Community Research and Development Information Service - CORDIS

Summary of recommendations

The Final Report for Workpackage 8 includes the background to SUMBAWS, an overview of the project and our recommendations. A socio-economic perspective underpinned much of the experimental science and we focused on economic impact analyses of the aquaculture and game angling industries in Norway, Scotland and Ireland. Cash values and attributable jobs are notoriously difficult to evaluate but it is clear that angling and aquaculture both are significant sources of employment, often in remote rural areas. The experimental evidence and socio-economic modelling both pointed to interventory treatment of wild smolts (to protect them against sea lice infection) as not offering an appropriate management or conservation strategy.

The objective of zero ovigerous lice on farms is attainable, but the costs probably will not be economically and environmentally acceptable as the aquaculture industry is presently structured. Physiological markers of stress of host fish in response to lice infestation allowed us to recommend sublethal threshold lice levels that are indicative of significant stress. These intensities (12 L. salmonis.fish-1 for wild sea trout smolts, and 20 L. salmonis.fish-1 for hatchery salmon smolts) could be utilized as benchmarks by both wild and farmed fish sectors in the interests of fish husbandry and welfare. Intensities <20 L. salmonis.fish-1 probably already is attained for post-smolts placed at sea on most salmon farms. For wild sea trout, we recommend that populations of fish showing <10% of individuals above the 12 L. salmonis.fish-1 threshold should be considered acceptable. For populations exceeding this proportion we would recommend a balanced judgement being taken regarding precautionary intervention if adjacent aquaculture activity is deemed a potential threat to wild salmonids.

Monitoring of wild salmonid stocks is increasingly being compromised by the closure of interventory and in-river fisheries. Whilst this is beneficial from a stock conservation standpoint, it has also to be recognised that unique opportunities of obtaining invaluable scientific data on the health and performance of wild stocks is irretrievably lost. The highest priority should be given to monitoring wild stocks wherever possible.

Reported by

University of St Andrews, Gatty Marine Laboratory
East Sands
KY16 8HL St Andrews, Fife
United Kingdom
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