Reproduction takes place in the fall, as soon as the fish begin migrating to wintering grounds. Peak spawning activity occurs from early September through early November in water temperatures of 53 to 66 degrees F and at depths of 60 to 160 feet. The center of spawning activity occurs off the coasts of New York and New Jersey with less concentrated activity occurring in southern New England waters. The eggs float in the water column, hatching 72 to 75 hours after being laid. Summer flounder inhabit inshore areas during the warmer periods of the year.
Fluke prefer eel grass beds and wharf pilings because of the protection they offer.
In the summer, small and medium sized adults are found on the sandy and muddy bottoms of bays, harbors and along the open coastline. With the approach of fall, summer flounder migrate to more offshore waters in depths from 150 to more than 500 feet. The summer flounder, which depends upon sight to capture its food, feeds most actively during daylight hours. Juveniles feed upon small shrimp and other crustaceans, while adults eat a variety of fish, including small winter flounder, menhaden, sand lance, red hake, silversides, bluefish, weakfish and mummichogs, as well as invertebrates such as blue crabs, squid, sand shrimp, opossum shrimp and mollusks. Adults are very active predators, often chasing schools of small fish to the surface and leaping out of the water in pursuit of them.