Operational interactions between South American sea lions and gillnet fishing in southern Brazil

Abstract

Abstract This study describes operational interactions between coastal gillnet fishing and South American sea lions (Otaria flavescens) off the southern Brazilian coast. In total, 263 onboard surveys were carried out during three periods between 1992 and 2012 in fishing boats from two harbours on the northern coast of Rio Grande do Sul State: Passo de Torres (29°19'S; 49°43'W) and Imbé (29°58'S; 50°07'W). Interactions of South American sea lions were observed in 116 (24.0%) out of 484 fishing operations. These interactions were more frequent in fishing boats from Passo de Torres (frequency of occurrence FO = 42.8%) than those from Imbé (FO = 14.8%; P < 0.001) and during autumn and winter months. Interactions between South American sea lions and fishing activities with fixed bottom gillnets in Imbé were most frequent during period III of the study (2011/2012) (FO = 52.0%; P = 0.032). These results demonstrated that interactions are not as high as reported/complained about by the local fishermen who tend to exaggerate the impact of these interactions. It is suggested that reduced fish stock and increased fishing effort during recent decades is raising the frequency of encounters with South American sea lions during fishing activities off the southern Brazilian coast. Therefore, the implementation of fishery management measures that reduce fishing effort and that integrate environmental education programmes are essential to reduce conflicts between fishing activities and the sea lions in the region. Copyright © 2015 John Wiley & Sons, Ltd.