Population dynamics of the Spanish mackerel (Scomberomorus commerson) in coastal waters of Oman Sea

Length composition data of narrow-barred Spanish mackerel, Scomberomorus commerson (Lacepede ۱۸۰۰), landed between April ۲۰۰۲ to March ۲۰۰۴, were monthly used to estimate the growth, mortality and exploitation parameters of the stock. Maximum fork length and weight were ۱۷۰ cm and ۳۸ kg, respectively. Nonlinear least square fitting provided a complete set of von Bertalanffy growth estimates: L¥=۱۷۸ cm (FL); K=۰.۲۸ and to= -۰.۳۶ years. The estimated value of total mortality based on length converted catch curve using these growth parameters is Z=۰.۹۵ year-I. Natural mortality based on growth parameters and mean environmental temperature (T=۲۶.۵°C) is M=۰.۳۶ year-۱. Furthermore, the annual instantaneous fishing mortality rate of ۰.۵۹ year-I was by far in excess of the precautionary target (Fopt=۰.۱۸ year-۱) and limit (Flimit=۰.۲۴ year-۱) biological reference points, indicating that the resource is heavily over-exploited and the management of this species should be implanted rapidly if they are to remain sustainable.