|RUSSIAN RIVER COHO SALMON CAPTIVE BROODSTOCK PROGRAM
The Central California Coast (CCC) Coho Salmon Evolutionary Significant Unit (ESU), ranging from the Lost Coast to Santa Cruz, is listed as endangered under both the state and federal Endangered Species Act. The Russian River watershed once harbored the largest coho population and is centrally located in the CCC ESU. Historically, over 30 streams in the watershed supported over 10,000 adult wild coho salmon. By 2001, only one stream in the watershed supported three consecutive year classes of coho – Green Valley Creek, with less than 100 adults estimated remaining.
In 2001, federal, state, and local government agencies, along with non-profit groups started the Russian River Coho Salmon Captive Broodstock Program – capturing the remaining offspring in the basin to preserve a genetic bank of the remnant population. Wild coho from nearby Marin County streams were added in 2007, which increased in-hatchery survival and genetic diversity. The goal of the program is to re-establish self-sustaining populations of coho salmon into streams within the Russian River watershed that historically supported coho. There are two program components: hatchery and monitoring.
Wild fish are captured from native streams, and integrated into the program with offspring from hatchery broodstock. At the Don Clausen Warm Springs Hatchery (WSH) hatchery, owned by the US Army Corps of Engineers (Corps) and jointly operated by the California Department of Fish and Wildlife (CDFW) broodstock are raised their entire lives in freshwater. Large, 20 feet-diameter, circular tanks allow for low rearing densities. Krill, a natural food source, is fed to the fish to help promote proper growth and development to adults. DNA samples taken from each fish allow geneticists to create an annual breeding matrix to prevent inbreeding and maximize genetic variation for each spawning population.
Progeny are marked or tagged prior to release into 20 different historic streams within the watershed at three different life-stages: fingerling, advance-fingerling, and smolt. Fingerlings and advanced fingerlings are released during the spring and fall. Using water-filled backpacks fitted with aerators, crews hike the creeks releasing the fish at low-densities into the best available habitat. Smolts are imprinted in streamside acclimation tanks for 2-4 weeks prior to being release. The goal is for all of the juvenile coho to return to their release streams as adults to spawn on their own thereby allowing natural mate selection.
Over 11 spawning cycles, more than 1 million juvenile coho have been reared and released. Monitoring is a key program component, and occurs throughout the year. University Cooperative Extension-Sea Grant coordinates the monitoring program, and works with the Sonoma County Water Agency to trap, survey and county coho at various life stages. In the summer of 2011, monitoring revealed wild spawned juvenile coho in 19 out of the 23 streams they surveyed. During the winter of 2011-12 and 2012-13 monitoring estimated 400 and 530 adult coho returns, the most observed in over a decade. Although the number of adult returns decreased during the following two winters due to the ongoing drought, wild spawned juvenile coho continue to be found in numerous tributaries throughout the Russian River watershed.
Though originally intended to service the Russian Sonoma County population, WSH now also rears small numbers of Olema and Redwood Creek (Marin County) coho and Scott Creek (Santa Cruz County) coho, with excess broodstock released into smaller nearby barren watersheds which historically were ‘dependent’ upon the larger basins with more robust populations for colonization by straying.
Scott Creek coho are being reared at WSH to produce high-quality coho broodstock for the MBSTP/NOAA Fisheries recovery hatchery program in Santa Cruz. The rearing of Redwood Creek coho are funded through an MOU with the National Park Service and the Corps. Expansion into Mendocino County streams, the northern portion of the ESU where coho have declined more recently, is expected in 2016 through completion of a Hatchery Genetic Management Plan with support from the NMFS and CDFW on this ‘regional’ strategy.
Future and Current Challenges
The program currently raises and releases up to 250,000 offspring annually. Equally importantly, the program has developed the technical and biological expertise to implement the requirements of the only recovery hatchery north of the SF Bay, including conservation reared broodstock and offspring through genetically optimal mating protocols.
Capacity to operate as a regional facility is limited in the short term by needs of additional filtration, and chilling for the drought affected water supply. Additional incubation stacks, adult rearing and spawning space is also needed for a rearing population of 500,000 to fully implement the regional strategy to assist recovery for the northern CCC ESU Coho.