Factors Related to Black Crappie Occurrence, Density, and Growth in Florida Lakes

Abstract

Occurrence, density, and length at age of black crappie Pomoxis nigromaculatus were described from aquatic macrophyte densities, chlorophyll-a concentrations (CHLA), chlorophyll-a values adjusted to include nutrients encompassed in macrophytes (ACHLA), and zooplankton abundance in each of 60 natural Florida lakes. A logistic regression equation predicted 90% of black crappie occurrence from log₁₀lake surface area and log₁₀CHLA. Probability of black crappie occurrence increased with both variables. Density of black crappies was positively related to zooplankton abundance although highly variable, and it was unrelated to lake surface area, CHLA, ACHLA, or macrophyte abundance. Length at age 3 was quadratically related to fish density but was unrelated to trophic indicators (CHLA, ACHLA, zooplankton abundance), lake surface area, or macrophyte abundance. Lakes with the most promise for sustaining high catch rates of harvestable-sized black crappies were relatively large (>100 ha), contained high levels of CHLA (>10 μg/L), and had relatively high black crappie densities (>200 fish/ha). Low-density populations exhibited rapid growth but would probably provide low catch rates to anglers. Small (<10 ha), oligotrophic (CHLA < 3 μg/L) lakes were characterized by low frequency of black crappie occurrence. Growth and density of black crappies were not strongly affected by the presence or density of aquatic macrophytes. Potential effects of fish density on growth rates should be considered in managing black crappie populations.