Gizzard shad ( Dorosoma cepedianum ) expansion and reproduction in the Upper Colorado River Basin

Gizzard shad ( Dorosoma cepedianum ) were introduced into the Colorado River Basin circa 1996 via an unintentional contaminated stocking. Gizzard shad were collected throughout much of the Upper Colorado River Basin in 2005, 2006, and 2007. These collections document a rapid range expansion of this introduced species and a threat to intact fisheries.