Bluefin Tuna Welfare in Ranching and Aquaculture

Atlantic bluefin tuna ranching and aquaculture raises serious welfare concerns from capture stress, transport to cages, crowding and slaughter of highly mobile fish.

Key Facts

Atlantic bluefin tuna is CITES-listed and subject to ICCAT quota management
Tuna ranching captures wild juveniles and grows them to market size in offshore cages
Bluefin tuna require continuous swimming and are ram ventilators — cessation of movement causes death
Slaughter by ike jime (brain spike) is the highest welfare method but requires skill

Welfare Considerations

Capture of juvenile tuna by purse seine causes acute stress, physical injury and exhaustion. Transfer to sea cages confines fish with high site fidelity and enormous territory requirements to restricted spaces. In cages, tuna cannot swim at natural speeds, show stereotypic swimming patterns and face chronic crowding stress. Slaughter requires brain spiking followed by blood-letting and spinal cord destruction for optimal welfare and product quality — a skilled technique not universally implemented.

What You Can Do

Choose tuna products from MSC-certified fisheries rather than ranched tuna
Support ICCAT quota enforcement preventing overfishing that drives ranching
Donate to Humane Slaughter Association research on high-welfare tuna slaughter methods
Avoid products from ranched bluefin given welfare and conservation concerns