Kokanee Face Dire Future Amid Effects of Climate Change

At least two local salmon species in the Puget Sound region may be near the end of their ability to naturally reproduce

There’s little good news these days for salmon in the Lake Washington watershed, and new information from researchers paints an even bleaker future for some of Washington state’s most cherished animals.

The number of kokanee salmon returning to spawn in the tributaries of Lake Sammamish was low again this year, prompting King County to start looking at ways to preserve this freshwater species. On top of this, local sockeye species that migrate to the Pacific Ocean hit record low numbers last year because an unknown disease, or combination of diseases, is wiping out the adult salmon when they return to Lake Washington.

In Lake Sammamish, around 100 kokanee returned to spawn this year, significantly higher than the 19 seen last year, but still much lower than levels that would indicate a healthy population. King County environmental affairs officer David St. John said the low number of returning fish provides evidence for their hypothesis that a lake condition known as “the squeeze” is killing the fish.

Kokanee, a freshwater variety of sockeye, have roughly three-year reproductive cycles, and some 230,000 kokanee fry entered the lake in 2016. Of the multitude that went into the lake, only around 100 returned this year, in line with the county’s worst-case scenarios. “It’s off-the-charts bad. Though this is not unexpected, it’s definitely the low end of the range that we thought was possible,” St. John said.

Lake Sammamish kokanee are a species of sockeye that spend their entire lives in the freshwater lake nestled between Sammamish and other large Eastside cities. Last year’s low numbers prompted biologists to begin examining courses of action in case this year’s count came in low, including a captive breeding program, where fish are raised in large tanks or ponds for three years until they spawn. This option is expensive, but was proposed after last year’s dismal counts. “We are actively exploring doing that with some of the fry that we have on hand now,” St. John said.

Aaron Kunkler, Bellevue Reporter

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