Marine Mammal Bycatch: Dolphins, Porpoises, and Whales in Fishing Gear

Marine mammals — including dolphins, porpoises, and small whales — are killed in large numbers as bycatch in commercial and small-scale fisheries globally. Entanglement and drowning cause acute suffering, while population-level impacts threaten species survival.

Key Facts

The International Whaling Commission estimates that over 300,000 cetaceans (whales, dolphins, and porpoises) are killed as bycatch each year — making it the leading direct cause of cetacean death worldwide
The vaquita (Porcupus sinus), the world's most endangered marine mammal, has been driven to the brink of extinction (fewer than 10 individuals) primarily by bycatch in illegal gillnet fisheries in the Gulf of California
Common Dolphins in the Bay of Biscay are a well-documented EU bycatch crisis: thousands are killed annually in French and Spanish trawl and longline fisheries
Entanglement in gillnets — passive mesh nets that trap all animals swimming through them — is the primary bycatch mechanism; animals drown as they cannot surface to breathe
Acoustic deterrents (pingers) have demonstrated effectiveness in reducing porpoise and dolphin bycatch in specific fisheries when properly maintained and deployed
The Marine Stewardship Council (MSC) requires bycatch monitoring and limits as part of its sustainability certification — though enforcement and data quality vary
Some regulatory frameworks (EU Common Fisheries Policy, US Marine Mammal Protection Act) require bycatch monitoring and mitigation, but global coverage is incomplete

Welfare Considerations

Drowning in fishing gear is among the most acutely distressing deaths an air-breathing animal can experience: entangled cetaceans struggle, exhaust themselves attempting to surface, and die of asphyxiation over minutes to hours. Animals that are not fatally entangled but escape may carry embedded gear that causes infection, amputations, and chronic injury. The scale is staggering: 300,000 deaths per year represents a massive, ongoing welfare crisis that dwarfs the attention it receives. Unlike some wildlife welfare issues, solutions are technically available — pingers, modified net designs, time-area closures, and observer requirements can all significantly reduce bycatch — but require political will, funding, and enforcement. Consumer purchasing decisions (avoiding fish from high-bycatch fisheries) remain one of the most accessible individual levers.

What You Can Do

Use the Seafood Watch app or Marine Conservation Society Good Fish Guide to identify fish products from fisheries with low cetacean bycatch rates
Support WDC (Whale and Dolphin Conservation) and ORCA, which campaign specifically for cetacean bycatch reduction
Advocate for mandatory pinger use on gillnets in your country's fisheries and for independent observer coverage on vessels
Choose MSC-certified products from fisheries with transparent bycatch data, while recognising that MSC certification varies in quality across products
Support campaigns for emergency protections for the vaquita — the last opportunity to prevent the first cetacean extinction in decades