A comparison of mechanical removal efforts of Green sunfish, Lepomis cyanellus, from three native fish streams in Arizona

Authors: Tiffany Love-Chezem, Clayton D. Crowder, Anthony T. Robinson, David Partridge

Year: 2014 (xlvi)

Abstract

Presence of non-native fishes is often correlated with decline of native fishes, and investments of time and money to chemically or mechanically remove these fish can be significant. One example is the highly piscivorous Green sunfish, Lepomis cyanellus, which is linked to local extirpations of native fishes. Three native fish streams in Arizona, with ongoing L. cyanellus mechanical removal projects, were compared to assess effects of removal frequency and methodology. East Ash Creek has a long-term, frequent removal effort (monthly removals since November 2013) and large population of L. cyanellus, Spring Creek has a short-term, frequent removal effort (eight removal trips since May 2014) and a small population, and Redfield Canyon has a long-term, infrequent removal effort (two to three times a year since 2007) and an intermediate population. The most effective method at East Ash Creek was backpack electrofishing, trapping was more effective in Spring Creek, and Redfield Canyon showed similar result for trapping and backpack electrofishing. East Ash Creek is the only system exhibiting a decline in catch per unit effort (CPUE) over time, with no L. cyanellus captured in August 2014. The differential success of the methods is likely due to the size of the populations and habitat differences; with trapping more effective on smaller populations and in larger more complex habitat. The seemingly stable CPUE in Redfield Canyon and Spring Creek is likely due lower removal effort and connectivity with source populations. Overall this comparison has provided insights in controlling and eliminating L. cyanellus.

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