Otolith output - Project to study alternative life history types of fall Chinook based on otoliths

This project describes ongoing work by scientists in FE Ecosystem Analysis and EFS Environmental Chemistry programs to identify natal and rearing locations, reconstruct life history strategy, and evaluate juvenile performance of adult Snake River fall Chinook salmon. Due to dramatic declines in its abundance, Snake River fall Chinook salmon was listed as threatened under the Endangered Species Act. Management of Snake River fall Chinook salmon has been hindered by a great deal of uncertainty regarding key aspects of the population. In particular, the existence of an overwintering behavior in a portion of the population has complicated estimates of survival through the hydropower system. Further, differential detectability of redds has limited the ability to accurately develop run reconstructions. Effective management of Snake River fall Chinook salmon will require an understanding of the details of their early life-history, including where juveniles hatch and rear, the proportion of juveniles that exhibit the yearling strategy, when they initiate downstream migration, and estuarine residence time. In this project we investigate early life history movement and performance of Snake River fall Chinook salmon by using microchemistry and microstructure of otoliths sampled from juveniles and adults. Results from this study are intended to help inform recovery planning including future habitat restoration and conservation efforts in the Snake River Basin and Columbia River.
Images, increment measurements, and microchemistry trajectories.