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A Strategic Framework for Scottish Aquaculture

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A Strategic Framework for Scottish Aquaculture

Appendix 4: Research priorities

(extracted from The Review and Synthesis of the Environmental Impacts of Aquaculture)http://www.scotland.gov.uk/cru/kd01/green/reia-00.asp

1. The following list of research priorities is not itself in priority order; nor is it exhaustive. As the aquaculture industry develops new species, husbandry practices and technologies, some of the research needs listed may acquire a different priority and new research priorities will emerge. It is intended, therefore, that this list be kept under continuous review, along with Appendix 3, as new findings become available.

2. Although the gross effects of fish farming on sediments are relatively well understood, much remains to be done regarding the dynamics of waste input, responses from the sediments in terms of the interactions between microbial and macro-biological processes, how these influence the chemistry of the sediments, and the physical processes of oxygen supply, sediment resuspension and mixing by water currents. These interactions take place against a background of seasonal changes and the 2-year farming cycle that results in great variation in the supply of organic materials to sediments. In addition, inter-annual variability in biological factors such as the supply of invertebrate larvae probably has effects that are not as yet well understood. These aspects are important as they affect: a) our understanding of the assimilative capacity of sediments with respect to farm wastes; b) the ways in which chemical contaminants in sediments are redistributed to the wider environment and; c) the ways sediments consume oxygen and release dissolved nutrients into the water column. Such studies will inform the determination of benthic carrying capacity.

3. Further studies should be undertaken of phytoplankton abundance and species composition in some lochs originally studied before 1984 and now the sites of major fish-farms.

4. A few key coastal sites should be chosen to bring together long-term programmes of monitoring of nutrients, phytoplankton and algal toxins. The historic and future data collected in this way should be subject to statistical analysis and compared with predictions from mathematical models. The sites should represent a range of loadings by fish farms.

5. Inflows of nutrients from the Atlantic Ocean and the Irish Sea should be monitored in Winter and in Summer; such inputs are likely to change because of climate change as well as changes in nutrient enrichment of the Irish Sea.

6. Better understanding is needed of water movements within sea-lochs and voes, between them and coastal waters, and in coastal waters.

7. Studies are required of the biology, toxicology and ecology of Scottish populations of harmful algae, especially of Pseudo-nitzschia species.

8. Methods capable of detecting the presence of toxins in small samples of phytoplankton need to be developed: present methodology relies on analysis of shellfish tissues, and can thus provide only indirect information about toxic algae.

9. A better understanding is needed of the role of pelagic protozoa in coastal waters, lochs and voes; these organisms may be crucial in preventing the development of algal blooms, yet especially sensitive to pollution with metals or pesticides.

10. More information is required on rates of loss of nutrients from Scottish continental shelf and sea-loch waters, especially concerning the process of denitrification which takes place in organically enriched sediments.

11. Development of simple but robust models to predict undesirable disturbance to the balance of organisms and the quality of the water as a result of inputs of nutrient and organic matter by fish farms must continue. With priorities 2-9 above, this will inform understanding of the carrying capacity of the Scottish coast for aquaculture and other users.

12. Further study is required of the interaction of suspended-culture mussel populations with other components of the ecosystem, in terms of their scope for growth (phytoplankton availability), their impact on other suspension feeders in the food web and the potential for nutrient release from accumulated biodeposits. Such studies should be linked to the development of models to assist in the calculation of appropriate stocking densities for each bivalve cultivation area and the identification of sites where mussel cultivation could be practised to advantage.

13. Fuller study of the potential benefits of integrating aquaculture species is required, using a combination of nutrient extracting species on site with nutrient enriching species, with a view to increased productivity in the former and a net reduction in nutrient release from the latter, thus influencing carrying capacity.

14. There is a need to improve our understanding of the mechanism of toxification and depuration of ASP in commercially valuable species such as the king scallop. There is little information at present on the levels and mechanisms of production of domoic acid in Pseudo-nitzschia species isolated locally, the reason for prolonged toxin retention in king scallops or the potential impact of the ASP on shellfish physiology, fecundity and recruitment.

15. More information is required on the toxicity of emamectin benzoate, teflubenzuron, copper and zinc to benthic organisms commonly found in Scottish sea lochs.

16. More information is required on the long-term effects of cypermethrin, emamectin benzoate, copper and zinc on sediment-associated organisms. In particular:

  • what proportion of the chemicals, particularly the metals, present in fish farm sediments is bioavailable?

  • is there potential for these chemicals, particularly the metals, to accumulate up the food chain?

  • what happens when a site is fallowed and the sediment biogeochemistry changes? Do the chemicals that have accumulated, and are possibly not biologically available in the organically enriched sediment, become bioavailable as chemical remediation occurs? Are they released, and do they disperse over a wider area? Do they prevent recolonisation of impacted sites?

17. More information is required on the dispersion, fate and potential long-term effects of multiple cypermethrin treatments (at single and multiple farm sites) within a loch system.

18. More information is required on the potential effects of concurrent emamectin treatments at several farm sites within a loch system.

19. Antifoulant usage by the aquaculture industry should be quantified. Copper and zinc concentrations, speciation and toxicity in fish farm sediments need to be investigated.

20. Research is required to quantify the factors responsible for the transmission of lice between farms and wild fish. Improvements in understanding the mode and rate of transmission are essential in providing information on the relationships between infection of wild populations, lice burden on farms and separation distances between migratory fish routes and fish farms. This would also enhance understanding of the mechanisms by which farmed fish are infected with sea lice from wild populations and from other farms, would assist in determining the reasons why some sites have fewer lice problems than others and would therefore also assist in the selection of better sites for salmon culture.

21. Continued surveillance of the presence of escaped fish in wild populations and quantification of the effects in terms of population fitness are required.

22. Improvements need to be made in marking or tagging fish to enable easy identification of escapees.

23. New methods for reducing the fertility of farmed fish are needed.

24. Improved containment technologies, including technologies for reducing the costs of operation of fully contained systems, should be developed.

25. Studies of the causes and ecological consequences of the decline of wild salmonids are required.

26. The effects of acoustic seal scarers on cetaceans should be assessed.

27. Accurate fisheries data collection and mathematical modelling of the pelagic fisheries are required in the main industrial fishing areas to ensure the sustainability of these fisheries. The influence of climate oscillations ( e.g. El Niño) and climate change on recruitment and spawning stock compared with the impact of industrial fisheries are also very difficult to quantify and little research has been published in this area. The sustainability of the blue whiting fishery in the North Atlantic fishery also requires urgent research.

28. The effects of near market use of plant meal and oil substitutes on fat and protein composition, flesh quality and taste in salmonids should be studied.

29. Studies are required on refining the vegetable oil and protein requirements of the cultured fish species relating to life stage and seasonal variations in digestibility experienced with certain vegetable oils.

30. Better information is required regarding blending oils, reducing the dependency of manufacturers on a few plant oils and tailoring the taste of the final product to the customer needs.

31. Information is needed about nutritional studies and the implications of substituting fishmeal and oils with vegetable alternatives for new species for cultivation, particularly cold-water species such as cod, haddock, turbot, halibut, Dover sole and lemon sole.

32. Research is required into the environmental impacts of new aquaculture species, including work on wastes, diseases, parasites and escapes.