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The Love Life of the Whales of the St. Lawrence

«Whales come here to fill their bellies. They then get together in the South in winter for spectacular courtship rituals, after which they mate and give birth». This wonderful story is true for but one of the thirteen species of whales encountered in the St. Lawrence: the humpback whale. So, what about all the others? We will spend the next two bulletins in an overview of this vast subject!

Many species of cetaceans chose the warm season and the waters of the St. Lawrence to mate and give birth. Obviously, the beluga whale, which resides here year round, doesn't have much choice! Newborns are seen all summer long swimming at their mothers' sides. As for mating, a few clues suggest that several male beluga whales form coalitions in order to «convince» a female to copulate. However, those of you with voyeuristic intent will be disappointed. It is extremely rare to observe beluga whales engaging in sexual activity. The few cases that have been reported mention groups of adults intensely active at the surface of the water. Beluga heads and tails, pectoral fins and pink penises appear through the splashes. Yet, these rare sightings do raise a few questions. Does copulation take place more often at the surface or at depth? Are these sightings the rule or the exception?

The sperm whale is a special case. Males of this species spend several years feeding in the nutrient-rich waters of the North. They then join female sperm whales in the tropics when they feel they have a chance at seduction. So, don't expect to catch these huge animals in the act during their visits to the Estuary!

Similar to the beluga whale, the other species of toothed whales that visit the St. Lawrence mate and give birth in spring and summer. It is not rare to see newborn harbour porpoises swimming alongside their mothers in the Estuary. The female of this species generally gives birth every year… even though its gestation period is from 10 to 11 months! She barely has time to wean one calf before giving birth to its sibling. Another amazing fact concerning this species: male harbour porpoises have enormous testicles that allow them to produce copious quantities of sperm. This is how males of this species compete. The male harbour porpoise that produces the greatest amount of sperm increases its chances of impregnating the female, who mates with several males. The testicles of the male harbour porpoise can have a combined weight of over 2 kg. Not bad for an animal weighing less than 60 kg! A human male with the same «equipment» would have testicles of 3 kg or more.

Although most toothed whales sighted in the St. Lawrence mate and give birth in summer, baleen whales do so in winter. Humpback whales gather in the Caribbean. But why do they head for this sunny destination? Apparently, the most important advantage for gestating females is to give birth in an area where the main predator of their calves, the killer whale, is rarely seen. As for the rest of the female and male humpback whales, what motivates them to also choose this distant location to mate? There are many different hypotheses, none of which are unanimously accepted by all researchers.

Neither have the other whales of the St. Lawrence adopted this way of life. For example, right whales give birth between November and March in the waters off Georgia and Florida. Yet the males, along with the females of this species that are not gestating, do not join the new mothers with their calves. Instead, they remain along the coast of the north-eastern United States. Curiously, right whales can be seen mating year round, not just 12 months before the calving season. Why? Again, no one knows for sure

Rorqual whales (with the exception of the humpback whale) are even more mysterious. The precise area where they gather is not known. Neither have their reproductive strategies been identified. Despite their best efforts, the whalers of yore never discovered their mating grounds. A few clues have led researchers to believe that these whales move southward, far offshore, without truly gathering together. The large rorqual whales likely find each other in the immensity of the ocean by producing low-frequency sounds. They are likely able to hear each other over tens or even hundreds of kilometres. A recent study has put forward the theory that fin whales produce strong and repetitive mating songs. Blue whales, on the other hand, sometimes travel in pairs in summer. According to MICS data, the pairs are often composed of a female blue whale accompanied by a male, with the larger female almost always out in front. These pairs are more abundant near the end of summer.

What proof do we have of the love lives of whales in the St. Lawrence? Female rorqual whales accompanied by calves are rare in the St. Lawrence. Only humpback whales regularly bring their offspring into the Gulf. Minke whales appear to be in the habit of weaning their calves before returning to their feeding grounds. What is rare for blue whales in the St. Lawrence is very common in Iceland. Does this indicate a reproductive problem for the whales of the St. Lawrence or simply a difference in behaviour? Finally, the St. Lawrence is not a nursery for fin whales, although a few female fin whales, like Perroquet and Triangle, choose to return here with their calves.

The study of acoustics, telemetry, photo-identification and genetics give us insights into the love lives of the whales. We already know a lot more than we did fifty years ago, when whales were still being hunted. Yet, we still don't know where Vergetures, U2, El International and Chameau go during win ter, nor… what they do!