SEATTLE — Over the years, scientists have identified dams, pollution and vessel noise as causes of the troubling decline of the Pacific Northwest’s resident killer whales. Now, they may have found a new and more surprising culprit: pink salmon.<\/p>\n
Four salmon researchers were perusing data on the website of the Center for Whale Research, which studies the orcas, several months ago when they noticed a startling trend: that for the past two decades, significantly more of the whales have died in even-numbered years than in odd years.<\/p>\n
In a newly published paper, they speculate that the pattern is related to pink salmon, which return to the Salish Sea between Washington state and Canada in enormous numbers every other year — though they’re not sure how. They suspect that the huge runs of pink salmon, which have boomed under conservation efforts and changes in ocean conditions in the past two decades, might interfere with the whales’ ability to hunt their preferred prey, Chinook salmon.<\/p>\n
[Solving the salmon problem]<\/a><\/ins><\/p>\n Given the dire plight of the orcas, which officials say are on the brink of extinction, the researchers decided to publicize their discovery without waiting to investigate its causes.<\/p>\n “The main point was getting out to the public word about this biennial pattern so people can start thinking about this important, completely unexpected factor in the decline of these whales,” said one of the authors, Greg Ruggerone. “It’s important to better understand what’s occurring here because that could help facilitate recovery actions.”<\/p>\n Ruggerone, president of Seattle-based Natural Resources Consultants and former chairman of the Columbia River Independent Scientific Advisory Board, and the other authors — Alan Springer of the University of Alaska at Fairbanks, Leon Shaul of the Alaska Department of Fish and Game, and independent researcher Gus van Vliet of Auke Bay, Alaska — have previously studied how pink salmon compete for prey with other species.<\/p>\n