Abstract
Fish stocking (artificial supplementation) has been used to augment populations and angling opportunities. However, genetic composition and adaptations of native fish populations may be affected, raising management concerns. From 1995 to 2000, the New York State Department of Environmental Conservation stocked Walleye Sander vitreus fry and fingerlings from the Maumee River (western Lake Erie) into Cattaraugus Creek (eastern Lake Erie). We analyzed nuclear microsatellite (sat) DNA and mitochondrial DNA (mtDNA) variation in Cattaraugus Creek Walleyes for comparisons between prestocking and poststocking groups, among annual spawning runs (1998–2011), among age cohorts, and between sexes. Results for genetic differentiation (index FST) were not significant between prestocking and poststocking groups (sat: FST = 0.003; mtDNA: FST < 0.001), and the two groups did not resemble stocked Maumee River fingerlings (sat: FST = 0.003–0.012; mtDNA: FST = 0.076–0.090). Tests for differentiation were not significant among annual spawning runs (sat: FST = <0.001–0.007; mtDNA: FST = <0.001–0.049), among age cohorts (sat: FST = <0.001–0.006; mtDNA: FST = <0.001–0.097), or between sexes (sat: FST < 0.001; mtDNA: FST < 0.001). Genetic diversity levels were high and consistent (sat: observed heterozygosity [mean ± SE] = 0.71 ± 0.04; mtDNA: haplotype diversity = 0.79 ± 0.01). Thus, despite stocking, the genetic signature of the native spawning run remained distinctive. However, the genetic composition of the local wild population and the stocking source should be assessed prior to any future supplementation plans.
Received December 6, 2013; accepted June 12, 2014
ACKNOWLEDGMENTS
This is Contribution 2014-15 from the Lake Erie Center, University of Toledo. The research was funded by grants to C.A.S. (lead scientist and principal investigator), including grants from the National Oceanic and Atmospheric Administration Ohio Sea Grant Program (R/LR-9PD), U.S. Environmental Protection Agency (DGE-0742395), the National Science Foundation (NSF) Undergraduate Research and Mentoring Program (0829252, which provided support for H.A.D.), and the NSF Graduate Teaching Fellows in K–12 Education Program (0742395, which provided support for A.E.H.). We thank B. Beckwith, D. Einhouse, D. Sek, D. Zellar, and R. Zimar (NYSDEC collectors) for contributing samples. We also thank members of the GLGL, including M. Neilson, L. Pierce, C. Prichard, and S. Yerga-Woolwine, for laboratory assistance and manuscript comments. P. Uzmann, M. Gray, R. Lohner, and P. Struffolino (Lake Erie Center) provided logistic support.