Summer Flounder

The summer flounder (Paralichthys dentatus), commonly called fluke, is a left-eyed flatfish in the family Paralichthyidae native to the western Atlantic coast of North America. It is one of the most familiar coastal flatfish along the eastern United States and a popular sport fish throughout its range. Summer flounder occur from the Gulf of Maine south to Florida, with the greatest abundance found in the Mid-Atlantic region. The species is managed under cooperative U.S. fishery regulations, and while historically subject to overfishing pressure, stock assessments and management measures have aimed to maintain sustainable population levels.

Summer flounder can be identified by several key traits.

• Body: broad, oval, flattened, relatively deep-bodied for a flatfish
• Eyes: both on the left side (left-eyed flatfish)
• Coloration: mottled brown to gray-brown upper side with scattered dark spots and pale ocellated rings, which can vary to match substrate
• Mouth: large, with prominent sharp teeth, unusual among flatfish
• Size: typically 40-60 cm, occasionally larger Its large mouth with visible teeth and left-eyed orientation distinguish it from right-eyed species like winter flounder, while its variable mottled spotting differs from the more uniform coloration of other Paralichthys relatives.

Summer flounder inhabit coastal and estuarine waters along the western Atlantic, ranging from the Gulf of Maine and Nova Scotia south to the Florida coast, with the core of the population concentrated in the Mid-Atlantic Bight. They occupy sandy and muddy bottoms in bays, estuaries, and continental shelf waters, generally at depths from very shallow nearshore zones down to around 150 m. The species undertakes seasonal migrations, moving into shallow bays and estuaries during warmer months and offshore to deeper continental shelf waters in winter. Juveniles rely heavily on estuarine nursery habitats before joining the broader coastal population.

Summer flounder are active ambush predators, lying camouflaged on the bottom before lunging to capture fish, shrimp, and other invertebrates with their well-developed teeth. Unlike many flatfish, they are considered relatively aggressive hunters capable of chasing prey short distances off the bottom. They undertake seasonal inshore-offshore migrations, moving into shallow coastal bays and estuaries in spring and summer and retreating to deeper offshore waters in autumn and winter. Spawning occurs offshore in fall and winter, with pelagic eggs and larvae drifting inshore where they settle into estuarine nursery habitats. As both predator and prey, summer flounder play a notable role in coastal food webs.