Adult Steelhead Monitoring Challenges
in Cedar Creek, WA
Josua Holowatz
&
Dan Rawding
Species of Concern:
Hatchery Strays and Natural Production
Coastal Cutthroat
Tule Fall Chinook
Winter Steelhead
Coho Salmon
Grist Mill Site
River Mile 2.5
Fishway constructed in 1958
Adult trap operated since 1999
Smolt Trap
operated since
1998
Smolt Monitoring Goals
•Unbiased estimates of coho, steelhead, & cutthroat smolt yield
(CV < 10%). Estimates of juvenile Chinook outmigrants if funding
is available
•Contribution of coho from a remote site incubator program is
based on otolith marks.
•CWT natural origin coho to estimate marine survival and fishery
contributions
Cedar Creek Coho and Steelhead Smolt Estimates
60,000
Coho Smolts
50,000
STD Smolts
40,000
30,000
20,000
10,000
Year
20
09
20
07
20
06
20
05
20
04
20
03
20
02
20
01
20
00
19
99
0
19
98
Estimate
70,000
Cedar Creek Adult Monitoring
Goals & Methods
• Estimate the abundance, age, & origin for
Tule Fall Chinook, coho, and winter steelhead
populations
• BioSample all adult salmonids trapped at the
fishway (River Mile 2.5)
• Tag all fish captured in the fishway for markrecapture abundance estimates
• Monitor Petersen assumptions needed for an
unbiased estimate
• Recover adult salmonids through a variety of
methods
Recapture Events
• Recapture event is a combination of carcass
recoveries (salmon), along with hoop trap &
resistance board weir recoveries (4 miles
upstream of the fishway)
• Recover steelhead kelts in the screw trap &
through seining above the resistance board
weir
• Estimate trap efficiency for steelhead
– Trapped fish are tagged and released below the
fishway
– Enumerate number of steelhead that successfully
re-ascend the fishway
– Estimate the proportion fish using the ladder
2001-03 Hoop Trap
• limited success at recapturing coho and steelhead due
to trap avoidance and large debris loads
Pre High Water Event
Post High Water Event
2006:Installed Resistance Board Weir at RM 6.1
Weir fishes efficiently until flows reach 850 CFS
Fully submerged panels
Leaf debris high water mark
Weir is not 100% efficient due to high
flows and debris
Fishway is operational until flows exceed 1250 CFS
Steelhead catch and flows 2007-2009
Average Steelhead
Catch at Fishway and Weir
10.00
9.00
8.00
Catch/CFS
7.00
6.00
5.00
Fishway Catch
4.00
3.00
Weir Catch
2.00
1.00
0.00
CFS x 100
Cedar Creek Flows
2007-08 water year
Thresholds
Coho
Steelhead
Fishway
Weir
Sampling kelts
Mark-recapture statistics & summary for
unmarked adult coho salmon and winter
steelhead
2009
Steelhead
26
3
24
1840
80
200
>100%
2009 Cedar Creek Adult
Estimates
3500
3000
Abundance
Category
Marks
Recaptures
Captures
U95%CI
L95%CI
N
CV
2009
Coho
1244
321
508
2973
1463
2218
17%
2500
2000
1500
1000
500
0
Coho
Steelhead
Species
Cedar Cr. Adult Steelhead Trap Effeciencies
Likelihood
0.25
2002
2003
0.2
2004
0.15
2005
2006
2007
2008
0.1
Maximum Likelihood Estimates
• trap efficiency
• % fish using ladder
•binomial distribution
•skewed or long tailed
•imprecise estimates
2009
0.05
0
0%
20%
40%
60%
80%
Trap Efficiency
Cedar Cr. Adult Steelhead Population Estimates
0.25
2002
2003
2004
2005
2006
2007
2008
2009
0.2
Likelihood
Maximum Likelihood Estimates
• Abundance
•binomial approximation to
hypergeometric distribution
•skewed or long tailed
•very imprecise estimates
0.15
0.1
0.05
0
0
200
400
Abundance
600
800
Rivot, E., and E. Prevost. 2002.
Hierarchical Bayesian analysis of capturemark-recapture data. Can. J. Fish. Aquat.
Sci. 53:2157-2165.
• Application of Rivot et al. 2002 to Cedar
Creek adult steelhead estimate
• Posterior probability = prior X likelihood
• Non-informative priors & hyperpriors
(hierarchical models) – priors have little
influence on posterior probabilities
• Common distributions for trap efficiency &
population estimate are the beta and normal
probability distributions, respectively
• Other distributions could be used
Hierarchical Modeling
• all annual trap efficiencies
Cedar Cr. Adult Steelhead Trap Effeciencies
0.25
2002
2003
2004
Likelihood
0.2
2005
2006
2007
0.15
2008
2009
Hierarchical
0.1
0.05
0
0%
20%
40%
60%
80%
Trap Efficiency
Hierarchical Modeling
• shrink estimates toward the
Cedar Cr. Adult Steelhead Population Estimates
0.25
2002
2003
2004
2005
2006
2007
2008
2009
Hierarchical
0.2
Likelihood
mean, which yields improved
precision
• can be used for both trap
efficiency & population
abundance
• compromise between
individual and fully pooled
estimates
come from a common
distribution of trap efficiencies
and their ordering does not
affect the model
(exchangeable)
• borrow strength from other
trap efficiencies because they
are similar
0.15
0.1
0.05
0
0
200
400
Abundance
600
800
I
T r T r nd_
ap ap 1
&N_1 99
_199 9
9
In 999
T r T r d_
ap ap 2
&N_2 00
_200 0
000
I
n
T r T r d_ 0
ap ap 2
&N_2 00
_200 1
001
I
n
T r T r d_ 1
ap ap 2
&N_2 00
_200 2
002
I
n
T r T r d_ 2
ap ap 2
&N_2 00
_200 3
3
In 003
T
T r r d_
ap ap 2
&N_2 00
_200 4
4
In 004
T
T r r d_
ap ap 2
&N_2 00
_200 5
005
I
n
T r T r d_ 5
ap ap 2
&N_2 00
_200 6
006
I
n
T r T r d_ 6
ap ap 2
&N_2 00
_200 7
007
I
n
T r T r d_ 7
ap ap 2
&N_2 00
_20088
I 0
Tr Tr nd_ 08
ap ap 2
&N_2 00
_200 9
009
9
Population Estimate
Cedar Creek Adult Steelhead Estimates (median) with 95%CI by
Year and Method
2000
1500
1000
500
0
Method_Year
I
T r T r nd_
ap ap 19
&N_1 99
_1999
9
I
T r T r nd_ 99
ap ap 2
&N_2 00
_20000
00
I
T r T r nd_ 0
ap ap 20
&N_2 01
_2001
In 001
T
T r r d_
ap ap 2
&N_2 00
_20022
00
I
T r T r nd_ 2
ap ap 20
&N_2 03
_2003
0
I
T r T r nd_ 03
ap ap 2
&N_2 00
_20044
In 004
T
T r r d_
ap ap 20
&N_2 05
_2005
0
I
T r T r nd_ 05
ap ap 2
&N_2 00
_20066
In 006
T
T r r d_
ap ap 20
&N_2 07
_2007
0
I
T r T r nd_ 07
ap ap 2
&N_2 00
_20088
00
I
T r T r nd_ 8
ap ap 20
&N_2 09
_2009
00
9
Coefficient of Variation
CV for Adult Steelhead Estimates by Year and Method
100%
75%
50%
25%
0%
Year_Method
Summary
• Annual steelhead smolt estimates are an
order of magnitude lower than coho. Mean
steelhead smolts are 2,900 compared to
38,000 for coho salmon.
• Our adult steelhead estimates are also an
order of magnitude lower than coho. For
example, in 2009 the steelhead abundance
was 200 fish compared to 2,200 for coho.
• Cedar Cr. Steelhead program should be
designed to provide more precise abundance
estimates.
• Hierarchical approach is a good approach
when dealing with sparse data and common
distributions.
Cedar Creek Adult Steelhead
Recommendations
• Mark all wild steelhead captured at the
fishway trap.
• Release all marked steelhead below the
fishway trap to estimate ladder use.
• The recapture events should be designed to
obtain at least 10 recaptures through the
resistance board weir, seining and the screw
trap catch of kelts.
• If recaptures are sparse, recaptures can be
supplemented through snorkeling.