SPECIFIC IDENTIFICATION AND ASSESSMENT OF DISTRIBUTION AND ABUNDANCE OF EARLY PENAEID SHRIMP LARVAE IN THE GULF OF CARPENTARIA, AUSTRALIA

¹ Division of Fisheries Research, CSIRO Marine Laboratories, P. O. Box 120, Cleveland, Queensland 4163, Australia

Methods for obtaining eggs and rearing larvae of penaeid shrimp at sea, in remote areas, were developed and used to build a comprehensive larval reference collection for taxonomic purposes. Because of the large amount of morphological variation within species and character overlap between species, a multivariate numerical identification technique, discriminant analysis, was tested using larvae of the four species of Penaeus: p. esculentus; P. latisulcatus; P. merguiensis; and P. semisulcatus, in our reference collection. The overall accuracy of the technique is high (> 85%) and can be increased by narrowing the range of natural morphological variation considered, at the expense of decreasing the number of larvae positively identified. Application of the technique to the first zoeal larvae in our plankton collections from the Gulf of Carpentaria, Australia, shows discrete, discontinuous larval distributions which delimit the spawning activity of the four species to a degree not possible by sampling and histological examination of the adult shrimp.