Pregnancy tests for the St. Lawrence's Beluga Whales!

Belugas surfacing. Photo credit: Véronique Lesage, DFO

Belugas surfacing. Photo credit: Véronique Lesage, DFO

It is late summer, 2013. On the ship's deck, Véronique Lesage, researcher at the Maurice Lamontagne Institute in Mont-Joli, scans the rough waters of the St. Lawrence Estuary. Between sky and sea, she can make out white dots bobbing with the rhythm of the swell: Beluga Whales. Finally—the sampling campaign can begin.

Despite difficult weather conditions, the Fisheries and Oceans Canada research scientist and her team will successfully take skin and blubber samples from about twenty of these iconic river inhabitants over the course of three weeks. Their main goal? "To determine, based on these samples, if the proportion of pregnant female Belugas is comparable to that of a healthy Beluga Whale population. That means a third of adult females, normally," says Véronique Lesage.  An unusual pregnancy test, to say the least.

This project, which is part of the recovery plan being implemented for the St. Lawrence Beluga Whale, will take place over four years, three of which will involve random sampling to gather meaningful data. When the project is completed in 2016, the results will help us better understand why the St. Lawrence Beluga population is so fragile. From 2007 to fall 2013, the estimated number of Belugas dropped from about 1100 individuals to just 890.

A tailor-made pregnancy test

In 2007, during a review of the St. Lawrence Beluga's status, Fisheries and Oceans Canada scientists hypothesized that low recruitment (number of births, number of young that reach sexual maturity) could explain the drop in population. But was the problem the survival of Beluga young, or a low reproductive rate for females?

Thanks to her project, Véronique Lesage will be able to verify whether female St. Lawrence Belugas have a pregnancy rate in the normal range, which is 33% since the species reproduces once every three years. This means the researchers must be able to determine whether females are pregnant. "Progesterone, a hormone secreted in large amounts by pregnant females, will allow us to accurately determine the pregnancy rate. Beluga blubber samples will be tested for hormone levels at Fisheries and Oceans Canada's Maurice Lamontagne Institute in Mont-Joli," Lesage explained.

This unusual idea came to the researcher in 2002, after a similar study was conducted for the Minke Whale. After developing and validating the method for measuring progesterone in fat with deceased animals (pregnant or otherwise), Lesage refined it with help from colleagues at the National Oceanic and Atmospheric Administration in La Jolla, California.

Sampling 101

Cross-section of a Beluga biopsy. Photo credit: © GREMM

Cross-section of a Beluga biopsy. Photo credit: © GREMM

Over the course of the three-year sampling campaign, during three weeks each year in late September, Lesage plans to take random tissue samples (skin and blubber) from no less than 30 to 40 individuals per year. Such a feat is necessary in order to get a representative sample of female Belugas because, in the water, it is sometimes difficult to tell young males and females apart. Only subsequent analysis of DNA from a skin sample, taken at the same time as the blubber sample, can confirm the whale's sex.

And sampling in the wild is quite a challenge. Forget any parallels with human beings or notions of capturing Belugas to take blood samples. With the lab far away, a certain amount of ingenuity is required.

In this case, samples are taken using a modified firearm. Instead of bullets, it fires darts that can retrieve a small sample of skin and of the external layer of blubber. Developed by Robert Michaud of the Group for Research and Education on Marine Mammals (GREMM), this technique allows a biopsy to be taken from a Beluga at a distance, from the deck of a vessel.

Beyond pregnancy tests

Belugas. Photo credit: © GREMM

Belugas. Photo credit: © GREMM

Once the sample—which is 2.5 cm long (including the skin) and 6 mm in diameter—is recovered, the project's geneticists can start with genetic analysis of the skin. Their goal is to confirm the individual's sex and, for females, measure the progesterone in the blubber. But that's not all.

"Despite the small amount of tissue collected, we can also investigate the genetic diversity of the species by measuring testosterone amounts for male individuals to see if they've reached sexual maturity. Also, if we measure stress hormones, we can see whether St. Lawrence Belugas are exposed to a level of stress comparable to that of populations farther north, where there is less human activity," says Lesage.

This is a big job, and she isn't doing it alone. Her team includes Robert Michaud of GREMM, who has extensive knowledge of the Estuary's Belugas; Tim Frasier of Saint Mary's University in Nova Scotia, a geneticist specializing in that population's social structure; and Greg O'Corry-Crowe of the Harbor Branch Oceanographic Institute in Florida, a genomics expert and specialist in the Arctic Beluga.

If a normal reproductive rate is observed when this major project is completed, meaning one in three female Belugas is pregnant, more questions will have to be asked to explain the decline of the St. Lawrence Beluga population. Specifically, according to Véronique Lesage: "Are the females bringing their pregnancies to term? If so, are their young surviving?"

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