Research Article: Length-based fishery status of yellowfin tuna (Thunnus albacares Bonnaterre, 1788) in the northern waters of the Oman Sea

In the present study, population characteristics of Thunnus albacares were evaluated by sampling at five fish landing sites in the northern Oman Sea including Beris, Ramin, Pozm, Konarak and Jask from March 2017 to March 2018. The biometric analysis was performed on more than twenty-six thousand fish. Population dynamic parameters were calculated including infinite length (L∞=171 cm), growth coefficient (K=0.54 (yr-1)), growth performance index (Фchr('39')=4.19), natural mortality (M= 0.71(yr-1)), fishing mortality (F=1.57 (yr-1)), total mortality (Z=2.28±0.19 (yr-1)), exploitation coefficient (E=0.68 (yr-1)) and initial condition parameter (-0.18 yr-1). Relative production per recruitment, relative biomass per recruitment and exploitation rate of this species were Ychr('39')/ Rp = 0.04, Bchr('39')/ Rp=0.23(yr-1) and U=0.62 (yr-1), respectively. The Pobj value is <1, Popt and Pmega>0, and F/Fmsy>1. The results indicated that regarding length frequencies of this species in the northern part of the Oman Sea, yellowfin tuna stock has good conditions, but overfishing of this species is happening, now. Therefore, specific measures should be taken to reduce catch and fishing effort.