Adults spawn in the winter and tend to return to the same spawning grounds year after year.
Flounder mature at an earlier age in the southern part of their range. Females usually produce between 500,000 to 1.5 million eggs but up to 3.3 million have been reported. Temperature and salinity appear to control survival of eggs during the two to three months of larval development. Larvae settle to the bottom as juveniles about six to ten after hatching. Predatory fish such as striped bass and bluefish, birds, invertebrates, and marine mammals prey on the larvae and juveniles.