© 2006 International Council for the Exploration of the Sea
Seabird numbers and prey consumption in the North Atlantic
a Tromsø University Museum, Department of Zoology NO-9037 Tromsø, Norway
b Canadian Wildlife Service 1141 Route de l'Eglise, PO Box 10100, 9th Floor, Ste-Foy, Quebec G1V 4H5, Canada
c Norwegian Institute for Nature Research NO-7485 Trondheim, Norway
d Department of Arctic Environment, National Environmental Research Institute Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark
e Cognitive and Behavioural Ecology Programme, Memorial University of Newfoundland, St John's Newfoundland A1B 3X9, Canada
f JNCC Dunnet House, 7 Thistle Place, Aberdeen AB10 1UZ, Scotland, UK
g Biology Department, College of Staten Island 2800 Victory Boulevard, Staten Island, NY 10314, USA
*Correspondence to R. T. Barrett: tel: +47 7 764 5013; fax: +47 7 764 5520. e-mail: robb{at}tmu.uit.no.
We compared seasonal composition, abundance, and biomass of seabirds between the Northeast (ICES region) and Northwest (NAFO region) Atlantic fisheries regions to identify differences in community assemblage and prey consumption. Seabirds were more abundant in the Northwest Atlantic, but biomass was greater in the Northeast. This disparity resulted from enormous numbers of little auks Alle alle breeding in West Greenland and of Leach's storm-petrels Oceanodroma leucorhoa breeding in Newfoundland, plus large numbers of non-breeding shearwaters Puffinus spp. entering southern NAFO areas in summer. The Northeast Atlantic communities were dominated numerically by northern fulmars Fulmarus glacialis, large auks Uria spp., and the Atlantic puffin Fratercula arctica. Seabirds occupying the North Atlantic consume approximately 11 x 106 t of food annually. Overall consumption rates peak during summer as a result of increased breeding activity and seasonal movements of birds into the North Atlantic. Because of the greater biomass of birds in the northeast, consumption (mainly by piscivores) in ICES areas was approximately 20% higher than that in NAFO areas, where planktivores dominate. NAFO areas had, however, a much greater consumption rate per unit area than ICES areas. Comparative studies such as these could prove informative in assessing large predator responses to the influence of fishing and ocean-scale climate change.
Keywords: community, consumption, North Atlantic, predators, seabirds
Received 27 September 2005; accepted 9 April 2006.