Marine Mammal Bycatch: Reducing Incidental Deaths in Fishing Operations

Dolphins, porpoises, whales, and seals die as bycatch in fishing operations worldwide. Reducing this mortality requires technical innovation and strong fisheries management.

Key Facts

Estimated 300,000 cetaceans (whales, dolphins, porpoises) die annually as bycatch in commercial fishing operations
Gillnets are the most lethal fishing gear for small cetaceans — animals become entangled and drown
The vaquita porpoise is critically endangered with fewer than 10 individuals remaining, driven primarily by bycatch in gillnet fisheries
Acoustic deterrents (pingers) on gillnets significantly reduce harbour porpoise and common dolphin bycatch
Circle hooks and fishing light technology reduce sea turtle bycatch in longline fisheries
Bycatch welfare assessment must consider drowning as a form of death that can involve suffering over extended periods

Welfare Considerations

Marine mammal bycatch is a large-scale welfare problem with clear technological and policy solutions, yet implementation remains incomplete. Animals that drown in fishing gear experience a distressing death — struggling against entanglement before losing consciousness from oxygen deprivation. The suffering involved warrants treatment as a serious welfare harm, not merely a conservation problem. For highly intelligent animals like dolphins and porpoises with complex social lives, bycatch mortality also disrupts social groups with cascading welfare effects. Mitigation technology exists: pingers, escape hatches, modified gear designs, and area closures have all demonstrated effectiveness in reducing bycatch without commensurate loss of target species catch. The welfare case for strong bycatch reduction regulations complements the conservation case, and both should inform fisheries management decisions.

What You Can Do

Choose seafood certified by schemes that include bycatch reduction requirements (MSC, Friend of the Sea)
Avoid seafood caught by methods with high bycatch rates — check consumer guides from Monterey Bay Aquarium Seafood Watch
Support organizations advocating for stronger bycatch reduction regulations in international fisheries bodies
Advocate for mandatory pinger use on gillnets in waters with significant porpoise and dolphin populations
Learn about the vaquita and other critically endangered species driven to the brink by bycatch