Reproductive biology of female Oxynoemacheilus bergianus (Actinopterygii: Cypriniformes: Nemacheilidae) from the Jajrud River, the Namak Lake basin, central Iran

Loach fishes of the genus Oxynoemacheilus, are found in Iran and adjacent countries, but their reproductive parameters are barely known. The main aim of this study was to obtain reproductive characteristics of Oxynoemacheilus bergianus (Derjavin, 1934). Sampling was carried out at monthly intervals throughout the year and 279 individuals of O. bergianus were caught from the River Jajrud in the Namak Lake basin, central Iran. Age, fecundity, oocyte diameter and Gonado-Somatic Index (GSI) were examined. Regression analyses were used to find relations between fecundity and fish size, gonad weight (Wg) and age. The average egg diameter ranged from 142.8 micrometer (August) to 513.1 micrometer (March). Spawning took place in March, when the water temperature was between 16 and 20°C. The average GSI values for females at the beginning of the reproduction period (February) and in ripe mature females (March), were 9.8% and 22.4%, respectively. The averages of absolute and relative fecundity (relative to body weight) were 2792.4 eggs (SE±692.5) and of 637.9 (SE±119.6) per gram body weight, respectively. The absolute fecundity was significantly related to body weight and ovary weight. Based on the pattern of GSI, it was concluded that this fish has a relatively prolonged active reproductive period. The present knowledge could be used in the conservation and management strategies intended to maintain the O. bergianus stock.