Seasonal and Size-Related Changes in the Diet of Northern Pike from a Shallow Prairie Lake

Food habits of northern pike (Esox lucius) were documented in Lake Thompson, a shallow, windswept, eutrophic lake in eastern South Dakota. The primary food items, assessed with the Relative Importance Index, eaten by northern pike were common carp (Cyprinus carpio), crappies (Pomoxis spp.), and fathead minnows (Pimephales promelas). Common carp were eaten in midsummer and winter. Crappies were eaten primarily in the winter. Fathead minnows were an important food source throughout the year. Macroinvertebrates were consumed by northern pike up to 600 mm throughout the open-water months. Northern pike in the smaller length groups (401–500 mm, 501–600 mm) ate primarily fathead minnows, juvenile common carp, and macroinvertebrates. Diets of larger northern pike consisted primarily of larger common carp, juvenile crappies, leopard frogs (Rana pipiens), and occasionally walleyes (Stizostedion vitreum).