Predation of South American sea lions (Otaria flavescens) on artisanal fisheries in the Rio de la Plata estuary

Interactions between pinnipeds and fisheries occur whenever there is spatial overlap between them. In Uruguay, the South American sea lion (Otaria flavescens) interacts frequently with artisanal fisheries by preying upon entangled fish. The objective of this study was to evaluate sea lion interactions with gillnets in three fishing ports of the Rio de la Plata estuary during an entire year. Data was collected on-board during 82 routine trips with artisanal fishermen. Minimum and maximum predation scenarios were estimated per fishing event. The number of pinnipeds interacting with artisanal fisheries was significantly higher in winter and spring, coinciding with the reproductive cycle of these animals. Catch per unit of effort did not differ significantly with presence or absence of interactions. Damage in all fishing ports was low, but significantly higher in autumn and spring, representing between 1.4 and 15.9% of potential catches, considering minimum and maximum scenarios. In addition to season, two factors may be influencing the magnitude of the interactions: distance to the closest colony and magnitude of fisheries landings. According to this study, sea lions did not cause a significant loss to artisanal gillnets. Further studies should consider this conflict as a component of socio-ecological systems using participative research to facilitate co-management. (C) 2013 Elsevier B.V. All rights reserved.