In the waters off the coast of Vancouver Island, a new threat looms for Southern Resident killer whales.
The cetacean morbillivirus, a virus commonly found in mammals in Atlantic waters that has now been detected in some species off the Pacific coast.
“As the climate changes and as the environment in the ocean changes, we’re seeing diseases move into areas that they hadn’t previously been in,” said Michael Weiss, a biologist at the Center for Whale Research on San Juan Island.
Most concerning for the already endangered Southern Resident killer whales, Weiss added, is that the morbillivirus has been found in Pacific white-sided dolphins, a species they commonly interact with.
“Cetacean morbillivirus, in particular, seem to have a really remarkable ability to jump species, really, with very few barriers,” he explained. The virus is “really good at going from one species of whale, to another species of whale, to dolphins.”
The disease is spread through water droplets; similar to the way COVID-19 is transmitted.
“Even folks who haven’t seen whales will know that they create a blow when they surface,” said Anna Hall, a marine mammal zoologist. “And that has some seawater in it, but of course, it also has their breath. And that could be the mechanism of transfer between individuals.”
However, orcas can’t take the same steps humans take to stop the spread of the virus. They can’t wear masks and they aren’t very good at maintaining their physical distance, as they travel in very close and synchronized formations in their pods.
“They move in kind of the same pattern. This means they’re breathing at the same time, so you have two whales coming up very close to each other and breathing one right after another,” said Weiss, noting a moment like that is the opportune time for the virus to be transmitted.
If one Southern Resident killer whale gets infected, 90 per cent of the population is likely to become sick as well.
It would be difficult to save the 73 orcas if they got the cetacean morbillivirus, even with a vaccine. More than half of the population would need to be vaccinated, which, Weiss noted, is difficult to do at sea.
The concern among biologists is that the Southern Resident orcas could die out entirely from the virus.
“If Southern Resident killer whales died out, there are no others on the planet that are like them,” said Hall. “There are other killer whales but there are no other J, K, or L pod that’s out there.”
The best way to protect orcas is to make sure they have enough food to keep them healthy, Weiss added, by implementing policies that maximize the amount of Chinook salmon getting to the Southern Resident killer whales.
“It won’t prevent an outbreak from happening. It wouldn’t prevent it from getting into the population,” he said. “But it might help them deal with it once it’s there. It might lower the mortality rate, might lower the transmission rate.”