Estimation of survival rates of loggerhead sea turtles ( Caretta caretta ) in Japan using a novel framework

Loggerhead sea turtles are an endangered species, and effective management requires accurate survival estimation. Narrow -interval estimates are particularly necessary in Japan because the available survival estimates have intervals that are too wide to allow comparison with estimates from other regions. Catchcurve analysis is a method for survival estimation and has limitations in that the existing framework cannot consider growth curve errors and sea turtle immigration. However, catch -curve analysis does not suffer from the requirement for intensive research efforts compared with mark -recapture analysis. Therefore, in this study, a new estimation framework was developed that can account for growth curve errors and turtle immigration, and the population parameters of loggerhead turtles ( Caretta caretta ) in Muroto, Japan between July 2002 and November 2009 were estimated. Using the developed framework, the survival rate was estimated as 0.852 year -1 (95% highest -density interval: 0.799-0.903). Compared with the Baja California loggerhead population, the results suggest that the survival rate after immigration to Japan is lower than that before immigration. For loggerhead sea turtles, which generally exhibit higher survival rates as they grow, this result suggests the presence of factors such as bycatch that increase mortality around Japan.