Scottish Animal Welfare Commission - proximity of seals to farmed fish: response to Marine Scotland

Conclusions and recommendation

While there are no published data available, it is the opinion of veterinarians and farm managers that seal presence causes significant stress in farmed salmon and this contributes to reductions in growth, feeding and increased incidence of disease. In addition, seal attacks cause significant injury and mortality.

Evidence from other species also suggests that chronic stress occurs in prey animals when exposed to the constant or frequent presence of a predator.

Chronic stress in other species, including that caused by high predation risk, causes changes in feeding, growth, immune responses and disease susceptibility

Recommendation

Although there is little direct published evidence, it appears to the SAWC Aquaculture working group that on the balance of probability, even in the absence of direct losses due to predation, in many situations the continued close proximity of predatory seals to farmed salmon is likely to cause significant and prolonged changes in fish behaviour, growth and health as a result of acute and chronic stress. This is likely to result in poor overall welfare, and poor feeding and loss of resilience to disease with consequent economic losses.

SAWC recommends that issues related to the impact of seals on the welfare of farmed salmon should be regarded as a legitimate factor when MS-LOT are considering the licensable purpose test for applications for the use of ADDs in these situations, noting the other tests and possible mitigations regarding the specification and use of ADDs that also need to be considered.

However, it is clear that several studies have demonstrated negative impacts on the behaviour of cetaceans and seals, so that inappropriate use of ADDs could compromise their welfare and legal protections, including as European Protected Species. Thus, there is a clear welfare conflict between the effects of ADDs on wild marine mammals and the impacts of close proximity and direct predation of seals on farmed salmon.

SAWC strongly supports the principle that government policy decisions should have due regard to the welfare of sentient animals. Therefore, when considering the use of ADDs, there is clearly a need to balance the welfare interests of seals and cetaceans with the need to protect the welfare of farmed fish. Where possible, salmon farmers should strongly consider all possible alternatives to ADDS and to use a deployment schedule and specification of ADD that is likely to cause the least impact on non-target species. SAWC intend to provide a further opinion on this in due course.