Context For Conservation and Management of Eutsuk Lake Rainbow Trout prepared by: Joseph S. De Gisi Box 2518 Smithers, BC V0J 2N0 for: BC Parks Skeena District Bag 5000 Smithers, BC V0J 2N0 March 21, 2003 Context for Management of Eutsuk Lake Rainbow Trout Table of Contents Introduction.........................................................................................................1 1.1. Information Sources ....................................................................................................2 2. Biology and Assessment of Pelagic Piscivorous Rainbow Trout................3 2.1. Rainbow Trout Production Characteristics ..............................................................3 2.2. Lake Physiochemistry Related to Fish Production...................................................3 2.3. Kokanee Production ....................................................................................................4 2.4. Pelagic Piscivorous Rainbow Trout Life History......................................................5 2.5. Reproductive Habitat ..................................................................................................6 2.6. Pelagic Piscivorous Rainbow Trout Abundance Assessment ................................12 2.6.1. Adult Enumeration in Lakes ................................................................................12 2.6.2. Adult Enumeration in Streams.............................................................................13 2.6.3. Fry and Juvenile Enumeration in Streams ...........................................................16 2.7. Recommended Actions and Costs.............................................................................17 2.7.1. Angling Use Survey.............................................................................................18 2.7.2. Anchor-Tagging Program ....................................................................................19 2.7.3. Temperature Data Collection...............................................................................19 2.7.4. Population Genetic Analyses ...............................................................................19 2.7.5. Juvenile Habitat/Abundance Survey....................................................................20 2.7.6. Kokanee Hydroacoustic Assessment ...................................................................20 2.7.7. Rainbow Trout Escapement Monitoring..............................................................20 2.7.8. Simulation Modeling and Analysis......................................................................21 2.8. Funding.......................................................................................................................21 2.8.1. Corporate..............................................................................................................21 2.8.2. Provincial Government ........................................................................................21 3. Angling Use....................................................................................................39 3.1. Pelagic Piscivorous Rainbow Trout Lakes ..............................................................39 3.2. Summary of Results...................................................................................................44 3.2.1. Other Issues..........................................................................................................45 3.3. Eutsuk Lake Angling Use..........................................................................................49 3.3.1. Characteristics of the Rainbow Trout Fishery .....................................................49 3.3.2. Design of An Angling Use Study ........................................................................50 4. References ......................................................................................................52 i Context for Management of Eutsuk Lake Rainbow Trout List of Figures Figure 1. Length at age for pelagic piscivorous rainbow trout populations. Lake populations shown are those for which lake surface area is greater than Eutsuk Lake..................................................................................................................................30 Figure 2. Length at age for pelagic piscivorous rainbow trout populations. Lake populations shown are those for which lake surface area is less than that of Eutsuk Lake......................................................................................................................31 Figure 3. Characteristics of streams believed used for spawning and rearing of pelagic piscivorous rainbow trout....................................................................................35 Figure 4. Annual total estimated angler hours per square kilometre of lake surface area (top panel) and annual total estimated angler days per square kilometre of lake surface area (bottom panel), for pelagic piscivorous rainbow trout recreational fishery surveys .............................................................................................47 Figure 5. Average total catch of rainbow trout per angler hour and harvest of rainbow trout per angler hour (top panel); and average total catch of rainbow trout per angler day and harvest of rainbow trout per angler day (bottom panel), for pelagic piscivorous rainbow trout recreational fishery surveys .................................48 Figure 6. Annual total number of rainbow trout harvested per square kilometre of lake surface area, for pelagic piscivorous rainbow trout recreational fishery surveys .............................................................................................................................49 Figure 7. Average daily mean discharge at stations on Khtada River, Lyre River, and Bonaparte River ..............................................................................................................76 Figure 8. Average daily mean discharge at stations on Horsefly River, Mitchell River, and McKinley Creek .............................................................................................77 Figure 9. Average daily mean discharge at stations on Bessette Creek, Duteau Creek, Scotch Creek and Eagle River .........................................................................................78 Figure 10. Average daily mean discharge at stations on Barriere River, Mission Creek, and Lardeau River. ...............................................................................................79 Figure 11. Upper panel: day of peak rainbow trout spawning count at Gerrard, Lardeau River, 1961 to 2002............................................................................................80 Figure 12. Water temperature (°C) at peak rainbow trout spawner count, Lardeau River at Gerrard, 1961 to 2002 ........................................................................................81 Figure 13. Relationship between day of year of rainbow trout spawner peak count, and the first day in which the average Lardeau River water temperature exceeded 5°C at Gerrard 1961-2002................................................................................................81 Figure 14. Upper panel: relationship between day of year of peak spawner count and the first day in which the average Lardeau River water level gauge reading exceed 1.9 at Gerrard, 1962-1982. Lower panel: relationship between day of year of peak spawner count and the first day in which the average Lardeau River water level gauge reading exceed 1.0 at Gerrard, 1983-2002..........................................82 Figure 15. Relationship between the average Lardeau River water temperature at Gerrard in the five-day period centred on the day of peak rainbow trout spawner count (horizontal axis), and the average water level at Gerrard during the same period (vertical axis). .......................................................................................................83 Figure 16. Back cover (left) and front cover (right) of Eutsuk Lake angler survey ..............86 ii Context for Management of Eutsuk Lake Rainbow Trout List of Figures (continued) Figure 17. Page 2 (left) and page 7 (right) of Eutsuk Lake angler survey booklet................87 Figure 18. Page 6 (left) and page 3 (right) of Eutsuk Lake angler survey booklet................88 Figure 19. Page 4 (left) and page 5 (right) of Eutsuk Lake angler survey booklet................89 Figure 20. "Chikamin Portage Visitors" data form to be used to record the visit and angling activity details of parties who enter and/or exit Tweedsmuir Park at Chikamin Portage.............................................................................................................90 Figure 21. Instructions for the form "Chikamin Portage Visitors". .......................................91 Figure 22. "Chikamin Interviews" data form to be used to record summaries of angling activity of anglers who enter and/or exit Tweedsmuir Park at Chikamin Portage but fail to complete a survey booklet..................................................................92 Figure 23. Instructions for the form "Chikamin Portage Interviews"....................................93 Figure 24. Data form to be used by angling lodge staff to record daily details of angling activity of guided anglers....................................................................................94 Figure 25. Instructions for the form "Guided Angler