Field studies using tagging and recapture techniques with displaced fish were employed to demonstrate a significant exchange of winter flounder, Pseudopleuronectes americanus, between two areas of Narragansett Bay separated by a natural constriction and earth sill. The tagging studies also provided information on movement, exploitation rates, and sex ratios of the winter flounder. A mathematical model derived from the heat diffusion equation was utilized to suggest that a relatively short search time would be required by winter flounder to locate a hurricane-barrier opening when empirical values for model parameters were utilized. It is concluded from the tagging studies and from theoretical considerations that the proposed hurricane protection devices will not act as physical barriers to fishes which use the bay for spawning or feeding.