Steelhead Trout Production Studies at Sitkoh Creek, Southeast Alaska, 2003 – 2007

PIT-tagging, digital scale imaging/ageing & brood-tables

March 2008 Pacific Coast Steelhead Management Meeting, Boise Idaho

Alaska Department of Fish and Game

Division of Sport FishResearch funded by Federal Aid in Sport Fish Restoration Act (16 U.S.C. 777-777K ) under Projects F-10-18 and 20, Job R-1-9.

Dave Love

ObjectivesObjectives Adult steelhead & steelhead smolts: counts, PIT Adult steelhead & steelhead smolts: counts, PIT

tagging, ASLtagging, ASL Steelhead parr: minnow trapping for age and Steelhead parr: minnow trapping for age and

length datalength data Cutthroat, rainbow trout and Dolly Varden char: Cutthroat, rainbow trout and Dolly Varden char:

counts, length frequenciescounts, length frequencies

Sitkoh Ck Project-Sitkoh Ck Project- objectives and goals objectives and goals

GoalGoal: Define minimum # to fully seed habitat: Define minimum # to fully seed habitat Smolt per spawner index, brood-table reconstructionSmolt per spawner index, brood-table reconstruction

Smolt per useable habitat estimate – habitat projectSmolt per useable habitat estimate – habitat project

Expansion factor estimates - snorkel surveysExpansion factor estimates - snorkel surveys

Sitkoh Ck - Sitkoh Ck - upstream and downstream trapsupstream and downstream traps

Sitkoh Ck Project - PIT taggingSitkoh Ck Project - PIT tagging

Sitkoh Ck Project - PIT taggingSitkoh Ck Project - PIT tagging

Sitkoh Creek Weir Sitkoh Creek Weir – counts, sex ratios, lengths– counts, sex ratios, lengths

1,691 2)3,5612,2303,7423,166# downstreamSMOLT EMIGRATION

249556Number untagged82%76%67%73%68%% survival to kelt345292363555460# downstream

ADULT EMIGRATION66%65%67%61%62%% Female34%35%33%39%38%% Male

465-915548-923550 - 935576 - 930555 - 910Length range (mm FL)742749753740751Mean length (mm FL)

422 1)395538758672# upstreamADULT IMMIGRATION

20072006200520042003Sample year

1) Peterson estimate & Chapman’s modification, range 408-437, SE(N)=7.3

2) maybe an incomplete count, due to cold spring water temps, early weir removal

Sitkoh Ck Project Sitkoh Ck Project – digital scale imaging– digital scale imaging

Screen Scan Microfiche & ScanPro software

Leica DMD108 electronic microscope

Sitkoh Ck Project- freshwater scale ageingSitkoh Ck Project- freshwater scale ageing Develop method based on common scale characteristicsDevelop method based on common scale characteristics

Sitkoh Ck = spring spawning life-historySitkoh Ck = spring spawning life-history Freshwater and marine components to scaleFreshwater and marine components to scale

Known ocean ages from PIT taggingKnown ocean ages from PIT tagging Electronic images made & archivedElectronic images made & archived Freshwater ages –triplicate reads, multiple readers, read repeatability, Freshwater ages –triplicate reads, multiple readers, read repeatability,

paired scale & otolith comparisonspaired scale & otolith comparisons

Sitkoh Project- freshwater scale ageingSitkoh Project- freshwater scale ageing

91.398.391.391.9 % repeatability8.71.78.78.1% not ageable8.11.28.78.1NGS0.60.6  No match

     

2.30.64.12.3age 68.79.314.09.9age 558.162.254.150.6age 422.126.219.229.1age 3

  %%%%FW scale ages

Final read comparisonsAll readersreader 3reader 2reader 12007

Age Difference Plots indicate no bias between readers, Avg Percent Error (APEj) of 4.4% and CVj(APE) of 5.8% indicate relative precision of age estimates

from: Campana, et al., 1995. Graphical and statistical methods for determining the consistency of age determinations. Trans. Amer. Fish. Soc. 124: 131-138

Sitkoh Project- freshwater scale ageingSitkoh Project- freshwater scale ageing

2003 brood year = 1.4 smolt per spawner (each years’ FW age)

2.6 smolt per spawner (using average FW Age)

0.030.120.470.270.012878559averages

0.020.090.580.220.001,691*4222007

0.120.210.370.030.003,5613862006

0.010.150.580.240.002,2305382005

0.000.060.400.480.023,7427642004

0.010.110.400.380.043,1666792003

Age 6Age 5Age 4Age 3Age 2Smolt

ProductionAdult

EscapementYear

* maybe an incomplete count, due to cold spring water temps, early weir removal

Sitkoh Ck ProjectSitkoh Ck Project - 2007 PIT-tagged smolt returns- 2007 PIT-tagged smolt returns

Tag failure (4 tags)

1 ocean

2 ocean

3 ocean / 1 repeat

Total tagged smolt

2 ocean / 1 repeat

3 ocean

2 ocean / 1 skip / 1 repeat

4 ocean

0.9%

0.2

18.2

4.7

63.3%

3.1

33.2

0.5

2.4

% return in 2007OCEAN AGES

2005 smolts18.2% (77)

2006 smolts 0.02% (1)

2004 smolts36.3% (153)

2003 smolts7.6% (32)

Sitkoh Ck Project- Adult scale ageingSitkoh Ck Project- Adult scale ageing Adult scale ageingAdult scale ageing

Sitkoh Ck known ocean-ages as proxy/ageing Sitkoh Ck known ocean-ages as proxy/ageing validationvalidation

Useful for other SE Alaska projects needing Useful for other SE Alaska projects needing scale agesscale ages

Prelim. accuracy estimatePrelim. accuracy estimate 2006 recaps (n=152)2006 recaps (n=152) 1 scale aging technician1 scale aging technician Triplicate reads of each scale, 2 of 3 reads Triplicate reads of each scale, 2 of 3 reads

matchingmatching 17.8% no match17.8% no match 83.1% correct compared to known ocean 83.1% correct compared to known ocean

ages of returning smoltsages of returning smolts Need 2 addnl triplicate reads & Need 2 addnl triplicate reads &

recaps in 2007recaps in 2007

For the 2003-2007 period:For the 2003-2007 period: Adult escapement:Adult escapement: 395 – 758 395 – 758 (65% female)(65% female) Smolt outmigration: Smolt outmigration: 1,691 and 3,7421,691 and 3,742 Survival following spawn: Survival following spawn: 75%75% PIT tagging success:PIT tagging success: 76% of run in 200776% of run in 2007 Scale ageing estimates:Scale ageing estimates:

FW methods repeatable, but maybe biasedFW methods repeatable, but maybe biased SW methods repeatable and accurateSW methods repeatable and accurate

smolts per spawner:smolts per spawner: 1.4 to 2.61.4 to 2.6 adults to adults:adults to adults: 91 adults from 2003 adults91 adults from 2003 adults

(2-freshwater, 2-ocean based on scale ageing)(2-freshwater, 2-ocean based on scale ageing)

Sitkoh Ck weir Project-Sitkoh Ck weir Project- conclusions conclusions

Questions?Questions?

Funding for this project came from the U.S. Fish and Wildlife Funding for this project came from the U.S. Fish and Wildlife Service’s Federal Aid in Sport Fish Restoration Act, with matching Service’s Federal Aid in Sport Fish Restoration Act, with matching funds coming from the State of Alaska’s Fish and Game Fund. funds coming from the State of Alaska’s Fish and Game Fund.

We would also like to acknowledge the following staff: Bob We would also like to acknowledge the following staff: Bob Chadwick, Dale Brandenburger, Lee Close, Dirk Middleton, Rich Chadwick, Dale Brandenburger, Lee Close, Dirk Middleton, Rich Didrickson, Rob Pettett, Anthony Crupi, Peter Bangs, Kurt Kondzela, Didrickson, Rob Pettett, Anthony Crupi, Peter Bangs, Kurt Kondzela, Carol Coyle, Randy Mullen, Judy Lum, Carrie Hoover, Jennifer Stahl, Carol Coyle, Randy Mullen, Judy Lum, Carrie Hoover, Jennifer Stahl, Troy Tydingco, Heather Riggs, Jason Shull, Keith Pahlke, Rocky Troy Tydingco, Heather Riggs, Jason Shull, Keith Pahlke, Rocky Holmes, Brian, Frenette, Dick Callahan, Alex Blaine, Brian Glynn, Holmes, Brian, Frenette, Dick Callahan, Alex Blaine, Brian Glynn, Jeff Nichols, Jason Haas, Jarrod Sowa, Shawn Johnson, Kercia Jeff Nichols, Jason Haas, Jarrod Sowa, Shawn Johnson, Kercia Schroeder, Monica Matz, Tom Brookover, Kevin Brownlee, Mark Schroeder, Monica Matz, Tom Brookover, Kevin Brownlee, Mark Schwan, Christine Schmale, David Gregovich, Doug Fleming. Schwan, Christine Schmale, David Gregovich, Doug Fleming.

Also thanks to Roger Harding, John Der Hovanisian, Mark Schwan, Also thanks to Roger Harding, John Der Hovanisian, Mark Schwan, Dan Reed, and Randall Mullen who provided planning, analytical and Dan Reed, and Randall Mullen who provided planning, analytical and editorial support.editorial support.

AcknowledgementsAcknowledgements