New study shows accelerating decline in Southern Resident orca population

Scientists across several areas of marine conservation and animal welfare have released a new study this month on the current state of Southern Resident killer whales (SRKW) that live in Island waters—and the results are more dire than once thought.

SRKW have been listed as a species at risk in Canada since 2005. Currently, only 74 SRKW exist and, according to the study, their population will continue to decline by one whale per year for the next generation. After that, the decline will accelerate rapidly toward extinction.

The study highlights the idea of dark vs bright extinction—dark extinction happens with little awareness or public knowledge, with an animal's population declining out of sight from researchers. Bright extinction, what SRKW are experiencing, happens with full awareness. Scientists know the exact number of living SRKW and why they’re at risk, yet, their decline continues.

“We know what the problem is, but the management actions and mitigation measures are not enough, they're too slow,” said Rob Williams, lead author of the study and co-founder of Oceans Initiative in Seattle. Williams grew up in the Comox Valley and has long been fascinated with the Salish Sea's orca populations.

He says to prevent another case of a bright extinction, several areas of marine and conservation science will need to come together to save these mammals.

Several areas of risk for SRKW

A combination of factors is at play: In the 1960s and 1970s, the population took a major hit with increased live captures for aquarium displays. SRKW were never able to bounce back from this as other threats began to increase. Overfishing of Chinook salmon, SRKW food of choice, has essentially caused a famine for SRKW. The lack of salmon has increased calf mortality rates, with mothers unable to produce enough nutritious milk for their young.

Ocean noise also affects their ability to communicate and hunt, making it more difficult to catch the remaining Chinook—in addition to the dangers of vessel strikes.

On top of that, there are several ocean contaminants—with one known as polychlorinated biphenyl (PCB), a chemical linked to industrial production, causing the bulk of the damage. The excessive level of PCBs in SRKW makes them one of the most contaminated marine mammals in the world, according to the study.

“We phased [PCBs] out decades ago, but they are persistent things,” said Williams. "They stick around. And I don't know how we mitigate those. I think that means since they're so difficult to mitigate, we just have to work even harder on the salmon issues.”

There may be more contaminants at play—as ocean temperatures rise, toxins from algae blooms have been known to make animals sick, and high levels of bacteria have been found in orcas—but for now, scientists don’t have the luxury of figuring out every factor contributing to their decline. Williams says the current approach is almost that of triage in medicine—they just have to “stop the bleeding” and work with the information available.

Williams said that SRKW need a combination of conservation and animal welfare support, an unusual approach from a conservation perspective. Normally, individual animal needs are not paramount to conserving a population. But when only 74 animals exist in one population, each individual is crucial to their survival.

“Having one more [whale] means your population at this size has grown one and a half per cent a year,” said Williams. “That's how small it is.”

Veterinary care could be key

One innovative aspect of this is the inclusion of veterinary science to care for each whale, an emerging aspect of orca conservation.

Veterinarians and wildlife disease experts found that one in five SRKW deaths over the last 40 years were preventable, had they been able to monitor the health of individual orcas, Williams said.

He points to the example of the rescue of Springer—a Northern Resident killer whale that was found alone and emaciated as a calf in the Puget Sound—for a guide to holistic orca conservation. Interventions from conservation groups and veterinary teams in Canada and the US, allowed Springer to be reintegrated with her pod, making her the only orca successfully reintegrated into the wild after being temporarily held in a captivity for monitoring.

A key part of her rescue was veterinary care, where blood and scat samples were taken to confirm she didn’t have any diseases that could put the population at risk.

While Williams says humans shouldn't interfere too much in caring for the whales, being able to monitor each animal with noninvasive procedures like breath and scat samples could help conservation scientists intervene before losing a Southern Resident to something treatable like an infection.

“If we could do that in the ’90s, you can imagine how much further the tools have come with quick lab techniques,” said Williams.

Hope remains in saving the population

Other key changes like reducing ship speed in waters where orcas hunt have had a major impact. Slower ships mean quieter waters, which have been shown to improve orca hunting skills. Though it doesn’t address the issue of dwindling Chinook numbers, Williams says it’s a "Band-Aid solution" to improve how much orcas can catch.

Another promising fix could be the removal of dams in key salmon-run areas. After the dam was removed from Washington state’s Elwha River in 2010, Chinook came back years earlier than expected. Williams says this same bold action is being considered for the Snake and Klamath rivers in the US, which could similarly improve Chinook numbers.

Another method is to reduce how many salmon are caught accidentally, with Williams pointing to the rising popularity of the traditional reef-net fishing method used by the Lummi First Nation that allows for more selective catches.

“We can save [SRKW]. We just have to find the people who can do this stuff and give them resources that they need,” said Williams.

“This population can be saved. But it will require every tool at our disposal.”