Length- weight relationship and condition factor of Squalis cephalus (L., 1758) in Shohadaye Songhor Dam reservoir in Kermanshah province

This study was conducted to investigate length-weight relationship and determine condition factor of Squalis cephalus in Shohadaye Songhor Dam reservoir in Kermanshah province. To this end, 113 specimens were caught by gill net with the mesh of 2 to 5 centimeter between July 2011 and December 2011, on a monthly basis. The age range of 2 to 6 were observed in this population and the sex ratio (M: F) was determined 1:0.24. The total length of male and female specimens ranged between 167-281 and 211-254 mm, and the total weight of males and females were ranged from 62-317 to 115-240 gr, respectively. The mean condition factor of males (1.65±0.18) was higher than that of females (1.63±0.13), but the differences between sexes were not statistically significant. The calculated length-weight relationship for this species could be explained by the following equation for male, female and population: W=7e-06L3.112, W=4e-05L2.83 and W=9e-06L3.08, respectively. According to b index amounts in females (b=2.82) and males (b=3.12), the growth pattern for this fish is reported negative isometric and allometric growth for males and females, respectively. As a result, it was observed that fish in Shohadaye Songhor Dam Lack attained higher length compared to the fish of the same age range in other water resources. This may be an indication of better ecological condition and higher food supply in Shohadaye Songhor Dam reservoir.