The spatial, temporal and vertical fish species composition of the kamutjonga floodplain, Kavango river, Namibia
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Date
2023
Authors
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Journal ISSN
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Publisher
University of Namibia
Abstract
The present study investigated the variations in fish species composition on a floodplain
during a flood pulse on the floodplain along Kavango River, Namibia. Specifically, the
study aimed at comparing the species composition, the catch per unit effort, and the body
length of two selected species (Pseudocrenilabrus philander and Tilapia sparrmanii)
across periods during the flood, across depth intervals and sites on the floodplain. Further,
the study also aimed at determining any correlation between the catch per unit effort and
the physio-chemical parameters of the water. A throw trap net was used to sample six (6)
sites along the peripheries of the Kamutjonga floodplain during its inundated period (20
February 2020 to 09 June 2020), with each site subdivided into three depth intervals – 0-
29 cm, 30-59 cm and 60-99 cm. Three flooding periods (early, middle and late) were
identified during the flood pulse. A total of 48 throws were cast at each site per flooding
period, with each depth interval sampled 16 times per site. A total of 30 species were
recorded on the floodplain, with the highest number of species (17) recorded during the
early flooding period, in the deepest section sampled (60 – 99 cm) (21 species) and at site
2 (20 species). Cichlids dominated the floodplain, with Oreochromis andersonii and
Pseudocrenilabrus philander being the most important species during the early and late
flooding period, respectively. Few but large specimens were on the floodplain during
early flooding, whilst a lot of small (by weight) specimens were during the late flooding
periods. More specimens, yet large (by weight) were found on the shallow section (0 – 29
cm) of the floodplain. The findings uphold the significance of the peripheries of newly
inundated areas, which are documented to serve as breeding, nursery and forage grounds
for most riverine species. A large proportion (83%) of individuals such as those of P.
philander were above sexual maturity during the early flooding period, which coincided
with the highest number of small-sized specimens during the late flooding period – further
hinting at the use of the floodplain as a breeding ground
Description
A thesis submitted in fulfilment of the requirements for the degree of master of science in biological sciences
Keywords
Floodplain, Fisheries, Kavango River, Kamutjonga, Throw-trap net, Fish species composition, Spatio-temporal, Namibia