Chance Occurrence Or Shifting Baseline?

For the second time in two weeks, a Leopard seal has been found stranded on the beaches of Australia near Sydney. This is an incredibly rare event since Leopard seals are Antarctic ice dwellers which seldom wander further north than Macquarie Island. Both the male seal found last week and the female discovered yesterday showed signs of attack by Cookie-cutter sharks. This pair of Leopard seals joins five other sub-Antarctic fur seals that have also been found washed up on Australia's New South Wales coast this year

Leopard seals (Hydrurga leptonyx) are large and muscular true seals, with dark grey backs and light grey on their stomachs. Their throats are whitish with the black spots that give the seals their common name. Leopard seals are the second largest species of seal in the Antarctic (after Southern Elephant Seals), and are keystone predators. Young Leopard seals likely feed on krill swarms in the Antarctic seas, but adults have been observed preying upon fish, King, Emperor, and Chin-strap penguins and, less frequently, other seals such as Crabeater Seals. They have unusually loose jaws that can open more than 160 degrees allowing them to bite larger prey.

Asked to speculate on the appearance of these Antarctic species in Australian waters, Geoff Ross, a wildlife management officer with the National Parks and Wildlife Service suggested that Southern Ocean storms may have driven the pair north.

However, another possibility suggested is a disruption in the seal's normal Southern Ocean food supply, forcing them to hunt further afield. Mr Ross suggests the culprit may be that climate change had reduced the Antarctic food chain. "It's still a bit of a mystery," he said. "We can hypothesize about why the seals are here, but we really don't have good solid answers."