NOTE Renaud et al: Activities of juvenile Chelonia mydas 



591 



5.06 km 2 for juvenile green turtles. Ogden et al. 

 (1983) found turtles moved up to 0.5 km between 

 feeding and resting sites, but they did not report 

 ranges of movement. 



Turtles appeared to select for the south jetty. Landry 

 et al. 3 also recorded many more turtle sightings 

 at the south jetty than at the north jetty. Of two 

 turtles caught at the north jetty, only one remained 

 there longer than two weeks. The other moved to the 

 south jetty during northerly winds in excess of 20 

 knots. Because of its accessibility, the north jetty 

 received much more use by the public than the south 

 jetty. The effect of this disproportionate use on turtle 

 presence or behavior, or both, during the study is 

 unknown. 



Submergence behavior 



Green turtle behavior was characterized by numer- 

 ous short submergences and surfacings. Sub- 

 mergences <5 min occurred mostly during dusk and 

 dawn when active periods of foraging were observed. 

 We felt this was a direct effect of the shallow habitat 

 occupied by the turtles. The transmitter antenna 

 could be exposed at times when the turtle was still 

 submerged. Submergence >10 min was observed at 

 night and minimally during the afternoon. 



Submergence durations by green turtles in our 

 study was similar to that for green turtles studied 

 by Renaud et al. 2 Eighty-nine to ninety-nine percent 

 of the submergences were <10 min in duration and 

 17-56% were <1 minute. Mean submergence times 

 for turtles in our study were considerably shorter 

 than the mean submergence times of Kemp's ridleys 

 found by Byles ( 1989) ( 18.1 min), and Mendonca and 

 Pritchard (1986) (16.7 min). This may be a result of 

 the different habitats and feeding behaviors of 

 Kemp's ridleys and the green turtles in our study. 

 Our turtles also were smaller than turtles in the 

 other two studies. 



The percentage of submerged time for each 24-h 

 day ranged from 80.8-97.8%. The turtles with the 

 three lowest percent submerged times were observed 

 for long periods with their antenna only partially 

 exposed. This behavior undoubtedly lowered their 

 submerged to surface ratio. Balazs (1994), through 

 satellite telemetry, found that two migrating adult 

 green turtles in the Pacific Ocean spent 95-96% of 

 their time submerged. Renaud and Carpenter ( 1994) 

 found percent submerged time to be 90.0-95.7% for 

 three satellite-tracked juvenile loggerhead turtles, 

 Caretta caretta, in the Gulf of Mexico. Two satellite- 

 tracked juvenile Kemp's ridley sea turtles, in the 

 Atlantic and Gulf of Mexico, had percent submerged 

 times of 94.0-98.6% (Renaud, in press). Byles ( 1989), 



studying adult Kemp's ridleys in the Gulf of Mexico 

 with satellite telemetry, found that they spent an 

 average 96% of the time submerged. A study of radio- 

 tracked loggerheads with 64.0-91.9 cm carapace length 

 (straight or curved not specified) in the Canaveral 

 Channel, Florida, revealed that they averaged 96.2% 

 of the time submerged (Kemmerer et al., 1983). 



