Sea lion and fur seal interactions with fisheries and aquaculture in South American waters: threats and management perspectives

Abstract

The main issue affecting the conservation of most pinniped species has been identified as interactions with fisheries and aquaculture. In South American waters in particular, this problem has not been well evaluated. Consequently, there is an urgent need for research and conservation measures to address the problem, particularly for species of conservation concern. In this study, we reviewed published and unpublished research and observations from the last 25 years on operational and biological interactions between pinnipeds and fisheries and salmonid aquaculture activities in South American waters, and the conservation and management implications of these interactions in the near future. Two species of pinnipeds are primarily involved in biological and operational interactions with fisheries and aquaculture in South America: the South American sea lion Otaria flavescens and the South American fur seal Arctocephalus australis. Although phocids are present in South American waters, there is no published research on conflicts between phocids and human activities. Interactions between fisheries and pinnipeds have been reported by many countries. In South American waters, interactions mostly involve male and subadult male South American sea lions. However, despite the high frequency of interactions, the estimated economic losses to fisheries and aquaculture related to sea lion depredation are generally low. Incidental capture and mortality of pinnipeds has been reported, especially in artisanal gillnet fisheries and in industrial purse seine and trawl fisheries. Mortality of sea lions in salmonid aquaculture has been reported, but the magnitude of the problem is unknown. In South America, limited progress has been made to incorporate mitigation measures, such as time-area closures, acoustic deterrent devices, and modifications to fishing gear, into fisheries and aquaculture. This is likely to be due to our limited understanding of ecosystem complexity, the costs of modifying fishing gear or incorporating acoustic deterrent devices, and the scarcity of fishing controls. We suggest that strategies for effectively reducing conflicts between pinnipeds, fisheries, and aquaculture should involve all stakeholders in participative research to facilitate co-management.