Utility of Tournament Data for Assessing Effects of Eliminating Commercial Catfish Harvest in the Missouri River

We examined tournament records for 1989 through 1998 from the 4F Flathead Club in St. Joseph, Missouri, to determine whether tournament data from catfish (i.e., channel catfish Ictalurus punctatus, blue catfish I. furcatus, and flathead catfish Pylodictis olivaris) anglers could be used to detect changes in adult catfish populations (primarily flathead catfish) after commercial harvest of catfish from the Missouri River was prohibited in July 1992. Data from 1989 through 1992 were considered preregulation, and 1993–1998 data were considered postregulation. We found that the fish weight needed to place first, second, or third in a tournament increased significantly (P < 0.01) after the regulation. The mean weight of the big fish for each tournament increased after the commercial ban, and the total weight of fish for each two-person team was 3 lb greater after the regulation. These changes coincided with findings of angler surveys on the Missouri River near St. Joseph, which had indicated that catch rates of harvested catfish near St. Joseph were higher after the regulation, especially for flathead catfish. We conclude that tournament catch statistics were sensitive enough to detect changes in the size structure of adult catfish populations in the Missouri River near St. Joseph after the prohibition of commercial catfish harvest.