A comparative study on the fish species composition, diversity and catch rates among the fisheries reserves on the Zambezi and Kwando rivers, Zambezi region
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Date
2025
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University of Namibia
Abstract
The Zambezi and Kwando Rivers in northeastern Namibia support vital floodplain
fisheries that provide food, income, and seasonal employment for many local
communities. However, increasing pressure from overfishing, habitat degradation,
and climate change has highlighted the need to establish fisheries reserves to
promote sustainable resource use. This baseline study evaluated fish assemblages,
specifically species composition, diversity, and catch per unit effort (CPUE); across
five fisheries reserves located along the Zambezi River (Sitwela, Kabweza, and
Makangala) and the Kwando River (Luhingi and Qhuqhumupa). Gillnet surveys
using both experimental and monofilament gillnets were conducted between 13
November and 13 December 2021. A total of 3,360 individual fish, representing 32
species, were captured. On the Zambezi River, Makangala had the highest species
richness with 24 species, followed by Sitwela with 21 species, and Kabweza with 20.
On the Kwando River, Luhingi recorded 17 species, while Qhuqhumupa had 12.
There was no statistically significant difference in species diversity among the
reserves (H(4)=8.268, p=0.082). However, overall CPUE (by weight) varied
significantly between sites (H(4)=46.621, p<0.001), with Luhingi showing the highest
CPUE (0.704±0.78 kg/set) and Kabweza the lowest (0.209±0.14 kg/set). Significant
differences in individual CPUE were observed for two commercially important
species: Clarias gariepinus(H(4)=26.783, p<0.001) and Clarias ngamensis
(H(4)=17.967, p=0.001), while no significant variation was found for Serranochromis
macrocephalus (H(3)=0.260, p=0.967). Similarly, mean fish sizes for C. gariepinus
(H(4)= 25.850, p<0.001) and C. ngamensis (H(4)=14.660, p=0.005) differed
significantly across sites, whereas no difference was noted for S. macrocephalus
(H(3)=0.779, p=0.885). Regression analysis showed that temperature had no effect on
fish catch rates. However, reserve size explained 14% of the variation in catch rates.
These spatial differences in catch rates for key commercial species may be
influenced by factors such as the degree of protection, age, and size of the reserves.
In particular, higher CPUEs in the Kwando River reserves may be attributed to
stronger protection measures and longstanding conservation awareness compared to
the more recently established reserves along the Zambezi River. These findings
underscore the need for tailored, site-specific management strategies to ensure the
sustainability of fish populations across all five newly established fisheries reserves
in the region
Description
A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Science in Environmental Science
Keywords
Fisheries Reserves, Co-management, Species diversity, Fisheries management, Baseline, Assessment, Namibia, University of Namibia