Turkish Journal of Fisheries and Aquatic Sciences
2007, Vol 7, Num, 2 (Pages: 115-121)
Age, Growth and Mortality Rate of the Narrow-Barred Spanish Mackerel (Scomberomerus commerson Lacepède, 1800) in Coastal Waters of Iran from Length Frequency Data
2 Iranian Fisheries Research Organization, IFRO, Tehran, Iran
3 Dept. of Marine Biology. Faculty of Marine Science, Tarbiat Modarres University,Tehran (TMU), Iran
4 Fisheries Dept,. Faculty of Marine Science, Tarbiat Modarres University (TMU), Tehran, Iran
5 Persian Gulf and Oman Sea Ecological Research Institute, Bandar Abbas, Iran Viewed : 4278 - Downloaded : 4180 Monthly data of length composition for narrow-barred Spanish mackerel, Scomberomorus commerson (Lacepède), landed between April 2003 to March 2005 along the Persian Gulf and Oman Sea were used to estimate the growth, mortality and exploitation parameters of the stock. Maximum fork length and weight were 132 cm and 18.4 kg respectively. Nonlinear least square fitting provided a complete set of von Bertalanffy growth estimates: L∞=140 cm fork length; K=0.42 and t0= -0.26 years. The estimated value of total mortality based on length converted catch curve using these growth parameters is Z=1.47 year-1. Natural mortality based on growth parameters and mean environmental temperature (T=26.5ºC) is M=0.49 year-1. Furthermore, the annual instantaneous fishing mortality rate of 0.98 year-1 was by far in excess of the precautionary target (Fopt=0.49 year-1) and limit (Flimit=0.65 year-1) biological reference points, indicating that the resource was heavily over-exploited, and that management of this species should have been implanted rapidly if they were to remain sustainable. Keywords : Scomberomorus commerson, Growth, Mortality, Overexploitation, Iran