Adult Steelhead Abundance
Estimates Based on PIT Tag
Arrays in Idaho
Rick Orme,
Nez Perce Tribe
Department of Fisheries Resources Management
and
Chris Beasley and Jody White
Quantitative Consultants
Background
The Integrated Status and Effectiveness
Monitoring Project (ISEMP)
• Design, implement, test, and evaluate Status and
Trends and Effectiveness Monitoring programs for
salmon and steelhead populations and habitat.
• Determine whether innovative methods can be employed
to increase the accuracy and precision of juvenile and
adult abundance estimates at the subpopulation,
population, and major population group (MPG) scales.
• Anadromous Monitoring Strategy: high precision
abundance data for at least one population per MPG.
PIT Tag Array
• In-stream antennas
Existing ISEMP
arrays
Methods
LGD sampling
Number / Estimate
Population
Estimated #
Sampled &
Tagged
Date
- Systematic sample
- Consistent sample rate
PIT tags
Ratio
(Expansion
Factor)
Methods
Population estimate using arrays
Array 1
M = Marks
= MC/R
Array 2
C = Captures
R = Recaptures
ESCAPEMENT
Precision
Starting Population Estimate, (complex)
Sample rate and adjustment, SbyC fish, August & December passages,
fall back, --- adapt fall Chinook run reconstruction methodology
Estimated Number of PIT Tags
Variables
Model
Response Variable
Escapement
4 levels
CV
Percent Tagged
4 levels
Efficiency
5 – 99%
Conversion
5 – 99%
= SE / Mean
Precision
Conversion Rate (Array A to Array B)
CV of Escapement
0.05
0.9
0.8
0.7
0.10
0.05
0.15
0.20
0.25
0.30
Stream Escapement
= 250
0.6
Tag Ratio
= 15:1 (6.7%)
0.5
0.10
0.4
0.3
0.2
0.35
0.40
0.45
0.50
0.55
0.60
0.15
0.20
0.25
0.30
0.1
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
Efficiency of Array A
0.05
Precision
35
Escapement = 250
Escapement = 2,000
0.04
30
25
0.03
20
15
0.02
10
0.01
5
0.00
0
0
2
4
6
8
10
12
14
Percent of Population PIT Tagged
Efficiency = 90%
Conversion = 90%
16
Number of Recaptures
CV of Escapement Estimate
0.05
Assumptions
• PIT Tags Representative of Population
– Sub-sample (LGD)
• Systematic with a consistent sample rate
• Pre-array
– Tag loss, tag induced mortality
• Mark-recapture
– Mark loss, missed marks, equally capture prob., equal mortality,
random mixing, no additions, # recaptures
Project Status
• Installed arrays in 2009
• Initiated adult tagging fall 2009
• Patiently waiting for adults
Acknowledgments
BPA provided
funding
Chris Beasley, Jody White
Bill Young, Jason Vogel
3D9.1BF2328B20
3D9.QBF1641BB4
3D9.1UF1955DD2
3D9.1BE1970B60
3D9.1BFS971444
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3D9.1BF1AI1964
3D9.1BF232OD0D
3D9.1BF2330NF0
3D9.1BF236AFS8
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3D9.1BF23A0EB4