Assessing Angler Exploitation of Blue Catfish and Flathead Catfish in a Missouri Reservoir Using Reward Tags
Kevin P. Sullivan and Ivan W. Vining
Abstract.—The Missouri Department of Conservation suspected that blue catfish Ictalurus furcatus and flathead catfish Pylodictis olivaris were being heavily exploited by anglers in 22,539-ha Harry S. Truman Reservoir in west-central Missouri. A reward tag study was initiated in 2004 to determine angler exploitation rates for both species. Three hundred blue catfish ≥ 482 mm total length (TL) and 194 flathead catfish ≥ 508 mm TL were equipped with transbody Carlin dangler reward tags in 2004 and 2005, respectively. All reward tags displayed a reward value of US$50. A 5-year post-tagging estimate of annual exploitation (u) was calculated with a 25% annual correction for angler nonreporting and a one-time correction for tag loss. The estimated annual exploitation rates for blue catfish ranged from 25.5% to 33.4% with a mean of 28.8%. The estimated cumulative exploitation rate (U) at 5-years post-tagging was 81.7% for all sizes of tagged blue catfish and 92.4% for tagged blue catfish ≥ 610 mm TL. The estimated annual exploitation rates for flathead catfish ranged from 0% to 3.9% with a mean of 1.8%. The estimated cumulative exploitation rate at 5-years post-tagging for flathead catfish was 8.8%. These exploitation rates indicate that blue catfish are being heavily exploited while flathead catfish are not. Of all the reward tagged blue catfish that were reported by anglers, 7% were reported as released while 22% of the reported flathead catfish were released. These results are being used to examine possible regulation changes to protect the blue catfish fishery at Truman Reservoir.