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Strong Summer Chinook Counts at Bonneville Dam Diminished by Warm Water Mortalities by Staff Columbia Basin Bulletin, August 7, 2015

"I just wanted to highlight that we had a record return... That indicates we had good ocean conditions and we had
good river conditions.... The problem is that we got hit with extremely poor river conditions" further upstream.

A NOAA Fisheries biologist reported this week that summer chinook migration amounted to a record at Bonneville Dam on the Columbia River, but the strong return was significantly diminished by high water temperature mortalities.

"I just wanted to highlight that we had a record return," said Trevor Conder, referring to his presentation to the Technical Management Team this week. "That indicates we had good ocean conditions and we had good river conditions. . . The problem is that we got hit with extremely poor river conditions" further upstream in the Columbia River system.

The count of summer chinook adults at Bonneville Dam has tallied about 161,000 fish. The previous highest count was 132,025 fish in 1957, Conder said.

"That was the highest by a large margin," he said, noting that the highest count of adult summer chinook salmon migrating at Bonneville in recent years was 126,000 fish in 2002.

"The flip side is that the conversion rates to McNary Dam (upstream from Bonneville) were lower than average," Conder said.

The mortality rates for chinook between Bonneville and McNary are similar to the rates for sockeye salmon, about 54 percent. Recorded mortality rates increase in waters further upstream, particularly for sockeye.

"We are seeing way more loss for Snake River sockeye," Conder said, referring to the segment of migrating spawners that move into the Snake River system as opposed to those that move into the Upper Columbia River system.

Related Pages:
Summer Chinook Return Forecasted to Be Largest Since 1961 by Staff, Columbia Basin Bulletin, 7/10/15

Why Are Thousands of Migratory Salmon Dying Before They Can Spawn? by Courtney Sherwood, Christian Science Monitor, 7/27/15
Biologists Bring Sockeye into ' on Trucks to Get Them Out of Hot Water by Rocky Barker, ' Statesman, 7/17/15
Sockeye Salmon Suffer Infections in Warm Columbia River System by Rich Landers, Spokesman-Review, 7/17/15
Half of Columbia River Sockeye Salmon Dying Due to Hot Water by Associated Press, The Oregonian, 7/18/15