LENGTH-WEIGHT RELATIONSHIP IN SOME COMMON PRAWNS AND LOBSTERS (MACRURA, NATANTIA AND REPTANTIA) FROM THE

nization of the United Nations (F.A.O.) and was a part of the F.A.O. Indian Ocean Programme to render scientific assistance to developing countries. A study of commercial crustaceans was an essential part of the research. Decapod crustaceans (mainly prawns and spiny lobsters) are of great importance for marine fisheries in the Indian Ocean countries (Longhurst, 1970). Due to their value, the crustaceans are extensively studied in many countries (e.g., India, Australia, South Africa). Nevertheless, length-weight relationships have been established only for few decapods inhabiting the western Indian Ocean. The present paper deals with the results of the biometrical analysis of common and abundant decapods from trawl catches of the R/V "Professor Mesyatsev". MATERIAL AND METHODS A study was made of the following relationships: length of carapace-total length and vice versa; carapace length-weight, and total length-weight. The list of species studied, the number of species measured and weighed, areas and periods of the collection, are given below. More detailed data on length and weight frequency distributions of the specimens analysed, on positions of haul, and records of the species are presented in the Report on the results of studies conducted from 1975 to 1976 on board the R/V "Professor Mesyatsev", which was submitted to F.A.O. Carapace length of prawns and of Metanephrops andamanicus was measured with dividers from the posterior orbital edge to the middorsal posterior edge of the carapace. Values of the carapace length were determined by putting the dividers to a ruler with an accuracy of 0.1 mm, estimated by the naked eye. The carapace lengths of spiny and scyllarid lobsters were measured from the anterior point of the medial part of the carapace to the posterior middorsal edge