Keeping dolphins and orcas in marine parks raises profound welfare questions. Evidence from decades of captive orca research has driven growing public opposition to marine mammal shows and captive breeding programmes.
Orca and dolphin captivity presents perhaps the clearest case of captive species whose needs cannot be met in any feasible human-made environment. The disparity between natural range requirements and the largest practical tank sizes is so enormous as to render welfare-positive captivity impossible for orcas. Captive orcas show collapsed dorsal fins, broken teeth from gnawing tank walls, and shortened lifespans that together indicate severe chronic welfare compromise. Documented aggression toward trainers and between animals reflects the frustration of social animals confined in inadequate groups. The educational and research contributions of marine parks must be weighed honestly against these welfare costs, and evidence suggests education effects are largely achievable through alternatives.