Fishery and Population Characteristics of Blue Catfish and Channel Catfish and Potential Impacts of Minimum Length Limits on the Fishery in Lake Wilson, Alabama

Abstract

AbstractA popular recreational and commercial fishery for blue catfish Ictalurus furcatus and channel catfish I. punctatus exists at Lake Wilson, Alabama (Tennessee River). We examined the fishery, exploitation, angler size selectivity, and population demographics of these two species at Lake Wilson. In addition, we explored management strategies to enhance the fishery of trophy blue catfish. Currently, Alabama has no bag or minimum‐length‐limit regulations for catfish, except for the harvest of fish over 864 mm total length (TL). From April to October 2006, catfish harvest was high (8 kg/ha), and angler catch and harvest rates averaged 1.5 and 1.2 fish/h, respectively. The majority of fish harvested were between 300 and 600 mm TL, and anglers harvested larger fish in proportion to the sample population. Catfish were collected by low‐frequency (15‐MHz) DC electrofishing; they were aged with otoliths from 180 and 122 blue catfish and channel catfish, respectively, subsamples of 2,905 blue catfish and 699 channel catfish. Fish over 300 mm TL were tagged with Carlin dangler tags to estimate exploitation. Accounting for tag loss and variations in angler nonreporting rates (20–70%), we estimated that annual exploitation ranged from 8% to 22% for blue catfish and from 4% to 11% for channel catfish. Of the tagged fish harvested, 33% came from seven commercial fishers. Blue catfish and channel catfish displayed different life histories, which pointed to contrasting management strategies for increasing yield. Blue catfish were longer‐lived (maximum age = 25 years), expressed slower growth (von Bertalanffy K = 0.081), and had lower natural mortality (M = 0.16) than channel catfish (maximum age = 12 years; von Bertalanffy K = 0.148; M = 0.29). Increasing minimum length limits from 300 to 660 mm for blue catfish would increase yield up to 50%, prevent growth overfishing, and increase the abundance of memorable‐length (890‐mm) blue catfish over our range of estimated exploitation. However, for channel catfish, minimum length limits greater than 300 mm would result in a lower yield. High length limits could drastically reduce the angler harvest of catfish but increase the abundance of memorable‐length and larger blue catfish. Even so, the anglers surveyed preferred to harvest smaller fish. Fishing mortality was probably equal to natural mortality for blue catfish, but for channel catfish fishing mortality was less than natural mortality. On the basis of these observations, angler catches, the lack of angler species recognition, and the abundance of small catfish, we currently do not recommend bag or minimum length limits for this fishery.