Some Biological Characteristics of Shemaya Chalcalburnus chalcoides, in Shirud River

This study was conducted to determine several biological characteristics such as age, growth, length-weight relationship, sex ratio, Gonadosmotic index and fecundity of immigrant population of Shemaya Chalcalburnus chalcoides in Shirud River from early April to July 2006. Age and growth determinations were made from scales from 412 fish ranging from 117.6 to 218mm total length. According to Von Bertalanffy’s growth function index, there was a meaningful difference between the growth rate of male and female fish. The sex ratio was found to be 2.4:1 (M:F) which was statically significant (P<0.05). The average length and weight in male fish was calculated as 150.6 mm and 24.7 g, respectively, whereas it was recorded at 175.7mm and 41.7g for female fish. Females (age groups II to V) were slightly longer than males (age groups I to IV). Even though, in case of length parameter there was a significant difference (P<0.05) between different sexes, however, in term of weight, no significant difference was observed between them. The peak of gonadosmotic index was recorded in May for Male fish and in early June for female fish. The average value of fecundity was calculated to be about 3900 eggs which made a meaningful correlation with body length and body weight. According to data, the egg diameters of these species were ranged between 1.05-1.17. In this study, it was concluded that, this population had greater growth factors in comparison with other population of the same species from other regions, mainly due to desirable biological parameters of Shirud River for immigration.