A. Haghi Vayghan - Department of Ecology & Aquatic stocks management, Artemia & Aquaculture Research Institute, Urmia University, P.O. Box: ۵۷۱۷۹-۴۴۵۱۴, Urmia, Iran.
S.A. Hashemi - Iranian Fisheries Science Research Institute, Agricultural Research, Education and Extension Organization (AREEO)
F. Kaymaram - Iranian Fisheries Science Research Institute, Agricultural Research, Education, and Extension Organization (AREEO), Tehran, Iran.

In the present research, the Catch-only method was used to determine the biological reference points (BRPs) of Longtail tuna (LOT) in Iranian southern waters (Persian Gulf and Oman Sea). Depletion-based stock reduction analysis (DBSRA) and Catch maximum sustainable yield (CMSY) models were used to estimate BRPs by applying data from ۱۹۹۷ to ۲۰۱۸.The B/BMSY was calculated as smaller than ۱.۰ in both models, while F/FMSY was mostly higher than ۱.۰, which indicates the overfishing of Longtail tuna in this area. In ۲۰۱۲, the F/FMSY ratio has exceeded over ۱.۰۱ and the B/BMSY ratio with ۲ years delay was declined in ۲۰۱۴. Consequently, the biomass reduction followed in ۲۰۱۶, declined to the below of BMSY and the fishing pressure was not adjusted to combat. In comparison, DBSRA model indicated more cautious than CMSY in BRPs estimation for LOT in Iranian southern waters. Based on BRPs, it is recommended to implement an adjustment of annual harvest (around ۵۵ thousand tons) as the simple (even quick) fisheries management strategies in order to guarantee the sustainable yield of this species in southern waters of Iran. We also recommend that catch-only methods could be treated as a temporary stepping-stone while sufficient data (e.g. size or age composition) is available for more reliable methods to be applied.

Longtail tuna, Biological reference point, Fisheries management, Persian Gulf and Oman Sea