April 13, 2024

Southern Resident Orca Extinction Risk Accelerates as Researchers Raise Alarm

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Orca scientist Rob Williams always thought conservation was a knowledge problem, that once science showed why a species was in decline, people would solve the problem.

But new research concludes otherwise. Even in the case of one of the world’s most charismatic species, the endangered southern resident killer whales that frequent Puget Sound face an accelerating risk of extinction, a new population analysis shows.

Despite everything we know about them and why they are in decline, this beloved species is heading towards extinction in plain sight – a danger that the scientists who published the paper memorably call the “Brilliant Extinction”, the oblivion happening right before our eyes.

“There is no scenario in which the population is stable,” said Williams, co-founder and chief scientist at the nonprofit research organization Oceans Initiative, and lead author of the paper published in Nature Communications Earth and Environment. “We have a generation or two where the population doesn’t fluctuate around zero, it fluctuates around a decline, and then accelerates to a faster rate of decline until extinction. -opener. That’s what the status quo will do.

In their model, the scientists found that the population of southern residents declined until it fell off a cliff in about 50 years – two generations of killer whales – leaving only about 20 members of their family within a century. Taking growing threats into account would make the picture even worse.

This, Williams had to face, is not a problem of adequate information. Rather, it is a matter of inappropriate action. “I assumed if we had the right data we would make the right decisions. But…not only do we know their biology and the threats they face,” he said of southern residents, “we’ve known these things for a long time.”

Climate change increases the risk of extinction.

Warming ocean water disrupts oceanic food chains that feed Chinook salmon – the killer whales’ main prey. And warming rivers harms salmon survival and reproduction. Other threats, including shipping traffic and other noise that disrupt orca hunting and habitat destruction, are also intensifying. Changing the environment is making it, at this rate, a place where these co-evolved animals can no longer live.

Carl Safina, study author, ecologist and professor of nature and humanity at Stony Brook University in New York, sees the condemnation of species extinction and the imminent loss of southern residents as a moral test for people.

“This is like a collision in slow motion; this is where we see the brick wall or the cliff, it’s clear, the road is dry, it’s 11 o’clock on a Sunday morning and we’re going eight miles an hour, and it’s half time a kilometer away, and then a quarter of a mile away, and then we see this, and our smart sensors start beeping, and then we step on the gas and hit… why do we do this?”

Laws alone are clearly not enough: The Endangered Species Act, which turned 50 this year, calls for the preservation of all species, no matter how lowly. Yet here is one of the most intelligent animals in all the oceans, and its top predator, barely hanging on.

What’s needed, Safina said, is a fundamental change in the way we all live here.

“Socially, we need an ethic that values ​​life on this planet and that sees us as stewards.”

The condition of southern residents is so dire – there are only 74 left – that it may be time to consider more drastic interventions, including preventive vaccination of at least some of the most biologically valuable members, the articles’ authors say. You also need to develop a plan to be prepared for a catastrophic event, such as a disease outbreak that requires a veterinary response at the U.S.-Canada border.

To give southern residents a better opportunity for hunting success, the paper recommends some sweeping changes. Voluntary slowdowns already in place for ships were found to reduce noise levels by nearly half, according to the paper, which in turn results in increased hunting activity by killer whales.

However, at the same time, several development projects are underway that will increase shipping traffic in the region, with the completion of the second TransMountain oil sands pipeline, which terminates at the Port of Vancouver, and a major expansion of the marine terminal in Roberts Bank, the Roberts Bank Terminal 2 Project, planned right in the Fraser River Delta where orcas hunt.

Perhaps it’s time to consider budgets, caps, or mandatory caps on ocean noise to allow killer whales to hunt scarce prey more effectively, the paper concluded.

A new look at fisheries management is also needed, according to the document, to leave more fish in the sea for the orcas. Moving fisheries in Alaska and British Columbia away from Chinook breeding grounds and offshore migration routes to river mouths and estuarine locations would result in an immediate increase in orca-critical Chinook by up to 25%. according to the newspaper.

This fishery could also help recover a Chinook population more similar to the one that orcas evolved from. By not catching immature fish in offshore fisheries and allowing large females to pass to spawning grounds, an increase in Chinook size of up to 40 percent could occur over a 50-year period, according to the paper. This would provide more of what large Chinook orcas need and prefer. Freshwater habitat restoration could also continue to support the abundance of wild Chinook, rather than releasing more hatchery fish into the sea.

Hatchery fish compete with wild fish for food and spawning area. They can also weaken the fitness of wild Chinooks through inbreeding or disease, noted study author Misty MacDuffee, a salmon biologist at the Raincoast Conservation Foundation, a nonprofit scientific organization. She sees no path to orca recovery without fisheries reform and other changes to protect orcas’ preferred food.

Another recent article published in the peer-reviewed journal Ecosphere examined the relationship between prey availability and the ups and downs of the southern resident population, to investigate how these relationships may have changed over time.

The work confirmed the essential connection between southern residents and their preferred food. “Prey is still important,” said Eric Ward, paper author and scientist at the National Oceanic and Atmospheric Administration’s Northwest Fisheries Science Center. The paper also found that northern resident orcas – whose population is increasing – may be affecting the survival of southern residents due to competition for the same food in shared waters.

Joe Gaydos, scientific director of the SeaDoc Society, a nonprofit scientific research and education organization and author of the Nature paper, said the population analysis was a wake-up call about the risk southern residents face without a change of course. What he hopes now is that decision-makers and the public will use this information to step up efforts to save a species that defines much of the region’s wonder.

“We’ve done a lot of good things for southern residents and we need to do more,” Gaydos said. “It’s like when people go to the doctor at age 60 and say, ‘Should I eat better, stop smoking, stop drinking, and exercise?’ and the doctor says, ‘Yes, and you need to do all of that and you should have that. That’s been 20 years.” That’s what this newspaper is saying.

“We don’t have time. We’re talking about making big changes to the next generations of orcas, or we’ll run out of time.”

That doesn’t make this new work documenting southern residents’ accelerating extinction risk a document of lost hope, Gaydos said, but quite the opposite.

“Now is the time to show the money and make the effort.” On the one hand, we owe it to these animals, Gaydos noted.

Southern residents are in trouble, in part because of the capture era, during which a third of whales were taken for sale to aquariums and other entertainment venues.

“We just need to do what we need to do, make it happen, it’s on us, we got them here. We are the reason they are threatened,” Gaydos said of the southern residents. “First with the catches, and then with the salmon and the contaminants that we produce; those don’t occur naturally and those are our boats out there.”

Tim Regan, former executive director of the U.S. Marine Mammal Commission who was not an author on the paper, says it’s not over yet for southern residents. “I personally would say it’s never too late,” Regan said. Other species, from elephant seals to cranes, have made remarkable comebacks, even in difficult situations.

Southern residents are the top predators in these waters and symbolize the wonder of our natural environment and a commitment to other life forms that we value, Regan said.

“They are a beautiful reminder of the nature of other species. If we don’t care about them, I don’t know what we would care about.

“You can’t be blamed for failing, but you can be blamed for not trying.”

More information:
Rob Williams et al, Warning sign of an accelerating decline in critically endangered killer whales (Orcinus orca), Earth and Environment Communications (2024). DOI: 10.1038/s43247-024-01327-5

Diary information:
Nature Communications Earth and Environment


Earth and Environment Communications

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