Age-0 Black Crappie Abundance and Size in Relation to Zooplankton Density, Stock Abundance, and Water Clarity in Three Florida Lakes

Abstract.-Crappies Pomoxis spp. are popular sport fishes but are often difficult to manage due to highly variable recruitment. To assess the factors influencing recruitment, we investigated the size and abundance of age-0 black crappie P. nigromaculatus in relation to zooplankton density, adult stock abundance, and water clarity in three productive Florida lakes. Age-0 black crappies were collected at Lakes Wauberg, Lochloosa, and Tarpon by use of surface and bottom trawls during the spring, summer, and fall of 2000 and 2001. Zooplankton abundance was measured concurrently with trawl sampling. Early-summer juvenile abundance was positively related to stock abundance during the previous fall among lakes, indicating a relationship between stock size and juvenile black crappie abundance. Early-summer juvenile abundance was positively related to juvenile abundance in the fall (i.e., at the end of the first summer), suggesting that year-class strength was set by early summer in all lakes. Lake Lochloosa had the highest crustacean zooplankton abundance in both years, but this lake had the smallest age-0 black crappie size and intermediate age-0 fish abundance. Thus, we found no relationship between crustacean zooplankton density and black crappie size across lakes. Reduced Secchi depths due to high chlorophyll-a values and wind resuspension of sediments may have reduced feeding efficiency for age-0 black crappies at Lake Lochloosa relative to the other lakes. Age-0 black crappie abundance and size during fall were not predicted solely by food availability, stock abundance, or water clarity, suggesting that these factors interacted to influence recruitment through the first year of life