Natugonza Vianny- National Fisheries Resources Research Institute, Uganda, Jinja
Natugonza Vianny
- National Fisheries Resources Research Institute, Uganda, Jinja
About
43
Publications
15,448
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
587
Citations
Introduction
Current institution
National Fisheries Resources Research Institute, Uganda, Jinja
Publications
Publications (43)
Adequate knowledge is essential for responsible inland fisheries. However, many inland fisheries lack monitoring, and therefore, decision‐making for fisheries management is not reliable. In this paper, we used data from surveys and literature to estimate the life‐history and growth parameters of 16 exploited fish stocks in the Ugandan part of Lake...
Poor and unreliable knowledge of the status of freshwater fisheries limits their inclusion in governance processes, thereby impeding effective management measures. This threatens the livelihoods of people, particularly in developing countries. Improved knowledge is required to draw the attention of policymakers and stimulate effective management me...
Assessing the conservation status of species according to their extinction risk is a major step in conservation planning. To date, most of the assessments have been conducted at a global scale; yet, most conservation efforts are conducted at the national or local scale. Also, the global assessments often do not fit individual countries whose biodiv...
Freshwater fishes are the second most threatened group of vertebrates after amphibians. In most developing countries, the conservation of freshwater fishes is largely hampered by limited information and data. The Red List assessments by the International Union for Conservation of Nature (IUCN) provide a benchmark for monitoring and mitigating speci...
Effective conservation requires reliable data and information on the status of biodiversity. The conservation of freshwater biodiversity lags behind terrestrial and marine biodiversity because data and information limitations are greatest in freshwater ecosystems. Given that freshwater ecosystems are inhabited by disproportionately more species tha...
Most small-scale inland fisheries in the Global South prohibit fishing gear with smaller meshes than is
legally permitted. Nonetheless, in most instances, this is not strictly enforced. But starting in 2017,
Uganda and Tanzania ramped up enforcement on Lake Victoria. We used time series hydro-acoustic data
to determine whether the strict enforcemen...
Freshwater fishes are the second most threatened group of vertebrates after amphibians. In most developing countries, the conservation of freshwater fishes is largely hampered by limited information and data. The International Union for Conservation of Nature (IUCN) Red List assessments provide a benchmark for conservation and development planning,...
Freshwater fishes are the second most threatened group of vertebrates after amphibians. In most developing countries, the conservation of freshwater fishes is largely hampered by limited information and data. The Red List assessments by the International Union for Conservation of Nature (IUCN) provide a benchmark for conservation and planning, but...
Inland fisheries support the livelihoods of millions of people in riparian communities worldwide but are influenced by increasing climate variability and change. Freshwater fishing societies are among the most vulnerable to climate change given their dependence on highly threatened aquatic resources. As climate change intensifies, building adaptive...
Balanced harvest (BH) refers to applying moderate fishing pressure across a broad range of species, trophic levels (TL), stocks, or sizes in an ecosystem in proportion to productivity (gross production per biomass unit) or production (total cumulated biomass over a given period) instead of exerting pressure on particular taxa or sizes. Both modelli...
Funding biodiversity conservation strategies are usually minimal, thus prioritizing habitats at high risk should be conducted. We developed and tested a conservation priority index (CPI) that ranks habitats to aid in prioritizing them for conservation. We tested the index using 1897 fish species from 273 African inland lakes and 34 countries. In th...
Lakes Victoria, Kyoga, and Nabugabo (“the Lake Victoria region”) are remarkable for hosting one of the largest assemblages of cichlid fishes among the African inland lakes. Here, we review the role and severity of anthropogenic and environmental stressors on the cichlid communities in the Lake Victoria region to understand the mechanisms leading to...
The unknown status of inland fish stocks hinders their sustainable management. Therefore, increasing stock status information is important for sustainable inland fisheries. Fisheries reference points were estimated for five exploited fish species (11 stocks) in the Lake Edward system, East Africa, which is one of the most productive inland water sy...
Sedimentation of water bodies affects water quality and biotic communities of aquatic ecosystems. Understanding the causes and origin of sediments is crucial for planning watershed management activities and safeguarding aquatic biodiversity and critical ecosystem services. Rwanda, as a hilly country, experiences increased sedimentation due to unsus...
Freshwater ecosystems occupy <1% of the Earth’s total surface area but provide an array of ecosystem services. However, these ecosystems are threatened by multiple stressors, including overexploitation, infrastructure developments, habitat alteration, and alien species introductions. The magnitude of these threats varies in different water bodies,...
We determined fisheries management reference points for three major fish stocks in Lake Victoria (Nile tilapia, Nile perch and Dagaa) for Uganda and the whole lake. The aim was to ascertain stock status and define reasonable objectives and targets for rebuilding to sustainable levels. Dagaa was found to be healthy in Uganda and the whole lake but t...
Lake Victoria biophysical and geochemical status has changed dramatically within an unprecedentedly short time scale driven by human actions. These actions can be broadly classified as escalated fisheries exploitation, biomanipulation (characterized by species introduction) and catchment processes. A chronology of these activities since 1901 to pre...
Most small scale inland fisheries worldwide are open access, and fishing provides the only source of employment and livelihood for the riparian communities. Management of these fisheries requires information on trade-offs between fish production, profits from fishing, employment, and conservation objectives. We use the non-linear optimization proce...
Biomass of the schooling fish Rastrineobola argentea (dagaa) is presently estimated in Lake Victoria by acoustic survey following the simple “rule” that dagaa is the source of most echo energy returned from the top third of the water column. Dagaa have, however, been caught in the bottom two-thirds, and other species occur towards the surface: a mo...
Biomass of the schooling fish Rastrineobola argentea (dagaa) is presently estimated in Lake Victoria by acoustic survey following the simple “rule” that dagaa is the source of most echo energy returned from the top third of the water column. Dagaa have, however, been caught in the bottom two-thirds, and other species occur towards the surface: a mo...
Long-term time series data are not available for many of the African Great Lakes. This precludes fitting ecosystem model parameters to time series data, and we do not know how reliable non-fitted models are compared to fitted ones in terms of predicting consequences of alternative management strategies. To investigate this, we generate a historical...
Cage aquaculture is expanding on African inland waters and has potential to close the fish supply deficit
in the region and provide other social benefits such as employment and income. However, if not appropriately
guided and regulated, cage aquaculture could become unsustainable, causing conflicts with other
water uses, environmental degradation a...
Cage aquaculture is expanding on African inland waters and has potential to close the fish supply deficit in the region and provide other social benefits such as employment and income. However, if not appropriately guided and regulated, cage aquaculture could become unsustainable, causing conflicts with other water uses, environmental degradation a...
Ecosystem simulation models are valuable quantitative decision tools for supporting ecosystem-based fisheries management. However, the application of ecosystem models in fisheries management is still
undermined by the lack of simple procedures to test the effect of model uncertainty on policy outcomes. The use of multiple ecosystem models is viewed...
Ecosystem simulation models are valuable tools for strengthening and promoting ecosystem-based fisheries management (EBFM). However, utility of these models in practical fisheries management is often undermined by lack of simple means to test the effect of uncertainty on model outputs. Recently, the use of multiple ecosystem models has been recomme...
This dataset presents fish species occurrence records for Uganda mobilized from unpublished archives. The archives accumulated from fish biodiversity surveys that scientists at the National Fisheries Resources Research Institute (NaFIRRI)conducted at different periods in most of the aquatic ecosystems of Uganda.
This dataset presents fish species occurrence records for Uganda mobilized from unpublished archives. The archives accumulated from fish biodiversity surveys that scientists at the National Fisheries Resources Research Institute (NaFIRRI) conducted at different periods between 1996 and 2017 in most of the aquatic ecosystems of Uganda.
The small pelagic cyprinid, Rastrineobola argentea (Pellegrin), commonly known as dagaa, accounted for 60% of the total fish biomass and 40% of the commercial catches in Lake Victoria in 2015. However, some aspects of the biology of species (from which management interventions are based) have changed since 1970s; and yet harvest regulations have re...
The Lake Victoria Basin is home to the most extensive wetlands in Eastern Africa and these wetlands support remarkably high levels of floral biodiversity. Freshwater plants have a diverse range of uses, with variations in use depending on the plant part and life stage. Medicinal use of plants is very common in rural communities, as there is often n...
Climate change disproportionately affects marginalized groups, especially women. To guide the integration of gender roles in interventions to improve adaptation, we examined gender roles among fishers on Lake Wamala, Uganda, which has been increasingly affected by climate change. We found lower participation of women than men in preharvest and post...
Climate variability and change, which intensified since 1970s, are threatening natural resources and livelihoods in Sub-Saharan Africa where people depend on climate sensitive natural resources, such as agriculture and fisheries, but have limited capacity to adapt. Increasing human and institutional capacity to address threats posed by climate chan...
Ecosystem-based fishery management (EBFM) is the best option where other fishery management objectives have failed. This makes EBFM important for the African inland lakes and fisheries resources that are among the most threatened in the world despite existing management interventions. Ecosystem modeling provides information that guides EBFM, and, t...
Climate variability and change that have been intensifying since the 1970s are accompanied by changes in hydrology and water balance of inland aquatic systems. These changes, however, have not been well documented with regard to small and shallow aquatic systems that are more vulnerable. Changes in temperature, rainfall and wind speed around Lakes...
Inland fisheries are important for nutrition, employment, and income, but climate variability and change are adding to other stressors, such as overexploitation, pollution, habitat degradation, and invasive species, to threaten their productivity as well as livelihoods of fisheries-dependent communities. Understanding the whole socio-ecological sys...
Inland fisheries are important for nutrition, employment, and income, but climate variability and change are adding to other stressors, such as overexploitation, pollution, habitat degradation, and invasive species, to threaten their productivity as well as livelihoods of fisheries-dependent communities. Understanding the whole socio-ecological sys...
Fisheries resources support livelihoods of fishing communities but are threatened by over-exploitation, habitat degradation, pollution, invasive species and climate change. Unlike the other threats, climate change has received limited consideration and reducing its risks requires appropriate adaptation strategies. This study used quantitative and q...
Changes in the catches of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758), in Lake Wamala (Uganda) have been observed since its introduction. The factors contributing to these changes, however, are not well understood. This study examined changes in species composition, size structure, size at first maturity, length–weight relationship and con...
The Kyoga lake system, which is c. 4 m deep, originally had a diverse fish fauna, extensive macrophytes and wetlands. Most (82%) of its water comes from Lake Victoria, is controlled through three dams and has a short residence time of c. 3 months. Physical and chemical factors, plankton productivity and composition vary across the lake from east to...
Questions
Question (1)
I am reviewing literature about ecosystem changes in Lake Victoria (East Africa). I know, from Odum's 24 indices of ecosystem development and maturity, that values of primary production to respiration ratio <1 suggest eutrophication, while values >1 suggest an immature system. However, in one of the papers, where authors were describing the trophic characteristics of Mwanza gulf (Lake Victoria), using ecopath, they reported a primary production to respiration ratio >500. Question 1: Is this value realistic? Question 2: Does this mean that Mwanza gulf is not eutrophic? Question 3: How am I supposed to interpret this value based on principles of ecosytem development?
