analysis of lfh pit tag sar s
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Analysis of LFH PIT tag SAR’s

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Analysis of LFH PIT tag SAR’s. 1995-2000 Releases. Design of Study. This study was designed to evaluate relationships among smolt travel time, survival, and environmental variables- NOT ADULT RETURN RATES. Design of Study.

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design of study
Design of Study
  • This study was designed to evaluate relationships among smolt travel time, survival, and environmental variables- NOT ADULT RETURN RATES
design of study1
Design of Study
  • This study was designed to evaluate relationships among smolt travel time, survival, and environmental variables- NOT ADULT RETURNS
  • Most non tagged juvenile fall chinook salmon (75-80%) are transported, therefore, SAR’s from fish slide-gated back to the river are not representative of the general population
study design
Study Design
  • In most years, releases (equal in size) were made upstream and downstream of the Salmon River and in some years the Clearwater River, from the end of May through early July at weekly intervals to provide estimates of survival and travel time over the entire fall chinook migration
study design1
Study Design
  • Smolt size and timing of releases were based on natural migrants from USFWS
study design2
Study Design
  • Smolt size and timing of releases were based on natural migrants from USFWS
  • Travel times, arrival dates at LGR, and survival to LGR were nearly the same for wild and hatchery fish in 1995-1998, and 2001, but survival was much lower for hatchery fish in 1999, 2000, and 2002.
preliminary results
Preliminary Results
  • From releases of 209,388 PIT tagged smolts, 615 adults have returned so far
preliminary results1
Preliminary Results
  • 7,234 smolts were transported
  • 58,047 smolts were bypassed
  • 21,603 smolts estimated never detected
  • 3,386* smolts migrated the following year
  • The rest died above Lower Granite Dam

*Unable to quantify for 1999 releases because of detection system changes

preliminary results2
Preliminary Results

Disposition# adults SAR*

Transported 100 1.38%

Bypassed 245 0.42%

Never detected 223 1.06%

Holdovers 42 1.24%

* LGR to LGR, estimated

preliminary results3
Preliminary Results
  • SAR from release to return to LGR was similar among release groups from early (late May/early June) to late (late June/early July) releases
preliminary results4
PreliminaryResults
  • SAR from release to return to LGR was similar among release groups from early (late May/early June) to late (late June/early July) releases
  • Estimated SAR from LGR to LGR (i.e., accounting for differences in estimated survival release-to-LGR) was substantially higher for the later release groups
preliminary results5
PreliminaryResults

SARSAR

Adultsrel-LGRSLGR-LGR

Early June 87 0.77% 41.7 2.10%

Mid June 103 0.91% 25.5 3.84%

Early July 73 0.64% 9.0 12.08%

1999 releases (incomplete returns)

conclusions
Conclusions
  • Hatchery fish were reasonable surrogates for wild fish in most years
conclusions1
Conclusions
  • Hatchery fish were reasonable surrogates for wild fish in most years
  • Since most fish are transported, their performance is the real issue, however we have little data for them
conclusions2
Conclusions
  • Hatchery fish were reasonable surrogates for wild fish in most years
  • Since most fish are transported, their performance is the real issue, however we have little data for them
  • For fish that remain inriver, SAR’s are higher for later migrants and fish that holdover, perhaps due to culling effects
conclusions3
Conclusions
  • We currently have insufficient data for transported fish to determine whether there are temporal trends in SAR
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