The majority of adult spring Chinook, not 'some adult fish,' died in Butte Creek fish kill
By Dan Bacher |
In a recent website post entitled “The Myths and Facts — Sacramento Valley Salmon,” (norcalwater.org/...) the Northern California Water Association (NCWA) attempts to minimize the impact of a big fish kill this summer on Butte Creek.
The same assertions are found here on a later post: norcalwater.org/...
NCWA states:
• "The return of spring-run Chinook to the holding pools in the upper reach of Butte Creek this year was extraordinary and one of the largest runs seen in the past several decades, with estimates ranging from 15,000 to 20,000 adult fish.
• When the salmon reached their spawning grounds in the upper creek, the holding fish were exposed to periods of high temperatures, which appeared to be lethal for some adult fish.”
The first sentence is true, but the second, that the exposure of the spring Chinooks for periods of high temperatures "appeared to be lethal for some adult fish," is at best a huge understatement.
In reality, the majority, not "some of the adult fish," died before spawning because of disease spurred by low, warm water conditions. That’s backed up by the data available from the California Department of Fish and Wildlife’s snorkel surveys on the creek.
First, the CDFW detailed in a snorkel survey report on the creek that 12,370 salmon had died before spawning from June 1 to July 27, 2021. That's the majority of the 18,000 fish, not "some of the adult fish,” that the CDFW estimated ran up the creek this year to spawn: sacramento.newsreview.com/...
Second, the next CDFW snorkel survey reported that 14,500 fish out of the estimated 18,000 spring Chinook died before spawning by August 3.
Again, this is not "some adult fish," as the NCWA contends. It's the majority of the run, based on the estimate of 18,000 fish provided by the CDFW.
The good news is that the remaining fish that survived the lethally warm conditions have been spawning successfully on the creek. I will post the final data on the CDFW’s final numbers of fish that spawned and the pre-spawn mortality as soon as it becomes available.
According to Allen Harthorn, Executive Director of Friends of Butte Creek, in the Friends of Butte Creek newsletter on October 12, “The real test of the resilience of the Butte Creek Spring Run is happening as we write. Survivors by the hundreds are digging the gravel and doing their salmon dance. Spawning began around the 20th of September and continues in earnest through this writing.”
“Fresh female spawners were sighted October 11th. There should be at least one more week of activity. Water temperatures have plummeted, flows are good and the survivors will hopefully have reasonable success. The temperature extremes they faced could greatly reduce the success of the eggs. CFDW will be monitoring the out-migrants this fall and winter and we will keep you up to date as information is available,” stated Harthorn.
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