Survival and Movement of Juvenile Coho Salmon (Oncorhynchus kisutch) in the Shasta River, California

Movement and survival of PIT tagged juvenile coho salmon (Oncorhynchus kisutch) were assessed using a network of detection stations located throughout the Shasta River, a tributary of the Klamath River in interior northern California. This highly productive river system promotes rapid growth rates of salmonids. Coho salmon are large enough to PIT tag during their first spring, allowing detailed information on movements and survival to be collected, from approximately three months after emergence to age-1 smolt outmigration. The general movement patterns observed were outmigration of age-0 coho salmon from the Shasta River at both fry and smolt life stages, extensive upstream movements to summer rearing locations, fall redistribution among segments of the watershed, and smolt outmigration at age-1 during the second spring. I developed a multi-state mark-recapture model to estimate apparent survival, movement, and detection probabilities among four segments of the Shasta River during the first spring, summer, winter, and age-1 smolt outmigration periods. Apparent survival estimates in different segments of the Shasta River ranged from 0.42 to 0.74 over the summer and from 0.52 to 1.00 over the winter. The estimated apparent survival probability for age-1 smolts migrating from the upper Shasta River to the Klamath River was 0.77.Findings in this study may be used to guide restoration efforts for coho salmon in the Shasta River by focusing them on locations that are not meeting fish needs or during seasonal periods of low survival.