History and Current Conditions at Blue Mesa Reservoir Powerpoint
Blue Mesa Fisheries Update
Dan Brauch and Adam Hansen Colorado Parks and Wildlife December 18-19, 2019 Blue Mesa Fish Update BMR fishery Kokanee management Lake trout management Lake trout harvest incentive Blue Mesa Fishery Goals
Goal #1: Provide Blue Mesa anglers with best fishing opportunities for kokanee, rainbow trout, trophy lake trout and brown trout.
Goal #2: Maintain Blue Mesa as source of kokanee eggs to provide kokanee fishing opportunities at 28 lakes in Colorado. Blue Mesa Reservoir Fisheries Supports up to 450,000 hours of angling annually. “Destination” Fishery—Up to 2/3 of anglers are from Colorado’s East Slope or from out of state Gross economic estimated to be $12.3 million in today’s dollars ($5.43 million in 1987). Curecanti NRA was responsible for an estimated $44 million in economic value in 2014. Kokanee and Lake Trout
Kokanee & lake trout are not co-evolved Lake trout stocked in Colorado in late 1800’s, Kokanee in 1951 Blue Mesa Kokanee • Stocked after Blue Mesa Dam completed (1965) with Granby source (Flathead L, MT 1951-1957) • Currently states primary egg source—natural reproduction is minimal in Colorado Kokanee Spawntake Totals by Water 2000-2019 18 Antero 16 Blue Mesa 14 Cheesman
12 Eleven Mile
10 Granby / Shadow Mt. 8 McPhee
6 Lake Nighthorse 4 Egg Total in Millions EggTotal Vallecito
2 Williams Fork 0 Wolford
Year Kokanee Fishing
Kokanee Contribution to Blue Mesa Catch May through October 100%
90%
80%
70%
60%
50%
40%
30%
20%
Kokanee percent of total catch 10%
0%
Year Kokanee Grow Trophy Trout Stable Isotope proportion of MAC diet 2010 (CSU)
100%
80% Invertebrates 60% Crayfish Perch 40% Rainbow Trout Diet Proportion Kokanee 20%
0% age 3 age 4-6 age 7-25 (12-16”) (17-23”) (24-44”) MAC Age Sonar transects
2002
2009 Sonar Estimates 1994-2019 Lake Trout Management / Regulations • Late 1980’s 1 fish over 20 inches (86-87) • 1990-1995 22-34 inch fish must be returned (slot) • 1996-2010 8 fish bag limit • 2009- 2011 CPW netting to reduce predation AND reduce reproductive capacity • 2011- 1 fish over 38 inches, unlimited under 38 • 2012-2017 CPW netting to reduce predation (reduced length target: 32” to 30” to 28”) • 2016- 1 fish over 32 inches, unlimited under 32 Lake Trout Abundance Predatory Lake Trout Abundance Lake Trout Management 2020
• Goal 1: Manage predation on kokanee to maintain kokanee fishing, eggtake and prey availability for trophy lake trout • Goal 2: Provide quality opportunities for trophy lake trout 2 Tools: Angler harvest and CPW netting 300 Angler Catch 2009-2012 250 200 150 100 50 0 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43
Angler Returned 09-12 Angler Harvested 09-12 3000 Netting Catch 2009-2019 2500 Incidental mortality a 2000 concern 1500 1000 500 0 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 Netting Removal Incidental Mortality Netting Released Lake Trout Harvest 1996-2018
Netting Catch 2009-2019 Not popular Incidental mortality a concern Kokanee VS Lake Trout Abundance Lake Trout Harvest Incentive Proposal
• Only incentivize harvest up to 24 inches: • Consume the most kokanee • 96 percent of lake trout removed by CPW AND of lake trout kept by anglers are 24 inches and smaller. • 83 percent of released lake trout under 24 inches • Harvest about 30%, far below unsustainable levels, so significantly more harvest can occur (>50%-55% continued harvest would likely be unsustainable) • Population monitoring and modelling will guide program (creel, sonar, SPIN lake trout study) to insure moving towards goals. Lake Trout Harvest Incentive Proposal
• Only heads accepted from fish under 24 inches • Dropped off at CPW offices (Gunnison and Montrose) and Blue Mesa? • Propose 2020 contest February through July • Prizes for: • Most lake trout turned in ($1000, $500, $250??) • Turned in coded wire tagged fish (propose $250 per tagged fish) • Randomly selected (one chance per head turned in) 20 $200 prizes • Other donated prizes? Blue Mesa Recommendations
• Continue stocking 3.5 million kokanee annually Blue Mesa Recommendations • Maintain kokanee survival by managing lake trout population/predation through angler harvest; achievable at Blue Mesa? • Resume netting if angling harvest is shown to not control population growth; minimize netting Blue Mesa Recommendations
• Assess lake trout management annually and provide recommendations for changes • Maintain kokanee, brown trout, rainbow trout and trophy lake trout angling opportunities • Monitor gill lice to assess effect on kokanee fishery