John Day River Sub-Yearling Spring Chinook Monitoring

Growth and survival of Alternative life history pathways of Juvenile Chinook Salmon in the upper John Day Basin

(Michael Scheu’s Thesis Research)

Recent studies indicate in the Upper John Day Basin greater numbers of sub-yearling Chinook salmon migrate early in their first summer of life to downstream nursery habitats than those that remain in the upper natal reaches. This early migrants seem to make up a majority of smolting yearlings in many years. There are many advantages for this life history to be favored by Chinook salmon in this river but it is the diversity of life histories what contributes to the stability and resilience of the population. Michael is investigating whether sub-yearling Chinook salmon that migrate early make up the largest proportion of their cohort. He is also characterizing what habitats these fish prefer and which ones offer better growth and survival conditions.