They are among the world’s largest creatures, but the planet’s 400 remaining North Atlantic right whales are remarkably elusive.
Though adult members of this critically endangered species can be as long as a city bus, their movements remain difficult to track, despite the best efforts of scientists struggling to deal with a rapidly rising death toll off Canada’s east coast.
“It is kind of mind-boggling that we can lose track of these large animals,” says Boris Worm, a biology professor and well-known whale expert at Dalhousie University in Halifax.
“But the ocean is a very large place, and they only spend part of their time at the surface – and they move around quickly, if they want to.”
Though these whales typically travel north to feed in Canadian waters in June, some have been known to stick around most of the year – a recently discovered trait – and one male was spotted off the coast of France a few weeks ago.
The same whale swam to Iceland last year.
More importantly, a significant number of right whales have changed their migration patterns since 2014-15.
Instead of heading to their traditional summer foraging grounds in the Bay of Fundy and the Roseway Basin off southwestern Nova Scotia, the population has shifted to a more northerly destination – right into the busy shipping lanes of the southern Gulf of St. Lawrence.
Since early June, eight right whales have died in Canadian waters, the worst death toll since 2017 when there were 12 confirmed deaths in Canadian waters and five in the United States.
Tests have revealed that at least three of the whales that died this year were probably killed by collisions with ships.
“It’s so critical to know where they are to keep them safe,” Worm said in an interview Tuesday.
“We’re trying all the approaches in the scientific toolbox. Any traces they leave, we’re trying to pick them up.”
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Some of Worm’s colleagues are developing a predictive model that could help fisheries officials determine where the whales are most likely to go as they search for their favourite food: copepods.
Hansen Johnson, a PhD candidate at the university’s Oceanography Department, said his lab’s research is focused on finding the locations where these flea-sized creatures congregate.
“If we can predict where and when there’s going to be good feeding sources – and these copepods show up in large numbers – we can more accurately predict when and where right whales will show up and address the risks,” Johnson said in an interview.
For almost three weeks, a team of six scientists has been conducting research aboard a chartered crab fishing boat in the southern Gulf of St. Lawrence, using nets and electronic gear to find copepods, which look like tiny, translucent shrimp.
“It’s unclear at this stage how precise our model could be, but we know that this approach of following the food works,” Johnson said.
When Dalhousie researchers looked at the currents and the structure of the ocean floor in the places where right whales were known to forage for zooplankton, including the Roseway Basin, they determined a pattern that also appears in portions of the Gulf of St. Lawrence.
When surveillance aircraft were dispatched to search those areas in 2016, they hit the jackpot.
“On the first flight, they found 40 right whales and this habitat was discovered,” Johnson said, though he stressed that some right whales may have been frequenting these basins for a long time.
“They’re like cereal bowls where these food resources collect,” he said, noting that the latest research in the gulf is based on work by renowned Canadian oceanographer Kimberley Davies.
“The currents are right. The ocean bottom structure is there.”
On another scientific front, Worm is working with a student to develop an automated satellite tracking system that will eventually spot the whales from space and report their positions.
Though the satellite imagery is incredibly detailed, the existing computer algorithms are unable to distinguish between species, and spotting the whales becomes difficult when the ocean is rough.
When the water is turbulent, it’s often difficult to distinguish between a surfacing whale and a partially submerged rock – or even a small boat.
“We haven’t cracked that nut yet,” Worm said.