April 11, 2022 — When Shasta Dam was built on the Sacramento River in the 1940s, the government also established Coleman National Fish Hatchery about 30 miles away on the tributary Battle Creek, aiming to make up for the loss of upstream habitat by raising fish for release.
The hatchery’s staff runs an elaborate spawning operation that this year is raising 12 million fall-run Chinook salmon, supporting California’s commercial and recreational fisheries. The hatchery also raises other types of salmon and steelhead.
The adult salmon swim up the Sacramento River and into Battle Creek, then up a fish ladder to the hatchery’s holding ponds. Mechanical screens in the water are used to move the fish to the spawning building.
The fish are placed into a bath with carbon-dioxide in the water, which enables the staff to handle them. Workers lift the salmon from the water in nets, check to see that they’re ready for spawning, and separate females from males.
They club the fish and send them sliding down a metal chute. One worker hangs each female salmon from a hook, inserts a needle in its abdomen and sends air flowing to push out the eggs, which land in a colander. Another worker grabs each male fish and twists the tail, squeezing out milt that will fertilize the eggs.