Estimated fish consumption by hooded seals (Cystophora cristata), in the Gulf of St. Lawrence

Abstract

Fish consumption by hooded s eals (Cystophora cristata) in the Gulf of St. Lawrence was estimated by bringing together information on individual energy requirements, population size, distribution and diet composition. Aerial surveys indicated that pup production had increased from 2006 (SE = 190) in 1991 to 3978 (SE = 974) in 1994. A Leslie Matrix population model suggested that the population had increased from 10 000-11 000 animals in 1991 to 11 000-16 000 animals in 1995, depending on the mortality rates used in the model. Individual daily energy requirements were estimated using the daily energy requirement, a daily growth increment, and the basal metabolic rate. Summing individual energy requirements over the period that hooded seals are thought to be in the Gulf of St. Lawrence, gave an increase in total fish consumption from 5100-5600 tons in 1991 to 5600-8400 tons in 1995. Assuming that the diet of the Gulf of St. Lawrence hooded seals was similar to that of animals collected off the Newfoundland coast, much of this consumption would have probably consisted of Greenland halibut (Reinhardtius hippoglossoides) and redfish (Sebastes sp.).