Geoscience Reference
In-Depth Information
A harp seal suckles its pup on the birthing ground of a Gulf of St. Lawrence ice floe.
Harp seals are cold-water animals well-suited to the North Atlantic, where there are three stocks: New-
foundland, Jan Mayen Island, and the White Sea. The Newfoundland stock is further divided into two sub-
stocks, one which whelps in the Gulf of St. Lawrence and the other at the so-called Front, east of Labrador and
northeast of Newfoundland. These stocks are not separate genetically, and although they intermingle, they
maintain a Front-to-Gulf ratio of 2:1, probably related to relative amount of whelping habitat. The greatest
year-to-year changes in this ratio are due to fluctuating ice coverage in the gulf, which may be thick or almost
absent, depending upon climatic conditions.
In late autumn, mature seals migrate from their Arctic summering grounds, near Baffin Island and the west
coast of Greenland, to feed primarily on capelin in the gulf for two to three months before the breeding season.
Animals that breed near the north shore of Prince Edward Island, for example, may migrate 3,000 kilometers
(1,860 miles) during their annual cycle. It has been shown that all animals that winter in the gulf were born in
the gulf. However, many gulf-born immatures—one-to-three-year-olds—winter on the Front, where there are
higher biomasses of capelin. In summer, though, the prime feeding area for young-of-the-year harp seals is in
the estuary, where they also feed on capelin. The only area where harp seals feed predominantly on herring is
near the Magdalen Islands.
