Samples of common Porgy Lethrinus nebulosus were collected monthly from catches of pair trawlers which operated in the north western shelf of Australia from August 1985 to July 1986. From the study of maturity factor, ova diameter frequency and fecundity, the results are summarized as follows; (1) The spawning season is a prolonged one and spawning takes place sometime during – September- February, (2) The minimum size of fish maturity is estimated to be 25 cm. (3) The relationship between fecundity (Y) and fork length (X cm) is found to be Y= 0,0114 x 4,9713.