Wild Dolphin Bycatch Welfare and Mortality

Dolphins caught as bycatch in commercial fisheries experience some of the most acute and preventable welfare harms in the marine environment, including drowning, physical injury, and stress-induced mortality.

Key Facts

Approximately 300,000 cetaceans including dolphins and porpoises die as fisheries bycatch annually worldwide
Gillnets are the most lethal gear type for dolphins; entangled animals drown within minutes if unable to surface
Purse seine nets used in tropical tuna fisheries are set on dolphin schools to locate yellowfin tuna, catching dolphins in the encirclement
The eastern tropical Pacific tuna fishery killed millions of dolphins through the 1970s-80s before international pressure prompted reforms
Pingers — acoustic deterrent devices — reduce porpoise bycatch in gillnet fisheries by 70-90% when properly deployed
Bycatch dolphins that are released alive often have injuries, stress hormone spikes, and separation from pod members
The vaquita porpoise (fewer than 10 individuals) faces extinction almost entirely from bycatch in illegal gillnets
Observer programmes on fishing vessels are critical for accurate bycatch quantification but coverage is very low globally

Welfare Considerations

Dolphin bycatch causes acute, severe suffering. Entanglement in gillnets leads to drowning — a distressing death involving struggling, oxygen depletion, and sustained fear before loss of consciousness. Dolphins caught in purse seine encirclements experience prolonged stress from crowding, handling, and disorientation before release or death. Even dolphins released alive from bycatch events may have sustained injuries, been separated from their social group, or experienced sub-lethal stress that affects health and reproduction. The welfare case for bycatch reduction is unambiguous and the technical solutions exist: pinger deployment, modified gear designs, observer requirements, and fishing area/season restrictions. The barrier is primarily economic and enforcement-related rather than technical. Consumer pressure and ecolabel certification have driven meaningful reductions in some fisheries and represent a powerful lever.

What You Can Do

Choose tuna certified under dolphin-safe programmes with independent verification (not merely label claims)
Support Monterey Bay Aquarium Seafood Watch recommendations when purchasing seafood
Advocate for mandatory pinger deployment and observer coverage requirements in national fisheries regulations
Donate to organisations campaigning for strengthened international bycatch reduction agreements
Support vaquita emergency response efforts as a critically important bycatch welfare and conservation case