Morphometric and sexual characteristics ofMacrobrachium rosenbergii(De Man, 1879) from the Nyatoh River, Malaysia

Abstract This study was conducted to evaluate the morphological variation of Macrobrachium rosenbergii (De Man, 1879) from the Nyatoh River, Terengganu state, Malaysia. Three hundred and thirty-five samples of M. rosenbergii comprising 41.5% males and 58.5% females were collected from August 2019 to October 2020. The bulk of the sample collection had small claws (69.1%), whereas those with orange and blue claws constituted 19.1% and 11.8%, respectively. The result obtained from the analysis of nine sets of morphometric data for both sexes showed univariate morphometric similarities and wide overlap in principal component analysis (PCA) without separation into unique clusters. Comparison by claw-type showed significant variation in the univariate analysis of the morphometric parameters measured in the following order: blue claw > orange claw > small claw. PCA did not cluster the prawns into different groups, hence multivariate analysis of morphometric parameters cannot be used to distinguish the prawn by claw type should the appendages be lost. Comparisons of the length-weight relationship data and condition factor suggest that the Terengganu River prawn population had a positive allometric growth pattern and were in good condition. The Pearson’s correlation analysis also showed a largely positive relationship between the morphometric data collected (with a few exceptions in the different morphotypes). The morphological measurements could not therefore be used to discriminate the sex and claw-type of freshwater prawn M. rosenbergii in the Nyatoh River.