Estimates of Steelhead Harvest Rates Based on PIT Tag Sampling in Columbia River Fisheries

Estimates of Steelhead Harvest Rates Based on PIT Tag Sampling in

Columbia River Fisheries

Steve VanderPloeg & Dan Rawding

Outline

• Introduce fishery sampling for PIT tags• Summarize detection study• Report on basic sampling statistics• Example for harvest rate calculations

– Preliminary steelhead harvest rates based on Zone 6 sampling and BON (Bonneville Dam) detections for selected tag groups

– More work to be done

Fishery Sampling

• BPA funded WDFW to sample mainstem Columbia River fisheries to fill a gap in the PIT tag recovery program.

• Sampling program includes sport, commercial, and treaty fisheries in the Columbia River.

• Initiated in August 2010 with commercial and treaty fishery sampling.

• Sport sampling was added in Feb 2011.

Fishery Sampling Goals

• Report fishery recovery information to PTAGIS

• Expand PIT tag recoveries to estimate harvest of PIT tag groups

• Estimate harvest rates of PIT tag groups

Data for Harvest Estimates• Build on existing CWT

recovery program• # of harvested fish with

PIT tags• Detection rate for

presence of PIT tags• # of harvested fish

sampled for PIT tags• Total number of

harvested fish

2010 Hatchery Study for determining detection rates for presence of PIT tags.

Biomark Pocket Reader (1)

Psion Teklogix data logger with RFID – LF module (1)

All Flex RS601-3 (4)Destron Fearing FS2001F-ISO 'Cheese Block' w/ Racket with Racket antenna (4)

Models (#)

Models (#)

Destron Fearing FS2001F-ISO 'Cheese Block' w/ Biomark Flat Plate (1)

Destron Fearing FS2001F-ISO 'Cheese Block' w/ Biomark 24” square (1)

Study Design

• PIT tag 130 - 200 adult steelhead, coho, and Chinook salmon at Skamania and Kalama Hatcheries

• Hold salmon for 7 days and steelhead for 30 days, then sacrifice fish

• Follow PIT tag sampling protocols

Scanning a Fish for a PIT tagHand-held detectors PIT sampling protocol

• Sacrifice fish and lay groups of 50 fish out on a series of tables.

• Space between fish ~ 18 inches to avoid tag collision.

• At the end of samp-ling, the 50 fish were passed over the flat plate and through the 24 “ square in the same order (1,2,…,50)

• First sampler uses 'Cheese Block' w/ Racket (>99% detection rate) & recorder takes notes on presence / absence of PIT tag for each fish and records PIT tag #.

• Tag detection can now be referenced for other samplers with different models and serial #.

• Multiple passes ensures detection probability ~ 100% for each fish.

24 “ Square antenna• Variable detection rates; rates dependent on fish

orientation, distance from the edge of the antenna, and speed of fish passing through.

• When sampling protocols were standardized; a slide was used and fish were passed head first through the square, next to the antenna: PIT tag detection rates were 99.5% and 100% for coho and steelhead, respectively.

Flat Plate Detector• Detection rates were high

but sometimes variable.• Variability occurred when

samplers were in a hurry (coho) & did not pass the entire fish over the plate; detection rate: 93.3%.

• When fish were passed within range, detection rates were 99.4% and 100% for Chinook and steelhead respectively.

Single Model Results for Chinook

• Older/broken All Flex model had a detection rate of 63%.

• Older/broken model Pocket Reader had a detection rate of 6%.

• Psion Teklogix data logger with RFID had a detection rate of 98.9%

SalmonChinook PIT Tag Detection Rates

with 95%CI

95%

96%

97%

98%

99%

100%

AF#1AF#3

AF#4CB#1

CB#2CB#3

CB#4 FL

Unit

De

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tio

n P

rob

ab

ility

Coho PIT Tag Detection Rates with 95%CI

97%

98%

99%

100%

AF1AF3

AF4CB#1

CB#2CB#3

CB#4 SQ

Unit

De

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ility

Steelhead• Chinook and coho test ~ 100% of the fish

in the sample were tagged. For steelhead less than 50% of the sample was tagged which is more similar to field conditions.

• Found similar detection rates (> 99%) as observed for Chinook and coho salmon with All Flex, 'Cheese Block' w/ Racket, 24” square, and flat plate.

Detection Conclusions

• Standardization of sampling protocols allowed for repeatable results between samplers and units.

• Field Protocol = two pass method• Other results

– No difference in detection rates based on tag location– No difference in detection rates between species– No difference in detection rates between samplers

Fall Treaty Sampling• 2010 only includes fall

fishery, not C&S, sockeye, or spring, summer, and winter fisheries

• Fall harvest rates under- estimates harvest for steelhead because they are also caught in other fisheries

• Assumes commercial fish sales are representative (same as CWT assumption)

• Assumes PIT tag groups are representative of untagged fish

Fall Commercial and Treaty Sampling

• Fall Commercial and Treaty (Zone 6) sampling in 2010

• 296 tags reported to PTAGIS• Most with bio-data length, species, mark status

Species BON Count BON PIT Z6 Catch Z6 Sampled % SampledF Chinook 530971 5807 138836 19350 13.94%Coho 124484 660 9555 1318 13.79%Steelhead 410390 9973 21308 3663 17.19%

Zone 6 Summary

f o r ( i I N 1 : b i o s a mp l e s )

Ha r v Ra t e

Su m_ Gr o u p [ i ]

BON_ Gr o u p

No . Gr o u p [ i ]

p r o p _ ms mp l

Ad j _ GT a g s [ i ]

m_ s a mp l e s

PI T _ Gr o u p [ i ]

p _ d e t

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No . F i s h l b s

a v g _ wt

we i g h t s [ i ]

t a u _ wt

mu _ wt

Direct Acyclic Graph (DAG) for Estimation of Harvest Rates

#estimate number of fish based on tickets by period

#estimate detection rate Of PIT tag readers

#Estimate expanded PIT Tags by sampling periodEstimate Harvest

Rate by Group

Steelhead PIT tags at BON, 2010

• From Apr 1 to Oct 31 there were over 7000 individual adult steelhead detections at BON

• 141 tag sites contributed to these adults passing at BON

• Adult returns by release site ranged from a low of 1 to a high of 1,658 from LWG release

• For analysis, individual tag groups were grouped together and analyzed individually

Recommendations

• WDFW successfully built on CWT sampling infrastructure to add other sampling (genetic, PIT tags, etc.).

• Recommend ODFW get funded for similar effort, which should increase PIT tag fishery recoveries.

• Recommend Zone 6 catch to be sampled and reported by pool.

• Coordination with Accord treaty PIT tag sampling proposal because C&S and OTB sales are not currently sampled for PIT tags.

Summary• Individual tag groups are often small, which can lead to

imprecise & possible unrepresentative harvest rates• Framework to estimate harvest rates by group:

– Pooled Analysis DPS & run timing at BON– Alternate Approach – Hierarchical Model

• All data are preliminary & additional work is needed– Zone 6 over the bank sales variance was not available

(2010)– In 2011, sampling included Sport, commercial and

treaty

Acknowledgements• Various WDFW, ODFW, IDFG, and PSMFC biologists for sharing

experiences with portable PIT tag sampling equipment• Joe Hymer and Vancouver PSMFC & WDFW sampling staff for

the implementation of commercial and treaty sampling. WDFW, PSMFC, and NOAA staff that assisted in this PIT tag detection study

• Michelle Groesbeck (WDFW) and Bob Woodard (WDFW) for detection study and for recommendation on data collection and ultimately data logger programming and database design.

• Dave Marvin (PSMFC) and Rick Golden (BPA) for support of this project.

• US v. OR TAC (Robin, Stuart, & Rodger) for supplying preliminary Zone 6 Fall harvest data. Doug Case (ODFW) & Ron Roler (WDFW) for landings & biosample data. Alan Byrne & Jay Hesse for help with Salmon & Clearwater groups