Water hyacinth spoils the party for cage fish farmers

A fisherman removes water hyacinth from his fish cage at Ugemba Beach in Siaya County. Fishermen in the area say they are making losses due to infestation of water hyacinth at the lake. PHOTO | TONNY OMONDI | NATION MEDIA GROUP

What you need to know:

  • The plant has invaded the lake spreading to places where farmers have set up fish cages.
  • When the cages are covered by the weed, they become excessively rich in nitrogen and phosphorus.
  • Before the invasion, cage aquaculture had become the new way to rear fish in the region as farmers were able to keep thousands of them in their natural environment.
  • Under favourable conditions, the population of water hyacinth doubles daily. If completely undisturbed, it spreads faster over the lake, especially when there are heavy winds.

Dressed in a black shirt and a blue trouser, Kevin Omondi uproots green plants from water and puts them in a boat.

Omondi, with other members of Ugambe Beach Cooperative, farms fish inside cages in Lake Victoria, and his is a desperate move to get rid of water hyacinth that is choking their agribusiness.

On January 20, the group went to the lake early morning as usual to feed their tilapia but could not see the cages.

“At the place where our cages are was a mass of shinning green plants and as we paddled the boat with other three members to check what was happening, we saw fish carcasses,” he recounts.

The plant has invaded the lake spreading to places where farmers have set up fish cages.

“Since the invasion, we have been going round twice a day to uproot the plants because mortality is rising every day,” says Omondi, 30.

In about two weeks, Omondi’s group has lost nearly 90,000 fish and the situation is getting worse because the weed is uncontrollable.

Before the invasion, cage aquaculture had become the new way to rear fish in the region as farmers were able to keep thousands of them in their natural environment.

Over 2,500 cages have been set up in the lake in the last few years, according to data from the Fisheries Department.

Most farmers use simple materials such as plastic drums which act as wave breakers, wire mesh, nets and anchors, with a simple metal cage going for an average of Sh60,000.

SPREADING FAST

“Before the weed we were doing fine. We were harvesting three times a week depending on the number of fish needed by our customers. Sometimes we would harvest up to 40,000 fish and sell each from Sh200,” says Omondi of the business they started in 2011 after taking a bank loan.

Their worry is that the weed is spreading faster and it is becoming hard to contain it.

“This weed is robbing us our livelihoods. We were happy that we had overcome the challenge of lack of fish in the lake which has been brought about by over-fishing.”

The hyacinth has led to decline in fish stocks resulting in high prices. Farmers and fishermen alike are frustrated because they can’t go into the lake, neither can their boats ply the waters to fish.

“Getting fish from the lake is a big problem. We have to travel to other beaches that are not covered and have to pay more for fish,” says George Ayimba, trader.

Winnie Awuor, a farmer at Usenge Beach, says the hyacinth has become a headache.

She started farming in 2013 with five cages and has now grown them to 30, each hosting 2,000 fish.

All her cages are now covered by hyacinth and in a day, up to 2,000 of her fish die.

“Before the menace, I would harvest over 20,000 fish in a week but now the growth is so slow because even feeding has become a problem and I have to wait for long to harvest,” says the farmer, who supplies her fish to customers in Nairobi, Kisumu, Busia, Siaya and Nakuru counties.

ADVERSELY AFFECTS AQUACULTURE

According to Omondi, the weed that was first reported in Lake Victoria in late 90s has affected all the beaches where cage aquaculture is practised.

“Penetrating the weed to reach our farms with boats is a challenge. We cannot access areas where the hyacinth has grown and it moves from one side of the lake to the other depending on the season and direction of wind,” Omondi says.

Under favourable conditions, the population of water hyacinth doubles daily. If completely undisturbed, it spreads faster over the lake, especially when there are heavy winds.

However, as the fish farmers cry foul, researchers are blaming the faster spread of the weed to pollution arising from fish feeds, sewage, detergents and fertiliser leading to low oxygen.

Dr Christopher Aura, the Kenya Marine and Fisheries Research Institute director in Kisumu, says when the cages are covered by the weed, they become excessively rich in nitrogen and phosphorus and are prone to low oxygen.

Therefore, this leads to death of fish in their thousands.

Economic impact

  • The weed blocks boat access affecting smooth transportation.
  • Fishing and fish farming is also negatively affected.
  • Where the plant is widely spread, there is increase in several diseases, as the weed hosts breeding pests like mosquitoes.