Morphometric and Meristic Variations Between Populations of White-Spotted Rabbit Fish, Siganus sutor (VALENCIENNES, 1835) from the Kenyan Coast

Abstract

Morphometric and meristic variations were used to investigate the population structure of the White-spotted rabbit fish, Siganus sutor (Valenciennes, 1835) in order to determine what degree of isolation may result in notably phenotypic and genetic differentiation among its populations. Samples of the species were collected along the Kenyan coast from Malindi, Mombasa and Shimoni. A total of 31 morphometric measurements were taken from each of the 98 fish collected. 6 meristic characters were also counted in the specimens. All morphometric analysis was log-transformed and linear regression models used to estimate allometric coefficients of growth. The morphometric measurements were standardized to mean total length using an allometric formula and multivariate statistics used to analyse both morphometric and meristic characters. Principal component analysis revealed good discrimination between populations of the White-spotted rabbit fish from Shimoni, Mombasa and Malindi. Shimoni and Mombasa populations were different from one another while those from Malindi shared characteristics with both the Shimoni and Mombasa populations. Observed morphometric differences came from the ventral fin lengths and caudal peduncle widths for the Shimoni populations and mouth width, post-orbital length, head diameter and lower jaw width for Mombasa populations. From the results, discrimination observed can be attributed to diversity of environmental conditions, habitat characteristics and possibly food and feeding habits. Overall, morphometric characters were more useful than meristics in differentiating the three populations.