Variation in Population Characteristics and Gear Selection between Black and White Crappies in Tennessee Reservoirs: Potential Effects on Management Decisions

Abstract

The population characteristics of crappies Pomoxis spp. were examined in three Tennessee reservoirs (Kentucky, Barkley, and Woods) sampled in fall with trap nets and electrofishing. Kentucky and Barkley reservoirs are large main-stem impoundments on the Tennessee and Cumberland rivers, respectively. Woods Reservoir is a small tributary storage impoundment on the Elk River in south-central Tennessee. Mean length at age was similar between white crappies P. annularis and black crappies P. nigromaculatus at ages 1 and 2 in Barkley Reservoir and at age 1 in Kentucky Reservoir. Thereafter, white crappies were consistently larger than black crappies at older ages, and the differences in mean length commonly exceeded 30 mm once the fish in both reservoirs were age 4. Crappie species compositions in concomitant electrofishing and trap-net samples were relatively similar in the two main-stem reservoirs. However, black crappies represented much higher proportions in the trap-net samples than they did in the electrofishing samples in Woods Reservoir. Electrofishing consistently collected larger fish than trap nets in all three reservoirs. Managers should be aware that variability in species composition and size structure due to sampling area and gear type can affect the estimates of crappie population characteristics, which can, in turn, affect modeling results and ultimately management decisions. We feel that the best sampling regime for collecting crappies in Tennessee reservoirs would be to use fall trap-net sampling to index year-class strength and concurrent electrofishing sampling to collect the larger individuals necessary for age and growth analysis.