Multivariate analysis of morphological traits of sexually mature Sarotherodon galilaeus (Linnaeus, 1758) in Ogun State Coastal Estuary, Nigeria

Abstract

Morphological variation in sexually matured Sarotherodon galilaeus was assessed from commercial fishermen operating Iken brushpark – fish aggregating device in Ogun State coastal estuary, Nigeria. Fifteen morphometric features and nine meristic characters were analysed using both univariate and multivariate analyses between the sexes of the population. Univariate analysis showed higher mean values in most of the morphometric and meristic counts of the female population than the males, but significant differences (p<0.05) were recorded in total length, standard length, head length, pectoral ray and gill raker of the first arch. Two and four Principal components were extracted for morphometric and meristic characters with 78.702% and 63.428% total variances respectively. Sexual differences occurred in morphometric characters such as, eye diameter, body weight, head width, length of dorsal base and length of pectoral fin while meristic counts showed overlapping in spinous dorsal fin rays, pectoral fin rays, scales along lateral line, scales above lateral line and gill rakers on the first arch. Canonical Discriminant function revealed the heterogeneity of total length, pectoral fin rays and gill rakers on the first arch in both sexes and these features could be used for the identification of the fish. This study revealed that multivariate statistical tools are effective means of analysing data for proper taxonomy, conservation and management of fish stocks.

Keywords: Morphological traits, Multivariate analysis, Sarotherodon galilaeus, brushpark, meristic characters