Modeling the Potential Effects of Intermittent Perturbations on Endangered Stonecats

In Vermont, stonecats (Noturus flavus) are state endangered as their known distribution is limited to two rivers. In 2012 and 2013, we captured and PIT tagged (> 90 mm total length) and VIE marked all stonecats collected in the LaPlatte and Missisquoi rivers. A total of 1229 were PIT tagged in the LaPlatte and 92 in the Missisquoi. Based on the capture numbers and large size range of individuals, we assume the population in the LaPlatte River, which provides quality benthic habitat, is relatively stable. However, the Missisquoi River population has the potential for increased mortalities from two sources of intermittent perturbations; i.e., lampricide TFM (3-trifluoromethyl-4-nitrophenol) treatment every four years and dewatering during drought conditions. During the 2012 TFM treatment, there was minimal known mortality of stonecats (N=2). Unfortunately, an unplanned dewatering event occurred in 2012 below a dam in the stonecat habitat, which resulted in six known dead stonecats. Using stonecat population data from the LaPlatte River, we modeled the potential effects of these intermittent mortalities to provide a better understanding of the long-term status of stonecats in the Missisquoi River below the dam.