Contributions to the biology of penaeid prawns of the south-west coast of India I. Sex ratio and movements

The biology and fishery of Indian Penaeid prawns of commercial importance particularly of the south-west coast, are being studied in detail by the Central Marine Fisheries Research Station and some of the results obtained so far have been already published (Menon 1951, 1953, 1954, 1955 and Panikkar and Menon, 1955). The present contribution deals with the sex ratio at successive stages of life in four species, namely, Metapenceus dobsoni, Pentms indicus, Metapenceus affinis and Parapemeopsis stylifera. Some observations on this aspect in relation to M. dobsoni have been included in the second of the two, papers dealing with its biology (1955). The discovery of the wide disparity in the proportion of the sexes in the third year of life of this species provided the incentive for a more extensive study of the problem in the same species as well as in three other species also