FIG 3.

Concentrations of V. vulnificus in oysters (A) and clams (C) and concentrations of V. parahaemolyticus in oysters (B) and clams (D), according to the time of year of sample collection. Vertical lines in panels A and B, the dates of the opening (15 October) and closing (31 March) of the oyster season in North Carolina. Horizontal lines, concentration of bacteria that the FDA considers nondetectable in oysters. Gray boxes, times of the year when the shellfish are in season and there are Vibrio concentrations greater than the FDA nondetectable level. The actual limit of detection was log 1 CFU/g. Values below the limit of detection were assigned a value of log 0 CFU/g.