Age, growth and spawning season of Luciobarbus esocinus Heckel, ۱۸۴۳ in Gamasiab River, Iran

In the current paper reproductive strategy and growth rates of Luciobarbus esocinus were investigated from ۲۰۱۰ to ۲۰۱۲, in Gamasiab River, Kermanshah, Iran. Samples were collected seasonally by gillnet and electro-fisher device. Sex ratio was evaluated from ۱۶۲ individuals and the percentage of male and female individuals were ۵۴.۷۶% and ۴۵.۲۴% respectively. Age structure was distributed between I and V and most frequency numbers for males and females belonged to II and IV age group, respectively. Length-weight relationship was computed as W=۸E-۰۵TL۲.۶۵۴۶ for all individuals. Mean total length and weight was ۳۳۳.۸۲±۱۳.۱۰ mm and ۲۹۷.۶۷±۴.۸۵ g for males, and ۳۷۱.۵±۲۱.۱۷ mm and ۳۰۷.۸۵±۷.۶۴ g for females. The von-Bertalanffy growth models of L. esocinus were described as Lt =۳۵۷.۱۴×[۱-e (-۰.۷۷× (t –۰.۰۹۰))] for males, Lt =۳۶۷.۰۲×[۱-e (-۰.۷۸× (t –۰.۰۹۴))] for females and Lt =۳۶۳.۵۷×[۱-e (-۰.۷۶× (t –۰.۰۸۷))]for both sexes. Results indicated that growth factors were highly similar in spring, summer and winter. CDA analysis revealed that the total and gonad weight are the main factors in discriminant analysis. The highest GSI values were found in spring for females and winter for males, however, it decreased rapidly after spring in females. Maximum growth rates were observed in early ages (I-II) and depleted with ages. K value and L∞ were determined as ۰.۷۷±۰.۰۹ Y-۱ and ۳۵۷.۱۴±۱۰.۳۸ mm for males and ۰.۷۸±۰.۲۴ Y-۱ and ۳۶۷.۰۲±۲۴.۱۵ mm for females, respectively. In conclusion this study provided basic information for stock assessment and management of L. esocinus in Gamsiab Reservoir.

Keywords:

Life-history styles , Reproduction , Mangar , Iranian inland waters