Lake Tanganyika is a vital lifeline for Burundi’s 13 million citizens. Stretching nearly 673 kilometres, it is the longest freshwater lake in the world and the second deepest.
Shared by Burundi, the Democratic Republic of Congo, Tanzania, and Zambia, it supports millions of people with fish, water, and transport. One prized local species is Mukeke (Lates stappersii), a commercially important fish widely consumed across the region.
But the lake is under pressure. Pollution, overfishing, and illegal fishing methods have drastically reduced fish stocks, especially Mukeke. Meanwhile, plastic waste and climate-induced changes are degrading water quality and threatening aquatic life.
On the road from Bujumbura to Rumonge Province, a passenger attributes the decline in fish populations to rapid population growth. Others on the bus disagree, sparking a brief debate.
This exchange reflects a broader discomfort across the region: while many factors contribute to environmental degradation, the impact of fast-growing populations on natural resources is often under-discussed.
Yet, the Nile Basin is experiencing significant demographic changes. According to the Nile Basin Socio-Economic Outlook 2050, the population of the 11 Nile Basin countries is projected to nearly double from 556 million in 2020 to 1.044 billion by 2050.
In countries like Burundi, the Democratic Republic of Congo, and Uganda, the population is expected to more than double during this period. This rapid growth intensifies pressures on fisheries and ecosystems, underscoring the need for integrated resource management (NBI).
Rumonge Province in southern Burundi, about 75 kilometres from Bujumbura, is known for its abundant Mukeke. The province has long been a hub for artisanal fishing. But today, the landing site is quiet. Few people are around. Garbage and sediment line the lake’s edge, emitting a sharp smell. Boats are pulled ashore.
Among the fishers is 55-year-old Daniel Rurihose, who has spent his life on the lake. He remembers when fish were plentiful and families could live comfortably. “We could catch large Mukeke just a few metres from the shore,” he recalls. “Now, it’s no longer the same.”
The problem, he says, is not only the falling catch but also the rising costs. A bucket of fish that once cost 2,000 Burundian Francs (BIF) – around USD 0.65 – now goes for 10,000 to 20,000 BIF (USD 3.25 to 6.50) – and for much smaller fish. “Sometimes I earn just BIF 15,000 or BIF 20,000 a day (USD 4.90 to 6.50),” says Rurihose. “In the past, it could be over BIF 100,000 (USD 32.50).”
Pollution is a growing problem across the Lake Tanganyika basin. Waste from households, transport, and industry – especially in towns like Bujumbura, Kigoma, Uvira, and Rumonge – flows untreated into the lake. Experts warn that the most dangerous pollutants include hydrocarbons, pesticides, and heavy metals from paints and tanneries (NORCE Research).
Gaspard Ntakimazi, an environmental scientist specialising in hydrobiology and fisheries, says these pollutants are especially harmful to species that reproduce in shallow coastal waters. “Their eggs and larvae die, while juveniles and adults flee,” he explains.
Fisherman Rurihose agrees: “Leftover oil from palm production is dumped into pits that eventually drain into the lake.”
Climate change compounds the problem. Heavy rainfall has increased sedimentation and reduced water clarity, disrupting photosynthesis and oxygen levels. “When ph or temperature passes certain thresholds, the water becomes toxic for fish,” says Rémy-Marie Nkurunziza, an environmental chemist at the University of Burundi. “Fish die or migrate.” (IWA Publishing)
In Burundi, three fish species make up most of the annual catch: Mukeke (Lates stappersii), Ndagala (Stolothrissa tanganyikae), and Sangala (Lates mariae). The country’s fisheries law distinguishes between artisanal and traditional fishing, and sets strict rules on gear and seasons. But enforcement is weak.
Many fishers now use gillnets with mesh sizes below 7.6 centimetres – too small to avoid catching juvenile fish. Others use mosquito nets or rope lines, methods that damage fish stocks. “People now use mosquito nets to catch baby fish. When the babies die, the stock declines,” Rurihose says.
Ntakimazi confirms that large Mukeke are now rare in Burundi’s waters. “They are caught in gillnets in the central and southern parts of the lake, especially near Kalemie. Only a few reach southern Burundi.”
Plastic waste is another problem. Floating plastic blocks sunlight, disrupting oxygen production, while decaying plastics reduce oxygen levels through bacterial activity. “Some fish die from lack of oxygen or ingesting plastic,” says Nkurunziza.
He warns that plastic waste has accumulated in Burundi over the years, and a significant portion ends up in Lake Tanganyika, especially during heavy rains that flush debris into the lake from stormwater drains.
Water transparency is one indicator of lake health. While earlier observations mention a decline from 270cm in 2016 to 200cm in 2022, site-specific data from 2021 and 2022 show variation: in Kajaga, transparency rose from 191 to 211 cm; in Rumonge, from 162 to 177 cm (IWA Publishing).
While the trend is inconsistent, experts agree that sedimentation and pollution remain serious concerns.
Burundi once operated industrial fishing through Greek-owned trawlers, but since 2005, only artisanal and traditional fishing remain. Artisanal fishing now accounts for over 80% of national production.
Still, the catch is falling. Compared to 2016, reported national fish production dropped 23% by 2019. Unofficial reports suggest an export decline from BIF 348.8 million (approx. USD 113,500) in 2015 to BIF 3.5 million (approx. USD 1,140) in 2019.
While these figures could not be independently verified, FAO data confirms that Burundi has long had minimal fish exports, often below 10 metric tonnes per year (FAO).
The impact is felt widely. Fish buyer Estelline Dushime, 26, says she often returns home empty-handed. “Mukeke is rare and expensive,” says Dushime. “You spend your capital and get nothing.”
Odette Karerwa, head of the fisheries office in the Ministry of Environment, acknowledges the challenges. “We have limited resources to monitor fishing,” says Karerwa. “We penalise illegal fishing under the law, but enforcement is hard.”
She supports establishing alert systems to help fishers respect closed seasons and buffer zones. Beyond fishing practices, she also highlights the impact of pollution on the lake’s health. “People dump oil into the lake. That has to stop. Legal action is needed,” says Karerwa.
Experts also stress broader reforms: fishing licenses, gear limits, and protection for breeding zones. “We need coordinated management of shared fish stocks,” Ntakimazi says. Lake Tanganyika must be governed collectively.”
Regional efforts exist, including the Lake Tanganyika Authority, which coordinates action among the four riparian countries – Burundi, the Democratic Republic of Congo, Tanzania, and Zambia – to promote sustainable use and joint management of the lake’s natural resources.
For Nkurunziza, public awareness is key: “People must learn that rivers and lakes are not dumping grounds. Local leaders must take the lead in educating their communities,” says Nkurunziza.
Rurihose, the fisherman, hopes for better days. “If the catch improves, I can pay school fees,” he says. “But now, it’s harder every year. Times have changed.”
His reflection sums up a reality many here share – things have changed, and not for the better. But the decline is not beyond repair. With committed efforts from communities, authorities, and neighbours across the lake, Tanganyika could still be steered onto a more hopeful path.
