Building Energy Reserves

  • 12 / 11 / 2015 Par Marie-Sophie Giroux

    Fin whales in the Gaspé and Côte-Nord regions, minke whales and harbour porpoises off Charlevoix and the Côte-Nord, belugas at the mouth of the Saguenay River and in the Estuary; whales are being seen all along the St. Lawrence this November. What are they doing still here? The beluga is a resident of the St. Lawrence and will soon leave this sector to another part of the river which remains unknown, but as for the other “migratory” species, what’s the story? Well, as during the high season, the whales are taking advantage of food resources and stocking up on fats in anticipation of the winter months, when they substantially reduce their consumption during migration and reproduction.

    This energy reserve will be much needed to make the long journey to their wintering grounds and give birth! Amongst the minke whales seen in Franquelin this week, they were probably females… as are most of the individuals that frequent the St. Lawrence. Some of them are perhaps about to give birth in the coming months. After calving comes nursing. Will we see the young minke whale with her mother next summer?

    Not likely. Mother-calf pairs separate as soon as the latter is weaned, which is generally before reaching their summer feeding grounds. This bond in the minke whale, which lasts about 4-5 months, is the shortest of all baleen whales. The longest is that of the humpback, where the bond lasts up to a year, or sometimes as long as two. Since 2004, the MICS has observed a rise in mother-calf pairs of humpbacks in the St. Lawrence. Tic Tac Toe is a female that was seen twice with calves in the Estuary in 2007 and 2012, and this summer the humpback whale Quill was accompanied by her calf in the Gaspé.

    In many tooth whales, the relationship between the mother and her young extends beyond nursing, as is the case of belugas (see the question from the public) or certain populations of killer whales. In this species, young will even spend their entire lives with their mother, in a family unit in which the father is absent. Harbour porpoises mate between July and August, when they are abundant in the St. Lawrence. Births take place the following spring when they are back in the St. Lawrence, after a winter probably spent off the Atlantic Coast! Nursing lasts between 8 and 12 months. The harbour porpoise is one of the rare cetaceans that can give birth every year. Some contributors occasionally point out observing very small harbour porpoises… Could they be newborns? Perhaps…