High waters on the Kenai River prompt concerns for residents — but not salmon population

The Kenai river has had high waters this week after two glacier dammed lakes emptied out in the river.
Published: Sep. 14, 2023 at 4:31 PM AKDT
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ANCHORAGE, Alaska (KTUU) - The Kenai River has had high waters this week after two glacial dammed lakes emptied out in the river.

The Alaska Department of Fish and Game said current flooding conditions are common and are not a concern for salmon. But if levels rise, the Kenai’s salmon populations could see struggles.

A 2016 study published in the journal Global Change Biology reported that “increased flood size could alter stream habitats used by Pacific salmon for reproduction, with negative consequences for the substantial economic, cultural, and ecosystem services these fish provide.”

Increasingly warmer and wetter climates in Southeast Alaska during the last century have been identified as areas of concern “about climate impacts to salmon ecosystems and the economic, cultural, and ecosystem services they support,” the report said.

The report adds that, “ the combined effects of regional warming and increased mean annual precipitation are likely to increase the magnitude of flood disturbance on salmon ecosystems.”

Matt Miller, the Department of Fish and Game’s Cook Inlet Sport Fish Regional Coordinator, said the impact of flooding on fish populations depends on what type of flooding occurs.

“If it’s just a high water event, the juvenile fish are going to move on to some place else. But sometimes you get more dramatic events where the flood will scour through the river and tear up where the spawning beds were,” Miller said.

In cases of extreme flooding with a lot of debris, Miller said it can wipe away eggs that were laid in spring. But species like the king salmon have a spawning strategy that helps them avoid a high population loss.

“For king salmon, they’ve evolved this great spawning mechanism where they stay out in the ocean for multiple years, and so even if you were to lose the significant part of a spawning year they’ve got multiple age classes coming back. So the impact is kind of mitigated that way,” Miller said.

Coho salmon — or silver salmon — will also take advantage of the higher water levels and explore new areas.