Geoscience Reference
In-Depth Information
NORTHERN KRILL
Blue whales are the largest animals ever known to have lived on Earth, reaching lengths of 30 meters (100
feet) and weighing as much as 75 tonnes. They are found in all of the world's oceans and migrate seasonally,
usually moving toward the poles in the spring to take advantage of the high zooplankton production there in
summer. In some cases they may form relatively discrete feeding populations, migrating together from one
area of high productivity to another. Although there is some evidence suggesting that the Davis Strait and Gulf
of St. Lawrence whales belong to the same population, acoustic tracking of blue whales indicates that they
may range over the entire North Atlantic ocean basin and therefore may comprise a single stock, a question
only genetic analysis may be able to answer.
What we do know is that blue whales are present in the Gulf of St. Lawrence for most of the year. They are
forced to leave in early winter, however, to avoid entrapment in ice and do not return until ice breakup in the
spring. There are two peak periods for their presence along the North Shore: one in early April to early June,
and another from August until late October. They are very nomadic and rarely spend more than ten days feed-
ing in a particular area. In addition to Quebec's North Shore, they have been sighted in areas off the Gaspé
Peninsula, around Anticosti Island, and in the St. Lawrence River estuary as far upriver as Tadoussac.
Stomach content analysis has shown that the food of blue whales in the North Atlantic consists entirely of
krill, relatively large euphau-siid crustaceans. Two species, Thysanoessa raschii and Meganyctiphanes norve-
gica, are particularly important food sources in the gulf. During the daylight hours, blue whales are frequently
observed feeding along the North Shore's 100-meter (300-foot) contour, where krill are concentrated.
Fortunately for blue whales, humans do not compete with them for their prime food source, which has no
commercial value. The great whale's numbers were severely depleted by whaling, however, especially in the
second half of the 19th century, when steam-powered vessels carrying deck-mounted harpoon canons came in-
to wide use. Blue whales in the North Atlantic were finally given full protection in 1955, but by then the popu-
lation had been decimated. It has been estimated that perhaps as many as fifteen hundred blue whales were
found in eastern Canadian waters when modern whaling began. (Some studies have suggested that as many as
fifteen thousand may have ranged the entire North Atlantic in the pre-whaling period.) By the early 1960s,
their numbers were in the very low hundreds at most. By the mid-1990s, some 350 individuals had been photo-
identified in Canadian and New England waters, of which 320 were identified in the Gulf of St. Lawrence. But
in nineteen seasons of observation, only nine blue whale calves were observed along the North Shore. A num-
ber of explanations might account for their low presence: it could be that lactating females prefer other areas,
or that weaning occurs before the whales arrive along the North Shore, or—the worst-case scenario—that few
calves are being produced in the population, for reasons that are not well understood.
THE MINGAN ARCHIPELAGO
consists of fifteen islands and forty or more islets that stretch for 80 kilometers
(50 miles) between the North Shore of Quebec and Anticosti Island, in the Jacques Cartier Channel. Many
have been sculpted by water and ice into limestone monoliths, or flower pots, which the great Quebec botanist
Brother Marie-Victorin colorfully described as “daughters of the sea.” The tides, currents, and ice continue to
sculpt them into ever-changing shapes.
The islands' steep cliffs and their isolation make them attractive to breeding seabirds, including gulls, terns,
eiders, and 35,000 pairs of Atlantic puffins. However, it is the plants that are the most remarkable biological
feature of the islands.
