Playing Cupid to Help Coho Salmon

The redwood forests of California’s North Coast are known for their raw beauty and rich wildlife. But decades of aggressive timber harvesting combined with overfishing, changing timber owners and encroaching development for housing and agriculture left this landscape diminished, with heavy impacts on the watershed and the species that call it home—like coho salmon, a federally and state protected species.

Fish can’t go forth and multiply without healthy watersheds. Within the 74,000 acres of our North Coast Forest Conservation Initiative, we’ve spent years enhancing habitat in the Garcia River watershed through sediment reduction activity such as improving roads and changing timber harvesting methods which have less impact on the landscape. We are also improving in stream habitat by leaving more trees in riparian area and adding large wood for cover, which helps to recruit and restore spawning gravels in our streams. We have created a near natural ecosystem and conditions for easier passage and safer refuge for the fish to spawn. Yet, the numbers of returning adult coho were below the threshold for a viable population to maintain itself over multiple years. There have been so few salmon returning to a stream that they are unable to find a mate.

_{Can you believe that in just 3 years this tiny juvenile coho salmon will grow into a mature fish measuring 19 pounds or more? Photo by Nick Bauer/California Sea Grant.}

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.

_{Partners get ready to capture salmon in the Garcia River in 2018. Photo by Jennifer Carah, The Nature Conservancy.}

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 juvenile coho salmon collected in the Garcia and Navarro Rivers for the genotyping project were weighed, measured, and electronically tagged—here by Benjamin White, Supervisory Fish Biologist with the U.S. Army Corps of Engineers—so they could be tracked throughout their time in the hatchery. Photo by Heather Gately, The Nature Conservancy.}

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.

_{Blake Tallman, Forest Technician for The Conservation Fund, is pictured releasing an adult coho salmon back into the Garcia River as part of a multi-year broodstock program. Photo by Jennifer Carah, The Nature Conservancy.}

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.”