Stock Assessment of Winter Steelhead Trout in Goldstream, Sooke, Trent and Tsable Rivers, 2004 by: Scott Silvestri Fisheries Technician BC Conservation Foundation Greater Georgia Basin Steelhead Recovery Plan prepared for: British Columbia Conservation Foundation #206-17564 56A Surrey, BC V3S 1G5 and: Ministry of Water, Land and Air Protection Vancouver Island Region 2080-A Labieux Road Nanaimo, BC V9T 6J9 December 2005 Stock Assessment of Winter Steelhead Trout in Goldstream, Sooke, Trent and Tsable Rivers, 2004 ii ACKNOWLEDGEMENTS British Columbia Conservation Foundation staff including Adri Bigsby, James Craig, Mike McCulloch, Kevin Pellett, Brad Smith, Harlan Wright and the author conducted snorkel surveys and/or juvenile standing stock assessments in the four rivers examined. Additional snorkel survey support from Tony Massey1 and Ron Ptolemy2 was much appreciated. Additionally, Ron Ptolemy provided valuable stock assessment data. Thanks are also extended to Craig Wightman3 who was key in initiating this project and acted as scientific authority. Appreciation is extended to James Craig for editing this report. Funding for this project was provided by the BC Conservation Foundation through a Ministry of Water, Land and Air Protection grant for the development of recreational hunting and fishing opportunities in British Columbia. 1 Fish Culture Technician, Freshwater Fisheries Society of BC, Duncan, BC 2 Standards/Guidelines Specialist, Ministry of Environment, Victoria, BC 3 A/Manager, Salmon and Steelhead Recovery, Ministry of Environment, Nanaimo, BC ________________________________________________________________________________________________ British Columbia Conservation Foundation Greater Georgia Basin Steelhead Recovery Plan Stock Assessment of Winter Steelhead Trout in Goldstream, Sooke, Trent and Tsable Rivers, 2004 iii TABLE OF CONTENTS 1.0 INTRODUCTION ............................................................................................................. 1 1.1 Goldstream River........................................................................................................1 1.2 Sooke River................................................................................................................2 1.3 Trent River..................................................................................................................3 1.4 Tsable River................................................................................................................3 2.0 METHODS.........................................................................................................................4 2.1 Adult Assessment.......................................................................................................4 2.2 Juvenile Assessment...................................................................................................5 3.0 RESULTS........................................................................................................................... 5 3.1 Goldstream River........................................................................................................5 3.2 Sooke River................................................................................................................9 3.3 Trent River................................................................................................................13 3.4 Tsable River..............................................................................................................16 4.0 DISCUSSION................................................................................................................... 20 4.1 Goldstream River......................................................................................................21 4.2 Sooke River..............................................................................................................23 4.3 Trent River................................................................................................................25 4.4 Tsable River..............................................................................................................26 5.0 SUMMARY AND CONCLUSIONS.............................................................................. 27 6.0 REFERENCES ................................................................................................................ 29 ________________________________________________________________________________________________ British Columbia Conservation Foundation Greater Georgia Basin Steelhead Recovery Plan Stock Assessment of Winter Steelhead Trout in Goldstream, Sooke, Trent and Tsable Rivers, 2004 iv LIST OF FIGURES Figure 1. Location of Goldstream, Sooke, Trent and Tsable rivers, Vancouver Island. ................ 1 Figure 2. Goldstream River watershed, with the anadromous falls, electrofishing sites and snorkel survey area illustrated. ...................................................................................... 6 Figure 3. Steelhead counts versus run timing for the Goldstream River, February 4 – May 20, 2004............................................................................................................................... 7 Figure 4. Uncorrected average daily discharge readings of the Goldstream River above Japan Gulch Reservoir from January 1 – May 31, 2004. ........................................................ 8 Figure 5. Non depth/velocity adjusted steelhead fry densities from four electrofishing sites in the Goldstream River in 2004. ............................................................................................ 8 Figure 6. Length-frequency distribution of juvenile steelhead sampled from four sites in the Goldstream River in 2004. ............................................................................................ 9 Figure 7. Sooke River watershed, with the anadromous falls, electrofishing sites, and snorkel survey area illustrated.................................................................................................. 10 Figure 8. Steelhead counts versus run timing for the Sooke River, January 6 – May 21, 2004... 11 Figure 9. Uncorrected average daily discharge readings of the Sooke River below the Sooke Potholes parking lot. January 1 – May 31, 2004. ....................................................... 12 Figure 10. Non depth/velocity adjusted steelhead fry densities from six electrofishing sites in the Sooke River in 2004. ................................................................................................... 12 Figure 11. Length-frequency distribution of juvenile steelhead sampled from six sites in the Sooke River in 2004. ................................................................................................... 13 Figure 12. Trent River watershed, with the anadromous barrier, electrofishing sites, and snorkel survey area illustrated.................................................................................................. 14 Figure 13. Steelhead counts versus run timing for the Trent River, January 26 – May 25, 2004. 14 Figure 14. Non depth/velocity adjusted steelhead fry densities from six electrofishing sites in the Trent River in 2004. .................................................................................................... 15 Figure 15. Length-frequency distribution of juvenile steelhead sampled from six sites in the Trent River in 2004. .............................................................................................................. 16 Figure 16. Tsable River watershed, with the anadromous falls, electrofishing sites, and snorkel survey area illustrated.................................................................................................. 17 Figure 17. AUC results for snorkel survey series in the Tsable River, January 26 – May 25, 2004. ..................................................................................................................................... 17 Figure 18. Corrected average daily discharge for the Tsable River above the trestle bridge, January 1 – May 31, 2004 (WSC data). ...................................................................... 18 Figure 19. Non depth/velocity adjusted steelhead fry densities from six electrofishing sites in the Tsable River in 2004. .................................................................................................. 19 Figure 20. Length-frequency distribution of juvenile steelhead sampled from six sites in the Trent River in 2004. .............................................................................................................. 20 Figure 21. Steelhead Harvest Analysis data for the Goldstream River, 1968 – 1998.. ................ 22 Figure 22. Peak adult steelhead densities (fish/km) observed during snorkel surveys of the Goldstream River, 1998-2004. .................................................................................... 22 ________________________________________________________________________________________________ British Columbia Conservation Foundation Greater Georgia Basin Steelhead Recovery Plan Stock Assessment of Winter Steelhead Trout in Goldstream, Sooke, Trent and Tsable Rivers, 2004 v Figure 23. Non depth/velocity adjusted fry densities from the Goldstream River in 2004 (four sites) and 2001 (two sites). Geometric means for each year are also shown.............. 23 Figure 24. Steelhead Harvest Analysis data for the Sooke River, 1968-2004.............................