The efficacy of small-scale removal of an invasive species (redbreast sunfish, Lepomis auritus) by electrofishing

Abstract

Redbreast sunfish (Lepomis auritus) in Richland Creek, Haywood County, NC, were studied todetermine if back-pack electrofishing was an effective method of removal of this invasive species. Threestudy sites were established, with 100 m removal reaches and paired 100 m control reaches which wereresampled at intervals over a nine month period to test for population depletion by electrofishing. Allredbreast sunfish were sacrificed from removal reaches while those captured in control reaches werereturned to the stream after marking by fin clipping. While electrofishing, any rock bass (Ambloplitesrupestris) captured were measured noted to look for re-establishment in areas where redbreast sunfish hadbeen removed.The results indicate that the population was significantly smaller in removal reaches; averagedover the period of the study, population estimates from removal reaches were approximately 50% lowerthan those from control reaches. However, there was not a significant difference of the interaction ofmonth by treatment. While the local populations of redbreast sunfish in removal reaches in RichlandCreek may have been reduced by electrofishing, fin-clipped fish from control reaches were occasionallycaptured in removal reaches suggesting upstream-downstream movement. Given that the small reservoirdownstream (Lake Junaluska) may serve as a source population, I suspect that a continuing program of removal would be needed in order to control the population by electrofishing. I was unable to detect aresponse of rock bass to the removal of redbreast sunfish due to their extremely low capture rate

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