Puchala, E.A., D.L. Parrish, and T.M. Donovan. 2016. Predicting the stability of endangered Stonecats (Noturus flavus) in the LaPlatte River, Vermont. Transactions of the American Fisheries Society 145: 903-912.
Abstract
Stonecats (Noturus flavus, Rafinesque 1818) in Vermont fit into a rare distribution pattern, as designated by Rabinowitz, because their known distribution is limited to two systems, the LaPlatte and Missisquoi rivers. Here we focus on Stonecats in the LaPlatte River to predict the stability of the population. In 2012, 2013, and 2014 we captured, PIT tagged (> 90 mm total length), and VIE marked all Stonecats collected using backpack electrofishing. A total of 1671 Stonecats was captured, and of those, 1252 were PIT tagged. Only 12% (N=156) of the PIT tagged fish were recaptured and only 22 were recaptured more than one time. We used the Pradel model in Program MARK to estimate the survival and seniority of Stonecats and these values were used to derive lambda (λ), the population rate of change. We ran a total of 64 models in our candidate set with the following covariates: total length, maximum temperature, season, maximum discharge, and area sampled. Model results estimated that survival was highest in the spring, and increased with increasing total length of individuals. We also estimated increases in capture probability with increasing area sampled. We derived an annual λ of 0.9826, which indicates a slightly decreasing population. With only three years of data and a low recapture rate, our estimate has some uncertainty. Although the population could be declining at a slow rate, we have provided insight into population parameters that were otherwise unknown.