Population structure of white crappie in flood prevention lakes, of north-central Texas

Abstract

During 1976-1980, fish population and limnological data were collected from 12 flood prevention lakes in north-central Texas. Limnological conditions varied among lakes primarily due to differing soil types. Fish samples, collected by gillnetting, hoopnetting, seining, and electrofishing, were dominated by white crappie (Pomoxis annularis) in nine lakes, and by bluegill (Lepomis macrochirus) and black bullhead (Ictalurus melas) in three lakes. Crappie abundance varied greatly among lakes, but was relatively stable over time in most lakes. Four lakes had large variations in population abundance due to dominant year-classes. Both number and biomass were significantly greater in the newer and shallower lakes. Proportional Stock Densities (PSD) varied from 0 to 100%, with the majority less than 30%. Size structure was similar between years. PSDs varied inversely with population abundance except at lakes which consistently had the highest PSDs. Relative Stock Densities (RSD) for crappie > 250 mm TL in May ranged from 0 to 81%, with the majority less than 10%. Crappie in these lakes were quite young. Maximum age attained was age VI, but most samples were comprised of fish of age IV or younger. Age II and age III crappie were dominant in the samples. PSDs for crappie in May were negatively related to the relative abundance of age II fish. Age I fish typically were of substock size (< 130 mm TL) in May, while age III and older crappie had generally reached quality size (> 200 mm TL). Mean relative weight (Wr) ranged from 68-96 for sub-quality stock-size crappie, and from 69-112 for quality-size crappie. Lack of correlation between Wr means for sub-quality stock-size and quality-size crappie indicated that forage conditions differed within lakes for these size groups. Within-lake variation of Wr among years indicated that forage of the appropriate size was likely variable and limiting for larger fish. PSDs were positively associated with the presence and abundance of young-of-the-year bluegill and golden shiners (Notemigonus crysoleucas). Furthermore, crappie PSDs were positively associated with bluegill PSDs, while following a hyperbolic relationship with largemouth bass (Micropterus salmoides) PSDs. Growth was also related to the quantity and quality of forage present. Although forage likely affects growth and PSD of crappie, largemouth bass may also indirectly affect these parameters through predation and competition. White crappie populations with diverse size distributions should be achieved in flood prevention lakes by management of largemouth bass/bluegill populations.