SEYDİSUYU (SAKARYA HAVZASI-ESKİŞEHİR)’NDA ENDEMİK OLARAK BULUNAN Squalius pursakensis (HANKÓ, 1925)'İN BİYO-EKOLOJİK ÖZELLİKLERİNİN İNCELENMESİ
In this study, some important bio-ecological features and habitat preferences of endemic Squalius pursakensis living in Seydisuyu (Sakarya Basin – Eskişehir) between April 2011 and July 2013 were determined. Length, weight and sex of dissected fish specimens were determined, then eggs were counted, and the diameter of scales was measured. Fecundity, egg diameter distributions, various growth indices, spawning duration and time, sex ratio, size at maturity, habitat choices and relative condition factor were calculated. Data derived from 1684 individuals sampled in the field studies indicated that age varied between 0 and XII, minimum and maximum total length and weight values were 46 mm and five g., and 445 mm and 1263.5 g, respectively. Sex ratio was male-biased (female:male ratio = 0.63:1); male ratio was 61% and female ratio was 39% for 949 individuals in total. Growth indices examined for S. pursakensis showed variable growth rates and relative condition values amongst the sampling stations. For all sampling stations, spawning time extended from early April to late June and multiple spawning events were observed. Age at maturity was two years in all the sampling stations. Total and relative fecundity (by total length) varied between 280 and 112530, and 4.32 and 583.06, respectively. Habitat preference analyses suggested that the species preferred habitats with shadow, lower light intensity, plant and ligneous areas, lower or medium flow, small stones and silt.