As southern resident killer whales dwindle, more food options mean northern population is thriving

The most recent count of the northern resident group of orcas reported 309 whales, more than four times the number of southern residents.

Researchers say food is more available for northern residents

Researchers attribute the strength of the northern resident killer whale population to more available food sources. (Dave Ellifrit/Centre for Whale Research)

As concern grows over the decline of the southern resident killer whale population following the presumed death of the young female J50, the story off B.C.'s north and central coast is much different. 

The most recent count of the northern resident group of orcas reported 309 whales, more than four times the number of southern residents.

"The northern killer whale population is doing much better… [and] doesn't seem to be going through the same slow decline," said Lance Barrett-Lenard, head of the cetacean research program at the Vancouver Aquarium.

Both populations feed on chinook salmon as their primary prey but Barrett-Lenard said the northern whales have less competition and more options to choose from, with fish returning to the Skeena River, Nass River and Owikeno Lake.

More options for food

"If one system is bad… our northern residents have the opportunity to shift their focus to fish returning to another system," Barrett-Lenard told Daybreak North host Carolina de Ryk.

"In the case of the southern residents, however, that population is really dependent on chinook bound for the Fraser River and to some extent the Columbia [River] … When those systems are down it doesn't have anywhere to go."

He said with stocks of chinook declining across the province, northern residents could very well face the same fate. He noted their population growth has begun to taper off after keeping a steady rate for the past 30 years.

Another possibility his colleagues have considered is that the northern whales might take over the southern residents' territory if the latter were to die out.

Maintaining marine diversity

Barrett-Lenard said the disappearance of the southern residents would be a huge loss of cultural significance for the province.

"As people, we value diversity. We value the diversity of Indigenous groups, we have words like cultural genocide, we're very concerned if a language is lost. In the same way I think we recognize that these killer whale populations are ancient, unique, distinct cultures," he said.

"If one of them goes, it will eventually be replaced in space by another one — but once it's gone, it's gone forever. We as humans have made this value judgment that we don't want that to happen."

To protect and sustain the northern resident killer whales, Barrett-Lenard said people must me mindful of the factors that have caused the decline of their primary food source.

"Certainly, climate change is important; preserving those estuarine​ and river spawning habitats is incredibly important; and keeping our own monitoring and management of our fisheries is important," he said.

To hear the full interview, click on the media below:

The presumed death of killer whale calf J50 is raising concerns about B.C.'s residential orca population as numbers decline on the south coast, but the story on the north coast is much different, with the Northern resident pod population last reported at 309 whales. 8:52

With files from Daybreak North

Read more from CBC British Columbia

Comments

To encourage thoughtful and respectful conversations, first and last names will appear with each submission to CBC/Radio-Canada's online communities (except in children and youth-oriented communities). Pseudonyms will no longer be permitted.

By submitting a comment, you accept that CBC has the right to reproduce and publish that comment in whole or in part, in any manner CBC chooses. Please note that CBC does not endorse the opinions expressed in comments. Comments on this story are moderated according to our Submission Guidelines. Comments are welcome while open. We reserve the right to close comments at any time.