Age, sex ratio, length-weight relationships and reproductive biology of Mediterranean swordfish, Xiphias gladius L., 1758, in the eastern Mediterranean

Abstract

In this study, a total of 87 swordfish were collected from the Aegean Sea and northern Levantine Sea. The range of the lower jaw fork length was 99.0 to 161.0 cm (mean 15.45 cm) for males and 87.0 to 188.5 cm (mean 26.02 cm) for females. Females were slightly more numerous than males (39 males and 48 females). The estimated sex ratio was calculated as 1.23. The maximum value of gonadsomatic index (GSI) for the males (2.16) and females (10.09) were observed in June and May respectively. High GSI value which were observed in May (10.09) indicated that the female reproductive cycle started depends on the size of the individuals. In the present study, the length-weight relationship was calculated as W = 1x10^-6 L^{3, 4627}, R² = (0.95). The coefficient “b” was close to positive allometric values (b = 3.46). Total of 48 anal spines (25 males and 23 females) were examined. The ages varied from 1 to 7 and the maximum age was determined as 7. Two-year-old fish were dominant (35.4%).

Key words: Swordfish, Xiphias gladius, reproduction biology, sex ratio, length-weight relationship, Eastern Mediterranean.