'Unprecedented' absence of southern resident killer whales from Salish Sea concerns researchers

Victoria -

The most common pod of southern resident killer whales who migrate to the Salish Sea during the summer have not been seen for than 100 days, marking a highly unusual absence from their historic summer hunting ground, according to researchers.

Monika Wieland Shields, director of the Orca Behavior Institute in Washington state, says the absence is "unprecedented," and likely does not bode well for the state of the salmon ecosystem near B.C.'s Fraser River.

"April through September is typically the peak season for the southern residents here in the Salish Sea," said Shields.

"J-pod is sort of the most resident of the three pods, but K-pod and L-pod we would expect to see on a near daily basis in and around the San Juan islands, off Victoria, off Vancouver all summer long."

She says the last confirmed sighting of a J-pod southern resident killer whale in the Salish Sea was on April 10.

"So for us to go 100 days this time of year is unprecedented," said Shields. "I think it's really telling us there's not food for them there."

The last sighting of any southern resident killer whale in the Salish Sea was on July 1, when members of K-pod were seen in the area, according to Shields.

DECLINING CHINOOK SALMON POPULATIONS

Historically, southern resident killer whales would follow migrating chinook salmon into the Fraser River during the spring and summer months, according to Shields.

But a decline in chinook salmon in the area means the orcas are likely turning elsewhere to find food.

Shields says that all three pods have been spotted near Swiftsure Bank off the southwest end of Vancouver Island this summer. The researcher believes it's because the orcas can find a wider range of fish migrating to other parts of the ocean, rather than relying on chinook salmon from the Fraser River.

"If the Fraser River is not enough to sustain them, by being on the outer coast they can feed on salmon from a wider geographic area," she said.

"Maybe their new travel patterns are actually working for them and they're finding more food elsewhere," Shields said. "But it's a pretty dramatic shift for them to completely abandon this area that was considered their core summer habitat for decades, and probably going back hundreds, even thousands of years."

Shields says that if southern resident killer whales have abandoned the Fraser River area during the summer, other species that rely on chinook salmon may be suffering too.

"It's a concern for the whole ecosystem and all the other species that depend on the Fraser River chinook salmon as well," she said.

Erin Gless with the Pacific Whale Watch Association agrees that a lack of prey is having a noticeable impact on the orcas.

Fewer salmon are returning to the area each year, and the average size of each salmon is declining, she said.

Gless says it "takes the same amount of energy to catch a fish," but now the salmon that the orcas are feeding on may be half the size of what they were historically.

LOOKING FORWARD

Back in Friday Harbor, Shields says there's no simple solution to rebuilding the food chain.

"If it were easy to recover wild salmon we would have done it by now," she said.

Shields says that a closer look at commercial fishing management along the West Coast could help.

"Fish farms in British Columbia are also a big concern," said the Washington resident.

She says that B.C. fish farms are likely impacting wild salmon, with many operations being located along migration routes for wild fish and that they can spread diseases to wild salmon.

The researcher says she supports the federal government's controversial decision to phase out fish farms in the Discovery Islands region of B.C.

"There are plenty of issues on both side of the border that are affecting the whales," said Shields.

Sue Grant, head of the State of the Salmon Program for Fisheries and Oceans Canada, adds that climate change is contributing to the decline of chinook salmon across North America.

Ocean temperatures are warming, affecting fish, and heat waves, like the record-setting heat dome seen in B.C. this summer, also affect the temperatures of rivers.

The increasing scope of forest fires also impacts water sheds, says Grant. The loss of tree canopy leads to more sediment in water systems and decreases overall water quality.

The Center for Whale Research estimates that there are roughly 74 southern resident killer whales left in the wild.