Food and feeding ecology of the neritic-slope forager black-browed albatross and its relationships with commercial fisheries in Kerguelen waters

Food and feeding ecology of black-browed albatrosses Diomedea melanophrys rearing chicks was studied during 2 austral summers (1994 and 1995) at the Kerguelen Islands. Dietary analysis and satellite tracking were used to estimate potential interactions with commercial fisheries in the area. Fish comprised 73% by fresh mass of albatross diet; other significant food items were penguins (14%) and cephalopods (10%). Twenty-one species of fish (232 individuals) were identified and included mainly nototheniid and channichthyid species. The most important were Dissostichus eleginoides (18.3% by reconstituted mass), Channichthys rhinoceratus (16.9%), Lepidonotothen squamifrons (11.6%), and to a lesser extent, Bathyraja sp. (4.5%) and Notothenia cyanobrancha (4.5%). The cephalopod diet was dominated by 3 taxa, the ommastrephid squids Todarodes sp.(7.6%) and Martialia hyadesi (3.6%), and the octopus Benthoctopus theilei (2.4%). Satellite tracking indicated that during trips lasting 2 to 3 d, albatrosses foraged mainly over the outer shelf and inner shelf-break of the Kerguelen Archipelago. Birds moved to northern, eastern and southern waters, but never to the western Kerguelen shelf where there was a commercial longline fishery for D. eleginoides. Interactions with trawlers targetting D, eleginoides and Champsocephalus gunnari were of minor importance in the northern shelf. There, offal from D. eleginoides was available to the birds; fish and cephalopod bycatch were negligible. Most of the natural prey of black-browed albatrosses are primarily benthic and semipelagic organisms not known to occur near the surface. Since we demonstrate that most of them were not scavenged behind fishing vessels, the way albatrosses catch demersal organisms remains a mystery.