Spatial distribution of rorqual whales from the Gulf of St. Lawrence , Quebec , Canada


The spatial distribution of four species of rorqual whales was studied along the north shore of the Gulf of St. Lawrence during the months of June to October from 1989 to 2000. A research effort of 6511 hours at sea yielded 849 sightings of blue whales ( Balaenoptera musculus ), 5291 of finback whales ( B. physalus ), 3822 of humpback whales ( Megaptera novaeangliae ) and 6489 of minke whales ( B. acutorostrata ). Spatial and behavioural data were collected at sea using rigid-hulled inflatable boats, and GPS were used to obtain accurate positions. These data were plotted and analysed using GIS software to test the hypotheses that patterns of distribution were not random, were associated with bathymetry and reflected specific differences in habitat use. The resulting maps illustrated the clustered distribution or rorqual whales linked to sea-bottom topography, probably associated with areas of local upwelling, increased productivity and concentration of prey. Blue and fin whales shared almost the same distribution, humpback whales were found in slightly deeper, offshore waters whereas minke whales were more abundant in shallower waters. Little attention had been given until now to local patterns of distribution in the area and such information can therefore be potentially useful for practical management considerations. The results also emphasised the importance of scale in ecological studies of marine mammals and the need for further research using additional oceanographic parameters to understand habitat selection.

Doniol-Valcroze, T., R. Sears and D. Sergeant. 2001. Spatial distribution of rorqual whales from the Gulf of St. Lawrence, Quebec, Canada . Poster presented at the 14th biennial conference on the Biology of Marine Mammals, Vancouver , Canada , November 28 – December 3, 2001.