Update: A Record 34,740 Salmon Return to Mokelumne River, Upper Sacramento Run Is Dismal

CLEMENTS, CA — A record high number of fall-run Chinook salmon have returned to California’s Mokelumne River to date, while an alarmingly low number of Chinooks have come back to the Upper Sacramento River’s Coleman National Fish Hatchery on Battle Creek.

A total of 34,740 fish have gone over the Woodbridge Diversion Dam on the Mokelumne near Lodi through Dec. 13, according to Michelle Workman, Fisheries and Wildlife Manager for the East Bay Municipal Utility District (EBMUD). 25,429 of those fish were adults, while 9,303 were grilse (male/female 2 year olds). Those numbers don’t add up to the total because a handful of early fish could not be sorted by male/female. 

The previous salmon record was set last year when the total run size was 28,865, said Workman.

The Mokelumne is a 95-mile-long river in northern California that flows west from the rugged central Sierra Nevada into the Central Valley and then into the Sacramento–San Joaquin River Delta, where it empties into the San Joaquin River-Stockton Deepwater Shipping Channel. 

The Mokelumne River Fish Hatchery has finished spawning fall Chinooks this season, with 15,378,285 green salmon eggs taken/ “We have provided over 5 million of those eggs to the Coleman National Fish Hatchery,” she noted.

The Mokelumne River Fish Hatchery’s goal is to produce 8.9 million smolts (juvenile salmon) this coming spring. This includes 3.4 million for mitigation, 3 million for enhancement and 2.5 million for ‘climate resilience’ production.

Why is the Mokelumne seeing record runs of fish?

“There are lots of reasons that basically boil down to good communication and collaboration with DFW on overall management of this population,” said Workman. “Our hatchery incubation yields very high survival due to chillers and UV filters, our release strategies are very successful in yielding high survival to return, we had over 50,000 acre-feet of water for fall attraction this fall, and another year of a closed fishery left a lot of fish available for inland hatcheries and spawning grounds.”

“We continue maintaining suitable spawning habitat and flows in the river and have over 6,800 redds (salmon nests) in the river currently, so we are seeing success in both the hatchery production and in the river production,” explained Workman. “We are excited to see how the returns look 2-3 years out based on these record high runs!” 

Steelhead — anadromous rainbow trout — are also showing in large numbers on the Mokelumne. A new record for the number of steelhead returning to the Mokelumne River was set in February of this year when a total of 1,749 steelhead, including 968 adults and 781 fish under 18 inches, returned to the system.

The previous record for total steelhead was in 2018 when the hatchery reported 530 adults and 638 juveniles, a total of 1168 fish. However, there was another year when the total number of adults was over 700 fish.

The hatchery has already started spawning steelhead this season. The facility has reported 379 fish to date — and now is right in the middle of the run, according to Workman.

Regarding the record salmon run on the Mokelumne this year, Scott Artis, Executive Director of the Golden State Salmon Association (GSSA), stated, “This steps back to what we saw last year as well: that when we actually give fish the right water conditions or truck them past the Delta pumps, hot water and low flows, and give them a chance to survive, we see record returns despite all of the layers of bad salmon policy,” he said.

“Mokelumne River salmon are escaping all of Newsom’s bad water policies and are producing a record number of fish. That should tell us something,” he noted. 

“Whether the administration is Democratic or Republican, we need to make sure that at the end of the day we’re not killing tens of thousands of salmon jobs, entire coastal towns and cultures that rely on salmon,” Artis concluded.

Meanwhile, at the Coleman National Fishery on Battle Creek, a tributary of the Sacramento River below Redding, a low return of adults to Battle Creek has resulted in only 5.5 million eggs being collected this fall. As a result, the hatchery management requested and received millions of salmon eggs from multiple hatcheries operated by the California Department of Fish and Wildlife, including the Mokelumne River, Nimbus, and Feather River hatcheries.

Each year, Coleman NFH aims to release 12 million juvenile fall Chinook salmon.   

Spawning of fall-run Chinooks has been finished this year at the Feather River Hatchery and Nimbus Hatchery on the American River.

Upstream migrating fish totals through the Feather River Fish Monitoring Station between Jan. 1 and Nov. 24 (the latest date available) are:  

• Spring-run Chinook salmon (March 1 through June 30): 7,152
• Fall-run Chinook salmon (July 1 through present): 39,846          
• Steelhead: 1,710

“Annual Chinook salmon spawning activities at the Feather River Fish Hatchery in Oroville have been completed,” the California Department of Water Resources (DWR) reported in its Lake Oroville Update on Dec. 13: water.ca.gov/…

“The Hatchery collected enough eggs to meet its normal production goal of 2 million spring-run fingerlings and 6 million fall-run fingerlings, with additional eggs collected to increase production this year. Another 1 million spring-run and 6 million fall-run Chinook salmon will be produced to address declines in Central Valley Chinook salmon populations during recent years,” DWR wrote.

December 12 was the final date for salmon egg taking at Nimbus Fish Hatchery on the American River. “The ladder will continue running, but no more fish will be processed until steelhead are ready to begin spawning in a couple of weeks,” according to the hatchery’s Facebook page. 

The final numbers of salmon returning to the Central Valley rivers and fish hatcheries won’t be available to the public until late February and early March 2025, when all of the data is compiled for the Pacific Fishery Management Council’s meetings to craft the year’s salmon seasons.

However, it is important to note that the Mokelumne River is a tributary of the San Joaquin River, not the Sacramento River, and the ocean abundance estimates for the setting of ocean and river salmon fishing seasons are based on the Sacramento River Index.