In Summary
  • Hyacinth is an aquatic floating plant native to South America that has become a global freshwater scourge after being inadvertently transported worldwide.

  • The water hyacinth thrives on chemicals including phosphorus, which is found in high quantities in Lake Victoria due to fertiliser run-off from nearby farms.

  • Agricultural pollution, illegal fishing in spawning grounds and global warming are all affecting fish reproduction and fishermen are seeing their catches evaporate.

With nets piled onto wooden boats, a group of fishermen joke while gazing out across Lake Victoria and the vast green weed clogging up the waterway. But their laughter has a worried edge as the sun sets.

The thick green carpet of water hyacinth is again choking Kisumu bay, floating on the surface and blocking Kenya's main entry to the largest body of water in Africa.

Leggy egrets are delighted, high-stepping through the invasive vegetation in search of food -- but the fishermen are downcast as it is unclear when the weed will clear.

"If we go fishing now we'll be stuck in the hyacinth," says Maurice Omondi, 40, who heads the Kichinjio Fishermen's Association on one of Kisumu's beaches.

"All we can do is wait for the wind to turn and take the hyacinth with it."

"In the past we tried to make it through but it's very, very hard and the risk is too great: Once, we had to get a helicopter to rescue some fishermen stuck in the hyacinth," he says.

Lake Victoria

Car washing on the shores of Lake Victoria, which is infested with water hyacinth. Pollution of the lake has contributed to the growth of the weed. PHOTO | FILE | NATION MEDIA GROUP

GENESIS

Hyacinth is an aquatic floating plant native to South America that has become a global freshwater scourge after being inadvertently transported worldwide.

It is believed to have first reached Lake Victoria in the 1990s, floating down the lake's western tributary, the Kagera.

Since then it has seriously complicated the movement of fishing boats and other vessels on Lake Victoria, hitting the local economy hard.

"Sometimes we go out fishing and can't come back because the hyacinth blocks access to the beach. At other times, the hyacinth takes our nets," says Thomas Ouma, 40, a tall fisherman in a football shirt.

HIBERNATE

Lake Victoria is shared with Tanzania and Uganda, but on the Kenyan side alone hyacinth covers around 17,000 hectares (42,000 acres) -- roughly five percent of Kenya's lake water surface -- a figure that fluctuates with efforts to control the stubborn weed using insects, machines or manual removal.

"The problem is that it is impossible to eradicate the water hyacinth, you can only try to control it," says Christopher Aura from the Kenya Marine and Fisheries Research Institute.

"Seeds can hibernate in the lake bed for between 15 to 21 years," he says, adding that the water hyacinth thrives on chemicals including phosphorus, which is found in high quantities in Lake Victoria due to fertiliser run-off from nearby farms.

Lake Victoria

Water hyacinth chokes Winam Gulf in Lake Victoria, Kisumu County. PHOTO | FILE | NATION MEDIA GROUP

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