Effects of Reservoir Characteristics on Crappie Populations in Small Southern Impoundments

Abstract

Crappie (Pomoxis spp.) fisheries are important across much of North America, but most research has focused on management in larger reservoirs. Understanding factors that affect crappie populations in small reservoirs could improve management approaches because manipulation of physicochemical, biological, and morphometric factors may be feasible in these smaller systems. We examined biotic and abiotic features that influence crappie (black crappie P. nigromaculatus and white crappie P. annularis) species dominance, growth, condition, and trap net catch­per­effort (CPE) in 16 small southern U.S. reservoirs (28–357 ha). Morphometric and physical habitat characteristics, water quality variables, and fish community characteristics were compared to crappie population metrics using an ordination approach. Reservoirs varied considerably in morphometrics, physi­cochemical environment, and fish communities, as well as in crappie population dynamics. Reservoir maximum and relative depth and productivity as measured by chlorophyll­a was associated with crappie species composition, as white crappie were more common in shallow and more productive systems and black crappie were associated with deeper systems with greater water transparency. Growth was faster in deeper reservoirs and CPE of both species increased with reservoir surface area. Largemouth bass Micropterus nigricans and crappie population characteristics demonstrated a strong rela­tionship, with largemouth bass electrofishing catch­per­effort (c/f) inversely associated with crappie CPE, and directly associated to crappie growth rate and condition. These results suggest that managers should consider reservoir depth and productivity when selecting crappie species for introduction into new or renovated reservoirs, and that predator populations can be manipulated to improve growth and condition of crappie when crappie are of primary management importance.