La month, the sick killer whales in the Pacific gave researchers a rare moment of hope: a new calf was seen swimming with its mother. Until then, only one calf had appeared this year, only to die a few months later.
But in mid-October, this new calf, named L128, also appeared to be succumbing to ill health and appeared “lumpy and emaciated” when researchers from the Center for Whale Research saw an older killer whale swimming with the infant draped across its snout.
Another whale was “shaking the calf as if they were desperately trying to revive it”. Mark Malleson, a field biologist, believed he saw the calf “take a weak breath” and resume swimming, the center said, but it is unclear if she is still alive.
The unfolding tragedy of the critically endangered southern orcas has long been seen as a reflection of an ecosystem in crisis, prompting bitter recriminations between fishermen, whale watching companies and the shipping industry.
Underlying the blame is a belief that whales lack access to chinook salmon – their main food source and a species that has also suffered catastrophic collapse.
But a new study from the University of British Columbia has changed that assumption, revealing that the whales have far more access to chinook salmon than their much healthier relatives, the northern killer whales. The new findings deepen the mystery of what is pushing whales to the brink of extinction.
“It really surprised us. And you look at your data very carefully, because you’re sure you’ve made a mistake somewhere. You check everything three times, and then you go through peer review and still have the same numbers, ” said Andrew Trites, the report’s co-author and director of the marine mammal research unit at the university.
The research, published in the journal Plos One, studied the availability of food for the southern residents, an ecotype of 73 cetaceans spanning a geographic range from southern British Columbia to California. Divided into three pods, the whales spend their summers beaching off the coast of Vancouver Island. The team also looked at the food availability of northern killer whales, a growing population of 34 pods that spans Alaska to southern British Columbia, and overlaps with the southern right whales around Vancouver Island.
“If you ask anybody beforehand what we would find, it’s quite obvious: there just aren’t enough fish for the southern residents,” Trites said. But after meeting anglers and whale watching teams, the team found a relative amount of chinook available to the southern resident whales.
“It seems that access to food in the Salish Sea, where we have put all these protections and restrictions in place, is not really the 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 the diet in the winter and spring? This is where the bottleneck may be. So we might spend so much time focusing on our own backyard that we don’t consider what happens when they’re not in our backyard.”
Although the whales have better availability of prey, Trites warned that this does not mean they can access the fish.
The study found that noise from marine traffic can “mask” communication between killer whales and interfere with their ability to hunt. The presence of large ships can also hamper their foraging efforts.
“Orcas are more likely to encounter a greater number of vessels in the Salish Sea than in the north [Vancouver] island waters, which may mean that salmon are less available to southern residents than to northern residents despite a higher abundance of chinook,” the study said.
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Environmental groups have long worried about the effects of increased shipping traffic along 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 a liquefied natural gas (LNG) terminal is opened.
“There is no doubt that the southern killer whales encounter more ships and ship traffic. Can they adapt to it, or is it another straw on their backs that adds stress that will just make it even harder for them to recover?” said Trites.
As Trites notes, the population of killer whales in the south has remained relatively static for more than half a century, although it is believed to have numbered more than 200 in the early 20th century.
Much of the decline can also be traced to a dark history in the early 1900s, when the whales, called “blackfish” by fishermen, were slaughtered and later captured en masse for use in aquariums. The population only got respite when Canada banned the capture of killer whales in the 1970s.
“When you look at the marine mammals in the Salish Sea, the only ones in trouble are the southern residents,” Trites said. The nutrient-rich waters of the Salish were once home to large populations of whales, until rampant whaling nearly pushed humpback and fin whale species to local extinction. However, an end to widespread slaughter has allowed populations to increase. The waters now have a record number of harp seals with healthy populations of California sea lions and porpoises.
“And so the only outlier is the southern killer whales,” Trites said. “Is it a problem with the Salish Sea? Or are they bringing their problems with them?”