The significance of the Southeast Shoal of the Grand Bank to humpback whales and other cetacean species

Abstract

During June and July of 1982 and 1983 studies were made of the humpback whales on the Southeast Shoal of the Grand Bank of Newfoundland from a 13-m ketch. The humpbacks were found to concentrate on the central part of the shoal where surface and deep water temperatures were warmest and depths were shallowest, over concentrations of prey producing strong depth sounder traces. These traces were almost certainly made by spawning capelin. The humpbacks and prey traces dispersed as the season progressed. Other large whale species were much less numerous than the humpbacks, of which about 900 were estimated to use the shoal in 1982 and 1983. The Southeast Shoal humpbacks are a reasonably discrete segment of the Newfoundland–Labrador feeding stock, which winter in the West Indies, with the Southeast Shoal animals showing a particular preference for the waters off Puerto Rico. In 1982, individual whales were found to be generally moving slowly northwest over the shoal. Apart from forming very large coordinated groupings early in the studies, when the prey was most concentrated, the feeding and grouping behaviour of the humpbacks was similar to that in the inshore waters off Newfoundland.