Two out of every three years, coho are basically extinct in the Deschutes River. But the Squaxin Island Tribe knows how to bring them back.
The tribe recently completed a recovery plan for coho salmon in the Deschutes. It found that a combination of habitat restoration in the upper watershed and the removal of a lower river dam to improve marine survival would recover the run within a few decades.
Restoring the river’s estuary would increase the number of coho that would return from the ocean as adults. “Estuaries are vital transition areas for salmon to go from fresh to salt water,” said Scott Steltzner, salmon biologist for the tribe. “If they don’t get what they need there, their ability to survive in the ocean plummets.”
Deschutes River coho runs were healthy through the late 1980s. A combination of declining ocean conditions and landslides in the upper Deschutes drove down the productivity of the run.
“Coho return every three years, so each year in a three-year cycle is a separate population of fish,” Steltzner said. “Only one of those age classes for Deschutes fish return in any numbers anymore; the other two are functionally extinct.”
The formation of a series of waterfalls centuries ago prevented salmon populations from establishing until the 1950s, when the state built a few fish ladders.
The recovery plan outlines habitat restoration projects that would reduce sediment, develop more complex habitat and lower temperatures. “There are a lot of problems in the watershed, mostly in the upper reaches of the river and its tributaries,” Steltzner said.
Restoring the river’s estuary is key to the effort.
“We could do everything else, be as aggressive as we can be in the upper watershed, and we wouldn’t see decent results until we increase the number of fish that come back from the ocean,” said Andy Whitener, natural resources director for the tribe. “The most logical way to do this is to restore the river’s estuary.”
Without restoring the estuary, the strongest age class of fish would top out at about 3,000 fish. The other two age classes would recover, but remain extremely low for decades.
According to the tribe’s model, a 1 percent increase in marine survival would triple the strongest age class in size. Within a couple of decades, the smallest age classes would be in triple digits.
“The Deschutes River is the largest and most important river in our treaty-reserved fishing area,” Whitener said. “By working hard to restore lost and degraded salmon habitat, we can bring back this run for the benefit of the tribe and our neighbors.”
