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Georgia Journal of Science

Article Title

VALIDATION OF ESTIMATED SICKLEFIN REDHORSE GROWTH FROM PECTORAL FIN RAYS USING RECAPTURED INDIVIDUALS

Abstract

The sicklefin redhorse (SFR) Moxostoma sp. is endemic to the upper Tennessee River watershed in western North Carolina and north Georgia. It is considered state-endangered in north Georgia with a single population existing in Brasstown Creek, a tributary to the Hiwassee River watershed. Previous study of this population determined age structure and growth rates using sectioned pectoral fin rays. However, age validation was not conducted, and the accuracy of estimated growth rates was not assessed. SFR were captured in April from 2014 to 2017 using seines and a modified fyke net. Captured individuals were tagged with passive integrated transponder (PIT) tags, measured to total length (mm) and released. Sixteen SFR were recaptured in either April 2016 or April 2017, with one individual being recaptured twice. A von Bertalanffy growth model (VBG) was developed from pectoral fin rays and compared to a length-increment version of the VBG from marked-recapture data. Comparisons of growth rates from pectoral fin ray and mark-recapture methods were evaluated based upon the VBG-predicted age for recaptured lengths and the apparent age from the length-increment model for recaptured lengths. Little difference in growth was demonstrated between estimated growth from fin rays and observed growth from recaptured SFR. The estimated growth from recaptured fish was slightly lower with the widest differences at younger ages (12 – 15 years). Similarity between observed growth and predicted suggests that the use of pectoral fin rays, a method that is not lethal, provides an accurate assessment of SFR growth. Accurate estimation of ages and growth will allow for estimation of other population characteristics and for additional population modeling with this species. Further sampling will occur to increase the number of recaptured SFR to strengthen this analysis.

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