Atlantic bluefin tuna are apex predators and highly intelligent fish that have been heavily overfished. Their welfare in both wild fisheries and the emerging ranching industry deserves serious consideration.
Bluefin tuna welfare in fisheries interactions involves significant acute stress and injury. Their endothermy and active physiology make them particularly vulnerable to capture stress — exertion during fight-on-the-line elevates body temperature and lactate levels, causing physiological damage analogous to severe athletic injury. Longline capture kills many non-target individuals. Purse seine capture in crowded nets causes crowding stress. Ranching captures wild juveniles — a population draw on wild stocks — and confines highly mobile animals in sea cages. The cognitive sophistication indicated by bluefin tuna behaviour, memory, and learning capacity suggests their welfare experience during capture and confinement may be significant. Sustainable fishing quotas and reduction of bycatch mortality are the most critical welfare and conservation interventions.