Lahontan Cutthroat Program Lahontan National Fish Hatchery Complex US Fish and Wildlife Service

Tahoe Working Group Meeting February 16, 2010 Presentation Outline

¾ Lahontan –Background

¾ LCT reintroduction in Fallen Leaf using adaptive management strategies

¾ Assessment –A Tahoe Legacy

¾ The only trout native to the basin ¾ Provided extensive recreational and commercial fisheries ¾ Extirpated from the basin in the 1930’s Pilot Peak LCT ¾ Represents the original Tahoe Basin strain based on genetic comparisons with museum specimens ¾ Exhibits ancestral life history characteristics Conservation and Recovery Efforts

¾ Recovery Plan in 1995 ¾ Short‐term Action Plans for Walker and Truckee Basins 2003 ¾ Formation of Tahoe Basin Recovery Implementation Team 2007 ¾ Recovery Implementation Plan 2010 Research 2002‐2005 (FWS,UCD,UNR,UW)

¾ Stunted indicate resource limited system

¾ High shore angler catch rate of LCT

¾ Significant lake trout predation on stocked LCT

¾ Full compliment of native zooplankton species Fallen Leaf Lake Research 2007 (FWS,UNR)

¾ Refined lake trout abundance estimate: 8,799 lake trout (Schnabel) 95% CI = 4,990 –16,530

¾ Identification of refugia from predation for LCT z Thermocline segregation z LCT refuge in woody debris

¾ Diet of lake trout dependent on size and time of year Adaptive management at Fallen Leaf Lake ¾ The challenges

z Lake trout

z Mysid shrimp

z Over fishing ¾ The strategy

z Improve stocking methods

z Research lake trout removal methods

z Monitor ecosystem effects of management actions Adaptive Management Implementation 2008 and 2009

¾ Remote Site Incubation

¾ Adaptive Stocking Methods

¾ Hydroacoustic Detection of Lake Trout

¾ 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 ¾ 4 incubators for both years z 3,500 per incubator 2008 z 7,500 per incubator 2009 Down stream monitoring

¾ Fry released z 2008 – 7,000 z 2009 – 20,000 Juvenile Stocking Strategy

¾ Implemented in 2008 • Stocked over 60,000 4‐6 “ fish ¾ Thermocline • June‐October ¾ Dispersion • Released at 11 Sites ¾ Refugia Adult Stocking Strategy

¾ Implemented in 2009 • Stocked over 30,000 10” fish

¾ Thermocline • June‐October

¾ Dispersion • Released at 5 different sites over 5 days

¾ Refugia 2009 Adaptive Management Objectives

¾ Enhance the recreational fishery at Fallen Leaf Lake by stocking LCT

¾ Refine Lake trout netting methods to reduce incidental catch of fishes native to the Tahoe basin

¾ Test the feasibility of systematic removal of lake trout Percentage of Anglers Interviewed Reporting Fishing Success

90.0%

80.0% success

70.0% Catchable LCT stocked before creel 60.0% survey fishing

50.0% Year without 40.0% stocking catchable LCT 30.0%

20.0%

10.0% Anglers reporting 0.0% % 2002 2003 2004 2005 2006 2007 2008 2009 Year Primary Angler Catch Stocking vs. Non‐stocking Years 2008 Creel 2009 Creel KOK RBT BT MWF KOK RBT

Lake trout

Lake Trout LCT 61% 97%

n = 73 Number of fish caught per angler shore fishing

4 Catchable LCT 3.5 stocked

3 No catchables Caught stocked 2.5 Fish of

2

1.5 number

1 Average 0.5

0 2002 2003 2004 2005 2006 2007 2008 2009 Creel Census Year 2009 LCT Initial Survival Predation vs. Angler Catch Rate

3 1.400 Number of LCT per lake trout Number of LCT caught per angler 1.200 2.5

1.000

2 0.800

1.5 0.600

0.400 1

0.200

0.5 0.000

0 0.200 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 LCT Diet Locating lake trout with hydroacoustics to increase netting efficiency Lake Trout Specific Gill Nets

Native non‐game fishes

3%

95% Lake Trout (2% other non‐native trout) Lake trout donations to South Lake Tahoe food bank Summary for Adaptive Management Actions

¾ Improved remote site incubation ¾ Successful stocking program

z Larger fish

z Stocked during thermocline

z Not tagged ¾ Improved recreational fishery ¾ Lake trout specific netting methods

z 4” mesh

z During fall spawning ¾ Donation of lake trout filets to local food bank Lake Tahoe Strategies ¾ Use the methods and tools refined at Fallen Leaf Lake to guide initial strategies in Lake Tahoe for assessment and reintroduction ¾ Select 2‐5 Lake Tahoe streams/tributaries and areas within Tahoe for LCT recovery/reintroduction ¾ Provide LCT production at levels to support harvest and recreational fishing in Lake Tahoe Questions/Comments