Yellowfin tuna are among the world's most valuable commercial fish, caught by purse seine, longline, and pole-and-line methods. Each method has distinct welfare implications, and tuna ranching raises additional concerns.
Yellowfin tuna welfare varies dramatically by capture method. Pole-and-line fishing — where individual fish are hooked and rapidly retrieved — causes the least prolonged suffering and minimal bycatch. Purse seine nets encircle hundreds of thousands of fish in extreme crowding conditions, causing thermal stress, injury, and prolonged suffering before hauling and killing. Fish aggregating devices (FADs) concentrate mixed species for purse seine capture, increasing bycatch welfare impacts. Tuna ranching involves capturing wild juvenile fish and holding them in sea cages for months — obligate ram ventilators in confined spaces experience profound welfare compromise. At slaughter, ike jime (brain spiking) is the most welfare-positive method used for premium sashimi tuna; industrial processing typically uses asphyxiation or gill-cutting without prior stunning. Consumer choice of pole-and-line or skipjack tuna over purse-seine-caught yellowfin has direct welfare and environmental impact.