Occurrence of killer whales (Orcinus orca) and other cetaceans in Terra Nova Bay, Ross Sea, Antarctica

Abstract

AbstractDuring January and February 2004, data on presence and distribution of killer whales (Orcinus orca) and other cetaceans were collected by helicopter surveys along the coastline of Terra Nova Bay and adjacent localities (western Ross Sea, Antarctica). A total of 37 sightings of killer whale, of both B and C types, were recorded as well as 17 sightings of Antarctic minke whales (Balaenoptera bonaerensis), nine ofBalaenopteraspp., two of Arnoux’s beaked whale (Berardius arnuxii) and four of undetermined species. The type C killer whale was the most abundant, with 23 sightings, whereas we recorded type B only twice. Group size ranged between 1 and 30 animals, with an average of eight individuals. Seventeen killer whales were photo-identified and 13 resightings occurred during the study period. Killer whales showed a differential pattern in partitioning the study area. Their encounter rate was significantly higher (t-test = 2.6045,P< 0.05) in the northern area extending from Edmonson Point to the Campbell Glacier Tongue (encounter rate, ER = 0.031), compared to the southern area from Mario Zucchelli Station to the Drygalski Ice Tongue (ER = 0.003).