The success of Green Sunfish removals in McGee Wash

Authors: Brett Montgomery, William Partridge, Matthew Chmiel

Year: 2019

Abstract

The threat that invasive fish species pose to native aquatic species is substantial. In McGee Wash, a tributary to Trout Creek in the Bill Williams River drainage, Green Sunfish, Lepomis cyanellus, pose a threat to the native aquatic species present. In 2017, the Arizona Game and Fish Department began a project to remove non-native Green Sunfish from McGee Wash to eliminate the threat to native aquatic species. McGee Wash has a 1.5 km stretch of perennial water that hosts an assemblage of native aquatic species including Roundtail Chub, Gila robusta, Desert Sucker, Catostomus clarkii, Sonora Sucker, Catostomus insignis, Lowland Leopard Frogs, Lithobates yavapaiensis, and Sonora Mud Turtles, Kinosternon sonoriense. Removal efforts have consisted of monthly single pass backpack electrofishing and minnow traps to collect and remove all Green Sunfish. Initially Green Sunfish inhabited the entire perennial reach, and various age classes were found throughout the reach. After 33 mechanical removal trips the fish assemblage in McGee Wash has changed from a non-native dominated fish assemblage to a native fish dominated assemblage and few Green Sunfish have been detected. Mechanical removals will continue until Green Sunfish are eradicated from the reach. However, suppression of Green Sunfish has allowed the native aquatic species to repopulate the stream and distribute throughout the perennial reach.