 Adult winter flounder are opportunistic sight-feeders that target annelids, crustaceans, bivalves, and fish depending upon prey availability.Winter flounder reach sexual maturity at about two to three years of age and a total length of 25–30 cm, with variance across their range.Mature adults (excluding those on Georges Bank) generally migrate in two phases, where adults enter shallow estuaries in the late fall and early spring to spawn in late winter or early spring before returning to deeper parts of the estuary or offshore waters.