Chum salmon, long considered to be almost extinct on the Oregon side of the lower Columbia River, might again return to its tributaries if a cooperative effort of the Oregon and Washington departments of fish and wildlife proves successful.
The first week of April, the Oregon Department of Fish and Wildlife (ODFW) released 106,000 juvenile chum salmon into lower Big Creek in the first phase of project attempting to re-establish the species, which began to disappear from the Oregon side of the river more than 50 years ago. While the reason for their decline is not completely clear, biologists believe that severe habitat degradation, among other factors, played a key role.
The approximately 50 adult chum salmon male and female pairs used to produce the 2½ -inch fry at ODFW’s Big Creek Fish Hatchery were donated to Oregon by the Washington Department of Fish and Wildlife (WDFW). The adults were captured last fall in Grays River, a tributary of the lower Columbia on the Washington side of the river.
“Grays River stock are likely the most genetically similar to what once occupied Big Creek and other lower Columbia tributaries,” said Chris Knutsen, district fish biologist for ODFW’s North Coast Watershed. “We worked closely with our counterparts from WDFW to initiate this program in Oregon. We could not do this without fish from the Washington side of the river.”
The young salmon were released at night during an outgoing tide to increase their chances of getting past predators and surviving the 25-mile swim to the Pacific Ocean, where they will spend the next 3-4 years before returning to spawn at Big Creek.
“The quicker they get out under the cover of darkness and a strong ebb tide the better their chances of survival,” Knutsen explained.
Once the fish return to Big Creek most will be captured and spawned at Big Creek Fish Hatchery to produce more eggs and fry for release in subsequent years. Ultimately, ODFW hopes to generate enough seed stock to begin out-planting chum in other lower Columbia tributaries that are considered suitable for this species. Just which streams will be selected for future releases depends on which ones have the best conditions for chum, which Knutsen says are “very picky spawners.”
Chum salmon are generally more selective in their choice of spawning habitat than other salmon species, according to Knutsen. Chum especially seek out upwelling areas associated with springs and seeps, he said, and they also prefer very clean, well-sorted gravel that is free of sands and silts that could smother their eggs.
Dozens of streams around Scappoose and Clatskanie will be evaluated by ODFW research teams because biologists believe they show the greatest potential for establishing naturally-reproducing chum populations. Biologists also believe the timing is right for reintroduction because conservation measures and habitat improvements are already well underway in the region.
“Fortunately, we have four or five years to figure out which streams will work best because it will take us that long to generate extra fish for out-planting,” said Knutsen.
If the program works as planned, chum salmon will reproduce naturally in sufficient numbers that they will no longer need a boost from Big Creek Hatchery.
“Our goal is to develop self-sustaining populations of chum salmon on the Oregon side of the lower Columbia,” said Knutsen. If ODFW is able to bring back chum salmon in the lower Columbia using this approach, the same methodology might later be used to reintroduce chum salmon in areas further upstream, he said.