PLASMA-CORTICOSTERONE CONCENTRATIONS ASSOCIATED WITH ACUTE CAPTIVITY STRESS IN WILD LOGGERHEAD SEA-TURTLES (CARETTA-CARETTA)

Plasma corticosterone concentrations were measured in wild loggerhead sea turtles (Caretta caretta) in response to acute captivity (capture, serial bleeding, and restraint up to 6 hr). In general, concentration s of corticosterone dramatically increased 1 hr after capture, peaked at 3 hr, and decreased by 6 hr. Initial corticosterone concentrations were significantly lower in animals captured by tangle net than in tho se captured by trawl and were thought to more closely represent baseli ne levels. Significant effects of season and size class on corticoster one concentrations were found for turtles captured by trawl. Corticost erone concentrations of small turtles captured in summer were higher t han those of large turtles captured in the same season and of all turt les captured during winter. In winter, corticosterone concentrations f or small turtles were higher than those for large turtles at 3 hr afte r capture. Large turtles captured during winter experienced the slowes t rate of increase in plasma corticosterone and a decline at 3 hr afte r capture. Although cloacal temperatures were significantly higher in summer samples, corticosterone concentrations of large turtles did not differ between seasons until 1 hr after capture. In addition, several large turtles during summer did not experience an increase in cortico sterone concentrations 1 hr after capture. It is possible that the low er corticosterone response of large turtles captured during summer may be associated with reproductive condition. (C) Academic Press, Inc.