Vivendo entre desafios: sobreposição espaço-temporal de Pontoporia blainvillei e Sotalia guianensis com atividade pesqueira no sul de Ilhabela, São Paulo, Brasil

Abstract

Bycatch in fisheries is considered one of the primary threats to cetacean conservation globally. This study aimed to assess the risk of spatial and temporal overlap between Pontoporia blainvillei and Sotalia guianensis and fishing activities in southern Ilhabela, São Paulo, Brazil. The data used were obtained through systematic monitoring conducted by the VIVA Instituto Verde Azul from a fixed land-based observation point between 2020 and 2024. The Bycatch Risk Assessment (ByRA) model was used to map critical areas of interaction between cetaceans with fishing activities and to estimate indices of exposure, consequence, and risk during cold and warm seasons, based on sea surface temperature. Risk patterns varied according to fishing gear type and season, with high concentrations observed in coastal regions for both species. Bottom trawling showed higher mean values for exposure, consequence, and risk, whereas gillnets showed higher proportions of high-risk grid cells, representing spatial risk hotspots. The high rates associated with trawling highlight a significant knowledge gap regarding the potential impacts this fishing method may have on cetaceans. The critical areas (hotspots) spatially identified in this study are important sites for cetacean occurrence and highlight the need for continuous monitoring and the development of effective socio-environmental conservation strategies.