Impact of Threadfin Shad on Macrocrustacean Zooplankton in Two Arizona Lakes

Abstract

Analysis of data on macrocrustacean zooplankton in two Arizona lakes provided field evidence that large populations of threadfin shad (Dorosoma petenense) are capable not only of causing species shifts in zooplankton, but also of virtually eliminating zooplankton communities for extended periods as long as 2 years. Our analysis suggests that the long-term negative effects of stocking threadfin shad may greatly outweigh the short-term positive benefits to piscivores.