Population Characteristics of Flathead Catfish in Channelized and Unchannelized Reaches of the Middle Missouri River from 1997 to 2008
Tim K. Porter, Gerald E. Mestl, and Mark T. Porath
Abstract.—An assessment of the flathead catfish Pylodictis olivaris population in the Missouri River bordering Nebraska was conducted between 1997 through 2008. The Missouri River was divided into four sections based on physical and geomorphologic uniqueness (upper unchannelized, lower unchannelized, upper channelized, and lower channelized). Two sections were sampled annually, and each section was sampled on alternate years. Boat electrofishing collected 12,846 fish in 83.5 h from 701 sampling stations. Most flathead catfish sampled (98%) were less than 510 mm total length (quality length), with significantly more fish captured in channelized than unchannelized reach. Fish from channelized sections also had higher mean total lengths and larger growth increments but were in poorer body condition than those from unchannelized sections. Low relative abundance of flathead catfish in the upper unchannelized section and scarcity of large individuals were attributed to poor habitat conditions. Habitat restoration along with restoring natural riverine processes would return the river to a more natural state and would not only benefit flathead catfish, but other native Missouri River fishes as well.