Wild Dolphin Bycatch: Gillnet Mortality and Mitigation Technologies

Thousands of dolphins and porpoises are killed annually as bycatch in gillnet fisheries. Acoustic deterrent devices and modified fishing methods can dramatically reduce cetacean bycatch with minimal impact on target fish catches.

Key Facts

An estimated 100,000+ small cetaceans (dolphins and porpoises) are killed annually as bycatch globally
The vaquita porpoise, with fewer than 20 individuals remaining, faces extinction from totoaba gillnet bycatch in the Gulf of California
Harbor porpoises are particularly vulnerable to static gillnets because their echolocation does not detect fine monofilament
Acoustic pingers attached to nets warn porpoises of net presence and have been shown to reduce bycatch by 50-90%
Pinger requirements have been mandated in EU fisheries targeting sprat and herring in porpoise-sensitive areas
Fish aggregating devices and modified net types can shift fisheries away from dolphin-associated schools
Drift gillnets were banned in US West Coast waters due to unacceptably high marine mammal bycatch
The Drive Project and other research groups are developing improved pinger technologies and protocols

Welfare Considerations

Cetacean bycatch welfare harm involves drowning - animals whose respiratory physiology requires surfacing cannot survive entanglement in submerged nets. Individual dolphins and porpoises drown in gear, experiencing acute asphyxiation. The vaquita situation represents the extreme end of bycatch welfare - a species reduced to the verge of extinction by incidental fishing mortality. The welfare solution is technologically available: acoustic pingers have been demonstrated to reduce harbor porpoise bycatch by over 80% in controlled studies. Regulatory implementation remains incomplete. Consumer choices for certified sustainable seafood from pinger-using fisheries create market incentives for adoption, while regulatory advocacy remains the most powerful lever for change.

What You Can Do

Choose seafood from fisheries certified to use bycatch reduction technologies including pingers
Support organizations working on vaquita emergency conservation measures
Advocate for regulatory requirements for pingers and other bycatch reduction devices in gillnet fisheries
Donate to research developing next-generation bycatch reduction technologies
Reduce consumption of species like shark and swordfish caught in particularly high bycatch fisheries