Abstract

In this review, we summarize and discuss the main interactions affecting salmon farming and pinniped populations worldwide. Out of seven pinnipeds commonly engaged in these interactions, only one, Eumetopias jubatus, is currently listed, as 'Near Threatened', by the IUCN. This scenario may change as the salmon farming industry is expanding to higher latitudes and climate change is threatening many pinniped populations. Pinniped attacks cause productive and economic losses, equivalent to 1%-12% of gross production costs, due to predation, induced escapes and implementing deterrent measures. Other potential negative effects on the industry remain unassessed: lower fish growth, immunosuppression, diseases transmission, damaging infrastructure and injuring farmworkers. Main direct threats to pinnipeds include intended and unintended killing, which lack independent quantifications and have generated a growing number of ethical, economic and socio-political concerns, as well as trade regulations affecting the industry. Physical perturbation, pollution, nutrification and/or prey subsidies related to this industry may induce behavioural, trophic and social changes, as well as breeding and/or foraging habitat loss/change in impacted areas. Despite their relevance, the magnitude and consequences of these potential impacts have been poorly evaluated and documented, precluding us from assembling accurate assessments on most interactions. Hence, we recommend focusing further research on assessing the effects of these interactions and make a call for implementing and maintaining reliable and independent records of: (i) intended and unintended killings and (ii) demography of affected populations. Implementing an ecosystem approach may be key to reduce negative impacts of salmon farming on pinnipeds and coastal ecosystems.