Abstract

In this review, we summarize and discuss the main interactions affecting salmon farming and pinniped populations around the globe. Pinniped attacks from seven different species cause productive and economic losses in all major salmon production areas, including predation, induced escapes, lower growth rates, immunodepression and enhanced production costs related to control and deterrent measures. Main direct threats to pinnipeds include entanglement in anti-predator nets and intended killing near salmon farms. Indirect threats include behavioural changes and loss or modification of breeding and foraging habitats due to physical perturbation, chemical pollution, nutrification, and trophic subsidy effects. Although these treats may seriously impact the dynamics, social structure, and conservation status of local population units, such effects have been poorly monitored and documented. Therefore, although only one of these seven species is listed in a category of concern (near threatened) by the IUCN, intended and unintended pinniped killings have been rising a growing number of ethical, economic, and socio-political issues. We found major data and knowledge gaps limit an objective discussion and assessment of most of these issues. Therefore, we recommend that reliable independent mortality records become implemented and maintained, and that affected populations begin to be monitored regularly, both in the short term. In the medium term, we believe a broader ecosystem approach is needed to reduce the negative impacts of salmon farming on coastal ecosystems.