Salmon, rivers hit hard by recent Washington floods

The atmospheric river that hit the Pacific Northwest in early December took a heavy toll on salmon, biologists working with Puget Sound tribes say.

You might think all the rain that comes with the storm systems known as atmospheric rivers or Pineapple Expresses would be good for fish.

But tribal biologists say major floods have hit salmon-bearing rivers hard two out of the past three autumns, at a time when freshly laid Chinook salmon eggs are incubating in their underwater nests.

“We've had two flooding events that, over three years, have hit during this time that we know all the Chinook eggs are in the gravels,” said fisheries researcher Mike LeMoine with the Skagit River System Cooperative, a project of the Swinomish and Sauk-Suiattle Tribes. “It's right after Chinook complete their spawning.”

Extreme flows can kill salmon eggs in two ways: scouring eggs and their shallow nests out of a riverbed or entombing them in mud.

“A big event will deposit a bunch of sediment over the top of the eggs and smother them, and they call that entombment,” said Jason Griffith, a Stillaguamish Tribe of Indians biologist.