Christopher Sullivan Chuck Warren

LSRCP Annual Meeting March 16, 2016

To assess the accuracy of using PIT tags to estimate adult returns for Steelhead and Chinook Salmon from hatcheries in Idaho

• PIT vs Parentage Based Tagging (PBT) estimates at LGR for

both Steelhead and Chinook Salmon • High level (entire run) • Stock/release site specific level

• Chinook case study for PIT expansion corrections at McCall • Corrected PIT expansions at adult trap on SFSR based on in-

ladder and hand scanned PITs

• Summary and Management Implications

Why compare PIT estimates to PBT? • Unbiased sampling design across the return

• High tagging rates that don’t change (>95% for most groups)

• High assignment rates for sampled adults

• Represents the entire return (i.e., USACE window count)

• Method for PIT tags • Expand PIT detections in the adult ladder at LGR by the juvenile

tag rate to estimate total number of stock/age specific returns

• Method for PBT • Tissue samples collected systematically across the returns

• The USACE window counts at LGR are parsed out using the

stock/age information obtained through PBT analysis

Age PIT Estimate PBT Estimate PIT Accountability

SY2013 1-Ocean 23,305 25,760 90%

2-Ocean 34,150 40,302 85%

Total 57,455 66,062 87%

SY2014 1-Ocean 36,820 35,754 103%

2-Ocean 15,281 26,970 57%

Total 52,101 62,724 83%

Age PIT Estimate PBT Estimate PIT Accountability

SY2013 1-Ocean 23,305 25,760 90%

2-Ocean 34,150 40,302 85%

Total 57,455 66,062 87%

SY2014 1-Ocean 36,820 35,754 103%

2-Ocean 15,281 26,970 57%

Total 52,101 62,724 83%

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Hatchery-Stock-BY Release Group

Spawn Year 2013 Adult Steelhead Escapement to LGD PBT Point Est. with 95% C.I. PIT Tag Est.

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Hatchery-Stock-BY Release Group

Spawn Year 2013 Adult Steelhead Escapement to LGD PBT Point Est. with 95% C.I. PIT Tag Est.

50% of PIT estimates below PBT by > 10% 35% of PIT estimates above PBT by > 10% 15% of PIT estimates within 10% of PBT

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Hatchery-Stock-BY Release Group

Spawn Year 2014 Adult Steelhead Escapement to LGD PBT Point Est. with 95% C.I. PIT Tag Est.

0

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4,000

6,000

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Hatchery-Stock-BY Release Group

Spawn Year 2014 Adult Steelhead Escapement to LGD PBT Point Est. with 95% C.I. PIT Tag Est.

57% of PIT estimates below PBT by > 10% 33% of PIT estimates above PBT by > 10% 10% of PIT estimates within 10% of PBT

Ad-Clipped Adults + Jacks

Return Year PIT Estimate PBT Estimate PIT Accountability

2012 34,882 46,316 75%

2013 26,882 40,099 67%

2014 47,146 63,875 74%

2015 63,072 91,678 69%

Average 71%

Adults

Return Year PIT Estimate PBT Estimate PIT Accountability 2012 32,958 43,269 76% 2013 15,312 26,061 59% 2014 35,525 52,734 67% 2015 54,533 81,418 67%

Average 67%

Jacks

Return Year PIT Estimate PBT Estimate PIT Accountability 2012 1,924 3,047 63% 2013 11,570 14,038 82% 2014 11,621 11,141 104% 2015 8,539 10,260 83%

Average 83%

ADULTS JACKS

Hatchery PIT

Estimate PBT

Estimate % PIT

Accountability PIT

Estimate PBT

Estimate % PIT

Accountability

Dworshak 6,114 12,617 48% 317 203 156%

Kooskia 3,294 8,289 40% 146 727 20%

Clearwater 9,780 12,633 77% 1,465 1,580 93%

TOTAL CLEARWATER R. 19,188 33,539 57% 1,928 2,510 77%

Rapid River 28,805 38,072 76% 1,607 2,806 57%

McCall 3,336 4,456 75% 1,252 1,283 98% Pahsimeroi 1,107 1,996 55% 0 143 0%

Sawtooth 2,097 3,355 63% 3,752 3,518 107%

TOTAL SALMON R. 35,345 47,879 74% 6,611 7,750 85%

GRAND TOTAL 54,533 81,418 67% 8,539 10,260 83%

PITs underrepresented PBT estimates at LGR in all years 13-17% for Steelhead 25-33% for Chinook Salmon

PITs underrepresented PBT estimates at LGR in all years 13-17% for Steelhead 25-33% for Chinook Salmon

Consistent underrepresentation for aggregate return, but

variability for individual cohorts and release sites

PITs underrepresented PBT estimates at LGR in all years 13-17% for Steelhead 25-33% for Chinook Salmon

Consistent underrepresentation for aggregate return, but

variability for individual cohorts and release sites

Accountability with PITs decreases with age for both species Tag loss more likely than differential mortality

Double-scanning for PIT tags at the adult trap allows us to correct for PIT detection efficiency of the array

•PIT array in adult ladder •Hand-scanning during trap work-up

Double-scanning for PIT tags at the adult trap allows us to correct for PIT detection efficiency of the array Total PITs detected for each age class are expanded by the detection efficiency

Double-scanning for PIT tags at the adult trap allows us to correct for PIT detection efficiency of the array Total PITs detected for each age class are expanded by the detection efficiency

Corrected Tag Rate =Total fish trapped by ageTotal RAL PIT tags at trap

PIT expansion rate for adults was higher than juvenile expansion rate for five consecutive brood years of South Fork Salmon River Chinook

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Tag Rate at ReleaseCorrected Tag Rates for JacksCorrected Tag Rates for 2-Ocean Adults

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There were too few PIT tags from these cohorts detected at the trap to make meaningful tag rate corrections

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Uncorrected PIT EstimateCorrected PIT EstimatePBT Estimate

PIT tags have their limitations…… • Appear to misrepresent the abundance of Steelhead and Chinook

• Underrepresentation of the aggregate return • Inconsistent across release sites and cohorts

• Tag loss may increase with age

PIT tags have their limitations…… • Appear to misrepresent the abundance of Steelhead and Chinook

• Underrepresentation of the aggregate return • Inconsistent across release sites and cohorts

• Tag loss may increase with age HOWEVER……

PIT tags are a very important management tool • Juvenile survival estimates • Adult run timing • In-season run strength for implementing/restricting fisheries • Broodstock planning • Conversion rates through the hydrosystem

• McCall Hatchery (South Fork Salmon River) • 52,000 PITs, split evenly between segregated/integrated smolts

• Sawtooth Hatchery (Upper Salmon River) • 18,900 PITs in segregated smolts, 1,000 in integrated smolts

• Clearwater Hatchery • Red River – 17,100 PITs • Selway – 17,100 PITs • Clear Creek – 9,500 PITs • Powell – 25,500 PITs

• Rapid River Hatchery • On-site release – 52,000 PITs

• Pahsimeroi Hatchery

• On-site release – 21,400 PITs

Tag Numbers by Hatchery for Steelhead Programs in BY2010 Clearwater 33,822 Hagerman 28,563 Magic Valley 32,752 Niagara Springs 27,966 Total 123,103

Hatchery Brood Year Stock Total Release PIT Tags Released

Clearwater

2009 DWOR 854,960 23,654

2010 DWOR 665,214 18,558 SFCR 213,173 15,264

2011 DWOR 546,420 4,868 SFCR 177,616 4,630

Hagerman

2009 EFNAT 120,918 6,804 SAW 1,290,915 21,128

2010 EFNAT 158,577 6,981 SAW 1,162,970 21,621

2011 EFNAT 196,144 7,052 SAW 1,205,719 21,511

Magic Valley

2009

DWOR 864,239 14,424 PAH 522,630 9,046 SAW 117,883 2,097 USAL 95,023 7,172

2010

DWOR 811,341 15,835 PAH 531,801 9,453 SAW 124,942 2,093 USAL 91,525 5,371

2011

DWOR 869,566 14,061 PAH 469,337 9,479 SAW 124,047 2,197 USAL 98,655 7,174

Niagara Springs

2009 OX 811,266 12,543 PAH 978,529 15,584

2010 OX 630,897 8,234 PAH 1,150,753 19,762

2011 OX 827,631 12,485 PAH 1,011,064 15,438

Steelhead