Population dynamic of the oriental river prawn (Macrobrachium nipponense) from Golestan Dam Lake – Golestan Province

Oriental shrimp is conexotis species that widely distributed in northern Iran. This study was conducted to determine population dynamic characteristics of this species based on Its specimen in Golestan dam lake from February to September 2016. Sex ration was unbalanced  in favorite of females (1 : 1.88). Total length and weight ranged from 16.06 to 85.01 mm and 0.04 to 6.75 gr respectively. There was significant difference in relative abundance and mean weight among months. Mean length and weight for males (mean TL = 42.26 mm, mean W = 1.12 gr) were larger than that of females (mean TL = 41.15 mm, mean W = 0.99 gr). Growth pattern was positive allometric for both sexes (bfemale = 3.16, bmale = 3.15). VanBertalanffy growth equation was Lt = 87.5(1-e-0.85(t+0.14)) for females and Lt = 87.5(1-e-0.9(t+0.132)) for males. Natural mortality was calculated as 2.09 for females and 2.17 for males indicating high mortality rate for both sexes.