Bridle Shiner: detection, distribution, and conservation genetics of a rare, imperiled minnow

Researchers on this project include Dr. Jason C. Vokoun, Center Affiliated Associate Professor of Fisheries, Kasey Pregler, MS 2014, Jan Michael-Hessenauer, PhD 2015, Timothy Jensen, MS 2012, and Neal Hagstrom, CT DEEP Inland Fisheies Division.

Bridle Shiner (Notropis bifrenatus) carry special distinctions ranging from state endangered, threatened, and regionally rare throughout their native range. The small fish was relatively common in Connecticut in early surveys up into the 1960s. The species lives in shallow ponds, low-gradient streams and swamps, and is always associated with abundant vegetation– which it uses for reproduction.

By the 1980s-90s, Bridle Shiner were only detected at 8 locations, down from 56 known historic locations. Dr. Vokoun and a group of graduate students have been collaborating with Neal Hagstrom at the Inland Fisheries Division to attempt to better understand the conservation status of this imperiled minnow. In 2011, Timothy Jensen began working in the Shunock River in North Stonington, CT, and documented habitat usage and detection probabilities in places where the species was known to be present.

When sampling rare organisms, not collecting a species when it is in fact present is always an undesirable possibility. We call this problem ‘imperfect detection’. By the end of 2012, Kasey Pregler had evidence to suggest that a switch from seining to electrofishing methods among surveys in the 1960s and the 1980s probably had an effect on detection. This meant that Bridle shiner might well exist in places where they were assumed to be absent. She is now resurveying known historic locations with a seine and has ‘rediscovered’ a few populations.

Publications resulting from this research:

Pregler, K. C., J. C. Vokoun, T. Jensen and N Hagstrom. 2015. Using multimethod occupancy estimation models to quantify gear differences in detection probabilities: is backpack electrofishing missing occurrences for a species of concern? Transactions of the American Fisheries Society 144:89-95.

Jensen, T. and J. C. Vokoun. 2013. Using multistate occupancy estimation to model habitat use in difficult-to-sample watersheds: bridle shiner in a low-gradient swampy stream. Canadian Journal of Fisheries and Aquatic Sciences 70:1429-1437.

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