A mandatory slowdown of ships in the Gulf of St. Lawrence is the right move for protecting the endangered North Atlantic right whale, says a scientist who has studied the whales for decades.

After a spate of whale deaths in Canadian waters this summer, the federal government asked vessels 20 metres or longer to reduce their speed to 10 knots in the western part of the gulf where the animals have been vulnerable.

"A speed reduction will help reduce the risk of vessel strikes," said Moira Brown, senior scientist with the New England Aquarium and the Canadian Whale Institute.

Whale necropsy

Veterinarians helped perform a necropsy on a right whale brought ashore on Prince Edward Island in June. (Nicolas Steinbach/Radio-Canada)

But the lower speed will also reduce the severity of the impact, increasing the chances a whale will survive a ship collision.

When a whale is struck by a vessel going 20 knot, the likelihood it will die is 100 per cent, according to research done by scientists at Dalhousie University in Halifax, Brown said.

"If they reduce that to 12 knots, the likelihood drops to 50 per cent," she said. "And reducing it to 10 knots, the likelihood of a whale being killed by a ship is down to 30 per cent."

Right whale freed

This whale suffered injuries that rescue officials believe came from being entangled in fishing gear. (Canadian Whale Institute/Anderson Cabot Center for Ocean Life)

Two of the 10 whales that died this summer suffered trauma from ship collisions, and another showed evidence of entanglement in fishing gear. Necropsy results have not been completed in all cases, although collisions or entanglement are  the suspected causes of death.

Brown said she understands the burden to the shipping industry, but the lower speed limit, in effect until the whales leave the area later this year, is necessary to save the 500 or so North Atlantic right whales that remain.

North Atlantic right whales are baleen whales and, unlike toothed whales, are not able to echo-locate, or use sound waves to determine where objects are, Brown said.

Aerial and boat-based North Atlantic right whale sightings, Gulf of St. Lawrence

Fisheries and Oceans Canada and the National Oceanic and Atmospheric Administration in the U.S. have logged more than 335 hours conducting aerial surveillance in the Gulf of St. Lawrence to track the migration of the North Atlantic right whales, Fisheries Minister Dominic LeBlanc has said. (Government of Canada)

"For example, when you see a dolphin in front of a ship, they know exactly where that ship is, they can eco-locate," she said.

The mandatory slowdown replaced a voluntary one the government asked for last month.

Brown said there are plenty of ways for speed to be monitored to make sure ships obey the slowdown order.

"All of these ships transmit over VHF frequency, they transmit a signal called an 'automatic identification signal,'" she said, adding it was put in place by the International Maritime Organization, a United Agency agency, to reduce ship collisions.

Right whale

A dead right whale was found on the west coast of Newfoundland. (Fisheries and Oceans Canada)

Those signals can also be monitored from land and by satellite. 

Vessels that don't comply with the mandatory slowdown can be fined between $6,000 and $25,000.

'Difficult not to respond'

After the death of whale rescuer Joe Howlett, the federal government suspended efforts to disentangle North Atlantic right whales from fishing ropes.

Since the suspension began, no right whales have been reported entangled, Brown said.

"It will concern me a whole lot when we get the first report of an entangled whale," she said.

"Right now, we don't have any reports of entangled right whales, but once we do, it's going to be very difficult not to be able to respond."

With files from Information Morning Saint John