Comparative study on reproductive ‎biology of Caucasian dwarf goby ‎Knipowitschia caucasica (Berg, 1916)‎‏ ‏in ‎Gomishn Wetland and Gorgan Bay

To study reproductive characteristics of Caucasian dwarf goby (K. caucasica), a total of 149 samples were caught in the Gorgan bay and 192 inthe Gomishanwetlandusing beach seine during a period from February 2014 to May 2016.Thereproductive characteristics including sex ratio, gonadal development index, and absolute fecundity, relative fecundity were calculated.Samples of Gorgan bay ranged from 8.07 to 39.41 mm TL and 0.01 to 0.84 g total weight, while the samples caught in Gomishan wetland had total lengthlength between 15.48 to 44.78 mm and in the total weight between 0.05 to 1.10g.The highest condition factor in the Gorgan bay for both sexes was observed in February and March, and in the Gomishan wetland for in January and April. In the both study areas, the highest average GSIof females was observed in March and of malesin April. Minimum, maximum and average ofabsolute fecundity were 79.80, 888 and 387,37in the Gorgan bay respectively, and the relative fecundity were 152.58, 2733.54 and 797.11 respectively. While absolute fecundities’ minimum, maximum and averagewere 136.96,1002.22 and 482.94 and those of relative fecundity 243.70,2326.53 and 870.32. Ova diameter ranged between 0.24 to 0.84 mm with a mean value of 0.52 mm, and in the Gomishan wetland mean of the diameter was 0.50 mm ranging from 0.26 to 0.85 mm. Analysis of GSI revealed that the species spawns once per year in a short period, and has different eggs during this period.