Effects of a 356-mm Minimum Length Limit on the Population Characteristics and Sport Fishery of Smallmouth Bass in the Shoals Reach of the Tennessee River, Alabama

Abstract

The Shoals Reach, a 20-km section of the Tennessee River below Wilson Dam, Alabama, has a national reputation as an excellent fishery for smallmouth bass Micropterus dolomieu. To protect and enhance this smallmouth bass fishery, a 356-mm minimum total length (TL) limit was established in this region in 1991. We sampled smallmouth bass in the fall of 1995 and spring of 1996 to determine if the regulation had any effects on the population characteristics of this fishery. A creel survey was conducted during 1996 to estimate angler effort, catch, and harvest of smallmouth bass, and to evaluate angler values, opinions, and practices. Electrofishing catch rates for juvenile (<280-mm TL) and adult (≥280-mm TL) smallmouth bass significantly (P < 0.05) increased compared with preregulation data (1988). Growth rates in 1995–1996 were higher for fish younger than age 3 than in 1988; however, otoliths were used to age fish in 1995–1996, whereas scales were used in 1988. Length indices showed a high proportion of preferred-length (≥350-mm) fish in the population, and relative weights were similar before and after the length limit. The annual mortality rate was also similar before and after the regulation. Year-class abundance fluctuated greatly and was negatively related to discharge through Wilson Dam from April–July, which corresponds to the spawning and postspawn periods. The angler catch rate for smallmouth bass nearly doubled compared with preregulation data, whereas the harvest rate decreased by nearly an order of magnitude. Smallmouth bass anglers released 98% of their catch, the same percentage of smallmouth bass anglers who reported practicing catch and release. The 356-mm minimum length limit appeared to improve the quality of this fishery. However, the catch-and-release philosophy practiced by most smallmouth bass anglers in the Shoals Reach cannot be overlooked as an important factor that has had, and will continue to have, positive influences on this fishery.