Aspects of the biology of grey mullet, Mugil cephalus L., adult populations of a coastal lagoon in Sri Lanka

The biology of grey mullet, Mugil cephalus L., adult populations in a coastal lagoon in Sri Lanka is presented. The percentage of grey mullet catches increased with increasing salinity. The larger fish were found in the deeper areas and the relationship of total length to depth was L = 8.4602e^{0.0058 D} where L = total length and D = depth (cm). The overall female to male ratio was 0.95 : 1.0 and seasonal variation in the sex ratio is considered to be caused by the differential timing in the spawning migrations of the two sexes. Males mature at 34.0 cm and females at 31.5 cm. The main spawning season was between January and May and it is hypothesized that the breeding season is geared to utilize the favourable time period, for growth of fry, in the lagoon. Grey mullet sheds its eggs in batches. Fecundity varied from 0.45 to 4.2 million in fish ranging in length from 32 to 56 cm and in weight from 0.7 to 2.2 kg. Fecundity was significantly correlated to body length and weight and gonad weight.