Toward a Global Estimate of Cetacean Bycatch: Data Gaps and Future Needs

Abstract

Cetacean bycatch remains a major global conservation concern, yet consistent estimates are limited by widespread data gaps and inconsistent monitoring. This study integrates published bycatch estimates with satellite-derived fishing effort data from Global Fishing Watch to assess global patterns of risk across gear types and regions. Through a systematic review of 48 studies and analysis of over 13.9 million vessel days of fishing activity in 2023, the research identifies gillnets as the highest-risk gear and highlights South America as a region of particular concern due to intensive gillnet and trawl fisheries with minimal monitoring. Although bycatch persists even in heavily regulated areas, regions with high fishing pressure and little oversight present the greatest unrecorded threats. The findings emphasize the urgent need for expanded monitoring, standardized reporting, and collaborative, fisher-led mitigation strategies to reduce cetacean bycatch and support sustainable fisheries management worldwide.