Lahontan Cutthroat Trout Program Lahontan National Fish Hatchery Complex us fish and Wildlife Service Tahoe Working Group Meeting February 16, 2010
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Lahontan Cutthroat Trout Program Lahontan National Fish Hatchery Complex US Fish and Wildlife Service Tahoe Working Group Meeting February 16, 2010 Presentation Outline Lahontan cutthroat trout – Background LCT reintroduction in Fallen Leaf Lake using adaptive management strategies Lake Tahoe Assessment Lahontan cutthroat trout – A Tahoe Legacy The only trout native to the basin Provided extensive recreational and commercial fisheries Extirpated from the basin in the 1930’s Pilot Peak LCT Represents the original Tahoe Basin strain based on genetic comparisons with museum specimens Exhibits ancestral life history characteristics Conservation and Recovery Efforts Recovery Plan in 1995 Short‐term Action Plans for Walker and Truckee Basins 2003 Formation of Tahoe Basin Recovery Implementation Team 2007 Recovery Implementation Plan 2010 Fallen Leaf Lake Research 2002‐2005 (FWS,UCD,UNR,UW) Stunted lake trout indicate resource limited system High shore angler catch rate of LCT Significant lake trout predation on stocked LCT Full compliment of native zooplankton species Refined lake trout abundance estimate: 8,799 lake trout (Schnabel) 95% CI = 4,990 – 16,530 Identification of refugia from predation for LCT Thermocline segregation LCT refuge in woody debris Diet of lake trout dependent on size and time of year Fallen Leaf Lake Research 2007 (FWS,UNR) Adaptive management at Fallen Leaf Lake The challenges Lake trout Mysid shrimp Over fishing The strategy Improve stocking methods Research lake trout removal methods Monitor ecosystem effects of management actions Adaptive Management Implementation 2008 and 2009 Remote Site Incubation Adaptive Stocking Methods Hydroacoustic Detection of Lake Trout Lake trout abundance estimation: 15,675 lake trout (Peterson) 95% CI = 9,564 – 27,086 GLEN ALPINE CREEK Remote Site Incubation Remote Site Incubation Results 2008 and 2009 4 incubators for both years 3,500 per incubator 2008 7,500 per incubator 2009 Fry released 2008 – 7,000 2009 – 20,000 Down stream monitoring Juvenile Stocking Strategy Implemented in 2008 •
Thermocline •
Dispersion •
Refugia Adult Stocking Strategy Implemented in 2009 •
10” fish Thermocline •
Dispersion •
sites over 5 days Refugia 2009 Adaptive Management Objectives Enhance the recreational fishery at Fallen Leaf Lake by stocking LCT Refine Lake trout netting methods to reduce incidental catch of fishes native to the Tahoe basin Test the feasibility of systematic removal of lake trout 0.0% 10.0%
20.0% 30.0%
40.0% 50.0%
60.0% 70.0%
80.0% 90.0%
2002 2003
2004 2005
2006 2007
2008 2009
% Anglers reporting fishing success Year Percentage of Anglers Interviewed Reporting Fishing Success Catchable LCT stocked before creel survey Year without stocking catchable LCT Lake Trout 97% KOK RBT BT MWF 2008 Creel n = 73
2009 Creel Lake trout LCT 61% Primary Angler Catch Stocking vs. Non‐stocking Years 0 0.5
1 1.5
2 2.5
3 3.5
4 2002
2003 2004
2005 2006
2007 2008
2009 Av e ra g e number of Fish Caught Creel Census Year Number of fish caught per angler shore fishing Catchable LCT stocked No catchables stocked 0.200 0.000
0.200 0.400
0.600 0.800
1.000 1.200
1.400 0 0.5 1 1.5
2 2.5
3 7/26/2009 7/31/2009 8/5/2009
8/10/2009 8/15/2009 8/20/2009 8/25/2009 8/30/2009 9/4/2009
Date Number of LCT caught per angler Number of LCT per lake trout 2009 LCT Initial Survival Predation vs. Angler Catch Rate LCT Diet Locating lake trout with hydroacoustics to increase netting efficiency Lake Trout Specific Gill Nets 3% 95% Lake Trout ( 2% other non‐native trout ) Native non‐game fishes Lake trout donations to South Lake Tahoe food bank Summary for Adaptive Management Actions Improved remote site incubation Successful stocking program Larger fish Stocked during thermocline Not tagged Improved recreational fishery Lake trout specific netting methods 4” mesh During fall spawning Donation of lake trout filets to local food bank Lake Tahoe Strategies Use the methods and tools refined at Fallen Leaf Lake to guide initial strategies in Lake Tahoe for assessment and reintroduction Select 2‐5 Lake Tahoe streams/tributaries and areas within Tahoe for LCT recovery/reintroduction Provide LCT production at levels to support harvest and recreational fishing in Lake Tahoe Questions/Comments Document Outline
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