Comparison of Length-frequency Analyses for Estimation of Growth Parameters for a Population of Green Turtles

We compared the ability of four length-frequency analysis programs to generate accurate von Bertalanffy growth parameters for a population of green turtles (Chelonia mydas) of known growth rates. The four programs were ELEFAN I, Shepherd's length composition analysis (SLCA), projection matrix method, and MULTIFAN. ELEFAN failed to identify a set of parameters that qualified as a best fit. The parameter estimates generated by SLCA successfully described six of the 10 length distributions from the population of green turtles. The parameter estimates produced by the projection matrix method failed to describe adequately any of the 10 length distributions. MULTIFAN generated a set of growth parameter estimates that successfully described all of the 10 length distributions. Although MULTIFAN had the best performance, it requires substantially more initial information and estimates than do the other programs. The best approach-particularly with a poorly studied population-may be to conduct initial analyses with SLCA, followed by analyses with MULTIFAN. Length-frequency analysis is a useful method for the study of growth in populations of immature sea turtles. Further study is required to determine whether these methods are appropriate for populations of sea turtles that include mature individuals.