Estimated Prey Consumption by Harp seals (Phoca groenlandica), Hooded seals (Cystophora cristata)

• Main Authors: Grey Seals (halichoerus Grypus, Harbour Seals, M. O. Hammill, G. B. Stenson
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Key words; feeding/food; grey seals; harbour seals; harp seals; hooded seals; Northwest Atlantic Ocean; Canada; Greenland; Newfoundland; atlantic cod; Cystophora cristata; Northwest Atlantic; Phoca groenlandica; Phoca vitulina
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.520.7661; http://journal.nafo.int/J26/Hammill.pdf

Consumption of prey by harp (Phoca groenlandica), hooded (Cystophora cristata), grey (Halichoerus grypus), and harbour (Phoca vitulina) seals in Atlantic Canada was estimated for the period 1990–96 by synthesizing and integrating information on indi-vidual energy requirements, population size, distribution and diet composition. Total an-nual consumption by these four species increased from 3.1 million to 4.0 million tons over the seven-year period. Seventy-seven percent (by weight) of the total prey consump-tion consisted of fish, of which capelin and sand lance were the dominant species ac-counting for 49 % (by weight) of the total fish consumed. The majority (74%) of total prey consumption occurred off southern Labrador and Newfoundland (Div. 2J and 3KL), fol-lowed by the northern Gulf of St Lawrence (Div. 4RS) (18%), and the eastern Scotian Shelf (Div. 4VsW) (4%). Harp seals were the most important predator, accounting for 82 % of total consumption, followed by hooded seals (10 % of total prey consumption), grey seals (7.8%), and harbour seals (0.2%). Regional differences existed in predation impacts of the four pinnipeds; harp seals were most important in Div. 2J and 3KL and in Div. 4RS, hooded seals were most important in Div. 2J and 3KL and Div. 3M (Flemish Cap), while grey seal predation predominated in the southern Gulf of St. Lawrence (Div. 4T) and on the Scotian Shelf (Div. 4VsW). Of the 3.1 million tons of fish consumed by the four species of seals in 1996, only about 20 % accounted for commercial species such as Greenland halibut (7%), Atlantic cod (6%), redfish (4%), and Atlantic herring (3%). Most of the consumption of these commercial species consisted of juveniles.