Presentation on theme: "Examining the effects of juvenile migration timing, hydropower- system passage type, and environmental factors on adult age- at-return of Snake River salmon."— Presentation transcript:
Examining the effects of juvenile migration timing, hydropower- system passage type, and environmental factors on adult age- at-return of Snake River salmon Benjamin P. Sandford*, Eric R. Buhle, Jennifer L. Gosselin, and Mark D. Scheuerell Fish Ecology Division Fish Ecology Division Northwest Fisheries Science Center NOAA Fisheries Service
Introduction The Columbia/Snake River System has been extensively altered with hydropower and water- storage dams. This has significantly altered salmon migration timing patterns for many reasons. Understanding the effects of these changes is important for making future management actions.
Objectives Characterize the relationship between ocean- age and various juvenile migration and estuary/ocean factors for Chinook salmon –Rearing Type (analyzed separately, wild/natural only here) –Juvenile length –Lower Granite release date, flow, temperature –Barge transport or In-river migration –Ocean indicators: CUI, PDO, NPGO, ONI, PNI –Migration year (time series nuisance factor)
A Hierarchical Model of Adult Age log ratio transform Data Model observed age is multinomially distributed Process Model cohort + individual-level components cohort level: covariates, process error with auto- and cross-correlation individual level: may include covariates, but no additional process error
A Hierarchical Model of Adult Age Hierarchical Bayesian estimation in R/JAGS Model selection (all models include auto- and cross-correlation): 1)no covariates 2)cohort-level covariates only Apr-May CUI, Mar-Aug PDO, Mar-Aug NPGO, annual ONI, annual PNI 3)individual-level covariates only transport (I/T), length, release day, LGR discharge, LGR temp 4)cohort + individual covariates Compare candidate models by deviance information criterion (DIC)
Summary Ocean-age of PIT-tagged wild spring/summer Chinook salmon from the Snake/Columbia River had the following characteristics: In-river migrating juveniles returned as older adults than barge- transported fish Larger juveniles returned as younger adults Earlier-migrating juveniles returned as younger adults Juveniles entering the ocean in years with strong spring upwelling returned as younger adults Juveniles entering the ocean in relatively warm years returned as younger adults These results are from a first-cut analysis which will be refined and updated Similar analysis will be done with hatchery fish
Thanks! Eric, Jennifer and Mark COE and BPA NOAA Lower Granite PIT-tag Team, especially Tiffani Marsh