The Effects of Early Life Experience on Behavioural Development in Captive Fish Species

The fate and movements of aquarium-released giant trevally Caranx ignobilis inferred from acoustic telemetry

Movements of four adult giant trevally Caranx ignobilis were tracked using passive acoustic telemetry after being released from uShaka Sea World Aquarium in Durban, South Africa, where they had been kept on display for a period of 8 years. All four individuals were detected on a large network of deployed acoustic receivers for a minimum of 3 months to a maximum of over 6 years. Their movements were compared to 43 wild-caught and tagged C. ignobilis over a similar period and two individuals adopted movement behavior similar to that of their conspecifics, including repeated annual seasonal migrations to a known spawning aggregation site. This study shows that with good animal husbandry, indigenous fish kept in captivity can be released back into the wild and not only survive but adopt natural movement behavior and contribute to future generations of their species.

Physical enrichment research for captive fish: Time to focus on the DETAILS

Growing research effort has shown that physical enrichment (PE) can improve fish welfare and research validity. However, the inclusion of PE does not always result in positive effects and conflicting findings have highlighted the many nuances involved. Effects are known to depend on species and life stage tested, but effects may also vary with differences in the specific items used as enrichment between and within studies. Reporting fine-scale characteristics of items used as enrichment in studies may help to reveal these factors. We conducted a survey of PE-focused studies published in the last 5 years to examine the current state of methodological reporting. The survey results suggest that some aspects of enrichment are not adequately detailed. For example, the amount and dimensions of objects used as enrichment were frequently omitted. Similarly, the ecological relevance, or other justification, for enrichment items was frequently not made explicit. Focusing on ecologically relevant aspects of PE and increasing the level of detail reported in studies may benefit future work and we propose a framework with the acronym DETAILS (Dimensions, Ecological rationale, Timing of enrichment, Amount, Inputs, Lighting and Social environment). We outline the potential importance of each of the elements of this framework with the hope it may aid in the level of reporting and standardization across studies, ultimately aiding the search for more beneficial types of PE and the development of our understanding and ability to improve the welfare of captive fish and promote more biologically relevant behaviour.