Executive summary

Capture-based aquaculture is a global activity but has specific characteristics that depend on geographical location and the species being cultured. The species groups used in capture-based aquaculture include molluscs (e.g. oysters, mussels, scallops), crustaceans (e.g. shrimps, crabs) and finfish (e.g. eels, grey mullets, milkfish, yellowtails, groupers, rabbitfish, tunas). The scale of such practices is difficult to quantify, but it is estimated that about 20 per cent of aquaculture production comes from capture-based aquaculture.

The total value of the farmed production of the four species groups considered in this report (the figures reported to FAO are believed to be underestimates) in 2000 alone exceeded US$ 1.7 billion.
This report focuses on four species that show high market demand and value and have a short grow out time to market size – eels, yellowtails, groupers and tunas. A description of the rearing, harvesting and marketing practices for each species is provided, together with a review of environmental, social, economic, food safety and management issues. The following are the major findings:

? Seed supply: no suitable commercial supply of “seed” (larvae, juveniles) exists for any of the four species groups. The use of wild-caught seed for their capture-based aquaculture potentially affects their capture fisheries but any damage caused has neither been fully defined or understood nor quantified.
? Eels: eel culture benefits from well-developed artificial feed supplies, has low environmental impacts, and requires limited land. The main constraint to the expansion of this sector is seed supply, which can only be solved by hatchery production.
? Groupers: the further expansion of grouper rearing will depend primarily on market development. However, better seed catching and culture techniques to reduce wastage, the development of commercially acceptable artificial feeds to replace “trash fish”, better control of diseases, and a transfer of culture activities away from polluted areas are also necessary.
? Tunas: further expansion of tuna fattening is anticipated in the short-term. However, long-term sustainability depends on increasing the supply of seed, currently constrained by tuna quotas and the lack of economically sound methods of hatchery production; improvements in artificial feed formulation to reduce baitfish consumption, improve FCRs and ensure meat quality; expanding markets beyond the Japanese market; and improvements in offshore technology and harvesting systems. Environmental and ethical concerns affect the public image of tuna rearing but control over the complete life cycle would remove ecological concerns and help to ensure a sustainable future.
? Yellowtails: hatchery-reared yellowtail juveniles are of poorer quality than those that are wild caught, so seed supply remains a constraint. Considerable interest in expanding this form of aquaculture not only exists in Japan, where the traditionally cultured Japanese amberjack is being joined by the rearing of two other species (yellowtail amberjack and greater amberjack), but also elsewhere, notably in Australia and the Mediterranean. Besides solving the problem of seed supply, improved feeds and feeding practices and the introduction of better management to limit losses from “red tide” events are needed. Expanding the range of products available would also be advantageous.
? Environmental impact: there is a strong need for better data on the biology and fisheries of the species included in this report, with a view to determining Maximum Sustainable Yield (MSY) and ensuring sustainability. Seed capture for aquaculture has a potentially negative (but, as yet unquantified) impact that adds to existing high levels of fishing effort, increasing vulnerability to extinction. In addition, other topics causing environmental impact require further study. These include improved site selection; the development of feeds that cause less pollution and are less reliant on limited sources of marine protein and oil; the amelioration of the habitat destruction that is caused by certain types of seed capture; improvements in feeding practices; and better monitoring and control of existing farms.
? Social and economic impacts: capture-based aquaculture provides significant positive returns in areas with depressed and marginal economies, and an alternative livelihood for coastal communities. However, the difficulties of marketing fresh fish and supplying markets that demand live fish (e.g. groupers), and the need to expand markets limit its potential. The development of new, value-added products would alleviate this problem. Increased competition caused by production expansion (e.g. of yellowtail culture) may lead to falling prices, as has occurred with other farmed species. Unique selling positions (USP) need to be identified for the products from capture-based aquaculture. Skill gaps are evident in the sector, including specific knowledge on economics and management, the suitability of individual (new) species for culture, information on their biology and dietary requirements, and marketing. Capture-based aquaculture is labour intensive in its farming and processing operations, and can contribute to poverty alleviation in developing countries.
? Management of resources and culture practices: many difficulties are posed by the interactions between capture-based aquaculture and fisheries. Specific rules that complement existing regulations to improve management practices are required. Innovative technologies and concepts are needed to solve the problems of overfishing, bycatch, and environmental impact (e.g. on seed catching areas for groupers). Considerable efforts are being made to identify adequate responses to the challenges created by capture-based aquaculture, in particular by the General Fisheries Commission for the Mediterranean (GFCM) and the International Commission for the Conservation of Atlantic Tunas (ICCAT) in the Mediterranean. Capture-based aquaculture not only needs recognition as a distinct sector but integration into resource use and development planning. The principles set out in the FAO Code of Conduct for Responsible Fisheries (CCRF) would provide useful guidance towards identifying factors that inhibit sound management and development; consultation with all stakeholders, including the private sector, is essential in this process.
? Food safety issues: in common with other types of aquaculture, careful choice of aquafeed ingredients and on-growing sites, in addition to good management practices, are necessary to avoid the accumulation of chemical and antibiotic residues, in order to ensure the continued safety of farmed products. Capture-based aquaculture provides other opportunities to reduce the risks associated with food safety. For example, where ciguatera is a problem, capture-based products might be labelled as “ciguatera-free”. Certification systems would be advantageous for capture based aquaculture products.
? Statistical issues: specific statistical problems exist where the animals stocked for on-growing are already of significant size. Of the four species groups considered in this report, this problem applies only to bluefin tuna fattening; however it also applies to other species where large wild-caught seed are (or may in the future be) stocked in capture-based aquaculture. The difficulty of separating the early (fisheries) production from late (aquaculture) production of tunas is a topic of intense discussion within GFCM and ICCAT. Practical difficulties (e.g. multiple handling of live fish to measure weight) exacerbate the statistical problems.
? The future: capture-based aquaculture is an economic activity that is likely to continue to expand in the short term, both for those finfish species currently under exploitation and possibly with others that may be selected for aquaculture in the future. However, in the long term, the capture based aquaculture of certain species of finfish may have to cease, through legislation, if it is viewed as a threat to their fisheries, to natural recruitment in the wild, and perhaps to their very existence. This is why it is critically important that means be found to rear these species throughout their full life-cycle that are economically viable. When that goal is achieved, not only will the future aquaculture production of those species be assured but restocking programmes may be feasible to enhance their capture fisheries. While there are opportunities for market expansion for all of the species discussed in this report, there is a proven tendency (e.g. salmon, seabass, seabream) for farm-gate prices to decline as supply increases. Thus expansion will only be feasible if farmers are able to reduce costs. From a technical point of view the main constraint to expansion is seed supply.
? In conclusion: the development of seed production in hatcheries on an economically viable commercial scale, and the refinement of grow-out technology to ensure that the fattening phase is environmentally acceptable are the critical issues for the future. Failure to address these matters successfully would have severe consequences for both aquaculture and capture fisheries.