The Determination of Growth Rate and the Biology of Reproduction in Lethrinus nebulosus in the North-west of Persian Gulf (Khuzestan Province)

Lethrinus nebulosus, which belongs to the Lethrinidae family, is widely distributed along the coasts of Iran. Determining the maturity index is essential in studies of biology, fishery management and aquaculture. In the present study, monthly sampling was conducted on northwestern coasts of the Persian Gulf in Khuzestan from July, 2014 to June, 2015. After biometry and sex determination during monthly sampling, gonadosomatic and hepatosomatic indices, length at 50% maturity, monthly sex ratio and absolute and relative fecundity were calculated for this fish. The gonadosomatic index started increasing from February on and its peak was recorded in April (1.7993). A single peak in gonadosomatic graph indicates one spawning a year. Maximum changes in hepatosomatic index were observed among males in March (0.7449) and among females in April (0.7812).  The length of 50 percent of female adults amounted to 37.2 cm. Absolute fecundity and relative fecundity were calculated as 312415 and 8.24 respectively. The females outnumbered the males in most months of the year. The sex ratio of females to males was 1.99 to 1. This fish reaches maturity in shorter length in the middle coasts of the Persian Gulf than in the eastern and western coasts.