Population Demographics of Silver Carp in a Large Mesotrophic Reservoir Allison (DeRose) Lebeda, Timothy Spier, Neal Jackson Upper Midwest Invasive Species Conference La Crosse, WI Oct. 16-19, 2016
Background: Hypophthalmichthys molitrix Silver Carp are an exotic planktivore from Eastern Asia. Kolar et al. 2005 Silver Carp were introduced in 1970s to promote water quality. Freeze and Henderson 1982; Kolar et al. 2005 Silver Carp escaped during flooding events by 1980. Freeze and Henderson 1982
Invasion of Silver Carp blueplanetsociety.blogspot.com USGS Silver Carp Distribution as of October 2016 Illinoistimes.com
Silver Carp Population Demographics in the U.S. It s crucial to understand population demographics of Silver Carp to: Predict impacts on native species Evaluate control strategies Others have described population demographics for Midwestern rivers. Until recently, no one had looked at a Silver Carp population in a large reservoir. Mississippi River Illinois River Wabash River
Kentucky Lake Largest reservoir in the eastern United States 296 km long 64,870 ha surface area at full pool Classified as mesotrophic Kerns et al. 2009, White 2014 Notable recreational and commercial fisheries Silver Carp were officially documented in 2004. USGS Non-indigenous Aquatic Species List Map Credit: Dalton Lebeda
Research Objectives Describe population metrics for Silver Carp in Kentucky Lake. Size structure Age Growth Mortality rates Spawning periodicity Compare population metrics from Kentucky Lake Silver Carp to other populations in United States rivers.
Capture Methods & Biological Data Collected Photo Credit: jasonhalfenoutdoors.com Effort: 1725 hours = 77 carp Photo Credit: Tim Spier Effort: 40 hours = 54 carp Total length Weight Effort: = 21 carp Effort: 17 trips = 289 carp Sex Gonad weight Fin ray for aging Photo Credit: aliexpress.com Photo Credit: wkms.org
Aging Using Pectoral Fin Rays Three 700 µm sections cut Annuli illuminated using reflected light 2 independent readers Consensus annuli agreed upon if ages differed Statistical Analyses Growth modeled using von Bertalanffy curve Mortality estimated using weighted catch curve regression Gonadosomatic Index (GSI) = 100*(gonad weight/body weight)
Results: Size Structure in Kentucky Lake 150 150 n = 441 February 2015 September 2016 150 100 100 Frequency 100 Gear angler cast net electroshocking gill nets Frequency 50 Frequency Gear an ca ele gil 50 50 0 0 200 400 600 800 1000 1200 Mean Total Length (mm) 0 0 200 400 600 800 1000 1200 Mean Total Length (mm) 0 0 200 400 600 800 1000 1200 Mean Total Length (mm)
Results: Size Structure Percent Frequency 150 Kentucky Lake Other Populations 30 20 10 Wabash River N = 126 Frequency 100 50 30 20 10 30 20 10 Illinois River N = 203 Middle Mississippi River N = 100 Illinois River N = 203 0 0 200 400 600 800 1000 1200 Mean Total Length (mm) 200 300 400 500 600 700 800 900 Length Groups (mm) Ammended from Seibert et al. 2015
Results: Length-Weight Relationship Kentucky Lake Log10(weight) = -12.39+3.15log10(length) Other Populations Log10 Weight (g) 2 4 6 8 4.5 5.0 5.5 6.0 6.5 7.0 Log10 Total Length (mm) n = 439 R 2 = 0.99 Ammended from Hayer et al. 2014
Results: Growth in Kentucky Lake l t = 912 (1 e -0.8849 (t (0.6630)) ) Total Length (mm) 0 200 400 600 800 1000 1200 n = 173 2 4 6 8 10 Age (yrs)
Results: Growth in Kentucky Lake Juvenile Silver Carp July 2015 to July 2016 April 2016 to August 2016 400 400 Mean Total Length (mm) 300 200 100 Mean Total Length (mm) 300 200 100 Photo Credit: Dalton Lebeda 0 2015 2016 Year 0 April May June July August Month
Results: Growth Other Populations
Results: Mortality Rate in Kentucky Lake 2015 only Other Populations Ln(Frequency) 0 1 2 3 4 n = 133 R 2 = 0.797 P-value = <0.005 Age (yrs) Z=0.762 A=53.3% 4 6 8 10 Middle Mississippi River: 63% Seibert et al. 2015 Illinois River: 63.3% Stuck et al. 2015 Wabash River: 43.6% Stuck et al. 2015
Results: Spawning Periodicity n = 319
Summary Describe and compare population metrics for Silver Carp in Kentucky Lake to other populations. Size structure MUCH LARGER Age COMPARABLE Growth MUCH FASTER Mortality rates LOWER These metrics represent population demographics of a fairly recent invasion in a large reservoir.
Current and Future Research We don t know if the population characteristics seen in Silver Carp in Kentucky Lake are because of an early invasion or a large reservoir. KDFWR is developing a long term sampling effort to monitor trends in abundance and population metrics. We don t know how much immigration is contributing to the reservoir s population. We are conducting a telemetry study to follow movements of Silver Carp. Photo Credit: Brad Hartman
Acknowledgements Field Help: Dalton Lebeda Jessica Morris Brad Hartman Ronnie Hopkins Brad Richardson Clint Cunningham Nathan Ward Ben Tumolo Matt May Alex Vaisvil Christy Soldo Nathan Tillotson Josh Revell Project Funding: Graduate Innovation Assistantship Hattie Mayme Ross Scholarship Larry D. Pharris Memorial Wildlife Fund Scholarship Dr. Morgan Emory Sisk Jr. Memorial Scholarship Watershed Studies Research Institute Grants Jesse D. Jones College of Science, Engineering and Technology Travel Grants