Research Article: Length-based fishery status of frigate tuna (Auxis thazard) and bullet tuna (A. rochei) in the northern Oman Sea

In the present study, the population characteristics of Auxis thazard and A. rochei were evaluated by sampling at three fish landing sites in the Oman Sea including Beris, Pozm, and Konarak from March ۲۰۲۰ to March ۲۰۲۳. The biometric analysis was performed on ۲۴۰۰ fish specimens. Growth and mortality indices were calculated, including infinite length (L∞=۶۱ and ۴۵ cm), growth coefficient (K=۰.۴۰ and ۰.۴۶ (yr-۱)), growth performance index (Ф=۳.۱۸ and ۲.۹۳), natural mortality (M=۰.۷۷ and ۰.۶۸(yr-۱)), fishing mortality (F=۰.۲۵ and ۰.۱۰ (yr-۱)), total mortality (Z=۱.۰۲±۰.۰۹ and ۰.۷۸±۰.۰۹ (yr-۱)), and exploitation coefficient (E=۰.۲۵ and ۰.۱۳ (yr-۱)), as well as t۰ (-۰.۳۳ and -۰.۳۲ yr-۱). Relative production per recruitment, relative biomass per recruitment, and exploitation rate of this species were Y / Rp = ۰.۰۴, B/Rp=۰.۲۳(yr-۱), and U=۰.۲ and ۰.۰۹ (yr-۱), respectively. The present study showed that the Frigate tuna (FRT) and Bullet tuna (BLT) had desirable stock conditions, and therefore, specific measures should not be taken to reduce catch and fishing efforts. The ratio of spawning potential based on length (LBSPR) of A. thazard and A. rochei was ۰.۳۹ (۰.۳۵-۰.۴۴) and ۰.۶۶ (۰.۵۹-۰.۷۷), respectively. The present study (ratio of LBSPR index and the value of fishing, total mortality and exploitation coefficient) showed that the Frigate tuna and Bullet tuna stock have not reached overfished status. The insights garnered from this research are poised to aid in the management and enduring exploitation of the fish stocks. The findings of this study can assist in the management and sustainable harvest of these tuna species.

کلیدواژه ها:

Frigate tuna ، Bullet tuna ، Population dynamics ، Growth