Cage fish farming on the rise as wild stocks dwindle amid high demand

Research by the Kenya Marine and Fisheries Research Institute (KMFRI) shows that Lake Victoria fish catch on the Kenyan side has declined by half, drawing attention to the seriousness of the problem and prompting farmers to seek new ways to increase stocks.

The fish stock has fallen to 2,500 metric tonnes (MT) annually from 5,000MT with major causes of the decline being over-fishing, illegal fishing gear, fishing in breeding grounds, water hyacinth and pollution.

But this fall is accompanied by yet another decline in local fish consumption, even though the most recent data is not available.

The Food and Agriculture Organisation said last year that local fish consumption has been declining from a modest six kg per capita in 2000 to 4.5 kilos per capital five years ago.

With declining wild stocks and high demand for the tilapia species, producers around the lake are fast turning to the cage farming system as an alternative.
“Cage farming, if done properly, will supplement demand for fish and at the same time reduce the pressure on over-exploiting wild stocks,” says Dr Christopher Aura, the KMFRI director in Kisumu.

There are 2,500 cages spread across counties bordering Lake Victoria such as Kisumu, Siaya, Homa Bay, Migori and Busia. Siaya County leads with 800 cages. The ownership of the cages is by individual or groups.

Cage aquaculture is a fish rearing system where fingerlings are put into metal or plastic cages — to protect them from predators — providing them artificial feed and harvesting them only when they are mature.

The fish are in their natural habitat where there is exchange of water. In Kenya most farmers use simple materials such as plastic drums which act as wave breakers, wire mesh, nets and anchors. Metal cages can cost at least Sh60,000.

Winnie Owuor, a cage farmer at Anyanga Beach in Bondo, Siaya County, has 600 cages measuring 2x2 metres, located almost 10 metres from the lake shore.

“Although the initial cost of setting up cages is high, the enterprise is promising and the returns are rewarding,” says Mrs Owour.

She says that she stocks 1,500 mono-sex fingerlings in her cages which mature after six months.  

“Initially I would stock up to 2,000 fingerlings but I realised that there was high mortality and slow growth because of limited space and competition for oxygen and feeds,” she says.

Dr Aura says that over-stocking cages results in limited individual fish movement and may lead to choking. Getting high quality feeds is a challenge hence most farmers, in an effort to cut costs, tend to make their own.

Fish feed producer Aller Aqua Kenya Limited partner CEO Marius Them-Enger says that cage farmers should not compromise on the quality feeds and fingerlings.

“Tilapia fish are top feeders therefore you use extruder floated pellets. If you want quality feeds you have to pay for it. Using high quality feeds has direct impact on the food conversion ratio,” says Mr Them-Enger.

Feeds that sink, he says, cause decomposition which compromises water quality and oxygen levels. Mrs Owuor uses imported high quality feeds for her tilapia stock.

‘‘The growth rate has increased significantly unlike previously when I used local feeds,’’ she says.

“Local feeds tend to lack essential nutrients, minerals and additives. As a result, fish take longer to mature which can be frustrating for a farmer,” she says. She has ready market in Kisumu, Siaya, Kakamega, Nairobi and Eldoret.

The fish are harvested at between 350g and 800g with prices ranging from Sh150 to Sh350 each.

Automated system

Otieno Okello runs a hatchery and grows tilapia at a cage farm at Pioneer Fish Farm in Maseno. He uses the re-circulation aquaculture system, a method of rearing fish in vessels under a controlled and automated system for quick yields.

With a two-year course in aquaculture at Rhodes University in South Africa, Mr Otieno produces about 500,000 tilapia fingerlings every month which he sells to farmers in Kisumu, Bungoma, Busia, Vihiga, Kakamega, Siaya, Kisii, Homa Bay and Nyamira counties.

Mr Otieno has 6mx6m cages which can stock up to 12,000 fish. “We will never have wild stocks the way we used to. We have to look at an infinite system which is the cage method. The wild catch is unsustainable,” says Mr Otieno.

He added: “The wild catch is exhausted, just go to the beach and see the number of kilogrammes fishermen bring in per day. It will get worse because there are too many fishermen chasing too few fish in the lake.”

Not every part of Lake Victoria is ideal for cage fish farming. The Fisheries Department and KMFRI have developed a suitability map for cage fish farming around Lake Victoria.

“If you want to do commercial cage fish farming suitability is important. Check on the depth of the water and keep off navigation routes and breeding areas.

‘‘You need water depth of six to eight metres and fish, just like any other animals, discharge waste. With enough depth the water current should carry way the waste,” says Dr Aura.

He says that demand for fish will grow as the population rises, adding that today people are more conscious of their health and that’s why cheap Chinese fish imports have found a market in Kenya.

‘‘We should be aggressive in fish production and use modern techniques,’’ he says.

‘‘Fish won’t come from ponds and wild catches alone, we have to embrace the cage system. In the next five years the biggest catches will come from cages if we farm in a sustainable way.”

The water hyacinth is a big threat to cage fish farming. Often, where there is hyacinth navigation becomes a challenge for farmers who use boats to access the cages.

“The hyacinth brings with it a lot of predators at the bottom. If you have no access to your cages that becomes a problem,” says Dr Aura. 

In addition, the hyacinth fights for the same resources with fish such as oxygen, which can lead to disastrous consequences. 

“It’s something that can be addressed, it requires political goodwill; how many countries have hyacinth and have managed it effectively? It needs dedication by both the national and county governments to provide solutions,” says Mr Otieno.

Dr Aura says that if one understands wind patterns on Lake Victoria one can predict water hyacinth movement. 

“When the water hyacinth infests cages it renders water stagnant, therefore there is no water exchange hence minimal oxygen. In addition the hyacinth utilises the available oxygen and eventually causes fish to die,” he says.

Upwelling refers to when currents flow from the bottom and bring up cold water with less oxygen to the top and take warm water to the bottom.

Suffocates fish

The process suffocates fish.

“In the event the dead fish is not carried away it settles at the bottom of your cages,” says Mr Otieno. 

He urges the government to establish an aquaculture park to deal with such hazards.

“If the Fisheries Department and KMFRI know the location of the cages, it’s easy to control the spread of diseases. Ideally, cages in the aquaculture park should be two kilometres apart. Each park should get National Environment Management Authority certification, KMFRI authorisation and county governments should know about them; that way it’s easier to check on the quality of feeds and fingerlings,” he says.

Two unique circular high-density polythene fish cages have been established at Ramba Beach in Homa Bay County.
The cages are owned by Lake View Fisheries Limited, a family business. 

The company runs a tilapia hatchery, 31 ponds, two demonstration cages, two circular polythene cages and makes extruder floating pellets.

With capacity of 25 tonnes of fish, each cage is made of high density pipes surrounded by green nets, has a diameter of 20 metres and depth of six metres.

Dr Gilbert Mbeo, one of the directors of the company, says that with installation of the polythene cages pressure of over-fishing in the lake is reduced.

“There’s a lot of wild fishing which has depleted fish stocks. But through cage fishing people will be able to get farm fish in a sustainable way,” he says. 

The cages have a series of up to four nets: the actual net that holds the fish, the predator net, the feeds net to contain feeds so that they do not spill out, and the bag net which covers the cage preventing predators such birds.

“When we decided to go with this style of farming we knew we have to reach out for expertise because such cages have not been seen in Kenya. We currently consult experts from Africa’s biggest cage farms to understand best practices on cage management,” says Dr Mbeo.

Before fish are released into cages in the lake, eggs are hatched in an incubation room. With brooding stocks of 2,000 tilapia the company currently produces over 100,000 sex-reversed fingerlings per month. Each fingerling costs between Sh5 to Sh10 depending on size.

“We went through several months of developing our brood stocks which involved cycles of breeding and selecting the most favourable genetics and traits fit for cage farming,” says Michelle Mbeo, a co-director of Lake View Fisheries Ltd.

When the fingerlings are a month old they are transferred to a nursery and fed on mash and small pellets for two months until they reach 5g. They are then transferred to square cages. Tilapia are top feeders so they are fed on floating pellets until they reach table size.

“We stocked both circular cages with 100,000 mono sex tilapia fingerlings in April. The other two square cages measuring 4m by 4m can stock 7,000 fish each,” says Ms Mbeo.

About three tonnes of fish are harvested on the farm twice per week in different sizes ranging from 350g to 700g.
The farm gate price of one kilogramme of fish is about Sh300. The fish is sold to hotels and restaurants in Kisumu, Homa Bay, Mbita, Migori, Kakamega and Nairobi.

“Through research we learned a lot about pond and cage farming. We realised that we can keep a large number of fish in a small area on the lake compared to the pond, that’s what made us focus on cage fish farming,” says Dr Mbeo.

The two directors admit that it is an expensive venture. The started off with passion and Sh100,000 capital and have nurtured the venture into a major enterprise. With the help of their parents they pooled resources to expand the business.

“Michelle works in an information technology firm while I am a neurologist based in the US. We both tapped our savings to support the start-up,” he says.

Most of the funds went into getting licences and permits, community sensitisation and construction of a fingerling hatchery, fish ponds, an administration block, training staff and buying necessary machinery.

Lack of financial support and expensive feeds and cages are other challenges for the company. 

“For the first few years we reached out to different lenders and investors to seek funding. Although most of them were excited about the prospect of this novel approach to sustainable fish farming, they were unwilling to offer us financial support,” says Dr Mbeo. 

Some of the common diseases to watch out for include Bacteria tail and Fin rot which attack fish reared in both ponds and under the cage system.

“Fin rot is associated with polluted and unsanitary conditions in the hatcheries. Management practices such as cleaning the nets and cage clocking will improve water circulation and oxygen in the cages,” Dr Aura says. 

Dr Aura says that the enactment of The Fisheries and Development Act 2016, which advocates for co-management of fisheries while helping deal with cases of over fishing, has been beneficial.

“We want all stakeholders to be involved in the management of fisheries, especially the beach management unit. If this resource belongs to you, you should take care of it for the next generation. We are keen on the types of net used for fishing, some nets harvest juvenile fish which is wrong,” he says.

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