Returning Coho Salmon
Scientists working on the recovery of endangered coho salmon in northern California appreciate success even if it comes in small doses. Field biologists from the California Department of Fish and Game (DFG) recently reported the largest number of coho returning to spawn in Sonoma County tributaries of the Russian River in more than a decade.
"Most of these fish were released as fingerlings into the river system, as part of a captive broodstock program at Don Clausen Warm Springs Hatchery on Lake Sonoma. The broodstock program began 10 years ago, when wild coho salmon were rapidly vanishing from the region."
Prior to the launch of the recovery program in 2001, the number of returning adult coho salmon averaged less than four per year. These low numbers were the catalyst for the Russian River Coho Salmon Captive Broodstock Program, a recovery effort in which offspring from hatchery-reared adults are released into the river system.
This year, biologists estimate that more than 190 adult coho may have returned to the Russian River system, beginning with early storms in October and peaking in December. Promisingly, a few coho are being sighted in creeks that are not stocked, utilizing habitat beyond those tributaries in which coho are released.
"We are hopeful that coho salmon released through this program will continue to return to the Russian River system in increasing numbers and begin to establish self-sustaining populations," says Manfred Kittel, Coho Salmon Recovery Coordinator for DFG's Bay Delta Region. "The program is a cornerstone of coho salmon recovery efforts in central California, but the number of fish observed this year must be seen in perspective. A healthy coho population should number in the tens of thousands in California."
Coho salmon abundance has declined dramatically statewide in the past few years. Biologists believe that additional captive breeding efforts and other focused recovery measures will likely have to be instituted to prevent widespread extinction of coho salmon in central California.
The Russian River Coho Salmon Captive Broodstock Program is a broad coalition of government agencies, scientists and private landowners dedicated to bringing back productive salmon runs. Its members include DFG, which manages the hatchery component at the Don Clausen Warm Springs Hatchery, University of California Sea Grant Extension, National Marine Fisheries Service, U.S. Army Corp of Engineers and Sonoma County Water Agency.
COHO SALMON (Oncorhynchus kisutch)
Common Names: Coho salmon, coho, silver salmon, blueback, sea trout
Preferred Temperature: 14 ºC
Range: 54‐57 ºF
Weight: 4-11 pounds
Length: 11-26 inches
Predators for Sea Lamprey, humans Larger carnivorous fish, birds, and mammals
Identification: Adults are steel‐blue to slightly green on the back, brilliant silver on the sides, and white on the belly. There are small black spots on the back, sides above the lateral line, base of the dorsal fin, and upper half of the caudal fin.
Coho differ from the Chinook and other salmonids of the Great Lakes by having the inside of their teeth set in white gums, their tail slightly forked with spots on the top half, and having 12-15 rays in their anal fin.
Distribution: Native to the Pacific Coast from southern California to northern Alaska and in Asia south to Japan. Attempts to establish coho salmon in the Great Lakes date back to 1873. These efforts met with little or no success until 1966, when Michigan began planting large numbers of coho. Coho salmon are now found in all the Great Lakes. In the Wisconsin waters of Lake Michigan, coho salmon are found from Kenosha north to Sturgeon Bay.