How tiny zooplankton could help protect endangered right whales

In a series called Deep Trouble, CBC News explores the perils facing the endangered North Atlantic right whale.

Canadian scientists are developing a tool to predict the location of North Atlantic right whales in the Gulf of St. Lawrence based on the movement of their prey, tiny zooplankton known as calanus.

The computer modelling could help address one of the biggest challenges in protecting the critically endangered mammals, said Quebec-based federal Fisheries and Oceans Canada scientist Stéphane Plourde.

"There are so few of them and the area is so large compared to their previously visited areas," he said.

There are only about 400 right whales left in the world.

In the last decade, right whales have been drawn to the gulf each spring in search of food.

But depending on the year, almost anywhere in the gulf could be a suitable place for a meal, said Plourde.

"The main challenge will be to determine where it will be most advantageous for the right whale," he said. "It's a very large area."

Research indicates the shallower waters in the southern gulf — bordering Gaspé, Que., New Brunswick, Prince Edward Island and Nova Scotia — offer the best prospect for the energy-rich copepod species of zooplankton known as calanus.

The southern gulf attracts zooplankton carried in on currents from elsewhere in the gulf.

Plourde and other researchers are focused on biological, chemical and physical conditions in those areas.

Model will be ready within 5 years

"What's going on in late winter and spring is key to understanding where in the southern gulf zooplankton will be greatest during the spring and early summer," he said.

"This is a key, key area to study."

Plourde said the model is not yet operational, but will be in under five years.

It's believed right whales began moving into the gulf several years before the crisis year of 2017 when 12 died in the area.

After shipping and fishing restrictions were imposed, no right whales died in 2018 in the gulf.

Unclear where recent ship strikes occurred

The measures were still in place in 2019 when six died, two from ship strikes. All were found in the southern gulf.

Fisheries and Oceans Canada said it cannot confirm the locations where the right whales were struck given that dead whales can float for some time before being found.

"It is difficult to determine if the right whales were struck in areas with an abundance of energy rich copepods," said spokesperson Benoit Mayrand in a statement to CBC News.

Three entangled right whales were spotted in the gulf recently.

On Thursday, a rescue team in New Brunswick partially free one of the whales.

Why right whales are moving from traditional habitats

A reduced abundance of zooplankton due to warming temperatures is suspected as one reason why fewer right whales are being seen in their traditional spring and summer habitats off Grand Manan Island, N.B., and in the Roseway Basin, off southern Nova Scotia.

Recently published Fisheries and Oceans Canada research says zooplankton in the gulf are also being affected by warming temperatures at mid and lower depths, adding yet another complication.

The largest and most energy-rich copepods have been declining in portions of the southern gulf.

The implications are also under investigation by Fisheries and Oceans Canada.