🎣 Deep Sea Fishing & Animal Welfare

Trawling, Decompression, Bycatch, and the Hidden Welfare Crisis

The Scale of Wild-Catch Fishing

Wild-catch fishing kills more animals by weight than any other human industry — an estimated 0.8 to 2.3 trillion fish annually, plus hundreds of billions of crustaceans and other marine animals. Yet fishing receives minimal welfare scrutiny compared to land-based animal industries.

1–2T
Wild fish killed per year
40%
Global catch that is bycatch (discarded)
80%
World's fisheries fully or over-exploited
600M
People depending on fishing for livelihoods

Welfare Harms in Commercial Fishing

Decompression Injury

Barotrauma: Fish caught by trawl from deep water experience rapid pressure change as they ascend. This causes expansion of the swim bladder, which can rupture abdominal organs, protrude through the mouth, and cause eye prolapse ("pop-eye"). Fish experiencing severe barotrauma may be unable to descend if released, dying slowly at the surface.

Asphyxiation

Slow suffocation: Most commercially caught fish are killed by suffocation — left to die on ice or on deck after landing. This can take minutes to hours depending on species. Fish show behavioral indicators of distress during this process.

Trawl Net Stress

Crowding and crushing: In bottom trawls, thousands of fish are crowded into the cod end of the net under pressure from the weight of the catch above. Physical injuries, scale loss, and extreme stress occur during the trawling process (which can last hours).

Longline Bycatch

Prolonged suffering: Longline fishing (lines with thousands of baited hooks) frequently catches non-target species including seabirds, sea turtles, sharks, and dolphins. Animals may remain alive but injured on hooks for many hours before lines are retrieved.

Specific High-Welfare-Concern Methods

Bottom Trawling

Bottom trawling — dragging weighted nets across the seafloor — destroys seafloor habitats and catches enormous quantities of non-target species. It is both the most ecologically destructive and arguably the most welfare-harmful commercial fishing method. The EU partially restricted deep-sea bottom trawling in protected areas in 2023.

Gill Nets

Gill nets entangle fish (and non-target animals including marine mammals and seabirds) by their gills. Entangled animals may drown or remain trapped for hours to days.

Purse Seine for Tuna

Purse seine nets encircle entire schools of fish. When associated with Fish Aggregating Devices (FADs), they generate high bycatch of juvenile tuna, sharks, rays, and sea turtles.

Lower-Harm Fishing Methods

Hook-and-line: Rod-and-reel and handline fishing are highly selective, with minimal bycatch and the ability to release non-target species quickly.
Pole-and-line tuna: Pole-and-line fishing for tuna has near-zero bycatch compared to FAD-associated purse seining. "Friend of the Sea" and MSC pole-and-line certified tuna is the highest-welfare commercially available option for canned tuna.
Ike jime: Traditional Japanese method of immediately killing fish by spiking the brain — causes near-instant death, eliminating the prolonged suffocation of standard commercial landing. Increasingly adopted by premium fish markets and welfare-conscious fishers.

Reform Priorities

What You Can Do