Measuring Acoustic Activity as a Method to Evaluate Welfare in Captive Beluga Whales (<I>Delphinapterus leucas</I>)

Abstract

Animal welfare evaluation is a difficult task. Behavioural and physiological parameters are commonly used, but their interpretation is not always robust. The study of vocal behaviour as an indicator of animal welfare has proven to be effective in some terrestrial captive mammals, but little is known about its application in marine mammals. The acoustic activity of two beluga whales (Delphinapterus leucas) was monitored during two procedures: (1) before and after air transportation to new facilities and (2) before and after the introduction of four harbour seals (Phoca vitulina) to the same facilities. After transportation, the underwater vocalization rate dropped dramatically, remained very low during the next 4 wks, and did not reach the same level as before the transport until the 5th wk. Similarly, the vocalization rate decreased just after the introduction of the harbour seals, and it remained low for 2 wks. The observed decrease in the acoustic activity of beluga whales in both situations and the persistence of this change through time suggest that the acoustic behaviour in this species is very sensitive to environmental stressors. We propose that observation of underwater acoustic activity in captive beluga whales is a potentially effective method to monitor stress level and adaptations to environmental changes in their facilities. This technique must be explored further since it could be valuable in cetacean management in oceanaria and rehabilitation centres.