Conservation of Bridle Shiner (Notropis bifrenatus) in Connecticut: Issues in Detecting an Elusive Species

Bridle Shiner (Notropis bifrenatus) is apparently declining over most of its range and is currently listed as a species of concern in Connecticut. Using an occupancy modeling framework in program PRESENCE, my study compared seining and electrofishing backpack unit detection probabilities of Bridle Shiner. This research indicated the apparent decline of Bridle Shiner in the state was in part due to changes in sampling gear used for statewide surveys. Seining used 50 years ago was demonstrably more effective at capturing Bridle Shiner than the currently favored and more frequently used electrofishing gear. In light of this recent finding, I seined at known historic sites in Connecticut and found that some populations once thought to be extirpated are in fact extant. Nonetheless, Bridle Shiner has a sharply reduced range in Connecticut, in that the number of site occurrences has declined 60% over 50 years. Using geospatial tools I identified landscape-scale habitat measures that were potential correlates of extirpation. Using logistic regression, I investigated metrics associated with land cover change, such as impervious surfaces and those indicative of habitat fragmentation and patch isolation. I found that the current Bridle Shiner distribution in Connecticut can be explained by areas of high forest cover and low impervious cover. My results provide needed context on declines in this species and potential avenues for conservation actions