Fishes in the lower San Pedro Mezquital River, Nayarit, Mexico

Resumen en inglés: "The San Pedro Mezquital River is the seventh largest river in Mexico, and flows through the Sierra Madre Occidental into the Marismas Nacionales Biosphere Reserve, on the coast of the state of Nayarit. The present study is to conform a systematic checklist of fishes in the lower basin of the San Pedro Mezquital River. In total, 52 species were collected from 24 families. Four native species were collected (Atherinella crystallina, Poecilia butleri, Poeciliopsis latidens and Poeciliopsis prolifica) that are federally protected. Five of the collected species were new records for the state of Nayarit. This checklist constitutes a first approximation of the fish fauna present in the San Pedro Mezquital River. However, the construction of the Las Cruces dam upstream, will modify the basin hydrology, worsen the introduction of exotic species and create habitat loss, which can have immediate negative impacts on the fish communities in this region. "