Larval Black Crappie Distribution: Implications for Sampling Impoundments and Natural Lakes

—An understanding of larval fish distributions is essential for developing an appropriate sampling design to monitor larval abundances. We monitored abundance of larval black crappie Pomoxis nigromaculatus to assess spatial differences in Richmond Lake (a 336-ha impoundment) and Brant Lake (a 405-ha natural lake), South Dakota, during 1994–1996. Age-0 black crappies were collected with a 500-mm mesh ichthyoplankton trawl from fixed sites within each water body. In the impoundment, larval black crappies were collected over a longer period at the upper site than at the dam site during 1994 and 1995. In the natural lake, larval black crappie abundances were similar between east and west sites during all 3 years. In light of our results, biologists should spatially stratify sampling sites when collecting larval black crappies in impoundments such as Richmond Lake, whereas random sites may be more appropriate in natural lakes such as Brant Lake. An understanding of larval fish distribution is essential in determining an appropriate sampling design to monitor larval abundance. Distributions of larvae vary temporally and spatially (Kelso and Rutherford 1996), and this variation should be considered when designing a study. Numerous studies have examined temporal and spatial variations of larval fishes in freshwater lentic systems (e.g., Werner 1969; Storck et al. 1978; Tuberville 1979; Faber 1980; Conrow et al. 1990). Mitzner (1987) examined spatial differences of larval (,15 d) crappies Pomoxis spp. in Rathbun Lake, Iowa. Although white crappies P. annularis and black crappies P. nigromaculatus are similar in a number of characteristics, several important differences exist between these two species. For example, temporal differences exist between larval abundances of white and black crappies, with larval black crappies consistently collected earlier than larval white crappies in southeastern Louisiana waters (Chatry and Conner 1980). In addition, juvenile white crappies primarily fed near the bottom, while juvenile black crappies fed near the surface in Rough * Corresponding author. 1 Present address: Texas Tech University, Department of Range, Wildlife, and Fisheries Management, Lubbock, Texas 79409, USA. River Lake, Kentucky (Overmann et al. 1980), which suggests that spatial differences in juvenile white and black crappies also exist. Because temporal and spatial differences probably exist between white and black crappies, a distributional assessment of larval black crappies was still needed. Thus, we monitored larval black crappie abundances to assess spatial differences in Richmond and Brant lakes, South Dakota, during 1994–1996.