Spring Chinook Salmon
Spring Chinook are not native to the Wind River. Shippard Falls three miles upstream blocked their passage until a fish ladder was built in 1955. But the location is ideal for a hatchery. Adult salmon have only one dam to negotiate, and as a result, Carson has one of the highest return rates of any hatchery.
Carson's ponds and incubation buildings are fed by pollution-free Tyee Spring, which stays at a constant 44 degreesperfect for incubating salmon eggs. When they return as adults each May and June, they follow the scent right up the fish ladder and into the hatchery's holding ponds. Here they stay until they are ready to spawn.
Once they arrive at the hatchery, adult salmon take 3 to 4 months to attain spawning condition. Periodically the fish are checked to see if they are "ripe" (ready to spawn). They are also inoculated for bacterial kidney disease, which can be transmitted from adults to eggs.
When most of the fish are ripe, they are crowded into the spawning area. Ripe fish are quickly killed to facilitate handling; "green" fish are sent back to the holding pond. Females are then cut open to release their eggs. Milt, stripped from a male, is mixed with the eggs to fertilize them.
At the hatchery building, eggs are washed, disinfected, and poured into incubation buckets. Cold, well-aerated water flowing through the buckets mimics a stream environment. After 80 days eggs hatch into sac fry, eel-like creatures about an inch long, with sacs of egg yolk attached to their bellies. They stay in incubation trays for 10 weeks, until they use up the yolk.
Hungry now, the young salmon, now called fry, instinctively swim upwards in search of food. They are transferred to outdoor raceways and fed a nutritious diet containing fish and grain meal, plus vitamins and minerals. Some of the fry are raised in earthen ponds rather than raceways. These are more similar to a natural environment.
When fry are 18 months old and about 6 inches long, they smolt: tails lengthen and become more deeply forked, juvenile spots disappear, and the urge to migrate begins. In April, Carson's smolts are released into the Wind River. They swim downstream to estuaries at the mouth of the Columbia River. They stay there for several weeks, feeding voraciously and adjusting to salt water.