There is no doubt that flooding this year in the Mat-Su Valley, the Kenai Peninsula and in Seward have caused big disruptions in the lives of people -- but what is it doing to salmon?
In the Kenai River, Coho (Silvers) are making their annual runs at the very moment that huge currents -- generated by flooding -- are washing downstream. Those currents are sometimes capable of scouring river bottoms, and forcing salmon eggs that have been buried in the sediment to flow out to sea.
Wildlife experts say it's possible that this month's flooding could adversely affect Coho runs 2-to-4 years from now. But they also say a major impact on the run is far from certain.
For one thing, even river currents on the Kenai were fast and forceful this week, it's far from clear that they had the same scouring force on the very bottom of the river as they had near the surface.
For another, evolution has prepared the salmon to deal with the flooding. When salmon are stressed by rapid flood currents, they will often delay spawning for several days -- so that their eggs can be laid in more stable bottom sediments.
And finally, salmon do not lay their eggs all at once. The Coho run will last for weeks. And only eggs laid up to now are vulnerable to the floodwaters' scouring erffects.
Nevertheless, floods are believed to have adversely affected salmon runs in Alaska in previous years.
It's possible that the Mat-Su flooding of 2006 harmed subsequent runs of salmon. And flooding in Alaska in the mid 1980's is also believed to have had adverse effects on some salmon runs.
But it's hard to say for sure because salmon -- in their normal life-cycle -- face so many obstacles in addition to flooding.
So no one can say, with certainty, whether this year's flooding will harm the return of the Coho in 2014 through 2016. No measurements are made of river-bottoms for the scouring-out of salmon eggs. The only way we will no for sure is when this year's hatchlings come back to spawn.
Even then, say marine biologists, it may be difficult to pin down an exact cause for any alteration in salmon runs. That's because the fish face a gauntlet of obstacles before they return to the rivers in which they were born. They are eaten by predators, caught by deep-sea fishermen, can suffer starvation when a cold-water upwelling known as the Pacific Decadal Oscillation impacts them.
Sorting out which of these factors is responsible for the diminished size of any given salmon runs is a difficult task. Sometimes it may be a combination of several factors that influences the strength of a run.
Nevertheless, 2012 will go down as the year that the Kings failed to return to Alaska.
And no one can rule out the possibility that it may also be the year that flooding harmed the size of the Coho return in future years.
Contact Dan Fiorucci
