Four B.C. whale deaths in a week baffle scientists
By Bethany Lindsay
The discovery of four dead humpback whales in B.C. waters in a single week, just as Alaska is experiencing a surge of whale deaths, has scientists searching for a possible connection.
In the last few days, Canadian marine mammal experts have travelled north to Klemtu and Haida Gwaii to perform necropsies on two humpback carcasses, while another two dead whales have been spotted floating in Hecate Strait and off the west coast of Vancouver Island.
Meanwhile, 21 humpback and fin whales have been found dead in southeast Alaska during the past month, according to Paul Cottrell, Pacific marine mammal coordinator for Fisheries and Oceans Canada.
“It’s definitely a pulse of deaths and something that we’re going to keep our eye on,” Cottrell said.
No cause has been pinpointed for any of the deaths so far, and results from this week’s two necropsies in B.C. will take weeks to come back. Once they arrive, officials will share what they’ve learned with their counterparts in the U.S.
“These samples are very important to look at what may have caused the death of these animals, to see if there’s any relationship — whether there’s a pathogen that may be causing this,” Cottrell said.
The dead whale near Klemtu was first reported a few days ago when the carcass was still bobbing out in the water. A group of First Nations guardians tracked down the floating animal and towed it to shore so a necropsy could be performed.
Cottrell and veterinary pathologist Stephen Raverty have both examined the female whale, estimated to be more than nine metres in length.
Media reports have suggested it died after becoming entangled in fishing gear, but Cottrell said it is far too early to come to that conclusion.
“It’s an interesting one because there are scars on the tail stock that indicate there was at one time an entanglement, but the tissue’s fairly necrotized. The indications are that it may have been a prior entanglement,” he said.
The scientists also noticed wounds on the whale’s body. Samples of its organs, tissues and fluids have been sent for analysis to help narrow down the cause of death.
The whale that washed ashore in Haida Gwaii was a smaller female, measuring 7.5 metres long. Cottrell said there was no obvious cause of death.
In both cases, the carcasses were quite fresh, making it much easier to obtain accurate results from the necropsies. Cottrell said it’s absolutely crucial for members of the public to call the B.C. Marine Mammal Response Network at 1-800-465-4336 as soon as they see a dead or injured whale.
“The general public, they’re our eyes and ears out there,” he said. “The quicker we get these calls, the better.”
He’s hopeful that fisheries officials will be able to track down the two carcasses that are still floating out at sea so necropsies can be performed on those as well. Most, if not all, of the dead whales in Alaska have been spotted in the open ocean, so scientists there have a limited number of tissue samples to work with.
B.C.’s humpback whales have enjoyed a remarkable turnaround in recent decades, but Cottrell said if the current deaths signal a serious threat to their recovery, scientists need to be aware.
“They’re still a species of concern, so especially if there’s anthropogenic or human-caused things affecting the recovery, those are things that we want to know about,” he said.
Photo Credit: Christopher Michel via Flickr