A rented minivan with the seats folded down was all that was required to transport the entire DNA history of one of the largest creatures on Earth to its new home 1,700 kilometres away.
Until last week, the scientifically invaluable collection and database of North Atlantic right whale DNA was housed at Trent University in Peterborough, Ont., inside Bradley White’s forensic wildlife DNA lab.
Now that White has retired, an associate professor at Saint Mary’s University in Halifax and his colleagues will oversee the collection.
With the help of guaranteed federal funding of nearly $25,000 per year over the next four years, Tim Fraser’s lab will add to — and maintain — the collection to better understand and more quickly identify the critically endangered whales.
40 tonnes of decomposing flesh and blubber
The importance of being able to identify individuals quickly using DNA instead of manually flipping through a photo archive of right whales became more urgent after at least 18 right whales were found dead in U.S. and Canadian waters in 2017.
Cathy Merriman, a species-at-risk biologist with the Department of Fisheries and Oceans, said right whales were doing well for about 20 years, up to 2010.
“From 2010, they started to decline but it took about six or seven years … to really understand that a decline had happened,” said Merriman.
“Coincidentally, around the same time they realized that it was a decline, that’s when we had this terrible catastrophe in 2017.”
Forty tonnes of decomposing flesh and blubber drifting around the North Atlantic for weeks or months at a time can make identifying the species, let alone an individual, impossible by sight alone.
Scientists usually identify individual right whales in one of two ways:
- Comparing the whale’s unique pattern of callosities — irregular patches of hardened skin on their snout — with an extensive photograph collection.
- Taking a skin sample from the whale to get a DNA match from the database at Fraser’s lab.
What does it take to get a DNA sample from a live, swimming whale? A crossbow, a steady hand and a bit of luck.
“Collecting samples from free-swimming whales is a tricky business,” said Fraser.
“The arrow goes in just a little bit, like maybe about a centimetre, and then it bounces back out and the middle of this arrow has little prongs in it that will catch the skin…. It’s about the size of a pencil eraser and then the arrow will float in the water.”
There are a number of reasons scientists rely on DNA analysis for studying right whales.
The callosities take time to develop, which means identifying calves in later years can be difficult solely based on photographs.
In the past, mothers travelling with calves in the relatively small Bay of Fundy could be tracked and identified.
But since more right whales have been chasing their microscopic prey into the vast Gulf of St. Lawrence, it makes it harder to keep track of the babies before their unique callosities develop.
420 samples collected to date
A DNA sample in the database removes all doubt when it comes to right whale identification.
For Fraser, the roughly 420 samples in the database collected over the last few decades paint a picture of generations and the rate at which inbreeding is happening in the small gene pool.
Right whales’ rate of reproduction is much lower than expected when compared to other whales of its size. Fraser is studying whether inbreeding is contributing to genetic problems and affecting the number of viable offspring.
Fraser also said due to the small number left, North Atlantic right whales have some of the lowest genetic diversity across all whale species.
“And so what we’re trying to do is essentially build the family tree of North Atlantic right whales,” he said.
“See who’s mating with who and see what the genetic characteristics are of the individuals that have high reproductive success versus the individuals that have low reproductive success.”
Right whales are critically endangered, with only about 417 individuals left in the world.
‘Not a good calf year’
Necropsies found many of the whales that died in 2017 had become entangled in fishing gear or were struck by ships, resulting in strict closures of fishing areas and speed limitation on vessels.
No calves were spotted during the 2018 breeding season, so when seven calves were born this year off the coast of Florida and Georgia, it was hailed as good news.
“Although seven is better than zero — the average for the past 30 years is about 17 calves per year,” said Fraser.
“So this year is still not a good calf year at all. And so I’m really trying to understand why is that reproductive rate so much lower than what we know they’re capable of and trying to use genetics to understand that.”
With so few right whales left, and only about 71 breeding females, understanding why right whales are dying in disproportionate numbers could be key to saving the species.
Last week, a right whale was found dead for the first time since the unprecedented mortality event in 2017. A necropsy to determine the cause of death performed over the weekend on New Brunswick’s Miscou Island was inconclusive.
Merriman said the whale’s death was sad, but not shocking.
“It was a difficult thing to hear and also realizing that the necropsy was inconclusive is also difficult because it means we can’t really understand what happened,” she said.
“All we can do is hope that that’s the only incident that will happen like that this year because, like I say, the fishing industry, the shipping industry, Fisheries and Oceans and Transport Canada have all been working really hard to try and prevent more of these incidents.”
Article source: https://www.cbc.ca/news/canada/nova-scotia/north-atlantic-right-whale-dna-database-moving-to-halifax-1.5170360?cmp=rss