Reproductive Effort and Lipid Dynamics of the Emerald Shiner (Notropis atherinoides) in the Upper Niagara River, New York

Life history theory predicts that reproductive characteristics of organisms will be shaped by biotic and abiotic factors to maximize their overall fitness. In this study, I investigated how growth, reproductive effort, and lipid dynamics vary ontogenetically and seasonally for emerald shiners (Notropis atherinoides) in the upper Niagara River. Growth rates were highest in age 2 shiners and lower in age 1 and age 3 individuals. Evidence of reproduction was found beginning at age 1, and reproductive investment as measured by ovarian lipid content was lowest in age 1 and age 2 individuals and greatest in age 3 fish. All age classes exhibited significant changes in somatic lipids across sampling seasons, with minima in spring and maxima in fall. Fulton’s condition factor K did not accurately represent variation in somatic lipid reserves that were found in this study, and therefore this index is not likely to be an accurate measure of overall health and robustness for this species. My findings suggest that emerald shiners exhibit a life history strategy where somatic growth is prioritized over reproduction until their third year of life when large investments into reproduction result in significantly reduced growth rates. Although prior studies have examined growth and reproductive traits of the emerald shiner, my study is the first to document significant changes in lipid dynamics across seasons and age groups in this native keystone species