Journal of the Marine Biological Association of the UK



Research Article

Boat traffic affects the acoustic behaviour of Pacific humpback dolphins, Sousa chinensis


Sofie M.  Van Parijs a1p1 and Peter J.  Corkeron a2
a1 Norwegian Polar Institute, Tromsø N-9296, Norway
a2 School of Tropical Environment Studies and Geography, James Cook University, Townsville, QLD 4811, Australia

Abstract

In this study, the indirect (i.e. boats not involved in dolphin viewing activities) impacts of boat traffic on the acoustic behaviour of Pacific humpback dolphins, Sousa chinensis, were assessed in Moreton Bay, Australia. Humpback dolphin acoustic behaviour is affected by transiting boat traffic. Boats' passage did not affect the rates at which dolphins produced click trains and burst pulse vocalizations. However, dolphins significantly increased their rate of whistling immediately after a boat moved through the area. This increase occurred only when boats were less than 1·5 km from the groups. Groups including mother–calf pairs showed an increase in whistles in response to boats' passage. Groups with no calves produced significantly fewer whistles. This evidence suggests that the noise from transiting vessels affects dolphins' group cohesion. Mother–calf pairs appear to be most disturbed by transiting vessels, and exhibit an increased need to re-establish vocal contact.

(Received November 30 2000)
(Accepted April 11 2001)


Correspondence:
p1 Norwegian Institute of Fisheries and Aquaculture, N-9291 Tromsø, Norway. E-mail: sofie@npolar.no