WINTER FEEDING INTENSITY OF NARWHALS (MONODON MONOCEROS)

Stomach contents from 121 narwhals (Monondon monoceros) harvested in the eastern Canadian High Arctic and West Greenland were used to quantify seasonal changes in feeding activity and prey selection. Stomachs collected from summer harvests were mostly empty with little evidence of recent feeding. Stomachs collected in late fall and winter harvests had considerable amounts of undigested material with evidence of recent feeding. In summer, Arctic cod (Arctogadus glacialis), polar cod (Boreogadus saida), and Gonatus squid spp. constituted the narwhal diet. In fall,Gonatus fabricii was the only prey item observed. In late fall and winter, Greenland halibut (Reinhardtius hippoglossoides) and G. fabricii were the dominant prey items, observed in 51% and 73% of stomachs collected, respectively. Greenland halibut taken by narwhals were on average 39 cm (SD 8) and 556 g (306) and G. fabricii were on average 23 g (15) with mean mantle lengths of 85 mm (24). The low diversity of prey species indicates narwhals have a restricted diet across all seasons. This study presents the first information on the winter diet of the narwhal and suggests Baffin Bay and Davis Strait are heavily utilized for feeding, in contrast to limited food intake during the summer period.

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