The Iowa Department of Natural Resources says their most recent survey found the number of gizzard shad in the Iowa Great Lakes is up. Fisheries biologist Andrew Carlson says the fish have been in the Little Sioux River drainage to the south, but until recently hadn’t moved as far north as the lakes.
He says they’ve been found in rivers throughout the Midwest, but they are susceptible to large die-offs in cold conditions on ice over lakes.
Carlson says gizzard shad eat zooplankton in the lakes that other more desirable species rely on. That’s why they are keeping an eye on the population.
Carlson says the positive is smaller gizzard shad can be a food source for the top game fish.
Carlson says the gizzard shad may have entered the Great Lakes in the 2024 flood.
He says the D-N-R has been doing shoreline surveys on Spirit Lake, East Lake Okoboji and West Lake Okoboji at fixed standardized sites every year since 1989.
