Agencies cite unusual conditions in fish kill
BEND — Fish biologists attribute the deaths of about 3,000 fish in a side channel of the Deschutes River in Central Oregon to several unusual conditions, including better than average rainfall the previous two years.
About 450 trout, and about 1,200 each of mountain whitefish and sculpin were found last week in a half-mile stretch of the river upstream of Bend, according to a statement from Oregon fish and wildlife and water resources agencies.
Among the trout were redband rainbows, a species the state lists as sensitive, the Bulletin newspaper of Bend reported.
The numbers are an estimate, and probably too low, said Erik Moberly, assistant district biologist with the state Department of Fish and Wildlife.
According to a statement issued by Moberly and other scientists, two good water years in 2011 and 2012 meant the channel didn't completely dry up, so there were more fish in it than would normally be the case.
“With any natural or manipulated flows in rivers throughout the state we can see events like this,” Moberly said. “This shouldn't create any long-term threat to fish populations.”
In the fall, the river level drops as releases from Wickiup Reservoir southwest of Bend are slowed so that water can be collected for next year's irrigation season.
State agencies will continue to investigate whether that process contributed to the fish deaths, but biologists said that what's called the “ramp down rate” was slower this year than in previous years.
The statement said that “... a slower ramp down rate is considered to be better for fish, leading water and fishery managers to look for other explanations why so many fish were stranded in the channel.”
Greater numbers of fish came out of the reservoir this year, the statement said, and the stream got a large influx of water from September rains, just before conditions turned dry.
Information from: The Bulletin, http://www.bendbulletin.com