Feeding ecology of the African tigerfish Hydrocynus vittatus castelnau, 1861 in the floodplains of the Kavango river, Namibia
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Date
2023
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University of Namibia
Abstract
The feeding ecology of the African tigerfish Hydrocynus vittatus was investigated in the floodplains of the Kavango River, Namibia. A total of 275 samples of tigerfish were caught, using a seine and an experimental multifilament gillnet, during the annual flooding period between February and May 2020. The result of the study shows a significant ontogenetic dietary shift (P < 0.05) between size classes of tigerfish. The study also find a significant different (P < 0.05) in the diet composition of different size classes of tigerfish, where small size class tigerfish (20 mm -149 mm) fed predominately on aquatic macro invertebrates, which contributed by percentage number 94.5 % (N%), feeding mainly prey on the group of Corixidae 42.5%, Notonectidae 25.5% and Letophilebiidae 18.2%. Medium size class tigerfish (150 mm – 190 mm) fed on both portions of fish (Enteromius spp) and aquatic macro invertebrates (Trichoptera and Libellulidae)and the large size class tigerfish (200 mm - 585 mm) were predominately piscivorous (68.2 % N), feeding mainly on Cichlidae 34.9% and M. altisambesi 15.9 %. Overall, the results of the study show that tigerfish did not consume prey larger than 150 mm in total length (TL), and the predator - prey length ratio was approximately 23%. The study findings show that tigerfish on the Kamutjonga floodplains feed predominately on aquatic macro invertebrates when in the early stages of life and are piscivorous in the adult stage life. The study results provide important information in understanding the dietary requirement of tigerfish in the Kamutjonga floodplains. Such information is important in conservation measure of tigerfish. Henceforth, the study recommended multi-species modeling studies based on predator-prey interactions, in order to better understand, resource use and partitioning among species on the Kamutjonga floodplain.
Description
A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Science Biodiversity Management
Keywords
Feeding ecology, African tigerfish, Hydrocynus vittatus