Aspects of the biology of Liza abu (Mugilidae) in the Tigris River (Turkey)

Abstract

Sex distribution, growth in length and weight, relative condition index, attainment of first maturity age, and fecundity of Liza abu were examined in the Tigris River, South-eastern Anatolia. This species migrates towards upstream the Tigris River at a period extending from August to late February. The age of 480 specimens (263 females and 217 males) ranged between 1+ and 4+. The observed sex ratio was 1.21 female: 1 male in the studied samples. Allometric growth patterns was proved from the length-weight relationships. The female had high L infinity (204.27 mm), but low K (0.304531) value whereas the Lm (195.77 mm) for male were lower, but the K (0.383129) value was higher. It was seen that relative condition index values from August and September were higher than those recorded at other times of the year. Spawning do not occur at this time in this area. According to development of gonad, male and female become sexually mature at the first year of their life-span. The smallest mature female was 117 mm in fork length and 17 g in total weight, while male was 115 mm in fork length and 14 g in total weight. The number of oocytes ranged from 12,175 to 56,400. Fecundity was significantly correlated with fish length, fish weight and gonad weight.