Marine mammals in captivity face fundamental challenges related to space, social complexity, and cognitive needs. Reform movements have improved standards while debate continues about whether any captivity can meet their welfare needs.
The welfare evidence for cetacean captivity is now substantial and largely unfavourable. Wild orca home ranges exceed 200 kilometres per day; the largest captive tanks are measured in hundreds of metres. The social complexity of orca family pods - with lifelong family bonds and matrilineal social structure - cannot be replicated in facilities with small numbers of unrelated individuals. The physical sign of collapsed dorsal fins is observed in virtually all captive male orca and represents a structural change caused by changed hydrodynamic forces in constrained spaces. Bottlenose dolphins show measurable stress hormone elevations and engage in begging, helpless behaviour, and stereotypy that are absent in wild populations. The argument that captivity supports conservation has weakened as evidence accumulates that most captive cetacean species do not face extinction and captive breeding rarely contributes to wild populations.