Life-history traits of Cobitis splendens Erk'akan, Atalay-Ekmekçi & Nalbant, 1998 population in Çayağzı Stream (Akçakoca-Düzce, Turkey)

Turkey has a very rich freshwater fish fauna in terms of diversity and endemism. However, this richness is threatened by some factors such as pollution, habitat loss, invasive species, and overfishing. Cobitis is a small benthic freshwater fish genus distributed in the Western Palearctic. Cobitis splendens is endemic to the Melen and Akçakoca drainages in the Western Black Sea basin. Despite the fact that it is threatened by habitat loss and pollution in its native range, there has been no studies on the population structure and life history of the species. Therefore, within this study, population parameters and the life history characteristics of C. splendens were examined based on individuals collected from its native habitat. In this study, 227 C. splendens individuals were collected from Akçakoca Çayağzı stream between March 2019 and December 2019 using an electrofishing device. The length, weight, age distributions, age-length, age-weight and length-weight relationships, condition factor and sex ratio of specimens were examined. In addition, gonadosomatic index, egg diameter and fecundity of the studied population were estimated to determine reproductive characteristics The total length of the examined specimens ranged between 37.35 and 99.79 mm and their total weight ranged between 0.249 g and 6.386 g. Although the maximum age of individuals in this population is four years, 0-year-old individuals could not be sampled. The sex ratio of the whole sample was calculated as 1:1.05. According to the data obtained from GSI and egg diameter, it was determined that the breeding period of the population is between April and June.