St. Lawrence beluga researchers point to 'worrisome' deaths of mothers, newborns

Canadian marinemammal researchers are sounding the alarmabout beluga deaths in the St. Lawrence Estuary,after a majority of thecarcasses recovered last year wereonce again found to belong to pregnant females, new mothers and newborn calves.

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The figures, provided by Fisheries and Oceans Canada to Radio-Canada, are part of a "worrisome" trend, said federal research scientistVronique Lesage.

Of the 14 carcasses recovered in 2015, six were newborn calvesandthree were pregnant.

In 2014, 11 beluga carcasses were recovered, and six of them were babies.In 2013, 17 deadbelugas were found, and four ofthem were babies.

Necropsy findings arecause for concern

Post-mortem investigationsconducted atthe University ofMontreal'sfaculty of veterinary medicine inSt-Hyacinthehave shown that the deceased adult females were either just about to give birth or had just given birth.

One female beluga found on a riverbank in 2015 had a ruptured uterus.

Carcasses of newborn belugas, meanwhile, showed no signs of injury, infection or tumours, suggesting to researchers that they died of starvation or dehydration because they had been separated from their mothers.

Since 1983, all belugasfound dead in Quebec have undergone necropsies (post-mortem investigations)at the St-Hyacintheveterinary centre.

For the first 25 years of that program, in any given year, there were never more than three beluga calves found dead and sent for autopsies.

However, in seven of the past eight years, three or morecalves are known to have died annually.

StphaneLair, a veterinary professor inSt-Hyacinthe, called the situationan "epidemic."

These deaths are "very unusual for a wild animal," he said.

Population in jeopardy

Robert Michaud, thescientific director of Quebec's Marine Mammals Research and Education Group,said the number of belugas in the St. Lawrence has been in decline since the early 2000s, with a drop of 1.0 to 1.5 per cent per year.

He said the declineisapproaching a crisis level.

"The potential of the population to recover is disappearing with these deaths," Michaudsaid.

There are currently an estimated900 belugas in the St.Lawrence Estuary, according toFisheries and Oceans Canada.

Fifteen years ago, there were at least 1,000 belugas, and a century agothere were 10,000.

Following a ban on beluga hunting in the 1970s, their numbers should have increased, but the opposite happened.

Possible causes

Researchers have come up with four main hypotheses to explain the decline of the beluga whale, including:

• Contaminants in the water such aspolybrominated diphenyl ethers(PDBEs), which were banned more than a decade ago but remain present in the environment.
• The decline in the number of herring in the St. Lawrence Estuary, a valuable source of food for beluga mothers and their young.
• The absence ofice cover due to rising water temperatures. The iceserves as protection against wind, waves and storms.
• The rise in marine traffic, which can be disruptive, particularly to female belugas and their calveswho use sound to communicate.