Movements and Survival of Juvenile and Adult Bull Trout

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Movements and Survival of Juvenile and Adult Bull
Trout

• Joseph Zydlewski
• U.S. Fish and Wildlife Service
• Columbia River Fisheries Program Office
• Vancouver, WA

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Collaborators and Cooperators

• Jim Byrne
• Washington Department of Fish and Wildlife
• Gayle Zydlewski
• Abernathy Fish Technology Center, USFWS

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Justification of study

• Bull trout are listed and have been heavily
  impacted by anthropogenic effects, including
  hydropower and habitat loss
• There is poor recruitment information for both
  juveniles and adults
• Monitoring juveniles augments adult spawning
  estimates by generating predictive data

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Bull trout life-history
High Gradient Stream
Juvenile 1-4yrs
Main-stem
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Ongoing Monitoring by WDFW

• Long term population estimates using visual
  mark-recapture
• Juvenile emigration indices using screw trap data

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Goals

• Quantify survival and year class of juveniles
• In-stream PIT tag interrogation
• Back pack PIT tag interrogation
• Screw trapping
• Quantify adult recruitment and juvenile to adult
  survival
• PIT tag juvenile migrants
• Re-capture adults in staging area

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Lewis River
Swift Reservoir
Rush Creek
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Monitoring movements into the main stem

• Tag juvenile bull trout with 23 mm PIT tags

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Use of 23 mm tags in salmonids

• Atlantic salmon
• (G. Zydlewski et al. 2001)
• Coho salmon and Steelhead trout
• (G. Zydlewski, unpublished data)
• Cutthroat Trout
• (J. Zydlewski, unpublished data)

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Use of 23mm Tags in Cutthroat Trout

• After 3 weeks, tagged fish (n102)
• 100 survival
• 100 tag retention
• positive growth

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Jim Byrne, WDFW, unpublished data
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Interrogation arrays

• Continuously monitor for emigrating juveniles and
  returning adults

Reader
Data Logging PC
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PIT tag array at Abernathy Creek
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Conduct in-stream surveys using a backpack
interrogator

• Enumerate non-migrants and estimate over-winter
  survival

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Adult recruitment

• Tagging of juveniles
• Rush Creek
• Screw trap

• Gill netting of adults
• Recapture of tagged fish
• Tag new captures

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Products

• Timing of emigration, prevalence of juvenile
  excursions into main stem areas
• Adult return timing, recruitment
• Estimates of year class survival
• Adult recruitment and repeat spawning

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