Tale 3 of whales

BY DAVID CAIRNS

Prince Edward Island is famous for lobsters, oysters and many other forms of marine life, but whales are not prominent among our salt—water attractions. But a recent influx of the big mammals off Murray Harbour shows that whales will indeed come here when the conditions are right.

For whales, conditions are right when there is lots of food, and they can catch that food. Each year, millions of herring spawn on Fisherman's Bank, a shallow plateau in the Northumberland Strait about 14 kilometers off Murray Harbour. The herring lay their eggs on the bottom in broad carpets that look, to a diver, like fields of newly— fallen snow. The egg beds can be several centimeters thick and cover many hundreds of hectares. To this inviting feast come hordes of cod, flounder, mackerel and cunners, all gorging themselves on the egg smorgasbord. And when the great whales arrive, the predators themselves become the prey.

I first saw whales on the Bank on 31 August this year, a day after beginning a spawning bed study for the Department of Fisheries and _0ceans. The whales were minkes (pronounced mink-ee). Minkes are small as whales go, and the biggest we saw were at most 9 meters long. The minkes were surfacing and diving in exactly the area where our echo— sounder showed the herring were concentrated, and the whales were doubtlessly filling themselves with herring and the other predators which came to fill their bellies with herring eggs. At the Same time, majestic gannets wheeled overhead in search of a herring or mackerel that strayed up in the water column, and gulls were in constant patrol for any bits of food that might find their way to the surface.

Our surveys on Fisherman's Bank continued until 20 September, and we saw minkes on most days. On some days there were probably a dozen or more of them on the Bank. Twice we saw fin whales as well. Fins, which are often more than 20 m long, are second only in size to the giant blue whale. The first sighting (on 2 September) was of a mother and her calf, and the second (on 10 September) was of a single adult.

To see whales surface to breathe is impressive, but to see them jump clear of the water is nothing short of spectacular. On 2 September, as we approached Murray Harbour at the end of the day, we were treated to the sight of a minke whale repeatedly breaching. The whale came hurtling from the water, and then fell back on the sea with a resounding splash. It repeated this process at least four times. The significance of breaching behaviour is uncertain, but it may have a communication function. Breaching is relatively common in humpback whales, which are abundant in Newfoundland waters, but it is unusual behaviour in minkes.

The waters of the northern Gulf of St. Lawrence and Newfoundland teem with seabirds and whales; why are these animals relatively

- 3 _