Approximately 750,000 late-fall Chinook salmon will be released into Battle Creek Jan. 13-14, 2014, the U.S. Fish and Wildlife Service announced today. The Coleman National Fish Hatchery (NFH) in Anderson, Calif. produces approximately 1 million late-fall Chinook salmon juveniles each year. About 250,000 were released at the hatchery in early December 2013.
Late-fall Chinook salmon eggs are collected at Coleman NFH from returning adults. The juveniles then are raised at the hatchery for about one year and typically are released from December through early January. The fish are released on site into Battle Creek, a cold-water tributary of the Sacramento River, so they complete the imprinting cycle during their out-migration to the ocean.
This release strategy increases the likelihood these fish will return to the upper Sacramento River as adults to contribute to the in-river fishery and return to the hatchery in sufficient numbers to perpetuate runs and ensure continuity of collecting, spawning and rearing activities for important Chinook salmon propagation programs. This on-site release practice for late-fall Chinook salmon also is consistent with the best science available and the standards and guidelines for releases of salmon in the Central Valley of California put forward in the California Hatchery Scientific Review Group Report (2012).
Releases generally are timed to coincide with periods of rainfall, which increases flow and turbidity of rivers, enhancing survival of the fish as they make their way to the ocean. However, a record dry year in California delayed this year’s release of late-fall Chinook.
In previous years, the Service experimented with trucking juvenile fall-run Chinook to the Sacramento River Delta for release in San Pablo Bay. However, science now shows that although trucking young salmon downstream can improve overall survival, the process interferes with the imprinting cycle, causing adult salmon to “stray” instead of returning to their river area or stream/creek of origin.
“In the case of the Coleman fall Chinook salmon that were trucked to the Delta, straying was excessive, and there was almost a complete lack of returning fish from the trucked groups back to the hatchery,” said Scott Hamelberg, project leader at Coleman NFH Complex. Similarly for late-fall Chinook salmon, disrupting the imprinting cycle by trucking the fish to some downstream location will promote straying. Straying has high potential to: 1) result in fewer fish returning to Battle Creek for future broodstock use, 2) impact the upper Sacramento in-river fishery for late-fall Chinook salmon if they do not ascend high enough up the Sacramento River, and 3) result in ecological or genetic impacts or loss of returning adults through the return of adult late-fall fall Chinook salmon to areas not normally known to support late-fall Chinook salmon.
Four distinct runs of Chinook salmon spawn in the Sacramento-San Joaquin River system, named for the season when the majority of the run enters freshwater as adults: fall, late-fall, winter and spring. Fall and late-fall Chinook salmon and steelhead are propagated at Coleman NFH. Winter Chinook, an endangered species, are propagated at Livingston Stone NFH near Shasta Dam. Late-fall Chinook are found mostly in the Sacramento River between the Red Bluff Diversion Dam and Keswick Dam. Although not a species listed under the Endangered Species Act, late-fall Chinook are a species of concern due to limited range and population size.
Coleman NFH was constructed in 1942 as part of the mitigation measures to help preserve significant runs of Chinook salmon threatened by the loss of natural spawning areas resulting from the construction of Shasta and Keswick dams on the upper Sacramento River. Situated on Battle Creek near Anderson, Calif., the hatchery produces 12 million fall Chinook salmon, 1 million late-fall Chinook salmon, and 600,000 steelhead trout annually.
Logo courtesy U.S. Fish and Wildlife Service