Seasonal Distributions and Abundances of Loggerhead and Leatherback Sea Turtles in Waters of the Northeastern United States

摘要: Seasonal distributions and abundances of loggerhead (Caretta caretta) leath- erback (Dermochelys coriacea) sea turtles in continental shelf waters off the coast northeastern United States were derived from more than three years aerial shipboard surveys. There 3460 turtle sightings, including 2841 loggerheads, 128 leatherbacks, 491 unidentified. Relative abundance patterns, corrected for uneven distribution survey effort, demonstrated an extensive area near Long Island, New York, along mid-shelf to Cape Hatteras, North Carolina. Areas high relative leatherbacks scattered, with clusters south Island central eastern Gulf Maine. Loggerheads occurred significantly farther (x = 38?20' N) 40005' N), warmer (mean surface temperatures 22.2 C 20.4 C, respectively). The two species did not differ water depth or bottom slope at sighting; modal interval both was 21-40 m. Patterns concentration differed greatly nearly all marine mammals, suggesting little overlap resource utilization. Both absolute density estimates much higher loggerheads. Overall mean densities 21.6 loggerheads per 1000 km track, 6.85 km. Absolute estimates, 454 special surveys, ranged 1.64 x 10-3 5.10 10-1 km-2 2.09 2.16 10-2 km-2. maximum values reported Mexico Florida shore. Total study populations during summer estimated 2200-11,000 100-900 leatherbacks. These are minimal because they based on observations surface, may represent greater abundances. patterns this analysis could be used as a basis designation critical habitat U.S.