Biometry analysis, length-weight relationship and sexual dimorphism of the Spotted Scat, Scatophagus argus (Linnaeus, 1766) (Perciformes: Scatophagidae) from Gulf of Mannar, southeast coast of India

Abstract

A total of 1,659 specimens of spotted scat were collected from commercial landings in Mandapam along Gulf of Mannar for studying biometry, length-weight relationship and sexual dimorphism. Biometry was carried out to analyse the growth rate of body parts in relation to the standard length. Fourteen morphometric characteristics were examined. The study revealed that the fastest growth rate was in depth of the body followed by pre-dorsal and pre-anal length and lowest in the eye diameter. The length-weight relationship was also carried out for 1,141 females ranging in TL from 140 - 340 mm and 518 males in the range of 50 - 117 mm. The equation of W = 0.005373 L2.842 and W = 0.002152 L2.479were derived for male and female respectively. The relationship revealed that the value of exponent ‘’b’’ was considerably below 3, which might be due to the deep, strongly compressed body. Analysis of covariance revealed that there were significant differences (P< 0.01) between sexes. Male and female spotted scat could be differentiated by head shape and colour of body. Females were larger and heavier than males of the same length group.