The impact of food enrichment on the behavior of cownose ray (Rhinoptera bonasus) kept under human care

Abstract

The cownose ray (Rhinoptera bonasus) faces vulnerability primarily due to unregulated fishing, resource overexploitation, and habitat degradation. Consequently, individuals maintained under human care play a pivotal role in species conservation, particularly when their welfare is prioritized. Achieving optimal welfare in aquarium settings relies heavily on effective management practices, notably environmental enrichment. However, research on the efficacy of such techniques for cownose rays remains limited. Thus, this study sought to evaluate the impact of various food enrichment items on the behavior of four individuals at the São Paulo Aquarium in Brazil. The project encompassed three phases: baseline, enrichment, and post-enrichment. Enrichment items, designed to mimic the species’ natural foraging behavior, included an ice block containing food, food hidden in vegetables fixed to structures at the bottom of the tank, a tray with substrate and food, and a perforated plastic container with food inside. Behavioral observations utilized focal sampling with instantaneous recording every minute. Results showed increased foraging activity in the post-enrichment phase, whereas swimming increased and following behaviors decreased during the enrichment phase. Additionally, foraging behaviors predominantly occurred near the aquarium bottom. Overall, findings suggest that enrichment items effectively stimulated natural behaviors in cownose rays and were very attractive to the fish, advocating for their integration into species management protocols to enhance welfare.