Nimbus Fish Hatchery

The Nimbus Fish Hatchery is located in eastern Sacramento County, built on the left side of the Nimbus Dam.^[1] It is one of the 21 fish hatcheries the California Department of Fish and Wildlife oversees.^[2] Chinook salmon and steelhead are raised, and about 4 million Chinook salmon and 430,000 steelhead released each year.^[3]

History

Salmon once spawned up and down the rivers of California, but with more human infrastructure came more habitat change. Upstream rivers have been damned to for lakes or water reservoirs. This has greatly diminished the availability of space appropriate habitat for the fish to spawn and live in. The regional salmon used to migrate up the American riven to mountain lakes and now the hatchery is the end of their journey for many. The hatchery is located along the American River in East Sacramento. The Nimbus Dam cut off historic salmon runs, so in return an artificial system was established. In 1958, the Nimbus hatchery was established. This Hatchery was established to mitigate the impacts the Folsom and Nimbus dams have on the American River flow.^[4] The dam holds sediment and gravels, which cause for a change in river habitat. The gravels needed for historic spawning grounds in leading Salmon to look elsewhere to lay their hatch.

Nimbus hatchery programs

The hatchery is operated by California Fish and Wildlife. The purpose is to manage the natural species populations. The hatchery allows to sustain species, and give the opportunity for habitat restoration in the process. Each year to maintain species abundance of steelhead and salmon, over 50 million juveniles are raised in hatcheries and then released to complete their journey down the river.^[5] These are funded by the U.S. Congress. These programs are focused on seasonal steelhead, Chinook, and Coho salmon and their harvest and species conservation measures. Anadromous Fish hatchers like the Nimbus Hatchery are designed to have minimal impact on natural fish populations.

Spawning habitat

Wild salmon look for a specific spawning habitat. The size of the gravel influences the survival of their young. The dams upstream on Folsom impact salmon spawning. Salmon require 7ppm of oxygen to survive in waters. During development small salmon need side pools on the river to get rest in the cool shade and to hide from predators. Salmon eggs are said to need 2-30 centimeters deep water, where drys need anywhere between 20-40 centimeters of water. Salmon need a pH between 6.5 and 8 in waters between 5-8 °C. Thick vegetation along the waters edge provides shade to keep the water cool enough to survive in warmer months. Many spawning habitats have been destroyed or are threatened. Because of this, the fish hatchery programs have been put in place to sustain fish populations.^[6]

Impacts on salmon and steelhead=

• Number of fish released annually: Salmon (4 million) Steelhead (430,000)
• Number of fish spawned (average): Salmon (2,600) Steelhead (200)
• Number of eggs taken: Salmon (6 million) Steelhead (1-2 million)
• Average number of eggs per female: Salmon (5,200) Steelhead(5,600)
• Average weight at spawning: Salmon(15-35 lbs) Steelhead(6-10 lbs)
• Record weight: Salmon-138 lbs (Alaska) 107 lbs (California) 62.5 lbs (Nimbus) Steelhead-42 lbs (Alaska) 23 lbs (California) 20 lbs (Nimbus)
• Incubation time: Salmon (45 days) Steelhead (35 days)
• Spawning season: Salmon (Oct.- Dec.) Steelhead (Jan. –Mar.)

Figure2. At the Hatchery, one can see the early life stages the salmon undergo while staying at the Hatchery.

Hatchery structure

Figure3. These structures in the middle of the river are in pace to have the fish during each of the seasonal runs move up the salmon ladder into the hatchery.

The hatchery is part of a greater interconnected network within the region. The dams upstream from the hatchery control irrigation, generate power, supply water, and are a main source of flood control.^[7] As shown in figure 3, there are rocks guiding the salmon in the direction of the ladder to enter the hatchery. The ladder brings them up to harvest and spawning tanks. From here they harvest from the adult salmon and fertilize the eggs. There are separate holding tanks for each species, whether it be Chinook salmon, steelhead, and rainbow trout.They move down the holding tanks the greater they grow in size. The holding tanks are to simulate the natural river flow. The fish jump up the flow to move between tanks. After the fish grow to between four and six inches to where they are able to survive on their own, they are carried in tanks to further down the river. From here they are taken down stream so, they are able to journey out to sea.^[8] The hatchery is there to provide adequate space, afterflows, and temperature regimes.^[9]

Contributions

Each year the hatchery raises around 4 million baby salmon. Fish are grown to about 4-6 inches in length at the hatchery, and then they are released into the Sacramento River.^[10] These are grown and released back into the delta. Integrated hatchery programs increase the abundance of species, but are able to minimize genetic divergence in the maintenance of fish populations.^[11] The creation of the Nimbus Hatchery has mitigated for impacts on the steelhead and salmon populations. To measure impacts, the salmon are clipped with a fin clip for analysis if movement, and survival.^[12]

Related links

• California Hatchery Program
• Hatchery Review
• California Salmon Spawning^[13]

References

1. "Recreation.gov recreation area details - Nimbus Fish Hatchery - Recreation.gov". www.recreation.gov. Retrieved 2016-03-02.
2. "CDFW Fish Hatcheries". www.wildlife.ca.gov. Retrieved 2016-03-02.
3. California Department of Fish and Wildlife. "Why a Hatchery?". p. 2. Retrieved 2016-03-02.
4. https://www.wildlife.ca.gov/Fishing/Hatcheries/Nimbus/History
5. http://cahatcheryreview.com/wp-content/uploads/2012/08/CA%20Hatchery%20Review%20Report%20Final%207-31-12.pdf#page=83
6. (PDF) http://www.pac.dfo-mpo.gc.ca/education/documents/sicinter-secinter/sic_intermediate_unithandouts_3.pdf. Missing or empty |title= (help)
7. https://www.wildlife.ca.gov/Fishing/Hatcheries/Nimbus/History
8. http://cahatcheryreview.com/wp-content/uploads/2012/08/CA%20Hatchery%20Review%20Report%20Final%207-31-12.pdf#page=82/
9. http://cahatcheryreview.com/wp-content/uploads/2012/08/CA%20Hatchery%20Review%20Report%20Final%207-31-12.pdf#page=82
10. http://www.visitfolsom.com/history/nimbus_hatchery.aspx>
11. "California Hatchery ReviewReport" (PDF). California Hatchery Review. U.S Fish and WildlifeService and Pacific States Marine Fisheries Commission.
12. https://www.wildlife.ca.gov/Fishing/Hatcheries/Nimbus/History
13. "California Hatchery Review Report" (PDF). California Hatchery Review. U.S Fish and WildlifeService and Pacific States Marine Fisheries Commission.