History, Status and Future of Oyster Culture in Australia

No.19

The 1st International Oyster Symposium Proceedings History, Status and Future of Oyster Culture in Australia

Greg B. Maguire1* and John A. Nell2

1.Research Division, Department of Fisheries, Western Australia, PO Box 20, North Beach, WA 6920, Austra- lia. 2.New South Wales Department of Primary Industries, Port Stephens Fisheries Centre, Private Bag 1, Nelson Bay, NSW 2315, Australia * Corresponding author Email: [email protected]

INTRODUCTION stract for the 1st International Oyster Symposium). Oyster farming is one of the oldest aquacul- Smaller quantities of Sydney rock oysters and the ture industries in Australia, dating back some 120 closely related Western rock oyster are grown in years (Nell, 2005). While farming methods, par- Queensland and Western Australia respectively. At ticularly for Sydney rock oysters, changed little times there has been some production of native fl at for several decades in the twentieth century, the oysters (Ostrea angasi) and native tropical oyster Australian industry in recent decades has been a species, chiefl y blacklip oysters (Striostrea mytiloi- very dynamic industry with new farming areas and des) and milky oysters (Saccostrea cucullata). additional Australian states becoming involved in Excluding Western Australia, the total value of oyster production while some traditional farming Australian edible oyster production was A$71.8 areas have experienced long term declines (Smith million for the 2003-04 financial year (ABARE, and Maguire, 1988). Additional changes include 2005). Most sales are for the high value, half shell the commissioning of oyster hatcheries, industries market rather than just as bulk sales of shucked based on exotic oysters progressively becoming oyster meat. This total production of over 13,000 larger than those based on native oyster species, tonnes is considerably higher than the 1999-2000 new environmental challenges being met, and bet- financial year estimate provided by Nell (2001) ter technology being developed by farmers, compa- who indicated total production of about 9,000 nies and researchers. For earlier reviews of oyster tonnes. The most dramatic growth in production farming industries in Australia see Holliday et al. has occurred in the South Australian industry. Oys- (1988), Maguire et al. (1988), O’Meley (1992), ter production in NSW has been relatively static Nell (1993, 2001, 2002a, 2005), Holliday (1995), in recent years and has not returned to its peak of Brown et al. (1997), and Love and Langenkamp about 8,400 tonnes in the mid 1970s (Nell, 2001) (2003) several of whom provide useful photo- or 9267 tonnes if production of Sydney rock oys- graphs. ters in Queensland is included (Nell, 1993). In Australia, oysters are sold by number eg per PRODUCTION STATISTICS dozen, and not by weight although different size The major industries for edible oysters in Aus- categories attract different prices per dozen. Re- tralia are based on production of native Sydney gardless, the above data imply that Pacifi c oysters rock oysters (Saccostrea glomerata) and introduced grown in South Australia are more valuable per kg Pacifi c oysters (Crassostrea gigas). The major ar- than Tasmanian Pacifi c oysters. This is not neces- eas of production, based on 2003-04 fi nancial year sarily the case. Industry sources suggest that the data (ABARE, 2005), are New South Wales NSW value estimate is a better indicator of the size of the (approximately 6000 tonnes worth A$37.9 million Tasmanian industry than the tonnage estimate. predominantly Sydney rock oysters but with 5% of total value from Pacific oysters), South Australia SYDNEY ROCK OYSTERS (4,382 tonnes worth A$21.2 million, almost all as Taxonomy Pacifi c oysters) and Tasmania (3,243 tonnes worth At the 1st International Oyster Symposium it was A$12.0 million, almost all as Pacifi c oysters). (1A$ apparent that there was some confusion over the = about 83 Yen at time of preparation of the ab- appropriate nomenclature for Sydney rock oysters. Oyster Research Institute News No.19

It was known for many years as Crassostrea com- ing of oysters at harvest (O’Meley, 1992; Nell, mercialis. In a review of oyster taxonomy in 1971 2001, 2002a). These are initially arranged in three- it was incorrectly considered to be Saccostrea dimensional bundles of fi ve layers of 20 sticks to cucullata, which is in fact the tropical milky catch spat, with the layers helping to deter preda- oyster (Nell, 2001) and dual usage of the two sci- tors, and are then nailed out in single layers of 20 entific names occurred eg Wisely et al. (1979). sticks for growout. The appropriate choice of in- Subsequently, the Sydney rock oysters was again tertidal height also assists with reducing losses due considered to be of the genus Saccostrea and the to winter mortality (Bonamia roughleyi) and some name Saccostrea commercialis was used by many farmers raise the intertidal growing height in win- authors eg Holliday et al. (1993). The similarity ter (Smith et al., 2000). Oysters, detached from the between Sydney and New Zealand rock oysters led sticks but too small for sale, can be grown to larger to their being considered as subspecies (Buroker sizes in large, intertidal trays. A range of alterna- et al., 1979) and Holliday (1995) proposed that the tive substrates to tarred sticks and trays were de- Sydney rock oyster be called Saccostrea glomerata veloped (Holliday et al., 1993; Nell 2001). The use commercialis. Because of the genetic similar- of tar and tar pits for coating wooden surfaces has ity of the Sydney and New Zealand rock oysters, become less acceptable from an environmental per- as indicated by DNA sequencing (Anderson and spective and many farmers now catch spat on plas- Adlard, 1994), the name Saccostrea glomerata is tic slats (2-3 mm thick, 104 mm wide) (Holliday et now widely used for both Sydney and New Zea- al., 1993). Increasingly, the oysters are detached land rock oysters eg Nell (2002a). The specific as spat, and grown in enclosed mesh trays and then name glomerata had been used prior to the name in baskets or mesh cylinders developed interstate commercialis for Australasian rock oysters and for Pacifi c oysters (see below). hence it was, by taxonomic convention, preferred. Modern subtidal growout systems were also The importation of New Zealand rock oyster spat introduced. Interestingly, given the hosting of the around 1888 to replenish depleted Sydney rock 1st International Oyster Symposium in Japan, these oyster stocks (Nell, 2001) may have contributed to subtidal systems evolved from initial work using the genetic similarity. Japanese techniques (scallop shells with oyster spat attached were separated by spacers on longlines Historical development of production systems (Wisely et al., 1979). Subsequently, in the limited Collecting and farming of Sydney rock oysters number of locations that can be used for multi- have a long history in Australia (Nell 1993). In- layer subtidal culture, a range of cage and stacked digenous Australians fi shed for both Sydney rock tray systems evolved (Holliday et al., 1988). A sub- oysters or flat oysters, depending on locality, and tidal system, called a pontoon, uses long, capped, middens (collections of old shells presumably ac- PVC pipes for fl otation and supports a single layer cumulated after removal of meats) for these spe- of oysters below. It has become popular in the key cies occur widely along the Australian coastline. farming area of Wallis Lake about 65 km north of After European settlement, Sydney rock oysters Port Stephens (Fig. 1). Given the use of intertidal were collected from rocks and mangroves in NSW baskets and cylinders and subtidal cages and trays, the 19th century and were often just for lime (cal- there has been a major shift to single seed culture cium carbonate) production. Middens were also (the farming of unattached oysters typically con- excavated for this purpose. Dredging for oysters tained within mesh containers). occurred and specifi c rock and shell bed areas were established for oyster production. Other diseases and genetic strategies The combined effects of siltation and mudworm Apart from mudworm and winter mortality, the commensals (spionid polychaetes especially Poly- latter of which usually affects oyster farms in the dora websteri – see Skeel, 1979) forced farmers to southern half of NSW through to the Victorian bor- develop off-bottom, timber post and horizontal rail der, the major biological problem has been QX dis- intertidal systems (racks). These supported vari- ease (Marteilia sydneyi). This paramyxean proto- ous types of horizontal timber oyster sticks with zoan can cause very high losses in warmer months tarred hardwood sticks (25 mm x 25 mm x 1.8 m) in the northern half of NSW and further north in becoming the preferred material. The tar inhibits southern Queensland. It appears to affect the host’s shipworm (Toredo spp.) and assists with detach- defence mechanisms by inhibiting enzyme (pheno- No.19

loxidase) activity (Peters and Raftos, 2003). Unfor- induction in bivalves become available. tunately, its impact has spread further south in re- It is important to note that that Pacific oysters cent years and has contributed to a severe reduction have become established in NSW but it was not in oyster farming in areas around Sydney (120-180 through introductions approved by the NSW gov- km south of Port Stephens). (Note that the oyster ernment. While they have the advantage of grow- diseases discussed above do not affect consumers ing much faster than Sydney rock oysters and are of oysters.) Predators can cause signifi cant losses resistant to some of the above diseases, spatfall of Sydney rock oysters grown in systems that are of this exotic species is considered undesirable in not fully enclosed by mesh that can exclude preda- NSW estuaries from a conservation perspective. tors such as fl atworms, fi sh and crabs (Nell, 1993). High levels of spatfall on farmed oysters are also Most Sydney rock farms have relied on wild undesirable from husbandry and marketing per- caught spat, traditionally from Port Stephens, al- spectives and, while techniques are available for though hatchery produced oysters have allowed killing the overcatch, they increase labour costs for lines of Sydney rock oysters that are selective (Nell, 2005). bred for growth rate and resistance to QX disease While triploid, or selectively bred, or triploid, (Nell and Hand, 2003). This breeding program selectively bred Sydney rock oysters may be use- has been based on mass selection and fortunately ful in helping to restore oyster industries around genetic diversity has been conserved well through Sydney, farmers in these areas will further evalu- the use of large numbers of broodstock initially ate “natural triploid” Pacific oysters as supplies used to create the mass selected line (English et al., from Tasmania increase. An additional advantage 2001). Growth rate has continued to improve with of “natural triploid” oysters is the minimal risk of successive generations and growout time has been spatfall because of greatly reduced gonad produc- reduced by 11 months (Nell and Perkins, 2005a). tion and likelihood of viable offspring when all of Survival rate, in response to exposure to QX dis- the oysters are triploids (Nell, 2002b). ease, has also improved greatly with each generation (Nell and Perkins, 2006). Profi tability Chemically induced, triploid Sydney rock oys- While Pacifi c oyster farming can be very profi t- ters (3N; three sets of chromosomes per cell in- able (see below for Tasmania), some less widely stead of two), also produced in hatcheries, confer available economic analyses have cast doubt on improved resistance to winter mortality (Hand et the profitability of more traditional Sydney rock al., 1998) and grow faster than diploids, although oyster farming methods (Holliday et al., 1988; this advantage varies with farming site (Nell, Maguire et al., 1988). Clearly, losses due to disease 2002b). However, as with triploid Pacific oysters are a serious problem, as is the slow growth rate of (Nell and Perkins, 2005b), there can be meat disco- this species (3.5 years to 50 g size for unselected, louration problems at times (Hand and Nell, 1999; diploid Sydney rock oysters in intertidal culture Nell 2002b). In contrast to Pacifi c oysters, “natural in NSW (Nell, 2001) compared to 17-18 months triploid” Sydney rock oyster production, achieved from spawning for diploid Pacifi c oysters in inter- by obtaining sperm (2N) and eggs (1N from fe- tidal culture in Tasmania (Maguire et al., 1994)). male after meiosis) from tetraploid (4N) and dip- The choice of production system may also be in- loid (2N) lines respectively (Guo et al., 1996), has fluential. Growing Sydney rock oyster on sticks not been successful because of the lack of success is a relatively low yielding farming system, partly with producing tetraploid lines. This is despite the because of variable coverage of sticks by oysters, wide range of techniques that were assessed with whereas standing crop may be at least double with Sydney rock oysters (Nell et al., 1998). One of the the use of single seed Pacific oysters in baskets, problems is the low number of high quality eggs at least in Tasmania. This estimated difference is produced by chemically induced triploid Sydney based on data in Maguire et al. (1994) and also rock oysters. “Natural” triploids are almost all trip- from Holliday et al. (1988) who estimated yields loids, as opposed to a mixture of triploid and dip- for a range of production systems including culture loid individuals as occurs with batches of chemi- of Sydney rock oysters on hardwood sticks, i.e. cally induced triploids. This is a major advantage 5-8 kg of whole oysters per m2 of oyster rack area and further work should be undertaken with Syd- in two years. Because single seed techniques allow ney rock oysters as new techniques for tetraploidy adjustment of density through the production cycle, Oyster Research Institute News No.19

lease space can be more efficiently utilised than has involved classification of waterways and not with growout on sticks. The latter technique re- just reliance on land-based oyster depuration tech- quires relatively little labour input, after the sticks nology (Nell 2002a). Oysters can also be relocated are rearranged as single layers on intertidal leases, to “cleaner” fi nishing sites within estuaries but this until harvest. However, processing clumps of oys- increases costs. These developments should en- ters into marketable individual oysters as whole gender greater public health confi dence in the con- oysters or in the half-shell is labour intensive. sumption of Sydney rock oysters produced in NSW There is an ongoing need to promote this small and promote exports. In a major literature review oyster as a gourmet product and to maintain high by C. Burke and G. Maguire in 1998, which was product standards. However, the tendency towards further developed by Jackson and Ogburn (1999), sales of smaller size grades of Sydney rock oysters the key conclusion was that bacterial indicators is of concern to the NSW industry because it can eg E. coli, are not necessarily good indicators of reduce profi tability (Nell, 2005). viruses that are pathogenic to humans. While viral monitoring is carried out in NSW, the development Hatchery issues of more cost-effective techniques for monitoring Some of the technical innovations (triploidy and specifi c viruses, including Nowalk virus and hepa- selective breeding) should help greatly with profi t- titis A viruses, is a worldwide challenge. ability however they rely on hatchery production. The Sydney rock oyster industry in NSW is still Environmental issues heavily reliant on natural spatfall and the hatchery The Sydney rock oyster is a robust species in sector has struggled to produce this species reli- terms of environmental tolerance but can be vul- ably because of anorexia in 2-8 day old larvae nerable to extended exposure to very low salinities and sudden gaping and death of spat below 2 mm (to less than 10 ppt for 2 weeks) and acute expo- (Heasman, 2004). There has been some success sure to high air temperatures when out of water with producing Sydney rock oysters in a hatchery (Nell, 1993). As such, Sydney rock oyster farms in Queensland and the very closely related West- could be vulnerable to climate change although ern rock oyster in Western Australia (WA) can be some researchers consider that the natural range produced reliably in a hatchery near Albany on the of this species extends north through tropical areas south coast of WA. Fortunately, there has been re- of Australia (Nell, 2005). Changes in rainfall pat- cent success with large-scale hatchery production terns could also affect nutrient input into estuaries. of Sydney rock spat in NSW. The use of single Urbanisation of coastal areas can lead to a range seed culture systems for Sydney rock oysters may of other environmental changes including eutro- also improve profi tability and this is not necessar- phication and the associated risks of algal blooms. ily reliant on hatcheries. Fortunately, toxic algal blooms that impact on the health of consumers have been much less of Public health issues a problem for bivalve industries in Australia than As with many bivalve industries worldwide, in many other countries. Unfortunately, not all the Sydney rock oyster industry in NSW operated members relocating to coastal areas are favourably in many estuaries that experienced little human disposed to the perceived visual and navigational impact but which subsequently were subject to impacts of oyster farms and sea-based aquaculture coastal urbanisation. After serious cases of gastro- in general. enteritus occurred near Sydney that were linked with oyster consumption, land-based oyster depu- PACIFIC OYSTERS ration technology was introduced in the late 1970s. Origin of stocks In the 1980s and 1990s there were several episodes Pacific oysters were introduced Tasmania from of gastroenteritus caused by Nowalk virus associ- 1947-52 (from Sendai, Hiroshima and Kumamoto ated with oysters. In 1997 another major outbreak regions of Japan). Such introductions were unsuc- of gastroenteritus occurred which was linked to cessful in other Australian states and the industry hepatitis A and often was associated with con- expanded in northern Tasmania, based on natu- sumption of Sydney rock oysters. A shellfi sh qual- ral spatfall. There are still locations in Tasmania ity assurance program was formally implemented where Pacific oysters have become naturalised, later that year (Jackson and Ogburn, 1999). This periodically setting on rock structures even though No.19

commercial farms are not operating in those ar- inder design have emerged and the technology has eas. Deupree (1993) concluded that deep-cupped been introduced to most Australian oyster produc- Pacifi c oysters in Tasmania were not derived from ing states. These Tasmanian and South Australian Kumamoto strain oysters (C. sikamea). However, systems are lightweight and allow oyster boats to English et al. (2000) showed using allozyme tech- be loaded with large numbers of baskets or cylin- niques that nine groups were very similar geneti- ders for grading or sale of oysters on-shore. cally. These included four naturalised groups, three of which were Tasmanian and one was from Diseases and genetic strategies Port Stephens, three hatchery-derived groups from Pacifi c oyster farming has been particularly suc- Tasmanian farms and two groups obtained from cessful in Tasmania and South Australia largely Sendai and Hiroshima in Japan. These results were because of the absence of significant diseases. confirmed by English (2001) using microsatel- Apart from sacrificial sampling, overall mortality lite techniques. Overall, the results confirmed the of diploid and triploid Pacifi c oysters at two good origin of the Tasmanian stocks and indicated that farming in Tasmania were <1% during the 22-23 sound hatchery practices had allowed the Tas- months the oysters were held in intertidal mesh manian industry to avoid major losses in genetic baskets (Maguire et al., 1994). Losses can occur in diversity. It is likely that the deep-cupped shape of nursery systems if overcrowded or if food levels in many Tasmanian Pacifi c oysters partly refl ects the the seawater supply are severely limiting. (Saxby, high degree of shell abrasion that occurs during 2002 reviewed food availability at bivalve farm- grading of oysters on vibrating or rotating screens ing sites internationally, including at Pacifi c oyster during routine stock management of single seed farms in Tasmania and South Australia.) Losses, by oysters (O’Meley, 1995). displacement or to predators, can be minimised by placing a cover over the top of open baskets or by Development of production systems complete enclosure of oysters within the cylinders Because natural spatfall did not prove to be reli- or tubes. able, the Tasmanian industry moved to a hatchery- Pacifi c oyster farming in Australia have benefi ted derived spat supply and new growout areas about from selective breeding programs involving mass 25 years ago (Ward et al., 2000). Modern produc- selection for faster growth and use of family lines tion in Tasmania is based on single seed oysters (Maguire, 1997a; Ward et al., 2000; Thompson and produced, by relatively standard international Ward, 2004). Progress has also been made with full techniques, in indoor larval tanks and then in land- sib crosses (to remove deleterious recessives) and based upwellers before being moved into intertidal, with using microsatellites to help interpret perfor- plastic mesh nursery trays. Growout is typically mance of family lines (McGoldrick et al., 2000). within units of two plastic mesh, open baskets The results of much of this research program have supported by two timber stakes that pass through been commercialised and while initial demand was the length of both baskets. The sticks are then ar- highest for mass selected oysters, farmers are now ranged across intertidal post and rail systems (Nell, more inclined to purchase specifi c family lines (R. 2002a) and are secured with strong rubber ties than Pugh, pers. comm. 2004). can be easily detached for stock management. Sig- Research on triploid Pacifi c oysters in Tasmania nificant quantities are also grown out in subtidal and South Australia was aimed primarily at inhibit- cage systems. Subsequently, spat were provided ing spawning so that the oysters remained saleable to South Australian farmers and a Pacific oyster in summer months. This was achieved with chemi- industry was established in South Australian with cally induced triploids although the more rapid government approval, and has outgrown the indus- shell growth of triploid oysters after they reach try in Tasmania. A significant innovation was the about 60 mm in Tasmania can reduce meat weight “horizontal longline” system in which tensioned to shell cavity volume ratio (condition index) wire replaced timber rails on intertidal leases and (Maguire et al., 1994). There have been examples enclosed individual plastic mesh tubes or cylinders of large growth rate advantages of triploid oysters were hung from a single wire with two simple, of various species (31-81%), often commencing at detachable clips (see Nell, 2002a). This allowed sizes much less than 60 mm (Nell, 2002b). How- farming in areas where wave action was excessive ever, the growth advantages at the two better sites for more traditional systems. Variations to the cylin Tasmania were only 23.4%, on a whole weight Oyster Research Institute News No.19

basis, at age 27-28 months (Maguire et al., 1994). O’Meley (1992) indicated that Pacifi c oysters may Subsequently, no growth advantage was recorded be graded 5-7 times during growout in Tasma- at one site in South Australia (Ward et al., 2000). nia (excluding grading operations in the nursery Meat discolouration can be an occasional problem phase). Reducing the frequency of size grading with triploids in Tasmania. should lower production costs for Pacific oysters The development of “natural triploids” has led as grading operations, including moving oysters to increasing demand for triploid Pacific oysters. to and from leases, are labour intensive and labour Tetraploids produced by the first author, using costs are highly significant to the economics of techniques developed by Guo and Allen (1994), oyster farming in Tasmania (Treadwell et al., 1991; have been used for several years in Tasmania to Maguire, 1993). While selectively bred or triploid produce “natural triploids” but fortunately a new spat attract a price premium, better performance of tetraploid line has now been produced there, using these oysters should also assist with maintaining eggs from “natural triploids”, to help replace this profi tability. ageing line of tetraploids. Moreover, there has also been success in Tasmania with a tetraploid x tetra- Hatchery issues ploid cross to produce another tetraploid line (G. In contrast to NSW, Tasmania now has more Kent, pers. comm. 2005). Interviews with oyster than adequate hatchery capacity particularly with farmers in Tasmania and South Australia indicate the move towards smaller, high density, flow that they prefer the natural triploids because of through larval rearing systems. Increased demand the almost 100% triploidy level and ongoing suc- will largely be for genetically selected lines and cess with avoiding spawning in summer but again natural triploids. In contrast to some Pacifi c oyster growth rate advantages with triploids were con- hatcheries overseas, it has not been necessary to sidered to be relatively small. In contrast, Nell and rely on antibiotics in Tasmanian hatcheries. Perkins (2005b) obtained “natural triploid” Pacifi c spat from Tasmania and achieved high growth and Public health issues survival rate advantages in Port Stephens. These In contrast to NSW, the relevant coastlines of spat reached 55 g whole weight in 13 months in- Tasmania and South Australia are not very heav- stead of 20 months with unrelated diploid Pacifi c ily urbanised and these states have had few public oysters. It seems likely that a combination of warm health problems due to oyster consumption. They water temperatures and adequate food supplies rely on oyster growing area classifi cation and ap- is necessary to achieve a large growth advantage propriate closures after substantial rainfall rather with triploid Pacific. Meat discolouration again than land-based depuration systems. occurred but the “natural triploid” Pacific oysters reached market size before this was evident (Nell Environmental issues and Perkins, 2005b). In terms of impacts of the environment on oysters, “heat kill” can occur particularly on South Profi tability Australian leases if hot weather coincides with Pacific oyster farming can provide an excel- very low tides. Some leases in Tasmania had to be lent and highly predictable return on capital (27% relocated because of extended exposure to fresh- per annum) at good farming sites in Tasmania water after heavy rainfall. (Treadwell et al., 1991). Subsequently, marketing The environmental impact of oyster farming in pressures have been placed on Tasmanian farmers Tasmania and South Australia has not been a major because of the rapid growth in production of Pacif- problem although not all community members are ic oysters in South Australia. Increased exports of comfortable with perceived visual and navigational Australian oysters would assist the domestic mar- impacts of oyster farms (Maguire, 1992). Pacific ket and South Australian Pacifi c oysters are being oyster spatfall has at times been contentious in Tas- exported to Japan during the northern hemisphere mania but in general the degree of “overspatting” summer. in much lower than in NSW. While some spat do Earlier research by the fi rst author showed that it develop on oyster cylinders in South Australia, it is was not necessary to grade oysters so often to pre- generally a very minor problem in these hypersa- vent excessive size variation (Maguire, 1997b) and line areas. Intertidal culture in Tasmania does lead this is being adopted by some farmers in Tasmania. to biodeposition of organic wastes on the seabed. No.19

Attempts to grow venerid clams below the oyster around Sydney, efforts be made to rejuvenate them. racks, as a way of minimising organic buildup, Finally, the ongoing commitment to public were unsuccessful (Maguire, 2005). To meet Aus- health and product quality standards with Aus- tralian government requirements for export, both tralian oysters is important both for promoting Pacific oyster industries have to demonstrate that exports and for encouraging younger consumers in they meet sustainability principles (Fletcher et al., Australia to purchase oysters so that the domestic 2004). market remains strong.

OTHER ISSUES FOR OYSTER FARMING IN ACKNOWLEDGMENTS AUSTRALIA The authors are grateful for information supplied Forms of aquaculture that use inshore coastal by oyster industry staff in Australia. Mr Kunio waters do attract criticism from communities and it Shirasu kindly arranged access to information from is important that these industries minimise environ- oyster buyers at the Tokyo Fish Market. mental impact. For example, quality assurance programs for bivalve aquaculture industries in Western DEDICATION Australia require shoreline surveys to ensure that This paper is dedicated to the outstanding con- farming debris, such as displaced oyster baskets, is tributions made by the late Drs Baughan Wisely not evident. and John Holliday. They and several other key Conversely, it is also appropriate to highlight the researchers played major roles in making the re- benefi ts associated with these industries. Typically, search facility, currently known as the Port Ste- these are economic and social benefi ts that accrue phens Fisheries Centre, one of the world’s major from increased employment and investment. In the oyster husbandry research centres for over 30 case of oyster farms there are additional environ- years. mental benefi ts. At least in Australia, where quality assurance programs require monitoring of oyster REFERENCES growing areas for a range of attributes including ABARE, 2005. Australian Fisheries Statistics water quality and types of phytoplankton, oyster 2004. Australian Bureau of Agricultural and Re- leases represent one of the most signifi cant sources source Economics, Canberra, Australia, 65p. of estuarine water quality monitoring. This can be Anderson T.J. and Adlard R.D., 1994. Nucleotide augmented by periodic checks on any heavy metal sequence of rDNA internal transcribed spacer or pesticide contamination in seafood (not a sig- supports synonymy of Saccostrea commercialis nifi cant problem so far with oysters in Australia). and S. glomerata. Journal of Molluscan Studies, As bioaccumulators of contaminants, oysters are 60: 196-197. sentinels for any estuarine pollution. Moreover, Avery, E.L., Dunstan, R.H. and Nell, J.A., 1998. oyster farmers visually inspect their oysters quite The use of metabolic profiling to assess the regularly and poor growth or unexpected mortality biological impact of marine sewerage pollution. can be observed and investigated. Some years ago Archives of Environmental Contamination and in NSW, chambering in oyster shells highlighted a Toxicology (New York), 35: 229-235. problem with tributyl tin from antifouling paints on Batley, G.E., Fuhua, C., Brockbank, C.I. and boats (Batley et al., 1989). This led to restrictions, Flegg, K.J., 1989. Accumulation of tributyltin by on the use of such paints, that probably also ben- the Sydney rock oyster, Saccostrea commercia- efited non-commercial bivalve species. It is clear lis. Australian Journal of Marine and Freshwater that oyster farmers can be effective lobby groups Research, 40: 49-54. for environmental protection (Maguire, 1991). In Brown, D., Van Landeghem, K. and Schuele, M., the absence of oyster farms, oysters, which are 1997. Australian aquaculture: Industry profiles not subsequently released for human consump- for selected species. ABARE Research Report tion, have been deployed in NSW specifi cally for 97.3, Canberra, Australia, 102p. environmental monitoring purposes (Avery et al., Buroker N.E., Hershberger W.K. and Chew K.K., 1998). 1979. Population genetics of the family Ostre- Given the environmental protection role that idae: I. Intraspecifi c studies of Crassostrea gigas oyster leases can have, it is important that where and Saccostrea commercialis. Marine Biology, oyster industries have declined in waterways 54: 157-169. Oyster Research Institute News No.19

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Fig. 1 Map of Australia showing some of the individual oyster growing areas where triploid oyster research has been undertaken by the authors.