Summary
A line transect survey of the waters off East Antarctica (80°E-150°E; CCAMLR Division 58.4.1; IWC Areas IV &V) was conducted during January to March 1996 on the 5,000t icebreaker RV Aurora Australis. Cruise determining programs were a hydroacoustic survey to estimate Antarctic krill (Euphausia superba) abundance and an oceanographic program aimed at investigating and measuring the seasonal nature and evolution of oceanographic processes. A further primary objective of the cruise was to provide a platform of opportunity for a wide range of multidisciplinary programs for future integration of physical and biological data for input to ecosystem management. A cetacean sighting survey using standard double platform line transect methodology was included, with two main aims. To obtain estimates of abundance and distributional data to compare with historical records for this region, and to begin the process of investigating linkages between physical and biological processes and cetacean distribution and abundance in the Southern Ocean ecosystem. A clear broad scale difference between the western and eastern sections of the survey area was evident. Biological diversity and abundance were relatively high and spread over a wide latitudinal range (ice edge to 63°S) in the west, but much reduced east of 120°E and correlated to a thin band of upwelling along the ice edge. Biological patterns and processes were strongly linked to physical oceanographic features. Recirculation and upwelling of nutrient rich waters in the western region are apparently driven by the movements of Circumpolar Deep Water (CDW) along a broad front in the west at ~63°S, a new-found source of Cold Bottom Water off Adelie Land, and a gyre, bounded in the west and north by an arm of the Antarctic Circumpolar Current (ACC). In the east, nutrient-rich waters are confined to a thin band along the ice edge. The underlying oceanography also influences seasonal minima and maxima of sea