lake roosevelt burbot population assessment project no. 2008-115-00 jason mclellan confederated...
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Lake Roosevelt Burbot Population Assessment
Project No. 2008-115-00
Jason McLellanConfederated Tribes of the Colville Reservation
Janu
ary
18, 2
012
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Background
• Status reviews (1997, 2001)• “Healthy”• Abundance increasing• Poor growth/condition• Based on by-catch
• Lack standardized monitoring
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Background
• Fall Walleye Index Netting (FWIN)• BPA Project No. 1994-043-00• Gill nets
• Data – burbot by-catch• No analysis
• Burbot monitoring?
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Goal and Objective
• Goal - Healthy & harvestable population
• Objective - Monitor population status and trend
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Management Questions
1. Is FWIN by-catch adequate for monitoring?
2. Differences between gear types?
3. Most efficient gear for non-lethal capture?
4. Relationship - catch rate and abundance?
5. Status of the population? 5
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Project Design
• Evaluate FWIN (2013-2017)• analyze existing data
• Gear Comparisons (2013-2015)• FWIN gill nets, cod traps, trammel nets
• Stock Assessment (2013-2017)• Adapt – gear comparison
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Study Design
• Gear Comparison FWIN• FWIN gill nets, cod traps, trammel nets• GRTS strategy• 50 sets/gear• November (1 wk)
• Gear Comparison/Stock Assessment• cod traps, trammel nets• GRTS strategy• 240 sets/gear• late Fall - early Spring 7
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Analysis
• FWIN• Analyze existing data – year effect, power analysis• Gear comparison – gear type and year effects
• Gear Comparison/Stock Assessment• Analyze indices – gear and year effects, power• Capture-recapture – abundance & survival• Use most efficient after 3 years
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Analysis
Abundance
Catch rate (C/f) ANOVA
Proportion positive catch
(Ep)
Binomial Logistic Regression
Capture-recapture Robust Design
Survival Capture-recapture Robust Design
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Analysis
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Size Structure
Length-Frequency
Cumulative Frequency
Distribution
Mean Length ANOVA
Proportional Size Distribution
Ordinal Logistic Regression
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Analysis
Condition
Mean Relative Weight (Wr)
ANOVA
Length-Weight Relationship ANCOVA
Growth Capture-recapture
Absolute Growth Rate
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Analysis
• Catch rate – abundance relationship
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Management Implications
• Current status and trends
• Standardized stock assessment protocol
• Standardized data for management
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Questions?
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