Feeding,growth, and particle-size-conversion efficiency in white sucker larvae and young common shiners

Synopsis Instantaneous feeding, assimilation, and growth rates for white sucker larvae and young common shiners and guppies (1–2 mg initial dry weight) were measured. Food consisted of natural zooplankton. Linear relationships were obtained between growth and feeding rates for instantaneous feeding rates up to 0.5 mg^-1 day^-1. Maximum gross conversion efficiencies (K₁) were 0.26, 0.31, and 0.24 for suckers, shiners, and guppies respectively. Particle-size-conversion efficiency (-log K₁ per log predator-prey size ratio) was 0.15 for suckers, 0.14 for shiners, and 0.18 for guppies. These values are lower than most available estimates of particle-size-conversion efficiency for carnivorous zooplankton and piscivorous fish, indicating that young planktivorous fish are among the most efficient predators at transferring biomass up the biomass size spectrum in aquatic ecosystems.