Mak Researchers develop Innovative Integrated Wetlands-bivalve system to Mitigate Effects of Pollution in Aquaculture farms in the Lake Victoria Basin

The Project team with the participants during the workshop at Colline Hotel Mukono on 26th June 2024

By Hasifa Kabejja & Dr Robinson Odong


The fisheries sub-sector in Uganda is crucial, supporting over 5 million livelihoods and providing essential protein for up to 17 million people, with an average consumption of 10 kg per capita. Uganda’s population is projected to double in the next 27 years, prompting the National Development Plan III to aim for a significant increase in fish production, with aquaculture expected to contribute 1 million MT by 2030. The Fisheries and Aquaculture Act 2022 emphasizes adherence to National Environmental Management principles to achieve sustainable production systems.

However, as aquaculture grows, the sector faces environmental challenges due to increased intensive production and on-farm waste, including nutrients from feed, uneaten feed, poor quality feeds, pseudofeces, escaped farmed fish, and residual chemicals. These pollutants pose risks such as habitat quality deterioration, biodiversity loss, eutrophication of waterways, and the emergence of drug-resistant pathogens.

The Principal, CoNAS, Makerere University, Prof. Winston Tumps Ireeta officially opened the workshop

Mitigating the effects of environmental pollution from aquaculture

Through a Project titled: Mitigating the Effects of Environmental Pollution from aquaculture on freshwater resources in Lake Victoria Basin (MEEP), researchers from Makerere University in collaboration with the National Environment Management Authority (NEMA) set out to assess the effects of aquaculture facilities and practices on Lake Victoria, its catchment rivers and wetlands. The team led by Dr Ronald Semyalo from the Department of Zoology, Entomology and Fisheries Sciences (ZEFS) at Makerere University subsequently examined the effectiveness of innovative technologies, such as integrated wetland-bivalve systems, in mitigating these impacts. They also reviewed the application of national environment and aquaculture regulations in controlling environmental pollution. The study surveyed fish farms in three districts of Buikwe, Jinja, and Mukono within the Victoria Water Management Zone. Other project team members were: Dr Jerome Lugumira from NEMA, Dr Robinson Odong and Mr. Drake Ssempijja from ZEFS, Makerere University, and Ms. Ritah Namisango, Senior Public Relations Officer at Makerere. The Project was supported by the Government of Uganda through the Makerere University Research and Innovations Fund (MakRIF).

Some of the participants at the workhop at Colline Hotel Mukono

During their engagement with different stakeholders in the fishing industry including the fish farmers from Jinja, Buikwe and Mukono, as well as experts from the Directorate of Water Resources at the Ministry of Water and Environment, NEMA, and the Directorate of Aquaculture Development at MAAF, the research team established that only 138 out of 380 registered fish farms were active, with 45.6% of the farms in Jinja, 35.5% in Mukono; and 18.8% in Buikwe. Overall, over 60% of the farms were inactive posing serious environmental threats.  

The PI, Dr Ronald Semyalo presenting the project findings to stakeholders

Dissemination of the research findings

On 26th June 2024, the project team held a workshop at Colline Hotel Mukono to disseminate the research finding to stakeholders who included fish farmers from Buikwe, Jinja and Mukono, District Fisheries Officers, as well as representatives from NEMA and MAAIF. In the presentations, the team highlighted the environmental impacts of aquaculture practices and the possibility of innovatively using nature-based, environmentally friendly innovations as a mitigation measure. The presentations covered farm characteristics, water and feed management practices, water quality assessments and waste management methods. The participants engaged in discussion on the implications of the results and shared their experiences and challenges in managing aquaculture operations.

Dr Semyalo disseminating the research findings
Mr. Geoffrey Dheyongera, Principal Fisheries Officer at MAAIF delivered a presentation on the state of capture fisheries and aquaculture in Uganda

Key findings as disseminated by the PI

Out of the 380 farms, 119 were assessed. Below are the key findings;

  1. Environmental Impact Assessment: It was established that 81% of the farmers had not conducted Environmental Impact Assessments (EIAs) and Environmental audits. This, the researchers noted was one of the major causes of abandoned farms. 
  2. Farm Characteristics: The majority of farms used earthen ponds (66.9%) and were semi-intensive (63.6%), relying on manufactured feed and pond fertilization. Intensive farms (30.5%) exclusively used manufactured feeds, while extensive farms (4.2%) relied solely on pond fertilization.
  3. Fish Species: Nile tilapia was the top choice (96.1%) for monoculture farms, while tilapia and catfish were preferred for polyculture systems (46.9%). Intensive farms predominantly farmed Nile tilapia.
  4. Demographics: Most respondents were male (90.7%), with a median age of 35 years. The largest age group was 31 to 59 years (43.2%).
  5. Fish diseases: The research revealed a number of diseases affecting aquaculture including: lesions/wounds on the belly and cysts on the scales, skin lesions and cysts on the belly, popping eyes and white substance on fins, open skin wounds, open wounds on the head, skin lesions – greyish, swollen eyes, whitish and black patches on the skin on the pelvic fin, wounds on the head.
  6. Water Use: Fish farms primarily relied on spring water and lake water. Other sources, such as streams, wells, and rivers, were also utilized. In most cases, the water source was shared with the community. Only a small percentage of respondents acknowledged any known disease outbreaks on their farms. There was a strong association between the district in which the farm was located and the water source used. Majority of those using lake water were in Jinja District, while most of those using spring water were in Mukono District. Additionally, there was a significant association between the fish species cultured and the water source used. 
  7. Feed Management: A significant proportion of the farms heavily relied on factory-made feeds. These feeds were often used in combination with farm feed materials, such as maize bran, potato vines, yam leaves, and kitchen waste. A smaller number of farmers exclusively relied on farm-made feeds, while an even smaller percentage solely relied on pond fertilization. Manufactured feeds were used in various forms: powder and floating pellets, powder, crumble, and floating pellets, powder only, floating pellets only, and sinking pellets. The most prevalent method of feed delivery was feeding by response, while some farms also practiced feeding by ration.
  8. Waste Management: The findings indicated a concerning lack of treatment for aquaculture effluent, with majority of respondents (69%) releasing it directly into natural streams or wetlands. This highlights the need for improved environmental management practices.  Common waste sources included faecal matter and dead fish. Most farms incinerated or buried solid waste. 
  9. Water Quality: Measurements at the representative visited farms showed compliance with FAO optimal conditions for fish farms. The physicochemical parameters of the farms visited were in line with FAO optimal conditions for fish farms.
  10. Prevailing Regulatory System: A comprehensive gap analysis was conducted to supplement the findings from the survey. It aimed to identify weaknesses and areas for improvement in current policies and regulations governing aquaculture. It also evaluated the effectiveness of existing measures in addressing environmental pollution, waste management, and sustainable water use. This exercise provided a foundation for developing more robust and effective regulatory frameworks that support sustainable aquaculture practices, protect water resources, and enhance the overall environmental health of the Lake Victoria basin.
Stakeholders at the MEEP dissemination workshop

Project output

***Innovative Integrated wetlands-bivalves system was developed to mitigate the impact of pollution emanating from aquaculture on the environment

Effluent from poor aquaculture practices may contain uneaten feed residues and associated components, such as suspended solids, nutrient nitrogen and phosphorus and organic materials. If discharged without any form of treatment, such effluent contributes to excessive nutrient enrichment of water bodies, a phenomenon referred to as eutrophication. Eutrophic waters have diminished ecological value, for example are low in oxygen level and can lead to fish kills. Wetland plants, such as duckweeds can aid in cleansing of aquaculture effluent of excess pollutants, through various mechanisms. For example, the plant roots adsorb suspended solids, besides offering conducive attachment surfaces for beneficial microorganisms which perform various nutrient recycling roles. The plants also uptake excess nutrients, hence reducing their levels in water. Bivalves (Molluscs) are filter feeders, hence uptake and cleanse water of detrital or solid materials, hence augmenting the roles of the plants. The integration of wetlands-bivalves system offer synergistic roles in aquaculture effluent treatment. The plants and bivalves used in the treatment can in turn be removed and used for other beneficial purposes.

Dr Jerome Lugumira from NEMA delivered a presentation on the policies regulating the sector and the gaps

Presentation on policy gaps

During the dissemination workshop, Dr Jerome Lugumira, the Natural Resources Manager, Soils and Land Use at NEMA sensitized participants on the National Environment Act, 2019 with special emphasis on policy regulations for the aquaculture sector. He emphasized the need to acquire an EIA certificate before engaging in aquaculture. Highlighting the gaps in policy, Dr Lugumira noted that Schedule 4 of the National Environment Act, 2019 does not sufficiently guide the Fisheries sector; while the Physical Planning Act, 2010 is biased towards physical development planning, and the Water Act, 1997 provides for a waste discharge permit but no consideration of the extent of wastes discharged from fish farms of varying size and intensity is provided.

Dr Lugumira sensitizing participants on the policies

He further noted that the National Environment (Wetlands, Riverbanks and Lakeshores Management) Regulations, 2000 do not guide on areas where aquaculture best fits, indicating that the application of the 25% wetland area beyond which one needs approval is vague.

Additionally, he explained that the National Environment (Waste Management) Regulations, 2020 refer to fish waste generally and not whether it means waste from fish or all waste from fish farms, such as off-cuts, unwanted materials, and that the National Environment (Standards for Discharge of Effluent into Water or Land) Regulations, 2020 consider effluent discharge and not that released in-situ and that disposed directly into water via cages and into soil via land-based systems.

Left-Right- Dr Susan Luyiga, Dr Peter Akoll, and Ms. Ritah Namisango at the dissemination workshop

Dr Lugumira called for the review of the National Environment (Wetlands, Riverbanks and Lakeshores Management) Regulations, 2000, by requiring the mandated Lead Agency (WMD) to issue approvals for access to wetlands, and appending guidance on wetlands and lake areas where aquaculture is suitable. He suggested that submissions seeking approval from NEMA should have all required approvals from MAAIF, WMD and DLGs. “The assessment process should be supported by a technical officer skilled in fisheries sciences and not generalists,” he noted.

The Guest of Honour, Mr. Alio Andrew briefed participants on proper aquaculture management practices and called on Ugandas to invest in the fisheries sector

Overview on the state of capture fisheries and aquaculture in Uganda

Sharing an overview on the state of capture fisheries and aquaculture in Uganda, Mr. Geoffrey Dheyongera, Principal Fisheries Officer at MAAIF, noted that the global decline/stagnation in capture fisheries stocks had increased demand for fish, calling for a boost in fish production through stock enhancement in water bodies and promotion of aquaculture. “There is need for huge investment in aquaculture. The Aquaculture Policy targets 1 million MT from aquaculture through establishment of aquaparks with intensive management activities.”

One of the technologies developed by the project team to support the mitigation of the effects of aquaculture on the environment

Key concerns raised by the farmers

During the focused group discussions, participants highlighted a number of factors undermining the growth of the aquaculture sector. These include;

  1. Ignorance about the laws/policy guidelines
  2. Low skills and lack of exposure in aquaculture management
  3. Low numbers of technical staff to guide the farmers
  4. Inexperienced technical staff
  5. Cheating by fish seed producers
  6. Expensive and poor quality feeds
  7. Fluctuating prices of fish
  8. Competition with capture fisheries/negative attitude towards farmed fish
  9. Increased degradation of the environment which affects water quality
  10. High interest rates on loans
  11. Farmers fear for exorbitant taxes
Participants in group discussions on the factors undermining aquaculture

Proposals for improvement

  1. Government should recruit technical staff to assist farmers
  2. Thorough training of extension staff
  3. Encourage value addition to farmed fish
  4. Integrate climate smart interventions in aquaculture
  5. Policies regulating the sector should be popularized
  6. Undertake periodical review of the existing policies
  7. Encourage multi-stakeholder involvement in the implementation of policies
  8. Invest in research responsive to fish and aquaculture sector needs
  9. Monitor quality of fish feeds to satisfy farmers’ needs and environmental safety
  10. Private hatchery operators must be supported by the responsible sector agencies to ensure quality seed. Likewise, fish seed must come from certified hatcheries.
  11. Inspection of farms should be strengthened
  12. Train farmers on proper aquaculture management practices
  13. Farmers should work in groups to reduce production costs, negotiate better prices for their products, access credit facilities and maximize profits
Group discussions on aquaculture

Remarks by the Guest of Honour, Mukono District CAO, and the Principal, CoNAS

In his remarks, the Guest of Honour, also Assistant Commissioner Aquaculture Management at MAAIF, Mr. Alio Andrew, guided the farmers on proper aquaculture practices, and encouraged Ugandans to invest in the fish sector. “The demand for fish has increased. Aquaculture remains a viable option,” he noted. He also raised the need to support private hatchery operators to produce quality seed, emphasizing that fish seed should only be bought from certified hatcheries. He highlighted the significance of biosecurity in aquaculture, and the need to collect appropriate data on the sector.

The CAO Mukono District called for intensified training of farmers in aquaculture management practices. She advised the farmers to work in groups if they are to make reasonable profits.

The Principal, College of Natural Sciences (CoNAS), Makerere University, Prof. Winston Tumps Ireeta, acknowledged the involvement of the community in research, and appreciated the fish farmers for actively participating in the project activities. He expressed gratitude to the Government of Uganda for the continued support towards research at Makerere University. Besides other initiatives geared towards improving research at Makerere, the Government is supporting over 700 research projects at Makerere through the Research and Innovations Fund. He also appreciated MAAIF and NEMA for the technical guidance extended towards the project.

The Representative of the CAO Mukono District delivering her remarks
A participant presenting the views of his group on the factors undermining aquaculture
The Secretariat at the dissemination workshop. On the left is Ms. Catherine Nannyonga, the Project Administrator

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