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Temps Rising; McNary Fish Collection, Barging Begins

by Mike O'Bryant
Columbia Basin Bulletin - July 12, 2002

Saying that spring-like conditions no longer exist, the National Marine Fisheries Service asked the U.S .Army Corps of Engineers to begin barging juvenile salmon and steelhead migrants at McNary Dam.

"Given the change from spring to summer-like conditions, round 'em up, head 'em out," said Paul Wagner of NMFS at this week's Technical Management Team meeting. Other TMT salmon managers concurred with the decision.

Wagner said that, with river temperatures on the rise (tailwater temperature at the dam was 62 F on July 10) and flows (210,000 cubic feet per second July 10) declining at the dam, it is time to begin the operation. However, with 50 percent of subyearling chinook migrants already having passed through the dam, he expects that only a quarter of this year's migration will be barged.

Rudd Turner of the Corps said the agency could begin collection immediately (July 10).

The question whether transporting fish by barge from upriver dams to below Bonneville Dam helps or hurts juvenile salmon is still undecided. However, Wagner said that when conditions change from spring to summer some transportation studies show there is a benefit to barging the fish around dams. In addition, the 2000 BiOp calls for the change when seasonal conditions change.

Still, collecting fish at some dams causes additional stress on fish, especially at Lower Monumental Dam on the lower Snake River and at McNary Dam. Stress levels at Lower Monumental are higher than at other collection facilities, such as those at Lower Granite and Little Goose dams, also on the Snake River, and some fish experience injuries, Wagner said. The reason is up to a 6-foot drop from the holding facility to the barge. "The gradient is steep and the distance is short," he said. The design of the collection facility at McNary Dam is similar. "The physical construction of these facilities could be contributing to lower SARs (smolt to adult return ratio)," Wagner concluded.

Related Sites:
Technical Management Team

Mike O'Bryant
Temps Rising; McNary Fish Collection, Barging Begins
Columbia Basin Bulletin, July 12, 2002

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