STUDIES ON THE REPRODUCTIVE BIOLOGY OF THE BROWN PRAWN METAPENAEUS MONOCEROS (FABRICIUS, 1798) ALONG THE KAKINADA COAST

Abstract

Five ovarian maturation stages are recognised in Metapenaeus monoceros. Males and females attain size at first maturity at 96 and 116 mm total length (TL) respectively. Each female spawns at least four times in its life time with an interval of about 2 months between successive spawnings. After attaining maturity, males are sexually active throughout their life. Spwaning season is prolonged extending from January to October. The following linear relationships are obtained between fecvmdity and total length/ total weight/ovary weight. Fecundity (in thousands) = -507.1369 + 4.9593 x total length Fecundity (in thousands) = -25.4832 + 9.7134 x total weight Fecundity (in thousands) = -18.3825 + 96.6413 x ovary weight Ovary weight is a better index of fecundity than either total length or total weight. Fecundity varies from 51,684 ova in female of 113 mm TL to 402,378 ova in a female of 181 mm TL. The ratios of males to females vary from 1 : 3.21 to 1 : 0.29 in different months. These wide variations in the sex ratio are found to be associated with the sex-wise segregation in the fishing grounds. Annual sex ratio in the population is significantly different at P = 0.01 level from the usual 1:1 ratio.