‘Access to food is not the problem’: new orca study sheds light on mystery of vulnerability

LLast month, sick whales in the southern Pacific gave researchers a rare moment of hope: a new calf was seen swimming next to its mother. Until then, only one calf had been born this year, and it died a few months later.

But in mid-October, this new calf, named L128, also appeared to be suffering from poor health, appearing “chubby and emaciated” when researchers at the Center for Whale Research looked at the orca an old woman swims with a baby in her nose.

One whale “raised the calf, as if trying hard to revive it”. Mark Malleson, a field biologist, believed he saw the calf “breathing a little” and start swimming, the agency said, but it was unclear if it was still alive.

The ongoing slaughter of endangered southern right whales has long been seen as a sign of an ecosystem in crisis, prompting strong criticism among fishermen, whale watching companies and the maritime transport industry.

The culprit is the belief that the whales cannot find chinook salmon – their main food source and a species that has also been severely depleted.

But a new study from the University of British Columbia raised that idea, revealing that the whales are more likely to find chinook salmon than their healthy relatives, the orcas of the northern population. New research deepens the mystery of what is pushing whales to the brink of extinction.

We were very surprised. And you look at your notes very hard, because you are sure that you have made mistakes somewhere. “You triple check everything and then you go to peer review and you still have the same numbers,” said Andrew Trites, co-author of the report. is director of the university’s marine animal research department.

The research, published in the journal Plos One, examined food availability for the southern population, an ecotype of 73 whales that range from southern British Columbia to California. The whales, divided into three pods, spent their summer and beached on Vancouver Island. The team is also looking at the food availability of northern orcas, a growing number of pods of 34 from Alaska to southern British Columbia, which meet with southern right whales around the Island of Vancouver.

“If you ask anybody ahead of time what we’re going to get, it’s clear: there’s not enough fish for the southern population,” Trites said. But after meeting with sport anglers and whale watchers, the team found enough chinook available to the southern right whales.

“It seems that access to food in the Salish Sea, where we have put all these protections and restrictions in place, is not a problem. When you think about food for southern killer whales, you have to think about food every day of the year, not just when they’re in the Salish Sea in the summer and fall,” Trites said. What about winter and spring foods? This is where the problem may lie. So we may spend so much time focusing on our yard that we don’t think about what happens when they are not in our yard. ”

Even though whales have better prey, Trites cautioned, that doesn’t mean they can catch fish.

The study found noise from marine traffic can “smell” communication between orcas and interfere with their ability to hunt. The presence of large ships can also hinder their foraging efforts.

“Killer whales tend to encounter more ships in the Salish Sea than in the north [Vancouver] Island waters, which may mean that salmon are less readily available for southern residents than for northern residents despite the abundance of chinook,” the study said.

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after the news release

Environmental groups have long been concerned about the effects of increased boat traffic on the southwest coast of British Columbia, with an increase expected in the coming years as construction of the Trans Mountain oil pipeline ramps up and the gas plant expands. natural (LNG) which is increasing. open.

“There is no doubt that southern right whales are coming into contact with a lot of ships and boat traffic. Can they adapt to it, or is it another straw on their backs, adding to the pressure that will make it even more difficult for them to have they recovered?” said Trites.

As Trites notes, the population of southern orcas has remained stable for more than half a century, though it is believed to have peaked at more than 200 at the turn of the 20th century.

Much of the decline can also be traced back to a dark history in the early 1900s when whales, called “blackfish” by fishermen, were slaughtered and later caught in large numbers for use in marine fisheries. The only reprieve for the population was when Canada banned the capture of orcas in the 1970s.

“When you look at the mammals in the Salish Sea, the only ones that have problems are the southern populations,” Trites said. The nutrient-rich Salish waters were once home to large numbers of whales until overpopulation nearly drove humpback and fin whale species to extinction in the area. However, the end of widespread killing allowed the population to increase. The waters are teeming with record numbers of harp seals, with healthy populations of California sea lions and porpoises.

“So, the only ones out there are the killer whales in the south,” Trites said. “Is it a problem with the Salish Sea? Or are they bringing their own problems with them?”