Cryopreservation for Chinook Salmon and Steelhead Trout Sperm

May 2, 2025

For the past four years, the California Department of Fish and Wildlife (CDFW) has been working to develop cryopreservation techniques for salmon and steelhead sperm to capture the genetic diversity of these fish in their current state. Maintaining sperm from current generations of fish can be important for long term fisheries conservation. Unforeseen disasters and climate change impacts can result in declining population sizes, and this allows fisheries managers to add genetic diversity back into the population, if needed. Cryopreservation is not new and has been used for decades in animal farming and in places like the San Diego Zoo for important species conservation. CDFW keeps this salmonid sperm in a laboratory suspended in liquid nitrogen where it can last for decades, theoretically forever, if kept in its static, frozen condition. This year, CDFW research scientists and hatchery staff successfully fertilized Chinook salmon eggs with sperm frozen from the previous year. Watch this video to learn more.