Age and growth assessment of Chondrostoma regium (Heckel, 1843) (Teleostei: Cyprinidae) inhabiting the Zayandeh River (Iran) using different structures

This study investigated the age and growth of Chondrostoma regium in upstream of the Zayandeh River by using different calcified structures (i.e. scale, otolith and vertebra). Also, the potential variability of age and growth estimates derived from different structures and their competency for further applications in population and life history studies of this species were statistically evaluated and compared. Based on the aging performed by using different calcified structures, C. regium specimens composed of 4 age groups of 2 to 5 years. Considering all aging structures (i.e., scale, otolith and vertebra) the major proportion of the sample was those within the age groups of 3 and 4. The von Bertalanffy’s growth models of C. regium was fitted separately for the data derived from each of the aging structures. Among all the fitted models, the scale-based model showed the smallest measures of the information criteria with AIC=296.88 and SBC=300.86. Based on all the statistical indices for model comparison, the von Bertalanffy’s growth model using the direct scale-based observations showed the most reliability and the best performance for growth parameters estimation of C. regium in this study. Hence, for C. regium inhabiting upstream of the Zayandeh River the most statistically sound von Bertalanffy’s growth equation could be written as Lt=303 (1-e–0.11 ( t–(-0.34))). Given the importance of growth studies in effective management and conservation of native fish populations as well as considering the highly changing and under pressure environment of the Zayandeh River, our study attempted to provide updated information on growth characteristics of C. regium in this aquatic ecosystem. The results of this study may help to improve our understanding of its population dynamics and may provide help in designing better conservational plans for this native species.