Distributional changes of the fishes of the Hatchie River in west Tennessee and north Mississippi

The Hatchie River in northern Mississippi and western Tennessee is the only coastal plain river in TN that escaped the extensive channelization efforts of the Army Corps of Engineers in the region. As such, it is one of the last refuges for many of the endemic coastal plain fishes that have experienced wide spread extirpation. The Hatchie was thoroughly surveyed by W.C. Starnes in 1973. He concluded that barring extensive channelization of the system or increased deleterious agricultural practices the ichthyofauna of the Hatchie should remain intact. At that point 90 species had been recorded from the system and 109 species were expected to occur. Eleven of those species were ictalurids, which gives the system the distinction of having the most diverse catfish fauna in North America. The current survey was conducted to determine if the distributions of fishes in the Hatchie have changed since the mid- l 970s. The use of the relatively new method of boat shocking drastically improved knowledge of big river fish distributions in the system. Collections during the field seasons of 2001-2003 resulted in records of 88 species, in 19 families. This brings the total known species for the system to a total of 108 and 125 are expected to occur. Six new species (Polyodon spathula, Ctenopharyngodon idella, Pimephales promelas, Erimyzon sucetta, Jctiobus niger, Ameiurus nebulosus) were recorded in the system. Cyprinella lutrensis appears to be the only known species that is expanding its range while Lythrurus umbratilis and Etheostoma parvipinne have apparently been nearly extirpated from those same regions that C. lutrensis is populating. The apparent range reductions of Phenacobius mirabilis and Amia calva are most likely artifacts of collection methods. Currently, the main threat to the stability of the Hatchie River ichthyofauna appears to be deleterious agricultural and sylvicultural practices, which are the most likely cause of heavy silt loads and rapid rates of channel incision and resultant sand deposition.