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The present study was conducted in six stations of Sistan and baluchestan province east coast by underwater counting method in two seasons (before and after Monson) and depths of less than 5 meters and depths of 5 to 10 meters, in 2019 and 2020. A total of eight hundred and two sea cucumbers (624 males, 178 females) of different biometrics as well as three hundred and one sea cucumbers (71 females, 71 males and the rest immature) were described. The mean length and weight of females and males of Holothuria leucospilota species were 361±105, 366±96 mm and 438 ±150, 411±140 g, respectively. The length mean (± standard deviation) of the total sea cucumber samples was 295± 89 in the range of 185-150 mm and the weight average (± standard deviation) was 254 ±150 in the range of 3500-75 g. Spawning time for this species in the province resulted with smaller peaks (December and January) with an average sexual maturity index of 8±2 and an average water surface temperature of 25± 1; Also, a larger peak (June and July) with an average sexual maturity index of 18 ± 4 and a mean surface water temperature of 30 ± 1. Maturity length of female was 220 mm, male was 246 mm and the mean (confidence interval) for all samples was 222 mm(172-280). Mean infinite length, annual growth coefficient, growth performance index (Phi) , natural mortality, fishing mortality, total mortality and expoliation coefficient for all samples were obtained 50 cm, ,0.5 (yr-1), 3.11, 0.97 (yr-1), 0.47 (yr-1), 1.44 (yr-1) and 0.33, respectively. The average number of sea cucumber estimated for the after season of Monson and the before season of Monson was 142 (170-114) and 120 (134-106) in the eastern area of Sistan and Baluchestan province, respectively. Also, the range of peresent biomass was between 518-420 tons and biomass harvestable in the two seasons was between 59-77 tons. Multi-layered artificial neural network(MANN) and redundancy analysis showed that this species sea cucumber were phosphate-related changes.Key Words: Sea cucumbers, Stock assessment, Chabahar beaches.
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