California’s remnant coho salmon populations are listed on the state and federal Endangered Species Acts and have been the focus of considerable investment in the form of population monitoring and restoration efforts. Water withdrawal for irrigation and widespread habitat alteration certainly contributed to the decline of coho salmon in the Shasta River, but the primary constraints on current population growth remain unknown. The scientists will use tagging surveys and – if proven effective – otolith signatures, to 1) Measure differences in juvenile coho life history from two different natal habitats in the Shasta River; 2) Characterize site use for fish with an early-emigrant life history that leave the Shasta River as young-of-the-year; and 3) Determine whether early emigrants that do not rear at the natal site as juveniles contribute to the population of returning adults. Results will contribute toward understanding population dynamics and identifying effective recovery actions for Shasta River coho salmon.