Report of the Working Group on Environmental Interactions of Mariculture

WGEIM met at the University of Rhode Island from 24–28, April 2006. The meeting was attended by 11 members and one observer from six countries. Six terms of reference were addressed by the group and are summarised below.

The WG continued to develop a series of documents concerning risk analysis of the consequences of genetic interaction between farmed fish and conspecific wild stocks, as part of a joint project with GESAMP WG31. The documents consist of an introductory paper describing the risk analysis approach, and case studies of five non-salmonid aquaculture species (cod, halibut, sea bass, sea bream and turbot). The WG agreed that the papers were nearing the standard and completeness necessary for submission for peer reviewed publication. The WG recommended that the documents be completed intersessionally and submitted to an appropriate journal.

The WG continued to review existing (EU) legislation or proposed legislation and assess the impacts of the legislation on mariculture activities. Under the Water Framework Directive, no obvious mariculture impacts were highlighted based upon the implementation activities within the intersessional period. Proposed legislation is the European Marine Strategy (EMS), the Strategy for Sustainable Development of European Aquaculture and amendments to the EU Data Collection Regulation all of which might have some impacts on aquaculture activites. The group continued to investigate the applicability of sustainability indicators for aquaculture. SI’s are different from “impact” indicators in that they are more comprehensive, including considerations of not only environmental but also social and economic sustainability. Sustainability indices (SIs) are needed by aquaculture resource managers who must sort through large amounts of scientific information and make numerous environmental decisions. SIs offer a means to prioritize those aquaculture systems most in need of immediate management attention and allow scarce management assets to be applied in the most costeffective manner. SIs are also valuable for owners of seafood businesses who wish to procure “sustainable seafoods” for this rapidly growing consumer movement. The group considered and evaluated the current status and suitability of SIs for mariculture and selected a suite of SIs that are simple, flexible and cost effective. The group used a matrix approach that maps “sustainability trajectories” and was applied to salmon farming in New Brunswick, Canada and Norway. A number of recommendations were forthcoming from this term of reference. WGEIM will continue to refine the sustainability trajectories approach using the traffic light system of the UK and Canada and apply this example to salmon and shellfish aquaculture farming systems.

Integrated Multi-Trophic Aquaculture (IMTA) represents a global aquaculture sector of growing interest and potential development in the world. Although much of this interest has been expressed through ongoing research initiatives, there has been some movement towards commercialization through large-scale testing of these opportunities. The evolution from monoculture aquatic food production systems to integrated, multi-species systems is envisioned as a shift towards a sustainable approach, and one that has seen parallel developments occur in the terrestrial food production industries.

Results of research programs in North America and Europe would suggest that IMTA has high commercial potential, but that there are still some challenges remaining in terms of R&D, regulatory framework development, and product acceptability. Experimental and pilot-scale systems are providing growing evidence that there are low-level risks associated with contaminant transfers among Integrated Aquaculture components, and that these periodic risks are manageable in terms of husbandry practices and with appropriate regional/international regulatory requirements for seafood inspection. The legal frameworks that currently apply to the aquaculture industry, in most jurisdictions, are considered sufficiently flexible as to accommodate the development of Integrated Aquaculture systems and it is clear that the environmental, economic and social benefits associated with this sustainable approach to aquatic food production outweigh the risks.

The potential advantages and disadvantages of integrated mariculture, based on our assessment of the environmental, social and economic considerations for this sector were presented. In addition, number of information gaps were highlighted and research and development initiatives were recommended.

One of the obvious short-comings of research to date is that studies on substitution of fish meal and fish oil have been mutually exclusive. Many of the promising results from substitution of fish oils with plant oils have been due, in part, to inclusion of high levels of fish meal in the same diet. The fish meal provides some of the essential fatty acids that would have normally been provided directly by the fish oil. Although other novel sources of essential fatty acids are available, they must become more economical before they can sustain the needs of the aquaculture industry. Nevertheless, great advances in reducing, if not eliminating, the reliance upon wild fisheries resources for aquaculture feed ingredients are being made.

The primary conclusion is that during the intersession WGEIM will carry out a review and evaluation of recent advances on alternative sources of lipid and protein to fish oil and fish meal in aquafeed. It is proposed that WGEIM review a draft manuscript at the 2007 meeting that is to be submitted for publication in a peer reviewed scientific journal.

To date, the interaction of mariculture with exotic species and more specifically unintentional species introductions has received limited attention. This is despite the fact that exotic species are having significant impacts on the aquaculture industry worldwide and more particularly for the shellfish aquaculture industry.

The importance of bivalve culture in the promotion and transfer of exotic aquatic species as well as the importance of these exotic species to bivalve culture and the environment. Specifically, we focused on exotic species with an emphasis on those that become invasive and nuisance. Management implications and mitigation strategies are also addressed. It should be noted that the majority of the existing literature addresses the issues as they relate to oyster culture, probably because this appears to be the single greatest vector for all types of introductions (planned or otherwise) in bivalve aquaculture. There is little published information about other bivalve species with respect to their role as vectors for exotic species.