The gizzard shad, Dorosoma cepedianum, is a nonnative fish that has been introduced to Willard Bay Reservoir, where its young serve as a forage fish for walleye, wiper, and other sport fish. The species is relatively new to Utah; it was first introduced to Willard Bay Reservoir in 1990. The population in the reservoir grew rapidly, however, and is now thriving. In addition to the Willard Bay population, gizzard shad were recently accidentally introduced to the main-stem Colorado River drainage, and the species now occurs in Lake Powell.
Gizzard shad are native to the Great Lakes area and south through the central United States. The species eats invertebrates, primarily zooplankton, which are filtered from the water. Gizzard shad are extremely prolific, with females producing hundreds of thousands of eggs each year.