Juvenile survival, travel time and the in-river environmentPresenter: Steve Haeseker

CSS Annual Meeting Apr 2nd 2010

Objectives:Develop models that explain variation in migration time and survival through the hydrosystem

Measure and monitor juvenile Chinook and steelhead migration time and survival through the hydrosystemExamine associations between environmental factors and migration time and survival

Monitoring methods:Two reaches: LGR-MCN (CHW, CHH, STH&W) MCN-BON (CHH&W, STH&W)Weekly release cohorts of PIT-tagged fishEstimated median fish travel time (FTT) and survival rate

Environmental and Management Factors: Seasonality (Julian Day) Temperature Turbidity Average percent spill Water travel time (WTT, days)

Water Transit Time (WTT)Estimate of the number of days required for average water particle to transit a reservoir3 days2.5 days2.5 days8 days

98020499 0705 06000103Yearling Chinook median travel times

98020499 0705 06000103Yearling Chinook median travel times

Yearling Chinook median travel timesEnvironmental and management factors: WTT, percent spill, Julian day98020499 0705 0600010394%88%

Steelhead median travel times98020499 070506000103

Steelhead median travel times98020499 070506000103

Steelhead median travel timesEnvironmental and management factors: WTT, percent spill, Julian day98020499 07050600010390%89%

Mid-late AprilEarly MayLate MayPercent SpillWater Transit Time (days)yearling Chinook travel time (days)

Early MayLate MayPercent SpillWater Transit Time (days)Mid-late Aprilyearling Chinook travel time (days)

Early MayMid-late MayPercent SpillWater Transit Time (days)Mid-late Aprilyearling Chinook travel time (days)

Early MayMid-late MayPercent SpillMid-late AprilWater Transit Time (days)steelhead travel time (days)

Early MayMid-late MayPercent SpillMid-late AprilWater Transit Time (days)steelhead travel time (days)

Early MayMid-late MayPercent SpillMid-late AprilWater Transit Time (days)steelhead travel time (days)

Early MayMid-late MayPercent SpillWater Transit Time (days)Mid-late AprilPercent SpillChinooksteelhead

Early MayMid-late MayPercent SpillUnimpounded travel time = 5 to 9 days (Raymond 1979)Mid-late AprilPercent SpillChinooksteelhead

Mortality approach to survivalMortality = 1 - SurvivalIf daily survival is 0.98, then daily mortality is 0.02 (2%)SurvivalMigration time (days)90%61%37%If we can predict migration time and daily mortality, then we can predict survival

yearling Chinook mortality rates98020499 070506000103LGR-MCNMCN-BON

yearling Chinook mortality rates98020499 070506000103LGR-MCNMCN-BON

yearling Chinook mortality ratesLGR-MCNMCN-BONFactors: WTT, Julian dayFactors: Julian day98020499 07050600010325%45%

LGR-MCNMCN-BONsteelhead mortality rates 98020499 070506000103

LGR-MCNMCN-BONsteelhead mortality rates 98020499 070506000103

LGR-MCNMCN-BONFactors: WTT, Julian day, spillFactors: temperaturesteelhead mortality rates 98020499 07050600010354%51%

Mid-late AprilMid-late MayEarly Mayyearling Chinook daily mortalityWater Transit Time (days)

Early MayMid-late MayPercent SpillWater Transit Time (days)Mid-late Aprilsteelhead daily mortality

Early MayMid-late MayPercent SpillWater Transit Time (days)Mid-late Aprilsteelhead daily mortality

Early MayMid-late MayPercent SpillWater Transit Time (days)Mid-late Aprilsteelhead daily mortality

Yearling Chinook survivalLGR-MCNMCN-BON98990402030001060705990402030001060705Outmigration year

Yearling Chinook survivalLGR-MCNMCN-BON98990402030001060705990402030001060705Outmigration year

Yearling Chinook survivalLGR-MCNMCN-BON9899040203000106070599040203000106070563%38%Outmigration year

LGR-MCNMCN-BONsteelhead survival98990402030001060705990402030001060705Outmigration year

LGR-MCNMCN-BONsteelhead survival98990402030001060705990402030001060705Outmigration year

LGR-MCNMCN-BONsteelhead survival9899040203000106070599040203000106070576%70%Outmigration year

Early MayMid-late MayPercent SpillWater Transit Time (days)Mid-late AprilYearling Chinook survival

Early MayMid-late MayPercent SpillWater Transit Time (days)Mid-late AprilSteelhead survival

Percent SpillWater Transit Time (days)

Percent SpillUnimpounded Chinook survival = ~ 0.89 (Raymond 1979)

Travel time is related to river velocity: the higher the water velocity, the higher the rate of fish migration.

Impounding the river reduced the river velocity and migration rate of both juvenile Chinook salmon and steelheads to one-third that through free-flowing stretches of river.

Prior to construction of new dams (1966 to 1968), survival of wild Chinook salmon from the Salmon River to Ice Harbor Dam averaged 89% (range 85 to 95%). Following completion of Lower Monumental and Little Goose Dams (1970), average survival to Ice Harbor Dam sharply declined to 33% (range 12 to 50%).31 years ago-Raymond (1979)

ConclusionsJuvenile travel times, mortality rates and survival rates through the hydrosystem are strongly influenced by managed river conditions (water transit time and spill levels).

Statistical relationships accurately predict the effects of environmental factors and management strategies on migration and survival rates of juvenile yearling Chinook and steelhead.

Improvements in in-river survival and travel times can be achieved through reductions in water transit time or increased spill.