The relationship of Snake River stream-type Chinook survival rates to in-river, ocean and climate conditions Howard Schaller, USFWS * Charlie Petrosky, IDFG NPCC Science/Policy Workshop - September 12, 2007

Snake River Salmon and steelhead declined since completion of hydrosystem Survival declines for stream-type Chinook were in the Smolt-to- adult life stage

mean bad future climate/ ocean good future climate/ ocean hydro delayed mort ocean regime delayed mort hydro delayed mort ocean regime delayed mort Stock viability delayed mort Stock viability delayed mort median Is there evidence linking estuary and early-ocean mortality to the migration experience through the hydrosystem? THE Critical Uncertainty that differentiated risk levels amongst options in the 2000 Biological Opinion (Peters and Marmorek 2001; Karieva et al. 2000; Wilson 2003)

Different passage routes over, through, or around dams Transport via barge and truck: Bypass facility stress Can not separate species Disease exposure Change estuary arrival timing Inriver migrants also face challenges from the altered migration route

Hydrosystem effects on Smolt to Adult Survival Rates (SARs) Mortality within the hydrosystem (measurable) Mortality in Estuary/Early Ocean life stages Transported Measurable (relative) – survive ~½ as well as in-river migrants in ocean (D ~ 0.5) In-river migrants: Fish condition – injury, stress, bioenergetics Delayed migration – bioenergetic costs – physiological state vs. arrival timing – miss optimal environmental conditions Mostly indirect inferences Berggren et al. (2006); Budy et al. (2002)

Multiple Analytical Methods for mortality inferences 1.Compare Spawner-Recruit residuals  upriver vs. downriver populations 2.Multi-stock S-R models  differential and common mortality estimates between upriver & downriver populations 3.Compare SARs  PIT tags, upriver vs. downriver populations 4.Multiple regression  upriver populations only vs. migration & ocean conditions

Snake River ESU Downriver populations Spatial/temporal comparisons Spawner-Recruit models using downriver populations

Downriver populations Schaller et al. (1999); Deriso et al. (2001);Schaller and Petrosky (2007)  Snake R. survive ¼ to 1/3 as well as downriver since dams  Common annual mortality patterns between upriver & downriver populations  Common year effects correlate with good and poor ocean conditions Spawner-recruit analyses Snake River populations

Snake River ESU Downriver populations PIT tag SAR comparisons wild Snake and John Day stream-type Chinook, Comparative Survival Study: CSS 10-year Report (2007)

PIT tag studies:  Downriver SARs are 3-4X Snake SARs  Snake River SARs generally < 2 to 6% SAR CSS 10-year Report (2007)

 Snake River survival 1/3 to ¼ survival of John Day populations CSS 10-year Report (2007) ; Schaller and Petrosky (2007) Spawner-Recruit analysis vs SAR comparisons: estimated difference in mortality Snake vs. downriver

Multiple Regression for Snake River alone 1 st year ocean survival (s3 in Zabel et al. 2006) Environmental variables: migration corridor & ocean Model selection criteria: AIC and BIC

Water Travel Time: Lewiston to Bonneville Dam pre-dam ~2 days; current ~ 19 days (10-40 days) 1938 (BON), 1953 (MCN), 1957 (TDD), 1961 (IHR), 1968 (JDA), 1969 (LMN), 1970 (LGS), 1975 (LGR)

Coastal Upwelling Process Pacific Decadal Oscillation Interdecadal climate variability in the North Pacific – (Sea Surface Temperature) Coastal Upwelling Index based upon Ekman's theory of mass transport due to wind stress - 45 o N – (productivity) “Good Ocean” Cool phase PDO April Upwelling Oct Downwelling

Expected change in 1 st year ocean survival vs. WTT, Sept. PDO & Apr. Upwelling Response to WTT - similar to results using upriver/downriver populations Current WTT Pre-dam. WTT Best fit (adj. R 2 =0.71), simplest model ( best BIC )

Survival Patterns for Snake Populations Multiple Regression Analysis: WTT was a variable that consistently explained patterns in various survival metrics These measures of survival were best described by WTT during smolt migration and ocean/climatic variables –Stream-type Chinook S3 –Stream-type Chinook SARs –Stream-type Chinook R/S –Steelhead S3 –Steelhead SARs

Summary Upriver/downriver population performance indicates the hydrosystem is a key factor influencing early ocean mortality Analyses of only Snake River populations - a significant component of early ocean survival is related to impacts of the dams –Magnitude of hydrosystem related early ocean mortality ~ similar to other methods

Conclusions Multiple lines of evidence indicate mortality in the early ocean life stage is related to cumulative impacts of the hydropower system Recovery efforts need to address these cumulative impacts