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NW Fishletter #372, August 7, 2017

[9] Power Council Gets Update on Lower Columbia River Chum Recovery

Upswings in the number of lower Columbia River chum in 2015 and 2016, and a strategic focus on restoration, hold promise for the threatened species, the Northwest Power and Conservation Council learned at its July 11 meeting.

Historically, a half-million to a million Columbia River chum salmon returned to the river annually to spawn as far upstream as Celilo Falls, biologist Todd Hillson told the Council. Hillson is chum project leader for the Washington Department of Fish and Wildlife.

That began to change in the 1940s, he said. Now chum returns range from 1,000 to 10,000 each year.

Hillson said reasons for the enormous reduction in chum abundance include overfishing; the 1938 completion of Bonneville Dam that flooded chum spawning habitat; and the loss of off-channel and braided habitats, particularly in the lowest portions of rivers where towns were built and agriculture prevails.

His July 11 update described the status of four Columbia River chum populations--Grays River, Lower Gorge, Washougal River and the Upper Gorge.

These chum and other mostly smaller lower Columbia River populations were listed as one evolutionarily significant unit under the Endangered Species Act in 1999.

The strongest population is in Grays River, a Washington stream about 15 miles upstream of the Columbia River mouth. The Grays' returns have been above the delisting goal of 1,600 fish for the past 15 years. Last year's total run size back to the Grays was about 12,300 fish, the highest level recorded in the past 15 years.

This rebound in spawner abundance prompted NOAA Fisheries in a 2016 status review to declare the population at low risk of extinction.

Hamilton Creek spawning channel. Credit: Federal Caucus

Hillson said that for the Lower Gorge population, eight of the past 15 years have brought runs above the delisting goal of 2,000 adult chum, while about 3,400 chum spawned near Bonneville Dam in 2016. Most of the Lower Gorge population spawns in areas between the Interstate 205 Bridge near Portland and Washougal, Wash., upstream.

The Washougal River population had a 2016 return of 3,120 adult chum. The delisting goal of 1,300 chum has been exceeded in nine of the last 15 years.

NOAA Fisheries' 2016 review said Lower Gorge and Washougal River populations are each "maintaining moderate numbers and appear to be relatively stable." Over 1,000 are returning annually to the two areas.

For the Upper Gorge population, it's a different story. Hillson said that even in 2016, when overall chum returns were good, only 115 made it back to this area, which extends from Bonneville Dam upstream as far as the Hood River.

The spawning goal for delisting Upper Gorge chum is 900 fish. Since 2002, returns have been in the range of 100 adult chum. The population includes the Big White Salmon River drainage in Washington and the Hood River drainage in Oregon.

The recovery approach, Hillson said, emphasizes habitat restoration and creation, supplementation and reintroduction, and monitoring.

Habitat creation, said Hillson, refers to building spawning channels until natural processes re-establish "high quality off-channel habitats."

Spawning channels are being used at Duncan and Hamilton creeks downstream of Bonneville Dam. Two in Skamokawa Creek, which is one drainage east of Grays River, are expected to be completed this summer. Other spawning channels are planned in the North Fork Lewis River, the Elochoman River and in Oregon's Sandy River basin.

Grays River hatchery stock provides a means to jump-start populations in Duncan, Skamokawa and Elochoman creeks through reintroduction and supplementation, and to supply eggs to the Oregon Department of Fish and Wildlife for a hatchery program that will reintroduce the species in Oregon.

To jump-start chum restoration in the Lewis River, WDFW will use fish from the Lower Gorge population near I-205."> Operations at Bonneville Dam have also been adjusted to protect vital spawning and incubation areas below the dam. Starting annually in November, the project is managed to minimize tailwater fluctuations to enable main-stem spawning and avoid dewatering chum eggs nestled in the rocky gravels called redds.

In addition, Hillson said, the incidental harvest of chum is set at less than 5 percent annually.

BPA, several NOAA Fisheries programs and the Washington Department of Ecology fund chum restoration. -Laura Berg

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