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EVALUATION OF AGE AND GROWTH OF REDHORSES IN BRASSTOWN CREEK, GEORGIA

Abstract

Redhorses (Genus: Moxostoma) are migratory, benthic fishes inhabiting the lotic waters of the United States. High endemism of redhorses exists in the southeastern U.S., and many species are of conservation concern due to their susceptibility to water quality and habitat degradation. Brasstown Creek in north Georgia contains 5 sympatric species of redhorses, including the silver (M. anisurum), golden (M. erythurum), black (M. dusquenii), river (M. carinatum) and sicklefin (Moxostoma sp.) redhorses. This study estimated age and growth rates of redhorses from a non-lethal technique utilizing pectoral fin rays. Von Bertalannfy growth (VBG) models were developed for each species using nonlinear model fitting methods and compared to each other by fitting eight models of which each model represented a difference between species for at least one VBG parameter. Models were compared sequentially using the likelihood ratio and extra sum-of-squares tests. Sicklefin redhorse, a state-endangered species, exhibited the slowest rate of growth and was the longest-lived species whereas silver redhorses grew the fastest but were shorter-lived. In comparison to other redhorse age and growth studies conducted across a latitudinal gradient from Canada to Georgia, Brasstown Creek redhorses are among the faster growing populations, presumably due to warmer temperatures and a longer growing season.

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