings 37 38 Bureau of Resource Sciences Proceedings SESSION 3

ORGANISMS AND ENVIRONMENTAL RELATIONSHIPS I - CASE STUDIES

Session Chairperson: P.C. Gehrke Session Panellists: I.R. Poiner S. Swales M.T.Bales R.M.Morton Rapporteur: G .A. Thorncraft 40 Bureau of Resource Sciences Proceedings CHAIRPERSON'S INTRODUCTION

P.C. Gehrke NSW Fisheries, Inland FisheriesResearch Station PO Box 182 NarranderaNSW 2700

Sustainability has become a buzz word for the gain most in fisheries production from active 1990' s, especially in the context of ecologically sustenance on a cost-benefit basis; (iii) Irrecov­ sustainable development, but what does it mean erably-wounded habitats, on the other hand, are in the context of sustaining both the fishing beyond all hope of economical rehabilitation to industry and fish habitat? My dictionary in­ support fish communities, although social pres­ forms me that to sustain an object or activity is sures to restore the habitat may prevail. These to keep it fromfailing, to endure without giving habitats do not need sustenance, they need to be way, or to support by giving aid. So sustenance rebuilt. means actually doing something to achieve lon­ gevity. Sustaining a fishery, then, ensures that So then, to sustain the habitats upon which the fishery is able to continue into the future, and Australia's fisheriesare based, we do not seek to fisheries management, regulation and research restore modifiedhabitats to their pristine condi­ all contribute to the attainment of that goal. We tion. Nor are we concerned with the irretriev­ are here to discuss how we might sustain fisher­ ably and perhaps repeatedly damaged habitats ies through sustaining fish habitat, which begs which presumably no longer support viable the question of what we mean by sustaining fish fisheries. We are concerned with protecting habitat and how we might actually go about it. nature's family jewels, many of which have some natural protection of their own due to their It is naive to conduct a fishery in a pristine isolation. Mostly though, we are concernedwith habitat and hope the habitat will remain un­ sustaining the walking-wounded habitats, to changed in any way. When additional pressures prevent further damage and where possible, to fromother human activities are imposed upon improve their condition. fish habitats, subtle and not-so-subtle habitat changes become apparent. To borrow an anal­ The interactions between organisms and ogy from military field hospital terminology, their environment are complex, and vary both habitats can categorised on a triage basis with among species and among habitat types. The respect to the severity of their injuries: case studies we will examine in this session (i) Pristine, undamaged habitats are nature's come from shallow coastal habitats, estuaries, crown jewels which only need sustenance in the rivers and lakes, and focuson changes caus�d by form of protection to ensure they are not dam­ natural disasters, impoundment of waterways, aged; (ii) Walking-wounded habitats are those eutrophication and real estate development. that have been damaged in some way, yet still While each of these changes undoubtedly support a component of their original fish com­ impacts upon fisheries, each also has a positive munities. These are the habitats which stand to component which ameliorates the destructive

Bureau of Resource Sciences Proceedings 41 aspects and even provides clear opportunities to recover damaged habitat. The important message shared by these cases is that all activities which change habitats exact a cost in fisheries production, but with attention to details, such as bufferingprocesses and reconstruction, the cost can be reduced and even turnedinto a profit.The challenge for us as researchers and managers is to devise and implement strategies which not only sustain natural habitats, but which in turn sustain our fisheries.

Bureau of Resource Sciences Proceedings 42 MAINTAIN OR MODIFY­ ALTERNATIVE VIEWS OF MANAGING CRITICAL FISHERIES HABITAT

I.R. Poiner, N.R. Loneragan and C.A. Conacher CS/RO Division of Fisheries, Marine Laboratories PO Box 120 Cleveland OLD 4163

Summary fisheries managers need a greater understanding of the factors which determine the carrying Recently fisheries management in Australia has capacity of nursery habitats forjuvenile penaeid shifted to emphasise management of resources prawns, and the factors which limit the within the principles of ecologically sustainable distribution of key fisheries habitats within development. This has resulted in management coastal ecosystems. Fisheries scientists and to sustain fish stocks, maximise economic effi­ managers need to develop the knowledge base ciency when harvesting those stocks, and a and management procedures for the trend towards granting property rights to the implementation of ecosystem management. fishers. To achieve the goal of management to sustain fish stocks, a major focus of fisheries agencies has been to preserve the critical habi­ Introduction tats upon which the long-term productivity of the fisheries depends. For penaeid prawns this The Australian Fishing Zone occupies an area has meant that seagrass (tiger prawns), and 16% larger than the Australian continent. This is mangroves (banana prawns) have achieved spe­ the third largest fishing zone in the world. Com­ cial status to fishers, fisheries biologists, man­ mercial fisheries in this zone were worth ap­ agers and legislators. Is this justified? Is this the proximately A$ l ,200 million in 1991-92 (gross appropriate management strategy to preserve value), of which 80% was exported (Anon 1992). critical fisheries habitat? We examine these This was made up of a diverse array of single questions using two case studies: cyclones, and multispecies fisheries, with over 150 com­ seagrasses and tiger prawns in the Gulf of mercial species. Most of, these fisheries are Carpentaria and king prawns in the Peel-Harvey regional or local, and most stocks are dependent estuarine system in WesternAustralia. upon near shore or coastal nursery habitats. It is clear that a greater understanding of the Recently fisheriesmanagement in Australia key processes operating in the coastal zone is a has shifted to emphasise the management of the critical requirement for fisheries management. resources within the principles of ecotugically It is not enough to just map, monitor and maintain sustainable development. This has resulted in subsets of these systems based on coarse management to sustain fish stocks, maximise distribution and abundance studies of prawn economic efficiency when harvesting those populations. With increasing pressure on the stocks, and a trend towards granting property coastal zone from competing interest groups, rights to the fishers (Anon 1991 ). To achieve the

Bureau of Resource Sciences Proceedings 43 goal of management to sustain fish stocks, a commonly found in seagrass beds (Figure 1) major focus of fisheries agencies has been to (Staples etal. 1985). The seagrasses of the Gulf preserve the critical habitats upon which the of Carpentaria were mapped in 1982, 1983 and long-term productivity of the fisheries depends. 1984. There were approximately 906 km2 of seagrass beds in the Gulf, fringing671 km of For penaeid prawns this has meant that coastline, and consisting of eleven different seagrasses (the critical nursery habitat for tiger seagrass species (Poiner et al. 1987). prawns, Figure 1) and mangroves (the critical nursery habitat for banana prawns, Figure 2) On average five cyclones occur on the have achieved special status to fishers, fisheries Australian coastline each year, although the biologists, managers and legislators; whereas frequency and track vary from year to year. In other key habitats have not received the same 1985 cyclone Sandy approached the coast at the special status e.g. shallow sandy substrates (a Sir Edward Pellew group of Islands. Unlike critical nursery habitat for king prawns, Potter et many cyclones it travelled parallel to the coast, al. 1991). Is this justified? Is this the appropriate and finally crossed north of the Roper River management strategy to preserve critical fisher­ (Poiner et al. 1989). The western Gulf of ies habitat? We examine these questions using Carpentaria, including the area affected by cy­ two case studies: cyclones, seagrasses and tiger clone 'Sandy', had been surveyed by CSIRO in prawns in the Gulf of Carpentaria and king 1984, immediately prior to the cyclone. The prawns in the Peel-Harvey estuarine system in distribution of seagrass beds, their species com­ WesternAustralia. position,density, morphology and biomass were recorded. Following the cyclone, the affected area and nearby 'control' areas unaffected by cyclone Sandy were surveyed annually from Cyclones, seagrasses and prawns­ 1985 to 1990, and then again in 1992. In the last Gulf of Carpentaria four trips the juvenile prawn communities in The Gulf of Carpentaria is a large, rectan­ inshore areas were sampled in the affected and 5 2 gular (approx. 3. 7 x 10 km ), shallow ( <70 m), control areas. tropical embayment between 11-17.5 ° S lati­ In 1985, immediately after the cyclone, the tude and l 36-l 42°E longitude (Rothlisberg and inshore seagrass beds in the area affected by the Jackson 1982). The area has marked seasonality cyclone had disappeared. Seagrass in the deeper in temperature, salinity, rainfall and wind re­ offshore water had been severely disturbed, but gimes (Poiner et al. 1987). Rainfall is restricted still survived. In 1986,there was still no seagrass to the north-western monsoon in summer (De­ inshore and the deep water beds had also disap­ cember to February) and there is a very d1y peared. In all, 183km2,or 18-20%oftheseagrass period from May to October during the south­ in the Gulf of Carpentaria was removed by east trade winds (Poiner et al. 1987). cyclone Sandy (Poiner et al. 1989). Commercial prawn fishing in the Gulf of Recolonisation was first recorded in 1987, two Carpentaria began in the late 1960s and initially years after the cyclone, when a few shallow concentrated on the banana prawn (Penaeus inshore areas were sparsely covered with patches merguiensis de Man) (Somers et al. 1987). of Halodule uninervis (Poiner et al. 1989). By Tiger prawns (Penaeus esculentus Haswell and 1988 about 20% of the area affected by cyclone P. semisulcatus de Haan) are now the most Sandy had been recolonised by seagrass. important component of the catch, with 3000 to Halodule uninervis andHalophila ova/is, which 4000 tonnes caught each year, mostly in the are of little value as habitat for juvenile prawns, WesternGulf (Somers et al. 1987). The juvenile were the predominant species. However a few stages of both species of tiger prawns are most isolated seedlings of the more useful Cymodocea

44 Bureau of Resource Sciences Proceedings serrulata and Syringodium isoetifolium were Thus the severe effect on the juvenile prawn also recorded. In 1989 and 1990 the areal extent habitat and commercial prawn fishery is local­ of seagrass did not change significantly, but ised, and was not reflected in the total commer­ there was an increase in species diversity of cial catch. This begs the question: How much seagrass in the area colonised by C. serrulata seagrass habitat can we lose before there is a and S. isoetifolium. By 1990, an area approxi­ severe effecton the fishery? Juvenile tiger prawn mately 40 km long, south of the Limmen Bight abundance can vary greatly between seagrass River, had still not been recolonised. communities of different types and different tiger prawn species appear to prefer different In the area affected by cyclone Sandy the seagrass habitat types, which probably explains most common juvenile prawns observed in 1989 the relatively small impact of Cyclone Sandy on and 1990 were mostly small non-commercial the annual average catch for the Gulf. species, mainly belonging to the genus Metapenaeus. In contrast, commercially impor­ tant tiger and endeavour prawns were found in the undamaged seagrass beds (Thorogood et al. Peel-Harvey estuarine system 1990). The Peel-Harvey Estuary (lat 32° 35' S, long Log book data and landing statistics from 115° 45 'E) is located 80 km south of Perth and is 1980 to 1991 were analysed to determine whether the largest estuarine system in south-western there was a decline in the catch of tiger prawns Australia, covering a surface area of about 130 2 after the destruction of the seagrass beds. The km • It consists of two shallow (mostly 2 m catch of tiger prawns in the South westernGulf deep) inter-connected basins (Peel Inlet and of Carpentaria fluctuates widely from year to Harvey Estuary) and a short, narrow Entrance year. From 1980 to 1984 the average annual Channel linking the system to the sea (McComb catch of tiger prawns in both the affected and et al. 1981 ). This estuary undergoes large fluc­ unaffected areas was about 250 tonnes tuations in salinity during the winter and spring (Thorogood et a 1. 1990). Since cyclone Sandy in months when approximately 90% of the annual 1985 the annual catch in the unaffectedarea has rainfall is recorded in this region, and much of ranged from100 to 350 tonnes, with an average the Estuary can become hypersaline (up to 50 of 200 tonnes, while the total catch in the af­ ppt) during late summer, early autumn (McComb fected area declined to about 40 tonnes in 1988 et al. 1981; Loneragan et al. 1986). The Peel­ and 1989 (Thorogood et al. 1990), and in 1991 Harvey system supports important commercial was 87 tonnes (Figure 3). That is, the loss and recreational fisheries for a variety of species through the cyclone, of seagrass as a habitat for of fish and crustaceans (Potter et al. 1983; 1991 ). juvenile prawns, may have resulted in a de­ Since the late 1960s, the Peel-Harvey Estu­ crease in the commercial prawn catch in the ary has shown increasing signs of eutrophication fishery immediately offshore of the affected due to the high levels of nutrients in the run-off area of up to 80%, or 160 tonnes. derived fromthe agricultural lands in the catch­ The total catch of tiger prawns in the whole ment of the system. Initially there was a very of the Gulf of Carpentaria also fluctuates widely high biomass of macroalgae, particularly the fromyear to year. The annual catch from1980 goat weed Cladophora montagneana, in the to 1991 in the Gulf was 3,848 tonnes. So the 1970s. However, in the 1980s and early 1990s conjectured loss of 160 tonnes of tiger prawns the biomass of goat weed in the system declined due to the effects of the cyclone is approxi­ dramatically and there have been virtually an­ mately 4% of the annual average catch for the nual blooms of the cyanobacteria Nodularia Gulf, despite an 18-20% loss of seagrass in the spumigena during the summer months (McComb Gulf. et al. 1981; Lukatelich and McComb 1986).

Bureau of Resource Sciences Proceedings 45 The estimated total annual biomass of over, these other species of macroalgae do not Cladophora reached a peak of 26 000 tin 1979 smother the substrate or form as dense and and has been lower than 2 000 t throughout most extensive beds as Cladophora. It would appear of the 1980s and early 1990s (Lukatelich and that although the system is still highly eutrophic McComb, unpublished data). This species cov­ in the 1980s and early 1990s, the recovery of the ers the bottom and in the 1970s formed very sandy nursery grounds of the westernking prawn dense, deep beds which smothered the substrate in the Peel-Harvey Estuary has led to a recovery in large areas of the Peel-Harvey Estuary. The of the commercial catches of this species. large banks of this species and the breakdown of macroalgae in the shallows have caused odour problems forresidents and tourists in the region. Discussion and conclusions A macroalgae harvesting program has been undertaken to remove some of the extensive In the relatively pristine Gulf ofCarpentaria, the beds of macroalgae in an attempt to alleviate site of Australias major tiger and bananaprawn some of this problem. fisheries, a natural decline of around 20% ( 183 km2) of prime seagrass habitat resulted in a 4% (160 t) decline in the total catch of the fishery. Western king prawns, Penaeus A simplistic analysis of the data would latisulcatus suggest the fishery can be sustained despite significant declines in coastal seagrass habitats. Adults of the westernking prawn Penaeus In the highly eutrophic Peel-Harvey Estuary, latisulcatus, are found on sandier substrates in loss of sand substrate through smothering by a the Gulf of Carpentaria and Exmouth Gulf, macroalga (Cladophora montagneana) in the WesternAustralia than tiger prawns (Penn and 1970s, led to a marked decline in catches of Stalker 1979; Somers 1987; Dall et al. 1990). western king prawn (Penaeus latisculatus}. In This species is much sought after by both rec­ the 1980s the system is still highly eutrophic but reational and commercial fishers in the Peel with the decline of the macroalgae and partial Harvey Estuary who catch the large juveniles as recovery of the sand habitat, catches of king they emigrate from the estuary on the ebb tides prawns have recovered. It is clear from both of at night, mainly between March and July of each these studies we do not understand in detail the year (Potter et al. 1991 ). Commercial catch data relationship between prawns and their nursery show that catches in the 1960s were much habitats or the factors that limit the distribution higher than those in the 1970s when Cladophora of habitats themselves. reached very high biomasses in the system (Fig­ ure 4)(Potteretal. 1991 ). Following the decline Without suitable nursery areas, there would in biomass of Cladophora, the commercial be no prawn fisheries. But to protect nursery catches increased greatly in the 1980s (Figure 4) areas and hence the long-term productivity of a (Potter et al. 1991 ). fishery, a fishery manager has to know what it is that needs protecting. What exactly are the nurs­ The marked decline in catches is probably ery habitats and what is it that makes some due to the loss of extensive areas of the sandy habitats more suitable than others? Juvenile substrate, the required nursery habitat of this tiger prawns are most abundant on seagrass species (Penn and Stalker 1979; Dall etal. 1990; beds, and juvenile banana prawns are most Potter et al. 1991). Although the biomass of abundant in mangrove-lined estuaries. Indeed, other species of macroalgae has been high in the in the Northern Prawn Fishery, there is good estuary after 1979, it has not reached the same agreement between the distribution of the main levels as that reached by Cladophora. More- tiger prawn fishing grounds and the distribution

46 Bureau of Resource Sciences Proceedings of coastal seagrasses, and between banana understanding of the ecosystems within which prawns and adjacent mangrove-lined estuaries the target species and their critical habitats are (Staples et al. 1985). However, juvenile tiger located (Anon 1991). prawn abundance can vary greatly between seagrass communities of different types and different tiger prawn species appear to prefer References differentseagrass habitat types. In the case of Anonymous (1991). Ecologically sustainable development banana prawns, no one yet knows whether working groups. Final Report-Fisheries. Australian differenttypes of mangrove communities sup­ Government Publishing Service, Canberra, 202pp. port different population densitiesbut, based on Anonymous (1992). Background Fisheries Statistics. De­ the strong regional variability in commercial partment of Primary Industries and Energy, Canberra. catches, we suspect that this may certainly be Issue No. 6, 1992. the case. Just as importantly, no one yet knows Dall, W., B.J. Hill, P.C. Rothlisberg and D.J. Staples (1990). what limits the distribution of the nursery habi­ The Biology of Penaeidae. Adva11ces i11 Mari11e Biol­ tats themselves . Clearly, it is important for ogy 27. fishery managers to know what the most suit­ Loneragan, N.R., I.C. Potter, R.C.J Lenanton and N. Caputi able nursery habitats are so that they know what ( 1986). Spatial and seasonal differences in the fish to protect; but it is just as important to know fauna of the shallows in a large Australian estuary. what factors make habitats suitable so that Mari11e Biology 92, 575-586. managers might know how to protect them. Lukatelich, R.J. and A.J. M'Comb (1989). Nutrient levels Where these habitats have been impacted and/ and the development of diatom and blue-green algal blooms in a shallow Australian estuary. Journal of or are limiting the productivity of the fishery, Plankto11 Research 8, 597-618. obviously it would also be advantageous to know what factors limit the growth and coloni­ M'Comb, A.J., M.L. Cambridge, H. Kirkman and J. Kuo (1981). Biology of seagrasses. In The Biology of sation of nursery habitat vegetation and hence Australia11 Pla11ts. (Eds: J.S. Pate and A.J. McComb), the distribution of habitats themselves. 258-93. (The University of Western Australia Press, Nedlands). It is clear that a greater understanding of the key processes operating in the coastal zone Penn, J.W. and R.W. Stalker (1979). A daylight sampling net forjuvenile penaeid prawns. Australia11 Journalof is a critical requirement forfisheries manage­ Mari11e and Freshwater Research 26, 287-291. ment. It is not enough to just map, monitor and maintain subsets of these systems based on Poiner, I.R., D. J.Staples and R. Kenyon (1987). Seagrass communities of the Gulf of Carpentaria, Australia. coarse distribution and abundance studies of Australian Journal of Marine and Freshwater Re­ prawn populations. With increasing pressure search 38, 121-31. on the coastal zone from competing interest Poiner, I.R., D.I. Walker and R.G. Coles (1989). Regional groups, fisheries managers need a greater un­ studies-seagrasses of tropical Australia. In: Biology derstanding of the factors which determine the of Seagrasses-A11 Australia11 Perspective (Eds: carrying capacity of nursery habitats for juve­ Larkum, A.W.D., A.J. McComb and S.A. Shepherd), nile penaeid prawns, and the factorswhich limit 279-303. (Elsevier, Amsterdam). the distribution of the key fisheries habitats Potter, I.C, R.J.G Manning and N.R. Loneragan (1991). within coastal ecosystems. Fisheries scientists Size, movements, distribution and gonadal stage of and managers need to develop the knowledge the western king prawn (Pe11aeus latisulcatus) in a temperate estuary and local marine waters. Journalof base and management procedures for the im­ Zoology, Lo11do11 223, 419-445. plementation of ecosystem management. We Potter, I.C., N.R. Loneragan, R.C.J Lenanton, P.J. Chrystal need to broaden our focusfrom the commercial and C.J. Grant (1983). Abundance, distribution and industry and the populations of the target spe­ age structure of fish populations in a westernAustral­ cies and their critical habitats to a better ian estuary. Journal of Zoology, Lo11do11 200, 21-50.

Bureau of Resource Sciences Proceedings 47 Rothlisberg, P. C. and CJ. Jackson (1982). Temporal and spatial variation of plankton abundance in the Gulf of Carpentaria, Australia 1975-1977. Journal of Plank­ Seagrass ton Research 4, 19-40. Algae Somers, I.F. (1987). Sediment type as a factor in the distri­ Mudflat bution of the commercial prawn species of the western Channel Gulf of Carpentaria, Australia. Australian Journal of Mangrove Marine and Freshwater Research 38, 133-149. Somers, I.F., PJ. Crocos and BJ. Hill (1987). Distribution 0 40 60 80 100 and abundance of the Tiger Prawns Penaeus esculentus 20 and P. semisulcatus in the north-western Gulf of Occurrence (%) Carpentaria, Australia. Australian Journal of Marine Figure 2. Percentage distribution of the catch of and Freshwater Research 38, 63-78. banana prawns (Penaeus merguiensis) in each of five Staples, DJ., DJ. Vance and D. S. Heales (1985). Habitat habitats in the Embley River estuary, Gulf of requirements of juvenile penaeid prawns and their Carpentaria. relationship to offshore fisheries. In P.C. Rothlisberg, BJ. Hill and D.J. Staples (Editors) Second Australian 600 Cyclone Sandy National Prawn Seminar NPS2, Cleveland, Australia. ( - 183 sq km seagrass) 500 l Thorogood, C.A., I.R. Poiner, I.F. Somers and D. Staples Impacted 400 --o---- (1990). Seagrass and cyclones in the western Gulf of � Control ..c 300 Carpentaria, 1989 update. CSIRO Marine Laborato­ ries Information Sheet No. 7, January 1990. 200

100

co 0 (\J (D co 0 (\J co co" co co co Ol Ol Ol Ol Ol Ol Ol Embley Estuary Figure 3. Catch of tiger prawns before and after cyclone Sandy in areas affected (impacted) and areas Seagrass unaffected (control) by the cyclone. Algae ml Brown tiger Mudflat seagrass C/adophora Nodularia II Grooved tiger Channel Mangrove

0 20 40 60 80 100 Occurrence (%) .c Figure 1. Percentage distribution of the catch of u brown (Penaeus esc11/e11t11s) and grooved (P. ro semisu/catus) tiger prawns in each of five habitats in 0 the Embley River estuary, Gulf of Carpentaria.

60 70 80 90 Year Figure 4. Catch of western king prawns (Penaeus latisulcatus) from the Peel-Harvey estuary before any algal blooms, during the blooms ofthemacroalgae Cladophora montagneana and during the summer blooms of the cyanobacteria Nodularia spumigena (redrawn fromPotter et al. 1991).

48 Bureau of Resource Sciences Proceedings REHABILITATION, MITIGATION AND RESTORATION OF FISH HABITAT IN REGULATED RIVERS

S. Swales NSW Fisheries, Fisheries Research Institute P.O. Box 21 CronullaNSW 2230

Abstract of available fish habitat and consequently adversely affect fish survival and abundance The principal factors implicated in the continu­ (Alabaster 1985). The major perturbations to ing decline of inland fisheries throughout the the environment responsible for most loss and world are generally considered to be the reduc­ degradation offishhabitat arise fromthe effects tion in quality and quantity of fish habitat con­ of land and water resource development and ditions through the effects of land and water river management, particularly works such as resource development works. In particular, river river impoundment forwater supply and hydro­ regulation through channelisation, impound­ power generation (Petts 1984). In addition, fish ment, abstraction and other river engineering habitat conditions may be seriously affectedby and management works often has major adverse _ 1ver channelisation for land drainage effects on fish habitat conditions. However, a : improvement and flood alleviation, water wide variety of techniques exists for restoring _ abstraction for crop irrigation,wetland drainage smtable habitat conditions in regulated rivers and removal of aquatic, riparian and floodplain and improving fish abundance and diversity. vegetation as part of river and floodplain For example, instream habitat improvement management (Brookes 1988). These devices such as current deflectors and artificial perturbations may affect physical, chemical cover devices can be used to re-create lost and biological aspects offish habitat. In addition habitat features,such as the pool-rifflepattern, to such physical perturbations, inland fisheries while artificial fishways improve habitat acces­ are also affected by a wide range of other sibility in impounded rivers. The provision of chemical and biological perturbations, including suitable environmental flows in regulated rivers water pollution, over-exploitation and is an essential requirement for sustaining fish introduction of non-native species (Cowx in abitat conditions. The use of such techniques ? prep.). m the rehabilitation of inland fisheries is illus­ trated through case-studies in the U.K., Canada Major physical perturbations to the river and Australia. environment associated with impoundment and channelisation often affect both the quality and quantity of fish habitat. The construction of dams and weirs may have a wide range of Perturbations affecting the status of effects on fish habitat, both upstream and inland fisheries downstream of impoundments (Petts 1984). Inland fisheries throughout the world are being The migratory movements of fish populations increasingly impacted by a wide range of human in both upstream and downstream directions activities which reduce the quality and quantity are usually hindered or prevented by channel

Bureau of Resource Sciences Proceedings 49 impoundment. River flow regulation by the seasons, and also between age groups, which impoundment has a variety of effects on must be considered in designing habitat downstream channel morphology, hydrology restoration programmes. and water quality which may modifyfish habitat In the field of habitat restoration the terms conditions (Brooker 1981 ). River mitigation, restoration, rehabilitation and channelisation by channel dredging, widening amelioration are often used interchangeably or straightening may lead to an overall loss of and apparently arbitrarily when discussing available fish habitat and may severely degrade methods for restoring fish habitat in regulated the remaining habitat. Such fundamental habitat rivers. However, different approaches are features as channel meandering and the pool­ available forimproving fish habitat, depending rifflepattern may be severely modified by river on the extent of habitat degradation and whether channel works activities which usually lead to the measures are proactive orreactive. Wherever major reductions in overall habitat diversity possible it is preferable to practice impact (Swales 1982a). mitigation in which the adverse effects of the River regulation activities such as these perturbation are minimised using a proactive often produce major changes in the ecology of approach (analogous to 'preventative' the aquatic environment, and fish populations medicine). This approach is receiving increasing may show marked declines in abundance and attention as the preferred option in river diversity through changes to habitat condi­ conservation and management (see Boon et al. tions, particularly reductions in the quantity 1992). However, there are still many situations and quality of physical habitat features and where a reactive approach to river conservation modifications to the natural flow regime (Petts is the only option to sustain fish habitat in 1984; Swales 1982a). regulated rivers. These techniques will be considered brieflyin the following discussion and illustrated with some overseas case studies. Fish habitat rehabilitation in Habitat restoration involves repairing dam­ regulated rivers age caused by past activities and developments. Environmental compensation is the creation of A wide variety of rehabilitation techniques freshwaterhabitats in order to compensate for exists for mitigating the impacts of human anticipated adverse environmental effects of perturbations to the aquatic environment and proposed developments. Habitat restoration can fish habitat. Within the fields of river and be either passive or active and proactive or fishery management there is a range of reactive, while habitat compensation is gener­ approaches available to improve the physical, ally active and proactive (Cairns 1990). chemical and biological aspects of fish habitat (Gore 1985). Possible measures to improve It is important to define the aim of habitat chemical or biological aspects of fish habitat restoration in regulated rivers since it may not may include pollution control, stocking or be practicable to aim to restore a stream or river biomanipulation. Physical habitat restoration to its pristine condition prior to the disturbance measures may include practices to maintain (Cairns1990). A more practicable aim may be instream flows,riparian and aquatic vegetation, to minimise the loss and degradation of fish habitat diversity, macro-habitat features such habitat in order to maintain a reasonably diverse as the pool-riffle pattern, and also preferred and productive aquatic community. Alterna­ micro-habitat conditions (Wesche 1985). tively, if the area affectedcontains an important Habitat requirements of native fish show recreational fishery it may be more important to considerable variation between species and aim to maximise fish density and biomass.

50 Bureau of Resource Sciences Proceedings Habitat restoration techniques Artificial fishways Physical habitat improvement In addition to habitat improvement techniques, methodology there is also a wide range of techniques available to improve the accessibility of suitable habitat Fish habitat in streams and rivers lost or de­ areas. The construction of dams and weirs often graded by river channel works does recover in considerably limits the availability of suitable time as natural hydrologic processes cause the habitat areas. However, there is now a well channel to readjust to the new conditions, and developed field concerned with the design and recovery processes restore and re-create lost construction of artificial fishways in dams and habitat features. However, the natural recovery weirs which allow the upstream and down­ process is necessarily a long-term process and stream movements of fish. Most fishways take fish habitat in channelised rivers may take many the form of artificial 'fish-ladders' or other fish­ years to recover to a level similar to the pre­ passes which provide a free passageway be­ impact conditions (Swales 1982a). However, tween the lower and upper areas of the the natural recovery process can be accelerated impoundment. Most fish-passes have been con­ considerably through the use ofremedial artifical structed for recreationally and commercially habitat improvement devices which can be used important fishes, particularly salmonid species to improve and modify habitat features. Such of salmon and trout, in the impounded rivers of active measures are generally preferable from the northern hemisphere. In the Murray-Darling an environmental perspective since the goal of River in south-east Australia, however, fish­ habitat restoration is achieved in a shorter time passes installed in several weirs to improve the than it would by relying solely on passive natu­ passage of native fish species have been shown ral recovery processes. In severely degraded to be effective in allowing fish movements in streams, natural morphological and biological the river (Mallen-Cooper 1989). recovery may be a very slow process, typically requiring 10-100 years (Swales 1982a). Structures such as low dams, current de­ Environmental stream flows flectors and artificial cover devices have been The impoundment of streams and rivers using used for many years to improve habitat condi­ dams and weirs, together with water abstraction tions for recreationally important species of for crop irrigation, has the effect of regulating trout and salmon in the streams and rivers of the natural river flow to produce a hydraulic North America and Europe (Wesche 1985). flow regime which is considerably removed However, these devices are now receiving in­ from the natural flow regime beforeriver regu­ creasing use and attention as a means of restor­ lation (Petts 1984). An important aspect of the ing lost or degraded fish habitat in regulated restoration of fish habitat conditions in regu­ rivers (see review in Swales 1989). An increas­ lated rivers is the assessment of suitable instream ing number of studies have documented the flows for fish and other biota. Instream flows successful use of these devices in restoring fish provided for environmental reasons, designed habitat in rivers which have been channelised, to enhance or maintain the habitat for riparian impounded orotherwise impacted by river chan­ and aquatic life, are often referredto as environ­ nel works activities. As a result, it has often been mental flows (Gordon et al. 1992). A wide range possible to partially restore the diversity and of techniques have been developed to assess the abundance of fish populations in impacted areas suitability of stream flows for the survival of of stream or river (e.g. Swales and O'Hara fish and other biota (see reviews in Kinhill 1983). 1988; Gordon et al. 1992).

Bureau of Resource Sciences Proceedings 51 The available techniques fall into three ecosystem processes (Swales 1982a). As a re­ major categories. sult, channelised rivers generally experience major declines in fish abundance and diversity ( 1) Historical discharge methods as a response to the loss of major habitat features These are based largely on historical flow such as the pool-riffle pattern and the overall records and use a fixed proportion of flow decline inhabitat diversity (Swales 1982a; 1989). to provide environmental stream flowrec­ ommendations. They are also referred to as Although habitat conditions in channelised 'rule of thumb' methods since they do not rivers will improve in time through river recov­ involve the collection of field data, e.g. ery processes, studies have shown that natural Tennant or Montana method (Tennant recovery is a long-term process. As part of an 1976). experimental study, attempts were made to ac­ celerate the natural recovery process in a (2) Transect or hydraulic rating methods channelised river in north-west England using These involve the collection of field data at artificial habitat improvement devices. The re­ one or more transects in a stream reach and sponses of the fish community to the habitat the development of relationships between changes associated with the installation of these discharge and other physical habitat vari­ devices was assessed. Habitat improvement ables (e.g. Stalnaker 1980). devices in the fo1m oflow weirs, current deflec­ (3) lnstream habitat simulation methods tors and artificial cover structures were installed These consider not only how physical habi­ in a channelised area of river and were found to tat changes with streamflow but combine be effective in improving fish habitat conditions this information with the habitat prefer­ (Swales 1982b). The low dams and cmTent ences of a given species to determine the deflectors were found to be effective in re­ amount of habitat available over a range of creating habitat features such as the pool-riffle stream flows e.g. Instream Flow Incremen­ pattern, while the cover structures simulated tal Methodology (IFIM) (Bovee 1982). areas of shelter normally associated with river banks. Fish populations in the study section were monitored beforeand after the installation of the Case studies improvement devices and the population den­ a. Habitat restoration in a channelised sity and biomass of the main fish species were river estimated by electrofishing. Following habitat Many lowland rivers in the United Kingdom are improvement, the population densities of dace subject to periodic river engineering and man­ and chub, the two main species present, in­ agement works aimed at increasing channel creased by 75% and 37% respectively, while hydraulic capacity and modifying flow condi­ population biomass increased by 31 % and 25% tions to improve land drainage and alleviate (Swales and O'Hara 1983). Distribution map­ flooding. River channel works such as channel ping studies revealed considerable fish reloca­ realignment, bank regrading and vegetation tion following habitat improvement, with large clearance, dredging of the river bed and clearing concentrations of fish being recorded in the of aquatic weeds and other instream material are vicinity of the improvement structures (Figure frequently undertaken over large sections of 1 ). It was concluded that the improvement pro­ lowland river by river management authorities. gramme was successful in paitially mitigating Such works may have severe effects on the the adverse effects on the fishery of previous quality and quantity of fish habitat and on river land drainage works.

52 Bureau of Resource Sciences Proceedings b. Restoration of off-channel habitats that equivalent habitat be created by the devel­ The streams and rivers of British Columbia, opers to compensate for the loss of stream Canada, are major producers of anadromous channel and pond rearing habitat. As a result, species of salmonid such as rainbow trout several artificial off-channel ponds were con­ (Oncorhynchus mykiss), coho salmon structed and connected to the realigned stream (O.kisutch) and chinook salmon channel to provide an equivalent area of rearing ( 0.ts hawytscha). Such species typically rear in habitat for juvenile salmonids. Monitoring of freshwatersfor several years beforemigrating the ponds shortly after construction showed that to the ocean for adult maturation and develop­ juvenile salmonid species were using the ponds ment. Recent studies in the rivers of British as overwintering habitats and that the ponds Columbia have shown that different speciesof were successful in partially compensating for juvenile salmonid show considerable variation the lost natural habitats (Swales et al. 1986). in their habitat preferences and utilisation. In addition, salmonid species show major sea­ c. Environmental streamflowassessment sonal differences in habitat preferences. For The flow of many streams and rivers in the example, in summer, juvenile coho salmon Murray-Darling river basin in south-east Aus­ generally prefer pool habitats with abundant tralia is regulated by dams or weirs constructed cover, but in autumn and early winter, for water supply, navigation or hydro-power populations migrate from their summer rearing generation. Approximately 75% of all the irri­ areas into tributaries, back-channels, sloughs, gated land in Australia is contained within the ponds and lakes in which they overwinter Murray-Darling basin and numerous storage (Swales et al. 1986; 1988). impoundments have been constructed in the In the Coldwater River, a tributary of the headwaters of eastern tributaries of the Darling Fraser River in interior British Columbia, juve­ River. Water supply for irrigation has resulted nile coho salmon and other salmonid species in major changes to the hydrologic flow regime were foundto utilise off-channel habitats, par­ of most of the rivers in the basin. Flow regula­ ticularly shallow floodplain ponds, as their pre­ tion is thought to be one of the principal factors ferredoverwintering areas (Swales et al. 1986; implicated in recent declines in native fish Swales and Levings 1989). The ponds were populations in the Murray-Darling basin found to contain high population densities of (Cadwallader 1986; Lloyd et al. 1991). overwintering coho salmon (up to 4,000 per A wide range of methodologies exists for hectare) and growth in the ponds appeared to be the assessment of the instream flow require­ faster than in main channel habitats. Habitat ments of fish and other biota in regulated rivers conditions in the ponds were less extreme than (Gordon et al. 1992). However, most of these in the main stream channel. Off-channelponds have been developed and tested overseas and appeared to play a valuable role in the lifecycle may not be suitable foruse in Australian rivers, of coho salmon and other juvenile salmonids where the streamflow regime is generally more (Swales and Levings 1989). unpredictable and variable than in most other As a result of road construction works countries. There is a need for the development along the valley of the Coldwater River, the of a reliable and simple method for recommend­ stream channel was diverted and it was found ing minimum instream flowsto protect aquatic necessary to drain several off-channel ponds. life in Australian streams and rivers which is As a consequence of the policy of 'no net loss' inexpensive, easy to perform and requires lit'tle of fish habitat operated by the Department of or no field investigation (Orth and Leonard Fisheries and Oceans in Canada it was required 1990).

Bureau of Resource Sciences Proceedings 53 In New South Wales, the Department of habitat conditions. In the final analysis, fisheries Fisheries and the Department of Water Re­ in regulated rivers can only be sustained by sources are currently investigating the use of an taking measures which sustain fish habitat. alternativeapproach based on the use of' expert­ panels' to assess streamflow suitability for fish populations and river ecosystem processes. In References this approach, expert-panels are set up consist­ ing of specialists in the fields of fish biology, Alabaster, J.E.S. (Ed.) (1985). Habitat modification and freshwater fisheries. Butterworths, London. river invertebrate ecology and fluvial geomorphology.The flowregime below storages Boon, P.J., P. Calow and G.E. Petts (1992). River Co11se1w1- is experimentally manipulated and a range of tion and Management. Wiley & Sons, Brisbane. discharges released from the storage. The ex­ Bovee, K.D. ( 1982). A Guide to Stream Habitat Analysis pert-panel is then asked to score the suitability using the Instream Flow Incremental Methodology. of each flow release as an environmental flowin Instream Flow Inf. Pap. 12, FWS/OBS-82/26, Office of Biological Service, Fish and Wildlife Service, U.S. which native fish are the primary indicators of Department of the Interior, Washington D.C. environmental quality. Preliminary results of the study suggest that the expert-panel approach Brooker, M.P. (1981). The impact of impoundments on the downstream fisheries and general ecology of rivers. pp potentially has a valid and important role to play 91-152 In, Advances in Applied Biology, Vol. 6. (ed. in environmental streamflow assessments T.H. Coaker), Academic Press, New York. (Swales et al. in prep). Brookes, A. (1988). Channelised Rivers: Perspectives for In general there was a consistent trend at all Environmental Management. John Wiley, Chichester. storages for the expert-panels to prefer the low­ Cadwallader, P.L. (1986). Fish of the Muffay-Darling sys­ est discharge releases as summer flows, the tem. In, The Ecology of River Systems (Eds. B.R. highest discharge releases as winter flows, and Davies & K.F. Walker). The Hague, Junk. intermediate discharges as spring and autumn Cairns, J. ( 1990). Lack of theoretical basis forpredicting rate flows. The expert-panel approach, despite some and pathways of recovery. Environmental Manage­ limitations and drawbacks, is thought to be ment 14, 517-526. potentially a useful tool in instream flow studies Cowx, I.A. (in prep). Rehabilitation of Inland Fisheries. for assessing suitable environmental flows in Proceedings of the Workshop and International Sym­ regulated rivers. posium on the Rehabilitation of Inland Fisheries, Uni­ versity of Hull, April 1992.

Gordon, N.D., T.A. McMahon and B.L. Finlayson (1992). Stream Hydrology: An Introduction j<,r Ecologists. Conclusions Wiley & Sons, Chichester.

Although river management and engineering Gore, J.A. (1985). The Restoration of Rivers and Streams. works such as channelisation and impoundment Butterworths, London. can have wide-ranging adverse effects on inland Kinhill (1988). Techniques for detern1ining environmental fisheries through reductions in the quality and water requirements-review. Technical Report series, quantity of fish habitat, it is nonetheless often Report No. 40, Kinhill Engineers Pty. Ltd, a report to possible to restore and rehabilitate the river the Department of Water Resources, Victoria. environment to mitigate the impacts of river Lloyd, L., J. Puckridge and K.F. Walker (199 I). The signifi­ channel works on fish populations. Wherever cance of fish populations in the Muffay-Darling sys­ possible, however, it is still generally preferable tem and their requirements forsurvival. pp. 86-99 In, Consermtion in the Manage111e111 of the River Murray to be proactive rather than reactive and to imple­ system--111aki11g consermtion count. Proceedings of ment preventative measures to minimise the the Third Fenner Conference on the Environment, adverse effects of river modifications on fish Canberra, September, 1989.

54 Bureau of Resource Sciences Proceedings Mallen-Cooper, M. (1988). Fish passage in the Murray­ Swales, S., R.B. Lauzier and C.D. Levings (1986). Winter Darling basin. pp. 123-137 In, Proceedings of the habitat preferences of juvenile salmonids in two inte­ Workshop on Native Fish Management, Canberra, rior rivers in British Columbia. Canadian Journal of

June 1988. Murray-Darling basin Commission, Can­ Zoology 64, 1506-1514. berra. Swales, S., F. Caron, J.R. Irvine and C.D. Levings (1988). Orth, D.J. and P.M. Leonard (1990). Comparison of dis­ Overwintering habitats of coho salmon (Oncorhynchus charge methods and habitat optimisation for recom­ kisutch) and other juvenile salmonids in the Keogh mending instream flows to protect fish habitat. River system, British Columbia. Canadian Journalof Regulated Rivers Research and Management 5, 129- Zoology 66, 254-261. 138. Swales, S., H. Cross and J.H. Harris (in prep). The use of an Petts, G.E. (1984). Impounded Rivers: Perspectives for 'expert-panel' approach in assessing environmental Ecological Management, John Wiley & Sons, Chich­ flows in regulated rivers in south-east Australia. ester. Tennant, D.L. (1976). Instream flow regimens for fish, Stalnaker, C.B. (1980). Theuseofhabitatstructurepreferenda wildlife, recreation and related environmental re­ for establishing flow regimes necessary for mainte­ sources. Fisheries 1, 6-10. nance of fish habitat. pp. 321-337 In, The Ecolo of gy Wesche, (1985). Stream channel modifications and Regulated Streams (Eds. J. V. Ward and J .A. Stanford), T.A. reclamation structures to enhance fish habitat. pp. Plenum Press, New York. 103-159 In, The Restoration of Rivers and Streams Swales, S. (1982a). Environmental effectsof river channel (ed. J.A. Gore), Butterworth, Boston. works used in land drainage improvement. Journalof Environmental Management 14, 103-126. Swales, S. (1982b). Notes on the construction, installation and environmental effects of habitat improvement structures in a small lowland river in Shropshire. Fisheries Management 13, 1-10. Swales, S. (1988). Fish populations of a small lowland channelised river in England subject to long-term river maintenance and management works. Regulated Rivers Research and Management 2, 493-506. Swales, S. (1989). The use of instream habitat improvement methodology in mitigating the adverse effectsof river regulation on fisheries. pp. 185-209 In, Alternatives in Regulated Rivers Management (J.A. Gore & G.E. Petts, eds.) CRC Press, Boca Ralon, Florida. Swales, S. and C.D. Levings (1989). Role of off-channel ponds in the life-cycleof coho-salmon ( Oncorhynchus kisutch) and other juvenile salmonids in the Coldwater River, British Columbia. Canadian Journalof Fisher­ ies and Aquatic Sciences 46, 232-242. Swales, S. and K. O'Hara, (1980). Instream habitat im­ provement devices and their use in freshwaterfisher­ ies management. Journal of Environmental Management 10, 167-179. Swales, S. and K. O'Hara, (1983). A short-term study of the effects of a habitat improvement programme on the distribution and abundance of fish stocks in a small lowland river in Shropshire. Fisheries Management 14, 135-145.

Bureau of Resource Sciences Proceedings 55 • ■ • ••• Flow .. .. □ 6 6 ... □ .. • - 6 □ • • 6 .. • 6 • ...... 6 .. ■ ••• " •• •

Afler Arlificiol cover

0 ... • . • • Chub • • Dace ■ Rooch defleclor o Perch 6 Gudgeon □ Slane-looch Figure 1. Fish distribution and abundance before and after habitat improvement (from Swales and O'Hara 1983).

56 Bureau of Resource Sciences Proceedings A HABITAT FIT FOR FISH- AN AIM OF BIOMANIPULATION?

M.T. Bales Environmental Studies Unit, Department of Water Resources 10 Valentine Avenue Parramatta NSW 2124

Abstract Background to biomanipulation A recurring problem has been observed Since the mid 1970's, when the term world-wide whereby eutrophication has caused "biomanipulation" was used to describe the an increase in algal biomass and has frequently restructuring of the biological community as an resulted in the occurrence of blue-green algal approach to combating eutrophication (Shapiro blooms. Biomanipulation, the 'top-down' ma­ et al. 1975), there has been considerable re­ nipulation of food chains as a means of reducing search effort throughout the northern hemi­ algal biomass, has been the subject of consider­ sphere to assess and determine the effectiveness able research effort in the northern hemisphere of the technique. With the problems caused by and has been used in a number of cases as a eutrophication increasing over recent decades, means of managing and restoring eutrophic interest in biomanipulation has increased as lakes. Its track record has been variable, a number other, more engineering type, solutions have of successes being countered by examples where proven to have limited success. This culminated the manipulation has failed to have the desired in an international conference entitled result. Some possible reasons for these failures, "Biomanipulation Tool forWater Management" the complexity of the systems, the resistance of (Gulati et al. 1990) at which the current experi­ blue-green algae to grazing and the instability of mental and practical experience of the manipulated fish populations, are discussed. biomanipulation was discussed, and the short­ Particular attention is paid to the latter with the comings in knowledge identified. The original likely responses of fish populations following concept ofbiomanipulation espoused by Shapiro their manipulation being explored. In terms of et al. (1975) was the 'manipulation of the biota the future use ofbiomanipulation in Australia it of lakes and their habitats to facilitate certain is suggested that there are fourkey questions: 1) interactions and results which we as lake users how can the fish manipulation best be achieved? consider beneficial'. The word biomanipulation 2) what are the important buffering mechanisms is now normally used in a more restricted sense ensuring the sustainability of the manipulation? to referto foodweb, or 'top-down', manipula­ 3) how can these buffering mechanisms be tion of a system (Shapiro 1990). In the majority promoted and 4) have we the necessary infor­ of cases the reason formanipulating a system is mation on fish biology, behaviour and ecology to reduce algal biomass, in particular when to determine how best to manipulate the sys­ blue-green algae are a problem. The basic con­ tem?. The importance of the future involvement cept behind all food-web manipulations is sum­ of fisheries scientists in biomanipulation re­ marised in Figure 1. Its success depends upon search and use is stressed. the extent of predation on the zooplankton being

Bureau of Resource Sciences Proceedings 57 reduced, ideally leading to an increase in the zooplankton grazing on phytoplanktonin Mount number of larger-sized individuals which are Bold Reservoir, and demonstrated some reduc­ the most efficient grazers on phytoplanktonand tion in phytoplankton biomass in grazed enclo­ are thus best able to maintain a lower algal sures. Lund ( 1991) used small enclosures to biomass. In the majority of cases the most sig­ assess the impact on the foodweb of mosquito nificant predation pressure exerted on the fish control but concluded that it led to no zooplankton is due to fish. Manipulation of the significant improvement in water quality. To fish population takes two main forms, removal this time there has been no attempt to use of the zooplanktivorousfish resulting in a direct biomanipulation of the food chain as a manage­ reduction in predation on the zooplankton, or ment tool for the restoration of waterbodies in enhancement of the piscivorous fish population Australia. as a means of reducing the zooplanktivorous fish. Examples exist where both approaches, or a combination of the two, have been used in an Biomanipulation-success or failure? attempt to restore whole lakes. For example A number of enclosure experiments have dem­ plankti vorous fish were removed from onstrated an increase in larger zooplankton in Cockshoot Broad, U.K. in an attempt to reduce the absence of planktivorous fish ( e.g. Andersson algal biomass, improve the underwater light et al. 1978) and a reduction in phytoplankton climate and promote the growth of aquatic plants biomass in the presence of more or larger (B. Moss, personal communication). This ap­ zooplankton (e.g. Schoenberg and Carlson proach has also been used at Lake Vaeng, Den­ 1984). These provide strong evidence that mark (Spndergaard et al. 1990). More typically biomanipulation works on a small experimental a combination of the two approaches has been scale, but can it be scaled up to the 'whole lake' used where the existing planktivorous scale?. Evidence from those lakes which have populations are reduced as far aspossible and been manipuliJ.tedis contradictory. In some in­ the piscivorous fish populations are enhanced. stances the effects have been dramatic with Such an approach has been used as a restorative examples of a desired increase in the numbers technique, for example for Lake Zwemlust (Van and/or size of the zooplankton, a decrease in the Donk et al. 1989; 1990a), Lake Bleiswijkse phytoplankton biomass, increased water clar­ Zoom (Meijer et al. 1989) and Lake ity, increased macrophyte growth and an im­ Breukeleveen (Van Donk et al. 1990b) in the provement in the amenity, recreational, aesthetic Netherlands, Lake Frederiksborg Slotss0 and drinking water quality. For example re­ (Riemann et al. 1990) in Denmark, Lake Mosvatn moval of planktivorous and benthivorous fish, (Sanni and Waervagen 1990) in Norway, and and the addition of piscivorous fish to Lake Lake Christina (Hanson and Butler 1990) in the Zwemlust, a small lake (1.5 ha, 1.5m deep) in U.S.A. the Netherlands resulted in a reduction in the In Australia there has been very little work chlorophyll a concentration from in excess of on biomanipulation. Geddes ( 1986) compared 250 µg 1-1 to less than 5 µg1- 1 and eliminated the zooplankton communities in four farm dams, appearance of Microcystis blooms. There was three of which were without fish and one stocked an increase in the number of larger zooplankton with redfin (Percafluviatilis). He demonstrated and an increase in the previously sparse aquatic differences in the species composition, abun­ vegetation (Van Donk era!. 1990a). On a larger dance and size distribution of the zooplankton scale at Lake Christina (1619 ha, 1.25m deep) in community which he attributed to the presence the U.S.A., removal of the fish population, and or absence of fish. Men-ick and Ganf (1988) restocking with a more balanced fish popula­ used enclosures to investigate the effects of tion, resulted in a shift to larger zooplankton

58 Bureau of Resource Sciences Proceedings species, a reduction in chlorophyll a concentra­ and of most interest in the context of this paper, tions, an improvement in water transparency the manipulated fish populations are unstable. and an increase in submerged macrophytes Figure 2 summarises the typical response of fish (Hanson and Butler 1990). populations followingtheir manipulation.Where an attempt is made to remove the In contrast many other attempts to zooplanktivorous fish it is virtually impossible biomanipulate lakes have failed to have the to succeed in removing 100% of the population. desired effect,or the initial improvements have The remaining fish, with an abundance of food been transient. For example in Lake and spawning sites and in the absence of Breukeleveen in the Netherlands( 180 ha, 1.45m piscivorous fish are likely to achieve good breed­ deep) removal of a substantial proportion ing success, resulting in a large number of O+ (60- 70%) of the planktivorous and benthivorous fish which will have a detrimental effect upon fish, the addition of O+ piscivores, and seeding the zooplankton populations, undermining the with large-sized daphnids failed to result in a aim of the manipulation. In the absence of a reduction in the chlorophyll a concentration, significant breeding success such a manipula­ improve the water transparency or increase the tion may succeed, a stable and desirable reduced growthofaquaticplants(VanDonketal.1990b). fish population becoming established.If a 100% fish kill is achieved and the desired changes in the zooplankton and phytoplankton populations occur, the long term stability of the change Why do biomanipulations fail? depends upon the timing and nature of the The reasons for the difficulties encountered in re-establishment of the fish population. Of the making biomanipulations work are complex but three options, a total failure of fish to recolonise perhaps fall into three categories. The basic is unlikely, and although perhaps desirable in food-webinteractions are well understood, hav­ terms of the control of algal problems, is not ing been explored extensively in a large number desirable froma fisheries point of view.Almost of field enclosure and laboratory experiments, certainly fish will recolonise a waterbody within but the overall function of a lake or river system a relatively short period, the key point being is complex and the end result of a manipulation whether it reverts to something similar to the is therefore difficult to predict. This may be original undesirable structure, a new undesir­ particularly true in situations where there are able structure or a desirable fish population. In significantpopulations of invertebrates which a more complex manipulation where the are predators on zooplankton and in turn are fed piscivorous fish populations are enhanced in upon by fish.In such a case, removal of the fish addition to the decrease in the zooplanktivorous population may result in an increase in these fish, there is again a range of possible outcomes. invertebrates, possibly increasing the overall The environmental conditions may be unsuit­ predation pressure on the zooplankton, the re­ able for the piscivores, resulting in a failure of verse of the desired outcome. Secondly, the them to survive, effectively the manipulation algae of greatest concern, the blue-greens, may then being simply a removal of zooplanktivorous be inedible and/or suppress the development of fish, with the potential problems discussed pre­ large-bodied zooplankton (Lampert 1981; Haney viously. Alternatively the piscivores may sur­ 1987).If so, reduction in the predation pressure vive and effectivelycontrol the zooplanktivores, exerted on the zooplankton by the fish is not preventing theirincrease to the point where they going to feed through to a reduction in the undermine the success of the manipulation, or phytoplankton biomass, and may even favour they may survive but fail to control the the development of blue-green algae. Finally, zooplanktivores.

Bureau of Resource Sciences Proceedings 59 Thus we see that fish are a key component The second question is one of the role of determining the success or otherwise of bufferingmechanisms. In the long term, in order biomanipulation. In much previous work on to establish a degree of stability in the system, biomanipulation, fish have been considered a buffering mechanisms are required to prevent 'problem' to be eliminated in order to achieve the new desirable fish populations from revert­ success. If biomanipulation is to be used in ing to their pre-manipulation undesirable state. Australia, there are two approaches we can This may simply involve a change in the species take, either continuing to view the fish as a present. For example a piscivore, previously component of the system which must be re­ absent or only present in small numbers, may act moved, or alternatively considering fish to be as a bufferto the redevelopment of troublesome an integral part of the system, and aiming to populations of zooplanktivores. Another im­ achieve the reduced phytoplankton populations portant buffering mechanism might be the pres­ in tandem with the creation of habitats suitable ence of some kind of refugia for zooplankton, for the maintenance of desirable fish allowing their coexistence with populations. zooplanktivorous fish. Differenttypes ofrefugia were discussed by Shapiro (1990). They in­ This poses four key questions: clude, for example, low light, cool tempera­ 1) How can the initial manipulation of the fish tures, low dissolved oxygen, predator populations best be achieved? inefficiency,macrophytes and physical refuges. In shallow lakes the presence of macrophytes 2) What are the important buffering probably represents the best form of refugia. mechanisms which in the long term will Macrophytes have been shown to act as a refuge allow the coexistence of sustainable and for larger Daplmia, decreasing predation by desirable fish, zooplankton, plants and planktivorous fish (Timms and Moss 198 ). It phytoplankton? 4 was suggested that the presence of macrophytes 3) How can we promote the buffering mecha­ in the Norfolk Broads, U.K. allowed the main­ nisms identified in 2)? tenance of clear water and low phytoplankton biomass in the face of very high nutrient con­ ) Do we know enough about the habitat 4 centrations (Moss et al. 1985). requirements of fish to determine how to manipulate the environment in order to This leads to the third question. If buffering encourage the desired species and mini­ mechanisms are identified which are important mise undesirable species? forthe long term success of a biomanipulation how can they actually be created in the field? The first is largely a practical question of For example if macrophytes are shown to be a how to manipulate the fish population. Physical useful buffering mechanism how can their methods of fish capture are well developed and growth be encouraged. readily usable but not suitable or feasible in all circumstances. Chemical control methods, while Finally if we are going to attempt to ma­ being less expensive and more effective, may nipulate fish populations do we know enough run into public relations and legislative difficul­ about the habitat requirements of Australian ties. More difficult to answer might be the fish to determine how to manipulate the envi­ determination of which piscivorous species are ronment in order to encourage the desired, and suitable for control of zooplanktivorous fish, minimise the undesirable, species? Probably of and knowing what their environmental require­ greatest importance is an understanding of the ments are so that their populations can success­ requirements of a small number of piscivorous fully be enhanced. species, which would be suitable species to

60 Bureau of Resource Sciences Proceedings encourage, and of those zooplanktivorous spe­ Hanson, M.A. and M.G. Butler (1990). Early responses of cies which can be identified as posing the great­ plankton and turbidity to biomanipulation in a shallow prairie lake. Hydrobiologia 317-327. est threat to zooplankton populations. 200/201, Lampert, W. (1981). Inhibitory and toxiceffectsofblue-green algae on Daphnia. lnternationale Revue der gesamten Hydrobiologie 66, 285-298. The future of biomanipulation in Lund, M. (1991). An experimental study of foodweb ma­ Australia nipulation and other strategies to control algal blooms at Lake Monger, Abstract-Australian Society for Over recent times we have observed an increase Limnology 1991 Conference. in the problems associated with eutrophication, Meijer, M.L., A.J.P. Raat and R.W. Doef (1989). Restoration particularly an increase in the occurrence of by biomanipulation of Lake Bleiswijkse Zoom (The blue-green algal blooms. It has to be recognised Netherlands): first results. Hydrobiological Bulletin that no single answer or approach exists which 23, 49-57. can solve all of these problems, but Merrick, CJ. and G.G.Ganf (1988). Effects of zooplankton biomanipulation may represent one important grazing on phytoplankton communities in Mount Bold weapon in overcoming them, either as a Reservoir, South Australia, Using enclosures.Austral­ ian Journal of Marine and Freshwater Research 39, stand-alone technique, or in conjunction with 503-23. other methods such as a reduction in nutrient Moss, B., H.R. Balls and K. Irvine (1985). Management of concentrations. Fish are a central component of the consequences of eutrophication in lowland lakes in the biomanipulation process and it is important England-engineering and biological solutions. pp that fisheries scientists are actively involved in 180-185 In J.W. Lester and P.W.W. Kirk (Eds.), Pro­ biomanipulation research to ensure that the ex­ ceedings International Phosphorus Conference. (SP isting knowledge and expertise on fish biology, Publishers, London). behaviour and ecology is fully utilised and that Riemann, B., K. Christofferson,H.J. Jenson, J.P. Millier, C. the sustainability of fish populations, and the Lindegaard and S. Bosselmann (1990). Ecological consequences of a manual reduction of roach and maintenance, creation or improvement of fish bream in a eutrophic, temperature lake. Hydrobiologia habitat can be integrated within the desired 200/201, 241-250. biomanipulation requirements, rather than fish Sanni, S. and S.B. Wrervagon(1990). Oligotrophication as a again being considered purely as a problem to result of planktivorous fish removal with rotenone in be overcome. the small, eutrophic, Lake Mosvatn, Norway. Hydrobiologia 200/201, 263-274. Shapiro, J (1990). Biomanipulation: the next phase- making it stable. Hydrobiologia 200/201, 13-27. References Shapiro, J, V. Lamarra and M.Lynch (1975). Andersson, G., H. Berggren, G. Cronberg and C. Gelin Biomanipulation: an ecosystem approach to lake resto­ (1978). Effectsof planktivorous and benthivorous fish ration. pp 85-96 In Proceedings of a Symposium on on organisms and water chemistry in eutrophic lakes. Water Quality Management through Biological Hydrobiologia 59, 9-15. Control.(Eds.P.L. Brezonik and J.L. Fox). University of Florida, Gainesville, U.S.A. Geddes, M.C. (1986). Understanding zooplankton commu­ nities in farm dams: the importance of predation. pp. Schoenberg, S.A. and Carlson, R.E. (1984). Direct and 387-401 Inlimnology inAustralia(Eds.P. DeDeckker indirect effects of zooplankton grazing on and W.D. Williams) (CSIRO/Dr W. Junk Publishers). phytoplankton in a hypereutrophic lake. Oikos 42, 291-302. Gulati, R.D., E.H.R.R. Lammens, M.L. Meijer and E. van S�ndergaard, M., E. Jeppesen, E. Mortensen, E. Dall, P. Donk (1990). Biomanipulation Tool for Water Man­ Kristensen and 0. Sortkjaer (1990). Phytoplankton agement. (Kluwer Academic Publishers), 628pp. biomass reduction after planktivorous fish reduction in Haney, J.F. (1987). Field studies on zooplankton­ a shallow, eutrophic lake: a combined effectof reduced cyanobacteria interactions. New Zealand Journal of internal P-loading and increased zooplankton grazing. Marine and Freshwater Research 21, 467-475. Hydrobiologia 200/201, 229-240.

Bureau of Resource Sciences Proceedings 61 Timms, R.M. and B. Moss (1984). Prevention of growth of potentially dense phytoplankton populations by zooplankton grazing, in the presence of zooplanktivorous fish, in a shallow wetland ecosys­ tem. Limnology and Oceanography 29(3), 472-486. Van Donk, E., R.D. Gulati and M.P. Grimm (1989). Food-web manipulation in Lake Zwemlust: positive and negative effects during the first two years. Hydrobiological Bulletin 23, 19-34. Van Donk, E., M.P. Grimm, R.D. Gulati and J.P.G. Klein Breteler (1990a). Whole-lake food-web manipulation as a means to study community interactions in a small ecosystem. Hydrobiologia 200/201, 275-289. Van Donk, E., M.P. Grimm, R.D. Gulati, P.G.M. Heuts, W.A de Kio et and L. van Lierre(1990b ). First attempt to apply whole-lake food-web manipulation on a large scale in the Netherlands. Hydrobiologia 200/201, 291-301.

..: PRE-BIOMANIPULATION � -� )Joie,- 1 many zooplanktivorous fish ""-· � . >-- -.: 2 many phytoplankton > N ., ""< 3 fewzooplankton � 1'( k1I> � � �

Fish population manipulated to decrease zooplanktivores t /. POST-MANIPULATION " r- .; ' "-,i 1 few zooplanlctivorousfish r- 2 reduced phytoplankton " � ' ' 3 more or larger zooplankton ' � '; " �

Figure 1. Changes in zooplankton and phytoplankton populations in a waterbody following biomanipulation involving the elimination or reduction of zooplanktivorous fish.

62 Bureau of Resource Sciences Proceedings Initial undesirable fish popluation r---+ Many zooplanktivorous fish Few piscivorous fish I

Manip tion- rnmoval of existing fish popluation r

Fish population __ ___, Zooplanktivorous fish .____ eliminated populations reduced j

Recolonisation Manipulation- addition Abundant food and !+-­ by fish of piscivores spawning sites, little predation by piscivores

Cond1hons . tunsmta "bl e for the maintenance of the piscivorous fish

I Increased number of piscivorous fish

Conditions suitable _ for maintenance of______, piscivorous+ fish Final desirable fish popluation

Fewer zooplanktivorous fish More piscivorous fish

Figure 2. Likely outcomes following the manipulation of existing fish populations (for explanation see text).

Bureau of Resource Sciences Proceedings 63 ENHANCEMENT OF ESTUARINE HABITATS IN ASSOCIATION WITH DEVELOPMENT

R.M. Morton WBM Oceanics Australia POBox203 Spring HillOLD 4004

Introduction do we design them and how do we assess the contribution of any artificial waterways cre­ Urban development is proceeding rapidly in ated by development to the ecology of the sheltered estuarine and coastal areas of sub­ estuary? Unfortunately, there are very few tropical Australia. This trend is unlikelyto slow. Australian studies on creating fish habitats or Fringing the estuaries there are large areas of examining fish fauna in artificial habitats such agricultural lands that are of low ecological as marinas, canals, or similar developments value, and increasingly these areas are becom­ (Saenger and Mcivor 1974; Morton 1989; ing used for residential development. Most de­ Morton in press; Hair and Bell in press). We velopment scenarios involve the creation of know that it sho'uld be possible to create suit­ canals or lakes because these lands are low­ able conditions for estuarine fauna and to de­ lying and require filling to raise them above sign developments appropriately, but flood/stormsurge levels. This style of develop­ opportunities are only recently becoming avail­ ment is also related to the recent greater demand able as environmental considerations achieve for waterfront tourism areas and recreational greater prominence. amenities such as marinas. The increased popu­ lation residing in estuarine regions results in Larger scale developments or operations waterways being used to a greater extent for offeran opportunity to enhance or create aquatic stormwater disposal, floodwater conveyance and habitat. The amount of money involved in such recreational activities (eg. angling or boating) projects is such that even a small percentage of often leading to a need for dredging operations. the total capital investment can be sufficient to fund the creation of large areas of habitat either There is a need to ensure that, if such associated with the development or in degraded developments and associated requirements are areas externalto the development. considered to be of community benefit, they are undertaken in a manner that not only minimises Habitat enhancement/creation schemes impacts on existing habitats but provides the that can result from large scale development opportunity to create new or additional habitat. include (1) those which represent an integral Conversely, if the developments are judged to part of the development, and (2) works which result in adverse ecological impacts then there are undertaken as compensation for distur­ should be a requirement to compensate by cre­ bance of ecologically important habitats. ating habitat (ie. the "no net loss of estuarine The following discussion describes (i) a productivity principle"). study (Tweed Heads Notional Dredge Plan and The problem is, if we are to require com­ River Management Study) designed to pensatory works or enhancement works, how minimise adverse impacts to aquatic fauna

64 Bureau of Resource Sciences Proceedings resulting fromrequired extensive dredging works The Notional Dredge Plan was designed to and (ii) opportunities to provide additional habitat ensure that the most productive areas of the in conjunction with private waterfront lower Tweed estuary are not directly disturbed. developments. Dredging was restricted fromoccmring in river bank areas shallower than 2.0 m Australian Height Datum (AHD), as vegetation, bird, benthic and fish studies indicate that shallow Specific case studies shoreline areas (particularly bays/inlets) have a (i) Tweed River Plan of Management high ecological value. No seagrass beds would be dredged and buffer distances were defined The lower reaches of the Tweed River on the around mangrove, seagrass, commercial net Queensland/NSW border have been shoaling hauling grounds and oyster leases areas. Em­ over the past two decades, primarily as a result phasis has been placed on avoiding potential of infilling with oceanic sand, and this trend is future adverse erosion/scouring processes within expected to continue. There is a need to dredge the estuary which could require remedial dredg­ some areas of the estuary to overcome significant ing operations. Dredging schedules were de­ navigation, flooding and potential water quality signed to minimise and "stagger" alterations to problems. For example, the entrance sand bar is the tidal regime of the estuary, whilst recognis­ very shallow, substantially affectingnavigation, ing the beneficial aspects of dredging. and could force the 25 trawlers based at Tweed Heads to abandon the port. Periodic flooding The Notional Dredge Plan included de­ often causes significant damage to developed signs to enhance dredged and existing habitats areas fringing the Tweed River. The dredging as well as options to create new habitat to benefit works would need to be extensive, and could the ecology and fisheries of the Tweed River. result in the extraction of several million m3 of Funds for such works would result mostly from sand. If the sand could be sold, from$7 million royalties arising from the sale ofextracted sands. to $24 million could be raised in royalties Dredging depths, as defined by the Plan, depending upon the extent of dredging. would not be uniform but would be contoured to WBM Oceanics was commissioned to col­ provide habitat diversity. In some reaches of the laborate with the New South Wales Public Works river, several deep holes (to -9 m AHD) were Department to devise a Notional Dredge Plan to included (Figure I) to provide suitable habitat undertake necessary dredging (which forms part for large pelagic fish and thus enhance angling of the River Plan of Management). A primary in these locations. Dredging of the Tweed River aim of the Notional Dredge Plan is to ensure that entrance is likely to increase the occurrence of dredging works and associated environmental pelagic and reef dwelling fishes in the estuary compensatory/enhancement measures result in because access for these oceanic species will be a net improvement in the overall ecological easier. The Plan therefore has proposed to place well being of the Tweed River estuary. artificial reefs in some areas (Figure 2) to pro­ vide habitat suitable to "attract" fish and provide The major ecological concernin regard to additional angling opportunities forrecreational required dredging relates to hydraulic changes fishermen. Computer modelling studies were resulting from dredging works which will in­ undertaken to ensure that dredged areas would clude an increase in the tidal range of the lower maintain high water-quality conditions. estuary. Depending on the degree of change, lower low tides could increase the aerial expo­ Dredging strategies would include retention, sure of seagrass beds and perhaps result in and in some cases creation, of shallow sloping seagrass losses. Alternatively, the higher high banks to provide areas for net hauling by tides may increase mangrove extent. commercial fishermen or for seagrass

Bureau of Resource Sciences Proceedings 65 establishment. Anticipated water quality modification of techniques and quantification conditions ( eg. current velocities, substrate type) of substantial impacts where they are unavoid­ in areas created using dredge spoil were able (eg. alterations to the hydraulic regime of computer-modelled to ensure that created the river) and secondly, to verify the need for conditions would be suitable for seagrass and scale of compensatory works ( eg. habitat colonisation or transplantation. creation/enhancement). Monitoring studies would also include created or enhanced habi­ Letitia Spit, part of Fingal Peninsula which tats to validate the success of such works. forms the eastern bank of the lower Tweed River (Figure 3), was identified as being par­ The Lower Tweed River Plan of Manage­ ticularly suitable for habitat creation because ment includes a variety of habitat creation/ most of the area concerned is Crown Land enhancement schemes of a magnitude that could isolated fromdensely populated urban areas by only be achieved as a result of a large scale the Tweed River. The Spit has important rec­ operation. These options could be funded as a reational values but presently mostly supports result of dredging royalties with no cost to the degraded vegetation as the area was previously community which would also benefit (eg. in used for sand mining operations. Several tidally terms of flood relief, enhanced recreational connected lagoons (eg. Kerosene Inlet, Figure opportunities and improved navigation) from 3), remnants of previous mining operations, proposed dredging works. were identifiedduring baseline ecological stud­ ies as supporting large areas of seagrass and (ii) Artificial habitats associated with diverse fish/prawn populations. residential development The Tweed River Plan of Management The view that all canal developments provide therefore provides designs (Figure 3) to protect "poor quality habitat" and are detrimental to an these lagoons and create additional similar la­ estuary is generally based upon the perform­ goons to enhance the value of the lower estuary ance of earlier designs. However, the level of to aquatic fauna including species of fisheries planning and design expertise is far greater than importance. Detailed ecological, water quality in the past and there is no reason why a canal or and hydraulic studies of existing lagoons were tidally flushed lake style development cannot completed to assist in the design of proposed be designed to provide habitat suitable for sup­ additional lagoons. Particular emphasis would porting large fish populations of considerable be placed on providing conditions suitable for ecological value. seagrass establishment to compensate for an­ There are several existing canal ticipated seagrass losses occurring as a result of developments that have "accidentally" provided dredging-induced changes in the tidal regime habitat that would otherwise not be available (see above). These works, and associated habi­ within a natural estuary. The author has seen tat enhancement projects (eg. creation of bird large areas of seagrass (Zostera capricorni)in habitat) would be funded fromroyalties result­ residential canal developments at Forster, Port ing from extraction of sands occurring within Macquarie, Yamba and Tweed Heads (NSW), the river and fromLetitia Spit. and numerous other canal developments also Several ecological baseline studies presumably contain seagrass. Some canals (benthos, mangrove and seagrass) have been provide good angling opportunities (Morton in completed and future monitoring studies have press) and large fish often shelter in deeper been designed to enable firstly; the rapid iden­ regions of canals. In many cases, commercial tification of any substantial impacts that may fishermen have netted in canal developments result from proposed dredging, thus enabling (much to the concern of residents fringingthe

66 Bureau of Resource Sciences Proceedings canals) because of the large populations of fish to reduce/prevent elevated sediment loads in present. Floating structures (such as pontoons) storm water runoff.This has lead to the siltation associated with marinas provide a unique non­ of many shallow creeks and bays to the detri­ tidal substrate subject to continual high light ment of the estuary. Properly planned dredging intensity and are often utilised by large numbers can be undertaken to restore waterway depths of juvenile fish(Hair and Bell in press), including and therefore enhance the habitat value of many species of fisheries value. Similarly, there are degraded areas. many examples of mangroves colonising man­ made habitats such as stormwater drains and revetment walls. In some instances mangroves Overview have colonised man-made structures in regions where they would not normally occur and thus Development of many areas fringingestuaries enhanced the region's physical diversity and is inevitable. Large scale development offersan food resources for aquatic fauna. opportunity to plan appropriately and adopt compensatory measures where necessary. In These examples of "accidental" habitats large developments, the scale of capital ex­ demonstrate that habitat of value to fish, such as penditure is such that habitat enhancement, crea­ mangroves or seagrass, can be incorporated into tion and preservation schemes (eg. dedication waterway-orientated residential development. of parks/reserves, creation of artificial wetlands) Mangroves could provide an attractive land­ are a realistic proposition. The piecemeal type scaping/screening feature of many develop­ of smaller scale development offers few such ments. However, mangroves are protected and a opportunities and provides little hope for con­ permit is required to cut or lop mangrove trees. servation of estuarine resources unless long Existing legislation could be modified to protect term Estuarine Management Plans are enacted already established views by allowing the prun­ and reinforced by regional town planning laws. ing/lopping of mangroves (as would be required Basic information is available to define condi­ in such situations) which have been artificially tions required to provide habitat of value to fish established. although there is a need for further studies to Future developments could include design identify the best design attributes of artificial attributes that specifically aim to provide habi­ habitat and how such habitat can be incorpo­ tat for fish, either within the development itself, rated into developments. or in nearby areas specifically dedicated for this purpose. These attributes could form a require­ ment of approving authorities or be included by Acknowledgements the developer to improve the public image of the development. In some instances, man-made I thank the New South Wales Public Works tidally-flushed lakes or canals constructed in Department for permission to use information non-tidal areas may be beneficial to an estuary fromthe Tweed River Plan of Management. Mr in that they provide additional aquatic habitat. Brian Dooley (Public Works Department) pro­ Similarly, a requirement for the creation of vided important guidance and assistance in for­ artificial fish habitat as compensation for the mulation of the Notional Dredge Plan. loss of small areas of natural habitat (eg. as a result of entrance channel requirements) may allow a development to be constructed without adverse ecological effects. For example, previ­ ous urban development of the catchment in many estuaries has not incorporated measures

Bureau of Resource Sciences Proceedings 67 References Hair, C.A. and J.D. Bell (in press). Effects of enhancing pontoons on abundance of fish: Initial experiments in estuaries. Bulletin of Marine Science. Morton, R.M. (1989). Hydrology and fish fauna of canal developments in an intensively modified Australian estuary. Estuarine and Coastal ShelfScience 28, 43- 58. Morton, R.M. (in press). Fish assemblages in residential canal developments near the mouth of a subtropical Queensland estuary. Australian Joumal of Marine and Freshwater Research. Saenger, P. and C.C. Mclvor (1974). Water quality and fish populations in a mangrove estuary modified by resi­ dential canal developments. Proceedings of the /11ter- 11ational Symposium 011 Biology and Management of Mangroves No. 2, 753-765.

Existing -1 m AHD contour New -1 m AHD contour

O 200m DATUM 0.0 AHD

Total quantity of sand removed = 1.2 x l06 m'

Figure 1. Example of part of Tweed River Notional Dredge Plan indicating areas proposed for filling (to create conditions suitable for seagrass establishment) and areas where deep holes will be excavated (to enhance fish abundance).

68 Bureau of Resource Sciences Proceedings MWL

Existing seagrass beds "-----����-

Reduced flow velocities and enhanced water clarity will Artificial reefs to be constructed, encourage seagrass expansion offset from main channel in these areas

Rockw ·------�-MWL / Existing seagrass beds 0 20m LEGEND LE 20m0cA __ Existing depth

·--· Proposed dredged depth NOTE: Scale depth change

Figure 2. Typical schematic cross-section of main Tweed River channel following dredging (NB differing depth scales).

Wetland information z centre 0 500m

LEGEND f.

- New Islands for bird habitats

Figure 3. Conceptual diagram of habitat creation scheme for Letitia Spit (Fingal Peninsula).

Bureau of Resource Sciences Proceedings 69 DISCUSSION OF SESSION 3

Recorded by G.A. Thorncraft FisheriesResearch Institute P.O. Box 21 CronullaNSW 2230

Each presentation fromthe panel was followed promote proactive measures wherever possible, by a brief period for questions, after which the but given the reality of the situation we have to floorwas opened for general discussion. be prepared to have tools available to mitigate impacts of development on fish habitats. Following Ian Poiner' s presentation, Campbell Davies asked how quickly the seagrass George Paras commented to Mick Bales beds recovered after cyclone damage. Ian Poiner that biomanipulation models to establish desir­ replied that recovery of the seagrass beds to their able fish communities were overly simplistic former area may occur in ten years, but recovery because of the complex interactions between of the fisheries was another matter. prey groups at lower trophic levels. Mick Bales Duncan Leadbitter suggested that manage­ replied that this was one of the reasons why it is ment of seagrass beds forprawn fisheries was a difficult to predict the outcome of any classic case of single species management, and biomanipulation exercise with accuracy. asked how a more holistic ecosystem approach Karen Edyvane asked Mick Bales if he had to management may differ?An ecosystem-based thought about modelling physical processes along approach was definitely needed according to with the food web information. He responded Ian Poiner, with the qualifier that a fisheries' that he thought other people had tried it, but he perspective to management should be main­ hadn't modelled physical processes himself. tained to ensure the fishing industry is not disad­ vantaged under an ecosystem approach to Hugh Cross likened the example Rick management. Morton presented to a management experiment and suggested that it is often advantageous to Stan Moberly suggested to Stephen Swales manipulate a system and see how it responds. that rehabilitation was a step in the right direc­ While this example covered the responses of the tion, but that not messing it up in the first place Tweed estuary, he questioned whether there had was preferable. Stephen Swales agreed that been a change in sand distribution either up­ proactive measures are desirable, but depending stream or farther up the coast? Rick Morton on the situation one has to be proactive or answered that there were four components to the reactive. study which addressed water quality; estuarine Murray MacDonald was concerned that flora-fauna; terrestrial flora-fauna; and social habitat restoration was being seen as an approach economics. The social economics study looked that legitimises continuing degradation of habitat at the demand for sand over the long term and and asked whether we ought to be pushing this took into account such things as stock piling sites technique? Stephen Swales agreed that and the impact of extra traffic resulting from restoration was a last resort and that we should sand extraction.

70 Bureau of Resource Sciences Proceedings John Glaister asked whether the study ad­ Murray MacDonald repeated his earlier dressed more northerly habitats which had been concern about using habitat enhancement and degraded by the prevention of sand migrating up restoration as means of legitimising continuing the coast? Rick Morton responded that the entire disturbances of habitats. He asked Rick Morton problem lay in the design of the breakwaters, and ifhe believed that proposals to re-create habitats that sand would continue coming into the Tweed were actually going to come anywhere near estuary until a bypass system was constructed to compensating for the loss in productivity since allow currents to transport sand farther north. the beginning of significant European impact, Until that time, the need for 'remedial' dredging and if not, how can we claim that enhancement of the estuary will continue. The current dredg­ and restoration is actually looking after habitats ing plan assumes that a sand bypass system will in toto and not just a piecemeal effort. Rick be put in and the channels are all dredged to an Morton apologised fornothaving data preceding equilibrium situation so they should not accrete European settlement, but reiterated that the or erode in any areas. Tweed Riverneeds to be dredged to prevent the estuary clogging with sand. While dredging The general discussion started with Jim may not totally compensate for the sand Puckridge commenting that temporal variability intrusion, it was certainly a step in the right was an important issue particular to Australian direction. rivers and was a major factor in structuring fish communities. He asked Stephen Swales about Barbara Richardson asked what follow up approaches to restoring temporal variability to work would be undertaken in the Tweed River the hydrological regime. Stephen Swales replied program, and other similar research programs. that natural variability was a component of the In this case, Rick Morton said it was up to the environmental flow program he was working on NSW Public Works Department to commis­ to design suitable flowregimes for the regulated sion follow up work, however he suggested that rivers in NSW. if a developer is required to put in compensa­ tory works, then there should also be an accom­ Peter Jackson asked Stephen Swales if he panying requirement to monitor them. As an saw value in the concept of having a volume of example, a number of American states require the impoundment allocated to environmental developers to put in compensatory salt marshes, purposes, rather than a minimum flow. The with successful compensation being determined environmental agency responsible for the im­ by a minimum percentage of sprig success and poundment would be able to manipulate its share regeneration. of the water independently of the water manage­ ment agency. Stephen Swales responded that Bob O 'Boyle agreed that when developing NSW Water Resources (DWR) was examining a model, follow up work is essential to find out environmental contingency allowances within if that model really does reflect reality. He its storages. Hugh Cross added that DWR has a commented that the dredging of Halifax Har­ three component environmental flow policy in­ bour uncovered a Pandora's box of heavy met­ cluding an operations component where water is als and other leaching agents in the sediments released fromdams for irrigation, an environ­ and asked Rick Morton whether similar aspects mental contingency component which can act as were addressed in the Tweed estuary. Rick a flush or piggyback release on tributary flows, Morton indicated that there was very little silt and an unregulated flow coroponent. This sys­ associated with the clean oceanic sand that was tem has to be flexible because dams are small entering the estuary, so turbidity plumes and and have an insignificant effect on floodflows related problems were unlikely to occur. How­ for instance, whereas others hardly ever fill ever silt and pesticide analyses were under­ because the dam is too big for the catchment. taken as a precaution.

Bureau of Resource Sciences Proceedings 71 Derek Staples asked Ian Poiner ifhe remem­ possibly have the same ecological value as bered 15 years ago wearing T-shirts reading mangroves that have the tide coming in twice a 'Muddies Need Mangroves', and then question­ day with fish feeding amongst them. Jenny ing whether mud crabs really needed mangroves Burchmore expressed her concernthat this was at all? He then asked if mud crabs still needed a really dangerous area to get into from a man­ mangroves and if so why? Ian Poiner strongly agement perspective, because unless each man­ denied ever wearing those T-shirts for fear of grove stand and seagrass bed in each State is offending Dr Hill, but believed that mud crabs investigated to determine its ecological func­ don't really need mangrove systems. While agree­ tion, these areas need blanket protection to pro­ ing with ecosystem approaches to coastal man­ tect the vitally important areas that we do not yet agement,he thought a much more focused attitude understand. To indicate that some of these areas should be taken to identify the key factors which were less important than others was a very sustain the fishing industry. He believed the dangerous game to play. issue ultimately comes down to questions of allocation between developers and fishermen, Ian Poiner continued the debate by saying and didn't really think the fishing industry was in he would like to see those activities impacting a strong position at this time to win many alloca­ seagrass systems, such as the northern prawn tion battles. fishery, stopped, but couldn't see it happening in the foreseeablefuture because of the question Peter Young expressed concern about the of resource allocation. Rick Mmton agreed and, religious zealotry that seemed to go around every using a mining project as an example, said that time someone said 'habitat'. He also put forward the federal government had decided that the the idea that the ecosystem must be modified to benefits of mining to the Australian community maximise the yield of fish. outweighed the loss of an area of wetland. The Ian Poiner commented that fishery scien­ pragmatic question was then to minimise the tists still do not really understand the couplings impact of mining on wetlands. between fish populations and shallow water Jeremy Prince questioned what people were coastal habitats. He said that it was illogical to actually fighting to maintain. He explained that manipulate a poorly-understood system and in British Columbia, an abalone fishery was somehow 'twiddle' it to maximise a few recently closed down to protect declining stocks populations that have value to the fishery, be­ as a conservation issue. The interesting thing cause that is a very risky strategy. Rob Lewis was that the abalone fishery was only a recent argued that fisheries agencies needed to inte­ development since sea otters, which kept aba­ grate all the issues and considerations involved lone populations in check, had been virtually in traditional fisheries objectives to provide what hunted to extinction in the area before the turnof society expects today. the century. Thus the modern abalone fishery Campbell Davies commented that recent was exploiting a resource which came into be­ work at James Cook University shows there is a ing because sea otters were no longer there. tidal coupling between juvenile reef fish and Now the abalone fishery has been closed down seagrass and mangrove areas. Ian Poiner re­ on conservation grounds, and the sea otters are flected that there is no doubt that mangroves and coming back, abalone stocks appear to be re­ seagrass are important to fisheries, but he would verting to historical background levels. Jeremy be very surprised to find that all seagrasses are Prince's point was that whatever we try to important to those juvenile fish. Rick Morton sustain, we need to be very clear on whether we further remarked that not every mangrove is want to preserve a pristine environment, or important, as some mangroves growing in areas maintain a productive environment for human that are barely touched by the tides couldn't ends?

72 Bureau of Resource Sciences Proceedings SESSION 4

ORGANISMS AND ENVIRONMENTAL RELATIONSHIPS II - KEY VARIABLES AND BROAD BASED ISSUES

Session Chairperson: B.E. Pierce Session Panellists: J.D. Koehn P.C. Young N.R. Loneragan Rapporteur: M.I. Kangas Disccusion of Day 1: D.C. Smith 74 Bureau of Resource Sciences Proceedings CHAIRPERSON'S INTRODUCTION: KEY FACTORS LINKING FISH AND THEIR HABITAT

B.E. Pierce Inland Waters Section South Australian Research & Development Institute GPO Box 1625 Adelaide SA 5001

If we define the habitat of a fish simply as that the fact that we are already dealing with a subset of the environment where it makes its modified system (initiated experiment) in living, it is intuitively obvious that fish most cases; and populations are inextricably linked to the habi­ • limited funding and resources. tat they call "home." People change fish habitat but still want a healthy resource. Therefore, While limited research has been under­ identifying and measuring the key factors link­ taken on specific factors, the relative impor­ ing fish and habitat becomes the cornerstoneof tance of each has not generally been evaluated. management forsustainability (eg, through re­ Ryder and Kerr (1989) have attempted a first search direction, monitoring, regulation and approximation by erecting four over-riding de­ public education). terminants at the environmental level: This conceptually simple linkage process is • dissolved oxygen complicated by (amongst other issues): water temperature • the multivariate nature of both the depend­ subsurface light ent and independent variables (ie, community, fish population, habitat); • dissolved nutrients uncontrollable variability in both the habitat The usefulness of these in non-salmonid and resource; communities has yet to be evaluated at a com­ munity or ecosystem level to predict the impacts • multiple, often unidentified human of anthropogenic habitat change. influences (treatments); time-treatment interactions; Postscript to the workshop • the reactive (as opposed to proactive) nature of monitoring-based assessment; We might have expected a conceptually simple series of outcomes from this session: tentative a lack of clear societal vision/definition of key factors by biotope together with a list of the desired goal (eg, do we want useful methods. In reality, discussions were sustainability of stocks at 50% of natural disparate with no clear "take home message." levels, 25% with some extinctions, 95% Oniy well after the workshop have summary with no extinctions?) formost fishstocks/ threads come together in my mind. I offer the communities; followingpersonal observations:

Bureau of Resource Sciences Proceedings 75 • While there appeared to be consensus go­ digm. Decline trends in many world fisheries ing into the workshop that habitat was criti­ and particularly inland systems seem to indicate cal to fish, it is clear that in no system that the current treatments aren't particularly (freshwater,marine, or estuarine) have we successful. However, as with other paradigm even begun to understand or even closely shifts, habitat/fish linkage may not become evi­ examine the linkages which must suppmt dent until we refocus on habitat management as the associated resources. Put another way, the cornerstone of resource sustainability, for there is a lack of evidence to strongly reject example, as the European Economic Commu­ the null hypothesis of no linkage between nity is initiating (Mader 1991). fish and habitat. While we are good at listing general factors which are likely involved in such presumed References linkage, quantification of most is lacking Mader, H.J. (1991). The isolation of animal and plant nationally and globally. To me it was sur­ populations: Aspects for a European Nature Conser­ prising that relatively few biologists held vation Strategy, 265-275. /11 A. Seitz and V. Loeschcke strong views as to what the key factorswere [Eds.] Species conservation: A populatio11-bio/ogical in their chosen ecosystem. Apparently this approach. Birkhauser Verlag; Basel, 28lpp. research issue is far from the focus of their Ryder, R.A. and S.R. Kerr(l 989). Environmental priorities: thinking. placing habitat in hierarchic perspective, 2-12. /11 C.D. Levings, L.B. Holtby and M.A. Henderson [Eds.] Human habitat impacts appear, based on Proceedings of the National Workshop on effects of current knowledge, to have the greatest habitat alteration on salmonid stocks. Can. Spee. Pub/. treatment effect in limited freshwater sys­ Fish. Aqua/. Sci. 105. tems with progressively less influence Spellerberg, !.F. (1992). Evaluation and assessment for through estuarine systems to coastal and conservation. Ecological guidelines for determining finally pelagic oceanic ecosystems. priorities for nature conservation. Chapman and Hall; London, UK, 260pp. Little consensus exists as to "best" methods Walters, C. (1986). Adaptive management of renewable for this research arena. Multivariate analy­ resources. MacMillan Publishing Company; New sis appears the most rigorous and efficient, York, New York, USA, 374pp. particularly where treatments can be ma­ nipulated in real systems ( eg, Walters 1986; Spellerberg 1992). However, much of the specific information discussed during and after the session fell into the category of "observations" resulting in mental "corre­ lations." Awakening in a cold sweat some days after the workshop, I had a vision of old Chris Columbus pointing an accusing finger at me and calling me a "flat earth biologist" who still insisted that the world rotates around fish, rather than waking up to the reality that fish rotate around their habitat. Perhaps the current fisher­ ies legislation throughout Australia which fo­ cuses primarily on harvest control rather than habitat control is symptomatic of a similar para-

76 Bureau of Resource Sciences Proceedings FRESHWATER FISH HABITATS: KEY FACTORS AND METHODS TO DETERMINE THEM

J. D.Koehn Freshwater Ecology Section Department of Conservation and Natural Resources 123 Brown St. Heidelberg VIC 3084

Introduction Key habitat factors As fish habitat generally remains hidden Key habitat factorsessentially comprise of the underwater, is somewhat foreignto humans as water and its condition, the surrounding land terrestrial beings, andcan be difficultto measure, which helps determine that condition, condi­ it has often been neglected in the study and tions that the water creates within the stream, management of fish species and fisheries. As and instream objects. with terrestrial species however, freshwaterfish species are dependant on the availability of habitat, and it is the alterations to, and destruction 1. Water of, this habitat which are responsible for the Water is the principle component of fish habitat decline in fish species and fisheries that have and whilst much public attention focuses on been witnessed. In general, freshwater fish quality the primary concernmust be the amount appear more dependant on physical habitat than of water that is present. their marine counterparts, as freshwater Quantity ecosystems are more confined by their The amount of water determines the area of the surroundings and are generally under more streambed which is covered (usually measured pressure from environmental changes, due to by wetted area or wetted perimeter) and hence impacts on those surroundings. Although the amount of aquatic habitat available. The changes to stream environments and their amount of habitat area does not necessarily catchments have been well documented in only increase proportionally with flow however, and a few areas (eg. Mitchell 1990), general a combination of particular habitat variables environmental changes have long been which may be deemed as important fora species recognised (eg. Merrick and Schmida 1984; may even decrease as higher flows increase Lake and Marchant 1990) and the causes of water velocities (Tunbridge and Glenane 1988). these changes and threats to fishes fromthem Examples of such changes are given in Figures extensively discussed (Cadwallader 1978; 1 and 2. MDBC 1988; Koehn and O'Connor 1990a; Jackson et al. in press ). It is the changes to the The amount of water can also determine key habitat factors which are responsible for the whether particular habitats actually receive water general decline in fish species. or not, eg. overbank flooding into billabongs.

Bureau of Resource Sciences Proceedings 77 Flow regime affectfeeding (Newcombe and MacDonald The timing of the amount of water in the stream 1991). It can also cause invertebrate drift determines the flow regime. This incorporates (Doeg and Milledge 1991) and ultimately small, short-term variations, large variations smother substrates (Berkman and Rabeni (eg. floods), seasonal variations, the timing of 1987). such variations, and the rate of changes in flow. b) Temperature: Often a forgotten water qual­ Water velocity ity criterion, the water temperature con­ In lotic ecosystems, water velocities are an trols the metabolic rate of the ecosystem important habitat factor. The habits and swim­ and the fish in it. Each species has upper ming capabilities of the species help determine and lower temperature tolerance levels as the preferred water velocity. Variations in ve­ well as specific requirements for activities locity, and shelters from fast velocities pro­ such as spawning (Koehn and O'Connor vided by variations in the substrate, substrate 1990b). particles or other instream objects, are impor­ c) Dissolved oxygen: Suitable levels are es­ tant in providing suitable habitat and refuges sential for respiration. Stream levels can be from other species. Water velocity generally altered by flow and temperature, and by decreases with depth. instream structures such as riffleswhich Depth assist in aeration. Water depth can determine the amount of a d) Salinity: Whilst high levels can preclude paiticular habitat variable (eg. wood debris) freshwater fish from some habitat areas which is available in the water column. Vertical (Anderson and Morison 1989), appropri­ space in the water column is likely to be of ate salinity levels can also be impmtant for greater need to mid-water schooling species those species which have an estuarine or than benthic species. Water depth is an important marine phase to their lifecycle. factor in avoidance of terrestrial predators, and in conjunction with water velocity it determines e) Nutrients : Whilst nutrients are an impor­ the stream habitat type eg. pool or riffle.Depth tant factor in stream production, excessive and velocity gradients provide the major nutrient loads are a major contributing fac­ component for fish microhabitat use in many tor in eutrophication. stream fish assemblages (eg. Grossman et al. Toxins: Can cause death, stress or increased 1987a, b; Angermier 1987). Depth can provide f) abnmmalities. relatively stable, sheltered areas whereas shallow areas are particularly sensitive to There are also a large number of other reductions in water levels. With increasing chemical parameters which may influence the depth, light penetration decreases and hence needs of ce1tain fish species and to which spe­ visibility is reduced, providing protection from cies will have varying tolerance levels or re­ predators. quirements (eg. pH, calcium). Quality All of these water quality parameters can Acceptable water quality is an essential prereq­ be affected by the amount of flow. Reduced uisite for fish habitation and each species has flows can exacerbate toxic effects through re­ different tolerance levels to differentwater qual­ duced dilution. ity parameters (Koehn and O'Connor 1990b). Rivers and streams flow in one direction Some of the major water quality criteria are: and so point source changes to the water quality a) Suspended sediment: Can kill fish at high have the potential to affect the system for large levels, can smother eggs, cause stress and distances downstream.

78 Bureau of Resource Sciences Proceedings Habitat diversity in the form of changes in orientation points around which a territory or depth, velocity, temperatures and other chemical habitat area can be based, spawning sites, and parameters are all important, providing the needs areas in which to hide from predators or hide in of different species and lifestagesand maintain­ wait for prey. Such objects fall into three main ing the heterogeneity of components in the eco­ categories: system. a) Substrate: Substrate particles provide im­ portant refuge areas for small fish and juve­ 2. Surrounding habitat niles whilst substrate undulations provide Catchment particular habitat areas through variation in Catchment management has a major influence depth. on the water quality of the stream and also b) Wood debris: Fallen trees, branches, logs, influences the quantity of water available. Run­ (all usually referredto as snags ), and asso­ off is affected by activities such as urbanisation, ciated organic debris, forma major compo­ drainage, deforestation and reforestation. Any nent of instream habitat, especially in activity in the catchment has the potential to lowland rivers. In addition to providing the affect the stream water. advantages mentioned for instream objects Banks they cause variations in flow and depth, The bank is important as it formsthe perimeter of provide habitat areas and spawning sites for the stream, is the boundary between the water species such as freshwater blackfish and the land, formsthe stream channel and keeps Gadopsis marmoratus (Koehn 1986; Koehn the water within the stream. This helps determine et al. in press; Jackson 1978), and attach­ water depth and velocities, available habitat and ment sites for invertebrates (O'Connor habitat variation. 1991). Riparian zone c) Aquatic plants: Provide habitat and spawn­ This vegetation zone is essential to the well­ ing sites for fish and attachment sites for being of aquatic ecosystems and has continual invertebrates, bed and bank stability and interactions with the stream. It acts as a buffer shade. between the surrounding activities and the stream, As each species has its own particular habi­ filters runoff, provides shade and inputs of or­ tat needs, and these may change throughout its ganic material. In upland streams these inputs lifecycle, a diversity of habitat is essential to provide the major energy source in the form of provide these needs. This diversity is provided leaves, bark etc, and much of the instream habitat in part, by a diversity of other attributes such as (snags, logs, branches) originates fromthis zone. flows. The root systems of this vegetation also play a major role in erosion prevention. Access to habitats Shade For available habitat to be of use it is essential This can be particularly important to those fish that fish species have access to it. Harris (1984) species which avoid sunlight or wish to escape calculated that about 50% of available habitats predators and is also a factor in the prevention of in south-easternNew South Wales and far egst­ algal blooms. em Victoria was not available to migratory species. As about 70% of the fish species in 3. lnstream habitat these coastal drainages need to migrate between Instream objects are important in providing freshwater and the estuaries or the sea at some structure to the underwater habitat. They provide stage of their lifecycles (Koehn and O' Connor shelter from water velocity and sunlight, 1990a), barriers to fish passage mean that a large

Bureau of Resource Sciences Proceedings 79 proportion of the available habitat may not be With a limited number of researchers and available to the majority of fish species in this funds, it is imperative that the best use be made region. Such barriers can be formed by major of the resources available to provide the best structures such as dams, weirs, retarding basins, informationfor managers. This means that be­ etc, or even by less obvious structures such as fore a study is undertaken the most effective poorly designed culverts and road crossings. In method of research must be determined. The addition to species which are known to make first question that must be asked is: What is the large scale migrations, all species need to be required outcome? What is the information able to move freely within the stream in order to needed for? What is the question that we are recolonise and findsuitable habitat areas, mates going to try to answer? Then, subsequent ques­ etc, and there are many species for which move­ tions such as: What degree of resolution do we ment needs are completely unknown. Serious need to answer the question? Is a yes\no answer attention needs to be given to redressing the enough or do we need further details?; what problems of barriers to fish passage as a habitat degree of scientific rigour do we need to achieve?; issue. what are the parameters that need to be meas­ ured?; what parameters can be managed? Other influencing factors These will assist in determining the method There are several other biotic factors such as best suited to answering the question at hand. introduced species, diseases and food supply which can have a major influence on fish populations, and although they can often act Methods independently of the habitat available, their Multiple parameter studies effects can be influenced by it. For example, Wide-scale studies measuring habitat char­ introduced species with wide habitat tolerances acteristics at several rivers within a region such as carp Cyprinus carpio may be advan­ and correlating them with fish distributions taged over native species which have particular and numbers at those sites (eg. Davies requirements where those requirements have 1989). been degraded. Additional stress caused by suboptimal habitats may assist diseases, and • Localised studies using instream sections lack of food supply could well reflect general where habitat characteristics are measured stream habitat degradation. Such factors are and correlated against fish numbers (eg. well canvassed in other publications (Pollard Koehn 1986; Koehn et al. in press). 1989; Morison 1989; Hynes 1970). • Fish position studies which use the instream locations of individual fish determined by site of capture, observation, radiotracking, Methodologies to determine etc. (see Grossman and Freeman 1987; habitat linkages Tyus et al. 1984). This type of study is often used to determine frequencyof use curves There is still an urgent need for appropriate and habitat suitability models (eg. Terrell basic biological information on freshwater fish. 1984). A collation of all biological information on Victorian native freshwater fish (Koehn and All of these methods measure a range of 0 'Connor 1990b), shows that there are many habitat parameters and correlate fish numbers gaps in our knowledge base. In order to manage against these parameters using regression analy­ any species or ecosystem properly, knowledge sis, principle components analysis, etc. (Zar of the ecology of the organisms is essential. 1984; Digby and Kempton 1987).

80 Bureau of Resource Sciences Proceedings Single parameter studies In many cases several of these methods These determine the importance of only one may have to be used together with physiological parameter and may often be undertaken as ex­ informationto piece together the full picture of perimental studies in the field or laboratory, eg. the requirements of the species. It should be

LC50 , tolerance tests (Bacher and O'Brien 1988). remembered that this paper refers to manage­ ment-oriented research that will provide appro·­ Single aspect studies priate answers to management in a time and cost Study one particular aspect of the fish and effective manner. Academic theories and the determine the requirements forthat aspect eg. study of freshwaterprocesses remain important the spawning of freshwater blackfish in the overall understanding of freshwatereco­ G. marmoratus (Jackson 1978). systems and should always be considered when Observations research is being designed and undertaken. Field or laboratory observations may provide answers to simple questions such as the nature of the species, and may give a good indication as Constraints to the direction that the study should take, and When undertaking such research, apart from the methods to be used (Eldon 1969). constraints imposed by resources, there are al­ ways constraints imposed by natural conditions Distributional data which need to be taken into consideration. Some May give general information on the areas that of these relevant to freshwaterstudies are: find­ the species inhabits and may be used in conjunc­ ing appropriate natural or relatively undisturbed tion with other data to indicate areas of usage habitats forstudy sites; obtaining sufficientfish (eg. altitude ranges, barriersovercome). numbers to be statistically viable; the effectsof Monitoring other (possibly introduced) fish species present; Widespread monitoring undertaken for other limitations imposed by the endangered or inac­ purposes may not ideally be suited to obtaining cessible nature of the species; barriers to fish direct habitat linkages. Such monitoring can passage downstream; fishing (legal and illegal); however provide baseline data for the future and chance events (eg. a toxic spill, landslides); may indicate trends of populations. Monitoring differentlife stages of the species or different of this type needs to be planned carefully to habitats used at different times ( eg. at night or obtain maximum benefit from expenditure. during spawning); access to sites; the availabil­ ity of efficient capture methods; river type; Monitoring the outcome of a particular seasonal weather; or site conditions. event can provide direct information as to the effect on fish populations. There is an inherent possibility, however, that events requiring long­ term monitoring (eg. timber harvesting ) may Concluding remarks not occur, funding may not be forthcoming (see It is important that research conducted on the Koehn et al. 1992), or that natural variation or habitat requirements of freshwaterfish species chance events may cloud results. is directed toward the better management of Adaptive management those habitats. It is the alteration to their habitats Manipulation of a 'natural' situation and moni­ that has caused the decline of most species and toring of the effects can provide information on in most cases continues to be of threat (see habitat requirements, for example, the place­ Jackson et a I. in press). These threats need to be ment of rocks in the Ovens River substantially addressed in terms of both research and man­ increased the population of two-spined blackfish agement to prevent further declines in freshwa­ present ( Koehn 1987). ter fish stocks. A positive step toward this is the

Bureau of Resource Sciences Proceedings 81 fish management plan for the Murray-Darling Eldon, G. A. (1969). Observations on growth and behaviour Basin (Lawrence 1991) which recognises and of Galaxiidae in aquariums. Tuatara 17, 34--36. addresses many of these problems in that region, Grossman, G. D. and M. C. Freeman (1987). Microhabitat and similar plans for management and research use in a stream fish assemblage. Jouma/ of Zoology are needed for other river basins. (London) 212, 151-176. Grossman, G. D., A., De Sota, M. C. Freeman and J. Lobon­ Cervia (1987a). Microhabitat use in a Mediterranean riverine fish assemblage. Fishes of the lower Acknowledgements Matarrana. Oecologia 73, 490-500. Thanks to Bill O'Connor and the many other Grossman, G. D., A. De Sota, M. C. Freeman and J. Lobon­ colleagues with whom endless discussions on Cervia (1987b). Microhabitat use in a Mediterranean riverine fish assemblage. Fishes of the upper this topic have taken place, and to Pat O'Leary Matarrana. Oecologia 73, 501-512. who assisted with this manuscript. Harris, J. H. (1984). Impoundment of coastal drainages of south-eastern Australia, and a review of its relevance to fish migrations. Australian Zoologist 21, 235-250. References Hynes, H. B. N. (1970). The Ecology of Ru11ning Waters. Liverpool University Press, 555pp. Anderson, J.R. and A.K. Morison (1989). Environmental flow studies for the Wimmera River, Victoria. Sum­ Jackson, P.D. (1978). Spawning and early development of mary Report. Arthur Rylah Institute for E11viro11me11tal the river blackfish, Gadopsis 111ar111oratus, Richardson Research Tech11ical Report Series No. 78. Department (Gadopsiformes:Gadopsidae), in the McKenzie River, of Conservation, Forests and Lands, Victoria, 70pp. Victoria. Australian Jouma/ of Marine a11d Freshwa­ ter Research 29, 293-298. Angermier, P. L. (1987). Spatiotemporal variation in habitat selection in small Illinois streams. In: Matthews, W. J. Jackson, P. D., J. D. Koehn and R. Wager (this meeting). and Heins, D. C. (eds.). Commu11ity a11d Evolutio11ary Australia's Threatened Fishes. 1992 ASFB Listing. Ecology of North America11 Stream Fishes. University Koehn, J.D. (1986). Approaches to determining flow and of Okalahoma Press, Norman, 52-60. habitat requirements of freshwater native fish in Vic­ Bacher, G. J. and T. A. O'Brien (1988). The sensitivity of toria. In: Campbell, I.C. (ed.) Stream Protection. The Australian freshwater organisms to heavy metals. En­ Manage111e11t of Rivers for !11strea111 Uses. (Chisholm vironment Protection Agency Report, Melbourne, Vic­ Institute of Technology: Melbourne), 95-113. toria. Koehn, J .D. (1987). Artificial habitat increases abundance Berkmann, H. E. and C. F. Rabeni (1987). Effect of siltation of two-spined blackfish Gadopsis bispi11osis in Ovens on stream fish communities. E11viro11me11tal Biology of River, Victoria. Arthur Rylah Institute for Enviro11- Fishes 18, 285-294. 111e11tal Research Tech11ical Report Series No. 56. Department of Conservation, Forests and Lands, Vic­ Cadwallader, P.L. ( 1978). Some causes of the decline in toria, 20pp. range and abundance of native fish in the Murray­ Darling River System. Proceedi11gs of the Royal Soci­ Koehn, J. D. and W. G. O'Connor (1990a). Threats to ety of Victoria 90, 211-224. Victorian freshwater fish. \lictoria11 Naturalist 107, 5-12. Davies, P. E. (1989). Relationships between habitat charac­ teristics and population abundance for Brown trout, Koehn, J.D. and W.G. O'Connor (1990b). Biological !11for- Salmo truffa L., and Blackfish, Gadopsis mannoratus 111atio11 for Management of Native Freshwater Fish in Rich., in Tasmanian streams. Australia11 Joumal of \lictoria. (Government printer: Melbourne), 165pp. Mari11e a11d Freshwater Research 40, 341-59. Koehn, J., T. Doeg and T. Raadik ( 1992). Aquatic Fauna. In: Digby, P. G. N. and R. A. Kempton (1987). Multivariate Squire, E. 0. (ed.). First Interim Report forthe Value Analysis c!fEcological Communities. Chapman and Adding Utilisation System Trial 1989-1991. Dept. Hall, London, 206pp. Conservation and Environment, Victoria. Doeg, T.J. and G. A. Milledge (1991). Effect of experimen­ Koehn, J. D., N. A. O'Connor and P. D. Jackson (in press). tally increasing concentrations of suspended sediment Seasonal and size-related variation in microhabitat on macroinvertebrate drift. Australian Joumal of Ma­ use of a Southern Victorian stream fish assemblage rine and Freshwater Research 42, 519-26. (submitted to Environmental Biology of Fishes).

82 Bureau of Resource Sciences Proceedings Lake, P. S. and R. Marchant (1990). Australian upland 300 A streams: ecological degradation and possible restora­ tion. Proceedings of the Ecological Society of Aus­ tralia 16, 79-91. ]: B 200 Lawrence, B. W. (1991). Fish Managemelll Plan. (Murray­ "' , Darling Basin Commission), 48pp.

Merrick, J. R. and G. E. Schmida (1984). Australian Fresh­ water Fishes. Biology and Management. GriffinPress 100 Ltd., South Australia, 409pp.

Mitchell, P. (1990). The Environmental Condition of Victo­ rian Streams. Dept. of Water Resources, Victoria, o+----,----r-----,----,----,-- 102pp. 100 200 300 400 500 FLOW{MUd) Morison, A.K. (1989). Management of introduced species in the Murray-Darling Basin-a discussion paper. In: Figure 1. Length of wetted perimeterrelated to flow, Proceedings of the Workshop on Native Fish Mallage­ measured across transects at two sites (A & B) on the ment. Canberra 16-17 June 1988. Murray Darling Gellibrand river, Victoria. (from Tunbridge and Basin Commission, 149-161. Glenane 1988). Murray-Darling Basin Commission (MDBC) (1988). Pro­ ceedings of the Workshop on Native Fish Mallage­ ment. Ca/Iberra, 16-17 Ju/le 1988. Murray-Darling Basin Commission, 1989.

Newcombe, C. P. and D. D. MacDonald (1991). Effects of 2400 - - - Total area or stream bed suspended sediments on aquatic ecosystems. North American Joumal of Fisheries Mallagement 11, 72- 2(){X) 82. / O'Connor, N. A. (1991). The effects of habitat complexity I I on the macroinvertebrates colonising wood substrates 1000 I in a lowland stream. Oecologia 85, 504-512. I Pollard, D. A. (ed.) (1989). llltroduced alld trallslocated Fishes a/Id Their Ecological Effects.Australian Soci­ ety for Fish Biology Proceedings No. 8. Australian 100 200 300 400 Government Publishing Service, Canberra, !Sipp.

FLOW(MUd) Terrell, J. W. (ed.) (1984). Proceedings of a workshop on fish habitat suitability index models. U.S. Fish and Figure 2. 'Rearing habitat' for freshwaterblackfish Wildlife Sen•ice Biological Report 85(6), 392pp. Gadopsis marmoratus (defined as water with a depth >45cm and velocity< 30cm/sec) at a range of flows Tunbridge, B.R. and T.J. Glenane (1988). A Study of Ellvi­ ronmelltal Flows Necessary to Maintain Fish at the Mt. McKenzie section of the Gellibrand river, Populations in the Gellibrand River a/ld Estuary. Victoria. (fromTunbridge and Glenane 1988). Arthur Rylah Institute for Environmental Research. Department of Conservation, Forests and Lands, Vic­ toria, !Sipp.

Tyus, H. M. , B. D. Burdick and C. W. McAda (1984). Use of radiotelemetry for obtaining habitat preference data on Colorado squawfish. North American Joumal of Fisheries Mallagemelll 4, 177-180.

Zar, J. H. (1984). Biostatistical a/lalysis. Prentice-Hall, London, 718pp.

Bureau of Resource Sciences Proceedings 83 DEFINING KEY FACTORS RELATING MARINE FISHES AND THEIR HABITATS

P.C. Young1 and J.P. Glaister2 1 CS/RO Fisheries GPO Box 1538 Hobart TAS 7001 2QDPI Fisheries GPOBox46 Brisbane QLD 4001

Introduction in the inshore volume of water and promote vertical mixing thereby reducing stratification. We have already heard about the key factors Thus strong currents across a rough bottom will, relating freshwater and estuarine fishes and through turbulence, mix heated surface waters their habitats and now we turn to the marine and bottom nutrients. Shore boundaries limit environment. The oceans are basins in the surface directions of current flow and allow deposition of the solid earth containing seawater. It is also of sediment loads or scouring by wave action. evident that far more of the earth's surface is covered by sea (71 % ) than land (29%) and that The continental shelf extends from the shore perhaps we should refer to the "Ocean" rather with an average gradient of 1 in 500. Its outer than the Earth! Although the average depth of limit (the shelf-break) is set where the average the oceans is close to 4 km (whilst the seas are gradient increases to about 1 in 20 to form the generally about 1 km), relative to the horizontal continental slope which continues to the deep­ dimensions of the oceans (5,000 to 15,000 km) sea bottom. The Australian shelf occupies an this depth is small. An analogy for relative area of approximately 2.6 million km2 (or ap­ dimensions would be a sheet of lightweight proximately one third of the land mass) and typing paper (Marshall 1979). However three quarters lies in the tropics. South of the there is a great degree of detail and structure in Tropic of Capricorn, the shelf is generally less this relatively thin layer of the marine than 80 km wide, for instance the shelf width off environment. New South Wales is less than 21 km. In the Broadly, the marine envrionment encom­ tropical region, the width exceeds 320 km in the passes the coastal or continental margins, the north and 200 km in the west. The Australian ocean basins, the mid-oceanic ridge systems shelf may be divided into eight regions, each and the pelagic or ocean waters. Oceanographic characterised by its own typical bathymetry, conditions in the coastal areas differ markedly areal development surface features, geological from those in the open sea. Some of the factors and biological structure. Thus the shelves of causing these differences include river runoff, New South Wales and sub-tropical Queensland; tidal currents and the effectsof shore boundaries Bass Strait and Tasmania; SouthernAustralia; on circulation (Pickard 1975). River runoff re­ sub-tropical Western Australia; North-West duces salinity in surface waters, disperses sus­ Australia; Arafura Sea; Gulf of Carpentaria; and pended sediments and alters optical transparency. the tropical shelf of Queensland, may each be Tidal currents can cause large diurnalchanges separately distinguished.

84 Bureau of Resource Sciences Proceedings The continental slope falls an average ver­ Radiant energy fromthe sun reaches the sea tical depth of about 4 km fromthe shelf break to surface directly or as radiation scattered by the the deep-sea bottom but can drop as much as 9 atmosphere. Some of this energy is reflected, the km vertically over a relatively short distance. rest enters the sea surface, is absorbed and raises The material of the continental slope is pre­ the temperature of the water. The outstanding dominantly mud, with some rock outcrops. The thermal feature of the ocean is that there is an slope descends to depths near 2 km before upper warm layer of water, mainly in tropical merging with the gentler gradients (1:100 to and sub-tropical latitudes, floating on a cold 1 :700) of the continental rise and this then ocean. In fact, three quarters of the volume has grades to the deep-sea bottom. Over much of the temperatures between 0° and 6°C and salinities oceans, the continental slopes and rises are between 34.6 and 34.8 ppt. covered with terrigenous or hemipelagic muds, The density of seawater is an important mixtures of pelagic ooze, and debris derived property which allows oceanographers to trace fromthe continents. These muds are coloured the origins, equilibrium levels and movements red, green or black due to varying degrees of of water masses. Density depends upon pressure oxidation of the organic matter (Heezen and as well as salinity and temperature and increases Rawson 1977). The proximity to land and hence by 1 atmosphere (I kg per cm2) each increase in the relatively rich shelf waters has much to do depth of 10 m. Small changes in temperature, with the high content of organic matter in salinity and density cause large scale mixing of terrigenous muds, which in tum is the basis for water masses (Pickard 1963). the comparatively high productivity of benthic life over and on the continental margins. Evaporation, condensation and the release of latent heat cause atmospheric circulation The deep-sea bottom is the most extensive (wind) that in tum cause waves and drive ocean area, depths of 3 to 6 km being found over 76% currents. The wind-driven circulation of the ocean of the ocean basins, with 1 % of greater depth. differs fromthe thermohaline circulation of the The deepest parts of the oceans are referred to as water masses (maintained by the pull of gravity trenches, and most occur in the Pacific Ocean. on denser seawater types that sinks under less Down to about 5 km the ocean basins are cov­ dense water and then flowsalong stratified lev­ ered with calcareous (derived from zooplankton) els of equilibrium). This wind-driven circulation and siliceous (derived from phyto- and consists of currents that flow horizontally in the zooplankton) oozes and at depths greater than 5 upper fewhundred metres of the ocean and as a km, with inorganic "red" clays. consequence of the Coriolis Force, move in a Covering all of this is the ocean water, the direction to the left of the wind direction in the pelagic environment. Seawater is a complex southernhemisphere (Marshall 1979). solution which contains most of the known Within this vast environment are the world's elements. Chloride, sulphate, sodium, magne­ marine animal communities. Thorson (1971) sium and potassium ions make up the principle has estimated that there are about 160,000 spe­ dissolved constituents. The total amount of dis­ cies of marine animals of which 98 per cent are solved material in parts per thousand (ppt) of benthic and 2 per cent pelagic. Only about 5 per seawater is at a minimum (34.5) near the equa­ cent of the total number of marine animals live tor, rises to a maximum (35.8) at about latitude in the deep sea, though the proportion of pelagic 20°S and then decreases to 34.0 or less towards forms is perhaps greater in these depths than in high latitudes. Though the salinity varies, the the shallower areas. The deep and shallow seas proportion of the principal ions is almost con­ are also alike, in that animal lifeis most diverse stant, due to continual mixing and circulation. in the sub-tropical and tropical belts.

Bureau of Resource Sciences Proceedings 85 Whether considering the deepest ocean lead to drastic reduction in biomass of larger depths or the relatively shallow continental zooplankton, especially krill which, if rare, do shelves, the key factors relating marine fishes not swarm; jack mackerel do not school in and their habitats are defined by unique com­ commercial quantities and the fishery fails plexes of physical and biological factors which (Harris et al. 1992). Thus the water masses may constitute the unique environment or ecological define the marine habitat for jack mackerel and niche (Marshall 1979). a similar situation appears to occur with south­ ernbluefin tuna (Tunnus maccoyii).

Pelagic species Deepsea species Young (1992) noted that of the 3,000 species of marine fishes identified fromAustralian waters, The deep-sea environment has already been the feeding ecology of less than 20 species has alluded to, but what of the species that occur been studied in detail. However these results there? Probably, the most well-known Austral­ suggested that marine fish larvae in Australian ian example is the orange roughy (Hoplostethus waters have similar feeding strategies to their atlanticus) which is the target species for a counterparts elsewhere in the world. For exam­ recently developed deepwater trawl fishery in ple, the larvae ofTrachurus species (Jack Mack­ Australia and New Zealand, and more recently erels) eat cladocerans and larval euphausids off in the Rockall Trench off NW Europe. The the coast of Tasmania when they are available orange roughy occurs in waters deeper than (Young and Davis in press) and this has also 1 000m, feeds on luminescent prawns, squid and been reported in the n01thern hemisphere (Atthur fish (Bulman and Koslow 1992), only produces 1976; Sinyukova 1964). Jordan ( 1992) described less than one-tenth the number of eggs as many the oceanographic variability of the east coast of other species of commercial fish and is at least Tasmania and its likely effectson jack mackerel 20 years old at firstspawning (Smith 1991). (Trachurus declivis). Harris et al. (1991) sug­ Spawning occurs once a year in the Antipo­ gested that in this region the local westerly wind des fromlate April to early August and in very stress is moving cold, nutrient rich water from dense aggregations. A principal winter spawn­ the Antarctic coupled with the large-scale, ocea­ ing aggregation occurs off the east coast of nographic circulation, the East Australian Cur­ Tasmania near St. Helens (Smith 1991). The rent, which moved warm, nutrient-poor water eggs are large (2 mm diameter) and are fertilised southwards to produce annual variability in in the water, after which they drift up towards oceanic conditions during La Nifiayears. They the surface and remain planktonic until they concluded that there was a general decline in hatch (Robertson 1991). Duration of the egg nutrients and a resultant decline in algal biomass stage and further larval development is un­ and large zooplankters (euphausiids and salps) known. at this time. Jordan ( 1992) speculated that these changes may have resulted in concomitant Orange roughy are found in the South Pa­ changes in the abundance and distribution of cific with a discrete community of other deep prey and predators ofTrachurus declivis larvae sea fish species which co-occur at similar depths. and horizontal advection of eggs and larvae. Koslow et al. (in press) have shown that similar Any or a combination of these, Jordan argued, species are foundin the deeper parts of the North may have accounted for the 95% reduction Atlantic, but not in the North Pacific. They between years, of larval and egg density of T. suggested that this discontinuous distribution is declivis. The adult distribution is similarly con­ due to differences in the distribution of the trolled by water conditions; reduced nutrients Antarctic Intermediate water mass in which

86 Bureau of Resource Sciences Proceedings they live. This has a significant flux into the chemical (temperature, light, dissolved oxygen, North Atlantic butnotthe North Pacific. Koslow salinity, sediment), community structure (spe­ et al. (in press) postulate that the absence of cies diversity, biomass, population dynamics, orange roughy and its associated fish commu­ eggs and larvae, and genetic variability) and nity fromthe North Pacific is due to their distri­ biological functions (metabolism, reproduction, bution being determined by that of the physical feedingand specialisation). Thus latitudinal dif­ circulation of Antarctic Intermediate water. ferences (high species diversity, lower indi­ vidual species biomass in the tropics) present Another deepwater species, blue grenadier particularly complex fishery management prob­ (Macruronus novaezelandiae), the most abun­ lems with multispecies interactions (Sainsbury dant commercial finfish species in the New 1982). Zealand deepwater fishery, is a serial spawner, releasing multiple batches of eggs in a season A high proportion of tropical organisms (Sullivan 1991). They are highly fecund,with have an extended pelagic phase in their life an average sized female of 90 cm and spawn histories in which they can only be identified as over 1 million eggs in a season (Hurst et al. in occupying generally similar areas to adults on Sullivan 1991). InNewZealand,grenadierspawn parts of the continental shelf and adjacent slope in winternear canyon features. They form dense (Young et al. 1986) and thus events relatively aggregations which disperse offthe bottom at remote from their adult benthic or epibenthic night when spawning occurs, thus positioning habitat may influence survival of larval organ­ the released eggs in mid-water. The planktonic isms in the oceanic environment. Alterations to eggs and larvae are dispersed by currents. Growth oceanic circulation patterns or water quality, for is rapid, with juveniles reaching 27 cm by the example, could have dramatic impacts on re­ end of the first year and mature adults of 60-70 cruitment and hence adult populations (Hatcher cm by 4-5 years. Maximum age is thought to be et al. 1989). 20-25 years. However Bulman and Blaber (1986) and (a) Coral reef species Gunn et al. (1989) have shown that offTasma­ Coral reef ecosystems have been described as nia, blue grenadier undergo a diurnal vertical the oldest, most diverse and complex ecosys­ migration to feed on mesopelagic prey, during tems on the planet (Davies and Montaggioni the night. These themselves undergo a vertical 1985). Much has been written describing pat­ migration in which they move to the surface tern within these ecosystems (e.g. Williams waters during the day, and returnto the midwater 1982; Bradbury and Young 1981), but it is the at night where they formthe prey of blue grena­ understanding of processes and their quantifica­ dier (Young and Blaber 1986). tion, which are likely to provide insights needed for management (Kenchington 1990). At the core is the understanding of processes operating at differentspatial scales and at differenttempo­ Shallow marine species ral scales. For example, the role of pelagic life Hatcher et al. (1989) provide an excellent re­ stages and recruitment-controlling processes in view of the principal research relevant to the population and community dynamics of fish conservation of tropical marine ecosystems (Sale 1980), the role of local disturbance and (coral reef, mangroves, seagrasses). They pro­ larger scale natural disasters and catastrophes vide a comparison (Table 1, pp 342-4) of the on coral reef community structure and whether ways in which shallow, tropical marine ecosys­ processes are operating at the coral head, patch tems differfrom their temperate counterparts at reef, reef platformor reef province spatial scale comparable depths. These include physico- (Doherty 1987).

Bureau of Resource Sciences Proceedings 87 In addition, a range of anthropogenic (hu­ play complex positive or negative behavioural man origin) effects including water pollution interactions with one another. These could be ( sewage, industrial and agricultural runoff, ther­ trophic, competitive or mutualistic relationships mal effluent); turbidityand sedimentation (land and define social structures. A large number of clearing, dredging, construction and mining); factors could then determine one or more fea­ coral removal (mining, dredging, collecting, tures of the observed structure. These could vessel grounding, anchoring) and removal of include limiting resources (food, living space) living organisms (fishing,collecting, inadvert­ predation and other disturbances, and recruit­ ent removal of non-targeted species), combine ment (Sale 1980). to alter available habitat. Coral reef fishes typi­ The availability of topographically-struc­ cally are highly fecund,can be serial spawners tured living space may limit populations of reef and have a long breeding season. They have a fish (Bradbury and Young 1981). The common pelagic larval stage and sometimes the egg is structural types of coral reef include barrier, also pelagic. Thus although the adults may be fringing and pi atformreefs. A generalised outer relatively sedentary, the offspring are highly or barrierreef would include ( after Veron 1986): mobile through dispersal by oceanic currents lower slope (limited coral, usually extensive (Sale 1980). colonies of one species or genus, light limited The mechanisms by which larval fishes and influenced strongly by water clarity, cur­ return to the reef area is uncertain. Most re­ rents and the steepness of the slope); upper searchers have assumed that the trip must be slope (maximum coral species diversity at20 m, largely passive (Leis 1977; Sale 1971) because mixed community not dominated by any one larvae are unable to swim against any but the species or limited by light, rich structure); reef weakest currents. However, they seem unable to front (narrow zone, exposed at low tide, few detect cues to the presence of a reef until they are short stocky corals able to withstand the force of quite close (Sale 1980). Gyres in the lee of the ocean swell); outer reefflats (hammered by islands may concentrate larvae, thereby pre­ surge, highest point of reef and least populated venting their loss (Leis and Miller 1976). Be­ by corals); inner reefflats (differsfrom former cause of this relationship oflarval distribution to in having much loose rubble and only partly this and other patterns of water circulation, consolidated substrate, sand and rubble inter­ Johannes (1978) considered seasonal patterns mixed with solid reef rock covered with few in spawning have arisen as responses to patterns coral species); lagoons (rocky substrates of in­ of water circulation. By contrast with this pas­ ner reef flats eroded leaving a sandy floor, sive dispersion as larvae, once fish returnto the surrounded by reef, good circulation via tidal reef there is usually a marked change in their currents, relatively few corals but, as protected habit in which they become relatively strongly from wave action, may have elaborate forms); site-attached and sedentary for the remainder of back reef slopes (less regular than outer reef their life (Doherty 1987). slopes, with overhangs, caves and deep can­ yons, coral lush on gentle slopes but bare on Once settled, areas of more or less homog­ steep slopes); and inner-reef sea floor (rubble, enous habitat on a reef will contain an assem­ sand or mud, few corals but rich community of blage of fishes with certain characteristics. The other species, subject to terrestrial influences). species richness of such assemblages will largely be a function of its numerical size (unless it is A typical fringing reef would be found large enough to include all species available). around high islands or along the mainland fore­ Similarly the species comprising the assem­ shore and generally have: inner intertidal blage may be expected to exhibit a wide range of mudflats fringed with extensive mangrove food and microhabitat requirements, and dis- swamps (tidally flushed,subject to storms and

88 Bureau of Resource Sciences Proceedings terrestrial runoff,little structural complexity); and prawns in mangrove habitats are an order of outer intertidal mudflats(increasing depth sea­ magnitude greater than in the adjacent nearshore ward, increasing coral cover in the form of habitats. Blaber et al. ( 1989) and Robertson and microatolls, diversity increasing with depth); Duke (1990) similarly demonstrated markedly and the outer slope (the top exposed only at very higher mean biomasses of fishes from man­ low tides,broad bank of massive coral colonies grove creeks, inlets and intertidal mudflats ad­ and species diversity heavily influencedby tur­ jacent to mangroves, than from surrounding bidity (Veron 1986). areas. It is unlikely that trophic relationships alone could account for these differences.Other In addition, solitary platform reefs, corals factors could include greater available living on rocky shores, algal communities, caves and spaces, the exclusion of marine predators via deep water communities also occur, providing theinflowoffreshwater(Blaberetal. 1985),the extensive and diverse marine habitat for fish. As physical barrier to predators provided by man­ with barrier and fringing types, the physical grove roots (Robertson 1988) and sheltering environment (light, wave action, sedimenta­ effects of high turbidity levels (Blaber and tion, salinity, tidal range, food and inorganic Blaber 1980). nutrients, temperature and bathymetry) largely controls community structure. Such structure largely determines marine fish habitat. (c) Seagrass species Seagrass communities are found from the trop­ ics to the sub-polar regions and along with coral (b) Mangrove species reefs and mangrove forests, rank among the Mangrove communities are marine tidal forests, most productive recorded for natural communi­ taxonomically diverse, with structure charac­ ties (Odum 1982). As the structural complexity terised by adaptation to differences in tempera­ of coastal ecosystems has been revealed by ture,soil salinity,frequency of tidal inundation, research, the importance of seagrass has be­ sedimentation, soil chemistry, degree and fre­ come increasingly recognised (Larkin et al. quency of freshwater flow and ground water 1989). Seagrasses provide food and shelter for availability (Hatcher et al. 1989). The role of a variety of plant and animal species, increase mangroves includes the stabilisation of the primary productivity of coastal waters, re­ sediments deposited by physical forces cycle nutrients, stabilise sediments and provide (Robertson and Duke 1987; Blaber et al. 1989) nursery habitat fora range of fish and crustacea and the provision of food,space and shelter to a (among other groups). Seagrass communities range of mangrove-dependent biota (Milward also often occur in proximity to urban (or poten­ 1979). The species offish that rely on mangrove tially urban) areas and anthropogenic events habitats include permanent residents, intermit­ can cause pronounced destruction through rec­ tent visitors and seasonal transients (as eggs, lamation, dredging, modified hydrological re­ larvae,juveniles or adults). Species occurrence gimes (wave action), overgrazing, siltation, varies geographically, and also in relation to eutrophication,mechanical damage (worm dig­ local topography,tidal range, salinity variation ging),point source pollution and modified tidal and turbidity (Saenger et al. 1977). regimes (channelling). Natural disasters (cy­ The importance of mangroves to fish has clones, floods) and cycles (closing of coastal long been a truism amongst ecologists (Boesch lagoons, dugong grazing) are also significant and Turner 1984) and has been demonstrated by (West 1989). Robertson and Duke ( 1987),who sampled juve­ Like mangroves,seagrasses physically sta­ nile fish communities in mangrove, seagrass bilise sediments since leaves and roots provide and mudflat communities in north-east tropical a physical baffleto water flows, allowing parti­ Australia. They showed that the densities of fish cles (and larvae) to settle (Hatcher et al. 1989). •

Bureau of Resource Sciences Proceedings 89 The roots and rhizomes also matt together, areas. Capehait and Hackney (1989) identified binding the paiticles and minimizing erosion. similar differences in salt-marsh habitat. Seagrasses in coarser-particle sediments tend Werneret al. (1983) investigated foraging to have a greater root mass, presumably for costs (through an application of optimal forag­ greater absorption of nutrients in the nutrient­ ing themy) and found that fish could maximise poor, coarser sediments (Wood and Johannes feeding activity through changing habitats. 197 5). Seagrasses also allow chemical exchange Weinstein and Heck (1979) for example, sug­ to the sediments and provide a substrate for gest a major functional differencebetween tropi­ algal epiphytes. cal and temperate seagrass habitats: coral reefs Again like mangroves, seagrasses provide adjacent to tropical seagrass beds provide shel­ shelter and habitat for small fish and juvenile ter and physical complexity not found in tem­ prawns (Young and Wadley 1979; Coles et al. perate beds. However physical ban-iers (islands, 1987). In the Caribbean, predation in seagrass water circulation) may limit this generalisation communities occurs at night when predators (Sogard et al. 1989). leave the shelter of nearby coral reefs to forage However, comparatively few animals con­ over seagrass beds (Phillips and McRoy 1980). sume seagrasses directly. The ones that do, In tropical Australia seagrass meadows domi­ include green turtles (Limpus and Reed 1984), nated by Halophila and Halodule are impor­ dugong (Poiner et al. 1987) and some sea ur­ tant as nursery grounds forseveral commercially chins, surgeonfishes and pan-otfishes (Kirkman important penaeid prawns ( Coles and Lee Long and Young 1981; Hatcher et al. 1989). 1985; Staples et al. 1985; Coles et al. 1987; Seagrasses also provide a substrate for a variety Poiner 1980; Poiner et al. 1987). of epiphytic algae. Orth et al. (1984) estimated production of algal epiphytes attached to seagrass Many species present in seagrass nursery blades approaches 20% of the sea grass produc­ areas as juveniles may move to other habitats tion and that epiphytes are more important as upon reaching a critical length at which the food for associated fauna than are the more seagrass may no longer provide adequate shelter refractory seagrass blades. (Minella and Zimmerman 1983; Pollard 1984). In their review of the literature Orth et al. Seagrass communities generally have been ( 1984) identified a number of factors to explain extensively studied worldwide yet such habitats the high densities of some species in a range of in tropical and temperate Australia have been sea grass beds and in particular, the role of plant compai·atively ignored. Gulf ofCarpentariahabi­ architecture in the vulnerability of prey species tats (Coles and Lee Long 1985; Poiner et al. to predation. They further proposed that 1987), East Coast of Queensland (Co1es et al. predation and competition could account for 1985; Young and Kirkman 197 5; Kirkman 1978; reported differences in seagrass structure and Poiner 1984; Lennon and Luck 1990), New associated fauna! abundance in some of the South Wales and Victoria (Larkin et al. 1989), work they reviewed. Heck and Thoman (1981) South Australia (Neverauskas 1987) and West­ examined how the success rate of predators ern Australia (Silberstein et al. 1986) have been varied with the density of submerged vegetation investigated and more recently the use of satel­ both experimentally and in the field. They lite imagery and Geographical Information Sys­ found that high densities of artificial eelgrass tems (GIS) have enhanced inventory surveys. hindered the success of predators of grass Most such studies have been mainly concerned shrimp. They also found( 1984) as did Heck et with establishing the importance of wetland al. (1989) that vegetated bottoms supported areas to commercial and other fish and prawn higher numbers of decapods than unvegetated species.

90 Bureau of Resource Sciences Proceedings Key factors-A summary What scale or level of complexity is needed? What are the important factors limiting and This review of key factors relating marine fishes controlling? The present threats, given earlier and their habitats has ranged from the deepest to presentations, certainly point to a continuum the shallowest marine waters and their habitats, from most threatened (freshwater) habitats to and through the full range of life history forms least threatened (deep sea) habitats. fromegg to adult. But what is fishhabitat? Most simply, it is where they live. Such areas can be classified, for example using Fry's system of habitat classification,and then through the limit­ ing factors and controlling factors defined for References each habitat type. These factors are physical Arthur, D.K. (1976). Food and feeding of larvae of three and biological and together complexes of these fishes occurring in the California current, Sardinops factors constitute unique fish habitats. sagax,Engraulis mordax, and Trachurus symmetricus. Fishel)' Bulletin, U.S. 74, 517-530.

In this brief overview of a huge topic, we Blaber, S.J .M. and T.G. Blaber (1980). Factors affecting the have attempted to highlight the principal ma­ distribution of juvenile estuarine and inshore fishes. rine fish habitats and some of the important Joumal of Fish Biology 17, 143-62. factors that define them. It is worth noting that Blaber, S.J.M., J.W. Young and M.C. Dunning (1985). there is a gradation in our knowledge base from Community structure and zoogeographic affinities of shallowest to deepest. In other words, because the coastal fishes of the Dampier region of north­ it is easier (and cheaper!) to study a seagrass bed western Australia. Australian Joumal of Marine and in a few metres than the benthos in a few Freshwater Research 36, 247-66. kilometres, we know more about the shallower Blaber, S.J.M., D.J. Brewer and J.P. Salini (1989). Species habitats. But that bias aside, some generalisa­ composition and biomasses of fishes in differenthabi­ tions can perhaps be made regarding marine tats of a tropical northern Australian estuary: their fish habitat. occurrence in the adjoining sea and estuarine depend­ ence. Estuarine, Coastal and ShelfScience 29, 509- We have seen that structural complexity 31. declines from shallow coral reef/mangrove for­ Boesch, D.F. and R.E. Turner (1984). Dependence of fish­ est/seagrass bed to deep sea benthos. So too ery species on salt marshes: the role of food and does comparative productivity. We know that refuge. Esfllaries 7, 460-8. oceanic circulation (wind-driven and Bradbury, R.M. and P.C. Young (1981). The effects of a thermohaline-driven) becomes increasingly major forcing function, wave energy, on a coral reef important with depth in defining fish habitat. ecosystem. Marine Ecology Progress Series 5, 229- We have seen the numbers of species decline 241. with depth and fromlower to higher latitudes. Bulman, C.M. and S.J.M. Blaber (1986). Feeding ecology The impacts of the terrestrial-ocean interface of Macruronus novaezelandae (Hector) (Teleostei: events (runoff, topography and circulation and Merlucciidae) in South-eastern Australia. Australian tides) decreases from shallower to deeper wa­ Jou ma/ ofMarine and Freshwater Research 37, 621- ters. Finally, natural disasters, catastrophes and 39. anthropogenic impacts are probably of more Bulman, C.M. and J.A. Koslow (1992). Diet and food importance in shallower than deeper waters. consumption of a deep sea fish, orange roughy Hoplostethus Atlantirns(Pisces: Trachichthyidae) off It seems that, in terms of the topic of this South-Eastern Australia. Marine Ecology Progress workshop, and in providing managers with Series 82, 115-129. what they need, when relating marine fishes Capehart, A.A. and C.T. Hackney ( 1989). The potential role and their habitats we need to carefully define of roots and rhizomes in structuring salt-marsh benthic the question or risk being lost in complexity. communities. Estuaries 12(2), 119-22.

Bureau of Resource Sciences Proceedings 91 Coles, R.G. and W.J. Lee Long (1985). Juvenile prawn Heck, K.L., K.W. Abel, M.P. Fahay and C.J. Roman (1989). biology and the distribution of seagrass prawn nursery Fishes and decapod crustaceans of Cape Cod eelgrass grounds in the south-easternGulf of Carpentaria. In: meadows: species composition, seasonal abundance P.C. Rothlisberg, B.J. Hill and D.J. Staples patternsand comparisons with unvegetated substrates. (Eds.)(1985). "Second Australian National Prawn Estuaries 12(2), 59-65. Seminar", NPSZ, CSIRO, Cleveland, Australia, pp.55-60. Heezen, B.C. and M. Rawson ( 1977). Influence of abyssal circulation on sedimentary accumulations in space Coles, R.G., W .J. Lee Long and L.C. Squire (1985). Seagrass and time. Marine Geology 23, 173-196. beds and prawn nursery grounds between Cape York and Cairns. QDPI Information Series, QI 850 l 7. Johannes, R.E. ( 1978). Reproductive strategies of coastal marine fishes in the tropics. Environmental Biology of Coles, R.G., W.J. Lee Long, B.A. Squire, L.C. Squire and Fishes 3, 65-84. J.M. Bibby (1987). Distribution of seagrasses and associated juvenile commercial penaeid prawns in Jordan, A.J. (1992). Interannual variability in the oceanog­ north-eastern Queensland waters. Australian Journal raphy of the east coast of Tasmania and its effects on of Marine and Freshwater Research 38, 103-19. Jack Mackerel (Trachums dec/ivis) larvae.In Hancock, D.A. (ed.)(1992). "Larval Biology," Australian Soci­ Davies, P.J. and I. Montaggioni (1985). In Proceedings of ety for Fish Biology Workshop, Hobart, 20 August the Fifth InternationalCoral Ree/Congress (Delesalle, 1991, Bureau of Rural Resources, Proceedings No.15, et al. (eds), Antenne Museum -EPHE, Moorea 3, 95- AGPS, Canberra, 2llpp. 102. Kenchington, R.A. (1990). "Managing Marine Environ­ Doherty, P.J. (1987). Light-traps: useful but selective, de­ ments," Taylor and Francis, New York, 248pp. vices forquantifying the relative abundance of larval fishes. Bulletin of Marine Science 41, 423-3 l. Kirkman, H. (1978). Decline of seagrass in northernareas of Moreton Bay. Aquatic Botany 5, 63-76. Gunn, J.S., B.D. Bruce, D.M. Furlani, R.E. Thresher and S.J.M. Blaber ( 1989). Timing and location of spawn­ Kirkman, H. and P.C. Young (1981). Measurement of heath ing of Blue Grenadier, Macruronus novaezelandiae and echinoderm grazing on Posidonia oceanica (L) (Teleosti: Merlucciidae), in Australian coastal waters. Delile. Aquatic Botany 10, 329-338. Australian Journal ()fMarine and Freshwater Re­ Koslow, J.A., C.M. Bulman and J.M. Lyle (in press). The search 40, 97-l l 2. midslope demersal fish community off South-eastern Harris, G.P., F.B. Griffiths, L.A. Clementson, V. Lyne and Australia. Deep Sea Research. H. Van Der Doe (1991). Seasonal and interannual variability in physical processes, nutrient cycling and Larkum, A.W.D., A.J. McComb and S.A. Shepherd (1989). the structure of the food chain in Tasmania shelf "Biology of Seagrasses: a treatise on the biology of waters. Journal of Plankton Research 13, 109-131. seagrasses with special reference to the Australian region," Elsevier, Amsterdam. HmTis, G.P., F.B. Griffiths and L.A. Clementson (1992). Climate and the fisheries off Tasmania - interactions Leis, J.M. (1977). Systematics and zoogeography of the of physics, food chains and fish in Payne A.S.L., K.H. porcupine fishes (Diodon, Diodontidae, Brink, K.H. Mann and R. Hillborn (eds) (1992) Tetradontiformes), with comments on egg and larval "Benguela Trophic Functioning" South African Jour­ development. Fisheries Bulletin, US 16, 535-567. nal of Marine Science 12, 585-597. Leis, J.M. and J.M. Miller (1976). Offshore distributional Hatcher, B.G., R.E. Johannes and A.I. Robertson (1989). patterns of Hawaiian fish larvae. Marine Biology 36, Review of research relevant to the conservation of 359-67. shallow tropical marine ecosystems. Oceanography Lennon, P. and P. Luck (1990). Seagrass mapping using and Marine Biology Annual Review, 1989, 27, 337- LANDS AT TM Data: a case study in southern 414, Margaret Barnes(ed.), Aberdeen University Press. Queensland. Asian-Pacific Remote Sensing Journal Heck, K.L. and T.A. Thoman (198 l ). Experiments on 2, 1-7. predator-prey habitats in vegetated aquatic habitats. Lim pus, C.J. and P.C. Reed (1 984). The green turtle Chelonia Journalof Experimental Marine Biology and Ecology midas in Queensland. Population structure in a coral 53, 125-34. reef feeding ground. In G. Grigg, R. Shine and H. Heck, K.L. and T.A. Thoman (1984). The nursery role of Ehmann (Eds.) "The Biology of Australasian Frogs seagrass meadows in the upper and lower reaches of and Reptiles," Surrey Beatty and Sons, Australia, the Chesapeake Bay. Estuaries 7(1), 70-92. pp. 53-61.

92 Bureau of Resource Sciences Proceedings Marshall, N.B. (1979). "Developments in Deep-Sea Biol­ Robertson, A.I. and N .C. Duke (1987). Mangroves as nurs­ ogy," Blandford Press, Dorset, 566pp. ery sites: comparisons of the abundance and species composition of fish and crustaceans in mangroves and Milward, N.E. (1979). Mangrove-dependent biota. In B.F. other nearshore habitats in tropical Australia. Mari11e Clough (ed.). "Mangrove Ecosystems in Australia, Biology 96, 193-205. Structure, Function and Management, "Proceedings oftheA11stralianNational Mangrove Workshop, AIMS, Robertson, A.I. and N.C. Duke (1990). Mangrove fish­ April 1979, Books Australia, 302pp. communities in tropical Queensland, Australia: spa­ tial and temporal patterns in densities, biomass and Minella, T.J. and R.J. Zimmerman (1983). Fish predation community structure. Marine Biology 104(3), on juvenile brown shrimp, Penae11s aztec11s Ives: the 369-79. effect of simulated Spartina structure on predation rates. Jo11rnal of Experimental Marine Biology and Robertson, D.A. (1991). The New Zealand Orange Roughy Ecology 72, 211-31. Fishery: an overview. In Abel, K., M. Williams and P. Smith (Eds.)(1991). "Australian and New Zealand Neverauskas, V.P. (1987). Accumulation of periphyton Southern Trawl Fisheries Conference: Issues and biomass on artifical substrates deployed near a sewage Opportunities," B11rea11 of R11ral Reso11rces, Proceed­ sludge outfall in South Australia. Est11arine and Coastal i11gs No.JO, Pirie Printers Sales, Canberra, 266pp. Shelf Science 25, 509-17. Saenger, P., M.M. Specht, R.L. Specht and V.J. Chapman Odum, W.E. (1982). Environmental degradation and the (1977). Mangat and coastal salt-marsh communities tyranny of small decisions. Bioscience 32, 728. in Australasia. In V.J. Chapman (ed.). "Ecosystems of Orth, R.S., K.L. Heck and J. van Montrans (1984). Fauna! the World I. Wet Coastal Ecosystems," Elsevier, communities in seagrass beds: a review of the influ­ Amsterdam, pp293-345. ence of plant structure and prey characteristics on Sainsbury, K.J. (1982). The ecological basis of tropical predator-prey relationships. Est11aries 7(4), 339-50. fisheries management. In Pauly, D. and G.J. Murphy Phillips, R.C. and C.P. McRoy (Eds.)(1980). "Handbook of (Eds.) "Theory and Management of Tropical Fisher­ Seagrass Biology: and Ecosystem Approach," Gar­ ies, pp. 167-78, ICLARM Conference Proceedings 9. land STPM Press, New York, pp.173-98. Sale, P.F. (1971). The reproductive behaviour of the Pickard, G.L. (1963). "Descriptive Physical Oceanogra­ pomacentrid fish Chromis caerule11s. Z. Tierpsychol. phy," Permagon Press, Oxford, 200pp. 29, 156-64.

Pickard, G .L. ( 1975). "Descriptive Physical Oceanography: Sale, P.F. (1980). The ecology of fishes on coral reefs. an Introduction," Permagon Press, Oxford, 2nd Edi­ Oceanography and Marine Biology Ann11al Review, tion, 214pp. 1980 18, 367-421, Harold Barnes (ed.), Aberdeen University Press. Poiner, I.R. (1980). A comparison between species diver­ sity and community flux rates in the macrobenthos of Silberstein, K., A.W. Chiffings and A.J. McComb (1986). an infaunal sand community and a seagrass commu­ The loss of seagrass in Cockburn Sound, Western Australia. III. The effects of epiphytes on productivity nity of Moreton Bay, Queensland. Proceedings of the of Hook. Royal Society ofQ11eensland 91, 21-36. Posidonia a11stra/is Aquatic Botany 24, 355-71. Poiner, I.R. (1984). Interspecific interactions: their role in Sinyukova, V.1. (1964). The feeding of Black Sea structuring multispecific seagrass communities. AES horsemackerel larvae. Monograph 1, 55-82. Trudy Sevastopolbskoi Biologiche Skoi Stansii, pp. 302-325. Poiner, I.R., D.J. Staples and R. Kenyon (1987). Seagrass communities of the Gulf of Carpentaria, Australia. Smith, A.D.M. (1991). As many red fish as live in the sea: Orange Roughy in Australia. Abel, K., M. Williams A11stralianlo11rnalof Marin e and Freshwater Research In and P. Smith (Eds.)(1991). "Australian and New Zea­ 38, 121-31. land Southern Trawl Conference:Issues and Opportu­ Pollard, D.A. (1984). Review of ecological studies on nities,Burea11 ofR11ral Reso11rces, Proceedi11gsNo.I 0, seagrass - fish communities, with particular reference Pirie Printers Sales, Canberra, 266pp. to recent studies in Australia. Aq11atic Botany 18, 3-42. Sogard, S.M., G.V.N. Powell and J.G. Holmquist (1989). Utilisation by fishes of shallow, seagrass-covered Robertson, A.I. (1988). Decomposition of mangrove leaf banks in Florida Bay: I. Species composition and litter in tropical Australia. Jo11rnal of Experimental spatial heterogeneity. Environmental Biology ofFishes Mari11e Biology a11d Ecology 116, 235-47. 24(1), 53-65.

Bureau of Resource Sciences Proceedings 93 Staples, D.J., D.J. Vance and D.S. Heales (1985). Habitat Young, J.W. (1992). Feeding ecology of marine fish larvae: requirements of juvenile penaeid prawns and their an Australian perspective In Hancock, D.A. relationship to offshore fisheries.In: P.C. Rothlisberg, (ed.)( 1992). "Larval Biology," Australian Society for B.J. Hill and D.J. Staples (Eds.)(1985). "Second Aus­ Fish Biology Workshop, Hobart, 20 August I99I, tralian National Prawn Seminar," NPSZ, CSIRO, Bureau ofRuralResources, Proceedings No.I 5, AGPS, Clevaland, Australia, pp.47-54. Canberra, 211pp. Sillivan, K.J. (1991). A review of the Hoki fishery and Young, J.W. and S.J.M. Blaber ( l 986). The feedingecology research on Hoki stocks in New Zealand. In Abel, K., of three species of midwater fish associated with the M. Williams and P. Smith (Eds.)(1991). "Australian continental slope off Tasmania. Marine Biology 98, and New Zealand Southern Trawl Fisheries Confer­ 147-156. ence: Issues and Opportunities", Bureau of Rural Resources, Proceedings No.JO, Pirie Printers Sales, Young, J.W. and T.L.O. Davis (in press). Feeding ecology Canberra, 266pp. oflarvae of jack mackerel, Trachurus dec!ivis (Pisces: Carangidae), from coastal waters of EasternTasmania. Thorson, G. (1971). "Life in the Sea," Weidenfeld and Marine Biology. Nicolson, London, 256pp.

Veron, J.E.N. (1986). "Corals of Australia and the Indo­ Pacific," Angus and Robertson, Hong Kong, 644pp. Weinstein, M.P. and K.L. Heck Jnr (1979). Ichthyofauna of seagrass meadows along the Caribbean coast of Panama and in the Gulf of Mexico: composition, structure and community ecology. Marine Biology 50, 97-107. Werner, E.E., G.G. Mittelbach, D.J. Hall and J.F. Gilliam (1983). Experimental tests of optimal habitat use in fish: the role of relative habitat profitability. Ecology 64(6), 1525-39.

West, R. (1989). How are seagrass meadows destroyed and when should attempts be made to restore them? In G. Edgar and H. Kirkman (eds.)(1989). "Recovery and Restoration of Seagrass Habitat of Significance to Commercial Fisheries," Victorian Institllfe of Marine Sciences, Working Paper (I9), 37pp.

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Wood, E.J.F. and R.E. Johannes (Eds.)(1975). "Tropical Marine Pollution," Elsevier, Amsterdam, pp. 64-74. Young, P.C. and H. Kirkman (l 975). The seagrass commu­ nities of Moreton Bay, Queensland. Aquatic Botany 1, 191-202. Young, P.C. and V. Wadley (1979). Distribution of Shal­ low-Water Epibenthic Macrofauna in Moreton Bay, Queensland, Australia. Marine Biology 53, 83-97. Young, P.C., J.M. Leis and H. Hausfeld (1986). Seasonal and spatial distribution of fish larvae in waters over the North West Continental Shelf of Western Aus­ tralia. Marine Ecological Progress Series 31, 209-22.

94 Bureau of Resource Sciences Proceedings DEFINING KEY FACTORS RELATING FISH POPULATIONS IN ESTUARIES AND THEIR HABITATS

N.R. Loneragan CS/RO Division of Fisheries, Cleveland Marine Laboratories PO Box 120 Cleveland OLD 4163

Summary Introduction Some of the recent literature is reviewed and Estuaries are complex ecosystems in which results of detailed studies of fish and crustacean environmental conditions are influenced by populations in temperate estuaries of south­ water derived from both riverine and marine western Australia and New South Wales are sources. Furthe1more, a wide variety of species synthesised and the approaches to these studies of fish, representing different life cycle discussed. Studies on the west coast of Aus­ categories, is found in estuaries (Loneragan et tralia have concentrated on defining seasonal, al. 1989; Potter et al. 1990). The influence of annual and spatial patterns of change in the fish environmental factors can vary greatly among fauna of the Swan and Peel-Harvey estuaries. the different life cycle categories of fish. For The emphasis has been on obtaining detailed example, marine species are generally influenced knowledge of the life history strategies of fish to a greater extent by changes in salinity than in estuaries and interpreting the main factors estuarine or anadromous species. affecting the fish populations and community In this paper, I outline some of the structure in light of this information. On the east environmental variation found in estuaries, coast, more effort has been directed towards discuss the fish fauna found with estuarine evaluating the importance of various habitats to systems and examine approaches to the study of fish in estuaries, particularly seagrass habitats key factors which influencethe fish fauna. Most in several different estuarine and inshore coastal of the discussion will focus on temperate systems. Conventional sampling techniques (i.e. estuarine systems in Australia, particularly those beach seines, gill nets, otter and beam trawls) in south-western and south-eastern Australia. have been used to study fish populations in In reviewing studies of estuarine fish estuaries of both regions. In addition, in West­ populations, it is important to consider details of em Australia, commercial catch data in the the spatial and temporal scales that were used, Peel-Harvey and Swan estuaries have been as these can greatly influence the results and used to assess how fish populations have re­ interpretation of the important factors sponded to the marked eutrophication in the influencing the fish populations. former system. Artificial seagrass has also been used in NSW to test hypotheses about the im­ portance of seagrass to larval and juvenile fish.

Bureau of Resource Sciences Proceedings 95 The estuarine environment (Day 1981; McComb et al. 1981). In tropical regions of Australia, viitually all the rainfall is Pritchard (1967) proposed the first widely ac­ in summer and early autumn, and the total cepted definition of an estuary, namely that an annual rainfall can be at least twice that of the estuary is a semi-enclosed body of water which above temperate regions (e.g. Davis 1988). The has a free connection with the open sea and pattern of rainfall influences the timing of within which sea water is measurably diluted changes in hydrological conditions within es­ with fresh water derived from land drainage. tuarine systems and hence the times when these However, this definition does not cover the environments are suitable for colonisation by types of environment found in many estuaries in marine flora and fauna. southernAfrica and parts of Australia (particu­ larly the south-west) where sand bars may form The influence of marine waters on the hy­ at the mouths of estuaries and the water within drology of an estuary can also vary greatly the estuary can become markedly hypersaline. between systems. Thus, in funnel shaped estuar­ In order to include these systems, Day (1980; ies, i.e. estuaries with a broad mouth and a 1981) proposed that an estuary is a partially channel width which decreases progressively enclosed coastal body of water which is either with distance upstream, the influence of tides permanently or periodically open to the sea and can be greatly accentuated (Day 1981). Con­ within which there is a measurable variation of trasting with this pattern of tidal accentuation, is salinity due to the mixture of sea water with the situation in many estuaries, particularly those fresh water derived from land drainage. in southern Australia, where the tidal energy and the resulting change in water level, dimin­ Since estuaries are regions where there is a ishes with distance fromthe estuary mouth (Day mixing of water derived from both oceanic and 1981). riverine sources, they are typically environ­ ments where characteristics of the water column can undergo pronounced fluctuations (Day et al. 1981; Haedrich 1983). In addition to a salin­ The fish fauna of estuaries ity gradient along the estuary, there may be Relatively large numbers of the juveniles of abrupt and large changes in salinity, tempera­ some marine teleosts regularly enter estuaries in ture, dissolved oxygen, turbidity, flow and nu­ the temperate regions of both the Northern and trient levels (Haedrich 1983; Cloern and Nichols Southernhemispheres (e.g. Gunter 1938; Pearcy 1985). The amount of fresh water flowing into and Richards 1962; McHugh 1967; Cronin and estuarine systems varies greatly according to Mansueti 1971; Day etal. 1981; Haedrich 1983; latitude, the seasonal pattern and quantity of Claridge et al. 1986). It is for this reason that rainfall, and characteristics of the catchment estuaries have often been referred to as fish ( e.g. amount of clearing, soil type and gradient nursery areas (Cronin and Mansueti 1971; of slope into the tributary rivers) (Day 1981 ). An Haedrich 1983; Blaber 1985; Potter etal. 1990). example of the variation in patterns of annual Many other marine species are found only in rainfall is provided below. In the temperate small numbers in estuaries and generally in the lowlands of Europe, the annual rainfall is ap­ high salinity regions towards their mouths proximately 650-760 mm and it rains through­ (Haedrich 1983; Claridge et al. 1986). out the year. Relatively continuous rainfall also occurs in Melbourne, south-eastern Australia Estuaries are used by anadromous species and Christchurch, New Zealand (Day 1981 ). By as a route between feeding areas in marine contrast, both Cape Town in South Africa and waters and their spawning grounds in freshwa­ Perth in south-western Australia have a similar ter, whereas they allow the reverse migration in total annual rainfall, but most rain falls in winter the case of catadromous species (Day et al.

96 Bureau of Resource Sciences Proceedings 1981; Haedrich 1983; Dando 1984). A few easternAustralia (Pollard 197 6;1981). Although species of teleost, almost certainly of marine this value for estuarine-dependent species is origin, have evolved the ability to complete the lower for south-westernAustralia and forAus­ whole of their lifecycle within estuarine envi­ tralia as a whole (20 and 32%, respectively), this ronments (Ross and Epperley 1985;Potter etal. still represents a large catch (Newell and Barber 1986a;1990). Some of these 'estuarine' species 1975; Lenanton and Potter 1987). In addition to are also represented by populations in marine commercial fishing, recreational fishing is an environments (Lenanton 1977; Prince et al. important activity in estuaries in many regions 1982; Chrystal etal. 1985; Potter etal. 1986b). of the world (Caputi 1976; Lenanton 1979; Day The upper reaches of estuaries are occasionally et al. 1981; Marais 1988). penetrated by a few of the more euryhaline freshwaterteleosts (Cronin and Mansueti 1971; Day etal. 1981). Factors influencing fish in estuaries The very high numbers of the juveniles of Several hypotheses have been invoked to ex­ some of the marine species of teleost foundin plain why estuaries are used so extensively by estuaries have led to these species frequently the juveniles of marine fishes. For example, it being included with estuarine and diadromous has been suggested that, because estuaries are species in a category termed estuarine-depend­ among the most productive environments in the ent (Clarke etal. 1969;Pollard 1976; 1981; Van world (Whittaker 1975; Correll 1978; Mann den Broek 1979; Fourtier and Legget 1982; 1982), they supply an abundance of food,thereby Haedrich 1983; Beckley 1984; Blaber 1987). facilitating the growth of juvenile fish. Further­ Since several recent studies have shown that a more, the presence of higher temperatures in numberof these marine species which are found estuaries than in marine waters would facilitate in abundance in estuaries also utilize marine increased growth rates of fish in estuarine envi­ environments extensively at the same stage of ronments. In addition to the higher growth rates their lifecycles (Lenanton 1982;Beckley 1984; in estuaries, predation rates are believed to be Smale 1984; Lenanton and Potter 1987), it has lower in estuaries than the ocean. This view is been suggested that these species would be supported by the fact that the incidence of large more appropriately termed 'estuarine-oppor­ teleost piscivores is generally lower in estuaries tunists' (Hedgpeth 1982; Lenanton and Potter than in marine waters (Blaber 1980; Blaber and 1987). A number of the marine teleosts which Blaber 1980; Haedrich 1983). The macrophyte utilize estuaries as nurseries contribute to im­ beds and turbid waters which are often found in portant commercial and recreational fisheries in estuaries are likely to increase protection from either or both marine and estuarine waters. There predation in these systems (Blaber and Blaber is thus a clear need to preserve estuarine envi­ 1980; Lenanton et al. 1984; Cyrus and Blaber ronments for the successful management of a 1987a; b). number of important fisheries (e.g. McHugh 1976; Beal 1980). The importance of estuaries The number of species, density of indi­ to commercial fisheries is emphasised by the vidual species and the species composition of fact that the 'estuarine-dependent' species of the fish community undergo seasonal changes fish and crustaceans comprised 69% of the total in many estuaries (Gunter 1938; Dahlberg and weight landed by the commercial fishery of the Odum 1970; McErlean et al. 1973; Haedrich United States in 1970 (McHugh 1967). Estua­ and Haedrich 1974; Livingston 1976; Quinn rine-dependent species have been estimated as 1980; Bell et al. 1984; Claridge et al. 1986; contributing a similarly high proportion (70%) Quinn and Kojis 1986). While these cycles have to the commercial fisheriesin New South Wales, often been related to salinity and/or tempera-

Bureau of Resource Sciences Proceedings 97 ture, other variables, particularly in tropical or In a review of estuarine fish studies, sub-tropical estuaries, may be more important Haedrich ( 1983) made a plea forfurther work on in some cases. For example, in Moreton Bay in the life history of fishes within estuaries, as well eastern Australia and the Lake St. Lucia estua­ as highlighting the paucity of long term studies rine system of South Africa, turbidity was im­ in these environments. Few studies of estuarine portant when spatial differences in salinity were fish appear to have exceeded two years in dura­ relatively small (Blaber and Blaber 1980; Cyrus tion (Haedrich 1983) and of those which have and Blaber 1987a; b).Similarly, in the absence spanned a longer time period, most appear to of a strong salinity gradient, distance from estu­ have sampled only a limited number of sites or ary mouth had an important influence on the range of estuarine conditions. Thus, in a five abundance and composition of juvenile fish year study of the fish fauna in a lagoon on the associated with seagrass (Zostera capricorni)in west coast of the United States, beach seines the Hawkesbury River Estuary, eastern Aus­ were used to catch fish at four sites, all with tralia (Bell et al. 1988). From the above, it can salinities very close to that of sea water, sepa­ be seen that abiotic factors such as salinity, rated by distances of less than 2 km (Onuf and temperature, distance from estuary mouth and Quammen 1983). The six year investigation of turbidity, and biotic variables such as aquatic Hillmanetal. ( 1977) was also carried out at sites vegetation, predation and competition, may af­ with salinities very similar to that of the ocean. fect the distribution and abundance of indi­ Although significant seasonal variations in sa­ vidual species and the structure of the fish linity were recorded during a five year study of communities of estuaries (see also Orth and the fish fauna in the Severn Estuary, United Heck 1980; Young 1981; Orth et al. 1984; Kingdom, the. major data source came from Pollard 1984). sampling at only one site (Claridge et al. 1986; Potter et al. 1986a). Very little is thus known of the relative imp011ance of the influence of site within estuary, season and year on the abun­ Estuarine fish studies dance, and community structure of fish Both the sampling methods used to investigate populations in estuaries. the fish fauna in estuaries and the range of estuarine environments sampled, have varied greatly among studies. For example, Thorman Approaches to studies of fish ( 1986) utilized a small beach seine to sample populations in Western Australian fish at sites along 60 km of the southern Bothnian estuaries Sea, whereas Little et al. ( 1988) used the same method of sampling at four sites in a tropical Work in the Swan Estuary of south-western mangrove creek with no more than 5 km Australia was undertaken over a five year period separating the most distant sites. In the former to gain a detailed understanding of the tax­ study, salinities were always less than 10%0, onomy and life histories of the fish found in this whereas they were very close to that of sea water estuary; to investigate changes in the abundance in the mangrove creek (34-36%0).Differences in of species and the composition of the fish fauna the scale of an investigation, such as those over the length of the system and with season outlined above, can dramatically influence the and year; and to understand how different spe­ results and hence the conclusions drawn from a cies were affected by changes in environmental study (Doherty and Williams 1988; Levin 1992). variables, particularly salinity and temperature. This point is often overlooked when comparisons These studies were joint! y directed by Ian Potter are made between the findings from different of Murdoch University and Rod Lenanton of the studies. Bernard Bowen Fisheries Research Institute,

98 Bureau of Resource Sciences Proceedings with funding fromthe WesternAustralian De­ The most abundant families of fish in the partments of Fisheries, and Conservation and Swan were the Clupeidae, Terapontidae, Environment. Mugilidae, Apogonidae and Atherinidae. Of the 15 most abundant species in the shallows of The Swan Estuary covers a surface area of the Swan Estuary, seven were marine teleosts approximately 53 km2 and is the second largest which entered the estuary regularly and in large estuarine system in south-western Australia. numbers(marine estuarine-opportunists), seven This estuary and that of the Peel-Harvey (c 80 completed their life cycle within the estuary km south) are two pe1manently open systems on (estuarine) and one (Nematalosa vlaminghi ) the west coast, whose mouths are separated by was anadromous. The contribution of individu­ a distance of about 55 km. They are the most als of the marine estuarine-opportunist category important estuaries for commercial and recrea­ to catches in the shallows declined from nearly tional fishing in this region (Lenanton 1979; 95% in the lower estuary, to approximately Lenanton 1984; Lenanton et al. 1984). 17% in the middle estuary and 6% in the upper The Swan Estuary comprises a long, nar­ estuary. The estuarine and anadromous groups row Entrance Channel that opens into extensive together cornprised 83 and 94 % of the catches in wide basins, which in turn lead into tidal, saline the middle and upper estuaries, respectively. riverine areas, termed the lower, middle and upper estuary, respectively. Over the five year The number of species and density of fish study, mean salinity ranged from 30%oto 8.6%0 (measures of community structure) were influ­ in the lower and upper estuary respectively enced by distance from the estuary mouth, sa­ (Loneragan et al. 1989). By contrast, mean linity and temperature; they declined with temperature during this period was relatively distance from estuary mouth and rose with constant ( c 20°C) throughout the estuary. Vari­ increasing salinity and temperature. Classifica­ ation in salinity increased with distance fromthe tion and ordination distinguished the estuary mouth, whereas the variation in tem­ ichthyofauna of the saline reaches of the rivers perature was relatively stable in the different from that of the lower reaches of the estuary. regions of the estuary. Both salinity and tem­ The fauna!composition of the middle estuary of perature were lower in the winter and spring the Swan was also relatively distinct from those than the summer and autumn. In the upper of the lower and upper estuary (Loneragan and estuary, salinities can increase to about 30%0 Potter 1990). A secondary pattern of variation during the late summer and early autumn, only in the fish fauna, due to seasonal changes in slightly lower than salinities in the middle and composition, particularly in the upper estuary, lower estuary at this time. Other environmental was also detected using classification and variables such as turbidity, freshwater flow and ordination. nutrient levels are likely to vary in a similar way Site within the Swan Estuary generally to the variation with distance from estuary mouth influenced the densities of individual species to and season shown by salinity. a greater extent than either Season or Year, or Large beach seines (swept area= 1 670 m2 the interactions between these factors. When 2 and 2 815 m ) were used over a five year period seasonal effects were important, they could be to sample fish at ten sites in the shallow waters related to summer spawning migrations into the of the Swan Estuary (see Loneragan etal. 1989). upper estuary (Nematalosa vlaminghi, Sampling for most of this study was at fort­ Amniataba caudavittatus), spring recruitment nightly or monthly intervals. In terms of dis­ ofO+ individuals into the lower estuary (Mugil tance from the estuary mouth, the sites were cephalus) or winter movements into deeper and from2 to 44 km upstream of the mouth. more salinewaters(Apogon rneppellii).Marked

Bureau of Resource Sciences Proceedings 99 annual variations in the density of Torquigener The results of much of the work on the pieuro gramma were related to large differences importance of seagrass systems to fish in the recruitment of the O+ age class between populations in Australia have been summarised years. by Bell and Pollard (1989). In their introduction they summarise the findingsof previous stud­ The studies within the Swan have helped to ies and reviews with the following (modified gain an understanding of the life histories and from Bell and Pollard 1989): factors affecting fish populations over a broad spatial scale. More recent work has focussed on the diversity and density offish are usually a finer spatial scale and has investigated the higher in seagrass than nearby bare areas; importance of macrophytes to fish in Wilson fish and decapods are found in seagrass for Inlet, a seasonally closed estuary on the south different lengths of time and at different coast of Western Australia (Humphries et al. stages of the life history; 1992). many fish species settle into seagrass from the plankton; Approaches to studies of fish seagrass, seagrass detritus and infauna of populations in New South Wales the seagrass are an underutilised food estuaries source for most species of fish compared to planktonic and epifaunal crustaceans; Much of the work in New South Wales has been carried out under the direction of Johann Bell different species of fish are found in and Dave Pollard of the NSW Fisheries Re­ different pbsitions in the seagrass canopy; search Institute. Detailed studies of fish the composition of the fish community and populations in estuaries have been completed in the relative abundance of different species Botany Bay (e.g. Anon. 1981a; b) and in more can be influenced by the position of the bed recent years, concurrently in several estuaries in relation to other habitats and on the time along the coast of NSW (e.g. Ferrell and Bell of day; and 1991; McNeill et al. 1992; Worthington et al. 1992). Both these major studies were initiated in the species composition of different response to potential environmental impacts in seagrass beds often differs,even when the coastal regions: extensions to Sydney airport in beds are adjacent. Botany Bay; and proposed development of port The imp01tance of different habitats to fish facilities in Jervis Bay forthe Navy. populations has been investigated by field In general, the focus in these studies has sampling in single estuarine systems and more been on establishing the importance of various recently through concurrent sampling of a habitats to fish and decapod populations, par­ number of estuaries over the 18 months. The ticularly seagrass compared with bare substrate. abundances of differentspecies has then been These studies have been carried out in regions of correlated with attributes of the habitat, such as estuarine systems which appear to have a simi­ the shoot density of seagrass (e.g. Worthington lar variation in salinity to that found in the lower et al. 1992). The results of these studies have Swan Estuary. The fish fauna is thus likely to be been enhanced through the use of experimental dominated by the juvenile stages of marine field studies to test hypotheses about the species. Estuarine and migratory (i.e. importance of seagrass to fishes. This has anadromous and catadromous) species are not involved studying settlement of larvae in likely to have been major contributors to the fish artificial seagrass and examining the effect of fauna in these studies. manipulating the height and density of naturally

100 Bureau of Resource Sciences Proceedings occuring seagrass on the associated fauna (Bell Because of the detailed knowledge of fish et al. 1985; 1987; 1988; Bell and Westoby populations in open estuaries and inshore waters 1986). of the west coast, it is timely to consider testing the generally held hypotheses about estuaries From the general increase in abundance of concerning their high productivity and refuge fish and crustaceans with increased seagrass value for fish. Since the variation in the fish structure (i.e. higher shoot density, biomass) fauna is now well documented over a relatively within a seagrass bed, it was proposed that large spatial scale, it is also appropriate to exam­ predation and habitat selection were the main ine the importance of differenthabitat types in processes explaining these correlations (Heck regions where environmental conditions are simi­ and Orth 1980; Orth et al. 1984). More recently lar e.g. importance of seagrass in the lower and Bell and Westoby (1986) proposed an alterna­ middle Swan system. Further work also needs to tive hypothesis: that the distribution of fish and be undertaken to determine whether the factors crustaceans among separate seagrass beds re­ affecting fish populations in open estuaries are flects the supply of larvae to those beds. They the same in seasonally open and closed systems. proposed that larvae settle to the firstbed they encounter, regardless of the characteristics of In the studies of fish populations of estuar­ the seagrass, and that individuals rarely leave ies of New South Wales, most of the studies the shelter of that bed during the following three appear to have been undertaken at a smaller to four months. Both the experimental field spatial scale within a particular system. At this studies and the more descriptive work support level, variation in habitat type has an important the supply hypothesis. Worthington etal. (1992) influence on fish populations and community conclude that the density of seagrass shoots structure. Levin (1992) has suggested that the explained little of the large scale variation in mechanisms affecting populations and commu­ abundance of fish and decapods among sepa­ nities vary according to the scale of the study and rate seagrass beds and that their data support the the hypotheses being investigated. This general­ supply model. ity certainly seems to apply to studies of fish populations in estuaries on the east and west coasts of Australia. If we are interested in fish of the lower region of the estuary where salinity is Summary and future directions relatively stable, then different habitat types and location of the habitats may determine the com­ Work on the fish faunas found in estuaries is position of the fish community and abundance challenging due to the variability in both the of different species. However, if the hypothesis types of species of fish found in these systems concerns the system as a whole, then distance and in the environment itself. The approach of from the estuary mouth and associated variables studying lifehistories has greatly improved our such as salinity are the key variables. understanding of the dynamics of fish populations in estuaries of south-western Aus­ Bell and Pollard ( 1989) have discussed ar­ tralia and the environmental factors which af­ eas for new work on fish fauna in seagrass fect populations and the composition of the systems and suggested that the following areas fauna. Over the relatively large spatial scales were important: investigated in these studies, distance from • the effect of size, shape and location of the estuary mouth and salinity (hence also the hy­ habitat within the estuary; drology and characteristics of the catchment) have been identified as key factors affectingthe the hypothesis that fish and decapods settle composition of the fish fauna in the Swan in the first bed they encounter and do not Estuary. leave the bed; and

Bureau of Resource Sciences Proceedings 101 differences in fish communities between Bell, J.D., AS. Steffe and M. Westaby (1985). Artificial different seagrass beds within the same seagrass: how useful is it for field experiments on fish and macroinvertebrates. Journal of Experimental estuary-are they due do the fact that the Marine Biology and Ecology 90, 171-177. beds may be situated at different depths or to differences in the attributes of the Bell, J.D., AS. Steffe and M. Westaby (1988). Location of seagrass beds in estuaries: effects on associated fish seagrass? Does seagrass possess important and decapods. Journal of E.\perime11talMarine Biol­ attributes forfish popoulations or will dif­ ogy and Ecology 122, 127-146. ferent structures generate the same pat­ Bell, J.D., M. Westaby and A. S. Steffe (1987). Fish larvae terns in abundance? settling in seagrass: do they discriminate between beds of different leaf density? Journal of Experimental In addition to these hypotheses, recent work Marine Biology and Ecology 111, 133-144. by Underwood (1993) has challenged us to Bell, J.D., D. A. Pollard, J. J. Burchmore, B.C. Pease and consider the design of studies on fishpopulations M.J. Middleton (l984). Structure of a fish community where the aim is to detect the effects of an in a temperate tidal mangrove creek in Botany Bay, impact. Can we apply his concept of multiple New South Wales. Australian Journal of Marine and control estuaries when the catchment character­ Freshwater Research 35, 33-46. istics and morphology (hence hydrology and Blaber, S.J.M. (1980). Fish of the Trinity Inlet system of salinity regimes) of different systems vary north Queensland with notes on the ecology of fish greatly? faunas of tropical Inda-Pacific estuaries. Australian Journalof Marine and Freshwater Research 31, 137- 146. Blaber, S.J.M. (1985). The ecology of fishes of estuaries and lagoons of the Inda-Pacific with particular referenceto References southeast Africa. In: Fish comm1111ity ecology in estu­ aries and coastal lagoons: towards an ecosystem Anon. (1981a). The ecology of fish in Botany Bay­ integration. pp 247-266. Yanez-Arancibia, A. (Ed.). community structure. State Pollution Control Universidad Nacional Automoma de Mexico. ISBN Commissio110JNewS0111h Wales. Report No. BBS23A. 968-837-618-3. Anon. (l 981b). The ecology of fish in Botany Bay­ Blaber, S.J.M. (l987). Factors affecting recruitment and biology of commercially and recreationally important survival of mugilids in estuaries and coastal waters of species. State Pollution Control Commission (!{New southeastern Africa. Transactions of the American South Wales. Report No. BBS23B. Fisheries Society Symposium 1, 507-518. Beal, K.L. (1980). Territorial sea fisheries management and Blaber, S.J.M. and T.G. Blaber (1980). Factors affecting the estuarine dependence. In: Estuarine perspectives. distribution of juvenile estuarine and inshore fish. pp67-77. Kennedy, V.S. (Ed.) Academic Press, Journalo{Fish Biology 17, 143-162. London. Caputi, N. (1976). Creel census of amateur line fishermen in Beckley, L.E. (1984). The ichthyofauna of the Sundays the Blackwood River Estuary, Western Australia. Estuary, South Africa, with particular referenceto the Australian Journal of Marine and Freshwater Re­ juvenile marine component. Estuaries 7, 248-258. search 27, 583-593.

Bell, J .D. and D.A. Pollard ( l 989). Ecology of fish Chrystal, P.J., !.C. Potter N. R. Loneragan and C.P. Holt assemblages and fisheries associated with seagrasses. (1985). Age structure, growth rates, movement pat­ In Larkun1, A.D. W., A.J. McComb and S. Shepherd terns and feeding in an estuarine population of the (Eds) A. Biology of seagrasses: A treatise 011 the cardinalfish Apogo11 rueppel/ii. Marine Biology 85, biology of seagrasses with special reference to the 185-197. Australian region, pp565-609. Claridge, P.N., !.C. Potter and M.W. Hardisty (1986). Sea­ Bell, J.D. and M. Westaby (1986). Importance of local sonal changes in movements, abundance, size compo­ changes in leaf height and density to fish and decapods sition and diversity ·of the fish fauna of the Severn associated with seagrasses. Journal of Experimelllal Estuary. Jouma/ of the Marine Biological Association Marine Biology and Ecology 104, 249-274. of the United Kingdom 66, 229-258.

102 Bureau of Resource Sciences Proceedings Clarke, J., W.G. Smith, W. Kendall. and M.P. Fahay Ferrell, DJ. and J.D. Bell. (1991). Differences among as­ (1969). Studies of estuarine dependence of Atlantic semblages of fish associated with Zostera capricorni coastal fishes. United States Fisheries and Wildlife and bare sand over a large spatial scale. Marine Ecol­ Services Technical Paper No. 28. ogy Progress Series 72, 15-24. Cioem, J.E. and F.H. Nichols (1985). Time scales and Fourtier, L. and W.C. Leggett (1982). Fickian transport and mechanisms of estuarine variability, a synthesis from the dispersal of fish larvae in estuaries. Canadian studies of San Francisco Bay. Hydrobiologia 129, Joumal of Fisheries and Aquatic Sciences 39, 1150- 229-237. 1163.

Correll, D.L. (1978). Estuarine productivity. BioSciences Gunter, G. (1938). Seasonal variations in abundance of 28, 646-650. certain estuarine and marine fishes in Louisiana, with particular referenceto life histories. Ecological mono­ Cronin, L.E. and A. J. Mansueti (1971). The biology of the graphs 8, 314-346. estuary. In: A symposium on the biological signifi­ cance of estuaries, 14-39. Douglas, P.A. and Stroud, Haedrich, R.L. (1983). Estuarine fishes. In: Ecosystems of R.H. (Eds). Sport Fishing Institute, Washington, D.C. the world26: Estuaries and enclosed seas. pp 183-207. Ketchum, B.H. (Ed.). Elsevier Scientific Publishing Cyrus, D.P. and S.J.M. Blaber (1987a). The influence of Company, Oxford. turbidity on juvenile fishes in estuaries. Part I. Field studies at Lake St. Lucia on the southeastern coast of Haedrich, R.L. and S.O. Haedrich (1974). A seasonal survey South Africa.Journal of Experimental Marine Biol­ of the fishes in the Mystic River, a polluted estuary in ogy and Ecology 109, 53-70. downtown Boston, Massachusetts. Estuarine, Coastal and Marine Science 2, 59-73. Cyrus, D.P. and S.J.M. Blaber (1987b). The influence of turbidity on juvenile fishes in estuaries. Part 2. Labo­ Heck, K.L. Jr. and R.J. Orth (1980). Seagrass habitats: the ratory studies, comparisons with field data and con­ roles of habitat complexity, competition and predation clusions. Journal of Experimental Marine Biology in structuring associated fish and motile and Ecology 109, 71-91. macroinvertebrate assemblages. In: Estuarine Per­ spectives. Kennedy, V. S. (Ed). pp 449-464. Academic Dahlberg, M.D. and E.P. Odum (1970). Annual cycles of Press, New York. species occurrence, abundance, and diversity in Geor­ gia estuarine fish populations. American Midland Hedgpeth, J.W. (1982). Estuarine dependence and Naturalist 83, 382-392. colonisation. Atlantica 5, 57-58.

Dando, P.R. (1984). Reproduction in estuarine fish. In: Hillman, R.E., N. W. Davis and J. Wennemer (1977). Abun­ Fish reproduction strategies and tactics. pp 155-170. dance, diversity and stability in shore-zone fish com­ Potts, G. W. and R. J. Wootton (Eds.). Academic munities in an area of Long Island Sound affected by Press, London. the thermal discharge of a nuclear power station. Estuarine, Coastal and Marine Science 5, 355-381. Davis, T.L.O. (1988). Temporal changes in the fish fauna entering a tidal swamp system in tropical Australia. Humphries, P., J.C. Potter and N.R. Loneragan (1992). The Environmental Biology of Fishes 21, 161-172. fish community in the shallows of a temperate Austral­ ian estuary: relationships with the aquatic macrophyte Day, J .H. ( 1980). What is an estuary? South African Joumal Ruppia megacmpa and environmental variables. Es­ of Science 76, 198. tuarine, Coastal and Shelf Science 34, 325-346. Day, J.H. (1981). Estuarine currents, salinities and tem­ Lenanton, R.C.J. (1977). Fishes from the hypersaline waters peratures. In: Estuarine ecology with particular ref­ of the stromatolite zone of Shark Bay, Western Aus­ erence to Southem Africa. pp 27-44. Day, J.H. (Ed.). tralia. Copeia 1977, 387-390. Balkema, Rotterdam. Lenanton, R.C.J. (1979). The inshore-marine and estuarine Day, J.H., S.J. M Blaber and J. H. Wallace (1981). Estua­ licensed amateur fishery of WesternAustralia. Fisher­ rine fishes. In: Estuarine ecology with particular ies Research Bulletin of Western Australia 23, 1-33. reference to SouthernAf rica. pp 197-221. Day, J.H. (Ed.). Balkema, Rotterdam. Lenanton, R.C.J. (1982). Alternative non-estuarine nursery habitats for some commercially and recreationally Doherty, P.J. and D. McB Williams (1988). The replenish­ important fish species of south-western Australia. ment of coral reef fish populations. Oceanography Australian Joumal of Marine and Freshwater Sciences and Marine Biology Annual Reviews 26, 487-551. 33, 881-890.

Bureau of Resource Sciences Proceedings 103 Lenanton, R.C.J. (1984). The commercial fisheries of tem­ McNeill, S.E., D.G. Worthington, D. J. Ferrell and J. D. Bell perate Western Australian estuaries: early settlement (1992). Consistently outstanding recruitment of five to 1975. Report of the Department of Fisheries and species of fish to a seagrass bed in Botany Bay, NSW. Wildlife of Western Australia 62, 1-82. Australian Journal of Ecology, 17, 359-365. Lenanton, R.C.J. and I.C. Potter (1987). Contribution of Newell, B.S. and W.E. Barber (1975). Estuaries important to estuaries to commercial fisheries in temperate West­ Australian fisheries. Australian Fisheries 34, 17-22. ern Australia and the concept of estuarine depend­ ence. Estuaries 10, 28-35. Onuf, C.P. and M.L. Quammen (1983). Fishes in a Califor­ nia coastal lagoon: effects of major storms on distribu­ Lenanton, R.C.J., I.C. Potter, N. R. Loneragan and P.J. tion and abundance. Marine Ecology Progress Series Chrystal (1984). Age structure and changes in abun­ 12, 1-14. dance of three important teleosts in a eutrophic estu­ Orth, R.J. and K.L. Heck Jr. (1980). Structural components ary. Journal of Zoology, London 203, 311-327. of eelgrass, (Zostera marina) meadows in the lower Levin, S.A. (1992). The problem of pattern and scale in Chesapeake Bay. Fishes. Estuaries 3, 278-288. ecology. Ecology 73, 1943-1967. Orth, R.J., K.L. Heck Jr. andJ. van Montfrans(1984). Fauna! Little, M.C., P.J. Reay and S.J. Grove. (1988). The fish communities in seagrass beds: a review of the influ­ community of an east Africanmangrove creek. Jour­ ence of plant structure and prey characteristics on nal of Fish Biology 32, 729-747. predator-prey relationships. Estuaries 7, 339-350.

Livingston, R.J. (1976). Diurnal and seasonal fluctuations Pearcy, W.G. and S.W. Richards (1962). Distribution and of organisms in a North Florida estuary. Estuarine, ecology of fishes of the Mystic River Estuary, Con­ Coastal and Marine Science 4, 373-400. necticut. Ecology 43, 248-259.

Loneragan, N.R. and I.C. Potter ( 1990). Factors influencing Pollard, D.A. (I 976). Estuaries must be protected. Austral­ fish community structure and distribution of different ian Fisheries 36, 6-10. life-cycle categories in shallow waters of a large Australian estuary. Marine Biology 106, 25-38. Pollard, D.A. (I 981). Estuaries are valuable contributors to fish production. Australian Fisheries 40, 7-9. Loneragan, N.R., J.C. Potter and R. C. J. Lenanton (1989). Influence of site, season and year on contributions Pollard, D.A. (1984). A review of ecological studies on made by marine, estuarine, diadromous and freshwa­ seagrass-fish communities with particular reference to ter species to the fish fauna of a temperate Australian recent studies in Australia. Aquatic Botany 18, 3-42. estuary. Marine Biology 103, 461-479. Potter, J.C., P.N. Claridge and R.M. Warwick (1986a). Consistency of seasonal changes in an estuarine fish Mann, K.H. (I 982). Ecology of coastal waters. University of California Press, Los Angeles, 322pp. assemblage. Marine Ecology Progress Series 32, 217-228. Marais, J.F.K. (1988). Some factors that influence fish Potter, J.C., W. Ivantsoff, R. Cameron and J. Minnard abundance in South African estuaries. Solllh African (1986b). Life cycles and distribution of atherinids in Journal of Science 6, 67-77. the marine and estuarine waters of southernAustralia. McComb, A.J., R.P. Atkins, P.B. Birch, D.G. Gordon and Hydrobiologia 139, 23-40. R.J. Lukatelich (1981). Eutrophication in the Peel­ Potter, J.C.,L.E. Beckley, A.K. Whitfield and R.C.J. Lenanton Harvey estuarine system. In: Nlllrient enrichment in estuaries, pp 323-342. Nielson, B.J. and L.F Cronin (1990). Comparisons between the roles played by (Eds). Humana Press, New Jersey. estuaries in the life cycles of fishes in temperate West­ ern Australia and southern Africa. Environmental Bi­ McErlean, A.J., S.G. O'Connor, J.A. Mihursky and C.J. ology of Fishes 28, 143-178. Gibson ( 1973). Abundance, diversity and seasonal patternsof esturine fish populations. Estuarine, Coastal Prince,J.D.,J.C. Potter,R.C.J. Len an ton and N.R. Loneragan and Marine Science l, 19-36 ( 1982). Segregation and feeding of atherinid species (Teleostei) in south-westernAustralian estuaries. Aus­ McHugh, J.L. (1967). Estuarine nekton. In: Estuaries. tralian Journal of Marine and Freshwater Research pp 581-620. Lauff, G.H. (Ed.). American Association 33, 865-880. forthe Advancement of Science, Washington D.C. Pritchard, D. W. (1967). What is an estuary, physical McHugh, J.L. (1976). Estuarine fisheries: are they doomed? viewpoint. In: Estuaries. pp 3-5. Lauff, G. (Ed.) In: Estuarine processes l, 15-27. Wiley, M. (Ed.). American Association for the Advancement of Science, Academic Press, New York. Washington, D.C.

104 Bureau of Resource Sciences Proceedings Quinn, R.J. (1980). Analysis of temporal changes in fish assemblages in Serpentine Creek, Queensland. Envi­ ronmelllal Biology of Fishes 5, 117-133.

Quinn, R.J. and B.L. Kojis (1986). Annual variation in the nocturnal nekton assemblage of a tropical estuary. Estuarine, Coastal and Shelf Science 22, 63-90. Ross, S.W. and S.P. Epperly (1985). Utilization of shallow estuarine nursery areas by fishes in Pamlico Sound and adjacent tributaries, North Carolina. In: Fish community ecology in estuaries and coastal lagoons: towards an ecosystem integration. pp 207-232. Yanez-Arancibia, A. (Ed.) Universidad Nacional Automoma de Mexico. ISBN 968-837-618-3. Smale, M.J. (1984). Inshore small-mesh trawling survey of the Cape south coast. Part 3. The occurrence and feeding of Argyrosomus hololepidotus, Pomatomus sa/tatrix and Merluccius capensis. South African J our­ nal of Zoology 19, 170-179.

Thorman, S. (1986). Physical factors affecting the abun­ dance and species richness of fishes in the shallow waters of the southernBothnian Sea (Sweden). Esflla­ rine, Coastal and Shelf Science 22, 357-369. Underwood, A.J. (1993). The mechanics of spatially repli­ cated sampling programmes to detect environmental impacts in a variable world. Australian Journal of Ecology 18, 99-116.

Whittaker, R.H. (1975). Communities and ecosystems. Macmillan, New York. 385pp. Worthington, D.G., DJ. Ferrell, S. E. McNeill and J.D. Bell (1992). Effects of the shoot density of seagrass on fish and decapods: are correlations evident over larger spatial scales. Marine Biology 112, 139-146.

Van den Broek, W.L.F. (1979). A seasonal survey of fish populations in the lower Medway Estuary, Kent, based on power station screen samples. Estuarine, Coastal and Marine Science 9, 1-15.

Young, P.C. (1981). Temporal changes in the vagile epibenthic fauna of two seagrass meadows (Zostera capricorniand Posidonia australis). Marine Ecology Progress Series 5, 91-!02.

Bureau of Resource Sciences Proceedings 105 DISCUSSION OF SESSION 4

Recorded by M.I.Kangas South Australian Department of Fisheries GPO Box 1625 Adelaide SA 5001

Questions were addressed to individual speak­ to call the physico-chemical attributes an ers and followed by more general discussion. 'ecotome' rather that a habitat, the habitat actu­ ally being within an ecotome. His definition of After the presentation by John Koehn, Pe­ a habitat is one of a fairly restricted area or ter Jackson commented that when looking at the 'patch' which can be defined by a number of key variables determining fish populations in various descriptors. streams we have to accept that these key factors will differ between different river systems and Russel Reichelt commented on the com­ that there is a need for 'regionalisation' of river plexity of systems and the small amount of systems. In addition, biotic interactions need to resources available to study the key factors and be considered. John Koehn agreed and high­ asked the panel to comment on some of the lighted the need to consider introduced species processes needed to filter and select priorities and their interactions. for research. Karen Edyvane pointed out that we should Neil Loneragan described the work that has also be looking at community level indicators, been done in Western Australia regarding like Karr's Index of Biological Integrity. John estuarine systems by defining levels of Koehn responded that to look at the integrity of environmental variation in distinct regions of the system you need to consider the whole systems. The sort of questions they can be system and all linkages, and this knowledge at moving towards is looking at specific habitats all levels is lacking. within a zone. He noted that in estuarine work Jim Puckridge raised the point that one key the linkages are poorly defined between estuaries factor that had been omitted in the preceding and shallow inshore systems. In the case of the discussions was one of temporal variability, Peel Harvey system the future directions would particularly hydrological variability in riverine come from some appropriate ecological environments. This factor needs to be recognised modelling and making predictions and testing as it is one that is commonly under threat. Bryan these predictions. Pierce agreed with Jim Puckridge's comments John Koehn emphasised that research pri­ regarding freshwater and estuarine systems. orities depend on what the question is. Manag­ Murray Macdonald questioned whether ers come up with questions set at various levels, Peter Young' s definition of habitat in terms of either on an ecosystem level or a specific ques­ physico-chemical attributes, without mention­ tion. For example the habitat work conducted in ing species interactions, was intentional or oth­ Victoria was essentially stimulated by funding erwise. Peter Young responded that he prefers of streamflow determination and from this came

106 Bureau of Resource Sciences Proceedings the recognition that we did not have the knowl­ Bryan Pierce highlighted the fact that most edge of the parameters required to plug into of us are working in a 'reactive' mode so we those sorts of models. It was also recognised that cannot collect data that will allow us to 'shape' habitat data were required in order to manage things in the future so that episodes such as that things. In addition a lot of research, particularly with the Murray cod do not occur again. He in freshwater work is externally funded and believed that we need to go beyond a reactive these are specific projects; no-one will fund mode. ecosystem projects. Peter Gehrke commented that there is a Peter Young was of the view that experi­ problem with defining a fish habitat but in all mental management is feasible for freshwater three systems we can group key factors as; and estuarine systems. Modelling, such as that limiting, controlling or masking. We should be proposed in Port Philip Bay and done in West­ able to come up with a suite of variables which ern Australia, will actually identify the critical are major controlling factors in one major habi­ things that we need to know. For offshore situ­ tat type and which factors are limiting. For ations it is still guesswork. It is more likely that some freshwater systems the limiting factors the effects of fishing on the habitat are more may change. He gave an example of this. He important compared to other things impacting then invited the panellists to give a summary of on the habitat. We need to know what the gear what they consider limiting factors and control­ is doing. John Koehn emphasised that in fresh­ ling factors for their various systems. water systems it is the changes to habitat or John Koehn responded that there certainly habitat degradation that are more of a problem are critical and limiting factors in freshwater than fishing. systems. We can group rivers which have simi­ Gina Newton focussed on an issue that had lar attributes such as upland versus lowland. To not been raised previously, linking estuarine determine critical factorswe need to consider and marine environments, that of the retention each species; some factors may involve several of larval and juvenile organisms, related to the species but some factors may affect only one geomorphology of the estuarine mouths in terms species. It is not easy to come up with just a few of the flow regimes. Also the stratification of factors. On further thought he stated that there those waters in estuaries. are some critical stages that could be concen­ trated on, such as the critical factors affecting Peter Jackson brought the discussion back spawning inducement and larval feeding. to the question of the important variables to Neil Loneragan said that for the estuarine measure. He suggested that since there has been systems, looking at the habitat level, seagrass some excellent work in the freshwatersystems and algal species are limited by flowand light by John Koehn and his team in Victoria and regime. Key factors for fish species become Angela Arthington in Queensland, an Australia­ more complex depending on whether you are wide freshwater habitat group be established to considering the community level, recreational see whether certain areas can be agreed on as species, commercial species etc. Factors influ­ needing work. Expanding on Gina Newton's encing fish communities are salinity regime, reference to hydrological regimes he restated distance fromestuary mouth, rainfall and water his earlier comments on classifying rivers ac­ flow, but he was not sure whether these can be cording to their hydrological regime as being a classified as key factors. starting point to putting groups of rivers to­ gether. Due to a lack of resources any work done Peter Young responded that for estuarine should try to look at aspects that are as widely systems, salinity would definitely be a factor. applicable as possible. In the open ocean, zoogeography would play a

Bureau of Resource Sciences Proceedings 107 part as would depth. There is not enough knowl­ Jeremy Prince thought that marine fisheries edge to state key factors there. scientists can learnfrom the freshwater scientist in such areas as methods of describing fish John Glaister tried to focus the discussion habitats. He stressed the need to understand the towards considering when fisheries managers spatial and temporal structure of fish stocks to are making decisions about fish habitats - what lay the framework formeasuring and monitor­ do they need to know? Jenny Burchmore sup­ ing abundance in the field instead of just moni­ ported John Glaister's comments and expanded toring the CPUE (catch per unit effort). as a manager she is confident in the current information available that seagrasses are impor­ Campbell Davies noted that for coral reef tant as fish habitats and that more emphasis communities there is very strong evidence of needs to be placed on other less studied areas habitat preferences. When attempting stock such as the impact of dredging. assessment, spatial heterogeneity must be considered. Roland Pitcher raised the need formodel­ ling to help highlight priorities in research and asked Nmm Hall to explain modelling in more detail. Norm Hall responded that models try to put together people's understanding of proc­ esses in a very simple form. Modelling plays a part in trying to identify the questions you need to ask and the data that are needed, and then trying to put them together and finding areas where the model doesn't actually work. In other words modelling is the formalityof putting your thoughts down on paper, testing them and trying to improve on your knowledge.

Bryan Pierce then tried, as chairperson, to bring the threads of the discussion together. We have tried to elucidate the key factors that link fish and their environment. For all the three environments discussed we know they are com­ plex and that the detailed knowledge of key factors for many species is limited. Any model produced would be preliminary. The only place where habitat is not a major management issue in terms of human impact is in the offshore environment. Everywhere else it is a critical issue and needs to be continually focussed on, whether we do it through modelling and taking the predictions and testing them, or through adaptive management in the field. We need to come up with results that mean more fish in the water because in all habitats we are looking at a continuing decline trend.

108 Bureau of Resource Sciences Proceedings GENERAL DISCUSSION-DAY 1

Recorded by D.C. Smith Victorian Fisheries Research Institute PO Box 114 Queenscliff VIC 3225

Stan Moberly began the discussion with the provide a tool for getting the message across but comment that although we don't know as much it would also act as a guiding framework for about the environment as we would like, we looking at how we are going in a year, five years probably don't appreciate how important our or ten years time. She agreed with Stan Moberly knowledge of its complexities is. He stressed that it is extremely important to get the message the importance of a proactive approach to get­ out there, to create the awareness and profile, ting the information across to the relevant peo­ and to get the involvement and participation of ple, rather than simply reacting through, for the wider community. example, the Environmental Impact Statement Gary Jackson agreed with both speakers. (EIS) process. He commented that not very He said that Phil Cadwallader had written what much discussion has taken place on how we get was wrong with native fish populations 20 years the information across to those who impact ago, yet nothing had really eventuated, except upon the environment. that more populations were under threat and Chairperson Bryan Pierce called for com­ more habitat had been lost. He was concerned ments on the key issue of communication. that in ten years time we should not be in the Barbara Richardson argued that there was an same situation. Information must be in a form initial step before disseminating information: that can be used by fisheries managers and also the need for a structure of where we are going to educate the public. with research and its application. There needs to Rob Lewis, speaking from a manager's be some statement on what are now thought to perspective, mentioned his reverse chair tech­ be the critical driving mechanisms in fish habi­ nique. When, forexample, industry complains tat. This, together with statements by managers or asks for action on a particular issue, he puts on what they consider the major threats, could them in his chair and moves to the other side of form a structure to enable priority setting. It the table and asks them what they would do. He would also allow assessment year by year on suggested that this might be applicable here. He progress. discussed the need to find compatibility and Stan Moberly thought the time was right agreement on our preferred approach, i.e. get­ now and wondered whether the Society was ting our own house in order first. He posed the going to take a lead approach in dealing with this question as to how he, as a fisheries manager, issue. Barbara Richardson responded by saying can start to influencethe decision makers. that she was not proposing delaying this, but In the light of earlier comments about the hoped that an outcome of this workshop would Society's role, John Glaister proposed a small be a "state of our understanding". This might group to meet at the end of the day to develop a

Bureau of Resource Sciences Proceedings 109 Society position that could be discussed on the Chancellors and suggesting that they might per­ final day. Barbara Richardson agreed to chair haps change some of their courses? To what the group and several others were "volunteered". extent can the Directors of Fisheries influence, John Koehn agreed with earlier speakers say, the Directors of Forestry? He commented arguing that it is important that we are involved that increasing our profile in this area could be in the decision-making process, because if we very difficult particularly given Australia's fed­ are not, the best information will not be utilised. eral system. Another approach the Society hasn't His second point was that we always assume really considered is through the media. It can be that people in other fields know more than us. a risky business but it certainly is going directly From his experience that just isn't true. to the people. He mentioned that CSIRO are commencing training for selected staff in deal­ John Koehn went on to describe his own ing with the media, recognising that this is the involvement with forestersand the positive out­ way of the future. Bryan Pierce supported the comes that such interactions can give. Initially need to "sell" our fisheries better. they were uncooperative, and didn't want to hear that, for example, sedimentation was a Dianne Hughes argued that communica­ problem even though they realised it was, but tion between Societies is important. She also eventually they asked for advice on how to stop suggested that an outcome of the workshop the sediments hitting the stream. It was a daunt­ could be a report or review that could be dis­ ing task, because there really aren't the 3 star seminated widely to all groups, including engi­ scientifically replicated 10 year experiments to neers, foresters, government and parliamentary give exact answers. But from the knowledge committees, Universities etc. She stressed the and principles already available, the important importance of the Society setting down its goals points are there. We came up with all sorts of and objectives and stating how these might be things and now there's even a suggestion that achieved. This point was also taken up by Bob we will get another code of forest practice 0' Boy le who supported the need for the Society revised. The foresters have now come to accept to put out a "state of the habitat" repmt. This was that we are the water experts, they are the tree a positive approach, considering that all he had experts and so we are in there. It has taken up a heard so far were comments about how bad huge amount of time but you can have an effect things were. He suggested that a group could and you can change the thinking. However, it is start working towards it over the next year. a long hard education process. We have gone Stan Moberly discussed the American Fish­ some way to getting aquatic fauna, as opposed eries Society's experience with the Forestry to just water, included into forestry studies. Service and the benefits of an integrated ap­ Peter Young reiterated that it comes down proach. Members of the Society together with to "how to influence the decision makers?". He fisheries people in the Forestry Service and mentioned that the Society has a high profile some foresters convinced the Service that cur­ with the fisheries decision makers and is recog­ rent practices had a considerable impact on the nised, for example, by the Standing Committee aquatic environment. This has seen, over the last on Fisheries and Aquaculture. The Society is 6-7 years, the fish and wildlife budget of the consulted on many issues but could probably be Forestry Service increase about four times, and further consulted if it chose to be. Where we their staff of fisheries and wildlife personnel have a low profile, however, is with other groups. also increase dramatically. Although not all the He posed the questions: How many University answers are known, this was a start in the right courses in forestry or agriculture include the direction. Trees will still be cut down, but if they impact of their activities on the aquatic environ­ can be cut in a way that has less impact on ment? Have we considered approaching Vice aquatic resources, that is progress.

110 Bureau of Resource Sciences Proceedings John Koehn mentioned Victorian reports information. For example, it will be technical which included state ofrivers. He remarked that information forthe foresters, and information representing fish has an advantage. People, on the planning process for commercial including foresters, are interested in fish, they fishermen (and presumably the same for fish forthem, eat them etc. But foresters know recreational fishers). about trees and we know about fish, but con­ Peter Gehrke' s view of the day's proceed­ versely we don't know about trees and they ings was that everybody believes that habitat is don't know about fish. He stressed the need to important but there are no definitions on how to bridge this gap in knowledge. He also sug­ delineate where we are going. If our goals are gested that there was a general interest in popu­ not well delineated, how are we going to iden­ lar stories in the media, mentioning Stuart tify the problems we are going to encounter in Rowland on the ABC National program "Aus­ achieving those goals? Scientists have vested tralia All Over" talking about cod, and the interests in learning more and more details videos put out by the Murray-Darling Basin about the systems they are addressing and, from Commission. Information on key species can professionaland numerous other perspectives, also be put in a form that managers can use that is the correct approach. However, fromthe easily. People are receptive to this. Fish scien­ point of view of managing the habitats that tists have to get involved with all groups, espe­ support the fishery, we have got to be prepared cially in freshwaterwhere you have foresters, to take a more reductionist view to the systems engineers and water managers. we are looking at. We will never understand all Mick Olsen endorsed John Koehn's the variables but at least in the conceptual multi-disciplinary approach but cautioned that models that we use we can summarise the state fisheries managers often do not like to see other of knowledge. Even flow charts of some s011 disciplines coming into their area of responsi­ would be of use in providing guide-lines for bility, yet everybody is aiming at sustaining the what we have to do. We have to define the key habitat and wildlife. A further advantage of processes driving the habitats that we are look­ having a multi-disciplinary thrust at maintain­ ing at. In many of the fields we are dealing with, ing habitat is that you may be able to get extra and from a modelling perspective, answers to funds. within an order of magnitude are adequate. As many of our processes operate on a logarithmic Duncan Leadbitter talked about the role of or exponential scale, to try and reach 5 % or l 0% the fishing industry in habitat protection. He resolution is not practicable. We know a lot argued that l O years ago fishermen were more and we can give a lot more advice than we castigated for not being involved in habitat and have been doing to date. In summary, a more now they were zealots. He put forward a word reductionist view is needed in the way we of caution, however, in terms of education, on approach research for management as we get the top down approach that science is the down to defining what is the important scale of fountain of all knowledge. He argued that he sustaining habitats for specific fisheries issues. had wasted 6 months when starting his job of trying to convince fishermen of the importance Bryan Pierce concluded the discussion by ofhabitat because they already knew this. What agreeing that we have got to set some goals and they needed to know was how to approach that in the past we haven't. This is, perhaps, Government. Fishermen need training in how why we aren't talking within the same frame­ the planning system works, how environmental work all the time. Key factors - clearly we do impact assessment works, how they can have not have them - and a reductionist view would their say and how they can get habitats protected. certainly get us there as long as they are criti­ So different sectors will need different cally tested. Picking up Stan Moberly's point,

Bureau of Resource Sciences Proceedings 111 he thought that probably the most critical factor that wasn't dealt with in the organisation of today was the issue of communicating whatever we decide, to the public, to make something actually happen. This should be dealt with on the second day of the workshop.

112 Bureau of Resource Sciences Proceedings SESSION 5

IMPACT OF HUMAN ACTIVITIES ON HABIT AT AND FISHERIES

Session Chairperson: C.M. Macdonald Session Panellists: M. Mallen-Cooper G.P. Jenkins R.A. Campbell Rapporteur: P.C. Coutin 114 Bureau of Resource Sciences Proceedings CHAIRPERSON'S INTRODUCTION

C. M. MacDonald Marine Science Laboratories P.O. Box 114 Queenscliff VIC 3225

Good morning and welcome to Session 5 on Before introducing the panellists for this Day 2 of this workshop. During yesterday after­ session, I would like to share with you a brief noon's sessions we had extensive discussions impression of the impact of human activities on on the relationship between aquatic organisms coastal marine and estuarine habitats and and their habitats, and on the possible impacts fisheries in the USA as a prelude to discussion of various types of human activities on these of the Australian situation. This impression is relationships. This morning I hope to further based on informationcollected over more than develop the theme of the workshop by broaden­ 20 years by the US National Marine Fisheries ing the discussion to consider linkages not only Service (NMFS) as part of its National Habitat between various human activities and habitat Conservation Program. I was fortunate enough alteration, but also between such habitat altera­ to attend an internationalcoastal management tions and fluctuationsin the abundance or avail­ symposium (Coastal Zone '89) in the US at ability of economically important species. which this information was presented, and I subsequently obtained a transcript of the The main objectives of the discussion will presentation and permission to cite the be: information, courtesy of the Office of Protected to identify major categories of human­ Resources and Habitat Programs, NMFS, induced impact on aquatic habitats; Washington D.C. to assess, for each of these major catego­ The overwhelming impression from the ries, the quantity and quality of scientific NMFS presentation was that as population evidence for linkages between human ac­ growth - and therefore increased urban, indus­ tivities, habitat alterations and fluctuations trial and agricultural activities - has occurred in fishery resources; and along the US coastline over the last 100 years or more, so have there been increased problems in • to identify (if possible) strategies for dem­ maintaining the health and productivity of in­ onstrating these linkages in order to con­ shore and coastal aquatic habitats and living vince governmentsand the general public resources. Over 110 million acres, or more than of the importance of protecting and main­ 50%, of total US wetland habitats had been lost taining aquatic habitats. up to the mid-1970's. The total loss of coastal I will begin by presenting a list of human­ wetlands is not as severe (about 20% up to the induced impacts on aquatic habitats which are mid-1970s), but the rate of loss has accelerated considered to be of some significance in the to more than 100,000 acres per year in recent Australian context (Table 1). This list can be years. This is of particular concernwhen about added to or modified during the course of the 70% of all US commercial fishery resources are discussion. estuarine-dependant, and estuarine-dependant

Bureau of Resource Sciences Proceedings 115 species support commercial and recreational fish­ The NMFS presentation concludes by eries each estimated to generate economic ben­ stressing that while fishpopulations can recover efits of several billion dollars per year. from overfishing, the pollution and/or loss of NMFS fish habitats results in long-te1m and generally The presentation identifies physical irreversible population losses. habitat modification, contaminant loading, ex­ cessive nutrient loading, water diversions/ob­ This sobering impression of the situation in structions, waste disposal, pathogen the USA may not be immediately relevant to us introductions, chemical loading, marine debris, because of Australia's much smaller population dredging and spoil disposal, hydropower and and economy. However, Australia's population forestryand mining as the most important sources continues to grow and, like the USA, we have an of impact on US coastal and inshore marine affluent lifestyle and a strong coastal orienta­ habitats. Specific evidence of the impact of tion. The US trends outlined above can there­ human activities on aquatic habitats and/or fish forebe viewed as an indicator of what is in store populations included: for Australian aquatic habitats and living re­ sources if the population and economic trends of decline of Columbia River Basin salmon recent decades continue. and steelhead trout catches to 16-25% of historic levels following a loss of access by So what do we know of the links between wild fish to 33% of historic headwater human activities, changes in aquatic habitats spawning areas due to hydropower dams; and production of fishery resources in Australia? My experience in drawing together panellists 60-80% decline in striped bass populations for this session suggests that our' knowledge' in in San Francisco Bay followingincreasing this area consists of a great deal of hypothesis, diversion of freshwaterinflows and loss of some circumstantial evidence, and only a small up to 80% of Bay wetlands; amount of rigorous quantitative assessment of 80% or more decline of commercial catches such links. Perhaps some of you in this workshop of striped bass, river herring and American might have a different perception, in which case shad in Chesapeake Bay during 1960-1983. we would like to hear it. This coincides with substantial seagrass loss We will now prime this discussion session associated with excessive nutrient loading, by hearing three Australian case studies of habi­ and with other human-induced habitat modi­ tat change and fluctuations in fishery resources. fications in brackish water nursery areas; Martin Mallen-Cooper will talk about habitat a substantial proportion of US coastal wa­ changes and fluctuationsin the distribution and ters under shellfish aquaculture in the early abundance of freshwaterfish, mainly in eastern 1960s have since been closed - mainly be­ Australian drainages. Greg Jenkins will then cause of contamination from human sew­ discuss the relationship between seagrass loss age effluent. Many of these closed areas and declines in commercial scalefish catches in have high levels of human sewage tracers in Westemport Bay, Victoria. Robert Campbell the sediments; and will then conclude by describing the effects of trawling on marine benthic habitats and fish US coastal areas with the highest human communities on the North West Shelf of Aus­ population densities are also the areas where tralia. It is hoped that these presentations will the highest levels of contaminants (eg. DDT, stimulate general discussion on the relationship PCBs, PAHs) are being found in fish and between human activities, habitat changes and sediments. These are also the areas where fisheries production, which will in tum lead to fish have the highest incidence of cancerous the formulation of findings and/or conclusions growths and other serious diseases. regarding the discussion objectives listed above.

116 Bureau of Resource Sciences Proceedings Table 1. Major categories of human impact on Australian aquatic habitats Freshwater: Estuaries/Bays: Physical habitat loss (flow regulation, Physical habitat loss (shoreline dredging and development, channelisation etc.) spoil disposal, etc.) Excess nutrients/eutrophication Excess nutrients/eutrophication Erosion/sediment deposition Catchment erosion/sediment deposition Salinisation (land use practices) Species introductions/translocations Contaminants ( organic and inorganic) Physical impact of fishing methods Species introductions/translocations Contaminants (including heavy metals and hydrocarbons)

Marine: Global: Physical impact of fishing methods Greenhouse effect/climate change Hydrocarbons (oil) Ozone depletion/UV damage Waste dumping/debris Sewage/industrial effluentdisposal

Bureau of Resource Sciences Proceedings 117 HABITAT CHANGES AND DECLINES OF FRESHWATER FISH IN AUSTRALIA: WHAT IS THE EVIDENCE AND DO WE NEED MORE?

M. Mallen-Cooper Fisheries Research Institute P.O. Box 21 Cronul/aNSW 2230

Introduction and distribution of freshwaterfish in Australian rivers (e.g. Lake 1971; Cadwallader 1978; Pollard Many freshwaterfish species in Australian river et al. 1980; Merrick and Schmida 1984; Koehn systems have declined in their range and abun­ and O'Connor 1990;Lloydetal. 1991).However, dance during the last 100 years and habitat what is the real evidence linking the two? changes are frequently considered to be the major cause. In this paper I am going to briefly In Table 1 have been listed the major ele­ examine the published evidence for these de­ ments of habitat that have been affected by clines, the habitat changes which are implicated, human activities with an estimate of the quality and the quality of the evidence linking the two. of the evidence linking these with declines of native fish in Australia. While there is general consensus among fish biologists that many native freshwaterfishes now have a reduced distribution and abundance compared with pre-European settlement, the Dams and weirs as barriers to fish published evidence is sparse. Records of com­ movement mercial catch have been used to document the The first element of habitat I have listed is decline of Murray cod (Mac11/lochella pee Ii) in 'access' (to suitable habitat), which is a basic New South Wales (Rowland 1989), barramundi need of freshwater fish. In modified river sys­ (Lates ca!carifer) in Queensland (Pollard et al. tems, movement of fish along streams and onto 1980), and silver perch (Bidya1111s bidya1111s) in floodplains is restricted to varying degrees by the Murray-Darling river system (T.J. Johnson dams, weirs, levee banks, road crossings and pers. comm.). In Victoria, museum records, pub­ culverts. In the streams of coastal south-eastern lished reports and interviews with anglers and Australia half of the aquatic habitat has been biologists have been used to document the de­ obstructed by man-made barriers (Harris 1984). cline of Murray cod, trout cod (M. The disappearance of many migratory species macq11ariensis), Macquarie perch (M. above large dams is readily acknowledged, but a11stralasica) and golden perch (M. ambig11a) there are few published studies documenting (Cadwallader 1981; Cadwallader and Gooley these declines in Australian rivers, probably 1984; Brumley 1987). because the evidence linking the adverse im­ Habitat loss and degradation by human pacts of the impoundment on fish migration is activites have been hypothesized by many authors clear-cut. A notable example is the disappear­ as the main cause of declines in the abundance ance of natural populations of golden perch from

118 Bureau of Resource Sciences Proceedings the upper River Murray following the construc­ as an important cue for spawning of native tion of Hume Dam and Yarrawonga Weir (Lake species (Lake 1967; Rowland 1983). The ef­ 1971). Low weirs can be submerged by fectsof river regulation can be direct and obvi­ floodwaters which provide some passage for ous, such as a fish kill below a dam when the fish. However, these barriers still very seriously flow is stopped completely and fish are stranded restrict fish movement. One of the few pub­ (Bishop and Bell 1978). Fish kills have also lished studies demonstrating this is by Harris been reported when floodgates are opened on (1988) who sampled with gill nets above and coastal streams releasing poor quality water below a tidal weir (Liverpool) near Sydney and (Richardson 1981). However, the direct evi­ foundno migratory species above the weir and dence for river regulation causing a decline in abundant fish below the weir. A less quantita­ freshwater fishin Australia is generally absent. tive but notable example of this type of impact Records of fish movement through fishways is the decline of the commercial catch of provide some evidence of declines in fish barramundi in Queensland attributed to tidal movement and abundance due to changes in barrages preventing migration (Pollard et al. flows caused by river regulation. The numbers 1980). Despite the lack of published informa­ of golden perch using the Euston (Lock 15) tion, the restriction of fish movements particu­ fishway in the River Murray have declined by larly at large dams and weirs is obvious and the 43 % over the last 50 years, while the movement links between the human activity, habitat change of silver perch has declined by 93 % (Figure l ). and declines of fish are good. Over the same period the small floods (5,000-10,000 ML/day) that stimulate migration in these fish have declined by approximately River regulation half (Close 1990). In this case, river regulation appears to have reduced the stimulus to migrate, River regulation has had direct and measurable although other factors such as water quality may effectson the flow and temperature regimes of also have contributed. For silver perch, and streams in Australia (Walker 1985; Cadwallader perhaps for golden perch also, the reduced 1986). However the causal links between these numbers provide some quantitative evidence of changes and declines in freshwater fish the decline in their abundance. These declines populations are difficult to demonstrate. The cannot be attributed solely to river regulation, as evidence is usually anecdotal and difficult to this is very difficult to separate from other separate from other changes in habitat. Some habitat changes such as siltation and barriers to evidence is provided by Rowland (1989) who migration. linked the decline of Murray cod in NSW in the 1950's and 60's to the reduction in flooding caused by major dams in the tablelands. Simi­ larly, Harris ( 1988) demonstrated that flooding Changes in water quality was important in the reproduction of Australian In some cases changes in water quality through bass (Macquaria novemarnleata) and linked human activities have produced visible and di­ the decline in recruitment of this species with rect evidence such as fish kills from chemical floodsuppression caused by dams. pollutants. Toxicological studies in Australia Other experimental research on the biology have also produced indirect evidence from labo- of native fish has produced stronger, but still ratory studies of the effectsof pollutants on fish indirect, evidence linking river regulation and (e.g. Baker and Walden 1984; Gehrke 1988). declines of fish. Specifically, floodingand tem­ Sewage and fertilisers have decreased water perature have been identified in fish hatcheries quality through nutrient enrichment and in-

Bureau of Resource Sciences Proceedings 119 creased algal growth, leading to reduced oxygen smothered with a fine layer of silt. River in the water (Williams 1980). In Australia, this channelization directly affects the substrate. has probably changed the composition of fish Although there is much evidence fromresearch communities and reduced the distribution of overseas that channelization is detrimental to some native species, but there appears to be no fish(e.g. review by Swales 1982) the evidence published evidence. for adverse effects on native fish in Australian rivers is limited to one study by Hortle and Lake Fish kills fromacidic water have been de­ (1982). These researchers compared fish of scribed overseas (e.g. Leivestad and Muniz channelized and unchannelized sections of the 1976). In Australia acidic soils and runoff from Bunyip River in Victoria and found that fish inappropriate land use have been implicated in numbers, biomass and species richness were all fish kills but it has only been reported in the reduced in the channelized sections. media and not in the scientific literature. Acidic Channelization, however, is not widespread in water has also been implicated in red-spot dis­ Australia compared with catchment erosion and ease in fish but again there is no published siltation. evidence in the scientific literature. Although there is some indirect evidence fromlaboratory work for the need for high water quality (e.g. Gehrke and Fielder 1988) the evidence linking lnstream cover and riparian vegetation changes in water quality with declines of fresh­ water fish in Australia is generally poor. Instream cover and riparian vegetation have frequentlybeen removed to improve navigation or channel capacity, or for sand and gravel extraction. This imp01tant element of habitat Substrate can be replaced by introduced aquatic plants. Soil erosion resulting from land clearance, agri­ There are only two studies examining the rela­ culture, timber harvesting and other activities tionship between freshwaterfish and instream has led to increased turbidity and suspended cover in Australia; Hmtle and Lake (1983), solids. When these suspended solids settle, the discussed above, and Arthington et al. (1983). substrate of the stream is modified by siltation The latter study related the loss of native aquatic and sedimentation. There is strong direct and plants and the increase in introduced plants in indirect evidence from overseas research that streams near Brisbane to a decline in the distri­ such habitat changes severely affect fish, par­ bution of five native fish species. ticularly the early life stages (Alabaster and Apart from these two studies the direct Lloyd 1980; Campbell and Doeg 1989). evidence linking declines in instream cover and However, in Australia there are only two riparian vegetation with declines in fish abun­ reported studies of the effect of turbidity and dance in Australian streams is poorly docu­ sediment on fish; Richardson (1985) found a mented, although again there is reasonable decrease in Galaxias maculatus populations evidence fromstudies overseas (e.g. Angermeir following forestry operations in southern New and Karr 1984; Fausch and Northcote 1992). South Wales, and Koehn et al. (1991) reported There is, however, indirect evidence through that in artificial conditions, eggs of freshwater life history studies of Australian fishes which blackfish Gadopsis marmoratus, spotted describe the use of habitat by fish and hence the galaxias Ga Iaxi as t/'11 ttace IIs, climbing galaxias inherent value of the habitat beforeit is removed G. brevipinnis and Macquarie perch Macquaria or degraded ( e.g. Pollard 1971; Cadwallader australasica showed high mortalities when and Rogan 1977; Harris 1988).

120 Bureau of Resource Sciences Proceedings Conclusions of activities which are contributing (or have contributed in the past) to the current decline in In other countries there has been considerable fish diversity and abundance. The research pri­ research carried out and published which links orities listed above are essential to this under­ human activities, changes in habitat and de­ standing. clines of freshwaterfish. In Australia there has been little such research published. It may be possible to apply the broad principles fromthe Acknowledgements overseas studies to the management of Austral­ ian freshwaterecosystems, but we still need to I thank Jenny Burchmore, Drs John Harris, Jane carry out and publish research which quantifies Mallen-Cooper and Stephen Swales for com­ the responses of fishspecies and populations to ments on the manuscript. the environmental conditions typical of coastal and inland rivers in Australia. To answer the fundamentalquestions asked by managers, such References as how much of a particular impact is acceptable Alabaster J.S. and R. Lloyd (1980). Water quality criteria in a particular habitat, there is an urgent need for for freshwater fish. (PAO: Butterworths, London). research in the following areas: Angermeier, P.L. and J.R. Karr (1984). Relationships be­ determination of habitat utilisation by fish tween woody debris and fish habitat in a small and derivation of key habitat requirements, warmwater stream. Transactions of the American Fish­ 113, such as instream cover, substrates, role of eries Society 716-726. aquatic and riparian vegetation, and use of Arthington, A.H., D.A. Milton and R.J. McKay (1983). floodplains; Effects of urban development and habitat alterations on the distribution and abundance of native and fresh­ flow needs of fish - for breeding, move­ water fish in the Brisbane region, Queensland. Austral­ ment, dispersal and recruitment; ian Journal of Ecology 8, 87-101. experimental evidence is needed on the Baker, L. and D. Walden (1984). Acute toxicity of copper and zinc to three fish species from the Alligator Rivers levels of silt and sediment tolerated by fish region. Technical Memorandum of the Supervising at all lifestages, and their responses to key Scielltist for the Alligator Rivers Region No. 8, 27 pp. water quality variables; and Bishop, K.A. and J .D. Bell ( 1978). Observations on the fish fish passage requirements - fishways have fauna below Tallowa Dam (Shoalhaven River, New been developed which are suitable for some South Wales) during river flow stoppages. Australian Journalof Marine and Freshwater Research 29, 543- species (Mallen-Cooper 1992), but the re­ 549. quirements of many species are uncon­ firmed or unknown. In addition, a broader Brumley, A.R. (1987). Past and present distributions of golden perch Macquaria ambigua (Pisces: knowledge of the swimming ability of na­ Percichthyidae) in Victoria, with referenceto releases tive fishes is needed to design access onto of hatchery-produced fry. Proceedings of the Royal floodplainsand through culverts and pipes Society of Victoria 99, 111-116. in road crossings. Cadwallader, P.L. (1978). Some causes of the decline in To maintain fish populations which are range and abundance of native fishes in the Murray-Darling River system. Proceedings of the Royal viable in the long-term, and to prevent the fur­ Society of Victoria 90, 211-224. ther decline of populations of threatened spe­ cies, we need to devise new approaches to the Cadwallader, P.L. (1981). Past and present distributions and translocations of Macquarie perch Macquaria management of aquatic and riverine ecosystems australasica (Pisces: Percichthyidae), with particular in Australia. As part of this process, we need to referenceto Victoria. Proceedings of the Royal Society understand the full environmental consequences of Victoria 93, 23-30.

Bureau of Resource Sciences Proceedings 121 Cadwallader, P.L. (1986). Flow regulation in the Murray Koehn, J., B. O'Connor and D. O'Mahoney (1991). The River system and its effects on the native fish fauna. In effects of sediment on fish. Proceedings of the 1991 J.C. Campbell (Ed.) Stream protection: the manage­ annual conference of the Australian Society for ment of rivers for ins/ream uses. [Melbourne]:Water Limnology. Held at Lorne, Victoria. (Abstract). Studies Centre, Chisholm Institute of Technology. Lake, J.S. (1967). Rearing experiments with fivespecies of Cadwallader, P.L. and G.J. Gooley (1984). Past and present Australian freshwater fishes. I. Inducement to distributions and translocations of Murray cod spawning. Australian Journal of Marine and Maccul/ochel/a peeIi and trout cod M. macquariensis Freshwater Research 18, 155-173. (Pisces: Percichthyidae) in Victoria. Proceedings of Lake, J.S. (1971). Freshwater fishes of Australia. Nelson the Royal Society of\lictoria 96 (I), 33-43. (Australia), Sydney. 61 pp. Cadwallader, P.L. and P.L. Rogan (1977). The Macquarie Leivestad, H. and J.P. Muniz (1976). Fish kill at low Ph in perch, Macquaria austra/asica (Pisces: a Norwegian river. Nature (Loud.) 259, 65-72. Percichthyidae), of Lake Eildon, Victoria. Australian Joumal of Ecology 2, 409-418. Lloyd, L., J. Puckridge and K. Walker (1991). The significance of fish populations in the Murray-Darling Campbell, J.C. and T.J. Doeg (1989). The impact of timber system and their requirements for survival. In: harvesting and production on streams: a review. Aus­ Co11serl'(ltio11 in management of the River Murray tralian Joumal Marine and Freshll'ater Research 40, system - making co11serl'(ltio11 co1111t. Proceedings of 519-539. the Third Fenner Conference on the Environment, Close, A. (1990). The impact of man on the natural flow Canberra, September 1989, 86-99. regime. In: The Murray (Murray-Darling Basin Com­ Mallen-Cooper, M. (1992). Swimming ability of juvenile mission: lnprint Ltd, Brisbane Qld.) pp. 61-74. Australian bass, Macquaria novemacu/eata (Steindachner), and juvenile barramundi, Lates Pausch, K.D. and T.G. Northcote (1992). Large woody calcanfer (Bloch), in an experimental vertical-slot debris and salmonid habitat in a small coastal British fishway.A11stralia11Jo11mal ofMarine and Fresh\\'ater Columbia stream. Canadian Joumal of Fisheries and Research 43, 823-834. Aquatic Science 49, 682-693. MerrickJ.R. and G.E. Schmida ( 1984).Australianfresh\\'ater Gehrke, P.C. (1988). Acute cardio-respiratory responses of Fishes (Griffin press: Netley, South Australia). spangled perch, Leiopotherapon 1111ico/or (Gilnther 1859), to sublethal concentrations of zinc, temephos Pollard, D.A. (1971). The biology of the landlocked formof and 2,4-D. Australian Joumal of Marine and Fresh­ the normally catadromous salmoniforrnfish Galaxias water Research 39, 767-774. maculatus (Jenyns), I) Life cycle and origin. Australian Jouma/ of Marine and Freshwater Research 22, Gehrke, P.C. and D.R. Fielder ( 1988). Effects of tempera­ 91-123. ture and dissolved oxygen on heart rate, ventilation rate and oxygen consumption of spangled perch, Pollard, D.A., L.C. Llewellyn and R.D.J. Tilzey (1980). Leiopotherapon 1111icolor (Gunther 1859), (Percoidei, Management of freshwater fish and fisheries. In: An Teraponidae). Joumal Perciformes, papers. Australian Water Resources Council Percichthyidae) in the Sydney Basin. Australian J our­ conference series, No. 4. (Australian Government 39, nal of Marine and Freshwater Research 355-369. Publishing Service: Canberra). H011Je K.G. and P.S. Lake (1983). Fish of channelized and Richardson, B.A. (1985). The impact of forest road unchannelized sections of the Bunyip River, Victoria. construction on the benthic invertebrate and fish fauna Austra/ia,1 Joumal of Marine and Freshwater Re­ of a coastal stream in southern New South Wales. search 34, 441-450. Australian Society for Limno/ogy Bulletin 10, 65-88. Koehn, J.D. and W.G. O'Connor (1990). Biological i11for­ Rowland S.J. ( 1983). Spawning of the Australian freshwater matio11 for management

122 Bureau of Resource Sciences Proceedings Rowland S.J. ( 1989). Aspects of the history and fishery ofthe Murray cod, Macc11/lochel/a peeli (Mitchell) (Percichthyidae). Proceedings of the Linnean Society 4000 ofN.S.W. 111, 201-213. Yearly catch rote Sanger, A.C. (1990). Life history of the two-spined blackfish, Gadopsis bispinos11s, in King Parrot Creek, Victoria. 2000 Proceedings Royal Society of Victoria 102, 89-96. (No. of fish entering fishway Swales, S. ( 1982). Environmental effects of river channel per year) works used in land drainage improvement. Journalof O+---- 1939-1942 1987-1992 Environmental Management 14, 103-126. Walker, K.F. (1985). A review of the ecological effects of Figure 1. Yearly catch rate (mean± s.e.) of golden river regulation in Australia. Hydrobiologia 125, 111- perch and silver perch from the Euston fish way on the 129. River Murray over periods 1939-1942 and 1987- 1992. Williams, W.D. (1980). Water as a waste transport and treatment mechanism: an ecological evaluation. in: An ecological basis for water resource management. 155- 160. (ANU press, Canberra, Australia).

Table 1. Impacts of human activities on fish habitat and the quality of the evidence linking these impacts with declines in fish abundance and distribution in Australia

Quality of evidence for causing decline in native Habitat Human activity fish distribution or abundance access (to habitat) dams, weirs, levee banks good flow and temperature river regulation indirect regimes water quality domestic, industry, some good, some poor agriculture substrate siltation, sedimentation, poor channelization instream cover and de-snagging, increasing poor riparian vegetation channel capacity

Bureau of Resource Sciences Proceedings 123 ECOLOGICAL BASIS FOR PARALLEL DECLINES IN SEAGRASS HABITAT AND CATCHES OF COMMERCIAL FISH IN WESTERN PORT BAY, VICTORIA

G.P. Jenkins, G.J. Edgar, H.M.A. May and C. Shaw Victorian Institute of Marine Sciences and Department of Zoology University of Melbourne P.O. Box 138 Queenscliff VIC 3225

A decline of over 70 % of the seagrass cover in species, such as leathe1jackets (Figure 2) and Western Port Bay occurred between 1973 and grass whiting (Figure 3) where catches in the 1984 (Bulthius et al. 1984; Shepherd et al. l 980's were at historically low levels 1989). The losses occurred predominantly from (MacDonald in press). Although alternative intertidal areas of Heterozostera tasmanica explanations for the declines, such as overfishing, (Bulthius et al. 1984; Shepherd et al. 1989). and changes in fishing effort or larval input, Although the exact causes of this decline are not cannot be rejected, the results are suggestive of known, the major proximate cause was thought a link with seagrass decline forsome species. In to be desiccation and/or high temperatures cou­ contrast, catches of other species such as yel­ pled with a fine coating of adherent mud on the low-eye mullet either showed no signs of de­ leaves reducing light levels (Bulthius et al. cline, or actually increased (Figure 4). King 1984; Shepherd et al. 1989). The underlying George whiting showed a more complex pat­ causes of losses may have included increased tern, with a major peak in catches in the early turbidity and sediment deposition resulting from 1970's declining to approximately pre-peak lev­ catchment erosion and dredging operations, in­ els in the l 980's (Figure 5). A similar early creased emersion at low tide due to changes in 1970's peak was apparent for King George topography and tidal hydrology, and unusually whiting catches in Port Phillip Bay, suggesting high temperaturesoversummer(Bulthius 1983; that factors such as changes in effort, or larval Bulthius et al. 1984). Losses may have been input, were responsible for the peak (C.M. self-perpetuating; initial seagrass death may MacDonald, unpublished). Post-peak catches have led to mudbank erosion, increasing of King George whiting in Port Phillip Bay were suspended solids and sediment deposition in approximately double those of pre-peak levels, adjacent areas. while in WesternPort Bay, pre- and post-peak levels were similar, suggesting a relatively The decline in seagrass cover was paral­ greater decline in Western Port Bay. leled by a decline of about 40 % in total commer­ cial fish catches fromWestern Port Bay (Figure This presentation describes a small part of I; MacDonald in press). Catches in Port Phillip a major research program on juvenile and adult Bay, excluding pilchards for which catches in­ fishes associated with seagrass beds in Port creased rapidly, remained relatively constant Phillip Bay, Western Port Bay and CornerInlet over the same period. Catch declines in Western aimed at identifying possible linkages between Port Bay were particularly apparent for some fish populations and seagrass habitats. For the

124 Bureau of Resource Sciences Proceedings purposes of this presentation we will concen­ The diets of grass whiting were dominated by trate on the distribution, abundance and diets of seagrass-associated epifauna, mainly molluscs the four species described above to investigate and crustaceans (Figure l IB). The smallest possible reasons for the patterns of decline or King George whitingjuveniles consumed crus­ otherwise of commercial catches in parallel tacean plankton which was quickly replaced by with seagrass loss. crustacean epifauna (Figure 12A), consisting mainly of groups such as epibenthic harpacticoid Results are described for sampling con­ copepods, mysids and tethygeneid amphipods, ducted in 1989/1990 at three sites in Swan Bay which would tend to be concentrated in and one site on the adjacent coast of Pmt Phillip unvegetated patches amongst seagrass beds. Bay (Figure 6). Seagrass and unvegetated habi­ Larger individuals consumed soft-sediment tats were sampled at each site. Sites at Queenscliff crustacean and polychaete infauna (Figure 12A). and St Leonards were adjacent to the shoreline The diets of small juveniles of yellow-eye whilst sites at Tin can and North Jetty were in mullet were dominated by planktonic crustacea; deeper water (1 m MLWS). Dietary studies however, the diets of larger individuals were were conducted on fish collected at three sub­ composed mainly of algae and seagrass-associ­ tidal sites in Western Port Bay; Rhyll, French ated epifauna (Figure 12B). Island and Tooradin. Six-spined leatherjackets and grass whiting Field sampling was conducted with fine­ are obviously highly dependent on seagrass in mesh seine nets of 10 and 15 m length and 1 mm terms of habitat and diet. These species were mesh. The nets were small enough to selec­ not found to settle in areas where seagrass has tively-sample specific habitats. When nets were been lost and replaced by unvegetated habitats. deployed from a small boat, ropes were hauled Food available in unvegetated habitats is using detachable weights to stop the net from probably also unsuitable for these species rising from the bottom until completely although this hypothesis would be difficult to retrieved. test. In general, the parallel decline between Small juveniles of six-spined leatherjacket seagrass and populations of these species is not (Figure 7) and grass whiting (Figure 8) were surprising. almost exclusively collected from subtidal The link between seagrass and King George Heterozostera beds. Both species recruited di­ whiting is more subtle. Although post-larvae of rectly to seagrass in the spring/summer (Figures this species mainly recruit to and feed in 7 and 8). King George whiting recruited to unvegetated patches, it is likely that seagrass unvegetated patches amongst subtidal detritus would lead to elevated abundances of Heterozostera in Swan Bay in spring, and older prey species, possibly leading to elevated growth juveniles were collected in reasonable numbers and survival of juvenile whiting. Swan Bay, fromthe near-shore Queenscliff site in Febru­ with its greater amounts of macrophyte detri­ ary /March (Figure 9). Yellow-eye mullet were tus, has already been shown to support higher collected at the near-shore St Leonards and meiofaunal abundances, and feeding rates of Queenscliff sitesand were never collected at the juvenile flounder,on unvegetated habitats com­ deeper subtidal sites (Figure 10). This species pared with Port Phillip Bay (Shaw and Jenkins tended to occur over unvegetated sand at St 1992). The infauna consumed by older indi­ Leonards, but there was no obvious habitat viduals may also be more abundant in preference at Queenscliff. unvegetated sediments enriched by macrophyte The diets of six-spined leatherjackets were detritus. Although decreased prey abundances dominated by seagrass associated biota, includ­ due to loss of seagrass may be linked to the ing both plant and animal material (Figure 11 A). greater post-peak decline in catches of King

Bureau of Resource Sciences Proceedings 125 George whiting in WesternPort Bay relative to the particular values of interest. For example, in Port Phillip Bay, in general, catches of this Port Phillip Bay, the seagrass habitats which species may also be strongly influenced by other would be preserved to maximise recruitment of factors. In particular, recruitment of King George economically-important fish species would be whiting is dependent on larval input fromBass different to those preserved to maximise the Strait, and could be greatly influenced by overall diversity of fish species. interannual variability in Bass Strait current An important question is how to convey patterns (Jenkins and May, unpublished). informationsuch as that presented here to coastal Juvenile yellow-eye mullet were not de­ managers and others who may influencepossible pendent on seagrass for habitat or diet, appar­ impact on important habitats. Scientists are ently foraging in shallow, near-shore areas for often reticent to become involved with the media; crustacean zooplankton, irrespective ofbenthic their views are often presented less than habitat. Although older individuals consumed faithfully. However, other user or interest groups some seagrass-associated epifauna, this linkage which are perceived by the public to conduct was apparently not critical to feeding success of 'research' have a strong voice in the media. this group. Although the sentiments expressed by such groups may be laudable in terms of habitat To summarise, the strong parallel decline protection, unfortunately the information in fish catches and seagrass loss occurred in presented is often highly erroneous. A case in species which were specifically adapted to life point was recent comments on the proposed in a seagrass habitat. Species with a reduced relocation of a chemical storage facility from ecological link with seagrass habitat did not Coode Island, near Melbourne,to Point Wilson, show a clear parallel decline with seagrass. The near Geelong, on Port Phillip Bay. Claims were post-peak decline in King George whiting made by a lobby group on prime-time television catches was greater in Western Port Bay than news that most of the seagrass beds in Port Port Phillip Bay, suggesting that the link be­ Phillip Bay were located at Point Wilson and tween seagrass habitat and juvenile feedingmay that these beds formed the basis of the food be of imp01tance, although the patternwas domi­ chain for dolphins in the bay. These claims were nated by other factors. patently false and endangered the reputation Work such as that described above identi­ and standing of scientists in general. Scientists fies key factors which may vary with species, could certainly do no worse than these groups. areas and times. However, there may also be Perhaps professional scientific organisations useful broad patterns which may help determine should employ scientists trained specifically in which habitats should be protected for fisheries media relations to convey correct information production purposes. For example, on a bay­ to the public. wide scale, seagrass beds in Port Phillip Bay of similar structure vary in levels of recruitment depending on hydrodynamics (Jenkins, unpub­ lished). This situation is similar to that de­ Acknowledgements scribed in New South Wales estuaries (Bell and We thank Murray MacDonald, Victorian De­ Westaby 1986; Bell et al. 1987). It may be partment of Conservation and Natural Re­ possible to predict which areas will receive high sources, for comments on the manuscript and recruitment using hydrodynamic modelling for providing data on fish catches in Western (Jenkins and Black, unpublished). Port Bay. Funding for this research was pro­ Determining priority in preservation of vided by the Fishing Industry Research and habitats such as seagrass beds will depend on Development Council.

126 Bureau of Resource Sciences Proceedings References Bell, J.D. and M. Westoby (1986). Variation in seagrass height and density over a wide spatial scale: effects on common fish and decapods. J. Exp. Mar. Biol. Ecol. 104, 275-295. Bell, J.D., M. Westoby and A.S. Steffe (1987). Fish larvae settling in seagrass: do they discriminate between beds of different leaf density? J. Exp. Mar. Biol. Ecol. 111, 133-144.

Bulthius, D.A. (1983). A report on the status of seagrasses in Western Port in May 1983. Marine Science Labo­ ratories, Queenscliff, Victoria. InternalReport No. 38, 5 pp. Bulthuis, D.A., D.M. Axelrad, A.J. Bremner, N. Coleman, N.J. Holmes, C.T. Krebs, J.W. Marchant and M.J. Mickelson (1984). Loss of seagrasses in WesternPort. Progress Report No. I, December 1983 to March 1984. Marine Science Laboratories, Queenscliff, Vic­ toria. Internal Report No. 73, 10 pp.

MacDonald, C.M. (1991 ). Fluctuations in seagrass habitats and commercial fish catches in Westernport Bay and the Gippsland Lakes, Victoria. In Recruitment Proc­ esses, Australian Society for Fish Biology Workshop, Hobart, 21 August 1991, D.A. Hancock (ed.), Bureau of Rural Resources Proceedings No. 16, AGPS, Can­ berra. Shaw, M., and G.P. Jenkins (1992). Spatial variation in feeding, prey distribution, and food limitation of juve­ nile flounder, Rhombosolea tapirina Giinther. J. Exp. Mar. Biol. Ecol. 165, 1-21. Shepherd, S.A., A.J. McComb, D.A. Bulthius, V. Neverauskas, D.A. Steffensen and R. West (1989). Decline of Seagrasses. In A.W.D. Larkum, A.J. McComb and S.A. Shepherd, Biology of Seagrasses. Elsevier, Amsterdam.

Bureau of Resource Sciences Proceedings 127 300

200 0T N N E s 100

Beginning of reported seagrass decline 0 +------,-----,-----..------.------.------'-,-----.--- 1910 1920 1930 1940 1950 1960 70/71 80/81 YEAR Figure 1. Annual catches of commercial finfish in WesternPort Bay. 30

Beginning of reported seagrass decline

20 0T N N E s 10

0 +---.---r--.--..-....--.--r---,--.-.:...--r--r-..-....--.--r--,---r---.--.---,---r--r=;-...., 1960 65/66 70/71 75/76 80/81 85/86 YEAR Figure 2. Annual catches of leatherjackets in WesternPort Bay. 50

Beginning of reported seagrass decline 40

T 30 0 N N �20

10 ------

0 +---r----,.---,---,--..-...... --,,---,--,--'--,--,----,--r---r----,.---.---,--..---,----,,---,--,--..-.....---, 1960 65/66 70/71 75176 80/81 85/86 YEAR Figure 3. Annual catches of grass whiting in WesternPort Bay.

128 Bureau of Resource Sciences Proceedings 60

Beginning of reporte� seagrass decline

40 T 0 N N E s 20

0 ....--.----.-..---,.-,--""T"--"'T'"-- .....--.- ...... - -....._,.---.- ,--""T"---,,---,---,--,---, 1960 65/66 70f71 75(76 80/81 85/86 YEAR Figure 4. Annual catches of yellow-eye mullet in Western Port Bay.

Beginning of reported seagrass decline

6 T 0 N N E s 3

o L....-,_....,,--,,__,..__,..--,r---r-��..--,__,.--.---.---.----.--..::::;:::::;::::;:::::;::::;::::;_, 1960 65/66 70(71 75(76 80/81 85/86 YEAR Figure 5. Annual catches of King George whiting in Western Port Bay.

Bureau of Resource Sciences Proceedings 129 Bass Strait

St Leonards

Swan Bay 0 Port Phillip Bay

38 ° 15 Is

0 2 Kilometres

° 144 40 I E Figure 6. Location of sampling sites in Swan Bay and Port Phillip Bay, Victoria, fromwhich juvenile fish were collected. Insets: Location of Port Phillip Bay on the Australian coast, and location of Swan Bay in Port Phillip Bay.

130 Bureau of Resource Sciences Proceedings 20 18 16 14 12 10 North Jetty 8 6 4 2 0

20 18 16 14 12 Tin can 10 8 6 4 2 0

10 8 St Leonards 6 4 2 0 -1---a::�,--=::::o,:::::�:::::tit--.-o--o�---0----..---,

10 8 6 Queenscliff 4 2 0 SON DJ F MA M J J A S Month Figure 7. Abundance of juvenile six-spined leatherjackets in seine-net samples. Open circles, unvegetated habitat; closed circles, seagrass habitat.

Bureau of Resource Sciences Proceedings 131 20 18 16 14 North Jetty 12 10 8 6 4 2 0

20 18 16 - 14 ro 12 Tin can 10 6 8 Q) 6 ro 4 2 ro 0

10 8 6 St Leonards 4 2 0

10 8 Queenscliff 6 4 2 0 1--(J--(.:J--U--0--0--0---0--0-0--0--0--0----,--, S ONDJ FMAMJ J AS Month Figure 8. Abundance of juvenile grass-whiting in seine-net samples. Open circles, unvegetated habitat; closed circles, seagrass habitat.

132 Bureau of Resource Sciences Proceedings 80 No th Jetty 70 r 60 50 40 30 20 10 0 «l

Q) 40 Tin c n C «l 30 a C 20 «l

«l 10 Q) ::z: 0

t e on ar s 1:]+ --.--�•�-••=�•i,----.---,----.---,--S- �L- _ _ r -d -.----,

40 Queen cliff 30 s 20 10 0 A A s 0 N D J F M M J J Month Figure 9. Abundance of juvenile King George whiting in seine-net samples. Open circles, unvegetated habitat; closed circles, seagrass habitat.

Bureau of Resource Sciences Proceedings 133 North Jetty 10

5

0

10 Tin can 5 -0—0- 0

(0

a? 0 I J3 St Leonards ~VS

"> CD

10 i Queenscliff

5

0 SONDJ FMAMJ^^^ J AS Month

Figure 10. Abundance of juvenile yellow-eye mullet. Open circles, unvegetated habitat; closed circles, seagrass habitat.

134 Bureau of Resource Sciences Proceedings A. □ 100 seagrass 90 II] algae IE 80 ascidean � sponge Q) 70 p;j bryozoa '5 60 Q) □ other epifauna 50 «! El polychaete infauna 'E 40 ■ Q) polychaete epifauna 30 Q) □ mollusc infauna a. 20 � mollusc epifauna 10 Ill crustacean infauna 0 ■ crustacean epifauna .01 .025 .063 .160 .40 1 2.5 6.3 16 40 100 250 630

Fish weight (g)

B.

100 0 seagrass 90 [;:I fish epibenthic Iii!!! polychaete infauna 80 Q) polychaete epifauna '5 70 ■ Q) L'S mollusc plankton 0) 60 «! □ mollusc infauna 50 � mollusc epifauna 40 II crustacean infauna Q) 30 crustacean epifauna a. 20 ■ 10 0 .01 .025 .063 .160 .40 1 2.5 6.3 16 40 100 250 630

Fish weight (g)

Figure 11. Dietary composition of fishes from WesternPort Bay. A. Six-spined leatherjacket, B. Grass whiting.

Bureau of Resource Sciences Proceedings 135 A

100 90 80 © 70 DID other infauna '5 60 la polychaete infauna Q) 11 polychaete epifauna 0) 50 CU El crustacean plankton 40 Q) 11 crustacean infauna 30 ■ Q)e crustacean epifauna 20 10 0 .01 .025 .063 .160 .40 1 2.5 6.3 16 40 100 250 630

Fish weight (g)

B.

100 nm ascidean 90 � seagrass 80 © II] algae '5 70 13 other epifauna Q) 0) 60 la polychaete infauna 50 ■ polychaete epifauna 40 □ mollusc infauna Q) 30 lzl mollusc epifauna El crustacean plankton 20 10 a crustacean infauna ■ crustacean epifauna 0 .01 .025 .063 .160 .40 1 2.5 6.3 16 40 100 250 630

Fish weight (g) Figure 12. Dietary composition of fishes from WesternPort Bay. A. King George whiting, B. Yellow-eye mullet.

136 Bureau of Resource Sciences Proceedings EFFECTS OF TRAWLING ON THE MARINE HABITAT ON THE NORTH WEST SHELF OF AUSTRALIA AND IMPLICATIONS FOR SUSTAINABLE FISHERIES MANAGEMENT

K.J. Sainsbury, R.A. Campbell and A.W.Whitelaw CS/RO Division of Fisheries GPO Box 1538 Hobart AST 7001

Introduction An early reference to this problem appeared in 'Guide to the Fishmarket', written by Dr. Fish resources may be used in a variety of Bellamy, a Cornishman,as long ago as 1842. ways. The policy challenge formanagement is to allocate these resources between competing "Fishing, taken generally, interferes in the uses when members of the community with slightest way with the habits of the crea­ rights of access wish to use them in incompatible tures in question; but the employment of a ways. Making a management decision will trawl, during a long series of years, must involve compromise between optimising the assuredly act with the greatest prejudice community benefits fromvarious users of these towards them. Dragged along with force resources and minimising the detrimental over considerable areas of marine bottom, effectsresulting fromeach type of use, so as to it tears away, promiscuously, hosts of infe­ maximise the chances oflong-term sustainable rior beings there resident, besides bringing use of the resources. For most fish resources, destruction on the multitudes of smaller however, there is considerable uncertainty fishes, the whole of which, be it observed, about both the dynamics of the resource and are the appointed diet of those edible spe­ the effects on it of exploitation, both direct or cies sought as human food. It also disturbs indirect. Furthermore, there is the need to and drags forth the masses of deposited ova identify the linkages between the fishresources of various species. An interference with the and the habitats which support and nourish economical arrangement of creation, of such them. magnitude and of such duration, will here­ after bring its fruitsin a perceptible diminu­ Threats to fish resources in the past have tion of these articles of consumption for focused on the problems of overfishing, with which we have so great necessity. The trawl management responses leading to constraints is fast bringing ruin on numbers of poorer being placed on fishing operations, most orders requiring the most considerable notably through strategies to limit harvest rates. attention." More recently however, there has been concern about the destruction of the habitats which are Today, sustainable utilisation of our ma­ required to support many of our fish resources. rine resources has become a high priority. While Generally, this concern has focused on the the concerns about sustainability may not be effects of fishing itself on the marine habitat. new, the need to deal with them effectively has

Bureau of Resource Sciences Proceedings 137 perhaps never been greater because of increasing hard to determine. Typically, ecological theory demands placed on marine resources. Although can be used to derive a number of different management decisions are made in the knowl­ hypotheses about the mechanisms and dynamics edge of the 'best available scientific advice', of change that are all consistent with the obser­ individual decisions are often still demonstrated vations of an exploited community. However, to be incorrect by the excessive depletion of there is considerable uncertainty about the mecha­ some fish resources. nisms which should be emphasized in a commu­ In this paper some of the issues concerning nity model and there are also limitations imposed sustainable use of the marine fish resources by the informationavailable. Consequently, pre­ through sustaining their habitat are illustrated. diction of a marine community's response to The paper is in three parts. The first identifies changes in fishing activities resulting fromman­ some of the problems facing managers of Aus­ agement decisions can remain highly uncertain. tralia's tropical marine fish resources, the second While much attention in the past has fo­ reviews the North West Shelf fishery and de­ cused on the fisheries in temperate Australia, scribes some of the changes to the ecological within the last decade the tropical fisheries of communities in this region, and the third de­ northern Australia have been receiving more scribes both the research and the management attention. Unlike the fisheries in temperate wa­ approach taken in this region. While much of this ters, Australian tropical fisheries are normally has been described elsewhere (see Sainsbury characterised by a large number of species (gen­ 1987; 1988; 1991), the focus here will be on both erally several hundreds) in which commercial the effectsof trawling on the marine habitat and interest is usually shown in only a small portion. the relationship between this habitat and the fish In addition to the monitoring difficulties caused species composition found on the North West by this high species diversity, the biology of Shelf. most species is largely unknown and there are numerous interactions between the species them­ selves. While predator-prey relationships and Tropical multispecies fisheries competition forfood resources will be important in determining the response of the community to 1. The management problem exploitation, the actual role these interactions It is widely recognized that fishing activities play in the dynamics of the community can, at modify the structure and dynamics of ecological most, only be guessed at. Finally, the fishing communities. For example, changes in the rela­ mortality is usually not equal forall species in tive abundance of species in exploited communi­ the community and can be highly influencedby ties are common (Hempel 1978; Cushing 1980). the targeting behaviour of the fishers.For exam­ Furthe1more, the decrease of a few species may ple, some species are specific to a particular be critical if these are the only ones catchable or depth range and if this depth range is highly marketable. On the other hand, widespread targeted by the fishing effort, the fishing mortal­ changes in community composition may be ir­ ity on these species can be high while it remains relevant if most species are catchable or have low on the more widespread species (Sainsbury similar market value. Unfortunately the changes 1982). that happen to communities which include ex­ ploited species are not reliably predictable, and These featuresof tropical multispecies fish­ consequently the economic and social effects of eries combine to increase the uncertainties in such changes are also not reliably predictable. In scientific advice to managers. A common ap­ most situations the dynamics of marine commu­ proach to management under uncertainty is the nities are poorly understood and reasons forthe 'certainty equivalent' approach in which a 'best observed changes in an exploited community are model' of the resource is selected as the most

138 Bureau of Resource Sciences Proceedings likely of the available possible models and used fish stocks of the genus Lethrinus. During the to derive management actions that are then next three years, over seven thousand tonnes of applied to the resource as a whole. Alterna­ this genus were caught with a catch rate around tively, consideration can be given to anumberof 500 kg/hour. Species of this single genus com­ alternative ecologicalinterpretations of the avail­ prised about half of the catch. In 1972 Taiwan­ able data, and the consequences of the possible ese pair trawlers began operations in the area. management options can be evaluated across all The fishing was initially very intensive with these alternative models. With the 'certainty annual catches of between 20,000 and 30,000 equivalent' approach the resource is managed tonnes for the first five years. The retained catch as if the most likely available model is true; it mostly comprised the genera Nemipterus, ignores the uncertainties in understanding about Saurida, Lutjanus and Lethrinus. In 1979 the resource dynamics and usually results in the area came within the Australian Fishing Zone whole resource being treated under the same and consequently under Australian manage­ management regime. This can increase the risk ment. While the Taiwanese continued to trawl to the resource if an error is made, and future under a licence arrangement with the Australian observations of the resource usually have little Government,a small domestic trap fisherybe­ power to discriminate between different hy­ gan operation in the westernpart of the shelf in potheses about resource dynamics because pos­ the early 1980's mainly in areas subjected to sible control variables are confounded. Another little trawling (Moran et al. 1988). approach is based on the methodology devel­ The Taiwanese continued to fish the North oped by Walters and Hilborn(1976; 1978) and West Shelf until 1989, by which time a small Walters ( 1986) for management of resources domestic trawl operation had also become es­ with poorly known dynamics. This approach, tablished. However, in this time several changes often termed 'actively adaptive management', to the biotic community on the Shelf had taken attempts to develop a 'reasoned empiricism' by place. First, a major change within the species managing the resource in a way which permits composition of the fish catch was observed, accelerated identification of the response of the although the total catch rate of the trawl fishery resource to exploitation and provides guidance remained relatively constant. During the initial to the selection of long-term management op­ years the larger species groups, dominated by tions. In the following we discuss the applica­ the genera Lutjanus and Lethrinus, accounted tion of this actively adaptive management for 40% to 60% of the catch, while two other approach to a tropical fish community off north­ genera, Nemipterus and Saurida, together com­ westernAustralia. prised around 10%. By the mid-1980's, how­ ever, this situation had reversed with Lutjanus 2. The North West Shelf-A case study andLethrinus species comprising about 10% of The characterof Australia's tropical multispecies the catch, and Nemipterus and Saurida around fisheries and the related management problems 25%. Secondly, the demersal habitat of the are well illustrated by the fishery located on Shelf was also known to have altered during this Australia's North West Shelf region (Figure 1). period. The quantity of epibenthic fauna (mostly The area supports a diverse and productive sponges, alcyonarians, and gorgonians) caught demersal fish community and has been fished in trawls was observed to be considerably less mostly by foreigndistant-water fleets (Sainsbury than that recorded prior to and during the early 1987). development of the pair trawl fishery. Based on Major commercial fishing first took place research data, the average catch rate of sponges on the North West Shelf between 1959 and 1963 fell from around 500 kg/hour to only a few when Japanese sterntrawlers targeted the large kilograms/hour (Sainsbury 1987).

Bureau of Resource Sciences Proceedings 139 Changes in the relative species composi­ i) environmentally-induced changes in the fish tion of catches on the North West Shelf was of community, independent of the fishery; little consequence to the Taiwanese pair trawl ii) multiple, independent responses by the fish fishery, as all retained species had a similar species to exploitation; commercial value (Liu and Lai 1980). How­ ever, the domestic Australian fishingoperations iii) alteration of biological interactions, such as have no market for Nemipterus and Saurida, predation and competition, due to fishing; and rely heavily on Lethrinus and Lutjanus iv) indirect effects of fishing such as habitat species for commercial viability. With the intro­ alteration. duction of Australian management after 1979, options for maximising the involvement of the While the NWS is influencedby the oceano­ domestic industry were considered, including graphic phenomenon known as the El Nifio­ trap fishing. Expansion of the trap fishery, how­ SouthernOscillation, the precise nature of changes ever, seemed possible only if there was a return in the community dynamics on the Shelf in re­ to something like the historical fishcommunity sponse to these events remains unknown and composition. Furthermore, the poor state of quantitative models based on hypothesis (i) could knowledge about the resource dynamics made not be developed. Changes of type (ii) are possi­ prediction of the resource's response to major ble and involve highly density-dependent popu­ alterations in the historical management regime lation parameters (Sainsbury 1987) for which highly uncertain. It was not clear whether or not simple models could be developed. Ecological the fish community could recover its earlier theory offers numerous possible mechanisms composition or what management actions would which could be used to generate simple models to be best in attempting a recovery. test hypothesis (iii). Less was known, however, about the rela­ 3a. CS/RO Study-1982-1983 tionship between the fish stocks and their habitat, A central management issue arising from the notably the habitat provided by demersal fish community changes observed on the North epibenthic organisms. To examine habitat usage West Shelf (NWS) was the fact that while the by the major fish types a 35 mm camera system species composition had initially been attrac­ with two illuminating strobes was fitted to the tive commercially, the present day composition head rope of the trawl gear, and a colour photo­ was not. Given this situation, three questions graph was taken every 24 seconds for the dura­ arose in response to the needs of management: tion of each 30 minute trawl. From these photographs the major habitat types were identi­ 1) What caused these changes in species com­ fied, based on the presence or absence of large position? epibenthic organisms (> 25 cm along the major 2) Is it worth trying to reverse the change? axis), and the association between fish and habi­ tat was calculated. The results showed that, in 3) If recovery is attempted, what management general,Lutjanus and Lethrinus species occurred strategy should be followed? predominantly within those habitats which con­ Little was known about the fish communi­ tained large epibenthic organisms, while ties on the NWS at this time and so the CSIRO Nempi terus and Saurida species favored the open Division of Fisheries undertook an intensive sandy habitats. If these results are indicative of a two year study during 1982 and 1983. As a result dependence of certain fish species on certain of this research a series of alternative hypoth­ habitat types, then alteration of the relative amount eses were developed to explain the observed of each habitat in an area by trawling would alter change in community composition. These were: the fish community composition in that area.

140 Bureau of Resource Sciences Proceedings Either separately or together, hypotheses The monitoring was based on a stratified (ii), (iii) or(iv) are able to explain the changes in sampling strategy with 105 randomly located fish species composition observed on the NWS. thirty minute trawls undertaken during the same However, each of these possible causes of change season each year. A photographic transect was can have different management implications. If conducted for each trawl to monitor the habitat the management objective is to maximise the (as discussed earlier). A video camera was used catch of Lutjanus andLethrinus species, and the during some trawls to determine the effects of main cause of the current decline in these spe­ the trawl gear on epibenthic organisms. cies is the loss of large epibenthic habitat (hy­ Data from the western zone, which was pothesis iv) and/or trawl-induced changes in closed to commercial trawling forthe duration competitive/predation interactions (hypothesis of the experiment (from Oct. 1985-Figure 1) iii), then there would be scope for expansion of shows that there was an increase in both the the trap fishery to replace trawling with an combined populations ofLutjanus andLethrinus expectation of recovery of the associated habitat species (Figure 2a) and the abundance of both and/or a returnto the high carrying capacities of large and small epibenthic organisms (Figure these species. On the other hand, if the historical 2b). Recovery of the small epibenthic organisms decline in catches of Lethrinus and Lutjanus has been fairly rapid, but recovery of larger species is because these stocks have intrinsi­ epibenthic organisms is much slower. This indi­ cally low productivity (hypothesis ii), then the cates that there will be a considerable time lag scope for expansion of domestic fisheries of any after trawling ceases before recovery of large kind is limited. epibenthic organisms is substantial. Within the zone in which commercial trawling continued 3b. Experimental management scheme- throughout the experimental period (Figure 1), 1986-1991 the opposite trends are observed. Except for the To clarify the possible dynamics underlying the year 1990 (where the catch data are influenced multispecies trawl fishery on the NWS, an ex­ by two very large catches within this zone), there perimental management scheme was introduced was a steady decrease in the catch rates of between 1986 and 1991. This scheme consisted Lutjanus and Lethrinus species (Figure 3a) and of applying three differentmanagement regimes an associated decrease in the two sizes of on three large areas of the NWS (Figure 1). This epibenthic organisms (Figure 3b). management approach is 'actively adaptive' because it includes taking management actions These results show a good correlation be­ that intentionally try to increase the contrast tween the catch rate of the large commercial fish between control variables. This approach im­ species and the abundance of epibenthic organ­ proves identification of the key processes in the isms. However, this does not necessarily imply dynamics of the managed system. (A more an ecological association, as both the fish and complete description of the application of this epibenthic populations may be responding sepa­ approach to the NWS is given in Sainsbury rately to the effectsof trawling. To test forthis 1991). possibility, the likelihoods of observing the ex­ perimental results described above under alter­ CSIRO Division of Fisheries monitored: native models of the resource dynamics were 1) how the various fish species responded to calculated. Three of these models included a the changed fishing regimes; response by the fish populations based on changes in interspecific and intraspecific processes alone 2) the recovery rate of habitats after trawling while a fourthalternative assumes that thernrry­ ceased; and ing capacity of all groups of fish species is 3) the effect of trawling on habitats. determined by the amount of suitable habitat,

Bureau of Resource Sciences Proceedings 141 and habitat abundance is altered by the effectsof that rolled under the net and so would not be trawling (for a full description of the models and caught and seen by ship-board observers. From necessary steps in calculating the likelihoods the video observations only 10% of the dam­ refer to Sainsbury 1991). Combining the his­ aged organisms were seen to be thrown up and torical catch and effort information with the into the net. Hence it would appear that the research data collected on the NWS since 1982, amount of benthos recovered in a trawl net is the most likely model of the resource dynamics only a small component of the benthos that is is that in which the abundance of the major fish damaged by the trawl ground gear. Absence of groups is limited by the amount of suitable benthos in the recovered net does not necessar­ habitat available. ily imply that none was damaged While the effectsof trawling on epibenthic habitats may be inferred from the continued decline in such habitats in the areas trawled (and Discussion the recovery in the areas closed to trawling), The analysis carried out on the North West Shelf direct video observations were made of the has proved very useful in guiding management passage of the trawl gear over the sea bed. A actions despite the initial levels of uncertainty. video 8 camera was placed in an underwater Results to date indicate that the composition of housing and attached to the headline of the trawl the multispecies fish community on the NWS gear. The camera was positioned so that it looked (and possibly other tropical areas of Northern down and back towards the footrope. The field Australia) is at least partially habitat dependent of view encompassed the ground gear and an and that historical changes in relative abun­ area of around 3 to 4 metres both in front and dance and species composition in this region are behind. at least in part a result of the damage inflicted on The results of those video observations are the epibenthic habitat by the demersal trawling given in Table 1 (a complete description and gear. Furthermore, continued alteration of the analysis of the observations will be published demersal habitat due to trawling will probably elsewhere). The fate of epibenthic organisms continue to alter the species composition with after impact with the trawl gear remained un­ increasingly adverse effects on catches of known in over half (52%) of the 393 observa­ Lutjanus andLethrinus species. Recovery of the tions. Where the fate on impact was known large epibenthic organisms in the areas which ( 188) epibenthic organisms remained intact in have been closed to trawling appears to be slow. only 10% of the cases, with damage (detach­ There appears to be considerable sccpe for ment from the sea-bed) occurring in the other using the 'adaptive' management approach in 90% of observations. Bounds on the probability fisheries research to provide active feed-back of damage on impact with trawl gear can be between management action and empirical learn­ calculated by making extreme assumptions about ing. New management measures can and should the observations when the fate was unknown. If be introduced in ways that provide information all observations where the fate is unknown are which will guide the choice of long-term man­ included in the undamaged category then the agement actions. Such approaches can be ex­ probability of damage due to the passage of the pected to enhance management for sustainable trawl is 0.43, whereas if all unknown outcomes resource use. are considered to have resulted in damage then the probability of damage is 0.95. Of particular interest in assessing the effect of trawls on the epibenthos is the proportion of damaged items which are caught in the net compared to those

142 Bureau of Resource Sciences Proceedings References Bellamy, Dr. (1842). Guide to the fishmarket. Quoted in Street, P. (1961) pp. 34-35 In Vanishing Animals. Preserving nature's rarities. Faber and Faber, Great Britian, 232 pp. Cushing, D.H. (1980). The decline of the herring and the gadoid outburst. J. Cons. fill. Exp/or. Mer 39, 70-81.

Hempel, G. (1978). North Sea Fisheries and fish stocks - a review of recent changes. Rapp. Proces-Verb. Rew1. Cons. /111. Exp/or. Mer 173, 145-167.

Liu, H. C. and H. L. Lai (1980). Cost-revenue analysis of Taiwanese pair trawlers operating in Australian wa­ ters. Acta Oceanogr. Taiwanica 8, 109-140.

Moran, M., J. Jenke, C. Burton and D. Clark (1988). The WesternAustralian trap and line fishery on the North West Shelf. FIRTA Report 86/28. W.A. Marine Re­ search Laboratories, 79 pp. Sainsbury, K.J. (1982). The biological management of Australia's multispecies tropical demersal fisheries: a review of problems and some approaches. CS/RO Marine Laboratory Report 147, 16pp. Sainsbury, K.J. (1987). Assessment and management of the demersal fishery on the continental shelf of north west­ ernAustralia. pp. 465-503 In Tropical snappers and groupers: biology and fisheries 111a11age111elll. Ed. by J. J. Polovina and S. Ralston. Westview Press, Boul­ der, CO.

Sainsbury, K.J. (1988). The ecological basis of multispecies fisheries, and management of a demersal fishery in tropical Australia. pp. 349-382 In Fish population dynamics (2nd ed.). Ed. by J. A. Gulland. John Wiley and Sons, Chichester and New York.

Sainsbury, K. J. (1991). Application of an experimental approach to management of a tropical multispecies fishery with highly uncertain dynamics. ICES mar. Sci. Symp. 193, 301-320.

Walters, C.J. (1986). Adaptive 111anage111ent of renewable resources. Macmillan Press, New York. Walters, C.J. and R. Hilborn (1976). Adaptive control of fishing systems. J. Fish. Res. Board Can. 33, 145- 159. Walters, C.J. and R. Hilborn (1978). Ecological optimiza­ tion and adaptive management. Ann. Rev. Ecol. Syst. 9, 157-188.

Bureau of Resource Sciences Proceedings 143 area closed to trawling Oct. 1987

w .

21°S

w\J

Figure 1. The area on the North West Shelf in which the CSIRO research was conducted. The zoning used during the experimental management between 1986 and 1991 is also shown.

80 1.0 0,9 70 0,8 60 i:: 0. 7 0 50 ,,l 0,6 1-1 o.s f ..c: 40 0 o., 30 1-1 u 0,3

20 0.2 --r! 10 0,1 -I ---1-I --de-I -I 0 0,0 85 86 87 88 89 90 91 86 87 88 89 90 91 Year Year Figure 2a. Total catch rate of lethrinus andl11tja1111s Figure 2b. Proportion of sea-bed with large (closed (kg/30 min) in the zone closed to trawling in October square) and small (open circle) benthos in the zone 1985 based on the annual research data. Standard closed to trawling in October 1985 based on the errors and line of best fit are also shown. annual research data. Standard errors and line of best fit are also shown.

144 Bureau of Resource Sciences Proceedings 120 Table 1. Effects of demersal trawling on marine epibenthos 100 Observed effectsdue to the passage of the trawl 4) 80 ground gear on epibenthic items larger than the width of the ground gear itself (about 15 cm). These data are based on video observations taken .d 60 of seven 30 minute demersal trawls. u 40 Type ofobservation Number Percent 20 l f ' ! i No observed effect 19 5 Broken and rolled under net 154 39 8 6 87 88 89 90 91 Year Broken and caught in net 15 4 Figure 3a. Total catchrateofLethrinus andLutjanus Unknown 205 52 (kg/30 min) in the zone left open to trawling based on the annual research data. Standard errors and lines of Total observations 393 100 best fit are also shown.

1.0

0.9

0.8

0.7

0.6 o.s

0.4

0.3

0.2

0.1

o.o 86 87 88 89 90 91 Year Figure 3b. Proportion of sea-bed with large (closed square) and small (open circle) benthos in the zone left open to trawling based on the annual research data. Standard errors and lines of best fit are also shown.

Bureau of Resource Sciences Proceedings 145 DISCUSSION OF SESSION 5

Recorded by P.C. Coutin MarineScience Laboratories P.O. Box 114 Queenscliff VIC 3225

The presentation of each paper by individual Phil Cadwallader cited the Fish panellists was followed by brief questions and Management Plan of the Murray-Darling discussion, which are reported here together Commission as a good example of the direction with the concluding general discussion which for freshwater fisheries management which was led by the Session Chairperson. involves fish habitat restoration programmes utilising techniques such as fish ladders. Following Martin Mallen-Cooper's panel However, he pointed out that an essential presentation on changes in the distribution and element was the associated television abundance of freshwater fish due to changes in advertisements produced by the Commission's habitat, Stan Moberly suggested to the Society educational unit which increased public that a vision of the future of fish habitats is awareness of freshwater habitat issues. needed. By using the Society's collective wis­ dom, it should be possible to predict what the Given sufficientresources, Martin Mallen­ human impact on fish habitats would be in the Cooper agreed that even a small group of future. Before such an impact occurs, these people could change public opinion at grass predictions should be communicated to the de­ roots level and suggested that as an outcome of cision makers. the workshop, the Society should recognise the Martin Mallen-Cooper responded that the importance of public education. Society could already list the human impacts John Koehn opened the discussion on that have the greatest impact on freshwater fish Greg Jenkin' s presentation by commenting habitats and proposed that such a list should be that the 70% loss of seagrass and the subse­ compiled during the workshop. It was suggested quent decline in commercial fin fish catches­ that the Society should be more proactive in particularly of King George whiting-in promoting fish habitat issues and that scientists Western Port Bay was a classic case of lack of should communicate their existing knowledge. management foresight and lack of publicity Referring to water quality and fish move­ about habitat degradation. The loss of seagrass ments, Peter Gehrke stated that a great deal was could have been predicted a long time ago if the already known about freshwater fish habitats, effects of draining the swampland around and significant advances have been made to add WesternPort Bay had been thoroughly consid­ to this knowledge. He proposed that scientists ered. The subsequent scouring of river beds in should capitalise on this knowledge to prevent the catchments led to massive amounts of further habitat degradation and to actively pro­ sediments entering Western Port Bay which mote habitat enhancement. For example, smothered the seagrass beds and elevated the fishways should be constructed to allow fish to mud banks. Until a few years ago, neither move upstream above dams and weirs. coastal nor catchment managers had recog-

146 Bureau of Resource Sciences Proceedings nised the problem. Urgent management action whether the direct fishing mortality caused by was required to avert the threat of sedimenta­ Taiwanese pair trawlers, which involved tens of tion from poor land practices in order to main­ millions of lutjanids and lethrinids, had made a tain the current quality and quantity of bigger impact on the fish community than the freshwater and estuarine fish habitats. Costly indirect effect of trawl nets through damage to habitat restoration programs were required to the seabed. retrieve aquatic environments froma history of Robert Campbell replied that a number of poor land use practices and to allow the quality models and assumptions had been tested by his and quantity of fish habitats to fully recover. co-investigator Keith Sainsbury and that the George Paris reiterated the importance of direct impact of fishing mortality on the compo­ education and publicity about habitat loss. Re­ sition of the fish community was less than the ferring to the proposed re-location of the Coode indirect impact of habitat degradation. The Island petro-chemical complex to Point Wilson models indicated that the habitat-driven re­ in Port Phillip Bay, Victoria, he suggested that sponse was the most likely factor to have caused even poor or misleading information on envi­ the change in the fish populations. Although the ronmental impacts was better than no informa­ recovery of habitat after trawling had ceased tion in helping to produce the right social and appeared to be quite good, it was a slow process environmental outcome. The current lack of and full recovery of the habitat following heavy public advice from marine biologists would trawling may take up to twenty years. achieve nothing at all. He proposed that the Given the effects of trawling on the habi­ Society should follow the example of the Royal tats and fish communities of the Northwest Australian Ornithological Union by releasing shelf, Russell Reichelt asked whether a similar press statements and providing advice on the effect on habitat and fish communities may impacts on the aquatic environment, fish habi­ have occurred in the South East Trawl Fishery. tats and fisheries, of threatening human activi­ He observed that a map of all the trawl shots ties such as the development of the proposed made over the last five years showed that there new site of the petro-chemical complex in had been a complete coverage over the shelf in Victoria. south eastern Australia. He suggested that the Greg Jenkins, however, stressed the need fish stocks present today represented a 50-100 for scientists to state the facts correctly and year shift in population structures that is now criticised some environmental lobby groups being maintained by the effects of trawling on that made factually incorrect press statements the fish habitat and the fish stocks. which misled the public. It would be far better Robert Campbell commented that there for responsible scientific organisations, such had been very heavy trawling on the Northwest as the Society, to release accurate statements at shelf and the data indicated a complete cover­ an early stage. Once the wrong facts have been age by trawlers during the 1970s. While fisher­ given to the public, it is very difficult to make ies management is based on a concept of the corrections in the press. Good scientific advice original fishery there are rarely any supporting to the media would be really worthwhile. data to indicate the composition of the initial Julian Pepperell opened discussion on habitat and fish communities. Robert Campbell's account of the effects of Murray MacDonald opened the general trawling on marine communities on the North­ discussion by repeating the objectives ·0f west Shelf of Australia by noting that the Session 5: change in the quality and quantity of habitat on the Northwest shelf has caused changes in fish to identify the categories of human impacts species composition. He asked the panelist on aquatic habitats;

Bureau of Resource Sciences Proceedings 147 to assess the scientific evidence for link­ Salinisation (land practices) ages between human activities, habitats Contaminants (organic and inorganic) and fisheries resources; and Introduction of non-native species • to identify strategies for demonstrating to (including translocations) the public and decision makers the link between human impacts and the degrada­ Estuarine Habitats tion of aquatic habitats. Habitat loss (eg. shoreline development, dredging, drainage schemes) He suggested that the Society could take a leading role in identifying the full range of Changes in salinity ( eg. altered river flows, human impacts on aquatic habitats and in as­ artificial openings to the sea) sessing the quantity and quality of scientific Eutrophication (fertilisers, sewage) evidence for the linkages between human dis­ turbances of aquatic habitats and the subsequent Sediment deposition (land use practices) effect on fish communities. When these tasks Impact of fishing methods have been completed, the Society and indi­ vidual scientists could then provide guidelines Contaminants (eg. heavy metals and and recommendations on the management of hydrocarbons) human impacts on fish habitats to decision mak­ Introduction/translocation of exotic species ers. (eg. oriental goby, toxic algae) The Society could also package the existing Marine Habitats habitat impact information in a formsuitable for Impact of fishing methods on the seabed a broader audience of managers, legislators, and benthic community (trawling/dredging) politicians and the general public. Convincing the public of the need for fish habitat protection Hydrocarbons (oil contamination) and aquatic conservation and providing scien­ Waste and debris (eg. ocean dumping) tific information in a suitable formwould help to create a climate which would allow politi­ Effluent disposal cians to make informed decisions about the Global Effects on Fish Habitats alternative management objectives and actions Climate change / the Greenhouse effect that are available to them. He also suggested that the Society could identify the additional infor­ Changes in sea level / rainfall mation needed by scientists, managers and the Ozone depletion public to show more clearly the effects of vari­ ous human activities on aquatic habitats and Referring back to the Habitat Conservation thereforefish populations. Program of the US National Marine Fisheries Service, Murray MacDonald outlined the threats A number of categories of human impacts to living marine resources and habitats that had on aquatic habitats were listed been identified and ranked on a regional and Freshwater Habitats national basis in the USA. Both managers and Habitat loss (dams, flow regulation, scientists had developed strategies to address channelisation) these major habitat threats, had prioritised the implementation of those strategies within the Eutrophication (land practices, fertilisers, constraints of existing resources, and had also sewage) sought additional resources. Key information Sediment deposition (land practices, required to determine each human impact on forestry) fish habitats has been identified and research

148 Bureau of Resource Sciences Proceedings tasks to address specific information require­ using television advertisements to ensure that ments are undertaken in priority order. Informa­ there was a high level of understanding and tion so obtained is used by governmentagencies acceptance. Land care programmes such as re­ to guide and control the human activities which afforestation and re-vegetation have also been have a major impact on fish habitats. Murray well supported due to effective publicity cam­ MacDonald suggested that perhaps Govern­ paigns which have been developed as part of a ment agencies in Australia could adopt a similar national resource management strategy. How­ approach. ever, he agreed with Stan Moberly that the most Stan Moberly cautioned that in spite of the important requirement in addressing habitat progress that had been made there was still a degradation and loss is money. There is a need major requirement in the USA for more money to convince the public of the seriousness of to address fish habitat issues. The National Fish these issues, and scientists should adopt more of and Wildlife Foundation had recently recom­ an educational or extension role, like writing mended to the US governmentthat in addition to popular articles and using television to get the the $8 million in the NMFS 's habitat budget, an message across. It is necessary to get away from additional $12 million dollars should be pro­ the ivory tower mentality and fromclosed aca­ vided to make a total of $20 million. However, demic circles. If scientists leave the job of com­ the House of Representatives voted not to in­ municating habitat issues to media journalistsor crease the level of funding to address fish habitat to public relations officers in Government de­ issues, and the Senate voted to increase funding partments, the message will invariably be wrong. by only $2 million. When the House and the The facts really need to be told by scientists. Senate conferred on this matter they finally Martin Mallen-Cooper agreed that communica­ voted to allocate no extra funds at all. So no tion and community education need to be given matter what strategy is developed, and no matter priority by the Society and that the necessary how much research on the impacts of human funds need to be obtained. activities on fish habitats is done, it achieves Rob Lewis identified the need to communi­ nothing until the Governmentgives the issue a cate clear and simple messages to the public, high priority and allocates sufficient funds to and cited as an example the successful national tackle the problems of habitat degradation and publicity campaign to reduce littering. He loss. Increasing numbers of people in the USA claimed that people litter far less today because are becoming aware of habitat issues, but funds of the successful poster campaign and a short, are not being made available to address these simple television campaign-not because sci­ issues. entists put forward piles of detailed environ­ Murray MacDonald asked how the Society mental impact assessments into the public could convey the habitat message in Australia in domain. With simple messages, children and a manner that would convince politicians to give adults could be convinced not to cause a littering habitat issues a high priority. Mick Olsen won­ problem. He suggested that the Society should dered whether the Society could support already consider a poster campaign on the fish habitat existing public education programmes like that issue, with short snappy phrases that will influ­ of the Murray Darling Basin Commission. ence people over a period of time, rather than offering detailed scientific advice which most Phil Cadwallader agreed that the Murray­ people are not going to accept or even under­ Darling Basin Commission had recognised some stand. of the key factors that caused habitat degrada­ tion and had developed a management plan to Murray MacDonald agreed that it was vital tackle habitat issues. More importantly, the to pitch the message at the right level depending management plan had been "sold" to the public on the audience. He asked for comments on the

Bureau of Resource Sciences Proceedings 149 role of scientists in providing simple environ­ known as "The environmental studies revolving mental messages for public awareness cam­ fund" (ESRF). All the oil companies put in a paigns, and on whether scientists actually need small percentage of their profits,thus generating to collect detailed scientific information for millions of research dollars. A committee such purposes. Rob Lewis reiterated that pub­ consisting of Government and oil industry licity campaigns needed to be consistent, sim­ representatives was set up to administer the ple and widespread, but stressed that it was vital tendering for all oil exploration projects requiring that scientific research should continue to be Environmental Impact Statements. The ESRF conducted to provide an authoritative factual funds were thus used to collect scientific basis for the message to the public. infmmation which could be accessed by the entire oil industry. This approach solved the Margaret Shepherd added that a financial fundingproblem as it basically made use of the incentive, such as fines or an environmental 'user pays' system - a concept which may be levy, was a very effective way of rapidly bring­ applied to aquaculture and othernatural resource­ ing environmental issues to public attention. based industries. Using the example of the environmental levy imposed on water rates in NSW, she pointed out Peter Jackson agreed that the Society had to that the public was very quick to demand action act now and that it could not wait for more when rubbish from the deepwater sewage research results. The Society could already list outfalls appeared on Cronulla beach. The pub­ the threats to Australian freshwater habitats at lic had refused to pay the rates until the beaches least and, more importantly, could identify some were cleaned. She suggested that an environ­ of the broad strategies required to deal with mental levy was a good way to raise public those threats. These strategies should be com­ awareness and to obtain funds for research. Rob municated to politicians and managers as quickly Lewis agreed that the public will want value for as possible. In Queensland the state Govern­ money if Governments decide to apply an envi­ ment is frequently being asked how to protect ronmental levy. However, the community will freshwater habitat, and scientists should pro­ not demand an environmental levy without a vide up-to-date information in response to such proper marketing program which promotes requests. However, it is important to recognise habitat issues and convinces them of the need that gaps in our knowledge of human impacts on for a levy. freshwater fish habitats still exist. Peter Jackson proposed that the Society should identify those Bob O'Boyle returned to the problem of gaps and put forward a research strategy to funding habitat research and gave a Canadian collect the missing info1mation. example of raising research funds from offshore oil exploration that developed in the 1970s. Jim Puckridge believed that it is the Initially, the Governmentof Canada established Society's responsibility to communicate very strict guidelines in relation to the available information on the impacts of human Environmental Impact Statements (EIS) for activities on fish habitats. He suggested that at a offshore oil exploration which involved future Society workshop a session should be individual companies funding large scale devoted to explaining how scientists can more ichthyoplankton surveys, full scale demersal effectively communicate with the media, attract fish surveys, and oceanography. However all media attention, and provide a coherent and the data that were generated by those surveys effective message. David Smith identified two were confidential, and all the other oil companies types of information that scientists should had to repeat the surveys if they wanted to provide. The first type was detailed scientific obtain their own information. Consequently, advice which identified key issues and options the oil industry established a national fund, for policy makers and set priorities for research.

150 Bureau of Resource Sciences Proceedings The second type of information was the short, seagrass beds, usually represent the combined simple message to the public through the media activities and/or requirements of many people or a poster campaign such as "Fishers Involved in the private and public sectors of the commu­ in Saving Habitat". nity, and their environmental impacts cannot be attributed directly to specific individuals. Referring to the demand fora ban on com­ mercial scallop dredging in Port Phillip Bay, John Glaister noted that there are quite a Peter Young cautioned against providing ad­ fewState and Federal governmentagencies and vice in the absence of supporting scientific non-government organisationsthat are already information. He stated that, unlike the apparent providing considerable resources forpublic edu­ situation for freshwaterhabitats, relatively little cation on fish habitats. For example, Ocean was known about the impacts of human activi­ Watch, the Queensland Commercial Fisher­ ties on fish habitats in marine and estuarine men's Organisation and Queensland Fisheries environments. Russell Reichelt re-emphasised have all conducted public awareness programs the need for solid scientific information to back on fish habitat issues. He suggested that the up the simple messages of a publicity campaign. Society should coordinate a national campaign He expressed concernedat the apparent lack of and capitalise on these efforts. He proposed that compiled information that showed the total loss the Society should establish a Threatened Habi­ or degradation of aquatic habitats on a national tat Group, consisting of key people fromState or statewide basis due to human activities such and Federal organisations, to collate informa­ as canal estate development, swamp drainage tion on the status of aquatic habitats. Murray schemes, and pollution of estuaries, mangroves MacDonald added that to carry out these tasks and seagrass beds. This broad scale information more quickly and efficiently it could be appro­ was needed to convey the seriousness of the priate to combine the resources of the Society habitat issue to the media and the public. with other professional societies like the Aus­ tralian Marine Sciences Association and the Julian Pepperell, as President of the Soci­ Australian Society for Limnology. ety, considered that it was well within the scope of the Society's charter to put together some Stan Moberly stressed that the Society good graphic material for the media and general should focus on transferringthe knowledge that public that showed the loss and degradation of we have already in simple and straightfoward aquatic habitat in Australia. He proposed that terms. If there are unanswered questions, these scientists in the Society with good computer should be used to identify and focus research graphic skills could produce, for example, maps needed. However, this need for further research showing the decline in seagrass beds and man­ should not be the main message scientists send grove stands around the entire Australian coast­ to the public. We need to convey to the public line. Once the material is compiled, the next what we already know so that this information problem is to broadcast the message to the can be used to help make decisions the commu­ general public. However, attracting the media's nity faces now. For example, it is not worth attention on such issues is difficult. Television arguing to the public exactly how bad sewage is is the best way of conveying the message to a for fish habitats; the public just needs to know wider audience, but this would require Govern­ that it is bad and does not improve fish habitats. ment funds. Another problem is that many indi­ When someone asks "Just how bad is the sew­ viduals do not perceive any obvious personal age?" , we should convey the message that "it responsibility forenvironmental impacts on fish doesn't taste very good and its not good for habitats. Projects such as construction of dams, fish!". Another example is the reduction of river de-forestation, sewage disposal, and land use flows through water abstraction or storage in practices which cause the gradual siltation of dams. The public doesn't need to hear our scien-

Bureau of Resource Sciences Proceedings 151 tificdebates over how much water flowneeds to be maintained, but rather they need to know that if we expect fishto migrate upstream and pass through fishways around dam walls, there has to be sufficient water flow to accommodate that movement. Simple messages are required for the public, such as "Dumping dredge spoil over seagrass beds does not improve fish habitats". "Fish need water to migrate upstream". "If you want seafood to taste good, don't dump sewage in the water". "If you want to swim on nice beaches don't dump sewage in the water". These are the kind of messages that raise public awareness and consequently raise the profile of fish habitat, water quality and water quantity issues. It should be a simple process to apply the successful media campaign on litter­ ing to a simple message on fish habitat conser­ vation. In the USA the campaign on marine debris swept the nation as a result of an aquatic education programme which pointed out the problem and suggested solutions, but didn't get into a debate about how much marine debris is bad. The same approach could be taken in Australia. MurrayMacDonald concluded the discus­ sion and urged the membership and the execu­ tive of the Society to implement the ideas that had been put forward.

152 Bureau of Resource Sciences Proceedings SESSION 6

ALTERNATIVE USES (ECONOMIC, SOCIAL AND POLITICAL)­ KEY VALUES

Session Chairperson: R. Reichelt Session Panellists: D.A. Pollard A.J. Staniford Rapporteur: J. Robertson 154 Bureau of Resource Sciences Proceedings CHAIRPERSON'S INTRODUCTION

R. E. Reichelt Bureau of Rural Resources GPOBox858 Canberra ACT 2601

Use of a habitat means different things to Analysts often maintain different world different "users". In some countries there are views. Economists sometimes regard the uni­ those for whom a shallow coastal coral reef is verse as an economic system within which ecol­ of more use as a landing site for a heavy military ogy is one component, many others regard vehicle. In Australia the same reef might be economics as one component of our ecosystem, regarded as an ideal site to dredge a stable and a third group regard economics and ecology speedboat harbour or build a canal estate. There as separate dimensions within our human niche. would be others who would consider the best From a fish biologist's standpoint the large use of the reef to leave it as it is. problems are: The Australian public (and media) are defining the environmental impact caused becoming increasingly aware of the importance by, or likely to be caused by, an alternative of our inland waterways and "Injured use; Coastline". However, both fisheries scientists and the public are still desperately short of hard recommending options for controlling the information about the role of particular habitats degree of the impact ( or effect); in sustaining both fish populations and other developing precise and comprehensible (not living resources. For example, an interviewer necessarily quantitative) assessments of the recently asked me whether the destruction of risks associated with alternative uses. any particular mangrove stand near Coffs Harbour could explain the disappearance of Outside the usual brief for fish biologists lie younger age classes of gemfish from the winter the realms of bioeconomic risk assessment, re­ spawning run. source pricing and establishing the full range of alternativereasons that people may want to use When conflicts between users of a common fish habitats. Yet the community expects fish resource occur in Australia they are handled in biologists to provide a sound input to analyses in various ways, including publicity campaigns, these other areas. Resource Assessment Commission Inquiries, legal challenges and civil disobedience. All too Fish biologists should aim to have an effec­ often the conflicts are treated with confusion, tive input to both the policy making process and apathy and political procrastination. Although the use of scientific results in decision making the complex jurisdictional arrangements can concerned with regulating the use of fish habi­ exacerbate the situation, biologists are tats by a broad spectrum of users. Our panel frequently unable to provide the information speakers will spark debate on these broad issues called for by resource economists in evaluating and the approaches that fish biologists could particular conflicts. take to achieve this aim.

Bureau of Resource Sciences Proceedings 155 MAXIMISING THE POTENTIAL FOR BOTH SUSTAINABLE FISHERIES AND ALTERNATIVE USES OF FISH HABITAT THROUGH MARINE HARVEST REFUGIA

D.A. Pollard FisheriesResearch Institute P.O. Box 21 Cronul/a NSW 2230

The main aim of this session of the Workshop, development as being legitimate "uses" in this as I interpret it, is to stimulate and provoke context. The sort of acceptable alternativenon­ discussion on the management of"fish habitat" consumptive uses to which I will be referring in relation to maximising the compatibility of could be broadly grouped as recreational, edu­ alternative non-consumptive uses with the con­ cational, scientific and aesthetic-the demands sumptive uses of fisheries resource harvest. for all of which might be expected to increase with increasing affluence,leisure time and tour­ As the term "fish habitat" is a very broad ism in the not too distant future. one, and could include most aquatic ecosys­ tems, in introducing this discussion I will con­ What I would like to do to stimulate discus­ centrate mainly on the marine/estuarine system. sion is to consider a future scenario in which Although the problems of management of fresh­ demands for these alternative uses, and also the water/inland aquatic systems are in many ways demand for fisheries products, have greatly in­ both qualitatively and quantitatively different, creased, and to consider an appropriate manage­ any discussion from the floor of the applicabil­ ment regime to address the inevitable ecological ity of what I have to say in relation to freshwater pressures and use-conflicts which will arise. ecosystems would also be most welcome. The marine/estuarine system has, of course, I don't intend to go into the details of the traditionally been regarded as a"commons" (but relative importances of different types of fish see footnote below*), and until relatively re­ habitats, which are disc11ssed in other sessions cently a generally open slather approach to its of the workshop, though such shallow water usage has been dominant and almost universal. inshore marine and estuarine nursery habitats as Needless to say, this "let her rip" laissez faire seagrass meadows, mangrove swamps, and approach cannot be allowed to continue, and rocky and coral reefs could be kept in mind because of their ecological importance and vul­ * "Despite widespread usage of the term 'commons', our current institutional structure forocean management does nerability. Neither do I intend to go into the not meet one critical criterion for common property: details of the many and varied alternative hu­ community control. The tragedy of the ocean is not the man uses of aquatic ecosystems, though I would tragedy of the commons, but the tragedy of overuse. Overuse may result fromfragmented and ineffective own­ like to emphasise that we should not regard the ership. Overuse may also result from short-term profit destruction of fish habitat through such activi­ taking by private owners. It is a red herring to link overuse ties as dredging and reclamation for foreshore to common ownership" (Hanna 1990).

156 Bureau of Resource Sciences Proceedings viewing the system from a multiple-use per­ Over the many years we have all spent spective, the compatibility and conflicts of the seeking the details of whether and why juvenile many different potential uses urgently need to banana or tiger prawns preferred seagrasses or be considered in terms of both ecological mangroves, or whether and why juvenile sustainability and user equity. blackfish or leatherjackets preferred Zostera or Posidonia, vast areas of these valuable fish In this regard we need to consider the most habitats have been degraded and destroyed. appropriate management regime to achieve these Now, I'm not suggesting that we stop carrying basic aims of sustainability and equity. out this type of detailed ecological research, but Overall, I would consider that the mainte­ we certainly shouldn't wait to do something nance of ecosystem biodiversity, in terms of practical until we've found out all the answers. both the sustainability of the fish (i.e. the stocks After nearly 30 years in this field, to me, of renewable, and thus potentially harvestable, two things have become increasingly obvious: resources) and the preservation of their habitats the firstis that we are never going to understand (i.e. both the biotic and non-biotic components very much about how aquatic ecosystems really of their environments), should be the most criti­ work (e.g. exactly why do those baby banana or cal and primary management objective. While it tiger prawns prefer seagrasses or mangroves?); obviously needs to be considered concurrently and the second is that, in the longer term, we are with the above, effective management for eq­ not going to improve much on, or be able to uity of use allocation amongst the many differ­ replace, Nature's fine work in creating the fish ent competing user groups can only really be habitats that we already have. achieved once the maintenance of biodiversity has been seriously addressed. The natural habitat we see around us-for fish and everything else-is about as good as At present, the management of "fish" and it's ever going to get. For the continued mainte­ their habitats in most areas of the marine/estua­ nance of wild stocks, there is really only one rine system involves the piecemeal manage­ obvious and immediate thing to do, and that is to ment (sometimes successful, but often not) of preserve as much as possible of that which individual species, stocks, habitats and uses, remains in its natural state, while we still have carried out by a plethora of different and often the chance. If we do so, we can continue harvest­ competing management authorities, each often ing part of its productivity forour own purposes working within its own narrow and conflicting in perpetuity. legislative and jurisdictional framework.While this is obviously an improvement over the pre­ There is thus not such an urgent need to vious practically unmanaged state, in my view understand the details of exactly how "fish this approach cannot hope to assure the mainte­ habitat" works-that it does work has already nance of biodiversity, and thus equity of use, in been taken care of for us. To reiterate, what is the longer term. What I therefore suggest is most urgent is to preserve as much of it as needed is a much more holistic approach to possible in its natural intact state. Thus, maybe aquatic ecosystem management. one of our most vital tasks as an informed scientific Society should be to preach this mes­ In listening to the papers presented and the sage much more strongly out there in the com­ subsequent discussion over the past day and a munity in general-not only to the fishermen, half of this Workshop, I have started to get the engineers, planners, policy makers, etc., but impression that, on this habitat issue in general, also to the committed (though sometimes unin­ maybe most of us have been, like Nero, fiddling formed) 'greenies', the school kids, and all the (in our case with our nets and our computers) rest. while Rome burns.

Bureau of Resource Sciences Proceedings 157 In providing some food forserious thought Davis, G.E. (1981). On the role of underwater parks and then, I'll be provocative and suggest that the sanctuaries in the management of coastal resources in the south-eastern United States. Environmental Con­ only long term solution may lie in the total servation. 8, 67-70. protection from consumptive uses of very large areas of the marine and estuarine environment. Davis, G.E. (1989). Designated Harvest Refugia: the next stage of marine fishery management in California. The establishment of such extensive "marine CalCOFI Rep. No. 30, 53-58. habitat refugia", coupled with the use where necessary of more conventional but less holis­ Hanna, S.S. (1990). The Eighteenth Century English Com­ mons: a Model for Ocean Management. Ocean and tic management measures in the surrounding Shoreline Management 14, 155-172. fished areas, would help to replenish the fishable stocks in these areas through protection of both Roberts, C.M. and V.C. Polunin (1991). Are marine re­ adult spawning stocks and juveniles in their serves effective in management of reef fisheries? Reviews in Fish Biology and Fisheries 1 ( 1 ), 65-91. nursery habitats. Apart from providing con­ tinuous recruitment ofharvestable resources to fished areas, such marine habitat refugia would also thus be available for those alternative and relatively non-consumptive recreational, edu­ cational, scientific and aesthetic uses mentioned earlier, with existing conflicts between the two being greatly reduced. Although it only affects the waters adja­ cent to one State, the Great Barrier Reef Marine Park provides a model which demonstrates that a multiple-use management approach based on the general principles of ecological sustainability and user equity can successfully operate within a suitable framework of Commonwealth/State co-operation. I suggest, however, that with in­ creased usage the declaration of much larger areas of totally protected habitat as marine harvest refugia will be necessary in order to maintain biodiversity in the longer term, in not only the waters of the Great Barrier Reef but of Australia in general. Details of how such refugia may work, and assessments of their effectiveness,may be found in the references which follow.

References (not cited in text) Bohnsack, J .A. (1990). The Potential of Marine Fishery Reserves for Reef Fish Management in the U.S. Southern Atlantic. NOAA Technical Memorandum NMFS-SEFC-261, Miami, 40 pp.

158 Bureau of Resource Sciences Proceedings ALTERNATIVE USES OF AQUATIC HABITATS: AN ECONOMIC PERSPECTIVE

A.J. Staniford Office of Energy Planning 30 Wakefield St Adelaide SA 5000

Abstract the resource have led to overexploition and permanent resource depletion of one or more of Alternative uses of aquatic habitats are classi­ the organisms living in the habitat. In order to fied according to human participation and re­ prevent overexploitation, the various uses of the source depletion. The classification assists to habitat must be managed to ensure that the clarify the impact of human activity on the associated impacts are sustainable. resource. Each use places a demand on the habitat that may be compatible with other uses In this paper, I provide an economic per­ or mutually exclusive. The key question from a spective to the alternative uses of aquatic habi­ management viewpoint is how to meet these tats. The te1m habitat is interpreted in its broadest alternativedemands. sense to be a region of space where living organisms interact. Alternativeuses of habitats Three options are discussed; the market are categorised into three groups and alternative approach, the regulatory approach and the value­ management approaches are contrasted. added approach. It is demonstrated that the value-added approach is the preferred option. The capital value of the habitat is explicitly recognised with this approach. It provides a Alternative uses of aquatic habitats strong basis for developing strategic, forward­ Aquatic habitats are used for a variety of pur­ looking, consultative management programs that poses, ranging from providing leisure activities will effectively meet the alternative demands for society, to being used as a means to generate placed on the habitat. economic wealth (e.g. fishing). In this paper, I Aquatic habitat management in Australia is categorise alternative use of habitats into three moving towards a value-added approach. The groups (Table 1). rate of progress, however, needs to be acceler­ Category l is defined as actions that are ated. Actions required to progress this approach both participative and depletive. Participation are proposed. refers to activities in which there is direct inter­ action of human activity with the habitat. The level of depletion is defined as the extent to which human activity reduces the quality of the Introduction asset. Depletion may be temporary or perma­ Aquatic habitats provide a range of alternative nent. Category l includes commercial and rec­ uses to society with the potential to improve reational fishing. It also includes activities such welfare. However, there are many examples of as waste disposal and the use of aquatic habitats aquatic habitats where the demands placed on for commercial and industrial processes.

Bureau of Resource Sciences Proceedings 159 Category 2 is defined as part1c1pative Some of these demands are compatible non-depletive uses. In these, humans interact with other uses, while others are incompatible. directly with the habitat but do not deplete the The key objective of management is to ensure asset. Activities include commercial shipping, that the aquatic habitat is used efficiently, to recreational boating, surfing, swimming, meet where possible society's demands for the snorkelling, diving etc. and the use of habitat use of the habitat, taking into account the finite foraesthetic purposes. nature of the resource. If alternative demands cannot be met on a sustained basis, management Category 3 is defined as non-participative should ensure that the alternative uses are ra­ non-depletive uses. Even if individuals never tioned to maximise the contribution of the re­ visit or deplete a habitat, the fact that the source to the welfare of society. resource exists may in itself be beneficial (Kratilla and Fisher 197 5). Mitchell and Carson (1989) classify existence ( or non-use) benefits into two types - vicarious consumption and Management options stewardship. Vicarious consumption refers to Alternative management options available to benefits gained from knowing that others are allocate the services derived from an aquatic using the resource. In the case of an aquatic habitat to competing demands can be classified habitat, an individual may derive benefit from into three categories. knowing that members of his family, friends and the general public are able to use the habitat 1. The unregulated market approach to pursue activities, such as those listed in Economic theory demonstrates that the benefits Categories I and 2, that will improve their (social welfare) from using a resource will be utility. Stewardship values involve the desire to maximised when potential alternative uses are see a public resource used in a responsible allocated according to the equilibrium of a com­ manner and conserved for future generations. petitive market system (e.g. Gravelle and Rees For example, individuals may derive benefit 1981 ). In recent years, governments throughout from knowing they can pass on a specific the world have been increasingly using market aquatic habitat to the next generation even if mechanisms to achieve efficient use of natural they do not personally visit the site (bequest resources in the economy. value). Also individuals may consider that some habitats are intrinsically valuable to society and Markets exist for some of the products that should be preserved regardless of whether they originate from aquatic habitats (e.g. fish, tour­ will ever be used by anyone (inherent value). ism) and for some of the inputs required to enable people to derive benefit from the re­ Each alternative use identified in Table I source (e.g. recreational fishing and boat sup­ places a demand on the habitat. The nature of plies). One management option is to allow the demands arising from each use is also altemati ve uses of the resource to be determined indicated in the Table. Category I produces a according to the market outcome. demand for depletion (a reduction in the quality of the asset) and space (to enable human However, there is a large body of evidence interaction with the habitat). Because Category available demonstrating that the operation of an 2 is non-depletive, the demand created is only unregulated market in this context will not pro­ for space. Category 3 creates a demand for duce a socially efficient outcome. Aquatic habi­ sustainability; provided the resource is tats have common property (Gordon 1954) and sustained, the demand forCategory 3 uses can public good characteristics (Cornes and Sandler be met. 1986) that ensure that the market outcome will

160 Bureau of Resource Sciences Proceedings not be optimal. The failure of the market to Fishers respond to the regulations by substi­ produce an optimal outcome is referred to as tuting non-regulated inputs for those that are market failure (Tietenberg 1988). regulated. This action reduces the effectiveness with which the regulations protect the stock, 2. The regulatory approach implying that the severity of the regulations will eventually have to be increased to maintain the Intervention by the governmentis often advo­ resource at the desired level. More importantly, cated to correct situations of market failure input substitution by fishers increases the cost of (provided the cost of intervention does not ex­ harvesting the fish. Potential profits that could ceed the benefit). Intervention is usually achieved be earnedfrom the fishery are thus reduced. The through implementation of a regulatory ap­ reduction in profits reduces the economic contri­ proach. With a regulatory approach, govern­ bution of the fishery to society. ments recognise that the demands placed on habitats from alternative uses sometimes ex­ A further characteristic of the regulatory ceed the capacity at which they can be supplied approach is that regulations are typically intro­ on a sustainable basis. They therefore intervene duced after a problem becomes apparent. Thus, to introduce controls on either participation even if industry is consulted before implementa­ (e.g. limited entry) or depletion (e.g. bag limits tion of the regulations, the urgency of the prob­ or quotas) to prevent overexploitation. lem to be solved often produces political actions and conflict amongst participants. The regula­ Using the terminology of this session, the tions implemented are often a compromise and key value implicit in application of the regula­ oriented towards solving the current problem. tory approach is preservation of the habitat and interacting organisms. Regulations are devel­ oped and implemented and the effectiveness of 3. The value-added approach the regulations is assessed according to the A value-added approach recognises that aquatic degree of success in maintaining the habitat. habitat is a natural asset that has a capital value. The value of the asset is the sum of the benefits The regulatory management approach can derived by all current and future users of the be extremely effective at preventing resource. A value-added approach to manage­ overexploitation of individual species by re­ ment seeks to maximise the total value of the stricting the level of exploitation of the habitat. asset. However, it is characterised by two major defi­ ciencies: it is inflexible and inefficient. Once In contrast to the regulatory approach, the regulations are enacted, they are often difficult key value is the asset value, not the need to to alter quick! y should circumstances change. If preserve the resource. Due to the market failures a regulatory approach is to be used, effortshould associated with aquatic habitats, a value-added be directed to ensuring that the regulations en­ approach will include regulations. This may acted are as flexible as possible to enable man­ involve input controls and/or output controls. agers to respond to unforseen perturbations of However, the focus of the regulations will be the aquatic habitat. fundamentally different from the regulatory ap­ proach. With the value-added approach, empha­ Even if regulations are flexible, a regula­ sis is redirected frompreventing overexploitation tory approach will encourage users of the habi­ or protecting the resource, to looking for ways to tat to pursue strategies that minimise the adverse improve value. impact of the regulations on their activities. This Asset value could be improved by: effect is clearly demonstrated through analyses of the impact of regulations on fishing effortin varying the level of exploitation of the commercial fisheries e.g. Anderson (1985). habitat (e.g. reducing fishing effort);

Bureau of Resource Sciences Proceedings 161 changing access rules to alter the the way in agers need to search for innovative meth­ which the resource is allocated between ods to increase value through changing existing participants; and current use patterns. encouraging new uses that develop the 2. More research effort needs to be directed habitat. towards determining current and potential values of habitats. From an economic per­ The value-added approach will by defini­ spective this will involve gaining compe­ tion guarantee protection of the resource. Ac­ tence in measuring the values derived from tions that reduce the quality of the asset will alternativeuses of habitats e.g. recreational reduce the value. Thus actions that lead to re­ and commercial uses. Biological research source depletion that is not sustainable are in­ needs to provide a sound understanding of consistent with a value-added approach. the dynamics of the resource and also the The value-added approach is preferred to impact of human activities on the quality of the regulatory approach because, not only does the asset (which is related to value). it protect the resource, it also facilitates devel­ 3. Use available technology to improve habi­ opment within biological and economic con­ tat management efficiency. There are un­ straints. Key characteristics of the value-added likely to be new instruments discovered to approach are contrasted with the regulatory control human activity in aquatic habitats. approach in Table 2. A key distinction is that the However, technological advances may im­ value-added approach is forward looking and prove the effectiveness of existing methods anticipative. As a consequence, regulations are whether they be input or output controls flexible and strategic. 4. There is large scope for institutional reform to improve the effectiveness of aquatic man­ agement. Institutions need to be flexible, Where does Australia fit into this adaptable, depoliticised, strategic, consulta­ classification? tive, anticipative and conflict reducing. The Aquatic habitat management in Australia is Commonwealth has considered this issue moving towards a value-added approach. For and chosen a statutory authority. What example introduction of individual transferable should the States do? Options include: quotes (ITQ's) in the tuna fishery has assisted to a statutory authority like the Common­ increase the value of the fishery (Geen and wealth's; Naylor 1989). However, most managers would also agree that there are many deficiencies with a Fisheries Board consisting of gov­ the present system. The challenge for the 1990s ernmentand industry representatives; is to build on the progress to date and to strive for and a full value-added approach. an independent Fisheries Commission conducting periodic audits of fish habi­ tats and reporting to the Government What is required to implement the (analogous to the role performed by value-added approach? the Industry Commission in economic development). I. Habitat managers need to develop a value­ added mission. They need to think in te1ms Buchanan (1987) argues that it may be of values and recognise that in most habi­ more effective to improve economic wel­ tats, the present use pattern will not be fare by changing the institutions and rules maximising the value of the resource. Man- governingthe use of resources to obtain a

162 Bureau of Resource Sciences Proceedings result that more accurately reflectsthe pref­ A preferred option is to introduce a value­ erences of stakeholders than to develop strat­ added approach. Rather than just protecting the egies (techniques) to improve efficiency resource, a value-added approach seeks to de­ within the current rules. In some aquatic velop the resource and maximise the value of habitats, there may be scope to develop the asset through varying exploitation levels, common property management regimes and utilisation of the resource by competing rather than continue with management pro­ participants. Development opportunities are grams that seek to strengthen individual exploited so that management becomes forward participants' prope11y rights. looking and strategic. Implementation of a value­ added approach will increase the contribution of 5. Information and education of industry and the habitat to the welfare of society. the public are essential elements of a value­ added approach. Effective debate on alter­ native options must be based on accurate information. This must be disseminated to References all stakeholders. Anderson, L.G. (1985). Potential economic benefits from 6. Increased emphasis needs to be given to the gear restrictions and licence limitation in fisheries regulation. Land Economics 61(4), 409-418. process of fisheries management i.e. con­ sulting with industry, developing, planning Buchanan,J.M. (1 987). The constitution of economic policy. 77(3), and recommending policy. A characteristic The American Economic Review 243-250. of the value-added approach is shared own­ Cornes, R. and T. Sandler (1984 ). Easy riders, joint produc­ ership of the problem and the solution. The tion and public goods. Economic Journal 94, 580- fisheries management development proc­ 598. ess will to a large extent determine the Geen, G. and M. Naylor (1989). Individual Transferable extent to which problems and solutions are Quotas and the Southern Bluefin Tuna Fishery: Eco­ owned by stakeholders. nomic Impact. Occasional Paper 105, Australian Bu­ reau of Agricultural and Resource Economics, AGPS, Canberra. Gordon, H.S. (1954). The economic theory of a common Summary property resource: the fishery. Journal of Political Economy 62, 124-142. Alternative uses of aquatic habitats place de­ mands on the resource that sometimes exceed Gravelle, H. andR. Rees ( 1981 ).Microeconomics.Longman, the capacity of the habitat to meet the demands. New York. This leads to overexploitation, permanent re­ Kratilla, J.V. and A.C. Fisher (1975). The Economics of source depletion and reduced economic welfare. Natural Environments: Studies in the valuation of Commodity and Amenity Resources. James Hopkins Management authorities have typically re­ University Press for Resources In the Future, Balti­ sponded to the potential problem of more. overexploitation by introducing a regulatory Mitchell, R.C. and R.T. Carson (1989). Using Surveys to management approach that protects the resource. Value Public Goods: The Contingent Valuation This approach can be extremely effective in Method. Resources In the Future, Washington, D.C. maintaining the resource. However, a regulatory Tietenberg, T. (1988). Environmental and Natural Re­ approach is often inflexible and inefficient. source Economics, Scott, Foreman and Company, Moreover, it may restrict the extent to which the Illinois. resource contributes to economic welfare. Re­ duced welfare is expressed through a reduced value of the habitat relative to what it could be under an alternative managementarrangement.

Bureau of Resource Sciences Proceedings 163 Table 1. Classification of uses

Nat11reof Category Descri ption demand

Participtive Depletion and depletive Space 2 Participative Space and non-depletive 3 Non-participative Sustainability and non-depletive

Table 2. Characteristics of the regulatory and value-added approaches

Reg u latory approach Value-ad ded approach

Key value is the stock Key value is the value of the asset Protects the stock Develops the resource Current problem Forward looking and oriented anticipative Inflexible Flexible and strategic Consultative Highly consultative Political Depoliticised Conflict Reduced conflict

164 Bureau of Resource Sciences Proceedings DISCUSSION OF SESSION 6

Recorded by J. Robertson GBRMPA P.O. Box 1379 Townsville QLD 4810

Each panel presentation was followed by a time Peter Young asked how the concept of for questions, after which the session was opened multiple use systems would fit into the Western for more general discussion. Australian Water Board's proposed sewage outfall and the accompanying research Following David Pollard' s panel presenta­ programme being developed to evaluate the tion, John Koehn expressed some doubt as to assimilative capacity of that ecosystem. David whether conservation areas were practical in Pollard replied that sewage input should be freshwatersystems as it would require placing a considered as one component of multiple use. national park around the whole catchment area. Sewage outfalls should be located where they He suggested that, apart from small areas such as have minimal impact on the refugia. small catchments or headwaters, a more inte­ grated approach is required in which the key Jim Puckridge pointed out that multiple factors causing detrimental effects are identi­ use is not a panacea. It can be very expensive fied. In addition, limits or tolerances should be and require more substantial expertise than established in order for amelioration to occur. single use refugia. He agreed with John Koehn David Pollard agreed that freshwater systems that an integrated management approach is require a different management approach but required in freshwatersystems but there is still nevertheless the reservation approach was still a case for reserving important or sensitive worth considering in some cases. areas such as highly developed flood plain areas or internal deltas within a multiple use Bryan Pierce supported the comments of catchment system. David Pollard emphasised John Koehn in that protected areas may be appli­ the need to be aware of the increasing economic cable where a fish species may have a limited value of non-consumptive uses eg. tourism on distribution or range but not in open river sys­ the Great Barrier Reef, and start catering for tems such as in South Australia. He suggested them now. that we should be considering, as another alter­ native, multiple uses, which are really multiple Following Andrew Staniford' s panel abuses of the system, and developing ways in presentation, Peter Young enquired whether a which these uses are not so destructive. David situation may arise under a value-added Pollard pointed out that the fish stocks in the area approach, where no fishing at all would occur surrounding the refugia need to be managed on but rather areas being solely reserved for tourist the traditional fisheries basis. The insurance usage. Andrew Staniford agreed that was a policy is the large refuge that allows fisheries possible outcome but suspected it was managers a 'second go' if initial management improbable until there is an alternativesource plans in the surrounding areas are ineffective. of food fish eg. fromaquaculture.

Bureau of Resource Sciences Proceedings 165 Murray MacDonald endorsed the value­ resources, which encompasses a number ofusers added approach and quoted figures placed on besides just fisheries managers, requires an coastal wetlands by the National Marine Fisher­ institutional framework where either single ies Service in the USA. He queried, however, to bodies or networks of agencies are organised what extent trying to put some kind of economic and able to work cooperatively. This would value on these resources is going to compromise seem to indicate that the Australia's cmTent the ability to equitably allocate the uses. Andrew system is heading in the wrong direction. Andrew Staniford replied that allocation is difficult but Staniford pointed out that this is only one requires an understanding of the values of a approach of three he presented and which may particular asset in its various uses; and how that not necessarily be recommended, but we need to resource is shared between the alternative op­ look at what options are available to make our tions that are available for that resource. current institutions more effective. John Glaister commented that basic values Jeremy Prince felt that in contrast to the are part of a framework upon which people react protected area approach in which nobody owns to different management alternatives, and val­ or cares for the resource, the value-added ues should be expressed in more than just dol­ approach is superior as it is in the owner's long lars and cents. It was recognised at the Athens term interest to care for and monitor the resource. conference that for better fisheries management John Glaister said that in industries where we need institutions that are more diverse, crea­ user group interaction was well developed, such tive and responsive to ecological and social as the US Forestry, user group participation complexity and uncertainty. This requires co­ generated more conflict with the industry management institutions that incorporate inter­ managers than before user groups became est, knowledge and wisdom of all resource users involved. He repeated earlier comments that not just fishermen. Andrew Staniford responded fishery management is getting away from the that at present, as fisheries economists, we role of fisheries biologists but not fisheries haven't enough expertise to place a dollar value scientists. to resources with any accuracy but it certainly helps to think in these terms or to identify some Jim Puckridge believed that multiple use other semi-quantitative measure of the benefits has the potential for education and resource or cost of a resource. He considered the key ownership but he expressed some caution that issue for effective fisheries management is to long term ownership in agricultural industries develop, rather than look at problems now, has not necessarily resulted in the conservation likely 10-20 year scenarios for a particular of the resource. Russell Reichelt commented fishery and begin working with various users in that, in his understanding, the multiple use system that fishery to think through those scenarios so on the Great Barrier Reef was introduced to that strategies can be developed before prob­ minimise conflictrather than underpinning any lems arise. fundamental set of strategic principles other than to manage the reef wisely. Russell Reichelt opened the general disrnssion of Session 6 by commenting that Barbara Richardson suggested there is scope multiple use leads to multiple owners, and, in in both the multiple use protected areas and the the habitat management scene, multiple value-added approach. What is required is to regulators eg health, environmental and fisheries come together in a planning process as has been agencies, which would indicate that institutional done in terrestrial systems, to consider multiple arrangements are a key to effective management. use zoning that takes into account the different Ross Winstanley was concerned that this sensitivities, the appropriate uses of those areas, approach to the management of aquatic and the conservation and sustainable use of

166 Bureau of Resource Sciences Proceedings those areas. The planning framework on an ship to hand it over to a particular user group. institutional basis should have an integrated This is not always the case. He went on to say approach with fisheries management being the that the value-added approach can be success­ major focus. The plan should incorporate other fully integrated into the strategic planning proc­ factors including value-added principles in order ess if it is defined, rather than in economic terms, to make more integrated decisions in all of our as what the various stakeholder's interests are waterways. Murray MacDonald stated that the and the perceived benefits they receive fromthe multiple use concept has been discussed at a various uses of the resource. number of national forums over the last l O years. Russell Reichelt asked Peter Young how These forums have emphasised the need for a much strategies such as Ocean 2000, Coastal strategic planning process to accommodate, Zone Strategy influence CSIRO's research besides fisheries, a large range of legitimate and planning on environmental issues. Peter Young possibly conflicting uses of resources. This stated that he wished CSIRO was more involved planning process should involve participation by in these initiatives. He also emphasised some both government and community stakeholders. caution over property rights as it may be He felt that this process should be emphasised in economically viable to fish a stock down, then a number of current initiatives at a national level get out as was practised on whales along the east such as Ocean Rescue 2000 and the National coast of Australia. Conservation Strategy. David Pollard supported previous comments Bryan Pierce asked Andrew Staniford to that a much broader value-added approach, rather cite examples fromother natural resources where than a straight economic approach, needs to be the value-added approach has worked to enhance taken as you may preclude other alternativeuses the sustainability of that resource. Andrew for a short term economic gain, eg. fishing vs Staniford replied that the developments in the fish-watching. Andrew Staniford distinguished tuna fishery since quotas were introduced has between commercially driven values and what given it a greater chance of being sustainable. he refen-edto in his talkas a value-added approach The emphasis is now placed on cultured fish and that includes non-commercial values. He agreed how they complement the wild stocks. He also with Jeremy Prince that property rights can be agreed with the comments by Murray MacDonald effective in some situations but in others there is on the advantages of the strategic planning process a need to develop a common property approach and stated that unless all stakeholders are where the users of the resource have shared involved, the plans will be developed by ownership of the problems and solutions and are politicians with the interest of political lobby committed to implementing these. groups tending to dominate. Russell Reichelt asked Rob Lewis to what Jeremy Prince commented that if we are extent would the development of the National able to put value to resources, the strategic plan­ Coastal Strategy or Ecologically Sustainable ning process would become bogged down in Development principles assist his department community and government committees. Rather with the development or loss of sea grass areas a group of individuals should actually own the in South Australia. Rob Lewis thought these resources thereby attaching their own value and strategies have been very valuable to him as a ensuring the sustainability of the resource. Mun-ay planner, particularly Ocean 2000 in that it deals MacDonald said that Jeremy Prince's comments with issues and involves the participation of were fine if you make the assumption that fisher­ commonwealth, state and local user groups. ies is the only use of those resources and the This has been the approach of the marine scale community who own the common property re­ fishery in South Australia and the industry has source are quite happy to relinquish their owner- been fully supportive of this method.

Bureau of Resource Sciences Proceedings 167 Jeremy Prince explained that fishing down process not just in terms of the interaction a resource for short term economic gain is valid between user groups, identifying management if you have a lot of virgin biomass but such objectives and ownership but also for fisheries situations are rare in the current day. It is of long managers in receiving a cross fertilisation of te1m benefit to buy up undervalued resources ideas and feedback in ways to best manage or and rehabilitate these, whereas the common improve management in the future. situation discourages people receiving the ben­ efit of their own rehabilitation efforts. David Pollard refuted Jeremy Prince's comments by suggesting that a broader approach than re­ source ownership is required and no one should own a resource because it precludes all other possible alternative uses in perpetuity. Andrew Staniford agreed with these comments. Russell Reichelt stated that at present the fishery scientist is held back because of the lack of long term data sets on which to base deci­ sions. He asked Andrew Staniford who are the people best suited to adopt the long term view on issues such as data collection and resource man­ agement. Andrew Staniford replied by saying that because of the common property value of fish resources there aren't any incentives to keep long term data sets so there's a strong basis for government intervention in the collection and distribution of these data. Diane Hughes said there is a strong case for education of the users of a resource and the public on how to recognise and improve the value of an asset. Murray MacDonald asked David Pollard to comment on how effective had a strategic man­ agement framework been in achieving equity in the allocation of users in the Solitary Islands marine protected area and to what ex tent had the value of various habitats and resources in that area been recognised. David Pollard considered that the Solitary Islands marine protected area, through public participation in the multiple use zoning scheme, is quite good in its general aims at sustainability and multiple use equity. He was concernedhowever that the area may not sustain long te1m sustainability in biodiversity as it did not contain large protected areas. Barbara Rich;irdson supported David Pollard's comments in saying that the Solitary Islands marine protected area has been a valuable

168 Bureau of Resource Sciences Proceedings SESSION 7

MANAGEMENT (AMELIORATION, ENHANCEMENT, CONSERVATION)

Session Chairperson: B.A. Richardson Session Panellists: R.N. O'Boyle J. Burchmore W. Fulton Rapporteur: D.A. Pollard 170 Bureau of Resource Sciences Proceedings CHAIRPERSON'S INTRODUCTION

B.A. Richardson NSW Fisheries Locked Bag 9 Pyrmont NSW 2009

Introduction The answers to these questions will depend largely upon what we know now and this is The management of fisheriescannot be effective certainly an incomplete understanding. without the integration of stock management with management of the habitat and environment Canada's Department of Fisheries and upon which these living systems depend. Oceans has a policy to increase the productive capacity of habitats for the nation's fisheries As information grows, the relationships resources. This has as its guiding principle that between fish populations and fish habitats there be no net loss of fish habitat and provides become better understood but there remain many for compensatory habitat where losses are likely questions yet to be answered. In the meantime to be incurred through development. policies and management programs need to be implemented to protect and conserve, and where NSW Fisheries has as its major objective to appropriate restore, remaining fish habitat protect the diversity of habitats as functional quality and quantity. units with special emphasis on protection and restoration of critical habitats. In developing policies the objectives must be clearly defined and the expected outcomes identifiable or measurable. Fish habitat management programs need to set a policy Habitat management strategies framework including the general underlying question, i.e. What is happening tofish habitats Strategies involved in habitat management pro­ and what do we need to achieve? grams include amelioration, enhancement and conservation measures. For the purposes of this Should we aim to: workshop, amelioration is defined as measures restore or rebuild lost habitat? to improve a degraded environment or restore a • maintain the status quo-no further loss? habitat. Enhancement can be considered as the means to add some additional productivity. Con­ maintain the area of critical habitats as servation is the suite of measures that aim to understood? protect the remaining natural habitats and eco­ • protect the diversity of habitat types and system integrity. their relative proportions? Dete1mining when and where these strate­ And: gies are to be used requires localised knowl­ • What environmental factors are central to edge, accurate recognition of the problem and a effective habitat management? capacity to monitor the ecosystem response.

Bureau of Resource Sciences Proceedings 171 Amelioration The objective in this strategy would be to increase the ecosystem productivity, fish abun­ The types of habitat degradation or inadequate dance or diversity, or possibly to replace or environmental management which are appro­ increase the area of a particular habitat. priate for amelioration include: The scope to undertake enhancement may controlling point source pollutants­ be affected by whether or not the owner of the pollution reduction programs; land, lake, seabed etc. is in agreement. Generally restore flushing and tidal exchange to most works would be undertaken on impacted wetlands or landlocked coastal Crown-owned lands or leaseholds. This is the lakes; case for a project being undertaken on Kooragang Island in the Hunter River, NSW, whereby revegetation of aquatic and riparian habitats; leasehold land is proposed to be re-levelled and • returnstreamflows to meet instream needs; channels created to provide for wetland creation. • provision of fish passage facilities. Compensatory habitat creation is a tool which could be legislated for as a means to Who's responsible? amend damage from illegal activities or The legislative provisions and agency restitution. The more likely application is the responsibility may well lie in several different negotiation of compensatory habitat with government portfolios. Furthermore these developers who seek to destroy or modify an programs may also require a coordinated effort area of naturally occurring habitat. The costs are between private companies, individual land met by the proponent developer in a form similar owners, and local government. Often a to "polluter pays". One needs to ask: Is this combination of policies and legislation is likely to be as effective as natural habitat, and if required to achieve amelioration. not, how much replacement habitat would be appropriate? Who should pay for amelioration? The costs of undertaking these programs could be subsidised by levies on polluters, poor land Conservation managers, large scale water users, etc .. Given One of the first questions to consider is: Should the problem of identifying individuals responsi­ we concentrate on species conservation or ble in the majority of cases, these costs are more ecosystem conservation? The capability of the commonly borne by governments. This may aquatic environments to be productive and partially account for the limited amelioration sustain fisheries is dependent on a functional which is undertaken. ecosystem. However, in the case of endangered or threatened species, it is difficult to manage the problem solely by general ecosystem Enhancement conservation. Enhancement is usually applied where a A strategy for conservation of habitats and particular opportunity exists or is created. ecosystems is needed in day to day management Compensatory habitats, artificial substrates and programs. Without complete knowledge of the man-made habitats, or stocking programs could ecosystem, I believe it is most important to be included in this category. These opportunities maintain the diversity of habitats and the pro­ are a valuable learning tool as well as a step p01tional representation wherever possible. This towards returning some component of lost begs the question: Do we know enough to only productivity. protect perceived critical habitats?

172 Bureau of Resource Sciences Proceedings Conservation can be undertaken in the form of guidelines and policies for assessing devel­ opments and environmental impacts. The ob­ jective in this strategy is to identify any activities which may have unacceptable impacts on aquatic ecosystems or to minimise the impacts arising fromdevelopments which are seen as justifica­ tion in the public good. Fisheries legislation and environmental planning legislation are both important to achieve this. However this alone could continually reduce the quality and quan­ tity of fish habitats without the balance of amel­ ioration and enhancement strategies. The development of a representative re­ serve system which would allow long term conservation of habitats and communities is one appropriate conservation measure which can be an effective addition to fisheries closures which protect habitat. The size and selection of re­ serves can vary but there seem to be greater benefits to be derived from larger areas with some form of buffer area than small isolated pockets as protected areas. A further means of protecting fish habitats can be by environmental protection zones incor­ porated in local and regional planning instru­ ments as well as reserves and closures under fisheries legislation. Community education and awareness is most important in delivering con­ servation programs to greatest effect(Moberly this meeting). The public can participate in the planning process and raise the level of perform­ ance of local governments in protecting fish habitats. Furthermore, the community, includ­ ing user groups such as fishermen or passive users such as conservationists, divers etc., can participate in habitat management programs, eg. planting mangroves, clean up programs. The above ideas are suggested strategies and concepts and are by no means comprehensive. The workshop session may challenge and debate these issues with a view to proposing more effective means of sustaining fish habitats.

Bureau of Resource Sciences Proceedings 173 THE MANAGEMENT OF MARINE HABITAT

R.N. O'Boyle Marine Fish Division Bedford Institute of Oceanography PO Box 1006 Dartmouth Novia Scotia Canada B2Y 4A2

Abstract Introduction The management of marine habitat involves In Canada, as in other parts of the world, marine issues that are chemical, biological and physical habitat problems can be considered under three in nature. The variety of impacts and the com­ broad categories. Chemical issues involve the plexity of marine ecosystems presents special impacts of oil spills, both from rigs and vessels, challenges to habitat managers and calls for and exploration. The ocean dumping of chemical careful attention to management functions and waste can be considered under this category. institutions. Cariadaadopted a new approach to The second set of issues are biological in nature, habitat management in 1986, elements of which generally involving the effects of eutrophication are discussed in this paper. The main features of on coastal waters, resulting from runoff of this policy relate to the objective of overall net agricultural land, sewage from urban areas and gain in productive capacity and how this is industrial waste from fish processing, fertiliser achieved through conservation (no net loss prin­ plants and even aquaculture. For instance, there ciple), restoration and development. Models has been much discussion in Europe on the that quantify these principles and thus provide linkage between human-generated targets for management are only now appearing, eutrophication and phenomena such as red tide examples of which are given for aquaculture and the incidence of Phocine Distemper Virus sites. These represent a good starting point for (Rosseta/.1992). the development of more comprehensive views of the ecosystem both in relation to aquaculture Finally, there are the impacts of physical and elsewhere. structures on the habitat. These include barriers (Canso Causeway, link to Prince Edward Island, An extensive set of regulatory measures dam for Fundy Tidal Power), marine debris has been established to provide managers with (plastics, discarded nets which can" ghost-fish") the tools to manage habitat development to­ and disruption of the benthos ( ocean mining, wards the objectives. However, in the case of the fishing gear impacts on bottom, laying of cables offshore marine environment patticularly, much and pipelines, etc). A numberofthese are detailed needs to be done to ensure the long-term moni­ in Messieh et al. (1991). toring of human impacts on the habitat. Recent initiatives in this are presented. Current efforts All these issues are common to most parts to integrate the disparate data bases used in of the industrialised world and have elicited support of habitat decision-making are also dis­ various management activities as and when they cussed. The paper ends with a description of the arise. However, to be truly effective, the re­ consultative process used by Canada to review sponse of managers to habitat issues must be proposals that have potential habitat impacts. based on a system which has well defined goals,

174 Bureau of Resource Sciences Proceedings regulations and monitoring activity. Otherwise very difficult to undertake. In fisheries, the one runs the risk of a patchwork approach to focus of management is the biological stock. habitat management. This considerably simplifies the situation in relation to goal setting, regulation and monitor­ In 1986, Canada adopted anew approach to ing. With habitat, on the other hand, even defin­ habitat management, after an extensive period ing the ecosystem is not a trivial matter. of consultation. In this paper, I will discuss the Nevertheless, it is axiomatic that in order to main elements of the current policy and its effectively manage, the first step is to define the implementation. As well, problem areas will be boundaries of the "management unit". Too of­ identified together with some of the current ten, this has been given little consideration in the programs that are underway to address these. definition of habitat management systems. OffNova Scotia, progress has been made The management unit on the preliminary identification of a number of ecosystems (Mahon and Sandeman 1985). The Any discussion on the management ofhabitat­ Gulf of Maine ecosystem, characterised by a marine or otherwise-must start with a defini­ mixture of warm and cold water species, stretches tion of habitat. In the Canadian Fisheries Act, from CapeCod to midway up the Scotian Shelf habitat is defined as "spawning grounds and (Figure 1 ). The Laurentian Ecosystem contin­ nursery, rearing, food supply and migration ues fromthere, across the Laurentian Channel areas on which fish depend directly or indirectly along the southern coast of Newfoundland to in order to carry out their life processes". Thus, meet the Labrador Ecosystem which continues it is that part of the ecosystem, including the north up the Labrador Shelf. The boundaries of biotic and abiotic components, upon which a these ecosystems tend to coincide with major fish depends. The Act is silent on the issue of the physical oceanographic featurespresent on the importance, commercial or recreational, of the coast, lending support to the hypothesis that the fisheries and indeed is broad enough to include productivity of these communities is largely the entire ecosystem. In recent years however, related to the prevalent environmental condi­ the management of fish habitat has been di­ tions. rected towards those species that are economi­ cally or socially important to Canadians. It is As yet, those ecosystem boundaries have becoming increasingly evident that many user not been used to assist in the management of groups are interested in access to the marine offshore habitats as more work is required to environment, most notably tourist interests, and confirm and refine the integrity of these units there is growing concern that degradation of (Mahon et al. 1984). Nevertheless, habitat man­ marine habitat will, in the long term, have nega­ agers will have to be aware of the characteristics tive impacts on other parts of the environment. of the ecosystem with which they are dealing. It is evident then that as the use of habitat Definitions of characteristics, such as the ones evolves, so too will the focusof its management. presented, are a usefulfirst step in this regard. Current Canadian legislation appears flexible enough to accommodate this. In addition, as with fisheries management, it is important to The goals of habitat management keep in perspective the economic and social Management goals can be considered as being consequences of habitat degradation, and thus composed of objectives which define what it is its management, on the human population. that one wants to achieve, and strategies which Given that habitat management can be con­ are quantifiable targets or constraints by which sidered synonymous with ecosystem manage­ one measures the success ( or otherwise) of ment, it is easy to understand why it has been so management.

Bureau of Resource Sciences Proceedings 175 In Canada, the long-term objective is the These models summarise our knowledge achievement of an overall net gain in the pro­ of the dynamics of marine populations and ductive capacity of fish habitats (Anon. 1986). provide understanding on the impacts of har­ This is considered to be possible for anadromous vesting on yield, recruitment, population growth and certain freshwater and shellfish species but and abundance and so on. They thus provide the more limited in marine ecosystems. Neverthe­ means to quantify overfishing, and therefore less, the long-term thrust of the policy is to provide guidance for the control of harvesting regain habitat to compensate that which has levels. already been lost. Development of strategic models with the This objective is achieved through three ensuing targets/constraints for habitat manage­ initiatives: ment, is not as advanced as for fisheries man­ 1. Conservation-Maintain the current pro­ agement. There is an urgent need for these, ductive capacity offish habitats supporting given the rapidly growing encroachment on Canada's Fisheries resources, so that fish habitat that is occurring around the world. Given suitable for human consumption may be the complexities of the ecosystem it is under­ produced. This strategy is synonymous with standable that model development has been the No Net Loss Principle. slow. This is not to say that there has not been progress. Gordon ( 1992) for instance, reviews a 2. Restoration-Rehabilitate the productive number of significant efforts in the North At­ capacity of fish habitats in selected areas lantic. Much more is still required. There may where economic or social benefits can be be a temptation to resist model development achieved through the fisheries resources. until more data are collected. This would be a This is to correct past mistakes (ie installa­ mistake. Silvert (in press) shows that it is im­ tion of dams without fish passages, sewage p011ant to create models, based on first princi­ treatment plants, etc). ples and simple assumptions now, that can be 3. Development-Create and improve and updated as more is learnedabout the system in generally enhance fish habitats in selected question. Through the constant interaction be­ areas where the production of fisheries re­ tween field and model, understanding of the sources can be increased for the social or cause and effect of habitat management can be economic benefit of Canadians. dramatically improved. The combination of conservation, restora­ Silvert (in press) illustrates how simplified tion and development initiatives leads to a net models can be constructed to evaluate the im­ gain in overall habitat productivity. While this is pacts of salmon aquaculture sites on habitat. As simple in concept, it does not help unless we with fisheries models, the impacts can be evalu­ have targets and constraints by which we can ated at various levels. This is an important define and measure levels of conservation, res­ consideration in that it partitions the overall toration and development. problem into smaller, more manageable units and is perhaps an approach that could be adopted In fisheries management, mathematical for other habitat problems. formulations called strategic models, such as Surplus Production and Dynamic Pool models The first level that he considered was at the (O'Boyle 1987), have been used to define tar­ inlet or regional scale. He described total ac­ gets and constraints on harvesting such as Maxi­ ceptable bay production as a function of depth, mum Sustainable Yield, F AX and minimum flushingtime, nitrogen production and the ca­ M Spawning Stock Biomass. pacity of the bay to handle this production, or

176 Bureau of Resource Sciences Proceedings Nitrogen Over the long term, the cumulative effects of this Maximum Lo dLimit process will be felt. Thus there is real benefit to ( � ) Production = f Nitrogen providing a means of measuring and assessing per Unit Area Production this incrementalism. All these parameters are measurable or can The above models were formulated for be derived from previous studies. The maxi­ aquaculture applications and are at an early stage mum aquaculture production allowed in the bay of development. There is a need to develop mod­ that maintains conservation of the habitat can els forother areas of habitat usage so that manag­ then be calculated. ers can be provided with quantitative measures of conservation, restoration and development. The next level considered was at the local scale involving inter-site impacts and is there­ fore concerned with placement of aquaculture The controls of habitat management sites within the inlet. At this scale the localised effects of benthic disposition are important, There are two aspects of control-regulation to which can be mitigated against by defining a ensure that habitat developments are consistent minimum site depth for a particular size and with the goals of management, and monitoring to level of site productivity. Silvert (in press) de­ ensure that the regulations are having the desired scribes the minimum allowable site depth as a effect.The monitoring activity may lead not only complex function of total production, settling to changes in the regulations but also, through speed, aquatic transport and bottom type. Again, scientific research, to modificationsin the strate­ the manager can then judge the appropriateness gic models. of a particular cage site at a given depth. The last sc;aleto consider is at the internalor Regulation cage level wh�re oxygen depletion within the When a development proposal is received by the cage site itself must be considered. Here, the Canadian Department of Fisheries and Oceans size of the farm is related to its production (DFO), a hierarchy of regulatory measures is capability, or used to ensure attainment of the conservation (no net loss) objective: �:���:n =f ( Spe�����pth )x 1. The natural productive capacity must be Length of Site Oxygen Consumption maintained through redesign of the proposal, location of the project at alternatesites and, Ambient Lowest in the case of chemicals, pollution control (Oxygen - Acceptable) devices. If this is not possible (for other than Level Oxygen liquid waste discharges) then, Level 2. Compensatory options are pursued, includ­ Thus, the physical dimensions of the farm ing like-for-like habitat on the same site, can be modified to be compatible with the like-for-like habitat at an alternate site or existing environmental conditions. finally enhancement of the productivity of the existing habitat. If these options are not At present, while there is recognition that possible; then, these levels interact, little has been done to quantify this. This is an important area of study. 3. Artificial production may be considered as There may be a tendency in the evaluation of long as the objectives of local fisheries are small, localised development proposals to grant observed and the methodology is practical approval where effectsare too small to measure. and proven.

Bureau of Resource Sciences Proceedings 177 There is a considerable package of legisla­ to investigate the impacts offishtrawling on the tion (Anon. 1991) which provides the enforce­ benthos, similar to the studies conducted by ment tools of regulation including fines, the Sainsbury (1991). In the longer term, it may be requirements for safe fish passage, minimum possible to integrate this benthic monitoring flow requirements, fish-way protection, physi­ activity with annual groundfish trawl surveys. cal disruption of the habitat and its pollution. An important aspect of monitoring is, as Most of these regulations are more relevant to stated earlier, the provision of a decision-mak­ the inland and coastal waterways but can be ing facility to managers to assist in the initial extended to the marine environment as required. review of development proposals and their en­ There are a number of reporting require­ suing impacts. In fisheries, extensive informa­ ments in the Canadian Habitat legislation that tion systems have been developed to provide the are of importance. Besides the ongoing require­ necessary input to management. Comparable ments, it is the responsibility of the developer to systems are only now being developed for habi­ provide the analyses of potential impacts of the tat applications. development on the habitat. This will be dis­ cussed further below. One of these is being developed as pa1t of a project, on the L'Etang estuary in southwest New Brunswick, to provide the basis of the Monitoring evaluation of the suitability of aquaculture sites. For the marine habitat, most of the monitoring The work of Silvert (in press) and Silve1t et al. effort has been conducted close inshore. For (1990), mentioned earlier, is part of this project. instance, there is an extensive network of moni­ toring sites to evaluate levels of coastal The structure of the decision-making sys­ phytoplankton, with the focus on those capable tem cun-ently under development is presented in of producing phytotoxins. Over the long term, Figure 2 (Keizer, pers. comm.). The central this information will be useful in evaluating feature of the system is a GIS-based analysis whether or not these events are related to anthro­ package. This package can access a number of pomorphic trends. For instance, it has been pro­ data bases, ranging fromhuman activity to fish­ posed that the mass mortality of harbour seals in eries statistics, available in a number of differ­ Europe in 1988, caused by Phocine Distemper ent organisations and locations, and allow the Virus, might be related to the levels of collation of disparate data over differentspatial immunosuppressive pollutants (Ross et al. 1992). scales. Interestingly, this requirement, driven by the complexity of habitat issues, has called In the offshore area, while effectsof bottom for the definition of computer communication disturbance have been documented (Messieh et standards, policies on access to data bases, and al. 1991), there has been no long-term program consideration of institutional arrangements to in place to track decadal scale changes. How­ facilitate data sharing. ever, as a consequence of consultations con­ ducted in 1989 (Hache 1989), a program has On the other side of the GIS are decision­ been established to evaluate the impact of trawl­ making models which would be unique for each ing on the benthic habitat. Thus far, the project habitat issue. For aquaculture, these models has focusedon the development of gear capable would allow the manager to survey all informa­ of sampling the bottom, including side-scan tion relevant to a specific locale under consid­ sonar mounted on a towed vehicle, epibenthic eration for site placement, as well as accessing sled equipped with video camera and hydraulic­ other models available to evaluate impacts. Ini­ powered, video-equipped bottom grab( 0 'Boyle tially, the system may only be a pointer to these et al. in press). This project will use the opp01tu­ models but in the future it will allow options nity provided by areas closed to fishing activity investigation by the decision maker.

178 Bureau of Resource Sciences Proceedings It is envisaged that this informationsystem This process can either lead to further pub­ will become a key component of the evaluation lic consultations (major impacts projected) or process for habitat proposals. Nonetheless, while more limited consultation with the immediate the system will provide the necessary technical proponents (minor impacts projected). If public backup, an extensive consultative process is consultation is required, the Minister of Fisher­ also required to evaluate habitat-related pro­ ies and Oceans recommends to the Minister posals. Experience has shown with other man­ responsible for the Federal Environmental As­ agement systems that consultation is a key sessment Review Office(FEARO) that a public element that requires careful consideration review panel be appointed. The latter is a non­ (O'Boyle submitted). partisan board of experts to which DFO and the proponents, as well as the general public, make submissions. This board then considers the in­ put and makes a recommendation to the Minis­ The consultative process ter. The proponent can appeal this decision The process used by Canada to evaluate devel­ directly to the Minister. Ultimately the latter opment proposals is given in Figure 3. All makes the final,binding decision. Canadian federalgovernment departments are Whilethis process is involved, it has worked required to conduct evaluations for projects relatively effectively in decision-making on under their jurisdiction as part of what is re­ habitat issues. ferred to as the Environmental Assessment Review Process (EARP). The initial informa­ tion and evaluation report (Environmental Im­ pact Statement) prepared by the project Concluding remarks proponent is received by the DFO Habitat Man­ The management of Marine Habitat is compli­ agement Branch for their evaluation. A consid­ cated by the scale of the problem and complex­ erable consultation process now commences ity of ecosystems. However, this enforces the during which the potential biological, chemical need for a structured approach to management and physical impacts of the project are as­ involving consideration of the management sessed. It is during this phase that the objectives units, objectives, targets, regulations, monitor­ of conservation, restoration and development ing and consultative processes. Canada has made are assessed. Until recently, regional scientists significant progress in establishing a manage­ had to undertake these evaluations. In 1992, the ment policy, regulatory framework and con­ Canadian Atlantic Fisheries Scientific Advi­ sultative process to guide its management of sory Committee (CAFSAC) struck a new sub­ habitat. Considerable work is still required to committee on habitat to serve as a scientific define models of the cause and effect of impacts peer review forum on habitat issues. This pool­ as well as to establish effective monitoring ing of scientific expertise to consider resource systems. Work in these areas has been initiated issues has been central to the success of other and will require a sustained effort to ensure the management agencies such as North Atlantic realisation of an effective system for marine Fisheries Organisation (NAFO), International habitat management. Council for the Exploration of the Sea (ICES), Canadian Atlantic Fisheries Scientific Advi­ sory Committee (CAFSAC) and International Acknowledgements Commission for the Conservation of Atlantic Tunas (ICCAT), and will greatly facilitate ef­ The author gratefully appreciates the input and forts to provide informed advice on habitat review comments received fromDon Gordon, management. Bill Silvert, Paul Keizer and Dave Marantz.

Bureau of Resource Sciences Proceedings 179 References Silvert, W. (in press). Assessing Environmental Impacts of FinfishAquaculture in Marine Waters. Aquaculture. Anon. (1986). The Department of Fisheries and Oceans Policy for the Management of Fish Habitat. DFO/ Silvert, W.L., P.O. Keizer, D.C. Gordon and D. Duplisea 3524 Minister of Supply and Services Canada. 1986. (1990). Modelling the Feeding, Growth and Metabo­ Cat. No. Fs 23-98/1986 E. lism of Cultured Salmonoids. ICES. C.M. 1990/F.8. Sers.O. Anon. (1991). Canada's Fish Habitat Laws. DFO/4438. Minister of Supply and Services Canada. 199 I. Cat. No. Fs 23-40/1991 E. Gordon, D.C. (1992). Current Applications and Future Developments in the use of Mathematical Models in the Implementation of Monitoring Programs and Re­ gional Assessments. lnt. Council for the Exploration of the Sea C.M. 1992/Poll.: 9, Sess. V, Annex 3.

Hache, J .-E. (1989). Report of the Scotia-Fundy Groundfish Task Force. Minister of Supply and Services Canada. Cat. No. Fs 23-157/1989 E.

Mahon, R. and E.J.S. Sandeman (1985). Fish Distributional Patternson the Continental Shelf and Slope from Cape Hatteras to the Hudson Strait: A Trawl's Eye View, pp.137-152. In: R. Mahon [ed] Towards Inclusion of Fishery Interactions in Management Advice. Can. Tech. Rep. Fish. Aqua/. Sci. No. 1347.

Mahon, R., R.W. Smith, B.B. Bernstein and J.S. Scott (1984). Spatial and Temporal Patterns of Groundfish Distribution on the Scotian Shelf and in the Bay of Fundy, 1970-81. Can. Tech. Rep. Fish. Aqua/. Sci. No. 1300. Messieh, S.N., T.W. Rowell, D.L. Peer and P.J. Cranford ( 1991 ). The effects of Trawling, Dredging and Ocean Dumping on the Eastern Canadian Continental Shelf Seabed. Continental Shelf Research 11, 8-10. O'Boyle, R. (1987). Approaches to Fisheries Management in the North-WesternAtlantic-A Canadian Perspec­ tive. Marine Law Institute, Univ. Maine School of Law, Portland, Maine, 482 pp. O'Boyle, R. (submitted). Fisheries Management Systems. A Study in Uncertainty.Can. J. Fish. Aqua/. Sci.

O'Boyle, R., K. Drinkwater, B. Petrie, T. Rowell and P. Vass (in press). The Atlantic Fisheries Adjustment Program. Science Review 1990/91.

Ross, P.S., 1.K.G. Visser, H.W.J. Broeders, M.W.G. van de Bildt, W.D. Bowen and A.D.M.E. Osterhaus (1992). Antibodies to Phocine Distemper Virus in Canadian Seals. Veterinary Record 130, 514-516. Sainsbury, K.J. (1991). Application of an Experimental Approach to Management of a Tropical Multispecies Fishery with Highly Uncertain Dynamics. ICES. Mar. Sci. Symp. 193, 301-320.

180 Bureau of Resource Sciences Proceedings 85 60

82 81 80 79 78 77 76 SS 75 74 d 73 72 71 70 69 68 67 66 50 65 64 63

57 S6 45

40

b

35

50 70 60 Figure 1. The four major clusters of bands using the occurrence of fishes at depths of 50-200 m to identify the marine ecosystems off the Canadian East Coast; a) New England; b) Gulf of Maine; c) Laurentian; and d) Labrador. (from Mahon and Sandeman 1985).

Bureau of Resource Sciences Proceedings 181 Decision-Making Decision-Making Models Models 2

(Aquaculture Sites) (Habitat Sensitivity) �/ I GIS I

Input Data Base Input Data Base Input Data Base 2 3 (Human Activity) (Oceanography) (Fishery) i.e. Licences Figure 2. Relationship among input and decision-making data bases and GIS (Geographical Information Systems) developed as a decision-making system for the L 'Etang Estuary Project.

182 Bureau of Resource Sciences Proceedings STEPl Notification by Information received proponent and on project governmentsources

Assess potential impact on fisheries and habitat

Additional information (if required) (Section 37(1))

STEP2 Examination by Assess alternativesiting or other Fisheries and Oceans, options and discuss with proponent often in consultation with other agencies Assess mitigation options

Assess compensation options (if compensation determined feasible)

Major potential Minor potential impact impact r--···· -, Consult with public, Consult with STEP3 proponent and other proponent and Consultation government agencies interested parties I I I (Section 37 (2)) I STEP4 Proceed as Proceed with Reject Decision proposed conditions proposal

I I I

·� STEPS Monitor compliance L--1 Appeal Audit and effectiveness I

STEP6 Problem correction/prosecution (if required) Enforcement I I

Figure 3. Procedural steps to achieve No Net Loss (from Anon. 1986).

Bureau of Resource Sciences Proceedings 183 MANAGEMENT OF THE ESTUARINE HABITAT

J. Burchmore NSW Fisheries Locked Bag 9 Pyrmont NSW 2009

Estuarine habitats have suffered major disrup­ mangroves, unconsolidated sediments of sand tions this century, and habitats such as seagrass or mud, and saltmarshes. Of these habitat types, beds, mangroves and saltmarshes are all con­ the most threatened are probably seagrasses, tinuing to sufferf rom the cumulative impact of mangroves and saltmarshes. small encroachments-the tyranny of small Seagrasses in particular have suffered seri­ decisions. ous declines. Of the major estuaries in NSW which have been intensively studied, many have lost as much as two thirds of their seagrass beds Issues and problems over the last thirty or forty years. For example, The importance of estuaries in the Clarence River inNSW there were 356 ha of seagrasses in 1942 and only 158 ha in 1981 - Estuaries are ecologically significant areas that a 56% decrease (Shepherd et al. 1989). More provide a variety of habitats for aquatic plants recent research has shown that by 1990 there and animals. Their importance to fisheries and had been an 80% decrease on the 1942 figure. thus the need for their protection, has only really Over90% of the wetlands of the Hunter, Clarence been realised in the past few decades (e.g. Pol­ and Macleay River floodplains have been af­ lard 1976). These habitats play a major role by fected by drainage and flood mitigation schemes. providing nursery areas for juvenile fish as well as shelter, food and breeding areas for many adult fish. Activities liable to affect estuarine habitats Estuaries are areas of considerable signifi­ There are a number of human activities that cance to both commercial and recreational fish­ have the potential to severely impact on estua­ eries. It has recently been estimated that 64% rine habitats (Pollard et al. 1991). The key ones (by value) of the 1987 /90 catch of commercially inNSW are: marketed species in New South Wales are de­ pendent on estuaries during all or part of their • infilling, dredging and extractive life cycles. This equates to a value of$77 million operations; (C. Copeland and D. Pollard, pers. comm). • diffuse and point source pollution; r Estuarine habitats waterf ont developments, such as canal estates; Estuarine fish habitats can be roughly differen­ tiated by vegetation type, sediment type and • marinas and other recreational facilities, depth. They include seagrasses, rocky reefs, such as jetties;

184 Bureau of Resource Sciences Proceedings • road and bridge construction; and argue the case for the retention of one mangrove or a small patch of seagrass that • structural flood mitigation works. may be lost as the result of a development. As a result, over time large areas of impor­ tant habitat are gradually being eaten away. Management problems e) There is a lack of economic and cost/ben­ Conservation, amelioration and enhancement efitstudies. These can rely on commercial of these important fish habitats are honourable fish catch data but this is usually only an ambitions but there are many hurdles to over­ annual estimate. This then ignores the fact come before these can be achieved: that fisheries are renewable resources if managed properly, and thereforehave po­ a) There is eithera lack of adequate legislative tentially an infinite value to the commu­ protection for fisheries habitats, or legisla­ nity. The values of other functions such as tion may rest with an inappropriate agency stabilisation and filtering are often ignored where this provision is not a high priority. and not costed out. For example, there is no direct legislative protection for seagrasses in NSW. f) In mitigation projects there are seldom any acceptable measures of success, e.g. "x% Neither is there legislation which requires of biodiversity returnedafter y years". Of­ compensation/mitigation for habitat de­ ten there are no baselines to determine struction. Instead, there is a reliance on appropriate performance indicators and it time-consuming negotiations throughout is often necessary to rely on the results of planning processes; e.g. during the public only very brief surveys carried out in rela­ exhibition and determination phase of de­ tion to environmental impact assessment. velopments requiring environmental im­ pact statements. b) The final decisions with regard to the de­ Management solutions struction or protection of important fish habitats often rest with other agencies (e.g. Today as managers of estuarine fish habitats, we construction authorities such as the Depart­ are faced with the fact that we may be lacking ment of Public Works) or with different necessary background information,legislation, levels of government (such as local coun­ decision-making ability and resources. What cils). Often the governmentagencies with we do have, however, is the vision and the ideas the largest budgets are in the strongest for habitat conservation, amelioration and en­ positions of control and influence. hancement. c) There is a critical lack of good information Every opportunity must be taken to partici­ bases, particularly on mapping of habitats, pate actively in the processes, whether it be habitat utilisation, necessary buffer zones, attending interdepartmental or catchment man­ etc. Estuarine inventories are perhaps the agement committees, preparing submissions in most valuable management tools, but these response to environmental impact statements are few and far between and are seldom and other planning instruments, presenting evi­ upgraded. There is also a critical lack of dence for Commissions of Inquiry, or merely restoration techniques. undertaking day-to-day negotiations with other agencies. d) There is great difficulty in managing cumu­ lative impacts resulting fromthe "tyranny There are three current case studies in NSW of small decisions". It is very difficult to estuaries which, to varying degrees, all involve

Bureau of Resource Sciences Proceedings 185 concepts of habitat conservation, amelioration Case Study 2-Kooragang Island and enhancement. These may help to highlight Wetland Restoration/Compensation some of the problems and complexities inherent Project in proactive habitat management. Development: Historical reclamation of islands in the Hunter River for industrial land. Wetland areas Cas£ Study 1-Ballina Mangrove were also drained for grazing. Compensation Project Impact: More than 600 ha of Development: Bridge and access road mangroves and saltmarsh has through mangroves. been reclaimed or degraded. Tidal creeks have been Impact: Loss of 8 ha of mangroves. blocked by poor culvert Management Development approved by design. Action: local council on the condition Management NSW Fisheries approached that an equivalent area of Action: key players with the concept mangroves be created. of repairing past damage and Problems: No available area was creating new habitats. A available and there were no jointly-funded feasibility available techniques or report was prepared. baselines. Problems: Community /landowner Solution: Removal of fill from acceptance. Cost effectiveness previously reclaimed of earthworks. Continued industrial land, with various access for utilities. treatments being used to Solution: The feasibility report determine best method for recommended opening and future projects, including: deepening of tidal creeks to - transplanted trees (l-3m). allow tidal inundation and use of experimental plots to - transplanted seedlings (20- determine the best way of S0cm). restoring/creating fish - planted seeds. habitats. - natural recruitment. Results: Unknown at this time. Results: Planted seeds were found to be the best technique, and the resulting mangroves are now Case Study 3-Construction of Third growing successfully on the Airport Runway in Botany Bay reclaimed areas. A large and Development: The third airport runway which diverse fish population has will encroach into Botany Bay. also returned to the area. Impact: Large scale dredging (15 million cubic metres) and reclamation. Loss of 30 ha seagrass, 4 km of sandy beaches, destruction of fishing grounds.

186 Bureau of Resource Sciences Proceedings Management Plan of Management requiring Shepherd, S.A., A.J.McComb, D.A. Bulthuis, Action: monitoring and compensatory V. Neverauskas, D.A. Steffensen and R West (1989). Chapter 12 Decline of Seagrasses. In: Biology of mechanisms. Seagrasses Ed A.W.D. Larkum, AJ McComb, and Problems: Lack of appropriate S.A. Shepherd. Elsevier, Amsterdam. compensatory mechanisms, especially for large-scale dredging. Little available room to manoeuvre. Lack of performance/success indicators. Solution: Equivalent seagrass replacement and possible rocky reef creation. Potential for restoring with fish. Results: Unknown at this time.

Conclusions The challenge is not merely to conserve what is left of our important estuarine fish habitats but, whenever and wherever possible, to repair past damage done and compensate for unavoidable destruction. The opportunities exist now, and fisheries habitat managers need to be entrepre­ neurial in their approach and to broaden their traditional horizons and skills. These estuarine habitats are the source of tangible benefits to the public. They, together with the fisheries they sustain, are a renewable resource of potentially infinite value to the com­ munity. They are a common property resource and the whole community must share the responsiblity for conserving them.

References Pollard, D.A. (1976). Estuaries must be protected. Austral­ ian Fisheries 35(6), 1-5. Pollard, D.A., M.J. Middleton and R.J. Williams (1991). Estuarine Habitat Management Guidelines. NSW Agriculture and Fisheries, Sydney.

Bureau of Resource Sciences Proceedings 187 MANAGING FRESHWATER FISH HABITAT

W. Fulton Inland Fisheries Commission 127 Davey Street Hobart TAS 7000

Issues/Problems What exactly is the problem? There are many factors that may influence fresh­ Is the fish habitat being affected directly or water fish habitat quantity and/or quality, in­ indirect! y? cluding: Is the effect lethal or sub-lethal? water abstraction: • Is the process reversible in the short or long agriculture; term? industry; The ability to positively influence fish populations via their habitat requires knowl­ power generation; edge of the relationships between a fish species impacts on habitat-(direct or indirect): and its habitat and the effects of outside influ­ ences on that habitat. mining; Decisions are invariably made in the ab­ industry; sence of sufficient information. For example forestry--chemicals,physical changes; what is the shortage of a particular fish species really due to? Is it overfishing, habitat degrada­ agriculture--clearing, chemicals; tion, a combination of both, or even over-expec­ power generation-temperature, tation? The latter is a common problem in discharge; recreational fisheries. government-wastedisposal; The present situation is that regular con­ flicts are arising between users of freshwater catchment management; habitat, and resolutions are required immedi­ stream 'improvement'; ately. Unfortunatelythere is always going to be insufficient information on fish habitat require­ fauna translocations. ments. It is nevertheless a distinct disadvantage This list can essentially be viewed as a list in the negotiating process that we are usually of groups to deal with in user-conflict situa­ unable to categorically define the link between tions. Nowadays one should also certainly add fish and habitat and rarely able to define links conservation groups. quantitatively. In trying to look after fish habitat interests Environmental flow assessment method­ in these conflicts, managers are immediately ologies provide some hope for informed input to confronted by lack of information. the habitat allocation process but further refine-

188 Bureau of Resource Sciences Proceedings ment is required. In some Australian States there provision of artificial substratesfor whitebait is still no legal requirement or basis for consid­ spawning; eration of an environmental allocation in any • construction of artificial stream barriers to case. prevent migration of predatory fish to con­ serve particular species; • controlled stocking forrecreational species; Management options fish passes to allow access to additional Amelioration habitat; There are certain categories of actions that could • best be described as amelioration. These are water level management to promote usually designed to limit certain influences macrophyte growth. following laboratory and field evaluation of particular processes. Guidelines or management Conservation plans should be developed, preferably with the Would a reserve actually help a certain species? involvement of those responsible for the This raises a series of questions as well as ac­ problems. tions. Examples in freshwater in Tasmania: Again, knowledge of the relationship be­ pesticide use in agriculture and forestry­ tween the species and its habitat is essential. develop guidelines for safe use; Should we be looking at single species or at general habitat conservation? What are we try­ • toxicity studies on paper mill effluents­ ing to conserve? provide feedback to treatment plant design; There may be a need to conserve particular instream flow evaluation-develop elements of habitat for certain life history stages environmental flow parameters; of a species: effectsof forestryoperations on freshwater­ spawning habitat: provide feedback to Forest Practices Code; estuarine marshes for whitebait; • storage discharge problems-develop instream snags for river blackfish; operational guidelines for power stations; • nursery habitat: lakewater level fluctuations-evaluate conditions to achieve balance. lake, river and estuarine marshes for some species; marginal vegetation in lakes; Enhancement Can the present habitat or fish numbers them­ • adult habitat. selves be supplemented in some way? Ideally Obviously there is a lower limit to the area this requires detailed knowledge of the relation­ of habitat that must be conserved for various ship between a fish species and its habitat. If this reasons. For example, in terms of security a is known then how can this knowledge be used? small reserve may only serve to focus attention. Processes usually involve manipulation of a par­ ticular part of the habitat. In terms of effectiveness is habitat conser­ vation the answer? Examples in freshwaterin Tasmania: • for a migratory species; spawning habitat enhancement or control for trout; for an overexploited species.

Bureau of Resource Sciences Proceed_ings 189 Detailed knowledge of the life history of the species is therefore essential. In conclusion, there are no general solu­ tions. There are no universal critical factors; they vary with species, with time and with area. Each individual case will require a specific course of action which must include a monitor­ ing program. The level of resources available will not influence the best option but, in practice they certainly influence the effectiveness of any action.

Education Community consultation and education is the most powerful means of effecting change al­ though it can take time. It also requires consid­ erable effort on behalf of managers to ensure that these groups are well supplied with infor­ mation. It is also the best way of influencing politicians. A good recent example is the Landcare program through which many community groups have obtained funding to rehabilitate certain lands. In Tasmania this has been widely used to fund willow removal and re-vegetation of stream banks. This area is the most powe1ful means of bringing about the climate for habitat protec­ tion. However, it requires good information generated through specific applied research.

190 Bureau of Resource Sciences Proceedings DISCUSSION OF SESSION 7

Recorded by D.A. Pollard Fisheries Research Institute PO Box 21 CronullaNSW 2230

Questions were first addressed to individual Bob O'Boyle replied that the proponent panellists, and then followed by more general comes with a package which includes his discussion. proposal, and what he feels he has to do under the legislation. It comes to the notice of Fisheries, Following Bob O' Boyle's panel and basically within the first step the presentation, Chairperson Barbara Richardson Governmentexamines it, and if it appears that asked for the discussion to consider pollution there will be a major impact, then it is opened to property rights, and what impacts these may a public hearing process. In short, only the have on policies and management options for proponent and Government are involved until a fish habitats. decision is made as to whether there will be a Murray MacDonald opened the discussion major or a minor impact. Clearly, with 2000 by commenting that the legislation referred to proposals coming in a year, that could mean a by Bob O 'Boyle, and on which it was presumed lot of public hearings. So, what are really being that all these strategies for management were concentrated on are the major impacts, and if based, was in fact Fisheries legislation and that the Minister for Fisheries says it is a major the definition of habitat used was based on the impact, he establishes a three to five or seven, value of that habitat to fisheries production. He member panel. Generally it is at that level that asked whether there is any other legislation in you find a good cross section of the people that Canada which defines the value of habitat and would be involved in the issue. the management of habitat in terms other than Barbara Richardson, in inviting some fisheries, and how it interacts with the Fisheries questions on Jenny Burchmore' s panel legislation. presentation, believed that the speaker had Bob O'Boyle felt that he was not close demonstrated very well the position Fisheries enough to the issue to make an authoritative Habitat Managers are put in quite frequentlyin comment. He knew that the Department of En­ terms of serious decision making and vironment had a lot of air pollution control negotiating. regulations, but did not know whether all habitat The sorts of information they may have are legislation was specificallyunder the Fisheries often insufficient, but nevertheless we've got to Act. move forward; we have to take opportunities Peter Young asked where industries and that come up and learn from them so that we other stakeholders would get involved in the progressively develop and improve policies for process of decision making. protecting and managing our habitats.

Bureau of Resource Sciences Proceedings 191 Julian Pepperell told Jenny Burchmore that some of the priority things done? He was sure he was surprised with the lack of legislation to we know the key factors in freshwaters, any­ protect seagrasses and mangroves. This is all the way, and we know the key threats. You can go more amazing considering that NSW Fisheries down the list-I, 2, 3, 4; dams, riparian vegeta­ can gazette overnight other restrictive regula­ tion, catchments, toxic impacts, whatever they tions on the catching of fish, like bag limits, are. How do we break this cycle every time they closed seasons and so on. build a new dam? Maybe next time in Victoria, which may be 20 years away, we might get them Jenny Burchmoreresponded that there were to put in a fishladder and a multi-level offtake; other agencies which did not believe that regu­ but in the meantime there are 20 dams out there lation to protect vegetated habitats was a Fisher­ that are still causing havoc. How do we actually ies role. NSW Fisheries is now getting new break that cycle? legislation and hopefully this will provide proper protection for some of these areas. The really Wayne Fulton believed that public aware­ difficult thing in getting new legislation de­ ness can be a great tool in the longer term as with signed to protect fish habitat is defining what it litter campaigns, which are a simple means of is you want to protect, what constitutes critical educating people not prepared to let something habitat, and so on. happen. Peter Gehrke refened to Jenny Burchmore 's The way we've probably got to go with this mention of the lack of guidelines for the creation is to motivate organisations, whether they be of compensatory wetlands in Australia. The US angling groups or conservation groups, to push Army Corps of Engineers has guidelines to things in the right direction, i.e. to demand that compensate for habitat damage; for example, these processes take place and that there be when extracting soil from one site for major some coordination for them as well, which is construction projects elsewhere. A comparison something very much lacking. As Bob O'Boyle of fish nurseries found that habitats created said, we should take the lead. There are at least according to Army specifications consistently IO organisations with management responsi­ provided good recruitment to local fisheries. bilities for fresh water in Tasmania, and no one Despite having limitations in Australia, the same is prepared to take the lead in many cases. guidelines could be used to develop our own Someone does have to take the lead, to say this requirements forcompensatory wetlands. is how we do need to go, and to develop some Barbara Richardson agreed that this was sort of strategy. We are short of time and short the sort of approach needed now. We have to go of resources, but we can get some of the public out and do something based on our present to demand of the Ministers that something be knowledge. We may make mistakes along the done, and get someone to coordinate these is­ way, but if we can build a reasonable experi­ sues-that is one way we can move forward. mental design, it will give us directions for the Barbara Richardson suggested that one of future, or information on how to do it better in the very important matters Wayne Fulton had the future. raised was about dealing with government agen­ John Koehn commented on Wayne Fulton's cies and shifting their attitude. What we should presentation that the outline presented for Tas­ be aiming at is to make them think differently. mania was basically how things operate as far as External pressure in the community can be priorities go in Victoria as well. You end up harnessed to help change attitudes, and strategic followingup projects or files or whatever comes planning processes in Fisheries agencies can up. How do we get around that, given the lack of also reflectthe importance of this component in resources, and try to set our own agendas to get fisheries management.

192 Bureau of Resource Sciences Proceedings Peter Jackson again emphasised the im­ Rob Lewis was interested in Bob O 'Boyle's portance of data. In Queensland, where Water reference to transferable pollution property Resources is listening to Fisheries, they will rights. When transferringrights, does that take build fishways. In fact there is legislation to into account the differentor similar capacities of force people to build fishways; but there is not differentwater masses, or can they just be trans­ yet a complete data set to build proper fishways, ferred across just any water masses; or do you and this can lead to enormous problems. At the approach it on the irrigated watershed manage­ moment a million dollars is being spent on two ment strategy? fishways, and as Martin Mallen-Cooper will Bob O'Boyle replied that he had added that tell, it is not certain whether one of those as a thought for discussion, but in fact they were fishways will work or not. So we have the not using those rights now at all. He knew that goodwill there, we've got the cooperation, and it had been used in other fields, certainly in air we have some data, but if we do the wrong thing pollution, and maybe it is something that could we can set everything back twenty years. We be considered. need to have the data as well as knowing what the threats are. Barbara Richardson commented to Rob Lewis that NSW is having to face that now, Wayne Fulton agreed with Peter Jackson. because the NSW EPA has new legislation In Tasmania there is no legislation for fishways, which provides for pollution rights; and the or even the right to talk about water allocations. Fisheries agency has to develop a response to There is no legislation to cover that at the that as managers. But it is one of those issues on moment. So they have just had to muscle their which there isn't much information at all. How­ way in to be able to debate water allocations ever, some information is being collected on with some of those other groups without any some of the problems with bioaccumulative legislative backing at all. materials that have been licensed for discharge Mick Olsen wanted to know whether the and give cause for concern.Other components, emphasis in Tasmania is now on the native fish such as nutrients, are seen as potentially suitable rather than trout. for management by property rights at this point in time. Priority is not being directed towards Wayne Fulton pointed out that this is not those problem chemicals that are persistent at the case. There has been a lot of work done in this stage. recent years on the native fish, but there are still very strong recreational fisheries based on the Karen Edyvane responded to Barbara salmonids, and a need to balance those inter­ Richardson's plea for tools of management by ests. Certain elements of the public, if they had refocussing the debate on to ecological model­ their way, would go even more towards the ling, which, in common with Bob O'Boyle, is salmonid side. However, it is the view of the assuming priority in her thinking. That is, that Inland Fisheries Commission that we need the when you are looking for tools of management, balance without that being necessarily the view particularly at a regional level in an ecosystem, of the wider public. it is of the utmost importance to model ecosys­ tem responses. Australia certainly has a number Chairperson Barbara Richardson sug­ of initiatives underway at the moment, and she gested that, as this was the last session before invited Norm Hall to comment on some of the the General Discussion, the focus should now initiatives in ecosystem modelling and the role be on what information managers needed in it can play, not only as a management tool but order to manage and make decisions to im­ also in directing research through concentrating prove Fish Habitat Management. on processes.

Bureau of Resource Sciences Proceedings 193 Norm Hall responded first of all with some Nutrients flowing into Cockburn Sound, background. south of Perth, had resulted in the excessive growth of epiphytes on seagrass leaves, causing The problem of effluent disposal for the the death of the seagrass through the effects of northern Perth metropolitan region is growing. shading. A similar impact had been seen at We have an increasing population. Current dis­ Princess Royal Harbour near Albany in the posal techniques involve secondary treatment, south-west of the State. In both cases seagrasses followed by piping the waste water into Marmion had been lost. The EPA's principal concernfor lagoon, a fairly narrow coastal lagoon bounded the Marmion lagoon was that the enhanced by an offshore reef, where the average depth of levels of nutrients might result in the loss of water is about I O metres. While it is considered seagrass, with an associated impact on the fish that the flushing time of the lagoon is of the order communities of the area. Further outfalls are of about I to 2 days in the region of interest, there also planned to cater for the growth of the city. is concern that the nutrients released into the The cumulative impact of the nutrient added to lagoon from the outfall may simply slosh up and coastal waters by these additional planned down along the coast, rather than exchanging and outfalls must also be assessed. mixing with oceanic water from outside the bounding reef. Initial proposals to study the physical, chemical, and biological processes operating Some years ago, the Western Australian within the Marmion lagoon, in the vicinity of the Water Authority constructed the first outfall Beenyup outfall, lacked integration and appeared within the Marmion lagoon. Subsequently, a excessively expensive. The Water Authority marine park was established within the same decided that the first thing to do was to bring in region. The Environmental Protection Author­ a modelling team, and to run a workshop in ity, EPA, approved the initial outfall, and agreed order to determine the features and processes to a subsequent increase in the volume of waste that required study. It was hoped that this would water to be discharged, conditional on the Water result in a more cost-effective study. Authority establishing that the impact of the increased nutrient load would be acceptable. Of Professor Carl Walters, from the Univer­ concernare not only health, and aesthetic quali­ sity of British Columbia, was invited to run such ties, but also the potential changes that might a workshop. This was held at Perth in December occur within the plant and animal communities. 1991. During the workshop, a garotropic model was set up to describe the physical and chemical The EPA required the Water Authority to aspects of the system. Previous studies had assess the assimilative capacity of the northern suggested that water movement within the sys­ metropolitan waters. The Water Authority faced tem was wind driven. Baroclinic, or tempera­ the need to replicate the pipeline into the lagoon ture and density related, effects were considered (or the northern suburbs would be awash with of lesser importance. Following on from the sewage), and to increase the flow of effluent. The workshop, John Hunter, from CSIRO at Hobart, EPA had constrained the total amount of nutri­ has extended and improved the model of the ents that might be released, and projected in­ physical process. creases in effluent from the region suggested that by 1995 the nutrient load would reach the EPA After calculating the movement of water specified upper limit. It was therefore urgent that within the system, the chemical processes were a study be undertaken to a�sess the assimilative calculated. Then, with an understanding of the capacity of the lagoon, in order to determine concentration of chemicals throughout the sys­ whether further increases in the nutrient load tem, the processes of primary production were might be permitted, or whether alternative dis­ examined. Finally, components were added to posal methods might need to be considered. the model to describe some aspects of secondary

194 Bureau of Resource Sciences Proceedings production, by including filter feeders, goal, and appears to be working well in both detritivores, and grazers. Little informationwas focussing the researchers' minds on the impact directly available formany of the parameters of nutrient enrichment within Marmion lagoon required within the model for the seagrasses, and in using their understanding to predict the macro algae, and epiphytes within the Marmion possible changes that might occur. It should be lagoon, so values were selected fromthe litera­ regarded, however, as only the first step in an ture. A detailed understanding of the processes ongoing research effort to understand the proc­ of growth and mortality of the grazers, filter esses operating within this system. The system feeders, and detritivores was completely lack­ is now the subject of a very intensive study ing, and subjective estimates were supplied for which is expected to terminate in 1995. the parameters required to describe these There is also a very successful plan in place processes. for control of oil spills along the W .A. coast. By The workshop was successful in bringing identifying the resources at risk, and with a together available data, and producing discus­ broad understanding of the physical oceanogra­ sion and interaction between the various groups phy and the biological systems concerned, a involved in the study. While each group is still plan to handle oil spills at various locations was in competition for the available funds, there is formulated. The plan has been tested on several now considerable interaction between the vari­ occasions and appears to work well, although its ous studies that are proceeding. The original effectiveness in protecting the environment has model is being modified and extended, but pro­ yet to be tested by a major oil spill. vides a framework and basis for all the separate Barbara Richardson then displayed (on studies. It focuses the work being undertaken, overhead) the following suggested list entitled and forces the integration and critical assess­ "Data Needs". ment of the information collected. The resulting model is intended to be general in nature, with • Habitat information base-what's there and the facility for it to be applied to other coastal what's happening to it? areas by changing the description ofbathymetry, Data on habitat utilisation: outfalls, and habitat. critical habitats a priority When the original study began, it was thought that little information was available. In juxtaposition of habitats and interaction fact, when the modelling process began, and critical links between habitats data from earlier studies were collected, a con­ siderable volume of information smfaced.These species interaction and by-catch effects data are now being brought together within a How do we 'value' habitats? Geographical Information System. Impacts of harvesting activities: In summary, the approach has been effec­ tive in bringing available information together, species catch data to include in a form readily accessible to managers and environmental data scientists. A modelling frameworkwas used to data on impacts of gear type and integrate the available data, and assisted in the operation on habitats identification of areas where inadequate knowl­ edge existed. Predictions from the model are • Effectiveness of protected areas being made and tested against observations from Collaborative research-multi-discipli­ the real system. The process of modelling has nary/ strategic vs tactical resulted in the interaction of the researchers involved and the establishment of a common Monitoring design and data source

Bureau of Resource Sciences Proceedings 195 Assessment of other human activities Long-term data sets In the discussion which followed, Jenny Burchmore stressed the importance of habitat mapping and inventory to management, and the need for it to be repeated and continued. Sandy Morrison further underlined the im­ portance of monitoring the effects of anything which is done e.g. fish ladder construction. Such feedback is a vital part of the learning experi­ ence from case studies. Jenny Burchmore agreed, but with the res­ ervation that monitoring is not enough. In the event that an undesirable impact is revealed by monitoring, the required management strate­ gies need to be developed. George Paras wanted to place more empha­ sis on amelioration. Alternative strategies of demand management are needed e.g. for reduc­ ing water use. We should be looking towards the long term and applying what is already known about impacts, rather than accepting the status q110 as being good enough. Hugh Cross urged the need for more of a vision, through which to target the decision makers, and encapsulated the three major ob­ structions demonstrated from Jenny Burchmore's case examples as legislation, final decision makers and the lack of information. Barbara Richardson challenged the group on how to set that vision. Murray MacDonald believed that the vi­ sion would be set by strategic planning and informed community debate - a strategic system framework, involving the assessment of im­ pacts of all other types of human activity. In closing the session, Barbara Richardson urged participants to consider the issues of man­ agement through amelioration, enhancement and conservation and have their thoughts ready for the final discussion.

196 Bureau of Resource Sciences Proceedings GENERAL DISCUSSION

Session Chairperson: P.C. Young Session Panellists: R.K. Lewis R.K.Gehrke B.E. Pierce C.M. Macdonald R. Reichelt B.A. Richardson Rapporteur: P.R. Last 198 Bureau of Resource Sciences Proceedings GENERAL DISCUSSION

Chairperson: P.C. Young Recorded by P.R. Last CS/RO Division of Fisheries GPO Box 1538 Hobart TAS 7001

Chairperson's summary The 4 pertinent issues became: By way of a brief review of the proceedings of 1) Who is going to control the use between this Workshop over the past few days, I will conflicting users? take five minutes to identify a few of the critical 2) How do we minimise the effects of con­ issues that emerged as I saw them and then ask flicting use on habitat? each of the Session Chairs to briefly review the issues for a few minutes. I will then seek to 3) The need to identify how these effects on draw the Workshop together to attempt to habitat affectfisheries. synthesise a cogent view of the topic 4) To do l - 3 we need to develop appropriate "Sustainable Fisheries through Sustaining Fish research and monitoring strategies to incor­ Habitat". porate multiple use so that: We started yesterday with an illuminating (a) decision-makers can develop planning keynote address by Stan Moberly who clearly strategies; and identified a number of critical issues in America. These broke down into the need: (b) the data are there for scientific advice. l) forscientists to inform users and decision­ Turning to the relationship between organ­ makers of the value of habitat; isms and environment, we were stimulated by the concept that although we really know very 2) to develop better administrative little about the functioning of habitats, we are arrangements for managing habitats that making sweeping announcements of their value are impacted by cross-state or even cross­ and, following that, have incorporated strate­ country activities; and gies to modify habitats by engineering and 3) for scientists to have a key role in bringing bioremediation. It became clear during the dis­ the conflicting resource uses together for cussion that although we are modifying habitat strategic planning. to produce the "ideal climax", there appeared little agreement as to what was the "ideal cli­ Following Stan Moberly's address, we max" nor if we were sure about how to achieve examined a manager's view of fish habitats. it. During this session the central theme that emerged was that there were competing uses of Turningto the organism/environmental re­ the ecosystem many of which will impact on lationships, we had some problems defining key habitats and fisheries. factors to fishes. We were fairly sure about

Bureau of Resource Sciences Proceedings 199 freshwater where the notion of limited and criti­ broad-based refugia from consumptive use, but cal factors was suggested to develop the con­ that an alternative methodology would be to cepts of ecophysiological controls and critical seek to develop the concept of value-adding to use of habitat. However, as we moved farther habitat use in its broadest sense. This again towards the marine area the precise role of emphasised the importance of communication, critical habitat became clouded. We identified institutional refmm, and managing strategically that habitat is important but don't yet have a forall users. really good definition of the importance. We We then turnedto this concept of manage­ then need to better define our goals. As scien­ ment in terms of ameliorating effects, enhanc­ tists we want to know more, but as managers we ing and conserving habitats. need to be ready to summarise our present knowledge for guidelines. We heard of the approach to conserving habitats by defining the habitats as functional We must determine what is the important units, using explanatory models to understand scale for defining and protecting habitat, and the ways that proposed activities may impact on although we don't know enough, we must pro­ them, and the need for appropriate regulation duce a reductionist view. This will be enhanced and data collecting limited to decision support by the role of the modeller who will help us to systems. There may be some benefit in consid­ define what are the critical elements still un­ ering the purchase of "pollution rights". known about the processes to sustain this mini­ mum necessary knowledge. Amelioration and enhancement of habitats is more difficult. We lack the know ledge of how Overall, by the end of the day we come back to restore habitats, and at this stage are preparing to the issue that we already know enough about experiments to work out how to do it. In view of some habitats to be at the stage where we must this, what is the real compensation for habitat persuade people to understand what we know destruction? How are we going to develop the and to share the conclusions. This might be information required to improve habitats and helped by linkages between professional socie­ ameliorate effects? ties such as the Institution of Engineers or by other initiatives such as a "Status of the Aquatic Habitats" report. Session Chairpersons' summaries Day 2 started off with the impacts of human activities on habitat and fisheries and discov­ Andrew Staniford, deputising for Russell ered that most of the things we summise about Reichelt, commenced with a sun;imary of Ses­ the relationship of habitat and fisheries are based sion 6 which covered the alternative uses of on inferences rather than experiments. We were aquatic habitats. Two proposals were put for­ treated to the resulrs of a long term experience ward: a regulatory approach based on marine which did investigate these relationships. How­ parks or marine development zones as a method ever, because of the cost in dollars and time, it of managing the marine ecosystem; and a value­ was suggested that perhaps we should now take added approach which tries to identify the extra our best guesses and actively seek to insert them value that can be achieved by changing the into the decision-making process. allocation of the resource between the compet­ ing users, as well as by changing their levels of We established that it was important to activity. He stressed that the two approaches are identify the activities which cause change that closely linked. Together they form important impacts on habitats critical to fish communities. tools in establishing priorities for strategic plan­ When looking at the alternative uses of ning and dete1mining which areas are important habitat, we heard that we may need to set _up for certain activities. The main advantages of an

200 Bureau of Resource Sciences Proceedings economic approach are in providing some sort less well understood), he feltthat this viewpoint of measurable, objective criteria forcomparing had been reversed during this workshop. Debate uses, and assessing how changes in the way a focussed on the need to supply information resource is used will affectthe community. quickly to address the present need for habitat amelioration, as against the more traditional Murray MacDonald, in summarizing Ses­ research response which was seen as causing sion 5 on the impact of human activities on only more delays beforeproviding "answers". habitat and fisheries, feltthat the discussion had Gaps between managers and researchers need to focussedon two major issues. Firstly, with few be filled to provide some urgency of response to exceptions (ie. in freshwaterand the most acces­ habitat issues. sible environments where the best information is available), evidence suggests that linkages are A triage response to avoid time-wasting circumstantial rather than proven by cause and was proposed with a line of ascending priority effect type evidence. Secondly, the role of sci­ from habitats that don't need any real suste­ entists in getting the message across regarding nance other than protection, through those that the importance of habitats needs to change. The need some formof active sustenance, to those traditional role of scientists, in conducting re­ that require totally rebuilding. Model driven search and monitoring type studies to provide research, which feeds the best available infor­ detailed information and expert advice on habi­ mation to managers but also highlights the knowl­ tat conservation and management, is still a le­ edge gaps for researchers, was preferred to gitimate and very important role but we have to piecemeal and fragmentary data fed intermit­ broaden our view of our roles and start thinking tently to managers. of ourselves also as purveyors of informationin Peter Gehrke believed that this last ap­ a much more simplified form. proach had led to potential problems in Aus­ Bryan Pierce then provided his perspective tralia because of a tendency to concentrate on on Session 4 which dealt with the key variables system ecology or ecological questions without, and broad-based issues that affect organisms in many cases, evaluating details of the proc­ and environmental relationships. He concluded esses driving the systems. "By ignoring some of that habitats were only unimportant in the the finer points of how the processes work we deepwater/pelagic zone, and that inshore the run the risk of trying to run before we can era w1 priorities diminish progressively from inland when it comes to managing habitats - we end up through to coastal habitats. A model of the getting lost in trying to repair and maintain their adaptive management process using the key virginity". A coordinated modelling effortmust factors was seen to be a "n-dimensional head­ be established to provide some form of expert ache" because we cannot even determine gen­ system that can advise managers and at the same eral key factors. An educational role was also time refine the hypotheses needed to direct identified as being critically important. research. He concluded by raising the issue of the effects of global climate change on fish Peter Gehrke summarized the results of habitat. Session 3 covering case studies of organisms and environmental relationships, during which A manager's view of fish habitat (Session a number of the processes for sustaining fish 2) was then summarized by Rob Lewis. He habitat were addressed. While he had originally believed that the consensus view is that we want believed that our knowledge of fishhabitat was to see the habitat managed successfully and we in some way proportional to the number of all want to contribute to that outcome. Session 2 people researching each of the various habitats had identifieda need to address the issues, such (ie. that estuarine and coastal systems had been as competing use, impacts and demands, which worked to death while freshwaterhabitats were cannot be handled solely by fisheries interests.

Bureau of Resource Sciences Proceedings 201 A key role for ASFB was also identifieddespite modelling as a strategy for focusing on our differing views on specific issues within the information needs, setting of research priorities, membership. This group, with the expertise and and in the design of monitoring programs. She the will, was considered to be capable of taking referred to a problem identified by Jenny a lead (ie. harnessing, coordinating, and pro­ Burchmore relating to our influence in the deci­ moting these actions). There is a need to coordi­ sion-making process, and felt that many nate the scientificcomponent, communication, stakeholders affect these decisions and the So­ and the planning and application stages with ciety needs to play a more active role. appropriate strategies at different levels fordif­ A list of the major issues identified by an ferent audiences. Finally, he observed a wide­ informal working group the evening beforewas spread emotional commitment to prevent further shown (Tables 1 and 2). Barbara Richardson habitat decline or at least replacement, and to pointed out that the list was largely unstructured look beyond maintenance alone and consider but contained many issues for general consid­ habitat amelioration. eration. She reiterated the sentiments of other BeforeBarbara Richardson's summary of participants that although many of the habitat Session 7 on the amelioration, enhancement and issues have been discussed for 20 years we conservation issues of management, Peter Young haven't achieved much to date. She feltthat a suggested the need forfocussing the subsequent cuITentsituation statement outlining the issues, discussion and invited Barbara Richardson to and our views concerningpossible action plans, present additional overheads considering the should be included in the proceedings. This focalissues. statement should also highlight the importance of fish habitat management. She outlined some Barbara Richardson commenced by point­ focal questions that might be considered during ing out that much of our effort is directed to­ the drafting process: whether there should be wards firefighting, largely unproductive, and more integration between traditional fisheries needs to be focussed on a strategic planning management and other ecosystem users; the process. She acknowledged that the Society had need formore research and the identification of the resources and the commitment and proposed issues considering data requirements; extract­ a more structured visionary approach to be ing from managers around the country their outlined in the workshop proceedings. Within perspective of key issues and pressures; and the the planning process, she felt that we need a need to focus scientists' priorities forresearch clear definition of goals, to consider all the and management. possible strategies available, to develop per­ formance indicators, and most importantly to She suggested producing a synthesis of "look at where we are going and see if we are these viewpoints but acknowledged that doing actually getting there". so might not be realistic within the time remain­ ing. The issue was left open for the chairperson She believed that the strategies identified to decide but she feltthat an outline of cuITent during the workshop had merit, highlighting the key issues could be used as a yardstick in the entrepreneurial experiences of some partici­ future. This would also highlight the next step, pants. As an example of integration, she refeITed particularly if drafted as a situation and action to Bob O'Boyle's experiences in Canada. She statement, which she suggested might need to proposed an adaptive management strategy and be constructed by a drafting committee. drew attention to several other issues discussed: identification and consideration of problems; Other important issues included the the inadequacy of some existing legislation; the desirability of having a "state of fish habitats" possible inadequacy of our ,information base assessment document with annual upgrades. and future data needs; and the importance of This document, possibly enlisting broader

202 Bureau of Resource Sciences Proceedings community help, would complement impending then Standing Committee on Fisheries. He sug­ State legislation on environmental reporting. gested that the Society should investigate the She recommended the formation of an ASFB activities of and provide input into such com­ sub-committee to meet annually with the mittees. He challenged the perception that there responsibility of implementing workshop was little scientific communication with the outcomes and reviewing the progress of fish fishing industry or the general public. He be­ habitat management. She proposed the lieved that communication ranged from quite establishment of an annual newsletter covering good to exceptional and that we should be fish habitat issues and forming closer links encouraged with our efforts ratherthan discour­ between ASFB and governmentagencies. She aged. He advocated greater communication be­ felt the Society could take a leading tween the States and referred to the example communication role by convening a national cited earlier by Jenny Burchmore of the oil workshop including representatives from all pollution atlas. groups whose activities impact on fisheries Peter Young commented that the FPC and resources together with conservation groups affiliates do consider national issues and the and government agencies. Society members CSIRO's Division of Fisheries provides the could also create an awareness of fish habitat by secretariat forthat committee. publishing in popular scientific journalssuch as "Geo" and "Search". A news release could be Ross Winstanley supported this view, stat­ produced fromthis workshop drawing attention ing that whereas the FPC addressed a narrow to the major issues identified. fieldof issues 15 years ago, the committee now displayed a changing emphasis, focusing more Peter Young, however, cautioned that it is on the habitat and environmental aspects of easy to set work up but it is sometimes harder to fisheries management. He commented on Peter find someone to do it. He also pointed out that Young's prediction that ANZFAC may estab­ fisheries managers are now recognising the lish a sub-committee to investigate fishhabitat importance of habitat and suggested that issues in relation to fisheries by stating that it ANZFAC (formerly Standing Committee on was long overdue. Fisheries) may form a committee to monitor habitat in the near future. He then opened the Duncan Leadbitterreiterated the point about session for question time and invited the presi­ the type of information needed and the need to dent, Julian Pepperell, to suggest where we approach the relevant groups for input. In his could progress after the discussion. capacity as a member of NFIC's environment committee, he claimed that an informal ap­ proach from ASFB to collaborate on habitat Discussion issues would be welcomed. He also offered to coordinate a small working group to draft guide­ Don Hancock was concernedabout the general lines for environmental impact assessments. viewpoint that "not much had been done". He feltthat a great deal had been done but probably Peter Young then raised the issue of an not quickly enough. A great deal of work was inventory of critical habitat. Very good exam­ being done independently by individual States ples of this kind of data have been collected in but there seems to be no national forumfor the the USA and some other countries. He sought discussion of technical issues, and most envi­ the views of the meeting and raised a number of ronmental committees are forced to work to related questions: should an inventory be con­ administrative guidelines. As an example, he structed; if so, on a national or State by State referred to his experiences as a member of the basis; what information is available and is it Fisheries Pollution Committee (FPC) of the archival; should we approach Environmental

Bureau of Resource Sciences Proceedings 203 Resources Information Network (ERIN) or Norm Hall, readdressing the issue of an National Resources InformationCentre (NRIC) inventory, stated that to convince decision-mak­ to get it onto a Geographical Information ers you need performance measures to gauge the System (GIS)? effectiveness of habitat protection strategies. He commented that most bureaucracies set up Murray MacDonald felt that the Society committees when a problem arises whereas ought to be taking a higher profilein bringing researchers traditionally collect more data to these issues beforethe general public, as well as study the problem. Now, both groups see the the legislators and managers. He suggested that need to develop models of these systems to help part of the costs of convening a conferenceand identify suitable management options. As a con­ making statements about the state of the marine sequence, the various bodies responsible for environment could be met externallyby dove­ managing aquatic habitats will require more tailing the Society's interest with current na­ integrated types of studies with a focus on tional initiatives. Two such initiatives are the modelling the underlying process. Such a focus development of a national "state of the marine will certainly help bring the data together. How­ environment" report process and the develop­ ever, he cautioned that the modelling exercise is ment of a national conservation strategy. The not a panacea and does have serious limitations "Ocean Rescue 2000" scheme was suggested in the present climate where data sets are incom­ as a possible funding source and co-convenor plete. He also alluded to problems of communi­ of a conference to discuss these issues. cation and bringing regulatory bodies together. Roland Pitcher proposed an alternativecost­ Peter Young took up this point and raised effectivecommunication method involving the the issue of integrating catch and management, ABC's"Survival" program. He outlined possi­ the effectivenessof which is entirely dependent ble contents of episodes and suggested that the on the good will of the various regulatory bodies ASFB president contact the producers of"Sur­ involved. In these instances, the modelling ap­ vival" to canvas the issue. proach acts "as a facilitator to get pig-headed Stewart Frusher, giving the example of his people to become less pig-headed". own work on rock lobster, expressed concernat Dianne Hughes commented on the size of not be able to view changes to habitat beyond goals suggested, intimating that they were prob­ diving depths (ie deeper than 30 m). He alluded ably overambitious. She felt, referring to issues to the high cost factor of studying habitat at raised by Barbara Richardson, that it might be greater depths. His sentiments were shared by more sensible to set smaller, more achievable Peter Young. goals. David Smith strongly supported the need John Koehn agreed with most of the ideas to prepare a current situation report together that Barbara Richardson had put forward and with a separate document on the state of fish believed that the workshop should take Stan habitat. He felt that these issues should be Moberly's advice and be pro-active. ASFB, handled by a resurrected habitat sub-committee being immune fromsome of the problems con­ because the Workshop forum was too large and frontingus within our various agencies, could unwieldy. Peter Young supported these views become Australia's leading voice. He stated that referring to the highly respected Endangered workshops should have a bottom line, setting Fish sub-committee which is the major source out priority needs and areas. While uncertain of advice in this area to the regulators of rel­ about its worth formarine habitats, he believed evant fisheries. He stressed that the influenceof it possible for freshwater and wished to see ASFB shouldn't be underestimated. action taken at this workshop.

204 Bureau of Resource Sciences Proceedings Martine Kenlock followed up the sugges­ The role of this new sub-committee would be tion by Roland Pitcher by offering to contact the similar to that of the Endangered Fish Sub­ producer of"Survival" on behalf of the Society. committee which has an extremely important advisory role. Peter Young conceded that it was impossi­ ble to progress further given the size of the Peter Young then closed the session and forum and invited Julian Pepperell, as president asked Stan Moberly to deliver his summary. of ASFB, to give his perspective on where the Society should go fromhere. Table 1. Habitat management Present situation-Analysis President's summary What do we need to achieve? Julian Pepperell agreed with the panellists' By - Amelioration -+ site/system view of the Society's role and endorsed most of specific their ideas, stressing the need to be independ­ ent. He addressed the issue of conflictinginter­ Enhancement -+ site specific ests, which sometimes occurs between the - Conservation -+ package of Society and the Institutional roles of members, measures to but quoted Stan Moberly' s experiences with the apply to all American Fisheries Society which has been waters very successful in providing an independent voice in the USA. He strongly endorsed re­ • How will we know if it's working? establishment of the habitat sub-committee and • Data needs invited Barbara Richardson, as the newly ap­ pointed chairperson, to appoint additional mem­ • How can we improve the protection and bers. He agreed with most, if not all, of the management of fishhabitat? action plan provided by Barbara Richardson in Tables 1 and 2 and suggested that a copy should be made available to members at this workshop. Table 2. Improving fishhabitat protection and He felt that the Society had the expertise to management provide information on a national scale with • Agency profile and effectiveness members needing to think more broadly be­ yond their own regional boundaries. The ap­ • Researchers and managers promote aware­ proaches of the National Marine Fisheries ness and information Service and the American Fisheries Society, in • Collaborative programs with other govern­ producing a document on the state of aquatic ment agencies or disciplines habitats, were used as role models. He sug­ gested coordinating with other similar interest • Community programs-involvement groups, such as "Ocean Watch 2000", but with­ • Media out compromising the Society's position. The Society's major goal should be to assess the • ASFB plight of habitat over the past 200 years of European settlement in order to warndecision­ makers of possible dangers in the next 200 years. He stated that ASFB should be in an ideal position to provide advice on key issues to any related sub-committee established by ANZFAC.

Bureau of Resource Sciences Proceedings 205 206 Bureau of Resource Sciences Proceedings a. ::> c., z -:E :E ::> en 208 Bureau of Resource Sciences Proceedings SUMMING UP

S.J. Moberly NorthwestMarine Technology Inc. POBox99488 Seattle WA 98199-0488

My observations over the past two days have Sewage isn't good forsea life nor people. lead me to list several remarks and statements I We know that the catchment, the rivers, the heard. We have "wrung our hands" and "ground estuaries and the nearshore marine waters our teeth" over the impacts of habitat loss and are important to fish. there seems to be much we do not know or understand about aquatic ecosystems and how . Man's activities don't "create" fisheries they interact. But, during our discussions these habitat-mostly man's activities destroy or past two days, there were several points worthy compromise habitat. of note. Man's activities don't cause fishpopulations In no special order, some of the things I to increase-it is mostly the opposite. noted are: We know that the general trend of most fish Aquatic habitat is valuable; it is not plentiful, populations is downward; we just don't it is fragileand it is disappearing rapidly. fully understand politically how to reverse the trend. There are too many people. We know that if you drag bottom trawls Most people are ignorant about the value of . over the sea bed you will kill the plants and aquatic habitat. animals that live there. Change happens and the rate of change It is a mistaken concept that politicians often outstrips our ability to learn, . lead. understand and react. It is a mistaken assumption that "top deci­ Development will continue to destroy sion makers" make good decisions and that aquatic habitat. it comes naturally. Some habitats are beyond help and we . Top decision makers make good decisions should "tend to the crown jewels and the . with good information. walking wounded". Top decision makers need timely informa­ Fish and the other "critters" need a place to . tion. live and our understanding about how ecosystem(s) function must be more . Politicians move with consensus . complete. We should share our knowledge. our work . Covering aquatic habitat with dredge mate- is fun, its exciting, and we should educate rial spoils the habitat. our citizens.

Bureau of Resource Sciences Proceedings 209 We are not good at sharing our knowledge believe fisheries scientists and managers know outside our own circle. what is wrong with the fisheries and how to correct it. We could be better at sharing our knowledge; we must learnhow. There seemed to be consensus that action is better than inaction and that scientists and man­ Others care about aquatic resources and agers are determined to play a role in helping to habitat too. shape Australia's fishing future. I stated in my • We can identify our allies. keynote address, that for a nation to maintain successful fisheries they need: national strate­ We can form partnerships-to teach and to gies, implementation schemes, adequate money, learn; relationships are best when both enforcement, adequate legislation, adequate parties are enhanced. assessment, and periodic audit to measure Not everyone will share our values or our progress. You know Australia's fisheries are a points of view. valuable, renewable national asset. There is consensus that success is better guaranteed with Sometimes the best solution isn't possible. your attention, your views, your energy, and Sometimes the best solution is the one that your knowledge. There is no group more knowl­ makes everyone equally unhappy. edgeable about the fishery resources of the nation than yours. It is easier to "walk backwards into the future;" it is more difficult to affect the I think important conclusions have been future and implement our visions. reached during this workshop. I feel a determi­ nation by the participants. And I sense that the Ecologically sustainable might have been ASFB will elect to play an even more active role present before man intervened. to have a positive influence on what the future Helping to manage human impacts on holds for this continent's fisheries. If not you; habitat is our most difficult task. who? There is no group more capable of lead­ ing. I sense you are determined to be Australia's The smarter we get the easier the job principal champion for its fishing future and I becomes. applaud you. We need to learn to forgive ourselves for I appreciate very much being invited to our uncertainties and our shortcomings. participate in this workshop. You live in a fun Multiple use is not synonymous with and wonde1ful land and these are important compatible uses. times for fish and fish habitat. Value comes in dollars but it also is measured in the needs, wants, desires and aspirations of people. I am sure I missed some points of what we talked about over these past two days but I believe I captured the essence of what transpired. The inescapable conclusion is that we know a lot about the problems with habitat and what to do about it! And we recognize there is much we do not know or understand. But our lack of understanding is mostly our secret! Australians

210 Bureau of Resource Sciences Proceedings APPENDIXES

Appendix 1. Australia's Threatened Fishes 1992 Listing­ Australian Society for Fish Biology. By P.D. Jackson, J.D. Koehn and R. Wager Appendix 2. Workshop Program Appendix 3. List of Participants 212 Bureau of Resource Sciences Proceedings APPENDIX 1: AUSTRALIA'S THREATENED FISHES 1992 LISTING­ AUSTRALIAN SOCIETY FOR FISH BIOLOGY

P.D. Jackson1 , J.D. Koehn2 and R. Wager1 1 Fisheries Division, Queensland Department of Primary Industries, GPO Box 46, Brisbane OLD 4001 2Freshwater Ecology Section, Department of Conservation and Natural Resources, PO Box 137, Heidelberg VIC 3084

Introduction The Society's decision to hold a "habitat workshop" has provided the opp011unity to for­ Australian fishes were first classified according mally publish an updated listing and to provide to their conservation status by the Australian further specific details on threats. The Threat­ Society for Fish Biology (ASFB) at a Confer­ ened Fishes List was updated by the Committee ence on Australian Threatened Fishes in Mel­ at the time of this 1992 workshop. bourne in August 1985 (Harris 1987). As a result of this Conference, the Society estab­ lished aThreatened Fishes Committee to under­ take an annual review of the conservation status Conservation status classifications listing. The Committee has reviewed the listing The following conservation status classifica­ each year since 1987 and updated listings have tion was adopted by the ASFB at its conference been published in the Society's newsletter.The in 1985 (Harris 1987) and updated at the Soci­ publications of the 1989 listing in Pollard et al. ety's conference in 1989: (1990) and Ingram et al. (1990) comprise the first international publications of the ASFB's Extinct-Taxa which are no longer found conservation status listing andthey include some in the wild or in a domesticated state. information on reasons for decline of some Endangered-Taxa which have suffered a species together with possible management op­ population decline over all or most of their tions. However, an updated listing has not been range, whether the causes of this decline are formally published and no additional informa­ known or not, and which are in danger of tion has been included on the threats to Austral­ extinction in the near future. (Special man­ ian fishes and their habitats since 1990. The lack agement measures required if the taxa are of comprehensive and updated information on to continue to survive). threats to freshwaterfishes is particularly sig­ nificant because one of the recommendations of Vulnerable-Taxa not presently endan­ the Conference in 1985 was that the Committee gered but which are at risk by having small should 'advise on fish conservation matters in­ populations and/or populations which are cluding management of habitats of threatened declining at a rate that would render them species' (Harris 1987). endangered in the near future. (Special

Bureau of Resource Sciences Proceedings 213 management measures required to prevent was noted that the status of the southernbluefin the taxa becoming endangered or extinct). tuna (Thunnus maccoyii) required investiga­ tion. Since 1990 there have been no further Potentially threatened-Taxa which could nominations for marine species and threats to become vulnerable or endangered in the these species are not discussed in this paper. near future because they have a relatively large population in a restricted area; or they have small populations in a few areas; or they have been heavily depleted and are Threats to freshwater fishes continuing to decline; or they are depend­ The exact reasons for the decline of many native ant on specific habitat for survival. (Re­ freshwaterfishes are not well known. However, quire monitoring). many threatening processes are well recognised • Indeterminate-Taxa which are likely to and have been documented and discussed by fall into the Endangered, Vulnerable or many authors (e.g. Koehn and O'Connor 1990a; Potentially Threatened category but for Cadwallader 1978; Wagera nd Jackson in press). which insufficientdata are available to make In general, these threats apply to threatened and an assessment. (Require investigation). non-threatened species alike and although the urgency for attention generally rests with the Restricted-Taxa which are not presently former,such threats continue to cause the de­ in danger but which occur in restricted cline of many species, moving them closer to areas, or which have suffered a long term inclusion on threatened species lists. Being hid­ reduction in distribution and/or abundance den underwater engenders a lack of public un­ and are now uncommon. derstanding of freshwater habitats and • Uncertain status-Taxa whose taxonomy, ecosystems, and hampers recognition of many distribution and/or abundance are uncer­ of these threats. tain but which are suspected of being Re­ The causes of decline of all species listed in stricted. categories considered to contain fish under threat Table 1 shows the 1992 Conservation Sta­ (Endangered, Vulnerable, Potentially Threat­ tus Listing. ened and Indeterminate) were assessed from nominations received or expert opinion sought in relation to each species. Threatsare listed in order of numerical occurrence in Table 3 and Summary of change in details of the threatening processes for each listing since 1985 species are given in Appendix IA. Table 2 shows the numbers of fish classified in The number of threats listed varied be­ each category, each year, since 1985. The total tween species, ranging up to seven. For three number listed has risen from 59 to 72 and species no particular threats were identified(see perhaps more significantly, the number of fishes Murray hardyhead Craterocephalusfluviatilis, listed as endangered has risen from4 in 1985 to swamp galaxias Galaxias parvus and non-para­ 11 in 1992. sitic lamprey Mordacia praecox in Appendix Prior to 1990 no marine species appeared IA). It is recognised that some threats for other on the listing. That year the grey nurse shark species may remain unidentified due to a lack of (Carcharias taurus) (Vulnerable), the black cod knowledge of their biological requirements. The (Epinephelus daemeli i) (PotentiallyThreatenic!d) reasons for the decline of a species may not be and the great white shark (Carcharadon due to one single threat but often the result of a carcharias) (Uncertain Status) were listed and it combination of several factors, and threats may

214 Bureau of Resource Sciences Proceedings not be uniform throughout the species range or can cause a decline in fish populations. As each lifecycle. As well as affecting a fish species, fish species has different habitat requirements, many of the threats also have detrimental effects each habitat variable can pose a differentdegree on other aspects of the freshwaterecosystem. of threat to each species when that attribute is altered. Very rarely do such alterations cause an Detrimental interactions with introduced immediately recognisable decline in fish num­ species were considered to be a threat to 20 of bers (of course toxic spills may), but more often the 26 native species listed, with the mosquitofish they have subtle effectswhich may cause a slow Gambusia holbrooki being implicated in 9 in­ population decline. stances. Gambusia is widespread throughout mainland Australia (McKay 1989), exhibiting lnstream habitat alteration and destruction aggressiveness and wide environmental toler­ due to removal (desnagging, channelisation, ances which enhance its interactions with other excavation, gravel extraction), swamp drain­ species (Lloyd 1989). This species has been age, flooding after dam formation, cattle tram­ linked to the decline of at least 35 species pling, mining, development and forestry overseas, and although the mechanisms for in­ activities contributed to the decline of 16 spe­ teractions with Australian species are not well cies. The removal of riparian vegetation, which understood, they are likely to include competi­ provides shade, foodand organic inputs, habi­ tion for food and space, and predation, particu­ tat, filtration of runoff and bank stability was larly on eggs and fry(Lloyd 1989). Interactions also seen as a major threat (13). In addition to its with brown trout Salmo trutta (7), redfin Perea importance to fish species, riparian vegetation fluviatilis(3), and rainbow trout Oncorhynchus is an essential component of the aquatic ecosys­ mykiss (2), mainly through the process of preda­ tem and its removal has an overall detrimental tion, are major threats to many species, particu­ effect. Sedimentation (fromforestry activities, larly smallerones (such as Galaxias spp.) which roads, developments, mining, agriculture and are often in otherwise relatively natural habitats. catchment erosion) was also seen as a contribut­ The effects of trout and their exclusion of smaller ing factor in habitat degradation in many cases native fish species has previously been docu­ (9). The importance of instream habitat and mented (Tilzey 1976; Fletcher 1979; Jackson riparian vegetation are explored by Koehn and and Williams 1980; Jackson 1981). In three 0 'Connor ( 1990b). instances native fish which have been Changes to water quality (8 cases) included translocated, orin one case have invaded waters changes to temperature due to low level releases outside their natural range, were considered a fromimpoundments, inputs of nutrients and one threat to indigenous species (see Lake Eacham case of toxic inputs due to mining. rainbowfishMelanotaeniaeachamensis, Pedder galaxias Galaxias pedderensis and Mary River Reductions in flooding and the seasonal cod Maccullochella n.sp. in Appendix IA). reversal of streamflow fromirrigation impound­ ments, reduced and regulated flows and reduc­ The over-riding threats causing the decline tions in the water table (particularly affecting of fish species are the destruction and alteration springs) through water extraction were assessed of habitats. These have been listed under a as a threat to seven species. variety of headings. The key habitat variables for freshwater species have been outlined by Four large angling species (see trout cod Koehn (this meeting) and include the amount of Maccullochella macquariensis, Mary River cod water, physical and chemical characteristics of Maccullochella n.sp., eastern freshwater cod water, instream objects, and the immediate sur­ Maccullochella n.sp. and Macquarie perch roundings which influence the water. It is the Macquaria australasica in Appendix lA) were alteration to one or more of these variables that considered to be threatened by overfishing

Bureau of Resource Sciences Proceedings 215 (recreational, commercial and illegal), while the As outlined above, threats to the habitats of red-finned blue-eye (Scaturiginichthys freshwater fishes are many, and threatening vermeilipinnis) was considered to be under threat processes are often interlinked. Although there due to collection. remains a paucity of data on the habitat require­ ments of many fishes and those habitat variables Barriers which prevented the upstream mi­ that are predictive offish community structure, gration of fish and the downstream movements much general knowledge is available (Koehn and dispersal of larvae were considered to seri­ this meeting). Whilst appropriate research is ously affect two species (see Mary River cod essential and must be encouraged, programmes Maccullochella n.sp. and Australian grayling to mitigate degradation of freshwater habitats Prototroctes maraena in Appendix IA), although must be initiated now with the best data pres­ the effects of such barriers may well be under­ ently available. estimated due to the lack of knowledge of the movement requirements of many species. A lack In the case of some of the smaller species of genetic diversity in small populations was also that occur in very fragile and restricted habitats considered to be a threat in itself, and this is likely e.g. the honey blue eye (Pseudomugil mellis) to apply to several other species. that occurs in coastal wallum swamps and the red-finned blue eye (Scaturiginichthys venneilipinnis) that inhabits shallow artesian soaks, total habitat destruction remains a real Conclusion possibility. In these cases the protection of spe­ According to Wager and Jackson (in press) there cific areas by the development of management are about 195 species and subspecies offreshwa­ plans with local landholder cooperation or the ter fish formally described from Australian wa­ creation of conservation reserves or national ters. A further 22 taxa are currently recognised parks is a valid management option. However, but have yet to be formally described. as illustrated by the case of the Lake Eacham rainbowfish (Melanotaenia eachamensis), pro­ Since European settlement, no species are tection within a national park does not necessar­ known to have become extinct although one ily mean protection from introduced or species, the Lake Eacham rainbowfish translocated fishes. (Melanotaenia eachamensis), no longer occurs in the wild. Five per cent of the fauna are now In the case of larger and more widely dis­ classified as endangered (i.e. they are in danger tributed species, e.g. Macquarie perch of extinction in the near future) and 13% are (Macquaria austra/asica) and Australjan gray­ under threat. ling (Prototroctes maraena), a total catchment management approach is required to ensure The major threats t0 freshwater fishes ap­ habitat protection. Cooperation from local com­ pear to be interaction with introduced species munities, particularly private landholders, is and habitat degradation (see also Koehn and essential. Measures to reduce catchment ero­ O'Connor 1990a; Wager and Jackson in press). sion and to protect remnant native riparian veg­ Threats from introduced species range from com­ etation and replanting programmes to enhance it petitive interactions for food and space to direct where necessary, will be of significant benefit to predation. At present, the two species most often a large number of threatened and non-threat­ implicated are brown trout (Salmo trntta) and ened fishes alike. gambusia (Gambusia holbrooki). Whilst total eradication of these species is impractical, local­ Water extraction and impoundments can ised programs to remove these sp�cies in areas have major impacts on threatened fishes. Con­ containing threatened fishes is a valid manage­ sideration must be given to the needs of these ment tool. fishes in the management of water extraction

216 Bureau of Resource Sciences Proceedings and the control of impoundment outflows. Al­ Neosilurus n.sp., Chlamydogobius n.sp. and terations to low-level offtakes, which may change Macquaria australasica. It was noted that the both water temperatures and water quality down­ taxonomy of Maccul!ochella n.spp. (eastern stream, and the inclusions of fishways are re­ freshwater cod and Mary River cod) has been quired to negate these widespread problems. resolved (Rowland in press). Controls over snag removal and other forms of Recommendation. That the Australian So­ instream habitat destruction (e.g. channelisation, ciety for Fish Biology encourages the necessary stream clearing etc.), are also needed. taxonomic work to enable formal descriptions The number of species on the conservation of present! y undescribed taxa to be published as status listing has increased from 59 in 1985 to 72 a matter of urgency. in 1992. More significantly, the numberof threat­ ened fishes (i.e. those in the endangered and Updating of other conservation vulnerable, potentially threatened or indetermi­ status listings nate categories) has risen from 15 to 28. Whilst A number of other conservation status listings this may in part be due to more data now being of fish species exist. Most of these use the ASFB available on some species, it is significant that listing as their basis (e.g. the Australian and no threatened species has been removed from New Zealand Environmental Conservation the list in the seven years since 1985 as a result Council list of Endangered Vertebrate Fauna, of rehabilitation measures. The species recov­ the IUCN Threatened Australian Freshwater ery programs initiated by the Endangered Spe­ Fishes List). However, these listings do not keep cies Unit of the Australian National Parks and pace with the annual changes to the ASFB Wildlife Service may assist in this area (see listing. Wager and Jackson in press). Recommendation. That the Annual ASFB Threatened Fishes List be forwarded to all rel­ evant agencies compiling conservation status Recommendations listings with a view to their listings being up­ dated annually in accordance with the ASFB At its annual meeting at Victor Harbour, South list. Australia, in 1992, the Threatened Fishes Com­ mittee of ASFB outlined a number of areas of concernin relation to the conservation of fishes. Attention to fish species in Indeterminate These concerns are recorded here in the form of and Uncertain Status categories Recommendations. Those taxa that fall into Indeterminate or Uncer­ tain Status categories are placed there because there are insufficient data to list them in other Taxonomy categories. There is a danger that they will The Threatened Fishes Committee is concerned remain there if the necessary data collection is about the number of undescribed taxa that ap­ not encouraged. For example, the blind cave eel pear on the list (e.g. Chlamydogobius sp., (Ophisternon candidum)has been in the Inde­ Glossogobius sp., Mogurndasp. etc) and other terminate category since 1985. groups which have been identified as requiring taxonomic work (e.g. Macquaria australasica). Recommendation. That the Australian So­ Some taxa have remained undescribed since the ciety for Fish Biology encourages the necessary list was formulated in 1985. Taxa which are of research work to be undertaken to collect the particular concern and which should be given required data on taxa in the Indeterminate and priority are: Galaxiasfuscus, Mogurndan.sp., Uncertain Status categories.

Bureau of Resource Sciences Proceedings 217 Need to address threats to fishes References o There is a requirement f r the Society to be Cadwallader, P.L. (1978). Some causes of the decline in proactive in addressing threats to fishes. There range and abundance of native fish in the Murray­ is a danger that no action will be taken until a Darling River system. Proceedings of the Royal Soci­ species becomes listed, whereas threatening ety of Victoria 90, 211-224. processes could be addressed before this happens. Fletcher, A.R. (1979). Effects of Sa/1110 trulla on Galaxias For example, the Threatened Fishes Committee o/idus and macroinvertebrates in stream communities. received a nomination in 1992 to list silver MSc thesis, Monash University, Clayton, Victoria. perch (Bidyanus bidyanus) as 'Restricted' due Harris,J.H. (Ed.)(1987). Proceedings of the Conference 011 to evidence of decline in populations in New Australian Threatened Fishes. Australian Society for South Wales. The Committee did not accept the Fish Biology and Department of Agriculture NSW, nomination because silver perch are still Sydney, 70pp. comparatively abundant in relation to other Ingram, B.A., C.G. Barlow, J.J. Burchmore, G.J. Gooley, species currently listed as restricted. However, S.J. Roland and A.C. Sanger (1990). Threatened there is a need to address the processes native freshwater fishes in Australia - some case threatening silver perch now or inevitably it will histories.Journalof Fish Biology 37(Supplement A), 175-182. be listed in the future. Jackson, P.D. ( 1981 ). Trout introduced into south-eastern Recommendation. That the Australian Australia: their interaction with native fishes. Victo­ Society for Fish Biology becomes proactive in rian Naturalist 98, 18-24. addressing threatening processes. The Society's Jackson, P.D. and W.D. Williams (1980). Effects of brown proposed Habitat Committee may be an avenue trout, Sa/1110 tru//a L. on the distribution of some for this. There should be close liaison between native fishes in three areas of southern Victoria. this Committee and the Threatened Fishes Australian Journal of Marine and Freshwater Re­ Committee. search 31, 61-67. Koehn, J.D. and W.G. O'Connor (1990a). Threats to Vic­ torian native freshwater fish. Victorian Naturalist 107, 5-12, Acknowledgements Koehn,J.D. and W.G. O'Connor (l990b). Biological !1?for- The authors wish to thank J. Harris for his 111atio11 for Management ofNative Freshwater Fish in foresight in convening the initial conferencein Victoria. Government Printer, Melbourne. 165pp. 1985 and establishing the Threatened Fishes Koehn, J.D. (this meeting). Freshwater fish habitats: Key Committee. The following people attended the factors and methods to determine them. 1992 Committee meeting and contributed to a Lloyd, L. ( 1989). Ecological interaction of Gambusia lively debate; W. Fulton, D. Pollard, P. Unmack, holbrooki with Australian native fishes. In: Pollard, J. Anderson, K. Kukolic, S. Saddlier, M. Mallen­ D.A. (ed). Introduced and translocation fishes and Cooper, B. Pierce andP. Cadwallader. In addition their ecological effects. ASFB Workshop Proceed­ ings No.8, 94--97. nominations were provided by T. Raadik, H. Larson, K. Bishop, G. Gooley and J. Douglas. McKay, R.J. (1989). Exotic and translocated freshwater Much of the data presented in Appendix 1 A was fishes in Australia. In: De Silva, S.S. (ed.) Exotic aquatic organisms in Asia. Proceedings of the Work­ collected while two of the authors were preparing shop 011 Introduction of Exotic Aquatic Organisms in the Action Plan forAustralian Freshwater Fishes Asia. Asian Fisheries Society Special Publications 3, for the Australian National Parks and Wildlife 21-34. Service. The Service's financial support and Pollard, D.A., B.A. Ingram, J.H. Harris and L.F. Reynolds. foresight in commissioning this project is Threatened fishes in Australia-an overview. Jour­ gratefully acknowledged. nal of Fish Biology 37 (Supplement A), 67-78.

218 Bureau of Resource Sciences Proceedings Rowland, S.J. (in press). Maccullochella ikei, an Endan­ gered species of Freshwater Cod (Pisces: Percichthyidae) fromthe Clarence River System, New South Wales and M. pee/ii mariensis a New South Wales subspecies from the Mary River System, Queensland. Records of the Australian Museum. Tilzey, R.D.J. (1976). Observations on interactions be­ tween indigenous Galaxidae and introduced Salmonidae in the Lake Eacumbeme catchment, New South Wales.Australian Journal of Marine and Fresh­ water Research 27, 551-564.

Wager, R. and P.D. Jackson (in press). The Action Plan for Australian Freshwater Fishes. Australian National Parks and Wildlife Service, Canberra.

Bureau of Resource Sciences Proceedings 219 Table 1. The 1992 Conservation status listing of Australian fish species

Category Scientifc name Common name

Extinct No species Endangered *Chlamydogobius n.sp. Elizabeth Springs goby Galaxias fontanus Swan galaxias Galaxias ji1scus barred galaxias Galaxias johnstoni Clarence galaxias Galaxias pedderensis Pedder galaxias Maccullochella macquariensis trout cod * Maccullochella n.sp. eastern freshwatercod * Maccullochella n.sp. Mary River cod Melanotaenia eachamensis Lake Eacham rainbowfish Nannoperca oxleyana Oxleyan pigmy perch Scaturiginichthys vermeilipinnis red-finned blue-eye Vulnerable Carcharias taurus grey nurse shark Galaxias tanycephalus saddled galaxias * Mogurndan.sp. Flinders Ranges gudgeon Nannoperca variegata variegated pigmy perch Pseudomugil mellis honey blue-eye Potentially Threatened Craterocephalus dalhousiensis Dalhousie hardyhead Craterocephalusj7uviatilis Murray hardyhead Craterocephalus gloveri Glover's hardyhead Epinephelus daemelii black cod Galaxias parvus swamp galaxias Galaxiella pusilla dwaif galaxias Mordacia praecox non-parasitic lamprey * Neosilurus n.sp. Dalhousie catfish Edelia obscura Yarra pigmy perch Prototroctes maraena Australian grayling Indeterminate Macquaria australasica Macquarie perch Ophisternoncandidum blind cave eel Restricted Cairnsichthysrhombosomoides Cairns rainbowfish * Chlamydogobius n.sp. Dalhousie goby Craterocephalus amniculus Darling River hardyhead Craterocephalus centralis Finke River hardyhead Craterocephalus helenae Drysdale hardyhead Craterocepha!us lentiginosus Prince Regent hardyhead Craterocephalus marianae Magela hardyhead Galaxias rostratus flat-headedgalaxias Galaxiella munda westernmud minnow

220 Bureau of Resource Sciences Proceedings Table 1. The 1992 Conservation status listing of Australian fish species (continued)

Category Scientifc name Common name

Galaxiella nigrostriata black-striped minnow * Glossogobius n.sp. Mulgrave goby Hannia greenwayi Greenway's grunter Hephaestus epirrhinos long-nose sooty grunter Hypseleotris aurea golden gudgeon Kimberleyeleotris hutchinsi Mitchell gudgeon Kimberleyeleotris notata Drysdale gudgeon Leiopotherapon aheneus Fortesque grunter Leiopotherapon macrolepis large-scale grunter Lepidogalaxias salamandroides salamanderfish Melanotaenia exquisita exquisite rainbowfish Melanotaenia gracilis slender rainbowfish Melanotaenia pygmaea pygmy rainbowfish Milyeringa veritas blind gudgeon Mogurndaadspersa southernpurple-spotted gudgeon * Mogurndan.sp. false-spotted gudgeon Paragalaxias mesotes Arthur's paragalaxias Pingalla midgleyi Midgley's grunter Scleropages leichardti Saratoga Scortum parviceps small-headed grunter Syncomistes rastellus Drysdale grunter Uncertain Status Ambassis elongatus yellowfin perchlet Carcharodon carcharias great white shark Cinedotusfroggatti Froggatt's catfish Hypseleotris ejuncida slender gudgeon Hypseleotris kimberleyensis BarnettRiver gudgeon Hypseleotris regalis Prince Regent gudgeon * Neosilurus n.spp. undescribed tandans Pingalla gilberti Gilbert's grunter Scortum hillii leathery grunter * Scortum n.sp. Angalarri grunter Syncomistes kimberleyensis Kimberley grunter * Tandanus n.sp. Bellinger River tandan Thryssa scratchleyi freshwateranchovy Toxotes oligolepis big-scale archerfish

Species identified by the Committee at its 1990 meeting as requiring investigations of their status were: Thunnus maccoyii southern bluefin tuna

* Denotes taxa where formal taxonomic description has not been published but where listing is essential because of concern over their conservation status. Early formalpublication will be encouraged to resolve their taxonomic status.

Bureau of Resource Sciences Proceedings 221 Table 2. Numbers of fishin each category of Australian threatened fishspecies

Classification 1992 1991 1990 1989 1988 1985 Extinct 0 0 0 0 0 0 Endangered 11 9 8 6 5 4 Vulnerable 5 6 6 5 5 4 Potentially Threatened 10 7 5 4 3 5 Indeterminate 2 2 2 2 2 2 Restricted 30 32 30 31 33 29 Uncertain Status 14 13 13 16 16 15 Total 72 69 64 64 64 59

Table 3. The number of Australian threatened freshwater fishspecies affectedby each threatening process. A category may be the result of more than one process (Appendix IA)

Threatening processes Threatened species category Endangered Vulnerable Pot. Threat. lndetermin. Totals

Interactions with 10 3 6 20 introduced species Instream habitat 8 2 6 16 removal/destruction Riparian veg. removal 8 2 3 13 Sedimentation 5 2 9 Water extraction 3 4 8 flow regulation Reduced water quality 2 3 7 Overfishing/collection 4 1 6 Barriers 2 3 Loss of genetic diversity 2 2 Unknown 3 3

222 Bureau of Resource Sciences Proceedings Appendix 1 A. Summary information Threatening processes: Predation by rainbow for each threatened fish (i.e. trout (Oncorhynchus mykiss) and brown trout Endangered, Vulnerable, Potentially (Salmo trutta). Habitat degradation and sedi­ Threatened and Indeterminate mentation fromforestry and mining operations categories) and road construction. At least one spill of cyanide frommining operations has occurred. Endangered Clarence galaxias, Galaxias johnstoni Elizabeth Springs goby, Chlamydogobius Scott (1936) n.sp. Current distribution: Restricted to the head­ Current distribution: Only in Elizabeth waters of the Clarence River, headwaters of Springs complex, central Queensland. Dyes Rivulet and Dyes Marsh and a lagoon in the Wentworth Hills, south easternTasmania. Habitat: Shallow waters of artesian springs. Habitat: Rocky margins of streams and Threatening processes: Reduction in water lagoons. level due to lowering of water table by water extraction through artificial bores; habitat de­ Threatening processes: Interactions with brown struction due to trampling by domestic stock. trout (Salmo trutta).

Swan galaxias, Galaxias fontanus Pedder galaxias, Galaxias pedderensis Fulton (1978) Frankenberg (1968) Current distribution: Restricted to five small Current distribution: Reported fromtwo small streams in the Macquarie and Swan River drain­ streams draining into Lake Pedder, Tasmania; age in eastern Tasmania. may still occur in three other small streams in the area, but not recently captured. Habitat: Slow to moderately fast flowing streams, around woody debris, rocky pools or Habitat: Slow flowing streams with sandy stream margins. substrate and abundant cover. Threatening processes: Interaction with brown Threatening processes: Interactions with trout (Salmo trutta), cannot co-exist with this climbing galaxias (Galaxias brevipinnis) and/ species, probably due to predation. Habitat al­ or brown trout (Salmo trutta). teration due to forestry operations. Trout cod, Maccullochellamacquariensis Barred galaxias, Galaxias fuscus Cuvier and Valenciennes (1829) Mack (1936) Current distribution: Restricted to a few iso­ McDowall and Frankenberg ( 1981) consider it lated populations in Victoria, New South Wales a junior synonym of G. olidus. Taxonomic and Australian Capital Territory. status needs to be confirmed. Habitat: Inhabits both fast flowing and still Current distribution: Restricted to six small waters; within streams, occurs in fastflowing streams in the upper reaches of the Goulbum water over bedrock, boulder and gravel River between Marysville and Mount Howitt. substrates. Larger individuals inhabit deep holes. Habitat: Upper reaches of small, clear flowing Threatening processes: Interactions with streams in mountainous country with gravel or introduced species: brown trout (Salmo trutta) boulder substrates. Preference for pools. carp ( Cyprinus carpio), redfin (Percafluviatilis)

Bureau of Resource Sciences Proceedings 223 and possibly goldfish (Carassius auratus). Habitat: Formerly found in clear, shallow wa­ Habitat degradation caused by desnagging, ters at margins of Lake Eacham, often amongst removal ofriparian vegetation, flowregulation aquatic vegetation, fallen logs or branches. How­ in diminishing populations, barriers caused by ever individuals could be found throughout sur­ dam and weir constrnction,and overfishing. face waters of the Lake. Threatening processes: Probably interactions Eastern freshwater cod, Maccullochella with translocated species, particularly the mouth n.sp. almighty (Glossamia aprion) but also banded Current distribution: Restricted to Nymboida grunter (Amniataba precoides), archerfish and Mann Rivers in the Clarence River (Toxotes chatareus) and bony bream Drainage, New South Wales. Fingerlings have (Nematolosa erebi). been stocked in the Richmond River Drainage. Oxleyan pigmy perch, Nannoperca oxleyana Whitley (1940) Habitat: Clear, rocky streams. Current distribution: Coastal wallum swamps Threatening process: Overfishing, habitat and streams from the Richmond River area of degradation through accelerated catchment n011hern New South Wales and in Queensland erosion, strea.m siltation and loss of riparian north of Brisbane from the Caboolture Shire to vegetation. Loss of genetic diversity in Tin Can Bay including Moreton and Fraser diminishing populations. Islands. Mary River cod, Maccul/ochellan.sp. Habitat: Usually among emergent vegetation or near vertical or undercut banks among fine Current distribution: Restricted to a few of rootlets of riparian vegetation. the larger tributaries of the Mary River, south eastern Queensland. Threatening processes: Loss of habitat from residential housing development, exotic pine Habitat: Found in deeper pools of relatively plantations, mining and agriculture. May be undisturbed tributaries where fallen timber, affectedby the introduced gambusia ( Gamhusia branches and boulders provide cover. holbrooki), especially in the Noosa River. Threatening processes: Flow regulation and physical barriers caused by construction of Red finned blue-eye, Scaturiginichthys dams and weirs. Loss of native riparian vermeilipinnis lvantsoff et al. (1991) vegetation and siltation from accelerated Current distribution: Only known fromfour catchment erosion due to agriculture and forestry artesian springs in the Edgebaston Spring practices. Stream channel drainage from sand Complex near Aramac, central Queensland. and gravel extraction and possible interactions with translocated species, golden perch Habitat: Shallow springs in Mitchell grass (Macquaria ambigua) and silver perch country. (Bidyanus bidyanus). Overfishing. Threatening processes: Interaction with introduced gambusia (Gambusia holbrooki). Lake Eacham rainbowfish, Me/anotaenia Habitat destruction due to trampling by both eachamensis Allen and Cross (1982) domestic and feral stock. Habitat destruction Current distribution: No longer found inwild due to excavation of springs for stock watering but several captive populations exist. and possible overcollection for aquarium trade.

224 Bureau of Resource Sciences Proceedings Vulnerable Habitat: Among or near emergent aquatic veg­ etation in streams and lakes usually associated Saddled galaxias, Galaxias tanycephalus with wallum swamps. Fulton (1978) Threatening processes: Habitat destruction by Current distribution: Arthur's Lake and residential development, forestry operations, Woods Lake, central plateau, Tasmania. agriculture and mining. Interactions with intro­ Habitat: Among rocks at margins of lakes. duced gambusia (Gambusia holbrooki) also a Larval stages pelagic. threat together with collection for aquarium trade. Threatening processes: Predation by brown trout (Salmo trutta). Possibly nutrient enrich­ ment of Woods Lake. Potentially Threatened Dalhousie hardyhead, Craterocephalus Flinders Ranges gudgeon, Mogurndasp. dalhousiensis Glover (1989) Current distribution: Waterways of Gammons Current distribution: Known from7 springs Ranges National Park in North Flinders Ranges, within the Dalhousie Springs Complex, South South Australia. Australia. Habitat: Small isolated waterholes. Habitat: Medium to large springs with warm, Threatening processes: Feral goat populations flowing water. may have caused eutrophication of pools. Goats Threatening processes: Potential reduction in have been removed. artesian flows, pollution of surface waters, es­ tablishment of exotic fish and uncontrolled ef­ Variegated pigmy perch, Nannoperca fects of tourists. variegata Kuiter and Allen (1986) Current distribution: Only found in Ewens Murray hardyhead, Craterocephalus Ponds near Mt Gambier, South Australia and f/uviatilislvantsoff et al. (1987) Glenelg River near Winnap, WesternAustralia. Current distribution: Restricted to Kerang Habitat: Clear flowing streams or ponds with Lakes area, Victoria, and possibly the nearby abundant aquatic vegetation. MmTay River. Threatening processes: Destruction of habitat Habitat: Margins of slow, lowland rivers and in including removal of aquatic and riparian veg­ lakes, billabongs and backwaters among aquatic etation and drainage of swamps. Interactions plants and over gravel beds. with introduced species including gambusia Threatening processes: Not known but gen­ (Gambusia holbrooki), redfin (Percafluviati !is), eral comments on threats outlined in this paper brown trout (Salmo trutta), rainbow trout probably apply. (Oncorhynchus mykiss) and carp (Cyprinus carpio). Glovers Hardyhead, Craterocephalus g/overi Crowley and lvantsoff (1990) Honey blue-eye, Pseudomugil met/is Allen and lvantsoff(1982) Current distribution: Known from 4 springs within Dalhousie Springs Complex, South Current distribution: Lakes and creeks on Australia. Fraser Island and on mainland between Caboolture and Tin Can Bay, south eastern Habitat: Medium to large springs with warm Queensland. flowing water.

Bureau of Resource Sciences Proceedings 225 Threatening processes: Potential reduction in Dalhousie catfish, Neosifurus n.sp. artesian flows, pollution of surface waters, es­ Current distribution: Known from 5 springs tablishment of exotic fishand uncontrolled ef­ within the Dalhousie Springs Complex, South fectsof tourists. Australia. Swamp galaxias, Galaxias parvus Habitat: Medium to large springs with warm, Frankenberg (1968) flowing water. Current distribution: Restricted to the head­ Threatening processes: Potential reduction in waters of the Gordon and Huon Rivers in south artesian flows, pollution of surface waters, es­ westernTasmania. tablishment of exotic fish and uncontrolled effectsof tourists. Habitat: Open shallow stretches of rivers or vegetation margins of swamps, quiet pools and Yarra pigmy perch, Ede/ia obscura backwaters. Klunzinger (1872) Threatening processes: Not known at this stage. Current distribution: A fewlocations in south west Victoria and south west of South Aus­ Dwarf galaxias, Galaxiellapusilla tralia. Mack (1936) Habitat: Slow flowing stream or still water Current distribution: Limited to north eastern among aquatic vegetation. Tasmania, Flinders Island, Victoria and South Australia. In Victoria, main populations are in Threatening processes: General destruction the Grampians and foursites around Melbourne. of habitat including removal of aquatic and In South Australia found in swamps and drains riparian vegetation, and drainage of swamps. in the south east of the State. Interactions with introduced species including gambusia ( Gambusia holbrooki), redfin (Perea Habitat: Slow flowing waters of swamps and fluviatilis), brown trout (Sa Imo trutta) and carp drains or backwaters of creeks, often among (Cyprinus carpio). aquatic vegetation in shallow waters. Threatening processes: Habitat destruction Australian grayling, Prototroctes maraena from draining of swamps, channelisation and Gunther (1864) removal of aquatic and riparian vegetation, and Current distribution: Patchy distribution in interactions with introduced species, particu­ coastal rivers from the Grose River, west of larly gambusia (Gambusia holbrooki). Sydney, through New South Wales, Victoria and eastern South Australia. Also occurs in Non-parasitic lamprey, Mordacia praecox Tasmania and on King Island in Bass Strait. Potter (1968) Often foundin small numbers only. Current distribution: Known only from the Habitat: A diadromous species with larvae Moruya and Tuross Rivers in south eastern New apparently being swept to estuaries and return­ South Wales and possibly from the La Trobe ing to freshwaterafter 4-6 months. Freshwater River in Victoria although this has not been habitats include large and small coastal rivers. confirmed. It is a midwater species. Habitat: Not known. Threatening processes: Barriers to movement Threatening processes: Details not known, caused by dams. River regulation. Habitat deg­ general habitat degradation. radation caused by siltation from catchment

226 Bureau of Resource Sciences Proceedings erosion, and stream channel damage caused by Habitat: Subterranean cavernsand fissures. sand and gravel extraction. Possible predation Threatening processes: Little known but po­ by brown trout (Salmo trutta) on juveniles. tential to degrade water quality of subterranean waters has already been demonstrated by Indeterminate Mowbowra Well being filled with rubbish, and siltation of Dozer Cave (connected to Gnamma Macquarie perch, Macquaria australasica Hole) due to runoff fromold mining operations. Cuvier and Valenciennes (1830) Both these sites have been rehabilitated. Current distribution: Three genetic stocks are presently recognised: • Shoalhaven stock, east of the Great Divid­ Reference ing Range in New South Wales. Possibly McDowall, R.M. andR.S. Frankenberg ( 1981). TheGalaxiid limited to lower reaches of Shoalhaven fishes of Australia. Records of the Australian Museum River system. 33(10), 443-605. • Hawkesbury stock, widespread in Hawkesbury River in New South Wales. • Murray-Darling stock, known from the Murrumbidgee and Lachlan Rivers in New South Wales and from the Loddon, Goulbum, Ovens and Mitta Mitta Rivers in Victoria. May have been stocked in im­ poundments in Shoalhaven and Hawkesbury River. Also stocked in Wannon, Barwon and Yarra Rivers. Habitat: A riverine, schooling species, prefers deep rocky holes with considerable cover. Threatening processes: Destruction of habitat by siltation of spawning sites, blanketing of riffle areas (invertebrate food source) and infilling of deep holes. Interaction with intro­ duced species including brown trout (Salmo trutta) and redfin (Percafluviatilis). Increased nutrient loads associated with urban develop­ ment, river regulation and overfishing.

Blind cave eel, Ophisternon candidum Mees (1962). Current distribution: Not well known. In the last 15 years has only been observed in two locations, Gnamma Hole and Mowbowra Well in Western Australia. Probably distributed throughout the subterranean system fromjust south of Exmouth, north to North West Cape and south to Yardie Creek.

Bureau of Resource Sciences Proceedings 227 APPENDIX 2: WORKSHOP PROGRAM

SUSTAINABLE FISHERIES THROUGH SUSTAINING FISH HABITAT (Convenor: Barry Bruce South Australian Department of Fisheries)

Day 1 (Wednesday, 12 August 1992) 0900-0915 SESSION 1-INTRODUCTION-Dr Julian Pepperell, President, ASFB 0915 -1000 Keynote Address-Dr Stanley Moberly, Northwest Marine Technology, Seattle "Fish Habitat is Where It's At: It is more fun to fight over more fish than less fish." 1000 -1030 Morning Tea 1030-1230 SESSION 2-A MANAGER'S VIEW OF FISH HABITAT Chailperson: Rob Lewis, Department of Fisheries, SA Rapporteur: Gina Newton, Bureau of Rural Resources, ACT Panel Speakers: Karen Edyvane, Department of Fisheries, SA "An ecosystem approach to marine fisheries management" Ross Winstanley, Marine Science Laboratories, VIC "Estuarine issues fromthe manager's viewpoint" Peter Jackson, QDPI Fisheries, QLD "Freshwater protection-a manager's perspective" 1230 1330 Lunch 1330 1500 SESSION 3-ORGANISMS AND ENVIRONMENT AL RELATIONSHIPS I-Case Studies Chailperson: Peter Gehrke, Inland Fisheries Research Station, NSW Rapporteur: Gary Thorncraft,Fisheries Research Institute, NSW Panel Speakers: Ian Poiner, CSIRO Fisheries QLD "Maintain or modify alternative views of managing critical fisheries habitat" Stephen Swales, Fisheries Research Institute, NSW "Rehabilitation, mitigation and restoration of fishhabitat in regulated rivers" Mick Bales, Department of Water Resources, NSW "A habitat fit for fish-an aim of biomanipulation"

228 Bureau of Resource Sciences Proceedings Rick Morton, WBM Oceanics, QLD "Enhancement of estuarine habitats in association with development" 1500- 1530 AfternoonTea 1530- 1700 SESSION 4-ORGANISMS AND ENVIRONMENTAL RELATIONSHIPS II-Key Variables and Broad Based Issues Chairperson: Bryan Pierce, Department of Fisheries, SA Rapporteur: Mervi Kangas, Department of Fisheries, SA Panel Speakers: Peter Young, CSIRO Fisheries, T AS "Defining key factors relating marine fishes and their habitats" Neil Loneragan, CSIRO Fisheries, QLD "Defining key factors relating fish populations in estuaries and their habitat" John Koehn, Arthur Rylah Institute, VIC "Freshwater fishhabitats : key factors and methods to determine them" 1700- 1730 Discussion of Day 1 Rapporteur: David Smith, Marine Science Laboratories, VIC

Day 2 (Thursday 13 August 1992) 0900 - 1030 SESSION 5-IMPACT OF HUMAN ACTIVITIES ON HABITAT AND FISHERIES Chairperson.· Murray McDonald, Marine Science Laboratories, VIC Rapporteur: Patrick Coutin, Marine Science Laboratories, VIC Panel Speakers: Robert Campbell, CSIRO Fisheries, TAS "Effects of trawling on the marine community on the North West Shelf of Australia and implications for sustainable fisheries management" Greg Jenkins, Victorian Institute of Marine Science, VIC "Ecological basis for parallel declines in seagrass habitat and catches of commercial fish in Western Port Bay, Victoria" Martin Mallen-Cooper, Fisheries Research Institute, NSW "Habitat changes and declines of freshwaterfish in Australia : what is the evidence and do we need more?" 1030- 1100 MorningTea

Bureau of Resource Sciences Proceedings 229 1100 - 1230 SESSION 6-ALTERNATIVE USES (economic, social and political)-KEY VALUES Chabperson: Russell Reichelt, Bureau of Rural Resources, ACT Rapporteur: John Robertson, GBRMPA, QLD Panel Speakers: David Pollard, Fisheries Research Institute, NSW "Maximising the potential for both sustainable fisheries and alternativeuses of fish habitat through marine harvest refugia" Andrew Staniford, Department of Mines and Energy, SA "Alternativeuses of aquatic habitats : an economic viewpoint" 1230- 1330 Lunch 1330- 1530 SESSION 7-MANAGEMENT (amelioration, enhancement, conservation) Chailperson: Barbara Richardson, NSW Fisheries, NSW Rapporteur: David Pollard, Fisheries Research Institute, NSW Panel Speakers: Bob O'Boyle, Bedford Institute of Oceanography, CANADA "The management of the marine habitat" Jenny Burchmore, NSW Fisheries, NSW "Management of the estuarine habitat" Wayne Fulton, Inland Fisheries Commission, TAS "Managing freshwaterfish habitat" 1530- 1600 AfternoonTea 1600 - 1700 GENERAL DISCUSSION Chailperson: Peter Young, CSIRO Fisheries, TAS Rapporteur: Peter Last, CSIRO Fisheries, TAS Panel Speakers: Rob Lewis, Department of Fisheries, SA Peter Gehrke, Inland Fisheries Research Station, NSW Bryan Pierce, Department of Fisheries, SA Murray MacDonald, Marine Science Laboratories, VIC Russell Reichelt, Bureau of Rural Resources, ACT Barbara Richardson, NSW Fisheries, NSW 1700 - 1730 SUMMING UP Dr Stanley Moberly (Keynote Speaker)

230 Bureau of Resource Sciences Proceedings APPENDIX 3: LIST OF PARTICIPANTS

ALLEN KR 20/8 Waratah Street CADWALLADER P L Dept. ofConservation & CRONULLA NSW 2230 Environment Private Bag 20 ANDERSONJR Univ. ofNew England-Nthn ALEXANDRA VIC 3714 Rivers Campus PO Box 157 CAMERON DS Sthn .Fisheries Centre Q.D.P.I. LISMORE NSW 2480 P.O. Box 76 DECEPTION BAY QLD 4508 BAKER DL Sth. Aust. Res. & Dev. Inst.- Fisheries CAMPBELL RA CSIRO Division of Fisheries GPO Box 1625 GPO Box 1538 ADELAIDE SA 5001 HOBART TAS 7001 BAKERJL Sth. Aust. Res. & Dev. Inst.- CLAGUE CI 67 Old Smithfield Rd Fisheries Freshwater GPO Box 1625 CAIRNS QLD 4870 ADELAIDE SA 5001 CROSS H NSW Dept. Water Resources BALES MT Dept. Water Resources P.O. Box 370 10 Valentine Ave PARRAMATTA NSW 2124 PARRAMATTA NSW 2150 CONNOLLY R Dept. ofZoology, Univ. of BAULCH G Dept. Primary Industry & Fisheries Adelaide P.O. Box 990 GPO Box 598 DARWIN NT 0801 ADELAIDE SA 5001 BENSON C G Dept. Applied Sciences, Univ. COUTIN PC Marine Sciences Laboratories Tasmania P.O. Box 114, P.O. Box 1214 QUEENSCLIFF VIC 3225 LAUNCESTON TAS 7250 DAVIES CR School ofBiol. Sci.,Ja mes Cook BERTONI M Bureau of Resource Sciences Univ. P.O. Box Ell, Queen Victoria Tee, Post Office CANBERRA ACT 2600 TOWNSVILLE QLD 4811 BIRD FL Dept. ofZoology., Univ. of DIPLOCK J NSW Fisheries Melbourne P.O. Box 4805 PARKVILLE VIC 3052 ST. LEONARDS NSW 2065 BRIDGE N School of Biol. Sciences, DIXON P Centre for Marine Sciences Flinders Univ. Univ. ofNSW P.O. Box 1 Sturt Rd, KENSINGTON NSW 2034 BEDFORD PARK SA 5042 EDYVANE K Sth. Aust. Res. & Dev. Inst.- BROWN LP Marine Sciences Laboratories Fisheries P.O. Box 114, GPO Box 1625 QUEENSCLIFF VIC 3225 ADELAIDE SA 5001 BRUCE B D Sth. Aust. Res. & Dev. Inst.- EVANS K Sth. Aust. Res. & Dev. Inst.- Fisheries Fisheries GPO Box 1625 GPO Box 1625 ADELAIDE SA 5001 ADELAIDE SA 5001 BURCHMOREJ NSW Fisheries FRUSHER S D Div. of Sea Fisheries, D.P.1.F. & E. P.O. Box 4805 P.O. Box 192B ST. LEONARDS NSW 2065 HOBART TAS 7001

Bureau of Resource Sciences Proceedings 231 FULTON W Inland Fisheries Commission JONES K Sth. Aust. Res. & Dev. Inst.- 127 Davey St Fisheries HOBART T AS 7000 GPO Box 1625 ADELAIDE SA 5001 GEHRKE PC NSW Fisheries P.O. Box 182 JORDAN AR Dept. of Primary Industries & NARRANDERA NSW 2700 Fisheries Crayfish Point GLAISTERJ P Sthn Fisheries Centre Q.D.P.I. TAROONA TAS 7053 P.O. Box 76 DECEPTION BAY QLD 4508 KAILOLA P J Bureau of Resource Sciences P.O. Box Ell, Queen Victoria Tee, GOMON MF Museum of Victoria CANBERRA ACT 2600 285 Russell St MELBOURNE VIC 3000 KANGAS MI Sth. Aust. Res. & Dev. Inst.- Fisheries HALL N G Bernard Bowen Fisheries Research GPO Box 1625 Institute ADELAIDE SA 5001 P.O. Box 20 NORTH BEACH WA 6020 KENYON RA CSIRO Division of Fisheries HANCOCK DA 29 Woodlands Way P.O. Box 120 CLEVELAND QLD 4163 QUINDALUP WA 6281

HAYWOOD M CSIRO Division of Fisheries KINLOCH MA Sth. Aust. Res. & Dev. Inst.- P.O. Box 120 Fisheries CLEVELAND QLD 4163 GPO Box 1625 ADELAIDE SA 5001 HOBDAY D Marine Sciences Laboratories P.O. Box 114, KOEHNJD Arthur Rylah Institute QUEENSCLIFF VIC 3225 123 Brown St. HEIDELBERG VIC 3084 HOUGHTON BR 6 Femley Ave McLEOD VIC 3085 KUITER R 110 Kananook Ave SEAFORD VIC 3198 HUGHES D School of Biol. Sciences, Macquarie Univ. KUKOLIC K Dept. of Environment, Land & NORTH RYDE NSW 2109 Planning P.O. Box 1065 JACKSON B Sth. Aust. Res. & Dev. Inst.- TUGGERANONG ACT 2901 Fisheries GPO Box 1625 LAST P R CSIRO Division of Fisheries ADELAIDE SA 5001 GPO Box 1538 HOBART TAS 7001 JACKSON G Sth. Aust. Res. & Dev. Inst.- Fisheries LAURENSON F A Fisheries Research Institute GPO Box 1625 P.O. Box 21 ADELAIDE SA 5001 CRONULLA NSW 2230

JACKSON PD Sthn Fisheries Centre Q.D.P.I. LEADBITTER D Ocean Watch P.O. Box 76 P.O. Box 247 DECEPTION BAY QLD 4508 PYRMONT NSW 2009

JENKINS GP P.O. Box 138 LENANTON R C J Bernard Bowen Fisheries Research QUEENSCLIFF VIC 3225 Institute P.O. Box 20 JOLL C P Australian Fisheries Management NORTH BEACH WA 6020 Authority P.O. Box 7051 LEWIS RJ R.M.B. 5462 CANBERRA CENTRE ACT 2610 SHEPPARTON VIC 3631

232 Bureau of Resource Sciences Proceedings LEWIS RK Sth. Aust. Res. & Dev. Inst.- NEIRA F J School of Biol. & Env. Sciences Fisheries Murdoch Univ. GPO Box 1625 MURDOCH WA 6150 ADELAIDE SA 5001 NEWTON GM Bureau of Resource Sciences LIGHT B R P.O. Box 244 P.O. Box ElI, Queen Victoria Tee, ROSANNA VIC 3084 CANBERRA ACT 2600 LONERAGAN N CSIRO Division ofFisheries NOWARA G Australian Maritime College P.O. Box 120 P.O. Box 986 CLEVELAND QLD 4163 LAUNCESTON TAS 7250 LOWRY MB School of Biol. Sciences, Univ. O'BOYLE RN Dept. ofFisheries & Oceans ofNSW P.O. Box 550 P.O. Box I HALIFAX NOVA SCOTIA KENSINGTON NSW 2034 CANADA 831 257 LUSCOMBEM 11 Folkstone Rd O'CONNORJP Arthur Rylah Institute BRIGHTON SA 5048 123 Brown St. HEIDELBERG VIC 3084 MACDONALD CM Marine Sciences Laboratories P.O. Box 114, O'CONNOR WG Arthur Rylah Institute QUEENSCLIFF VIC 3225 123 Brown St. HEIDELBERG VIC 3084 MALLEN-COOPERM Fisheries Research Institute P.O. Box 21 O'KANECJ Fisheries Research Institute CRONULLA NSW 2230 P.O. Box 21 CRONULLA NSW 2230 MATERIA CJ Museum ofVictoria 285 Russell St OKS EM Dept. of Environment & Planning MELBOURNE VIC 3000 GPO Box 667 ADELAIDE SA 5001 MESSNER K P.O. Box 405 CEDUNA SA 5690 OLSEN AM II Orchard Grove, NEWTON SA 5074 MISKIEWICZ A G NSW Water Board - Env. Projects Unit O'MAHONY DJ Arthur Rylah Institute P.O. Box 453 123 Brown St. SYDNEY SOUTH NSW 2000 HEIDELBERG VIC 3084 MOBERLY S J Northwest Marine Technology PARAS G Dept. of WildlifeReserves Inc., La Trobe University P.O. Box 99488 BUNDOORA VIC 3083 SEATILE WA 98199-0488 PEPPERELL J G Pepperell Research Pty. Ltd. USA P.O. Box 818 MORRISON AK Marine Sciences Laboratories CARINGBAH NSW 2229 P.O. Box 114, PIERCE BE Sth. Aust. Res. & Dev. Inst.- QUEENSCLIFF VIC 3225 Fisheries MORTON RM WBM Oceanics Australia Pty. GPO Box 1625 Ltd. ADELAIDE SA 5001 P.O. Box 203 PITCHER CR CSIRO Division ofFisheries SPRING HILL QLD 4004 P.O. Box 120 CLEVELAND QLD 4163 MURRAY AJ Dept. of Conservation & Environment POINER IR CSIRO Division ofFisheries P.O. Box 260 P.O. Box 120 ORBOST VIC 3225 CLEVELAND QLD 4163 MUSAJ Centre forMarine Sciences POLLARD DA Fisheries Research Institute Univ. ofNSW P.O. Box I P.O. Box 21 KENSINGTON NSW 2034 CRONULLA NSW 2230

Bureau of Resource Sciences Proceedings 233 POOLE R Museum of Victoria STEWART B D Zoology Dept 528 Swanston St. University of Melbourne MELBOURNE VIC 3000 PARKVILLE VIC 3052

PRINCEJ D P.O. Box 209 STOBUTSKI IC 24 Wilmett St LEEDERVILLE WA 6007 TOWNSVILLE QLD 4810

PUCKRIDGE J T Dept. of Zoology, Univ. of SUCKLING GC Dept. of Conservation & Adelaide Environment GPO Box 598 5/240 Victoria Pde ADELAIDE SA 5001 MELBOURNE VIC 3002

PULLEN G Marine Laboratories SUTTON CA Centre for Marine Sciences Div. of Sea Fisheries Univ. of NSW P.O. Box I TAROONA TAS 7053 KENSINGTON NSW 2034

REICHELT R Bureau of Resource Sciences SWALES S Fisheries Research Institute P.O. Box El I, Queen Victoria Tee, P.O. Box 21 CANBERRA ACT 2600 CRONULLA NSW 2230

RICHARDSON B A NSW Fisheries TAY HC Centre for Marine Sciences P.O. Box 4805 ST. Univ. of NSW P.O. Box I LEONARDS NSW 2065 KENSINGTON NSW 2034

ROBERTSON J Great Barrier Reef Marine Park THORNCRAFT G A Fisheries Research Institute Authority P.O. Box 21 P.O. Box 1379, CRONULLA NSW 2230 TOWNSVILLE. QLD 4810 TRENDALLJ West Beach Aquaculture Pty. Ltd. ROWLING KR Fisheries Research Institute P.O. Box 559 P.O. Box 21 GLENELG SA 5045 CRONULLA NSW 2230 UNMACK P 161 High St RUSSELL DJ Nthn Fisheries Centre. Q.D.P.I. DONCASTER VIC 3108 P.O. Box 5396 VANCE DJ CSIRO Division of Fisheries CAIRNS QLD 4870 P.O. Box 120 SADDLIER SR Arthur Rylah Institute CLEVELAND QLD 4163 123 Brown St. WALKER TI Marine Sciences Laboratories HEIDELBERG VIC 3084 P.O. Box I 14, SHEPHERD MA School of Biol. Sciences, QUEENSCLIFF VIC 3225 Macquarie Univ. WHITE GF Dept. Primary Industry & NORTH RYDE NSW 2109 Fisheries SHEPHERD S A Sth. Aust. Res. & Dev. Inst.- P.O. Box 990 Fisheries DARWIN NT 0801 GPO Box 1625 WINSTANLEY RH Marine Sciences Laboratories ADELAIDE SA 5001 P.O. Box I 14, SMITH DC Marine Sciences Laboratories QUEENSCLIFF VIC 3225 P.O. Box 114, CSIRO Division of Fisheries QUEENSCLIFF VIC 3225 YOUNG PC GPO Box 1538 STANIFORD A J Office of Energy Planning HOBART TAS 7001 30 Wakefield St ADELAIDE SA 5000

STAPLES D Bureau of Resource Sciences P.O. Box El I, Queen Victoria Tee, CANBERRA ACT 2600

234 Bureau of Resource Sciences Proceedings