Relationship between Morphometry of Excavated Floodplain Ponds along the Mississippi River and Their Use as Fish Nurseries

Abstract

Abstract We sampled ichthyoplankton, zooplankton, and juvenile fish during May, August, and November 1988 from 15 excavated floodplain ponds along the Mississippi River. In May, densities of larval shad Dorosoma spp. ranged from 1.1 to 87.8/m3 and densities of larval sunfish Lepomis spp. ranged from 0.3 to 19.3/m3 among ponds. Ponds with long (>1,800 m), sinuous shorelines, high volumes (>55,000 m3 ), and variable depth had high ichthyoplankton densities (>50/m3); smaller, low-volume ponds frequently had low ichthyoplankton densities (<10/m3). Ponds that sustained high densities of larval sunfish during May had high numbers of young-ofthe-year sunfish in August and November, which suggests that ponds with high ichthyoplankton densities ultimately contributed more fish to river populations. Pond morphometry probably did not affect food availability, because zooplankton densities were not correlated with ichthyoplankton densities and larval threadfin shad D. petenense grew faster in ponds with high shad den...