The fluke fish, commonly known as summer flounder, is a flatfish found along the Atlantic coast.
Defining the Fluke Fish
The fluke fish is scientifically classified as Paralichthys dentatus, a member of the family Paralichthyidae. This species belongs to the group of “left-eyed” flounders, meaning both of its eyes are situated on the left side of its head as an adult. As a flatfish, the fluke is characterized by its laterally compressed body, an adaptation that allows it to live primarily on the seafloor, lying on its right, unpigmented side.
Key Physical Characteristics
The summer flounder possesses a remarkably flattened body, which is a defining feature among flatfish. This unique eye placement allows the flounder to observe its surroundings while resting on the ocean bottom.
The fish exhibits an extraordinary ability to change its coloration, earning it the nickname “chameleon of the sea.” Its upper surface typically ranges from brown to gray or drab, often adorned with five to fourteen ocellated, or eye-like, spots, frequently arranged in an “X” pattern, while its underside remains white. This camouflage enables it to blend seamlessly with the sandy or muddy substrates where it resides.
Adult summer flounder typically measure between 15 and 20 inches in length and weigh 1 to 2 kilograms, although females can reach up to 1 meter and weigh over 7 kilograms. They possess a large mouth equipped with sharp, well-developed teeth, indicative of their predatory feeding habits.
Habitat and Life Cycle
Summer flounder inhabit a broad range of marine environments, favoring sandy or muddy bottoms in coastal waters, estuaries, and offshore depths. Their geographic distribution spans from Nova Scotia, Canada, southward to the east coast of Florida, with their highest abundance concentrated in the Mid-Atlantic region between Massachusetts and North Carolina. These fish undertake significant seasonal migrations, moving inshore into shallow coastal waters and estuaries during late spring and summer as water temperatures rise. Conversely, they migrate offshore to deeper, warmer waters along the continental shelf in the fall and winter months.
Its eyes, initially positioned on opposite sides of its head during the larval stage, undergo a significant metamorphosis, with the right eye migrating to the left side as the fish matures. Spawning occurs offshore during the fall and winter, typically peaking in October and November. Female flounders are highly prolific, releasing 460,000 to over 4 million eggs into the water column.
After hatching, the larvae, which initially resemble conventional fish with an eye on each side, drift with ocean currents towards coastal areas and estuaries. During this larval stage, a remarkable metamorphosis takes place, usually around three weeks post-hatching, as the right eye gradually migrates to the left side of the head, and the fish assumes its characteristic flattened, bottom-dwelling form. Juveniles then spend their first year in these inshore nursery grounds before some join the adult offshore migration. Summer flounder reach sexual maturity at approximately two to three years of age.
Ecological Role and Culinary Significance
Summer flounder function as active ambush predators. They often lie partially buried in the seafloor, utilizing their camouflage to await prey. Their diet consists of smaller fish such as sand lance, menhaden, and bluefish, along with crustaceans like shrimp and crabs, and squid. While adept at ambushing, they are also capable of rapid bursts of speed to actively pursue faster-moving prey. Larval and juvenile flounders are preyed upon by species including spiny dogfish, cod, and hakes, while larger sharks, rays, and monkfish target adult summer flounder.
Summer flounder hold considerable culinary and economic importance. They are a popular food fish, prized for their lean, white, and flaky flesh, which offers a mild and delicate flavor. This makes them a popular choice for both commercial and recreational fishing along the Atlantic coast.
In 2023, commercial landings of summer flounder totaled 11 million pounds, valued at approximately $24 million. Recreational anglers also heavily target summer flounder, with landings reaching 8.6 million pounds in 2023. The management of the summer flounder fishery is a cooperative effort involving NOAA Fisheries, the Mid-Atlantic Fishery Management Council, and the Atlantic States Marine Fisheries Commission, which allocate the catch between commercial and recreational sectors.