Life history pattern and feeding habits of Gobio bulgaricus (Drensky, ۱۹۲۶) (Pisces: Gobionidae) in an endorheic stream (Istranca Stream, Turkey)

The Aegean gudgeon Gobio bulgaricus (Drensky, ۱۹۲۶) is a freshwater fish species restricted to the western parts (Thrace) of Turkey. The aim of the present study is investigating key parameters such as age, growth, reproduction and feeding habits of G. bulgaricus in the Istranca Stream to determine biological characteristics of the species. During monthly samplings from March ۲۰۱۲ to June ۲۰۱۳, G. bulgaricus specimens were collected from the endorheic Istranca Stream, which is draining to the Lake Durusu in İstanbul. The results showed that the lifespan of the species was ۵ years. The length–weight relationships of G. bulgaricus indicated positive allometric growth and the relationship was lnW=-۳.۹۷۶+۳.۰۸۰lnSL for females, lnW=-۴.۰۰۸+۳.۰۸۸lnSL for males and lnW=-۴.۰۴۹+۳.۱۱۸lnSL for all individuals. The mean size at first sexual maturity (Lm) was ۴.۰۳ cm SL for females and ۳.۹۴ cm SL for males. Absolute fecundity ranged from ۳۵۵ to ۵۵۵۶ eggs with mean of ۱۱۷۹±۱۵۲ eggs. Prey analyses of digestive tract content indicated that G. bulgaricus was largely omnivorous (more precisely insectivorous) feeding mainly on aquatic insects and a small amount of plant and animal materials. Diptera larvae (IRI%=۹۶.۴۹) were the dominant prey of G. bulgaricus in terms of index of relative importance. It is considered that the present results will increase our knowledge of the life-history traits and feeding of G. bulgaricus.

Keywords:

Age , Diet , Growth , Reproduction , Istranca Stream , Turkey