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ESA-Listed Chum Salmon Operations Transition From Spawning Flows To Protecting Egg Incubation
Posted on Friday, January 11, 2019 (PST)

A survey of chum salmon redds December 21 downstream of Bonneville Dam found no spawning fish, triggering the transition from flows that protect spawning chum to flows designed to protect the redds during egg incubation.

 

The transition comes almost one week earlier than the transition planned by the interagency Technical Management Team at its Dec. 12 meeting, which was Dec. 26.

 

Washington Department of Fish and Wildlife biologists completed a survey of redds in the Ives Island/Pierce Island complex near the Washington side of the Columbia River, finding that no chum were present, according to Charles Morrill of WDFW and Tony Norris of the Bonneville Power Administration. Both were present during the survey, they said at TMT’s Jan. 2, 2019 meeting.

 

(See maps of chum spawning areas at http://pweb.crohms.org/tmt/agendas/2018/0117_Ives_Island_Spawning_Areas_2017.pdf.)

 

The chum, listed as threatened under the federal Endangered Species Act, arrived early this year and chum operations to protect the fish and their redds (nests) began Nov. 2, about a week earlier than normal. Operations for the chum go on for about five months into April, but generally transitions in late-December from spawning to chum incubation flows.

 

An email sent Dec. 21 to TMT members by Doug Baus of the U.S. Army Corps of Engineers said that the Bonneville Dam tailwater elevation for the incubation phase of chum operations will be maintained at a minimum 11.3 feet and will be effective through April 9, 2019, unless otherwise coordinated with TMT (see http://pweb.crohms.org/tmt/agendas/2019/0102_20181221_TMT_Coordination_Chum.pdf).

 

When protecting spawning salmon, chum operations ensure that enough water will flow over chum redds to protect the redds and fertilized eggs until they emerge in spring. Initial spawning operations seek flows high enough to protect chum as they build their redds, but not so high that chum would have been encouraged to spawn in areas that could be dewatered when flows drop.

 

Spawning operations maintain the dam’s tailwater elevation at a minimum 11.3 feet so that the fish can move into spawning areas near Hamilton Creek and Ives Island. However, fluctuations to higher tailwater elevations is limited to 13 feet.

 

For incubation, the tailwater elevation is set simply to keep water over the redds through incubation.

 

Flows at Bonneville are currently at about 132,000 cubic feet per second (Jan. 7) and that is expected to rise to about 142 kcfs this week (see NOAA’s River Forecast Center at https://www.nwrfc.noaa.gov/river/station/flowplot/flowplot.cgi?id=BONO3).

 

Also see:

 

--CBB, December 14, 2018, “Flows Managed To Aid ESA-Listed Chum Salmon Continuing To Arrive Below Bonneville Dam,” http://www.cbbulletin.com/441914.aspx

 

-- CBB, November 2, 2018, “ESA-Listed Chum Salmon Arrive Early Below Bonneville Dam; Flow Operations Begin To Protect Spawning,” http://www.cbbulletin.com/441754.aspx

 

--CBB, January 19, 2018, “Agencies Identify Spawning Areas For Chum, Confirm Safe Water Levels Over Redds,” http://www.cbbulletin.com/440103.aspx

 

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