Preliminary review of killer whale (Orcinus orca) strandings on South American coasts south of 33°S.

RICCIALDELLI L.; R.N.P. GOODALL; J.D.. LOUREIRO; V. IRIARTE; S.G. MORÓN; N. GARCÍA

Cape Town, South Africa

Conferencia; 17th Biennial Conference on the biology of marine mammals; 2007

The Society for Marine Mammalogy

We reviewed the literature of southern South America and interviewed colleagues for strandings of killer whales, Orcinus orca, south of 33°S. One of the top predators of the world’s oceans, this is not a species which strands often in this region, but we were able to collect at least some information on strandings in each of the countries involved. Most strandings were of single animals, five strandings were of two animals, two of three, but the largest mass stranding, of at least 22 animals at Bahía San Sebastián in Tierra del Fuego in 1972, was probably caused when a pod was trapped by the rapidly receeding tide over the mudflats of this shallow bay.  We found a total of 92 strandings of which 73 were dead (22 just partial skeletons), and 19 were live strandings. Of six animals returned to the sea, one restranded. Four live strandings in different years were taken to the Oceanario Mundo Marino for rehabilitatiion; one died during transport, two lived for 5.5 and 12 years, and one is still alive after 15 years. Females ranged from 315-660cm in total length (n=10) and males 300-760cm (n=7). In view of these sizes, most animals were fairly young. Stomachs were examined for three animals; one was empty, one contained small black pebbles, and a female contained a whole penguin, Spheniscus magellanicus, part of an elephant seal and pieces of cetacean skin. Killer whales are well known to self-strand to capture pinnipeds at Península Valdés, but few stranded animals were found in that area. Although a number of strandings occurred on the north coast of Tierra del Fuego, no strandings were recorded on the south coasts, where predatory interactions have been observed with other cetaceans, steamer ducks and pinnipeds. (POSTER)