Can We Assess Marine Mammal Welfare in Captivity and in the Wild? Considering the Example of Bottlenose Dolphins

The welfare of a range of terrestrial animals can now be objectively estimated thanks to the well established, but still expanding, field of welfare science. Despite continuing difficulties regarding definitions, it is generally agreed that welfare is assessed most accurately using multiple animal-based measures that is, those evaluating aspects of the animal itself such as its behaviour. In addition, scientists combining behavioural, physiological, and cognitive animal-based indicators of welfare have found this approach is superior to using one-dimensional measures. But can the same approaches be used for marine mammals, and would assessments of their welfare have the same relevance in captivity as in wild environments? There is no reason why not, and we review the past decades of marine mammal research relevant to welfare, as well as the more recent advances in the field where this topic is starting to be addressed directly. We then use the example of bottlenose dolphins (Tursiops truncatus) to examine what the measures within an all-encompassing (i.e., comprehensive) welfare assessment might look like. Looking to the future, we suggest directions for developing assessments for captive animals and explore how protocols might differ in wild settings. In conclusion, we find that the first steps are being made towards objectively assessing marinemammal welfare in captivity - through application of terrestrial animal approaches as well as through novel paradigms. Regarding bottlenose dolphins, several welfare measures have been proposed and should now be further validated and applied. It is hoped that this review will encourage continued research in marine mammal welfare assessment given the demonstrated initial achievements of bottlenose dolphin welfare studies and the potential for application to many different captive and wild contexts.