Mechanical removal of green sunfish, Lepomis cyanellus, from Bonita Creek, AZ

Authors: Brian R. Kesner, Heidi B. Blasius, Paul C. Marsh

Year: 2013 (xlv)

Abstract

Bonita Creek is a small tributary that flows into the Gila River about 10 miles east of Safford, AZ. A fish barrier was constructed in 2008, approximately 1.2 miles upstream from the confluence and the creek was chemically renovated with the piscicide rotenone to remove nonnative fishes upstream of the barrier. Shortly after renovation, nonnative fishes were discovered in the renovated portion of Bonita Creek. Western mosquitofish, Gambusia affinis, and green sunfish, Lepomis cyanellus, in 2009, fathead minnow, Pimephales promelas, in 2010, and yellow bullhead, Ameiurus natalis, in 2011. The nonnatives, especially green sunfish and yellow bullhead, threaten populations of native Gila chub, Gila intermedia, longfin dace, Agosia chrysogaster, speckled dace, Rhinichthys osculus, Sonora sucker Catostomus insignis, and Gila topminnow Poeciliopsis occidentalis. Efforts to reduce or remove green sunfish were initiated in 2009 and have continued through 2013. Minnow traps of various types as well as hoop nets, electrofishing, seining, and dip netting have all been used in an attempt to reduce or eradicate the species from the system. Although this effort has reduced the abundance of green sunfish, yellow bullhead catch has increased over time. Additional effort will be required to reduce yellow bullhead abundance if the species is determined to be a threat to native fish species in Bonita Creek.