Southeast Fisheries Science Center (U.S.)

Aerial surveys were conducted over U. S. Atlantic coastal writers south of Cape Hatteras and in the U. S. Gulf of Mexico from the Mexican border to approximately Cape St. George to estimate bottlenose dolphin abundance. Atlantic regional surveys, conducted in winter 1992, covered the continental shelf from Cape Hatteras to mid-Florida. Gulf of Mexico regional surveys, conducted in autumn of 1992 and 1993, covered approximately the western two-thirds of U.S. Gulf of Mexico bays, sounds and continental shelf. Line transect analytical methods were employed to model the probability density function for each survey stratum and estimate dolphin density which was extrapolated to abundance. Estimated bottlenose dolphin abundance in the U.S. coastal Atlantic survey area from Cape Hatteras to mid-Florida during the winter was 12,435 dolphins with a log-normal approximate 95% confidence interval (95% CI) of 9,684 - 15,967 bottlenose dolphins. Bottlenose dolphin abundance in the City of Mexico combined bay and sound survey strata was 3,554 dolphins (95% CI = 2,924-4,319). Estimated bottlenose dolphin abundance in the Gulf of Mexico coastal survey stratum was 7,690 dolphins (95% CI = 5,749 - 10,286), the Gulf of Mexico outer continental shelf survey stratum contained an estimated 22,496 bottlenose doohins (95% CI = 17,520 - 28,885).

Technical Memorandum