Due to drought and poor water conditions at Lake Sonoma, thousands of juvenile coho salmon have been relocated from the Warm Springs Fish Hatchery in Geyserville. The fish were trucked to a conservation facility at a high school in Petaluma where they will be reared until conditions improve.
Beginning in late spring, rising water temperatures at Warm Springs Hatchery increased the risk of heat stress and pathogen outbreaks. Scientists developed the relocation plan as a precaution to keep the hatchery coho safe.
“We all have a vested interest in seeing coho salmon remain healthy. In addition to being endangered, coho are an indicator species and a sign of the health of the watershed. When they’re in danger action needs to be taken,” said CDFW Acting Regional Manager Stacy Sherman.
The relocation was made possible by a successful public private partnership led by the U.S. Army Corps of Engineers (USACE), which operates the Warm Springs Fish Hatchery. The California Department of Fish and Wildlife (CDFW) contributed pathogen testing and logistical support. The student-operated conservation facility, located at Casa Grande High School in Petaluma, is maintained by United Anglers of Casa Grande, Inc. Also joining the relocation effort was the National Marine Fisheries Service, and Monterey Bay Salmon and Trout Project, Sonoma Water and Jackson Family Wines which provided funding for the effort.
Coho kept as hatchery broodstock are carefully managed so that their genetic diversity is comparable with wild populations of the Central California Coast Evolutionarily Significant Unit. With wild populations facing poor river conditions due to drought, captive fish act as insurance against loss of genetic diversity.
“Relocating a portion of the juvenile coho provides additional protection for the maintenance of genetic diversity, which is important for resilience of the species as a whole,” said Sherman.
The relocation effort was carried out during July and August 2021. In total, about 4,000 juvenile coho were relocated from Warm Springs Hatchery to the conservation facility at Casa Grande High School.