Exploring the impacts of physical variability in the Antarctic marine environment on baleen whale distribution: IWC – SO GLOBEC collaboration 2001 – 2002

Deborah Thiele¹, Edwin Chester¹, Sue Moore², Ari Friedlaender³, Ana Širovic⁴, John Hildebrand⁴

¹Marine and Migratory Wildlife Group, Deakin University, School of Ecology and Environment,

Warrnambool, VIC, Australia

²NOAA/AFSC/National Marine Mammal Laboratory; Seattle, WA, USA

³Duke University, Nicholas School of the Environment, Durham, NC, USA

⁴Scripps Institution of Oceanography/MPL; La Jolla, CA, USA

Cetacean visual surveys for the IWC were conducted on eight cruises during the SO GLOBEC studies in the WAP. The objective of these cruises was not to estimate absolute abundance of cetaceans, but rather to examine associations between the distribution and relative abundance of cetacean taxa, and physical features and processes, and with patterns in the distribution of other biota. These data provide a series of seasonal (late summer, autumn and winter) snapshots of one region over two years with very different ice conditions. The visual data are complimented by concurrent passive acoustic studies that extend the spatial and temporal sampling beyond the study region and cruise dates. The very different ice conditions in 2001 and 2002 provide a basis to explore the effects of variability in physical and biological processes on whale distribution and relative abundance. Although whale distributions varied somewhat between the two years, there was nevertheless a strong concordance of distribution in relation to biological processes that were linked to physical features in both years. These analyses require collaborative projects across the range of disciplines during the synthesis and analysis phase of US SO GLOBEC and will include:

• integration and comparative analysis of distribution and relative abundance for blue, fin, minke and humpback whales between new (passive acoustic) and established (visual survey) data collection methods;
• GIS models using multiple datasets (e.g., BIOMAPER II, CTD, ADCP, bathymetry, remote satellite sea-ice imagery) to elucidate the variables which best describe cetacean distribution;
• investigation of relationships/differences in diversity and abundance patterns between baleen whales, seabirds and other top predators with sea ice, prey and other physical and biological processes;
• modeling local and regional scale oceanographic processes with baleen whale distribution patterns throughout each season and year;
• scaling up data collected at the local scale (WAP) to investigate regional and circum-Antarctic variability in baleen whale distribution using passive acoustic, sea ice, krill data and historical/recent records (IWC sighting and catch data and existing time series from this and other regions of the Antarctic) of whale distribution.