An overview on the fisheries population of Arabian scad, Trachurus indicus Nekrasov, 1966 (F: Carangidae) caught by two different fishing methods from the Gulf of Suez, Red Sea, Egypt

Trachurus indicus is a semi pelagic species caught by the bottom trawl and purse seine gears adopted in the Gulf of Suez, Red Sea. The objective of this study was to demonstrate and compare the fish size, length frequency, ages and length-atage of T. indicus in the two fishing gears. The average T. indicus catch percentage constituted about 20% of the total trawl catch during the period from Sep. 2010 to Nov. 2011, while it formed about 50% of the total purse seine catch. The lengths and age compositions of T. indicus were varied between sexes in the two gears. Length ranged from 10.0±0.85cm to 26.5±1.82cm in the trawl fishery; however it ranged from 6.5±0.66 to 22.0±1.45 cm in the purse seine fishery. The maximum life span of T. indicus was estimated at 5 and 7 years in purse seine and trawl respectively. The growth parameters were evaluated as K= 0.37/year, L∞ 23.9 cm and K= 0.39/year and L∞ = 22.6 cm for males and females respectively in purse seine gear. While, in the trawl gear K= 0.42/year, L∞ 24.6 cm and K=0.34/year, L∞= 27.9 cm for males and females respectively. Also, the instantaneous total, natural and fishing mortality rates were investigated in the two gears. Results indicated that, T. indicus is exactly different in length composition, age composition and mortality rates in the two fishing gears under study. As T. indicus is the most abundant commercial species in the Gulf, its production was exploited mainly by the two gears and the exploitation rates were approximately the same over 0.7.