Smith Bxeeuti ve Summary physiological changes associatedwith Japaneseflounder metamor- phosis were documented Tanaka!. A general biology session included two papers. The Bechtol paper addressedbiological characteristics of three abundant species in Kacheinak Bay,Alaska. The Meyer paper discussed characteristics of the southcentral Alaska sport fishery and alluded to potential conflicts between commercial and sport fisheries. Nine papers addressed feeding and growth of in session four. Four papers Yang, Lang, Chilton, and Yokoyaina! dealt with food habits and diet overlap. The Chilton and Yokoyama papers reported on single-species feeding habits, while the Yang and Lang papers exam- ined diet sitnilarity and diet overlap ainong several species.Otoliths were the focus of two papers; Blood compared age reading techniques on otoliths, and Hagen examined inicrostructures and their deposition patterns in halibut. The three remaining papers addressed different aspects of food and energy requirements in three different flatfish species: brawn sale Toininaga!, yellowfin Smith!, and flathead sole Paul!. Session five was on abundance, and distribution and consisted of 10 papers, 8 of which were single species studies. Those specieswere: English sole Shi and Sampson!, Greenland Ianelli, Kodolov, and Vatulina!, Pacific halibut Kodolov and Hooge! and petrale sole Castillo!. Papers by McConnaughy and Ivankova dealt with rnultispecies populations. A session on pollution, parasites, and disease included four papers. Avoidance of hydrocarbons in sediments was discussed by Moles and contaminant effects on reproductive output was reported by Sol. Lesions and parasites were discussed by Smith while the utility of parasites as indicators of flatfish biological characteristics was described by Moles. Management and economics was the subject of the final session af contributed papers. Problems confronting the arrowtooth commercial fishery were described by Cullenberg. Mortality of Paciiflic halibut caught incidental to other fisheries was described and ana- lyzed by Trumble and Williains. The Witherall paper addressed man- agement of flatfish in U.S. waters. The last session was a discussion of future research needs, Partici- pants identified a list of topics that require further research activity. The areas identified could serve as a guide for further cooperation between the agencies and institutions represented at this symposium. Further, it cauld serve as a reference for future research funding priorities. Proceedingsof the InsernationalSymposium on Xorrh PaciP'cFlatfi'sh Alaska SeaGrani CollegeProgram ~ AK-SC-95-04,l995

Raffish Management in the EasternPacific Ocean with Special Reference to Pacific Halibut

Donald A. McCaughran International Pacific Hat but Commission Seattle, Washington USA

Abstract Commercial flatfish harvesting began in the eastern Pacific in the late 1800s,Several vessels began fishing for Pacific halibut on the coast of Washington and British Columbia in 1883.The fishery quicklyex- pandedto British Columbia and Alaska, and by 1920harvesting of BeringSea stocks had begun. Harvesting of other speciesof flatfish began later than halibut mainly due to the ease of fishing halibut with longlinefishing techniques. Most species of flatfish aretoo small to be caughtwith longline gear.lt was not until the arrival of the modern "trawler"that fishingfor the other species of flatfish began. Early in the 1900sseveral steam-driven "otter" trawlers were broughtfrom New England and tried unsuccessfully to trawl for halibut. These vesselsdid not develop fisheries for other species of flatfish but insteadturned to longlininghalibut. Later,diesel poweredtrawlers were built, and sporadic trawling beganfor species such as English andpetrale sole, but it wasnot until after the SecondWorld War that intensive fishing for other flatfish species developed. A brief discussion of the various flatfish fisheries is given, and sincePacific halibut have been harvested for a much longer time, and have received a higher level of research and management, a more thorough discussion wifl be presented for that species. McCaughran Flatfish Management in the Eastern Pacific Ocean

Table 1. Exploitedfiatfish speciesof the northeastPacific and easternBering Sea.

Common name Scientific name

Alaska Pleuronectes quadri tuberculatus Atheresthes stomias Butter sole Pleuronectes isolepis Dover sole Microstomus pacificus English sole inopsetra ischyra Flathead sole Hi p poglossoides elassodon Greenland turbot Reinhardrius hi ppoglossoides Longhead dab Pleuronectes proboscidea Pacific sanddab Ci tharichrhys sordidus Pacific halibut Hi ppoglossus stenolepis Petrale sole Fopserta j ordani Rex sole Errex zachirus Rock sole Pleuronectes bi lineatus Starry flounder Platichthys stellatus Yellowfin sole Pleuronecresasper

The Flatfish Resource The flatfish species that are currently being harvested in the eastern Pacific are given in Table 1. The estimated present 993! biomass and yield of each species is given for the eastern ,Gulf of Alaska, British Columbia, and the Washington-Oregon coasts Table 2! Fargo 1994,NPFMC 1994,PFMC 1994!.The yields of flatfish amount to 12% of the total Bering Seagroundfish yield, 27% of the Gulf of Alaska, 9% of British Columbia and 9% of the Washington-Oregongroundfish yield. This amountsto a significantimpact on the total economyof our North American fisheries. The ex-vessel value of Pacific halibut alone is approximately 130 million dollars annually. Only Alaska pollockexceeds flatfishes in economicvalue, The importance of flatfish will continue to grow since many species are not exploited at their full poteritia, we have barely begun to exploit arrowtoothflounder for example.The only speciesfully exploited are Pacific halibut and yellowfin sole in the Bering Sea, and petrale sole, Dover sole,and English soleoff the Pacific Coast.All other species are under-utilized,particularly in the Gulf of Alaska. Proceedingsof the international Symposiumon North Pacific Flatfish

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Strange as it might seem, to those not familiar with these fisheries, it is often the bycatch of Pacifichalibut that controls the yields of many of the other species.

Stockassessment and management Table 3 summarizes the methods used for stock assessment and harvesting strategy for most of the exploited flatfish species. Pacific halibut will be discussed in detail later because of its long history of exploitation and rnanagernent.Trawl surveys and catch at age analy- ses are the most cominon stock assessinent methods. Trawl surveys alone often give extreinely variable results, however when combined with age structure analysis satisfactory results can be obtained. The most coininon exploitation strategyused is the so-called Fss+ method developed by Dr. William Clark of the International Pacific Halibut Cominission Clark 1991!.Strangely enough, as we will see later, this method is not used for Pacific halibut. In addition, the older Fpi method is used with considerable successin British Columbia. Both the Fs5%and the Fp, inethods are largely empirical methods but seem to work quite well for many species. The test of any inethod is the "test of time." If "good" yields can be taken from a species over a long period of time and thereby creating stabilityin the supply side of the industry, then the method is deemed a "goodstrategy." The Fss+is relatively new in its deployment; only time will tell if this strategy combined with the current stock assessmentmethods produces a satisfactory inanagement and harvesting strategy.

Pacific Halibut Pacific halibut Hippoglossus sretiolepis! is the largest of the Pacific Ocean flatfishes. It occurs from northern California throughout the Gulf of Alaska and Bering Seaacross to the coast of Russiaand south to northern Japan. In the eastern Bering Sea and the eastern Pacific it has the longest history of exploitation and management of any of the flatfishes, Its exploitation and management structure therefore are worthy of a detailed description.

Historic catches Historically, the annual domesticyield of halibut has varied between 13,000 and 45,000 tons. The catches began with less than 100 tons in the 1880s and rose quickly to 40,000 tons by 1915 and dropped to 21,000 by 1918 Figure 1!. This drop in catches was a major concern Proceedingsof the international Symposiumon North Pacific Flatfish

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1940 1950 1960 1970 'I999 1 990

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Figure l. Historic halibut commercial catches.

for fishermen and created the demand for inanageinent, The Interna- tional Fisheries Commission was formed by the United Statesand Canadain 1923.With the onset of management and winter fishing closures the stockbegan to grow until a yield of 42,000 tons was reached in 1961.At that time groundfish fishing began by non- domestic vesselsand within severalyears these vesselshad an annual bycatch of halibut in the 15,000ton range, The large bycatch com- bined with high domestic catches at that titne resulted in a precipitous declinein halibut stocks.The commissionquickly reduced domestic catches and by the inid-1970s were the lowest in the modern history of the fishery 3,300 mt!. With the imposition of the U.S. and Canada 200 mile zones bycatch was finally controlled and by 1985the total bycatch was 3,200 tnt. Combined with reduced doinestic reinovals and a favorable environment increased survival!, in the 1980s, the stocks grew to a level that allowed a harvest of 45,000 tons in 1988. This has been followed by a natural downturn in recruitment and the stocks have decreasedto a levelthat now producea yieldof 34,500 tons. Proceedingsof the International Syrnposittm on WorthPacific FlatI!sh history of management Thirty yearsafter the fisherybegan the declinein catchesmentioned earlier prompted fishermen and processors to lobby their govern- ments for some type of research and inanagement program, The governments of Canada and the United States negotiated a treaty signed in 1923! to jointly investigate the causesfor the apparent decline in the stocks. The International Fisheries Coinmission was created and a staff of seven undertook a series of research projects to study halibut life history and to investigate the necessity of imposing catch restrictions on the fishery. In 1930the treaty was revised to allow the commission to restrict catches by area and time and to provide a forum with industry to annually promulgate fishing regulations. Further amendments to the treaty have been made from time to time increasing the commission's role in the conservation of the stocks.The commission was renamed the International Pacific Halibut Commis- sion IPHC! in 1953.The last amendment to the treaty was inade in 1979in response to the creation of the national 200 mile zones,The amendments continued the commission's conservation role and allowed the two national governments to allocate among domestic user groups providing the national regulations do not conflict with those of the commission.

Stock assessment Prior to 1960no scientifically based estimates of halibut biomass were attempted.Fortunately, the cotntnissionhad set up a datacollection system in the 1930sto sainple otoliths and logbooks from various ports over the range of the fishery. The logbook program was initiated to obtain estimates of effort and catch-per-effort. As stock assessinent methods developed, these long-term data sets became very useful. In the 1970sas population assessmentmethods developed the commis- sion began to use age structure data to estimate biomass. Cohort analysiswas the first methodused to providethe commissionwith estimates of biomass. The commission staff developed a computer program called "CAGEN" to implement catch at age data in its annual stock assessment. We use a modification of this method at present, The method produces annual estimates of exploitable biomass 8-20 years old! by region and re-estimates the past 13 years annual esti- mates as well, io McCaughran Flatfish Management in the Eastern Pacific Ocean

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1940 1950 1900 1970 1990 1990 Year

Figure 2, Historic halibtit CPUE and biomass.

Harvesting strategies Prior to 1975 the commission had no real scientifically based harvest- ing strategy, The commission had long data records of catch and effort. Yield recornrnendations were arrived at by trial and error, Yields were increased when catch per effort increased and were reduced when CPUE dropped. In retrospect this was not too bad an approach, since CPUE follows the stock biomass very well Figure 2!, The method was conservative and achieved a great deal of success as measured by a re-analysis of the older data to produce historic biomass estimates. In the 1960sthe commission used yield-per-recruit analysis and stock production methods to attempt to arrive at an estimate of maximum sustainable yield. The commission abandoned the strategy of managing the stocks to produce maximum sustainable yield 25 years ago and has investigated and employed a variety of different harvesting strategies since that time. In the 1970s, after the rapid decline in the stocks, an emphasis was placed on rebuilding the depressed biomass. With biomass estimates available from cohort analysis, a temporary strategy of setting yields at 75!o of the annual surplus production was used with success until 1984 when a tnore Proceedingsof the International Sytnposinmon ¹rth Pacif'icFlatfish scientific long term fishing strategy called constantexploitation yield was initiated. This method began by setting yields at 35% of the exploitable biomass ages 8-20!. The 35%was initially arrivedat by looking at the exploitablestock size that producedthe calculatedmaxirnuin sus- tained yield and recognizing that MSY was 35% of that value. This strategy has the desirable featureof having yields follow the natural cyclesin stock abundance caused by a soinewhat cyclic recruitinent pattern.The constantexploitation rate strategywas then subjectedto a greatdeal of analysisby computersimulation and wasfound to produce large long term yields while offering liule risk of over-fishing. The commission felt this strategy would serve the halibut industry bestby insuring a considerablemeasure of stability. In 1991further research on the exploitation rate was conducted, It was found that 0.30 resultedin a smallreduction in long term yield but gavea veryhigh assurancethat the spawningbiomass would not drop below the lowest recorded level. This additional measure while more conservative was considered to be desirable and the commis- sion adoptedit in 1992.We are at presentcomputing yields at 0.30of the exploitable biomass.

Bycatch Prior to 1960there was little bycatch of halibut in the fisheries for other species. Figure 3 shows the treinendousincrease in bycatch since that time, and documents the events which caused the increase. Non-doinestic trawlers were mainly responsible for the rapid increasein bycatch.The large and poorlydocumented bycatch began at a time when the commission was attempting to maximize catches from a stockin excellentcondition high level of abundance!.The high bycatch and high catches coincided with the natural downturn in the recruiunentcycle. The combinedresult of thesefactors caused the stocks to drop to very low levels in a very short period of time. The official documented maximum bycatch by the non-domestic trawl fleet was 15,000tons, IPHC believesthe maxiinum bycatchoccurred in the late 1960sand was probably in the 20,000 ton range.With the creation of the 200 mile zones in the United States and Canada bycatchcontrols were placed on the foreignfleets and bycatchde- clined to 3,200 tons by the mid-1980s. As the foreign fleets were replacedby a domesticfleet bycatchagain increaseduntil protests from the halibut industryand IPHC caused bycatch caps to be im- posed.At presentthe bycatchis cappedin the BeringSea and Gulf of 12 McCaughran Flarfish Managemenrin rheEasrern Pacific Ocean

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Alaska,but not in British Coluinbiaand the Washington-Oregon fisheries, The presenttotal bycatchis approximatelyl0,000 tons. The lPHC compensates the halibut stocksfor the reproductive lossfrom bycatchby reducingthe domestic commercialcatch by the total amount of bycatchand allocates the reductionson a regional basis proportional to the biomassof halibut in each region. The IPHC believesthat the bycatch is higherthan necessaryto prosecute the groundfish fisheries in both the United States and Canada.The high bycatch is causedby too many fishingvessels fishing for groundfishwhich in turn causesa "race"for and a disregard for selectivefishing practices. Reductions in bycatch will only be brought about by an incentive programsuch as an individual vessel bycatch quota systein.

The fishery The first 75 years of the north American halibut fishery was very stable. 1n total there was less than 1,500vessels participating in the Proceedingsof the International Symposiumon lvorth Pacific Flatfish i3

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77 78 79 80 8i 82 83 84 85 86 87 88 89 90 9i 92 Year Figure 4. Aumber offishing days and catch in Area 3A central Alaska!.

fishery. Beginningin the mid-1970sand continuinginto the 1990sa largeincrease in the number of vesselsoccurred. This increase occurred mainly in Alaska. The result was fewer and fewer fishing days. Figure 4 shows the number of fishingdays in Area 3 central Alaska! and the catch from 1977 to 1992.The fishery is now completed in two 24-hour fishing periods. The total yield is 35,000tons. This is spreadover the variousmanagement areas proportional to the biomassin each area. The commissionhas adoptedthe strategyof subdividing areas whenever it is determinedthat unequal exploitation rates are occurring in a large area. Over the past 15 yearsa sizable sport fishery for Pacific halibut has developed, partially in response, in some areas, to reduction in salmonstocks. The sportsfishery has grown into a profitablebusiness in many areas of the coast and the 1993removal by sport fishermen was approximately 4,000 tons. As previously mentioned, the total allowable catch by area is computedas 0.3 x exploitablebiomass in each area. Once these estimates are obtained bycatch, sports catch, wastage causedfrom lost gear,and juvenilehandling mortality are subtractedand the McCaughran Flatfish Management in the Eastern Pacific Ocean

Sport Ca Personal Use Mortality 8.2%!

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Commercial Cate Ft'gure 5, Halibut removals P om various sources in 1993.

remainder allocated to commercial halibut fishermen. Seasons are computed which do not allow overagesin catch to occur and, if necessary,trip limits by vessel size are imposed. Figure 5 shows the removals from the various sources.In Area 2A Washington, Oregon! further allocation is done by the U.S. government to sports, commer- cial, and native Indian treaty tribes. In Area 2B British Columbia! the Canadian government further allocates to each vessel in an individual fishing quota system. The Canadian fishery is open from March I to October 31 and quota holders fish any time during that period, The Canadian catch inainly goes to the domestic United Statesand Canada! fresh market and brings the highest price $2.50-2.80per pound U.S.!. In 1995 the United Stateshopes to irnpletrierit an individual vessel quota system as well. Their vesselswill also fish from spring to fall. This systein will bring order, safety, and consolidation to the U.S, fishery, and make the management of the fishery easier. These changes create a more professional and responsible fleet with a stronger interest in conservation. Since the U.S. system also applies to sablefish there should be a reduction in the halibut bycatch in the sablefish fishery. These savings will then be passed onto the halibut/sablefish fleet directly. Proceedingsof the International Symposiam on Xorrh Pacific Flatfis 15

The future As previously indicated, the fishery will change dramatically with the advent of individual vesselquota systems.These changes will improve the prosecution and management of the fishery considerably. The economic value of the fishery will increase with a larger proportion of the catch being sold fresh, With a more coniplete log book system, and with better navigation GPS!we hope to be able to refine the level of management. We anticipate using spatial statistical methods to get more precise estimates of CPUE by area. This will improve the bio- mass estimates as well as improving allocation by area, Continual analysis of different harvesting strategies may find better methods of computing harvest levels. If the U.S. government can create a system of individual bycatch quotas for its groundfish fleet we expect to see reductions in bycatch in the future, allowing inore harvesting by the dotnestic halibut fleets, The IPHC has enjoyed considerable successin the past in manag- ing this valuableresource. We feel the future may proveto be even more successful.

References Bell, F.H. 1981. The Pacific halibut, the resource and the fishery, Alaska Northwest Publishing Co., Anchorage, Alaska, Clark, WG. 1991, Groundfish exploitation rates based on life history parameters. Can. Jour. Fish and Aquatic Sci. 4Bl:734-750, Fargo,l. 1994,Flatfish stock assessinentfor 1994and recoininendedyields for 1995. D.F.O.Bio. Sci, Branch Report, Pacific Biological Station. North Pacific Fishery Management Council NPFMC!. 1994. Stock assessment and fishery evaluationreport for the groundfish resourcesof the Gulf of Alaskaas projected for 1994. North PacificFishery Management CounciL 1994.Stock assessment and iishery evaluation report for the groundfish resourcesof the BeringSea/Aleutian Islands region as projected for 1994. Pacific Fishery ManagementCouncil PFMCL 1994.Status of Pacific Coast groundfish fishery through 1993and recommendedacceptable biological catches for 1994. Portland, Oregon.