SUMMARY 



Aerial surveys of marine mammals, birds, and turtles were conducted at four 

 subunits of the Gulf of Mexico from August to December 1979. This Pilot Study was 

 designed to develop techniques and to collect preliminary data on the vertebrate faunas 

 of outer continental shelf (OCS) waters. This information, once expanded to include an 

 adequate sample size, will be important to evaluating effects of oil and gas development 

 in offshore areas. 



Surveys were conducted at altitudes of 91 and 228 m. The 91-m surveys were 

 superior for detecting and identifying birds and turtles, while more area could be 

 surveyed for larger animals at 228 m. Waters within 111 km of shore were sampled at a 

 3:1 ratio in relation to waters 111 to 222 km offshore. Texas subunits extended beyond 

 the continental shelf, but Florida subunits did not. Observations were made on 12 

 mammal, 35 bird, and 5 turtle taxa. Sperm whales were documented in waters off 

 Texas. Marine turtles were common in the eastern Gulf but virtually absent from the 

 western areas studied. Differences in dolphin faunas in the eastern and western subunits 

 were noted and potential north-south movements in response to season were noted on 

 both sides of the Gulf of Mexico. 



The maps and basic ecological data collected provided a unique view of faunal 

 differences within OCS areas of the Gulf of Mexico. Because of the complexity of the 

 Gulf of Mexico and its fauna, additional analyses will depend upon having data 

 encompassing annual, seasonal, geographic, and bathymetric variation. 



Additional survey areas and more frequent samples emphasizing seasonal variation 

 on successive years are required for making more accurate conclusions and effective 

 management decisions relevant to OCS development. 



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