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

1. Steelhead Trout Production Studies at Sitkoh Creek, Southeast Alaska, 2003 – 2007 PIT-tagging, digital scale imaging/ageing & brood-tables Dave Love

2. Figure 2. Location of the weir site on Sitkoh Creek.

3. Sitkoh Ck Project- objectives and goals Objectives • Adult steelhead & steelhead smolts: counts, PIT tagging, ASL • Steelhead parr: minnow trapping for age and length data • Cutthroat, rainbow trout and Dolly Varden char: counts, length frequencies Goal: Define minimum # to fully seed habitat • Smolt per spawner index, brood-table reconstruction • Smolt per useable habitat estimate – habitat project • Expansion factor estimates - snorkel surveys

4. Sitkoh Ck - upstream and downstream traps

5. Sitkoh Ck Project - PIT tagging

6. Sitkoh Ck Project - PIT tagging

7. Sample year 2003 2004 2005 2006 2007 ADULT IMMIGRATION # upstream 672 758 538 395 422 1) Mean length (mm FL) 751 740 753 749 742 Length range (mm FL) 555 - 910 576 - 930 550 - 935 548-923 465-915 % Male 38% 39% 33% 35% 34% % Female 62% 61% 67% 65% 66% ADULT EMIGRATION # downstream 460 555 363 292 345 % survival to kelt 68% 73% 67% 76% 82% Number untagged 6 5 5 9 24 SMOLT EMIGRATION # downstream 3,166 3,742 2,230 3,561 1,691 2) Sitkoh Creek Weir – counts, sex ratios, lengths 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

8. Sitkoh Ck Project – digital scale imaging Leica DMD108 electronic microscope Screen Scan Microfiche & ScanPro software

9. Sitkoh Ck Project- freshwater scale ageing • Develop method based on common scale characteristics • Sitkoh Ck = spring spawning life-history • Freshwater and marine components to scale • Known ocean ages from PIT tagging • Electronic images made & archived • Freshwater ages –triplicate reads, multiple readers, read repeatability, paired scale & otolith comparisons

10. Sitkoh Project- freshwater scale ageing Final read comparisons All readers 2007 reader 1 reader 2 reader 3 FW scale ages % % % % age 3 29.1 19.2 26.2 22.1 age 4 50.6 54.1 62.2 58.1 age 5 9.9 14.0 9.3 8.7 age 6 2.3 4.1 0.6 2.3 No match 0.6 0.6 NGS 8.1 8.7 1.2 8.1 % not ageable 8.1 8.7 1.7 8.7 % repeatability 91.9 91.3 98.3 91.3 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

11. Sitkoh Project- freshwater scale ageing Year Adult Escapement Smolt Production Age 3 Age 4 Age 5 Age 6 Age 2 2003 679 3,166 0.04 0.38 0.40 0.11 0.01 2004 764 3,742 0.02 0.48 0.40 0.06 0.00 2005 538 2,230 0.00 0.24 0.58 0.15 0.01 2006 386 3,561 0.00 0.03 0.37 0.21 0.12 2007 422 1,691* 0.00 0.22 0.58 0.09 0.02 averages 559 2878 0.01 0.27 0.47 0.12 0.03 * maybe an incomplete count, due to cold spring water temps, early weir removal 2003 brood year = 1.4 smolt per spawner (each years’ FW age) 2.6 smolt per spawner (using average FW Age)

12. % return in 2007 2.4 4.7 2003 smolts 7.6% (32) 0.5 33.2 2004 smolts 36.3% (153) 3.1 18.2 2005 smolts 18.2% (77) 0.2 2006 smolts 0.02% (1) 0.9% 63.3% Sitkoh Ck Project- 2007 PIT-tagged smolt returns OCEAN AGES 4 ocean 3 ocean / 1 repeat 2 ocean / 1 skip / 1 repeat 3 ocean 2 ocean / 1 repeat 2 ocean 1 ocean Tag failure (4 tags) Total tagged smolt

13. Sitkoh Ck Project- Adult scale ageing • Adult scale ageing • Sitkoh Ck known ocean-ages as proxy/ageing validation • Useful for other SE Alaska projects needing scale ages Prelim. accuracy estimate • 2006 recaps (n=152) • 1 scale aging technician • Triplicate reads of each scale, 2 of 3 reads matching • 17.8% no match • 83.1% correct compared to known ocean ages of returning smolts • Need 2 addnl triplicate reads & recaps in 2007

14. Sitkoh Ck weir Project- conclusions For the 2003-2007 period: • Adult escapement: 395 – 758 (65% female) • Smolt outmigration: 1,691 and 3,742 • Survival following spawn: 75% • PIT tagging success: 76% of run in 2007 • Scale ageing estimates: • FW methods repeatable, but maybe biased • SW methods repeatable and accurate • smolts per spawner: 1.4 to 2.6 • adults to adults: 91 adults from 2003 adults (2-freshwater, 2-ocean based on scale ageing)

15. Questions?

16. Acknowledgements Funding for this project came from the U.S. Fish and Wildlife Service’s Federal Aid in Sport Fish Restoration Act, with matching funds coming from the State of Alaska’s Fish and Game Fund. We would also like to acknowledge the following staff: Bob Chadwick, Dale Brandenburger, Lee Close, Dirk Middleton, Rich Didrickson, Rob Pettett, Anthony Crupi, Peter Bangs, Kurt Kondzela, Carol Coyle, Randy Mullen, Judy Lum, Carrie Hoover, Jennifer Stahl, Troy Tydingco, Heather Riggs, Jason Shull, Keith Pahlke, Rocky Holmes, Brian, Frenette, Dick Callahan, Alex Blaine, Brian Glynn, Jeff Nichols, Jason Haas, Jarrod Sowa, Shawn Johnson, Kercia Schroeder, Monica Matz, Tom Brookover, Kevin Brownlee, Mark Schwan, Christine Schmale, David Gregovich, Doug Fleming. Also thanks to Roger Harding, John Der Hovanisian, Mark Schwan, Dan Reed, and Randall Mullen who provided planning, analytical and editorial support.