Morphometric differentiation of Clarias gariepinus strains in Nigerian water bodies using multivariate analysis

Abstract

The pattern of morphometric differentiation among selected populations of Clarias gariepinus across Nigerian water bodies and major hatcheries representing different geographic regions (NW, NE, NC, SW, SS and SE) were examined using multivariate tools of Principal Component Analysis (PCA) and Discriminant Function Analysis (DFA). The phenotypic characteristics of C. gariepinus populations which include the traditional and Truss measurement representing about 42 distances on specific landmarks were used. Morphological comparisons clearly revealed morphometric homogeneity between C. gariepinus fish population in River Benue and River Niger and their tributaries as these populations were seen to densely overlap. Remarkably morphological heterogeneity was seen in some population from River Benue and the Dutch exotic strains from a SW hatchery. Another exotic strain from South Africa was not very distinct on the discriminant space, as it was observed to overlap slightly with the R. Benue sourced strain. The present morphometric analysis of C. gariepinus in sites with links to River Niger and River Benue and their tributaries, revealed five considerably distinct populations. These combined data provide a valuable baseline for further investigations on the geographic distribution of this commercially important species as they may have been introduced to these water bodies from a common source.

Keywords: Morphology, landmarks, truss measurement, River Benue, River Niger, Nigeria