Cetaceans including harbour porpoises, dolphins and small whales are caught as bycatch in UK fishing operations, causing drowning deaths and injuries that require monitoring and mitigation.
Cetacean bycatch welfare impacts are severe - drowning in fishing gear causes suffocation that takes minutes and involves extreme distress. Porpoises and dolphins struggling in nets experience panic, exhaustion and eventual death from hypoxia. The welfare scale is significant: estimated porpoise bycatch in the North Sea alone runs to thousands of individuals annually. Monitoring improvements are needed to understand true bycatch rates - current estimates are based on limited observer data and stranding analysis. Mitigation through pinger use and gear modification reduces bycatch but requires enforcement. The welfare case for observer programme expansion and mandatory pinger use in high-risk fisheries is strong.