Age and growth of Alburnus mossulensis Heckel, 1843 in Azad Dam Reservoir and Komasi River in Kordestan Province, Iran

Abstract

The aim of the present study was to estimate the population parameters including length-weight relationship (LWR), condition factor (KF), relation condition factor (Kn), age, growth and mortality of Alburnus mossulensis in Azad dam and Komasi River in Kordestan Province, Iran. Of 522 specimens, the fork length, total length and weight of A. mossulensis ranged from 70 to 164, 75-175 mm, and 4.3 to 48.1 g and averaged (±SD) 114.0 (±15.97), 127.5 (±25.29) mm and 18.2 (±5.61) g, respectively. The length-weight regression was W=0.0003×FL2.7434 indicating a negative allometric growth. The sex ratio (M:F) was 1:0.49, for adult A. mossulensis (n=134) which differed significantly from the expected 1:1 ratio (p<0.001). The von Bertalanffy growth parameters were estimated as L∞=170.3 mm, K=0.46 yr-1, t0=-0.59 yr. The instantaneous coefficient of natural mortality was estimated as 0.85 yr-1. The average of condition factor (KF) was 1.27(±0.161). Statistically significant differences were found in KF during different seasons (p<0.001). There was a significantly negative correlation between FL and KF (r2=0.60). The average of relative condition factor (Kn) was 1.06±(0.130). In the present study, the Kn of A. mossulensis were close to 1 and greater than 1 in Komasi River and reservoir, respectively. These results suggested the well-being of the fish was good in Azad Dam region.