The barbs (Barbus spp.) of Lake Tana: a forgotten species flock?

Abstract

In October-December 1990, the large barbs (Barbus) that contribute more than 35% of the catch in lake Tana (northern Ethiopia) were studied. Previous authors (Riippelll837, Boulenger 1902,1911, Bini 1940 described from 6 to 23 (sub)species for the lake. Banister (1973) lumped all of these into one subspecies: Barbus intermedius intermedius Riippell, 1837. We found that the Lake Tana Barbus could be readily categorized in at least 13 discrete morphotypes, some of which were already distinguished by local fishermen. None of the known descriptions are adequate to distinguish the barbs unambiguously, which is important for monitoring and management of developing fisheries. Intermediates between morphotypes were rare (< 10%). By applying canonical discriminant analysis on a set of 17 morphometric characters (including some directly associated with feeding) our initial morphotype-distinction was confirmed. Also, differences between the morphotypes in distribution, related to depth and substratum were found, as well as differences in intestinal contents, a key to the food-niche. The high number of piscivorous morphotypes (8 out of 13) was striking as piscivory is relatively rare among cyprinids. Piscivory was found to be highly correlated with morphological (feeding related) characters. The presence of discrete morphotypes, that also differ in food-niche and distribution, strongly suggests that several distinct populations exist, that may be (partly or completely) reproductively segregated. Knowledge about these populations, that may represent separate units of fish stock, is of crucial importance for the management of sustainable fisheries and protection of the biodiversity in Lake Tana. It is possible that several species or even a unique cyprinid species flock are present, that urgently need protection.

Growth, biomass, and production of two small barbs (Barbus humilis and B. tanapelagius, Cyprinidae) and their role in the food web of Lake Tana (Ethiopia)

“…Nagelkerke et al, 1994;Sibbing & Nagelkerke, 2001). Surprisingly, eight of these are piscivores (de Graaf et al, 2008).…”

Seasonal variation in primary production of a large high altitude tropical lake (Lake Tana, Ethiopia): effects of nutrient availability and water transparency

“…It is located in northeastern Africa, and is with a surface area of 3,200 km 2 and a catchment's area of 16,500 km 2 the largest lake in Ethiopia. In this Lake 15 large barb species (Labeobarbus) compose a world unique concentration of endemic cyprinid fish (Nagelkerke et al 1994;Nagelkerke and Sibbing 2000). The fish community contains furthermore three endemic diploid species of small barbs (Barbus spp.)…”

Evidence of a Cenozoic Betic–Kabilian Connection Based on Freshwater Fish Phylogeography (Luciobarbus, Cyprinidae)

“…However, this type of approach is difficult due to the high degree of polymorphism shown by species of this genus, in which species flock phenomena have been described (Nagelkerke et al, 1994;Mina et al, 1996;Reig et al, 1998). Recent electrophoretic studies have analyzed genetic variation at the population and species levels, as well as phylogenetic relationships (e.g., Berrebi et al, 1990;El Gharbi, 1993;El Gharbi et al, 1993;Karakousis et al, 1995;Machordom et al, 1995Machordom et al, , 1998Slechtová et al, 1998).…”