Effects of Benthic Prey Composition and Abundance on Diet and Growth of Black Crappies in Three Florida Lakes

Abstract

The influence of benthic prey availability on growth of black crappies Pomoxis nigromaculatus is poorly understood due to scant research on the relationships between benthic prey abundance and composition and black crappie diet. However, benthic taxa play an important role as prey items of black crappies during intermediate ontogenetic diet phases. We evaluated diet, growth, and abundance of black crappies in three large Florida lakes (Lochloosa, Marian, and Monroe), and we related diets to benthic prey availability at these lakes. Black crappies in Lake Monroe obtained the largest size at age, whereas those in Lake Marian had the smallest size at age. Black crappies in Lakes Lochloosa and Marian consistently exhibited positive selection of dipteran pupae; fish in Lake Monroe showed consistently positive selection of a higher-quality prey item (the mysid shrimp Americamysis almyra) that was not available in Lakes Lochloosa and Marian. A similarity index indicated that benthic prey availability influenced consumption of benthic prey items by black crappies in all three lakes. Differences in prey availability (i.e., density and presence-absence) and prey selection influenced diet composition and ontogenetic diet shifts of black crappies. Diet and prey availability differences among lakes probably contributed to the variation in black crappie growth rates; the highest growth was observed at Lake Monroe, where the additional prey resource (A. almyra) was available.