Diets of hooded seals (Cystophora cristata) in coastal waters and drift ice waters along the east coast of Greenland

Abstract

To provide data on the diets of hooded seals (Cystophora cristata ) in the Greenland Sea, seals were collected for scientific purposes on expeditions conducted in the pack ice belt east of Greenland in September/October 1999 and 2003, July/August in 2000 (summer), and February/March in 2001 and 2002 (winter). The results from analyses of stomach and intestinal contents from captured seals revealed that their diet was comprised of relatively few prey taxa. The squid Gonatus fabricii and polar cod (Boreogadus saida ) were particularly important, whereas capelin (Mallotus villosus ) and sand eels (Ammodytes spp.) occasionally contributed more. These four prey items constituted 60 Á97% of the diet biomass. Gonatus fabricii was the most important food item in autumn and winter, whereas polar cod dominated the summer diet, with important contributions from G. fabricii and sand eels. The latter was only observed on the hooded seal menu during the summer period, whereas polar cod, which was an important component during the autumn survey, was almost absent from the winter samples. During the latter survey, capelin also contributed to the hooded seal diet. Samples obtained from hooded seals in more coastal waters indicated a more varied diet based on fish such as polar cod, redfish (Sebastes sp.) and Greenland halibut (Reinhardtius hippoglossoides ).

Sources of variation in diets of harp and hooded seals estimated from quantitative fatty acid signature analysis (QFASA)

“…Although sample sizes were small, we found large-scale regional differences in hooded seal diets as well, confirming general conclusions from stomach-content analysis (e.g. Hammill & Stenson 2000, Haug et al 2007) and suggesting that spatial effects are an important component of hooded seal diet breadth.…”

“…Amphipods have been reported in high frequencies in stomach contents of both seal species (e.g. Sergeant 1991, Lawson et al 1995, Haug et al 2007); however, it has always been difficult to quantitatively assess their contribution to the overall diet. The large contribution of Atlantic argentine to hooded seal diets was , which are well within the diving and foraging range for these predators (Folkow & Blix 1999).…”

Intersexual differences in the postbreeding foraging behaviour of the Northwest Atlantic hooded seal

“…Separation between sexes in mean dive depths would reduce intraspecific competition at the vertical scale (Baird et al 2005). Detailed information on the diet as well as on the distribution and abundance of potential prey of hooded seals in our study area are lacking, but in other areas they feed on capelin Mallotus villosus and Greenland halibut Reinhardtius hippoglossoides, which are known to be abundant during summer in the area (Gascon 1995, Hammill & Stenson 2000, Bourdages et al 2002, Haug et al 2007). Since larger fish generally occur at deeper depths than smaller fish (Macpherson & Duarte 1991, Chouinard & Swain 2002, larger males may feed on larger prey than females.…”

“…The change in dive depths may be related to changes in prey species as animals began feeding on ice-associated prey such as polar cod Boreogadus saida, capelin Mallotus villosus, or young squid Gonatus sp. that are known to occur in the upper part of the water column in this region (Folkow & Blix 1999, Haug et al 2007). Upon arrival in Greenland, females and males spent less time overall diving and shifted diving effort to nighttime.…”

Under-ice distribution of polar cod Boreogadus saida in the central Arctic Ocean and their association with sea-ice habitat properties

“…Polar cod is considered an ecological key species in the Arctic Ocean due to its pan-Arctic distribution (Bouchard and Fortier 2011), large standing stocks (Geoffroy et al 2011;Hop and Gjøsaeter 2013) and its role as an energy transmitter to higher trophic levels Hop et al 1997a;Harter et al 2013), Along the Arctic shelves, polar cod are often recorded below sea-ice in autumn and winter (Benoit et al 2008;Geoffroy et al 2011). According to Welch et al (1993), the sea-ice may offer protection against marine mammals and predatory sea birds for which polar cod is known to be an important food source (Bradstreet and Cross 1982;Lønne and Gabrielsen 1992;Welch et al 1992;Haug et al 2007). When the ice melts, they become part of the bentho-pelagic stock (FalkPetersen et al 1986;Hop et al 1997b;Hop and Gjøsaeter 2013).…”