The California Department of Fish and Wildlife has just published their monitoring report on 2021's spring Chinook salmon run on Butte Creek, a tributary of the Sacramento River in Northern California.
The number of adult spring-run Chinooks that perished before spawning is worse than the preliminary estimate by the CDFW in October 2021, when the CDFW estimated that 14,500 out of 18,000 to 20,000 fish had perished before spawning.
In summary, the pre-spawning mortality of these endangered fish was estimated at only 19,773 out of 21,580 fish total. Only an estimated 1,807 adults survived to spawn.
Here are a couple of excerpts from the report:
"Using a modified Cormack Jolly-Seber (CJS) model (Bergman et al. 2012), the total SRCS population that did not survive to spawn in 2021 was estimated at 19,773. The carcass survey was conducted over 5 weeks from September 21 to October 21. A modified CJS model estimated the 2021 SRCS spawning population to be 1,807."
"The 2021 adult SRCS returning cohort was estimated at over 21,580, and based on field observations and survey estimates, the density of the population in the upper reaches of the holding habitat likely exacerbated the spread of pathogen transmission and contributed to the rapid spike in pre-spawn mortality."
The fish perished from disease in the crowded, warm water conditions on the creek.
The full report is available at: www.buttecreek.org
Fish advocates have criticized the California Department of Fish and Wildlife and other agencies for failing to exert needed pressure on PG&E, the current owner of the hydroelectric project on Butte Creek, to release colder flows when they were needed to alleviate the massive fish kill last year.
PG&E’s De Sabla/Centerville project brings West Branch Feather River water over the mountain from Phillbook Reservoir and Round Valley Reservoir to Butte Creek to be used for hydroelectric power.
“I’m still processing this fish kill,” summed up Allen Harthorn, Executive Director of Friends of Butte Creek, as the fish kill was in progress last year. “It’s mind-boggling. The agencies’ refusal to hold PGE&E’s feet to fire is pathetic – they need to get this hydroelectric project out of the way. They have been pussyfooting for years about installing a temperature control device at DeSabla Reservoir. We have to seriously talk about getting fish into cold water upstream and PG&E out of the way.”
The spring Chinook is one of four runs of salmon on the Sacramento River, including the spring, fall, late fall and winter runs. The spring and winter runs are listed under the federal Endangered Species Act (ESA) and the California Endangered Species Act (CESA).
This year’s spring Chinook run got off to a very rough start when over 200 adult spring Chinook perished in a slough connected to Butte Creek in the Butte Sink after flows were increased in the slough for irrigation purposes and then were slashed, resulting in the fish being left high and dry: sacramento.newsreview.com/…
For more information about the 2021 fish kill, read my August 2021 investigative news story in the Sacramento News and Review: sacramento.newsreview.com/…
I will be writing a longer article about the results of the CDFW report, but I wanted to get the news out now.
