Harbor Porpoise Bycatch Welfare and Mitigation

Harbor porpoises are among the most frequently bycaught small cetaceans globally, and improving mitigation methods requires understanding of their welfare during incidental capture.

Key Facts

Harbor porpoises are the most common cetacean in the North Sea and Northeast Atlantic
Bycatch in set gill nets and trawls kills tens of thousands of harbor porpoises annually in European waters
Porpoises caught in gill nets often show evidence of struggling and drowning, indicating significant suffering
Acoustic deterrent devices called pingers can reduce porpoise bycatch by 30-90% when used correctly
Pinger effectiveness degrades over time as porpoises may habituate to the signals
Post-mortem studies reveal internal hemorrhage and lung damage consistent with a traumatic death in bycaught individuals

Welfare Considerations

The welfare dimension of porpoise bycatch is severe: drowning in a net involves acute hypoxia, panic, and physical injury from struggling. Post-mortem evidence consistently shows traumatic cause of death. While pinger technology has reduced bycatch significantly in some fisheries, compliance and maintenance issues limit their effectiveness. Emerging technologies including onboard observer requirements, electronic monitoring systems, and modified net designs show promise. The welfare case for rapid scaling of bycatch reduction measures is compelling, as each bycatch event involves preventable acute suffering.

What You Can Do

Support organizations like the Whale and Dolphin Conservation Society working on bycatch reduction
Choose seafood certified by schemes that include bycatch reduction requirements
Advocate for mandatory use and maintenance standards for acoustic deterrent devices in gill net fisheries
Support funding for research into next-generation bycatch reduction technology