A decline in hippo numbers has led to the decline of fish stocks

The international conservation group says there are fewer than 900 hippos left in the Virunga National Park.

Thirty years ago there were 29,000 hippos in the park in eastern DR Congo.

The WWF says poaching by poorly paid Congolese soldiers and local militia groups has been responsible for the decline in the population.

Dung nutrients

These figures are the result of a survey by the Congolese Institute for the Conservation of Nature (ICCN), the European Union, and the WWF.

Hippos can be bought for around $50, and hippo canine teeth often end up as part of the illegal ivory trade, the WWF says.

If this is not taken seriously, this will not only lead to an environmental disaster, but also to an economic crisis for local communities WWF's Marc Languy Battle for Congo's wildlife

"Soldiers are left in the park without being fed or paid and that's a recipe for disaster," said Marc Languy of WWF's Eastern Africa Regional Programme.

"The Congolese government must urgently remove the army from this protected area and ensure that ICCN staff can continue with their official mandate to control the park."

The decline of the hippo population has affected the thousands of fishermen living around Lake Edward, inside the national park.

Hippo dung provides nutrients for fish, and the reduced number of hippos has led to a rapid decline of the lake's fish stocks.

"If the government does not take the hippo situation in Virunga seriously, this will not only lead to an environmental disaster, but also to an economic crisis for local communities," Mr Languy said.

Created in 1930, Virunga Park stretches 8,000 sq km along DR Congo's border with Rwanda and Uganda.