Harbor Porpoise Bycatch: Welfare in North Sea Fisheries

Harbor porpoises are frequently caught as bycatch in gillnet fisheries, causing drowning deaths and injuries. Understanding the scale and solutions guides effective advocacy.

Key Facts

Harbor porpoises (Phocoena phocoena) are the most common cetacean in the North Sea with an estimated 345,000 individuals
Gillnet bycatch is the most significant anthropogenic mortality source for harbor porpoises in European waters
An estimated 5,000-7,000 porpoises may die as bycatch annually in the North Sea alone
Acoustic deterrent devices (pingers) attached to nets significantly reduce porpoise bycatch when maintained and used correctly
EU regulations require pinger use in specific high-bycatch fisheries but compliance monitoring is inconsistent
Time-Area closures during porpoise calving seasons protect mothers and calves in critical periods
Porpoises that die as bycatch typically drown - unable to surface for air while entangled in nets

Welfare Considerations

Harbor porpoise bycatch drowning is a welfare event of significant severity. Porpoises breathe air and must surface regularly - a porpoise entangled in a gillnet cannot do so, experiencing progressive hypoxia and drowning over minutes. The struggle during entanglement causes further injury. Porpoises that survive net contact with entanglement injuries may subsequently die from infection or inability to feed. The aggregate welfare harm from thousands of bycatch deaths annually is substantial for a species with documented social bonds and cognitive complexity. The availability of effective mitigation measures (pingers, time-area closures) that are not comprehensively deployed represents a policy failure that sustains preventable suffering.

What You Can Do

Choose fish from MSC-certified sustainable fisheries that include bycatch reduction requirements
Advocate for mandatory pinger requirements and compliance monitoring in European gillnet fisheries
Support time-area closures that protect harbor porpoises during critical breeding periods
Donate to organizations monitoring harbor porpoise populations and bycatch mortality
Engage with retailers and supermarkets about their bycatch standards for North Sea fish products
Support research into fishing gear modifications that maintain catch while eliminating porpoise bycatch