Morphological Characterization and Relationship between Morphometric Parameters and Standard Length Barbus altianalis (Boulenger, 1904) Populations in Lake Victoria Drainage Basin, Kenya

Aim: To provide data on external morphology of Barbus altianalis from four major rivers in Lake Victoria watershed, determine whether there are significant morphometric differences between sub-populations from the rivers of the catchment area examined and to determine relationship between morphometric parameters and standard length (SL).

Methods and Results: Morphometric analysis was carried out in the study. Based on 21 morphometric characters, Barbus altianalis populations from four Lake Victoria catchment rivers Nzoia, Yala, Nyando and Sondu-Miriu were morphologically characterised based on 21 morphometric parameters. Principal Component Analysis (PCA) showed separation of Rivers Yala from Nzoia, Nyando, and Sondu-Miriu populations. Factor loadings established that 11 characters were morphologically informative. PCA1 accounted for 43.25% of the variation while PCA2 accounted for 19.44% of the variation. Mann-Whitney U Test (α=0.05) indicated lack of significanct difference in morphological characteristics between Sondu-Miriu and Nyando, but significant intra-specific morphological difference between all the other pairs of rivers. All external parameters except 4 showed positive relationship with standard length (SL). Our results suggests presence of intra-specific morphometric variation between the four populations and corroborate findings based on mitochondrial DNA analysis.

Conclusion: Morphological characterization reveal intra specific variation in Barbus altianalis in the Lake Victoria catchment and suggests the existence of river specific morphs, a possible adaptation to changes in the catchment. This could also provide evidence of long term existence of migratory as well as riverine sedentary populations of the species within Lake Victoria basin (LVB).