Bull Trout Life History:

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Bull Trout Life History
Dworshak Reservoir, North Fork Clearwater River
Drainage, ID. Idaho Department of Fish and
Game Clearwater Region Lewiston, ID
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ISSUES

• North Fork Clearwater River bull trout population
  is isolated due to Dworshak Dam.
• Loss of anadromous fish in prey base of bull
  trout.
• Unknown if entrainment is occurring and
  significance to population.
• Unknown the relationship Dworshak Reservoir plays
  in bull trout life history in North Fork
  Clearwater River drainage.

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OBJECTIVES

• Characterize basic biology of bull trout in North
  Fork Clearwater River drainage.
• Determine bull trout temporal and spatial
  distribution within Dworshak Project Area.
• Determine timing and extent of migration into the
  North Fork Clearwater and Little North Fork
  Clearwater Rivers.
• Assess potential entrainment associated with the
  operations of Dworshak Dam.
• Describe relative abundance of kokanee fry to
  bull trout distribution and season utilization in
  bull trout diets.

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APPROACH

• Radio Telemetry
• Dietary Analysis
• Entrainment Research

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WHAT WE KNOW TO DATE

• Bull trout utilize the reservoir year around.
• Bull trout are located below Dworshak Reservoir.
• 105 bull trout have been radio tagged over the
  past two years in the reservoir the majority of
  these fish moved into tributaries during late
  spring 12 remained in the reservoir all summer.

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PRODUCT

• Operating recommendations for Dworshak Dam that
  will benefit bull trout.
• Develop land management guidelines.

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