Palaeoecology and the History of Exploitation: a Retrospective Template for
Understanding Baleen Whale Ecology in the Southern Ocean

Deborah Thiele (A preliminary presentation of a review paper in collaboration with many other authors)

Collaboration between the International Whaling Commission and Southern Ocean GLOBEC aims to investigate the scale of ecological linkages between cetaceans and the physical-biological regime of the Antarctic. Consideration of information at several time scales (current, evolutionary, recent historical) is a critical element in this process. The evolution of mysticetes is linked to palaeoecological events, particularly the formation of a circumpolar current around the Antarctic continent in the Early Oligocene (32 - 37ma). This event had a major impact on physical regimes in the region, potentially playing a primary role in shaping its ecology. The evolution of mysticete feeding apparatus and diversification occurred in a similar geological time frame and reinforces the interdependence of these high level predators with both the biological and the physical cycles in this region. Early explorers reported the high biomass of baleen whales in austral summer, and the commercial exploitation that followed resulted in the removal of more than 90% of each of the large baleen whale species. In essence a huge experiment has been conducted, with implications for trophic dynamics and the functioning of the ecosystem, which we have yet to determine. This review of available cetacean data from the past for autumn-winter provides a context for the current collaborative research.