area it took about 2.5 days to sample each area (Schroeder and 

 Thompson 1987) . 



At the very least, the spatial distribution of turtles can 

 be described over a large area on a seasonal basis (Figure 3). 

 Areas of high turtle density have been defined based on these 

 surveys and future sampling could be reduced in scope to optimize 

 sampling when and where turtles are known to be present in 

 relatively large numbers to reduce costs. Turtle distributions 

 can also be classified by environmental correlates such as sea 

 surface temperature and depth when possible (Figure 4) . 



Estimates of relative abundance were completed and represent 

 the total number of loggerhead turtles of 2.5 feet or greater of 

 carapace length at the surface. These estimates were derived 

 from using line transect methods to estimate turtle density and 

 then multiplying density by total sampling area to estimate 

 relative abundance (Burnham, Anderson and Laake 1980) . 



To estimate absolute abundance requires corrections to be 

 made for significant effects of Beaufort Sea State, the 

 obliterating effect of sun glare and the average amount of time a 

 turtle spends at the water's surface. To estimate sea surface 

 time require the use of a radio tag on turtles of all size 

 classes greater than 2.5 feet throughout all seasons throughout a 

 species spatial range. This has yet to be done and therefore, 

 current estimates of abundance from pelagic aerial surveys remain 

 relative. 



Radio tracking remote sensincr ; While several studies have 

 been made on the use of radio and sonic transmitters with 

 turtles, the work conducted by the NMFS/SEFC will be used as an 

 example of the utility of this technique in describing surfacing 

 behavior and short range movements of turtles. Two independent 

 tracking experiments were completed using loggerhead and Kemp's 

 ridley turtles, respectively. 



In the first experiment, surfacing and movement 

 characteristics were determined for loggerheads over two four 

 week periods in the Cape Canaveral area off the east coast of 

 Florida. A radio transmitter float was towed by the turtles and 

 emitted standard radio signals while at the surface. A tracking 

 receiver was installed on an airplane and a Loran-C navigation 

 receiver provided positional information. The shape of the 

 transmitter float should be made to minimize drag and therefore 

 not interfere with or alter the animals normal swimming behavior. 

 The life of the transmitter is dependent upon the longevity of 

 the battery; the Cape Canaveral experiment lasted 30-45 days. 

 Twenty turtles were tagged and mean time at the surface was 

 estimated for hourly intervals. To evaluate sea surface time 

 truly, these experiments should be conducted over a species' 

 range throughout the year over all available size classes. 



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