New data on the biology of Cobitis cf. satunini from the southern Caspian basin (northern Iran)

Abstract

Little is known of the life history of Cobitis cf. satunini, a loach species native to the Caucasus and southern Caspian Basin. Life history characteristics of this species were examined in 568 specimens collected from the Siahroud stream (northern Iran) between February and June 2010. The specimens ranged in size from 27 to 103 mm total length and weighed from 0.13 to 8.93 g total weight. The overall sex ratio was unbalanced as females dominated, with 342 females and 226 males being caught (sex ratio 1.5 : 1). Length- weight relationships implied that growth was positively allometric for both sexes. The von Bertalanffy growth function was estimated to be L t = 94.95 (1 - e -0.49(t + 0.34) ) for males and L t = 121.65 (1 - e -0.39(t + 0.43) ) for females. Egg diameter ranged from 0.44 to 1.02 mm, with a mean value of 0.77 mm. Absolute fecundity varied from 212 to 4666 eggs. Fecundity relative to total weight fluctuated from 383 to 268 eggs g -1 . These growth and reproduction traits may be interpreted as species life history capacity and/or adaptation to environmental conditions caused by the southern Caspian climate.