Environmental enrichment (EE) is increasingly used to improve the welfare of captive animals. Several studies reveal the benefits of EE in aquaculture settings but few of addressed the impacts on captive sharks. One way to assess the affective state of captive animals is to conduct judgement bias tests but they have rarely been applied in aquatic settings and never for sharks. Here we adapted a common judgement bias test and applied it to captive reared bamboo sharks (Chiloscyllium punctatum) to determine if EE would induce a positive affective state.
Subjects were trained to associate either a black or white target with a food reward in a two-choice setup. Once the association was made, the two targets were replaced with a single ambiguous target and their latency to approach was recorded. We expected that sharks housed in the enriched tank would have positive affective states and, therefore, learn the task more quickly and approach the ambiguous target faster than the sharks from the barren tank. While we found that enrichment did not have an apparent effect on learning ability or judgement bias due to a lack of power, 3 of the 8 sharks reached the learning criterion to transition to the judgement bias test. The low success rate was likely due to a lack of motivation and methodology limitations. Based on this experience, we provide recommendations for developing judgement bias test methodologies for captive sharks.