Abstract

The diets of three fish species of commercial importance in Lake Baringo, Protopterus aethiopicus, Clarias gariepinus and Oreochromis niloticus, were determined using frequency of occurrence and volumetric methods between April 2008 and March 2010. Seine and gill nets were used to catch a total of 430 fish specimens. The diet of P. aethiopicus was 94.3% molluscs with a frequency of occurrence of 98.6% of stomachs with food. Adult C. gariepinus fed mainly on fish with 75% of the stomachs with food containing fish remains and mean of 49.2% contribution by volume. C. gariepinus also fed on zooplankton, especially the cladoceran Daphnia barbata. The food items in the stomachs ofO. niloticus consisted mainly of algae, detritus and zooplankton. Algae was consumed by O. niloticus of all length classes in proportions ranging from 26.5 to 88.1%. The importance of zooplankton as food for O. niloticus decreased with size of fish. The study reveals the importance of zooplankton as food for O. niloticus and C. gariepinus in Lake Baringo. There is need to rehabilitate the catchment of Lake Baringo so as to improve the water quality thus improve productivity. Key words: Diet, Omnivorous, Algae, zooplankton, food web.

Highlights

  • Lake Baringo lies in a closed drainage basin of the Kenyan East African Rift Valley system at an altitude of 965 m above sea level with a surface area of approximately 130 km2 and a mean depth of 3.5 m

  • This study investigated the diet and the trophic inter-relationships of P. aethiopicus, C. gariepinus and O. niloticus in Lake Baringo

  • The diet of P. aethiopicus was dominated by molluscs with a mean composition of 94.3% (Table 2) with a frequency of occurrence of 98.6% of stomachs with food

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Summary

Introduction

Lake Baringo lies in a closed drainage basin of the Kenyan East African Rift Valley system at an altitude of 965 m above sea level with a surface area of approximately 130 km and a mean depth of 3.5 m. The lake’s water quality has deteriorated in the recent past mainly due to sedimentation from its catchment arising from poor agricultural practices, deforestion and overgrazing. These have led to a decline in fish catches. The fish community of Lake Baringo comprises seven species These include Aplocheliches sp, Barbus intermedius australis, B. lineomaculatus, Clarias gariepinus, Labeo cylindricus, Oreochromis niloticus baringoensis and Protopterus aethiopicus (Britton et al, 2006). Baringoensis exceeded 600 t in the 1960s but this decreased to mean annual catches of below 12 t in 2006 despite a prolonged period of fishery closure (Britton et al, 2006) Annual catches of O. n. baringoensis exceeded 600 t in the 1960s but this decreased to mean annual catches of below 12 t in 2006 despite a prolonged period of fishery closure (Britton et al, 2006)

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