Do conservation management actions improve native fish communities?

Authors: Skyler Hedden, Brandon Albrecht, Ron Rogers, Kevin Guadalupe, Rick Fridell, Melinda Bennion, Martin Schijf, Kody Callister

Year: 2023

Abstract

Resource managers and agencies are tasked with conducting management actions to improve native communities or offset negative anthropogenic activities. But measuring the effectiveness of conservation actions is difficult due to temporal variations in fish communities, time lags, and lack of control sites to examine differences or changes in fish community structure and density. Thus, the effectiveness of conservation management actions often goes unmeasured and at times managers can be uncertain of their efforts. In the Virgin River, which flows across portions of Utah, Arizona, and Nevada, native fish management actions have differed substantially between the upper and lower portions of the river. In the upper Virgin River nonnative fish barriers have been constructed, rotenone applications have eradicated nonnative fish, native fish stocking plans have been employed, and pump back systems have been installed to keep stream temperatures within the desirable ranges of native fish. While in the lower Virgin River, efforts have largely been focused on collecting data towards long term datasets with relatively minimal management actions being performed. In this talk, native fish community structure and densities are compared between the upper and lower Virgin River to examine if any differences are observed between the two areas that have had substantial differences in conservation management actions. Fish community structure differed considerably between the two reaches, largely driven by the eradication of nonnative fish from the upper Virgin River. When only examining native fish community structure, differences were less apparent, with only two species driving differences. Our results suggest that conservation management actions do have positive impacts on native fish communities, but these actions may be more influential for certain species.