Abstract

Growing global concern about the impacts of non-selective fisheries on marine mammals has resulted in an increase in international agreements and national regulations that pressure national governments, such as Chile, to develop scientifically based, cost-effective methods for assessment, monitoring, and reduction of bycatch. This study presents an expert elicitation approach to characterize bycatch mortality of marine mammals in small-scale fisheries in Chile, with particular focus on the Chilean dolphin (Cephalorhynchus eutropia). Given its restricted distribution and vulnerability to multiple anthropogenic threats, the Chilean dolphin represents a key candidate for piloting a comprehensive and scalable bycatch monitoring program. The methodology establishes baseline data on bycatch mortality by integrating an expert elicitation approach using the IDEA method to improve accuracy and reduce uncertainty, alongside regional stakeholder workshops and interview surveys with small-scale fishers. Results indicate that bycatch mortality occurs throughout the species' range with an average estimated value of 17 dolphins killed each year. Inshore gillnets were identified as the primary gear responsible for bycatch mortality. Fishers' perceptions of Chilean dolphin conservation were generally positive, suggesting openness to mitigation measures. Regular implementation of this cost-effective structured elicitation approach can support adaptive management and contribute to more effective fisheries regulations. It also represents a scalable approach that fisheries agencies can use as a starting point for improving bycatch monitoring efforts in other locations where small-scale fisheries are causing marine mammal bycatch.