Flood waters give rise to low fish return

Posted: Wednesday, October 25, 2006

 

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  The water allowed fish to swim into areas they might not otherwise go. Photo by M. Scott Moon

A coho salmon scurries across Dairy Hill Lane at a roadblock in Seward as a motorist chooses another course to follow during flooding earlier this month. The high water could affect the 2010 return of wild coho salmon, according to fisheries biologists.

Photo by M. Scott Moon

Earlier this month, Seward area residents blundered about bewildered as floods swamped their neighborhoods. But humans were not the only creatures confused as their habitat went topsy-turvy.

While people struggled to escape soggy homes and businesses, coho salmon lost in the watery chaos, crossed roads and wiggled into swampy lawns, where they spawned their doomed broods.

And while coho that spawned before the floods avoided the watery chaos, they, too, may fail to pass on their genes.

“(Coho) that spawned during or before the flood probably had their eggs wiped out of the gravels,” said Gary Fandrei, executive director of the Cook Inlet Aquaculture Association. “They were either buried deeply under other sediment or were scoured out and washed downstream.”

Flood impacts on Resurrection Bay Drainage salmon runs likely will be minimal for sockeye and chinook salmon.

But while the damage may be difficult to gauge, biologists expect this year’s flood event will put a dent in the drainage area’s returning 2010 coho run.

 

The water allowed fish to swim into areas they might not otherwise go.

Photo by M. Scott Moon

The Resurrection Bay Drainage’s chinook originate almost entirely in hatcheries, as does 95 percent of the drainage’s sockeye run. But 20 percent of the drainage’s coho run is produced by fish spawning in the wild and remains vulnerable to flooding events such as the one that occurred earlier this month, said Caroline Cherry, MariCal research scientist based at the Alaska SeaLife Center in Seward.

However, Cherry didn’t predict catastrophically low coho runs for the drainage area since most of its coho fry are hatched and raised in a sheltered environment.

“They’re nice and safe in the hatchery,” she said.

Wild coho salmon eggs that survived this year’s floods in the drainage area to hatch as fry in 2007, will smolt out to the ocean in 2009 and return in 2010, Fandrei said.

But due to the floods, the 2010 coho run, which in a normal year would depend on wild spawned salmon for 20 percent of its fish, may dip below normal returns.

“When these fish go out that were just laid this fall, there will be less of those going out, and hence you’re going to have less coming back, unless of course the enhancement component increases,” Cherry said.

More hatchery coho smolt could be released to make up for a shortfall in wild coho smolt if the Seward City Council, chamber of commerce or SeaLife Center offer Cook Inlet Aquaculture Center additional funding to boost its enhancement program in the Resurrection Bay Drainage area, Cherry said.

However, she said she thought it was unlikely to happen.

Patrice Kohl can be reached at patrice.kohl@peninsulaclarion.com.



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