Growth model for the endangered cyprinid fish Tribolodon nakamurai based on otolith analyses

Abstract

A growth model for the endangered cyprinid fish Tribolodon nakamurai was derived following otolith analyses of 16 wild and 53 reared specimens. The asteriscus was the most appropriate to measure size among three otolith elements, and its height OHmm was used as size index of otolith. Standard length L cm was best back-calculated using the Gompertz model, L= 70.0.exp[-exp{-0.553 (OH-2.73)}]. Translucent zones on the lapilli, analyzed from 5-year-old-reared fish, were regarded as winter slow-growing zones. The ages of 10 wild specimens of 37.0-48.1 cm standard length were calculated as 7-10 years by counting the translucent zones on the lapilli. Age t was best back-calculated using the allometry model, t= 1.33·OH1.37. The growth trajectory of T. nakamurai followed a slender S curve, three typical growth models, von Bertalanffy, Logistic and Gompertz, and Richards' model, which is a general formula of the above three, being fitted using the maximum likelihood method. The Gompertz model, Lt=60.2·exp[-exp{-0.258(t-4.68)}], was found by Akaike's information criterion (AIC) to be the statistically most acceptable growth model.