Model estimates of pre- and post- abundances of the cetaceans in the Antarctic Ecosystem

IWC document SC/68D/EM/WP04 provided a list of pre-exploitation estimates of abundance for the Antarctic blue, fin, humpback, minke, southern right, sei and Bryde’s whales in the region(s) south of 60°S, based on modelling studies. The authors were tasked with compiling this list as part of the intersessional steering group on the ecosystem functioning of cetaceans in the Southern Ocean. This document summarises what has been accomplished for this task (last presented to the IWC Scientific Committee in April 2023), as well as providing updates to this work through considering prey carbon content and ‘whale falls’. Both the Moosa and Tulloch ecosystem models estimate the present large baleen whale biomass south of 60°S to be about 20% of its value before exploitation commenced.