FILE- In this Jan. 18, 2014, file photo, an endangered female orca leaps from the water while breaching in Puget Sound west of Seattle, Wash. For 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. Salmon researchers perusing data on the website of the Center for Whale Research 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. In a newly published paper, they speculate that the pattern is related to pink salmon, which return to the waters between Washington state and Canada in enormous numbers every other year. (AP Photo/Elaine Thompson, File)

Scientists ID another possible threat to orcas: pink salmon

January 18, 2019 - 2:52 pm
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SEATTLE (AP) — 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.

Four salmon researchers were perusing orca data 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.

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. They suspect the huge runs of pink salmon, which have boomed under conservation efforts and changes in ocean conditions in the past two decades, interfere with the whales' ability to hunt their preferred prey, Chinook salmon.

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