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Cetacean distribution off Eastern Antarctica (80-150 °E) during the Austral summer of 1995/1996
journal contributionposted on 2023-02-07, 03:22 authored by D Thiele, Ed ChesterEd Chester, PC Gill
A line-transect marine science survey of the waters off East Antarctica (80-150 °E; CCAMLR Division 58.4.1; IWC Areas IV and V) was conducted during the Austral summer of 1995/1996. A total of 350 h search effort resulted in 342 sightings (746 animals) of 12 identified species and eight categories of unidentified cetaceans. Humpback whales (Megaptera novaeangliae) were the most frequently sighted species in terms of number of schools and number of individuals (82 sightings:159 animals). All humpback sightings were west of 120 °E; distributed over a wide latitudinal band from the ice edge out to the northern limit of the survey (63 °S); correlated with high integrated-Chl a (> 50 μm/m2); and generally concentrated in the waters to the south of the Antarctic Divergence and the Southern Boundary of the Antarctic Circumpolar Current (ACC). Baleen whale distribution reflected the overall patterns of biological productivity and oceanographic processes. Most animals were found to the west of 120 °E and to the south of the Southern Boundary of the ACC (which lies well offshore in this region) and the Antarctic Divergence, which coincided with the ACC between 85 and 135 °E on this survey. The large-scale patterns observed in this survey indicate that baleen whale species in the Southern Ocean may be concentrated in areas where extensive winter sea-ice cover and oceanographic features allow extended residence time in surface waters for primary producers during the Austral summer ice retreat. Odontocete species were less abundant and generally concentrated at meso-scale high-productivity areas produced by the interactions of identifiable physical features. (C) 2000 Elsevier Science Ltd.