Sonoma Water staff conducts fisheries research and monitoring activities to support ongoing operations and Endangered Species Act compliance. Several of the more recent fisheries reports are summarized below.
Regardless of which portion of the Russian River young salmon and steelhead originate, all must travel downstream through the mainstem Russian River and estuary as they make their way to the ocean. Sonoma Water will monitor the effects that changes in river management related to the Russian River Biological Opinion have on salmon and steelhead populations over time by operating facilities designed to detect the movement of these fish out of tributaries and into the lower river. Follow-up efforts to capture fish that may reside for extended periods in the estuary will also provide information on growth.
Mirabel Rubber Dam/Wohler Pool Fish Sampling Program
This study evaluated the potential effects of the Mirabel Rubber Dam and Wohler Pool, a seasonal water supply reservoir, along the Russian River on Chinook salmon, steelhead and other native and non-native species. The study included video monitoring of the adult Chinook salmon migration in the fall, rotary screw trapping during the spring juvenile steelhead and Chinook salmon out migrating season, and electrofishing surveys of native and non-native fish populations in the summer.
The most asked question relating to this project is how many Chinook salmon spawn in the Russian each year. Annual counts of Chinook salmon have ranged from 1,125 to 6,103. These counts represent a minimum number of adult Chinook salmon passing the dam. During and after rainstorms, the river can become turbid and the visibility of the water is insufficient to observe fish migrating in front of the cameras. The cameras are installed by August 15th of each year, and are removed when the dam is deflated with the onset of heavy rainfall and high stream flows.
Radio-telemetry was used to study steelhead smolt passage through the Wohler Pool and inflatable dam on the mainstem Russian River. Transmitters were surgically implanted in hatchery smolts, and their movements were recorded. Radio tracking showed the percentage of fish that passed the dam site differed substantially before and after the river was impounded. We expanded the study to include a free-flowing control reach and released smolts 11 km above the dam. Travel rates and residence times in free-flowing (river) and impounded (reservoir) reaches were compared. Also, we compared flow characteristics and smolt responses to three dam configurations: full inflation, partial deflation, and partial deflation to create a notched effect.
Fall-Run Chinook Salmon Studies:
Chinook Salmon Spawning Study, Russian River
The purpose of this study is to determine the distribution and abundance of Chinook salmon spawning sites and compare results among years. Sonoma Water began conducting surveys in 2002 to address concerns that reduced water releases from Lake Mendocino may impact migrating and spawning Chinook salmon. Overall there has been a marked increase in the number of spawning Chinook salmon since the 1980s when Chinook salmon were considered nearly extirpated from the Russian River basin. Between 600 and over 1,100 redds have been reported annually in the upper Russian River.
Upper Russian River Steelhead Distribution Survey
This study evaluated the distribution of young steelhead during summer conditions and assessed habitat along the Russian River from Ukiah to Healdsburg in 2002. Rearing habitat for steelhead may be limited in the river when water temperatures are highest. The fish composition included 12 native and non-native fish species. A total of 1,436 steelhead were observed in the 37 sample sites. Steelhead were found primarily upstream of Cloverdale with observations as high as 265 steelhead/km.
“The Russian River Basin Steelhead and Coho Salmon Monitoring Program was designed to detect trends in salmonid populations and identify possible fisheries management and enhancement opportunities. The program began in fall 1999 with a pilot study to collect detailed information on the distribution, habitat use, and abundance of juvenile steelhead (Oncorhynchus mykiss) and coho salmon (O. kisutch) in streams of the Russian River basin. Electrofishing and snorkel surveys were used to sample fish in 5 tributaries of the Russian River.”