Morphological Divergence During Growth in the Large Barbs (Barbus Spp.) of Lake Tana, Ethiopia

Abstract

Recently the large Lake Tana barbs (genus Barbus) were categorized into at least 13 distinct morphotypes based on large differences in general morphology, distribution and feeding habits. They are probably different populations and may even constitute a unique cyprinid species flock. This study demonstrates that 11 of the 14 morphotypes (as an additional morphotype 'Shorthead' is identified in this paper) can already be distinguished by their general external features at fork lengths of less than 12 cm. These distinctions were verified by statistical analysis of morphometric data. The distinction of the morphotypes in small specimens supports the hypothesis that several distinct Barbus species exist in Lake Tana. Knowledge of the population structure and species composition is very important for the reconstruction of the evolutionary history and mechanisms of this unique fish community. Moreover, in order to protect the biodiversity of the lake, it is important that the fisheries in the lake only increase on a sustainable basis and a detailed knowledge of the fish community structure is vital to achieve this goal.