What is killing whales in Gulf of St. Lawrence?
Marine biologists to perform necropsy in bid to shed light on mysterious deaths
A necropsy — or animal autopsy — was being conducted Thursday on one of six endangered right whales that have died this month in the triangle between Quebec’s Îlesde-la-Madeleine, Miscou Island in New Brunswick and the northern tip of Prince Edward Island.
A team of marine biologists and rescue workers successfully towed one of the carcasses of North Atlantic right whales to shore in Norway, P.E.I., on Wednesday afternoon so they could finally begin to examine it and shed light on the mysterious deaths of these gentle giants in the Gulf of St. Lawrence.
Until the necropsy is completed, which may take several days, biologists can only speculate as to the causes, natural or man-made.
Here are four things to know about the whales and the monumental operation undertaken to find out what happened.
Tonya Wimmer, the director of the Marine Animal Response Society and a marine biologist at Dalhousie University, says her team is going through sequences of aerial photographs taken of the carcasses as they float around the Gulf of St. Lawrence to keep track of their location — and make sure there are no more than six. Three of them have been fitted with GPS trackers to make it easier to locate the carcasses as they drift. But the hardest part is getting at least two of them ashore, using a vessel from Fisheries and Oceans Canada to tow them, then with help from a local P.E.I. contractor to haul the bodies onto the shore.
The whales are on average 13 to 16 metres long and weigh 40,000 to 70,000 kilograms.
“It’s no easy task,” Wimmer said. “But this is the first step into hopefully getting clarity on what happened — to look at them very carefully, inside and out.”
By sundown Wednesday, the team had successfully hauled a male right whale onto shore. It was the second of the six whales discovered dead this month.
Also involved in the operation are the Canadian Coast Guard, Canadian Wildlife Health Cooperative-Atlantic Veterinary College/ UPEI, Université de Montréal, Urgences Mammifères Marins and the province of British Columbia.
There are an estimated 500 North Atlantic right whales living today. While once much more abundant, centuries of whaling for whale oil, blubber and baleen reduced the population to fewer than 100 individuals by 1935. It was called the “right” whale because it was the right whale to chase — it moved slowly and when it died, it floated conveniently on the surface.
A global ban on hunting the whales was established in 1935, but more modern threats, principally collisions with ships and entanglement with fishing equipment, have kept the population low. Meanwhile, the number of births has fluctuated greatly. In 2009, according to reports in the U.S., a record 39 new calves were sighted. In 2012, however, there were only seven sighted. The six recent deaths represent a loss to the population of more than one per cent.
According to Fisheries and Oceans Canada, collisions with ships in the heavy traffic area of the Eastern Seaboard accounted for 37 per cent of deaths of North Atlantic right whales between 1970 and 2006. The second most common cause of death was entanglement with fishing equipment, which killed at least eight whales in that time frame.
One of these two causes may prove to be the culprit here. But there are no strong external clues pointing to what may have happened, and Wimmer suggested another theory: the whales may have died as a result of a toxic algae bloom in the Gulf of St. Lawrence.
“We’re not sure what happened,” Wimmer said. “There are a lot of hypotheses on the causes of death — all the theories are on the table.”
Right whales are also known to be affected by noise and climate change, as well as fluctuations in the amount of zooplankton available.
Three right whales were found dead in the same general area in 2013, Wimmer said. Back then, one of the whales was brought to shore for a necropsy, but it proved inconclusive. The other two whales were lost at sea.