Sea Turtle Bycatch in Longline Fisheries

Longline fishing for tuna and swordfish accidentally catches and kills tens of thousands of sea turtles annually, making bycatch one of the leading causes of sea turtle mortality globally.

Key Facts

An estimated 200,000 loggerhead and 50,000 leatherback sea turtles are caught in longlines annually
Sea turtles caught on longlines often drown before lines are hauled; survivors may have hooks embedded in their digestive tracts
Circle hooks reduce sea turtle bycatch by up to 90% compared to J-hooks in some fisheries
Mackerel bait replacement with fish bait reduces leatherback bycatch significantly
Several turtle species including leatherback and loggerhead are listed as vulnerable or endangered partly due to bycatch

Welfare Considerations

Sea turtle bycatch causes both acute suffering and population-level harm to species that are already under severe pressure from multiple threats. Turtles that drown during longline sets die from asphyxiation; those that survive hooking may carry hooks that cause chronic injury, infection, and internal damage. The welfare harm is substantial and largely avoidable: circle hooks, bait switching, and improved handling protocols for accidental captures can dramatically reduce both mortality and suffering. These measures are cost-effective and in some fisheries now mandatory, but global implementation remains incomplete.

What You Can Do

Choose tuna and swordfish certified by programmes requiring circle hook use and bycatch monitoring
Support legislation requiring circle hooks and trained observers on longline vessels
Donate to sea turtle rescue and rehabilitation organisations
Advocate for expansion of turtle bycatch reduction requirements in international fisheries agreements
Reduce consumption of longline-caught tuna and swordfish where certified alternatives are unavailable