This season’s surprisingly higher return of coho salmon to the Scott River is generating lots of local excitement. At least 340 adult coho are documented, as of December 8th, at the Scott River weir. This number represents a significant increase over the 62 fish counted when this brood year last returned 3 years ago in 2008.
"The California Department of Fish and Game is encouraged by the preliminary 2011 adult coho returns to the Scott River indicating an increase in adult coho salmon abundance," commented Morgan Knechtle, an associate fisheries biologist with CDFG in Yreka. Knechtle operates the department’s video weir where the fish data are collected, located 18 miles upstream from the mouth of the Scott River.
Habitat restoration efforts are one of the reasons for the better numbers, says Gary Black, contractor and former senior project manager with the Siskiyou Resource Conservation District (RCD). “The Scott Valley community should be proud of the unexpectedly higher coho return because measures taken by its residents have helped the stream habitat in the Scott River and tributaries to become much better than it was 10-15 years ago. The facts tell us the Scott River is a good and improving stream for fisheries.”
Ocean conditions also play a role in salmon population cycles. Coho salmon tend to return in three-year cycles, hence the comparison between the 2008 and 2011 runs. Biologists had predicted a much lower return of about 37 fish for this low brood year, based on the average past survival rate of yearling coho leaving the Scott River and returning as adults. The Scott River has one stronger brood year and two weaker ones. The stronger brood year was in 2010 with 927 coho returning and again in 2007 when 1,622 returned.
The annual survey of coho spawning grounds in the mainstem Scott River and tributaries is also ongoing to identify where the redds (nests) and carcasses are found. In Scott Valley, the Siskiyou RCD staff is leading the survey where access is available, while CDFG is coordinating the effort in the canyon area. [See attached photo.] This information will help the Scott River Water Trust identify where the young coho salmon may need additional water next summer to ensure better survival. As a win-win tool for fish and farmers, the Water Trust will pay for water to be left instream.
An estimated 2,174 yearlings migrated out of the river for this brood year in the spring of 2010, representing 34.5 yearlings produced per adult, according to Fish & Game data. This freshwater survival rate appears to be an indicator of in-river conditions. In contrast, the out-of-basin survival rate may indicate downriver and ocean conditions. Until this year, that rate had averaged 1.74 percent yearlings to survive as returning adults.
Coho salmon in the Klamath River Basin were listed as a threatened species in 1997 under the federal Endangered Species Act (ESA) and in 2005 under the California ESA. Before and after those listings, the Scott Valley community has actively participated in voluntary watershed and stream restoration efforts. More restrictive regulatory programs by state and federal agencies were also proposed. Expectations are for increased population trends of all three coho brood years.
Tuesday, December 20, 2011
Scott River coho making a comeback
From the Scott River Water Trust, which provided the photo: