در سواحل ايراني درياي خزر در سال 1380-1379 )ABRAMIS BRAMA ORIENTALIS( پويايي جمعيت ماهي سيم

Population dynamics of Caspian sea bream (Abramis hrama orientalis ) in Iranian coast of the Caspian sea in 2000 - 2001

Bream (Ahramis brama orientalis) is one of the most commercial valuable fish species of the Caspian sea . Total catch of this species was 17 tons in 2000 - 2001 fishing season , which constitute 0.10 % of the all commercial catch of fish species in Iranian coastal water . The mean fork length , weight and age of this species was 21.7+ 3.3 cm , 191 +99.9 gr and 2.72+ 0.91 year ( X + S.D ) repectively . Length - Weight relationship was expressed as W = 0.2312 L^290( R^2=83.34 % , r = 0.91 , N = 160 ) . Length growth parameters of bream based on Von Bertalanffys can be written as : L = 45 [ 1 - exp 01=, +2.76 1 ] The instantaneous rate of total (Z) , Natural (M) and fishing (F) mortality coefficients were 0.92 year ʹ , 0.28 year -ʹ and 0.64 year .ʹ respectively .The exploitation ratio (E) was calculated as 0.7 . Based on cohort analysis , the biomass of this species was calculated as 46.362 tones and according of this amount of biomass , the MSY was estimated as 14.99 tones which is less than the catch of this species .