The determination of some biological characteristics of horse mackerel (Trachurus trachurus L., 1758) caught in Samsun Bay

The present research was carried out during the period of November 2004 to March 2005 in order to determine some population parameters of the horse mackerel (Trachurus trachurus L., 1758) in the Samsun Bay (Turkey) which is one of the most important fishing areas in the Black Sea. A total of 1290 individuals (591 female, 647 male) were investigated according to age, length, weight and sex composition, the relationship of length-weight, condition factor, Von Bertalanffy growth formula and mortality rates. The female-male ratio was 1:1.1. The specimens belonged to 0-V age groups and the age-group II was the dominant one (37.60%). In the research, the length-weight relationship was found for general, male and female as W=0.0063 L super(3.0931) (r=0.98), W=0.0056 L super(3.1378) (r=0.96), W=0.0055 L super(3.1423) (r=0.97) and the Von Bertalanffy growth formula was found for general, male and female as Lt=26.74(1-e super(-0.138 (t+2.824))), Lt=26.88(1-e super(-0.132 (t+3.075))), Lt= 26.59(1-e super(-0.131 (t+3.229))), respectively. The growth of horse mackerel was determined as positive allometric. It was determined that the average condition value of population was 0.6299 plus or minus 0.00151 0.5628 plus or minus 0.002 for females, 0.5519 plus or minus 0.0018 for males. Total (Z), natural (M) and fishing (F) mortalities were Z=1.26 year super(-1), M=0.27 year super(-1) and F=0.99 year super(-1), respectively. The exploitation ratio E=0.79 indicates that the population is being heavily exploited.