Filter-Feeding Rates of Gizzard Shad

Abstract

Abstract In laboratory feeding trials, gizzard shad Dorosoma cepedianum of 5.3–17.5-cm standard length fed on zooplankton as pump filter feeders, collecting prey by a series of rapid suctions not directed at individual prey. Buccal volume, determined from plaster casts, increases as a power function of fish standard length. Pumping rates decrease exponentially with length. A model of filtering rate, the product of buccal volume and pumping rate, was corroborated by feeding trials in which gizzard shad cleared zooplankton from a pool. By this model, absolute filtering rates increase as a power function of fish length while filtering rate per gram of fish decreases as a power function of length. Populations of gizzard shad can filter substantial volumes of lake water each hour.