Behavior and salivary cortisol of captive dolphins (Tursiops truncatus) kept in open and closed facilities

Abstract

Few studies have been carried out on the welfare of captive bottlenose dolphins (Tursiops truncatus). Of these, most include information on animals kept in closed facilities or pools. The aim of this study was to assess the welfare of captive bottlenose dolphins in open and closed facilities by measuring states of individual behavior and salivary cortisol concentrations. A total of 23 bottlenose dolphins were studied in 4 different dolphinaria. Dolphinaria A and B have closed facilities, whereas dolphinaria C and D have open facilities. A total of 152 hours of behavioral observations were analyzed using a combination of behavior and scan sampling to obtain information on individual time budgets. Salivary cortisol concentrations were measured using radioimmunoassay in 96 and 180 saliva samples of dolphins kept in closed and open facilities, respectively. In general, the results found that dolphins kept in open facilities spent less time floating (P < 0.05) and swimming in circular patterns than linear ones (P < 0.05) compared with dolphins in closed facilities. Dolphins kept in open facilities also had lower salivary cortisol concentrations than dolphins kept in closed facilities (P < 0.05). For this reason, we suggest that further research should include other welfare indicators such as reproductive function and health measurements to know more about the relationships between the design of pools and dolphin welfare.