(Update) December 2016
The Redwood Creek Coho Salmon Captive Rearing Project is in its third year.
2016 Juvenile Collections
- BY14 collected in 2015: 200
- BY15 collected in 2016: 202
2016 Adult Releases
- Total: 106
- Females:69 BY12 (56 mature, 13 immature)
- Males: 34 BY12 (32 mature, 2 immature)
- Males: 3 BY14 jacks
Figure 1: CDFW and ACOE staff net Coho Salmon from the hatchery tank.
On December 9, 2016, CDFW transported adult Coho Salmon from Warm Springs Hatchery to Redwood Creek, Marin County (Figure 1). A total of 106 hatchery reared, natural origin adult Coho Salmon were released into their natal creek to spawn. This marked the completion of captive rearing of the first cohort or broodyear (BY12) of Coho Salmon collected from Redwood Creek in 2014 (see full story below). The remaining two cohorts, that were collected in the summer of 2015 and 2016 are currently being reared at Warm Springs Hatchery, Lake Sonoma.
The timing of the release was near perfect with water rising and more rain in the immediate forecast (Figure 2). All released Coho Salmon were of Redwood Creek origin. With the exception of three BY14 jacks (2-year olds), all released fish were presumably BY12 (4-year olds).
Coho Salmon previously tagged with Passive Integrated Transponders (PIT) were scanned with a hand-held reader prior to release and the number and release site recorded (Figure 3). PIT tags are used to monitor spawning distribution. Colored floy tags are also used for easy identification of live fish.. The National Parks Service and Point Reyes National Seashore Association will conduct spawner and redd surveys this winter, and juvenile monitoing is planned for the summer to estimate spawning success.
Figure 2: Agency folks and friends gather to watch Coho Salmon released to their natal creek to spawn.
Figure 3: Biologists used a hand-held PIT reader to identify previously tagged Coho Salmon prior to release.
(Update) October 2015
The Redwood Creek Coho Salmon Captive Rearing Project is in its second year.
- 2014 Brood Year 2012 (BY12): 129 collected, 115 remaining
- 2015 (BY14): 200 collected, 193 remaining
- 2016 (BY15): 200 (planned)
Planned Adult Releases
- Winter 2015: 3 mature males (BY12)
- Winter 2016: 112 mature coho (BY12)
- Winter 2017: 193 mature coho (BY14)
- Winter 2018: 200 mature coho (BY15) (not yet collected)
All incoming juvenile coho salmon were placed in quarantine at Warm Springs Hatchery (WSH), also known as Don Clausen Fish Hatchery (DCFH) on Lake Sonoma, and treated with oxytetracycline and formalin to prevent bacterial and fungal infections. Fish food consists of a combination of fry feed and natural krill. An inventory of BY12 conducted in late September 2015 showed that most coho salmon in this group measured 290 mm (almost 12 inches) mean length and a mean weight of 380 g (over ¾ lb.). A few fish in this group were significantly smaller. Ultrasound (Figure 1) was the method used to determine if fish were mature, and examination revealed that only three of these coho salmon had visible gonads (all males). As an example, figure 2 shows the ultrasound image of a mature female from the Warm Springs 2007 broodstock.
Figure 1: Program lead, Ben White (ACOE) examines adult coho salmon using ultrasound.
Figure 2: January 2011 ultrasound image of female coho salmon (BY 2007) showing hydrated eggs.
Facts and Highlights
Necessity of Project
The prolonged severe drought and past poor ocean rearing conditions in California are placing many endangered coho salmon populations at increased risk of extinction throughout the central coast. Recent annual adult coho abundance in Redwood Creek is below 10 individuals in two brood-years and below 50 in the third brood-year. Juvenile coho abundance in 2014 is estimated below 200. Without captive rearing, there is a high risk that Redwood Creek coho will completely disappear in the very near future.
To prevent extirpation of the three brood-years of coho salmon in Redwood Creek, temporarily increase spawner abundance, and preserve the remaining genotypes of the population.
Planned Coho Collections
Up to 300 juveniles in summer 2014, 2015, 2016. Initial collection date: Aug. 13, 2014.
Warm Springs Hatchery, also known as Don Clausen Fish Hatchery at Lake Sonoma.
Genetically analyze captured fish and rear in freshwater for up to three years.
Planned Coho Releases
Release as mature adults in winter of 2016, 2017, 2018.
Initial Duration and Size of Project
Five years and up to 300 fish authorized (capture, rearing and release of three consecutive brood-years plus monitoring, 2014-2019).
California Department of Fish and Wildlife (CDFW), NOAA National Marine Fisheries Service (NMFS), Army Corps of Engineers (ACOE), California Department of Parks and Recreation (CDPR), Golden Gate National Recreation Area - National Parks Service (GGNRA-NPS).
NMFS’ Section10(a)1(A) permits issued to the Russian River Coho Salmon Captive Broodstock Program; NPS and CDPR research and collecting permit; Interagency Fish Rescue Policy (CDFW/NMFS/USFWS). Fish rescue by CDFW is exempt under CEQA.