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 &plusmn; 0.06 blows/min) compared with after (1.39 &plusmn; 0.15) tagging. The same effect was observed for the speed of each animal (mean = 10.96 &plusmn; 0.44 km/h and 12.54 &plusmn; 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

The effect of close approaches for tagging activities by small research vessels on the behavior of humpback whales (Megaptera novaeangliae)

“…In this study, we were able to account for variability in approach speed and maneuverability (by dividing the approach type into Cat1 and Cat2), but the sample size was not large enough to take the length of time of approach into account, nor any difference in behavior between those that were successfully tagged and those that were not. Increased speeds and directional changes in response to approaching vessels have been reported previously in humpback whales (Au and Green 2000, Scheidat et al 2004, Morete et al 2007, Alves et al 2010 and other cetacean species such as bowhead whales (Balaena mysticetus) (Richardson et al 1985), killer whales (Orcinus orca) (Williams and Ashe 2007), Indo-Pacific bottlenose dolphins (Tursiops aduncus) (Steckenreuter et al 2011), and fin whales (Jahoda et al 2003), indicating that our findings are relatively common responses to close approaches by small vessels amongst cetaceans. The use of maneuverability and changes in course by humpback whales to Cat2 approaches are similar to avoidance tactics used by humpback whales against predators, such as killer whales, which they are unable to out-swim (Ford and Reeves 2008).…”

“…, Alves et al . ) and other cetacean species such as bowhead whales ( Balaena mysticetus ) (Richardson et al . ), killer whales ( Orcinus orca ) (Williams and Ashe ), Indo‐Pacific bottlenose dolphins ( Tursiops aduncus ) (Steckenreuter et al .…”

“…Potential disturbance of cetaceans from research vessels may be dependent on several factors, such as speed of approach, duration of approach, and angle of approach (Watkins , Alves et al . , Stimpert et al . ).…”

“…Potential disturbance of cetaceans from research vessels may be dependent on several factors, such as speed of approach, duration of approach, and angle of approach (Watkins 1981, Alves et al 2010, Stimpert et al 2012. Group composition has also been found to be an important factor when looking at behavioral responses.…”