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Charmane Ashbrook, Michael Mizell, & Ken Warheit Tomelleri.

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Presentation on theme: "Charmane Ashbrook, Michael Mizell, & Ken Warheit Tomelleri."— Presentation transcript:

1 Charmane Ashbrook, Michael Mizell, & Ken Warheit Tomelleri

2 ESA listing Sport selective fishery impacts?

3 More reasons Variable survival estimates Use a control to extricate effects of handling and tagging

4 Plan Part A, estimate survival Part B, estimate encounter rate Together, these estimates enable us to estimate the impact of sport selective fisheries on wild steelhead. Example:  Yearly escapement --1000 wild fish return  50% encounter rate --500 captured with sport gear  95 % survival rate -- 475 lived following release from sport gear  5% mortality rate --25 killed by sport gear

5 Plan Part A, estimate immediate and post-release survival Part B, estimate encounter rate Together, these estimates enable us to estimate the impact of sport selective fisheries on wild steelhead. Example:  Yearly escapement --1000 wild fish return  50% encounter rate --500 captured with sport gear  95 % survival rate -- 475 lived following release from sport gear  5% mortality rate --25 killed by sport gear

6 Plan Part A, estimate immediate and post-release survival Part B, estimate encounter rate Together, these estimates enable us to estimate the impact of sport selective fisheries on wild steelhead. Example:  Yearly escapement --1000 wild fish return  50% encounter rate --500 captured with sport gear  95 % survival rate -- 475 lived following release from sport gear  5% mortality rate --25 killed by sport gear

7 Methods Capture 30 wild winter steelhead on hook and line Capture 30 control fish Radio tag –small population, follow movement Insert tags surgically, potential iteroparity Track fish using fixed and mobile (vehicle) receivers Two year study Tag fish regardless of wounds, bleeding Collect photo, length, scale, DNA, and weight data Use GIS to track fish

8 Methods II Three parts to survival 1.Immediate : from capture until release 2.Post-release: from release until presumed spawning 3.Out-migration: from presumed spawning until out- migrate from river (kelt)

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11 Pre-season 2009: Little water problem

12 Results I Control fish (trap) 2008: 12 2009: 7 Control X fish (previously hooked) 2008: 7 2009: 1 Treatment fish (sport) 2008: 27 2009: 27

13 Estimating survival Conceptual example : Immediate + post-release = total survival by Keeley, E.R. by Keeley, E.R.

14 Results II --survival GroupImmediate survival Post-release to presumed spawning Survival Control100% Control X100% Treatment100%

15 Estimating survival--take two Conceptual example using out-migration as proxy for spawning: Immediate + post-release + out-migration = total survival

16 Results III --survival GroupKelted after spawning Sample size Survival relative to control % 90% confidence intervals 2008 Treatment172775.5651.2-99.9 2009 Treatment222795.0667.0-100.0 Average Treatment ---------- 85.31------------- 2008 Control X5785.7147.4-100.0 2009 Control X100.00------ 2008 Control1012-------------- 2009 Control67-------------- There is a cost to being captured with sport gear.

17 Results IV--age structure AgeNumber for 2008 Number for 2009 Notes 2.1+1521One fish had one spawning check (2009) 2.2+74 3.1+40One fish had one spawning check (2008) 3.2+40 R.1+105 R.2+60One fish had 2 spawning checks (2008) Samish steelhead can spawn multiple times but most spawn only once and after 1 year in saltwater.

18 Results V --Gender YearGroupLivedDiedTotal 2008Female22527 2008Male11819 2008Both331346 2009Female13215 2009Male15419 2009Both28634 2008 more females out-migrated (kelted) than males. Consistent with other studies and evolutionary theory. 2008 Chi square test p=0.08 2009 Chi square test p=0.56

19 Results VI--DNA analysis 2009 group had 5 fish with hatchery parentage 3 controls and 2 treatment 3 kelted 2 with 2.1+ age structure; 2 spawn check Feb 23 rd to Mar 28 th 2008 group had 8 fish with hatchery parentage 7 controls and 1 treatment 7 kelted 3 with 3+ age structure; 1 spawn check Feb 7 th to Mar 6 th

20 Comparison with other research Evolution of hooking mortality studies, technology & statistical improvements Recent studies California, summers, n=126 hook location & temperature >21C. 1995 & 1996. Fish observed for 36 hours. British Columbia, winters, n=226 radio tag. Tag regurgitation, no control, bleeding fish not included?

21 Conclusions There is a biological cost to sport fishing, 15% Relatively high kelting rate may be typical for this kind of stream, low gradient and near saltwater Fair % of “wild” fish had hatchery influence Despite high kelting rate, relatively few fish were > first time spawners based on scale analysis

22 Further explorations Evaluate in higher gradient, further in-river system; fish that must travel further may have a lower survival In estuary environment survival will likely be lower Estimate recapture survival Kelt migration and movement patterns in saltwater Consider if management objective to separate hatchery and wild fish based on return timing is successful Summer steelhead survival may be lower because of warmer water and longer time in freshwater Estimate encounter rate to estimate impact to population

23 Acknowledgements Samish Hatchery Crew Bob Leland & Steve Schroder Equipment: USGS, University of Idaho, & Pete Hahn Technicians: Jen Mertes, Ryan Regner, Jim Crook, Faith Sandretzky, and Kyle Gulbranson Earl Steele and his fisheries class at Bellingham Technical College; Jim Naranovich Fishermen: Brett Barkdull, Curt Kraemer, and local volunteers

24 Hook location Treatment (sport caught) 34 maxillary 1 behind eye 3 snout 1 top of head 1 no data Control X (hatchery weir, previously hooked) 6 maxillary 1 no data

25 Artificial bait Corky Eggs Float Sand shrimp Yarn Fishing gear

26 Gender 2009 GroupControlTreatmentHooked Control Female4130 Male3131 Unknown010 Both7271 2008 GroupControlTreatmentHooked Control Female8154 Male4123 Unknown000 Both12277


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