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 SiteRiver Mile 2.5

Fishway constructed in 1958Adult 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

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

19981999

20002001

20022003

20042005

20062007

2009

Year

Esti

mat

e

Coho Smolts

STD Smolts

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 mark-recapture 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

Pre High Water Event Post High Water Event

• limited success at recapturing coho and steelhead due to trap avoidance and large debris loads

2006:Installed Resistance Board Weir at RM 6.1

Weir fishes efficiently until flows reach 850 CFS

Leaf debris high water mark

Fully submerged panels

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

Cedar Creek Flows 2007-08 water year

Coho Steelhead

Thresholds

FishwayWeir

Sampling kelts

2009 Cedar Creek Adult Estimates

0

500

1000

1500

2000

2500

3000

3500

Coho Steelhead

Species

Ab

un

da

nc

e

Mark-recapture statistics & summary for unmarked adult coho salmon and winter

steelhead2009 2009

Category Coho SteelheadMarks 1244 26

Recaptures 321 3Captures 508 24U95%CI 2973 1840L95%CI 1463 80

N 2218 200CV 17% >100%

Maximum Likelihood Estimates• trap efficiency

• % fish using ladder•binomial distribution•skewed or long tailed•imprecise estimates

Maximum Likelihood Estimates• Abundance

•binomial approximation tohypergeometric distribution•skewed or long tailed•very imprecise estimates

Cedar Cr. Adult Steelhead Trap Effeciencies

0

0.05

0.1

0.15

0.2

0.25

0% 20% 40% 60% 80%

Trap Efficiency

Lik

elih

oo

d

2002

2003

2004

2005

2006

2007

2008

2009

Cedar Cr. Adult Steelhead Population Estimates

0

0.05

0.1

0.15

0.2

0.25

0 200 400 600 800

Abundance

Lik

elih

oo

d2002

2003

2004

2005

2006

2007

2008

2009

Rivot, E., and E. Prevost. 2002. Hierarchical Bayesian analysis of capture-mark-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 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

Hierarchical Modeling• shrink estimates toward the mean, which yields improved precision• can be used for both trap efficiency & population abundance• compromise between individual and fully pooled estimates

Cedar Cr. Adult Steelhead Trap Effeciencies

0

0.05

0.1

0.15

0.2

0.25

0% 20% 40% 60% 80%

Trap Efficiency

Lik

elih

oo

d

2002

2003

2004

2005

2006

2007

2008

2009

Hierarchical

Cedar Cr. Adult Steelhead Population Estimates

0

0.05

0.1

0.15

0.2

0.25

0 200 400 600 800

Abundance

Lik

elih

oo

d2002

2003

2004

2005

2006

2007

2008

2009

Hierarchical

Cedar Creek Adult Steelhead Estimates (median) with 95%CI by Year and Method

0

500

1000

1500

2000

Method_Year

Po

pu

lati

on

Es

tim

ate

CV for Adult Steelhead Estimates by Year and Method

0%

25%

50%

75%

100%

Year_Method

Co

effic

ien

t of V

aria

tion

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.