Yellowfin tuna farming is technically challenging and raises significant welfare concerns around capture of wild juveniles, stocking density, and the welfare of obligate ram-ventilators.
Tuna welfare in aquaculture is severely compromised at multiple stages. Wild capture of juvenile fish causes extreme stress from purse seine encirclement and transfer to cage systems, with high mortality. Captive tuna unable to swim at full speed develop chronic stress from movement restriction. Cataracts in captive tuna appear to result from dietary deficiencies and cage impacts. The intensive effort required to capture and hold wild juvenile tuna commercially means any tuna ranching operation has substantial and difficult-to-mitigate welfare costs.