Demographics of Populations of Mooneye in St. Lawrence Tributaries of Raquette and St. Regis Rivers, Ny

A gillnet survey in 2024–2025 in the lower Raquette and St. Regis rivers caught 63 Hiodon tergisus (Mooneye) and provided insights into their life history and relative abundance. Mooneye were caught at the river mouths and appear to be part of the population in Lake St. Francis on the US border with Ontario and Quebec, Canada. The 3 sample dates in 2024–2025 showed presence of both juveniles and adults and provided evidence in support of a breeding population. Mooneye spawning likely occurred in the Raquette River, as indicated by young of year and females in pre-spawn and post-spawn condition. The sizes and relative abundances were compared to those in the Oswegatchie River, which possesses the only other undisputedly sustained population of Mooneye in northern New York. Mooneye is a threatened species according to New York regulations and are rarely encountered, adding to the significance of these findings.