Prescribed Fire as a Tool to for Sensitive Species Conservation

Authors: Cassie Mellon, Kevin Wheeler

Year: 2018

Abstract

Least Chub, Iotichthys phlegethontis, is endemic to the Bonneville Basin of Utah with only six isolated extant populations. One of these populations occurs at Gandy Marsh which is a complex of approximately 50 springheads located in the Snake Valley of Utah. Gandy Marsh provides habitat for least chub as well as Utah Chub, Gila atraria, Speckled Dace, Rhinichthys osculus, Columbia Spotted Frog, Rana lueteventris, and Northern Leopard Frog, Rana pipiens. Portions of this spring complex have been protected as a Bureau of Land Management Area of Critical Environmental Concern since 1992. Two livestock grazing exclosures (12 and 50 acres), which encompass 25 springheads, were built in the early 1990’s to protect the unique ecosystem and habitat of Gandy Marsh. The discharge of these springheads varies seasonally. Open water is primarily restricted to springheads in the summer. In the spring and fall water flows through springbrooks to seasonally flooded basins. Occupancy surveys for Least Chub at the springheads have been conducted every 1 to 3 years in August since the early 1990’s. Declines in least chub occupancy at springheads within the exclosures were documented beginning in 2010, while occupancy at springheads outside the exclosures remained unchanged. This decline was attributed to a buildup of decadent vegetation within the exclosures which clogged the channels, limited open water, and prevented least chub from leaving or returning to the springheads during high water periods. We believed that Least Chub needed to leave the springheads to reach the seasonally flooded basins to spawn and then return to the springheads to overwinter and oversummer. With the buildup of vegetation, the channels were too clogged for Least Chub to complete this portion of their life cycle which led to a loss of Least Chub inside springheads in the exclosures. A prescribed burn was conducted inside both exclosures in October 2017 with the goal of removing vegetation and increasing open water habitat to allow Least Chub to return to the springheads in the exclosures. In monitoring from 2010 to 2016, Least Chub were only found in one exclosure in one year. During monitoring in August 2018, Least Chub were documented in five springheads inside the exclosures. This increase in occupancy indicates that prescribed fire can be an effective tool to remove vegetation, maintain open water, and allow Least Chub to naturally recolonize springheads. We will continue to monitor Least Chub occupancy and vegetation response to determine frequency of future burns or other management efforts needed to help maintain this population.