Wild animals periodically encounter difficulties or suffer injuries that require human intervention and assistance. The natural assumption is that a surviving animal will, where viable, be released back to the wild. But is there a formal legal obligation for a rescuer to do so? This question arose recently in the context of ‘Morgan’, a female killer whale rescued in poor health in Dutch waters. Morgan was successfully restored to full health, but the Dutch authorities subsequently declined to repatriate her to the wild and, controversially, transferred her to a zoological facility in Spain. This article examines the largely unexplored legal obligations incumbent upon the Netherlands in respect of rehabilitated cetaceans, in the process exposing certain problems of clarity and consistency within the present regulatory framework. By necessary implication, this article identifies emerging issues of interpretation posed by the Morgan saga, illustrating the tensions between animal welfare and nature conservation – especially in the transboundary context – and concluding firmly that the Dutch authorities erred legally in making their final decision.