Stock status Investigating of longtail tuna (Thunnus tonggol Bleeker, 1851) based on limited data approach in Iranian southern waters (Persian Gulf and Oman Sea)

The purpose of this study to develop a framework for investigating the catch trend and estimation of optimized catch limit of the T. tonggol stock by collecting catch data in the Iranian southern waters.  In this research, the information of twenty-five years of catch of this species was prepared and with use of data limited approach and R software, estimation of optimal catch was made. The average catch (Ct) for this study period was 44609 tons (95% confidence interval 38882-53936 tons) and the average catch (R = 0.74, P < 0.05) increased significantly during the study period. Average (maximum-minimum) of carrying capacity (K), current biomass (B), maximum sustainable yield (MSY), biomass of maximum sustainable yield (BMSY) based on Catch-MSY (CMSY) model, Optimized catch-only model (OCOM) model and Zhou-Boosted regression tree models(Zhou-BRT) model was estimated and the mean reference points not show significant difference by statistical tests (P>0.05). This research shows that the annual harvest of Longtail tuna species has reached its maximum amount and no increase in fishing is suggested for this species.