Flooding's impact on salmon tough to predict

Beth Bragg

It will be years before we know how -- or even if -- the recent flooding and high waters will affect Alaska's salmon.

The potential for fewer fish in the future exists, said Bob Clark, the Alaska Department of Fish and Game's chief scientist for sport fish.

Fish production could dip if fast-moving water scours spawning sites of eggs, he said. And fewer juveniles may survive if those that wind up in flood plains don't find their way back into rivers once flooding subsides.

For now, though, no one can accurately predict what will happen.

"It's too early," Clark said. "The way we sort of evaluate some of these environmental effects -- freezing, flooding, not enough snow, too much snow -- at least for salmon is when they come back as adults."

For pinks, that means two years from now, Clark said. It'll be three to four years to know about silvers and reds and four to seven years for kings.

"Anytime we get this catastrophic kind of flooding where there's lots of gravel being moved around, you wonder about spawning success," he said.

But it's not just eggs that are at risk.

In the mid-1980s, flooding of the Susitna River altered salmon production for a couple of years, but it also did something else, Clark said. "It moved a bunch of pike around," he said, "and the dispersal of pike into that drainage has caused some problems."

Other species, like trout and Dolly Varden, could lose an important source of food if dead salmon are washed out of rivers.

"It takes food away from the fish," Clark said, "but it also creates more food, because you get more insects and there's more movement of leaves into the system."

Clark emphasized that salmon are adaptable. Those that populate rivers prone to flooding are particularly adaptable, he said, and silvers in general are especially adjustable.

"Cohos are really good at handling floods," he said. "They'll move upstream and spawn in areas they (usually) can't get to, which can cause good production.

"So there are positive effects. I hate to say that with all the fallen trees and flooded golf courses, but cohos are really, really adaptable."

Reach Beth Bragg at bbragg@adn.com or 257-4335.

Anchorage Daily News