Current status of Liza ramada (Risso, 1810) (Mugilidae) caught by trammel net (Ballah) at El-Gamil region, Manzala Lake, Egypt

Abstract

Liza ramada, the target species caught by trammel net (Ballah) at El-Gamil region, north of Lake Manzala, is studied to estimate the life history parameters by using length–frequency data of 842 specimens. The life span was estimated as 4 years. It exhibited a negative allometric growth (b=2.94). The von Bertalanffy growth parameters were L∞= 30.45cm, K= 0.48 yr−1 and t0 =-0.339 yr−1 with a derived growth performance index of O′ =2.6 .The mean annual instantaneous total, natural and fishing mortality coefficients were 1.47, 0.71and 0.76/year, respectively. The exploitation rate was estimated as 0.52. The probability of capture ensured that 50 percent (Lc) of the fish caught was estimated at length 12.18 cm which is 31.2% lower than the length at first sexual maturity (17.7 cm) and lower by 40.1% than the estimated Lopt value (20.4 cm). This result reflects the smaller mesh sizes of the inner layer of nets used by fishermen. Therefore an urgent recommendation should be applied to prevent the illegal fishing gears, increase the mesh sizes especially for the inner layer of trammel net used as well as improving the quality of water discharged into the lake to increase the yield per recruit of Liza ramada, protect fish stocks and to secure a profitable fisheries and optimum catch efficiency for the future.