Botswana gets Thailand's help with mystery fish disease

Fishing at the Okavango Delta is an important socio-economic activity

Flickr/lawmurray

[GABORONE] A lack of laboratory equipment and technical expertise has left Botswana unable to find the cause of a fatal disease that is ravaging its largest and most important fishery.

Fishing is the main source of protein and revenue for many people in the Okavango Delta in the north of the country. This makes fishing an important socio-economic activity in the area, according to Keta Mosepele, a senior research fellow at the Okavango Research Institute.

But now the fish — mainly the commercially important tiger fish and the catfish — are dying in the Okavango Delta and in nearby Lake Ngami. The Botswana National Veterinary Laboratory in Gaborone has been unable to identify the disease.

Botswana has now turned to Thailand for help: it shipped samples there for testing in late September, according to Chandapiwa Marobela, a veterinary microbiologist and the laboratory's acting deputy director. It is now waiting for the results.

A senior wildlife officer at the Ministry of Environment, Wildlife and Tourism Shaft Nengu said Botswana has been collaborating on research with Thailand through the UN Food and Agriculture Organization.

The outbreak was first reported in May, when fishermen found dead fish in both the delta and the lake. Infected fish grew large sores and eventually died from secondary infections.

The discovery was reported to the Department of Wildlife and National Parks, which collected samples of dead fish and passed them to the laboratory in Gaborone for tests. But staff at the laboratory has been unable to establish the type of disease.

Marobela attributed the failure to a lack of infrastructure, human capacity and funding. "We don't have the right equipment and competency," she told SciDev.Net.

She added that the National Veterinary Laboratory has no specialists on fish diseases and that the country lacks good fisheries research departments because of a shortage of government funding.

Marobela also said this was not the first time the laboratory had been unable to diagnose fish diseases. During the last outbreak of fish disease in 2007, which turned out to be epizootic ulcerative syndrome, a seasonal disease caused by a fungal infection, the laboratory also sent samples to Thailand. But there has been no improvement in Botswana's capacity to diagnose fish disease since, she said.

Isa Alidi, a senior wildlife officer at the Ministry of Environment, Wildlife and Tourism, said they suspected that the disease originated upstream in Angola and Namibia.

Alidi, who is based at the delta, said the fish are still dying, although exact numbers are not yet known. But he said his division could do little to help, as Botswana has no fish pathologists: "We have only three scientists but their focus is mainly on fish stock assessment".

Despite the outbreak, Alidi said, fishing has been allowed to continue in both Lake Ngami and the delta, but people have been instructed not to eat or sell infected fish.