Main Growth Parameters of a Threatened Species Chondrostoma holmwoodii (Boulenger, 1896) from Tahtalı Reservoir, İzmir, Turkey

A diverse genus of the Cyprinidae family, genus Chondrostoma Agassiz, 1832 has a wide distribution. More than half of the species distributes in Turkey, however there is little biological information about them. The aim of this study is to investigate the population parameters of Eastern Aegean Nase Chondrostoma holmwoodii and to evaluate the risks for the species in Tahtalı Reservoir. Fish sampling was carried out at 8 different sampling points at Tahtalı Reservoir in 2014 with multimesh gillnets. Population parameters such as age and sex composition, length frequence analysis and von Bertalanffy growth function were investigated. A total of 215 specimens of C. holmwoodii was sampled. Total length of the specimens varies between 4.3 - 28.2 cm and total weight 1.05 - 271 g. Age composition of the sampled specimens varies between 0 to V and most of the specimens were age-III. The von Bertalanffy growth parameters for C. holmwoodii was estimated as; L∞= 395.30 mm (SD=63.80), K=0.17 (SD=0.05) and L0=46.45 mm (SD=9.41). In conclusion, main problem for C. holmwoodii population in Tahtalı Reservoir is predation risk by Perca fluviatilis Linnaeus, 1758. In order to offer conservation strategies for C. holmwoodii Tahtalı Reservoir population, diet, population structure, and life history traits of P. fluviatilis need to be studied in detail.