Behavioral responses of humpback whales, Megaptera novaeangliae (Cetacea: Balaenopteridae), to satellite transmitter deployment procedures

ABSTRACT

Tagging whales with implantable satellite transmitters creates the possibility of disturbing the animals. Between 2003 and 2005, behavioral observations of humpback whales during tag deployment operations were conducted off the coast of Brazil from the flying bridge of a speedboat. The speed achieved by each whale during pursuit was registered by GPS receivers onboard two inflatable zodiac boats. Respiratory frequencies were significantly lower (n = 15, p 0.05) before (mean = 0.89 ± 0.06 blows/min) compared with after (1.39 ± 0.15) tagging. The same effect was observed for the speed of each animal (mean = 10.96 ± 0.44 km/h and 12.54 ± 0.57 km/h; n = 13, p 0.05). Both variables were positively correlated with the duration of the pursuit (n = 21, r = 0.88, p 0.05; n = 13, r = 0.94, p 0.01) and with each other (n = 26, r = 0.65, p 0.01). Acute responses were observed in 50% of the 28 tag deployments. Pursuits were shown to generate a longer effect than tagging. We suggest that the behavioral changes presented here are short-term disturbances because the tagging operation ends quickly and is not a repeated procedure. However, protocols must be developed to guarantee the maintenance of the animals' welfare during operations.