What is killing fish in Uganda’s lakes?

For the past month, Uganda has recorded mass death of fish in Lake Victoria.

While Wakiso district was the most affected, the death is spreading to other parts of the lake in Mukono and Kalangala districts. So far, the Nile perch, which is the most valuable fish in Uganda’s shared Lake Victoria, is affected.

Smell of death

There was a foul smell, lifeless Nile perch floating on a seemingly dead part of the lake, and green water similar to green paint. This is what welcomed our team on a fact-finding mission to Lake Victoria near Kigungu landing site in Entebbe on Friday.

According to the fishermen, the smell is caused by decaying fish as well as the green matter (algae) which fishermen call Mubiru in the local dialect. This, according to the fishermen, grows on the lake during the dry spell.

Scientists say the algae are food for fish, but the carpets of green matter which look like paint are referred to as eutrophication.

Scientists say it is caused by the excessive richness of nutrients in a lake due to run-off from the land, which causes a dense growth of plant life.

As our boat manoeuvred through what has become a death field on the lake, birds were feasting on the dead Nile perch.

The massive fish deaths have also been reported in Kenya, but Uganda’s scale of death remains unmatched, according to a recent statement from the agriculture ministry. Tanzania has not reported any death of Nile perch.

“As a result, fish catches have dropped as well as the price of fish,” said Patrick Serunjogi, a fisherman and resident on Kavenyanja Island in Wakiso.

Serunjogi said the death has claimed all ages and sizes of Nile perch. The old, young, big, or small Nile perch have perished.

Sand mining and fi ltering taking place close to Lake Victoria’s shore.

He added: “I do not see the recovery of the fish sector in the coming year because the death is not sparing the young Nile perch and it is spreading to other parts of the lake.”

The LC1 chairperson for Kigungu, Musa Yiga, said the death of Nile perch is affecting the value chains of fish and the local economy at the landing sites.

“When the fishermen do not have money to spend, there is little business for dealers in different items,” he told New Vision in an interview over the weekend.

The worrisome situation at Kigungu is replicated at Bugonga landing site, which is one of the first areas that reported the death of fish on the lake.

“We are no longer fishing,” said Sarah Ddungu Ibaale, the LC1 chairperson for Bugonga LC1, adding that when the fishermen set the nets, they end up catching nothing.

“Even the hooks do not catch anything,” she said, adding “we have lost our future and the coming months will not be easy for fishermen.”

This has brought the bustling landing sites, including Bugonga, Gerenge, and Kigungu to a standstill.

“It is going to affect the economy because tonnes of fish are being turned away by the factories because of low quality,” Ddungu said.

In the last 15 years, the fisheries sector has played an important social and economic role in Uganda as the second largest foreign exchange earner, contributing 2.6% of GDP and 12% to agricultural GDP.

In addition, landing sites such as Kitobo and Jaana in Kalangala have also been hit, according to Ddungu.

The fish maw, also known as the swim bladder, which fetches more revenue, has also dropped in price.

“The fish maw of 2kg used to go for as much as sh3m before the massive death, but now it fetches only sh200,000,” said Ddungu, adding that this is because the fish is rotten.

The economy is going to suffer because fish is a source of income for the fishermen and Uganda’s economy. Nile perch fillet is one of Uganda’s leading exports to Europe, according to Ddungu. 

Fears of poisoning

While there are fears that the massive death could be due to poisoning, experts have ruled this out.

The death of Nile perch (mpuuta) on Lake Victoria and Kyoga is the result of environmental changes, according to Pius Kasajja, the permanent secretary in the agriculture ministry.

“Based on the findings from the three different laboratories, we have concluded that the cause of the fish deaths is not poisoning rather it can be attributed to environmental factors,” Kasajja said.

The death of fish, according to Kasajja, was caused by a normal phenomenon (known as Kaliro), that occurs almost every year. He also said it has no impact on the taste of the rest of the fish in the lake.

“This is to, therefore, reassure fish consumers that there is no harm in eating the lake’s fish,” he said at the Media Centre in Kampala recently.

Kasajja explained that recent storms on the lakes caused mixing of the different waters thereby reducing the amount of oxygen in the lake. Nile perch suffocates when exposed to low levels of oxygen.

Kasajja said the death of fish is a result of severe weather patterns last year. He also said the extent of fish kills reported this time is higher than before. The current fish kills have been reported both on Lake Kyoga and Lake Victoria.

“Fish kill is an annual phenomenon that usually occurs on Lake Victoria and is associated with weather patterns,” the permanent secretary said, adding that further investigations were taking place.

Illegal fishing

As the massive death claims the Nile perch, fishermen were hoping to turn to tilapia.

However, tilapia has also become scarce probably due to illegal fishing that has hit the lake in recent weeks.

“Illegal fishermen have invaded the lake with wrong nets, which are devastating to tilapia,” Ddungu said.

Regarding illegal fishing, Yiga said the illegal fishermen use hoes, which they tie onto ropes and strike the water in order to scare fish into their nets.

What can be done?

As officials of agriculture ministry carry out further investigations, Stephen Sebuliba from Lake Victoria Region Local Authorities Co-operation (LVRLAC) says there is a need to manage solid waste from municipalities and also siltation caused by run-off, which he called the leading cause of contamination in the lake.

LVRLAC is a network of local authorities in the Lake Victoria Basin (Uganda, Kenya and Tanzania). Uganda alone has about 230 local authorities.

In addition, the water ministry, under the Lake Victoria catchment management, is engaging different actors to manage the catchment of the lake.

The catchment includes River Rwizi, which originates from Buhweju and pours its water into Lake Victoria.

“We are working with the ministry and districts in western Uganda where the catchment of Rwizi is located as well as the private sector and communities to restore forests and wetlands,” said Onesimus Mugyenyi, the deputy director of Advocates Coalition for Development and Environment.