Atlantic bluefin tuna ranching in the Mediterranean involves capturing wild juveniles and fattening them in sea cages, raising major welfare concerns about capture stress, crowding, and inhumane slaughter.
Atlantic bluefin tuna are among the most welfare-compromised fish in commercial aquaculture. Capture by purse seine involves violent crowding and net constriction, causing capture myopathy, internal bleeding, and acute physiological stress with high mortality. Confinement in sea cages restricts natural high-speed swimming, causing chronic frustration and abnormal behaviour. Slaughter by ice immersion or carbon dioxide exposure causes prolonged, painful death. Percussive or electrical stunning followed by immediate bleeding would dramatically reduce suffering but is rarely implemented.