Journal Article

Spring diet of ringed seals (<i>Phoca hispida</i>) from northwestern Spitsbergen, Norway

Aili L. Labansen, Christian Lydersen, Tore Haug and Kit M. Kovacs

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 64, issue 6, pages 1246-1256
Published in print September 2007 | ISSN: 1054-3139
Published online July 2007 | e-ISSN: 1095-9289 | DOI: http://dx.doi.org/10.1093/icesjms/fsm090
Spring diet of ringed seals (Phoca hispida) from northwestern Spitsbergen, Norway

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Labansen, A. L., Lydersen, C., Haug, T., and Kovacs, K. M. 2007. Spring diet of ringed seals (Phoca hispida) from northwestern Spitsbergen, Norway. – ICES Journal of Marine Science, 64: 1246–1256.

Complete gastro-intestinal tracts (GITs) from 267 ringed seals from five different locations in Spitsbergen were collected during spring of the years 2002–2004. Diet was assessed based on hard part remains from prey. Invertebrates constituted <2% of all prey (relative frequency, Ni). Fish otoliths were found in all seals; 1.7, 34.3, and 64.0% of the recovered otoliths were found in the stomach, small and large intestines, respectively, emphasizing the importance of analysing the whole GIT, not only the stomach. Otoliths from stomachs and small intestines with minimal signs of erosion were measured to back-calculate pre-ingested prey size and biomass. Based on measured polar cod (Boreogadus saida) otoliths (n = 7007), the ringed seals fed on fish in the length range 44.4–229.2 mm, primarily consuming the youngest year classes. Adult females ate smaller polar cod more often than adult males or juveniles. Polar cod dominated the diet, with a frequency of occurrence (FO) of 100%, Ni of 71.9%, and a biomass contribution of 77.2%. The taxon Stichaeidae was the second most frequent prey type (FO = 55.6%) followed by Cottidae (FO = 35.6%). The diet of ringed seals from one locality markedly differed from the others, with a greater species diversity, low Ni of polar cod (15%), and a dominance of Stichaeidae (Ni = 67%). Location of sampling, as well as sex and age of the seals, had significant influences on ringed seal diet in spring.

Keywords: Arctic; Boreogadus saida; diet, foraging; marine ecosystem; Pusa; Spitsbergen

Journal Article.  7207 words.  Illustrated.

Subjects: Environmental Science ; Marine and Estuarine Biology

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