Browsing by Author "Nakiyende, Herbert"

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    Ecology of the Critcally Endangered Singidia Tilapia (Teleostei: Cichlidae: Oreochromis esculentus) of lake Kayanja, Uganda and its conservaton implicatons
    (Journal of Threatened Taxa, 2020) Olwa, Richard; Nakiyende, Herbert; Muhumuza, Elias
    Singidia Tilapia Oreochromis esculentus is a Critically Endangered native tilapia fish species endemic to lakes Victoria and Kyoga basins of East Africa, however, it disappeared from these main lakes due to overfishing, environmental degradation and predation by the introduced Nile Perch Lates niloticus. Remnant populations of this fish species is now restricted to satellite lakes including Lake Kayanja of the Victoria basin. This study provides updated information about the population abundance, critical habitat, threats and diet of Singidia Tilapia to inform conservation decisions to revive its populations in the wild. Fish data collection and mapping of nursery and breeding habitats of Singidia Tilapia on Lake Kayanja was conducted between February 2016 and October 2017. In all the areas mapped and sampled, Singidia Tilapia (with a size range of 11–27 cm TL) was the most abundant (43%) relative to exotic Nile Tilapia Oreochromis niloticus (21%) and Redbelly Tilapia Coptodon zillii (36%). The emergence of introduced (exotic) tilapias like Nile Tilapia recorded in this study could be attributed to cage fish farming being carried out in this Lake. The diet of Oreochromis esculentus consisted mainly of detritus (60.8 %), plant materials (27.7%) and blue-green algae (5.5%). Destruction of critical habitats and presence of introduced fish species were noted as the major threats to this fish and its habitats. The generated information could contribute to guiding stakeholders to undertake appropriate actions to conserve this threatened fish species and its habitats.
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    Future success and ways forward for scientific approaches on the African Great Lakes
    (Journal of Great Lakes Research, 2023) Lawrence, Ted J.; Achieng, Alfred O.; Chavula, Geoffrey; Haambiya, Lloyd Haninga; Iteba, Jacob; Kayanda, Robert; Kaunda, Emmanuel; Migenim Z. Ajode; Muvundja, Fabrice A.; Nakiyende, Herbert; Nyamweya, Chrisphine; Obiero, Kevin; Pierre, Denis Plisnier; Harris, Phiri; Claver, Sibomana; Stephanie, Smith
    The seven African Great Lakes are some of the most critical freshwater, large-lake systems in the world, providing essential services, food, drinking water, and other livelihood support to over 62 million people. Like most freshwater systems around the world, these lakes are strained by anthropogenic stressors, leading to degradation of these biologically important, and human-dependent resources. Despite their importance, these lakes suffer from insufficient research approaches which are short-term, disparate, and unharmonized. Further, a lack of monitoring, data and information exchange, education and training, and gender balance in research, all lead to insufficient knowledge on which to better manage and protect these lakes. While past efforts have resulted in some knowledge accumulation, there is a need for new approaches to understanding and managing these lakes: bottom-up, harmonized, and long-term processes. This paper, and those within this special section of the Journal of Great Lakes Research, highlight new, highly collaborative efforts of freshwater experts representing each riparian country of each African Great Lake through formal advisory groups. These papers are the result of harmonized efforts and collegial agreements as to what issues need to be addressed foremost, written by those on the ground. While each lake has specific, prioritized lists of issues, five overarching issues must be addressed to achieve success on these lakes: providing agency and coordination of African freshwater scientists; increase long-term monitoring; strengthen education and training of existing and future experts; enhance information and data exchange; and ensure stronger gender balance in science and leadership positions.
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    Saving the Endangered Native Victoria Tilapia, Oreochromis Variabilis Boulenger (1906), in Upper Victoria Nile
    (Uganda Journal of Agricultural Sciences, 2020) Bassa, Samuel; Ogello, Erick Ochieng; Musinguzi, Laban; Sekiranda, Stephen; Nakiyende, Herbert
    This study investigated the catch estimates, mortality, growth, food and feeding habits, and water parameters of Oreochromis variabilis in Upper Victoria Nile (UVN) from 2008 to 2019. Catch rates ranged 0.32±0.08 to 3.42±1.13 kg, boat-1 , day-1 with the length-weight relationship indicating Isometric growth. Growth parameters obtained were L∞=36.75, K=0.44 yr-1 , t0=-0.4540, tmax=6.4years, ØL=2.774, ØW=-0.301. Total mortality (Z) was 1.74yr-1, natural mortality (M) =0.95yr-1 using riverine surface temperature (RST) of 26oC giving a fishing mortality F of 0.79 yr-1 and exploitation ratio (E) of 0.4504 showing that growth parameters concurs with annual estimates and yield (F=6.589; P±=0.05). Catch estimates correlated with water parameters that indicated a significant difference. Mortality parameters showed that the fishery could be experiencing exploitation pressure. Although growth rates revealed that the fish is a long-lived species, if managed properly, its population could recover. Therefore, culturing the species and restocking in rivers and lakes in which this specie was not observed in the East African region are recommended.