ESR 3:77-94 (2007)  -  doi:10.3354/esr003077

Lipid and gross energy content of North Atlantic right whale food, Calanus finmarchicus, in the Bay of Fundy

Josée Michaud1,2,*, Christopher T. Taggart1

1Department of Oceanography, Dalhousie University, 1355 Oxford Street, Halifax, Nova Scotia B3H 4J1, Canada
2Present address: Québec-Océan, Pavillon Vachon, Université Laval, Québec, Québec G1K 7P4, Canada

ABSTRACT: We address spatial and temporal distribution of abundance, lipid and caloric content and water column energy density of the copepod Calanus finmarchicus, a major food source for the north Atlantic right whale (NARW) Eubalaena glacialis in a primary feeding habitat—Grand Manan Basin, Bay of Fundy. The focus is on the lipid-rich diapausing copepodite stage 5 (C5) that dominates the zooplankton community during the summer and autumn whale-feeding period. We show that from May through July 2002, monthly averages of depth-integrated zooplankton wet biomass (<0.5 g m–3) and C5 concentration (<160 m–3), copepodite energy content (<2.5 J) and gross energy density (<0.5 kJ m–3) are low and reach their maxima (1.23 g m–3, 870 m–3, 3.5 J, and 3 kJ m–3, respectively) in September through October. The C5s represent the majority of the zooplankton and 84% of total zooplankton energy density is attributable to the wax ester content of C5s, of which there are 2 and perhaps 3 generations annually. Using right whale sighting per unit effort data in 2002, it is readily apparent that the whales occupy the Grand Manan feeding habitat in direct proportion (r2 > 0.88, p < 0.05) to the abundance and quality (i.e. energy density) of food available in the habitat. Thus, a water column-integrated energy density of 3 kJ m–3 appears to be a reasonable minimum estimate of that needed to define a right whale feeding habitat, though subject to spatial and temporal variation. Accordingly, inter-annual variation in the abundance and energy content of C5s will influence right whale feeding success and may influence arrival at and departure to and from, as well as seasonal residency in, primary feeding habitats. We suggest that prey field examinations and estimates of the type presented here should advance insights concerning the nature and location of other potential habitats as well as variation in right whale condition and reproductive capacity.

KEY WORDS: Right whale · Calanus finmarchicus · Copepod · Lipid · Energy content · Prey field

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