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Heat blamed for Klamath fish kill

Dead tui chubs and fathead minnows float belly up Wednesday at the Miller Island boat ramp on the Klamath River. The small fish were among thousands of fish that died this week.

Published Thursday July 21, 2005


Thousands of dead fish were found belly up on the Klamath River southwest of Klamath Falls this week, the apparent victims of poor water conditions brought on by hot weather.

Among the dead are some young endangered sucker fish, but most of the fish are tui chubs and fathead minnows, and is no reason for alarm, federal officials said. The fish die-off was reported Tuesday morning by U.S. Bureau of Reclamation scientists, who said it occurred Monday evening.

Dead fish were found on a seven-mile stretch of the Klamath River below Lake Ewauna and in irrigation diversions on the river. The number of dead suckers were estimated to be "several thousand" suckers, said Rae Olsen, Bureau spokeswoman.

"Thousands is the only thing I can tell you," she said.

The dead suckers were found mostly near the Lost River Diversion Channel just south of Klamath Falls, said Roger Smith, fisheries biologist for the Oregon Department of Fish and Wildlife.

Afternoon highs have hovered in the 90s since last Thursday.

"And the day before that it was 86," Smith said.

The warm air makes for hot water. Water in the river was measured at 82 degrees at 4 p.m. Monday.

Suckers can tolerate 75-degree water for quite some time, but it still harms their health, he said.

Fish die-offs are common summertime occurrences that happen because of a combination of low water and high temperatures. When temperatures go up, the water quality goes down because oxygen levels are lowered by decaying algae, Smith said.

Although the warm water and algae blooms can prove fatal for suckers - especially those only about a year old - and tui chubs and fathead minnows, trout usually avoid the danger by swimming to cool pockets of water and away from the algae.

No dead trout have been found.

The die-off won't change how much water the Bureau releases from Upper Klamath Lake, Olsen said. Officials are required to conserve water in Upper Klamath Lake, where water quality is also poor and fish die-offs are a possibility during the summer.

"The most frustrating thing about this is there is nothing we can do," Olsen said.

Only cooler temperatures will help prevent fish die-offs. Temperatures are expected to cool slightly over the weekend, the National Weather Service said.





Page Updated: Thursday May 07, 2009 09:14 AM  Pacific

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