Winter flounder drawing.
Winter flounder drawing.
Courtesy: Maine Department of Marine Resources

Winter Flounder (Pleuronectes americanus)

Alternate common name: Blackback Flounder, Georges Bank Flounder.
Color: Adults vary in color from shades of dark brown to gray or olive green; may have mottled blotches and light specks. Juveniles are lighter and have more spotting.
Size: Average about 12 inches long.
Habitat: Open water, muddy and sandy bottom.
Seasonal appearance: All year; most common in winter.


The body of the winter flounder is oval-shaped, flat, and thick. Beginning life with eyes on both sides of its head, after a few weeks, the left eye migrates to the right side of the body. The eyes remain close together on the upper side of the fish. The left, or blind side, of the fish is white and faces the bottom. Unlike other Rhode Island flounder, winter flounder have rough scales and a small mouth, with thick, puckered lips and small rows of slightly rough, flattened teeth. Winter flounder can change color to blend in with the bottom type, but generally are much darker than most other flatfish.

Critter Fact Flounders with both eyes on the right side of their bodies are referred to as "right-eyed" flounder.

Life History and Behavior

Narragansett Bay and coastal salt ponds are important spawning areas for winter flounder. Mature adults migrate from deeper waters in the Bay, Rhode Island Sound, and Block Island Sound into shallower waters during the late fall. Spawning occurs in the Bay from late December into April. Females deposit clusters of sinking eggs in slow-flowing coves and embayments. Juvenile fish remain in shallow nursery areas for two to three years before migrating to deeper water. Winter flounder are the only Rhode Island flatfish that spend their entire early life in the estuary.

Winter flounder prefer sandy or muddy bottoms, and are sometimes found near eelgrass beds, but can also be found on many other bottom types. They are omnivores and feed on sand shrimp, amphipods, larval fish, mollusks, worms, and some types of seaweeds and plants.

Fishery Note The New England Fishery Management Council and the Atlantic States Marine Fisheries Commission manage the winter flounder fishery for conservation of the species and longevity of the fishery.

Special Notes

Adapted from The Uncommon Guide to Common Life on Narragansett Bay. Save The Bay, 1998.