Reproductive cycle and changes in condition of the horse mackerel (Trachurus trachurus L.) from the Adriatic Sea

Abstract

      Annual cyclical changes in gonad weight, gonosomatic index and condition factor in male and female horse mackerel (Trachurus trachurus L.) from the Adriatic Sea were studied. This species is a late winter through early spring spawner. Maturation lasts from December to May and spawning occurs during March to early June, the peak in May. Testes initially increase in weight faster and earlier than the ovaries and they maintain a greater weight for a longer period. However, at the most advanced gonadal development ovarian weight exceeds testicular weight. Changes in condition were closely linked to the reproductive cycle, condition factor being high and constant for both males and females during the prespawn­ing periods. It was lowest after spawning and highest at the end of the recovering period.