Morphological Variation of Ten Tilapia guineensis Populations in Selected Rivers in Nigerian coastal waters

Abstract

A morphological study was carried out on Tilapia guineensis, a fish species of considerable dietary importance commonly found in Nigerian coastal waters. Principal component analysis (PCA) revealed two principal components (PC-1 and PC-11) that accounted for 90.3% of observed variation in morphometric attributes; 58.1% and 58.8% in meristics and truss network system respectively. When compared to other locations, fish in Iwoama had the highest mean weight of 0.29+0.006kg with a mean total length of 0.24+0.002m (p<0.05). Truss network data showed that Brass location had the highest mean length of 0.149+0.001m. Among the thirteen morphometric variables considered, pre-anal length (PAL) and standard length were the most correlated (r = 0.96; p<0.01) while dorsal fin count (DFC) and anal fin count (AFC) were the most correlated (0.37; p<0.01) among the meristic variables. Cluster analysis revealed three clusters for meristic variables and two clusters for morphometric and truss network variables respectively. These findings could be attributed to gene flow between widely distributed sub-populations of T. guineensis. However, this fish still possess sufficient variability for possible genetic improvement through breeding.