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Tuesday, January 30 • 1:40pm - 2:00pm
ASIAN CARP & OTHER AQUATIC INVASIVES: Effects of 2, 4-D Herbicide Treatments Used to Control Eurasian Watermilfoil on Fish and Zooplankton in Northern Wisconsin Lakes

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AUTHORS. Nicholas Rydell, Wisconsin Cooperative Fishery Research Unit, University of Wisconsin-Stevens Point; Daniel Isermann, U.S. Geological Survey; Justin VanDeHey, College of Natural Resources; John Kubisiak, Wisconsin Department of Natural Resources; Kevin Gauthier, Wisconsin Department of Natural Resources; Scott Van Egeren, Wisconsin Department of Natural Resources

ABSTRACT. Eurasian watermilfoil (EWM) Myriophyllum spicatum is one of the most problematic invasive macrophytes in the United States. Dichlorophenoxyacetic acid (2, 4-D) herbicides are widely used to control EWM and have been used since the 1950’s. However, little is known regarding the effects of 2, 4-D on larval fishes outside of laboratory experiments. The objectives of this study were to determine if 2, 4-D treatments affect: 1) feeding, survival, and growth of larval fish, and 2) diversity, abundance, and size of zooplankton. During 2015-2017, research was conducted on six lakes in northern Wisconsin, including a pre-treatment (2015), treatment (2016) and post-treatment year (2017). During 2016 (treatment year), three lakes served as reference systems, while three other lakes received a whole-lake 2, 4-D herbicide treatment. Zooplankton taxa followed similar trends between 2015 and 2016, but these trends were inconsistent in treatment lakes for some taxa in 2017. Larval Yellow Perch peak abundance was lower in treatment lakes during 2017 compared to 2016, but was similar between these years in reference systems. No difference in survival was observed between reference and treatment lake net pen trials for both juvenile Yellow Perch (F=1.62, df =1, 3, P =0.2926) and Bluegill (F=0.00, df =1, 7, P =0.9539). Information collected during this study will aid managers in determining the use of 2, 4-D treatments for whole lake manipulations.

Tuesday January 30, 2018 1:40pm - 2:00pm CST