HAIDA GWAII, B.C. - A fifth grey whale has been found dead on British Columbia's coast in what one research biologist says could be a trend towards of record-setting deaths even as the species does “well” overall.
John Calambokidis of the Cascadia Research Collective based in Olympia, Wash., said Tuesday that 23 grey whales have been found dead this year in his state, and the dead greys are all found along the same migratory route. He said he isn't involved in studying the whales found dead in Canada.
Those deaths bring the total number of carcasses found along the migration route from California to Alaska up to 70, according to figures from the U.S. National Oceanic and Atmospheric Administration, or NOAA.
Calambokidis said the last such major mortality event for grey whales was in 1999 and 2000.
“We actually seem to be at a pace that is ahead of even those two years, as in, if we keep getting strandings we'll surpass those years.”
The Department of Fisheries and Oceans described the discovery of the fifth dead whale May 16 on Haida Gwaii as part of an “upward trend” from recent years, in an email.
“Fisheries and Oceans Canada is working closely with NOAA to determine if the grey whale deaths in the U.S. are connected,” the federal department said in an email.
Three of the whales have been found on Haida Gwaii, one was on Vancouver Island's west coast and another near Victoria. Necropsies are being conducted on all but one that was too decomposed but results are not yet available, the department said.
The department's marine mammal co-ordinator Paul Cottrell was en route Tuesday to Haida Gwaii to study the most recent whale found and a necropsy would be performed with the help of a provincial veterinarian.
Most grey whales in the eastern North Pacific feed in Alaskan waters every year, then fast while they migrate south to Mexico to breed and return, Calambokidis said.
The vast majority of the dead whales that Cascadia Research has studied have been extremely emaciated, he said.
“They have very, very poor nutritional conditions, they have very little oil in their blubber layer,” he said. “We take that as an indication that these are animals that were not able to get enough to eat last year, so it was unable to sustain them through this normal fast period.”
But he said the deaths could actually be a sign of good news. After historic whaling depleted the numbers to an estimated low of a few thousand in the early 1900s, the species has rebounded to more than 20,000 today. It could mean there are so many whales now that the food web is reaching its carrying capacity for the species, he said.
“Grey whales have been increasing in numbers. Even the 1999 and 2000 event was thought to be part of ... grey whales now more fully recovering from commercial whaling and starting to reach some of the limits of the food supply, which is normally thought to keep populations at certain levels,” he said.
Eastern North Pacific grey whales were listed as species of special concern under the federal Species at Risk Act in 2005.
While commercial whaling no longer threatens them, human activities continue to affect grey whales and their habitats, Fisheries and Oceans Canada says on its website.
Salt extraction, oil exploration, offshore mining, toxic spills and industrial noise in shallow marine areas can cause loss and deterioration of breeding and feeding habitats and potentially could affect migration routes. Collisions with ships and entanglement in fishing gear can also kill whales and prolonged ice cover on the arctic feeding grounds limits the feeding season, it says.
Calambokidis said changes to the Arctic ecosystem could also play a role in this year's mortalities.
“We know huge changes have occurred in ice cover in the Arctic. Are any factors like that playing a role? Largely I would view that as too soon to tell,” he said.
