Gadwall eat mostly submerged aquatic vegetation such as algae, grasses, rushes, sedges, pondweed, widgeon grass, and water milfoil, including leaves, stems, roots, and seeds. They also eat snails, midges, water beetles, and other invertebrates.
Gadwall are the third most hunted duck species (after Mallard and Green-winged Teal), with some 1.25 million of them harvested in 2020.