Winter-run king salmon numbers have reached critically low numbers on the Sacramento River. The Los Angeles Times published a detailed story today about the fishes’ struggles and how to fix things before it’s too late for salmon runs in the state. Here are a few details:
When Shasta Dam was built, the government also established Coleman National Fish Hatchery about 30 miles away. This hatchery raises millions of fish for release each year, including large numbers of fall-run Chinook that are caught and eaten.
But that operation failed to prevent major declines in the winter-run Chinook, which were listed as threatened in 1989 and declared endangered in 1994. To try to keep the winter-run population going, the government in 1997 opened Livingston Stone National Fish Hatchery at the base of Shasta Dam, where a steady stream of cold water flowed to its tanks.
If it weren’t for this hatchery, “there would be far fewer winter Chinook salmon,” said Brett Galyean, project leader for the U.S. Fish and Wildlife Service.
The adult fish swim to the base of Keswick Dam, where they are captured in a trap, loaded onto a truck and driven to the hatchery. Each winter-run Chinook is genetically tested and given a number, and each pair of male and female fish is selected. The spawning happens from May through the end of July. The tiny fish are raised until they’re large enough to be released in the Sacramento River.
Here’s more on winter-run kings from the California Department of Fish and Game:
In the early 1990’s the United States Bureau of Reclamation was required to build a Temperature Control Device (TCD) to manipulate the temperature of the water released from the Shasta Reservoir (Figures 1 and 2). This is a large structure situated on the inside face of the dam that allows water from different depths to pass through the hydro-power facility. Water is colder at greater depths through a phenomenon called stratification. The purpose of the TCD is to give State and Federal Agencies responsible for the conservation of SR winter-run Chinook Salmon the ability to control the water temperatures on the SR winter-run Chinook Salmon spawning grounds. The temperatures and the area covered by those temperatures are set each year for maximum survival of juvenile SR winter-run Chinook Salmon in the gravel and when newly emerged.
The amount of this cold water in Shasta Lake is limited however, and due to many factors, can run out. This is one of the greatest threats to naturally spawning SR winter-run Chinook salmon. If the “cold water pool” is not maintained at sufficient levels, there could be (and have been) catastrophic losses. California Department of Fish and Wildlife (CDFW) estimates that in 2014 and 2015 approximately 95% of the juvenile SR winter-run Chinook salmon production was lost when temperatures on the spawning grounds exceeded the goal of 56°F, after the cold-water pool was depleted. Conflicts can arise, especially during drought conditions, when cold water is needed for both water deliveries to various parts of California, in-Delta flows and the needs of SR winter-run Chinook salmon survival. This can be the largest human controlled factor for SR winter-run Chinook Salmon populations on the Sacramento River and in most years, it is maintained in favor of SR winter-run Chinook Salmon survival. In drought years or when lake water levels are low due to human demand, a lack of cold water can harm an entire year class of juvenile SR winter-run Chinook Salmon.