Marine Mammal Bycatch: Incidental Capture in Fishing Gear

Bycatch of marine mammals in fishing gear kills or injures hundreds of thousands of animals annually. Reducing this incidental capture is one of the most urgent and tractable marine welfare challenges.

Key Facts

The FAO estimates that 300,000 cetaceans (whales, dolphins, porpoises) die in fishing gear entanglement annually
Gillnets, longlines, trawl nets, and trap gear all pose entanglement and drowning risks to marine mammals
Cetaceans are air-breathing — entanglement in underwater gear causes drowning within minutes to hours
The vaquita (Gulf of California porpoise) is critically endangered with fewer than 10 individuals remaining due to gillnet bycatch
Pinniped (seal and sea lion) bycatch causes direct mortality and entanglement injuries in commercial fishing operations
Acoustic deterrents (pingers) on nets significantly reduce cetacean bycatch in many fisheries
On-board observer programmes and electronic monitoring improve bycatch detection and accountability

Welfare Considerations

Bycatch death by drowning is an acutely traumatic and welfare-significant event for air-breathing marine mammals. For species like porpoises and dolphins with complex social structures, bycatch mortality also has population-level social welfare implications through disrupted bonds and group composition. Entanglement that does not result in immediate death causes prolonged suffering through wound infection, impaired swimming and feeding, and exhaustion. Reducing bycatch requires a combination of gear modification, fishing practice changes, and strong observer and monitoring systems.

What You Can Do

Choose seafood certified under schemes that assess and minimise marine mammal bycatch
Support organisations advocating for gillnet bans in critical cetacean habitats
Ask seafood retailers and restaurants about their bycatch reduction policies
Support campaigns to protect the vaquita and other critically endangered species from bycatch
Advocate for mandatory electronic monitoring on fishing vessels to improve bycatch accountability
Learn about the bycatch footprint of different seafood species and fishing methods before purchasing