Feeding grounds of the eastern South Pacific humpback whale population include the South Orkney Islands

Abstract

This paper reports on two photo-identified humpback whales (Megaptera novaeangliae) that were sighted in different years in the proximity of the South Orkney Islands, at the boundary between the Scotia and Weddell seas (60°54.5'S—46°40.4'W and 60°42.6'S—45°33'W). One of the whales had been previously sighted off Ecuador, a breeding ground for the eastern South Pacific population. The other whale was subsequently resighted in Bransfield Strait, off the western Antarctic Peninsula, a well-documented feeding ground for the same population. These matches give support to a hypothesis that the area south of the South Orkney Islands is occupied by whales from the eastern South Pacific breeding stock. Consequently, we propose 40°W as a new longitudinal boundary between the feeding grounds associated with the eastern South Pacific and western South Atlantic breeding stocks.

Keywords

• Humpback whale
• photo-identification
• breeding stocks
• migration
• South Orkney Islands
• Southern Ocean