DIGESTIBILITY OF CRUSTACEANS AND CAPELIN IN HARP SEALS (PHOCA-GROENLANDICA)

Gross energy intake (GEI), apparent digestible efficiency (%;DE), and body-mass change were studied both in recently weaned and in subadult harp seals fed capelin (Mallotus villosus) and crustaceans (Parathemis to libellula and Thysanoessa sp.) ad lib. The median %DE of Parathemis to libellula (with a wet-weight energy density (ED) of 3.9 kJ/g) and T hysanoessa sp. (ED: 2.3 kj/g) was 81% and 83%, respectively, while the median %DE of capelin (ED: 8.6 kj//g) was 94% and 93% for subadult ha rp seals and one harp seal pup, respectively. No correlation between a ge and %DE was obtained (P > 0.05). Despite ad lib. access to the food , the harp seal pups were unable to maintain body mass while on a crus tacean diet, and it is therefore suggested that harp seal pups most li kely must supplement their crustacean diets with fish to maintain grow th.