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Locations: Feather River Fish Hatchery - Spawning Process

Lake Oroville
Feather River Fish Hatchery:
Spawning Process of Chinook salmon

The Feather River Fish Hatchery is run by the California Department of Fish and Game, and funded by the Department of Water Resources and the State Water Contractors, as part of the State Water Project.

Chinook salmon (Oncorhynchus tshawytscha) migrate by entering the Sacramento River from the Pacific Ocean, and then turning into the Feather River, the place of their birth. During this time, salmon don't eat, relying instead on their fat reserves for energy to propel themselves for the remainder of their journey in fresh water.

Once they reach the Feather River Fish Hatchery, the salmon enter a series of gates and fish ladders. The ladders are not unlike some of the natural river cascades they would encounter, if they were continuing upstream to complete their lifecycle.

Feather River Fish ladder
A Chinook going airborne as it swims up the fish ladder to the Feather River Fish Hatchery.

The ladder guides them into the spawning building, where they'll complete their life cycle and contribute to the next generation of Feather River Chinook salmon.

The fish are herded into a hydraulic lift. Those fish that are ready to spawn are quickly killed, sorted by sex, and sent down a two-sided table. It's on this table that the female's abdomen is opened up and the eggs are placed into a bucket. A male's abdomen is then squeezed over the eggs to release milt (sperm) to fertilize the eggs. Two females and two males are used per bucket.

Fish entering the spawning building
Fish entering the spawning building
A hydraulic lift readies the fish for sorting
A hydraulic lift readies the fish for sorting by DFG personnel
Males are sorted on the left and females are sorted on the right
Males are sorted on the left and females are sorted on the right.
The female's eggs are removed
The female's eggs are removed and put into a large bucket for mixing with the male's milt (sperm). Each female can produce 2,500 - 5,000 eggs.
milt is being mixed with the freshly harvested eggs
Here milt is being mixed with the freshly harvested eggs. Two female egg sacs and two male milts are used per bucket to provide genetic diversity
30 seconds for the eggs to become fertile
It only takes about 30 seconds for the eggs to become fertile. Then water is added to "water-harden" the eggs and prevent any late-stage fertlization.

From here, the eggs are carefully washed and placed in incubator trays, where a constant flow of fresh Feather River water flows through the eggs at all times. This provides a safe environment for their development, while protecting the eggs from the natural hazards of predation and flood. After several days, each tray is sorted and the unfertilized eggs are hand-picked and removed. Unfertilized eggs can be easily identified because they turn white. If left in the tray with the fertilized eggs, they will quickly collect mold and contaminate the fertilized eggs.

Incubation Trays
Incubation Trays simulate a safe but natural setting for eggs. Each tray holds up to 9,000 eggs.
eggs being monitored
These eggs are being monitored for their rates of successful Fertilization. Can you tell which eggs were not fertilized?

Counts are also done to determine the percentage of fertilized eggs versus unfertilized eggs. This ratio measures fecundity. An "eyed-egg" usually forms in 25 days and can be easily identified by the eyes within each egg. It only takes 45 days for a Chinook salmon to grow from a fertilized egg to an alevin (sac fry).

salmon eggs
25 days post-fertilization, eggs develop eyes and are called, "eyed-eggs."

Meanwhile, as with those salmon spawning in the river, the parents die and become food. The Department of Fish and Game, as do other States throughout the west, provides their salmon carcasses to worthy causes. In this case, these fish are on their way to a local food bank.

salmon for food banks
Click here for more information about the Feather River Fish Hatchery