Playing Cupid to Help Coho Salmon

Looking for another strategy to keep coho salmon populations from becoming locally extinct, we teamed up with the U.S. Army Corps of Engineers, the National Oceanic and Atmospheric Administration (NOAA) Fisheries, California Department of Fish and Wildlife (CDFW), North Coast Regional Water Quality Control Board, The Nature Conservancy, and the Mendocino Redwood Company and co-sponsored a multi-year capture, rearing and release program.

In 2018, young fish were collected from The Conservation Fund’s property on the Garcia River and the nearby Navarro River and transported to a nearby hatchery, where scientists tagged, genotyped and created a genetic breeding matrix for each fish—a scientific spreadsheet that identifies compatible mating pairs based on each fish’s genetic makeup.

The coho were raised to adulthood, and pods of the least related groups were released back into the rivers to spawn at the end of 2020. This approach to genetic matchmaking—mirroring a similar effort in the Russian River watershed, in Sonoma County, in the early 2000s—is designed to supplement the natural coho salmon populations in the rivers, minimize further erosion of genetic variability for the species, and hopefully boost population numbers. Since the recent release, scientists have been thrilled to observe the coho salmon from the program mating with each other and with salmon returning from the ocean.

Over the next few years, the public agency and NGO partners will assess the success of the program by monitoring the next generation of juveniles, gathering genetic samples to figure out who their parents are, and counting salmon nests. The partnership will adapt the program based on lessons learned this first release year.

As Bob Coey, North Coast Branch Chief with NOAA Fisheries West Coast Region in Santa Rosa, says: “Fish first! We have to do what we can to give coho salmon the best chance to find some romance in growing these populations.”