A Salmon Shortage is Hurting Orca Whale Populations
Wild Chinook salmon are less abundant, and that's not just bad news for the fish monger.
There's an unsettling reason it's getting ever tougher to find fresh, unfarmed salmon at the store: salmon populations are depleting, with some species, such as the prized Chinook salmon along the U.S. West Coast, expected to vanish entirely in 100 years.
The endangered species that comprise the J, K, and L pods of orcas that swim from the Salish Sea to Seattle's waters are struggling to bring their pregnancies to term, according to research published this week in PLOS ONE, because the orcas—of which scientists estimate there are fewer than 80 left—aren't getting enough to eat of their primary food source: salmon. (Interestingly, while killer whales hunt other sea life, they are not conditioned to eat their prey—instead, they stick to the nutritionally-rich fish.)
Researchers followed the whales for seven years; in that time, 35 female orcas got pregnant, but only 11 had babies. And in their paper, they concluded, "pregnancy failure—likely brought on by poor nutrition—is the major constraining force on population growth." In other words, to save orcas, we've got to save salmon too.
Chinook salmon have long been threatened: they've lost their habitats to harvesting, urbanization, and dam development—plus pollution and other fish, the EPA says.
The researchers believe that reducing pollution could significantly increase the Chinook salmon population, which would provide the orcas with the food supply they need to reproduce. When the orcas don't get enough salmon, the researchers explain say, the animals starve. And when they starve, the animals metabolize fat cells that contain toxins—and those toxins, in turn, harm the orcas' pregnancies.
"Without steps taken to remedy the situation," the researcher say, "we risk losing the endangered [orcas], an important and iconic species to the Pacific Northwest."