Hippos are an important link in a vital food chain.
"Any animal that eats the enormous quantities of bio-mass, as do hippos eating grass, has an important effect on the ecosystem," said Richard Ruggiero, the Africa program officer for the U.S. Fish and Wildlife Service. "Hippos not only consume lots of grass, but they digest it and deposit it into the aquatic ecosystem, thus fertilizing it," he said.
Each hippo dumps some 60 pounds (27 kilograms) of dung into Lake Edward every day. The dung feeds microscopic plankton, which are consumed by worms and larvae. They in turn feed the lake's tilapia fish, the mainstay of the thousands of fishers who live inside the park.
"The equation is clear: Less hippos means less manure, less manure means less fish, and less fish obviously means huge problems for the fishermen of Lake Edward," said WWF's Languy.
At the same time, tens of thousands of people have come to squat illegally by Lake Edward. About 800 boats are legally registered and entitled to fish in the lake, but there may be at least 2,000 boats operating there now.
Many of these fishers are using illegal gear, including fine mosquito nets, to catch tilapia. A decade ago, fishers averaged one to two tilapia per kilogram (2.2 pounds) of catch, a number that has now increased, as fish stocks decline, to seven to eight per kilo.
"This is symptomatic of over-harvesting a limited population," said Muir of the Frankfurt Zoo, adding that more than 30 fish species have already gone extinct in Lake Edward. "There are clear signs that the fish population is now collapsing."
The zoowith funding from the European Union, UNESCO, and the U.S. Fish and Wildlife Servicerecently hired Conrad Thorpe, a former British Royal Marine, to provide hundreds of local rangers with anti-poaching training. Thorpe has set up camp inside the park.
"Our job is to dominate the ground and prevent the army from carrying out their acts of killing [hippos]," Thorpe said.
He says many soldiers see no problem in supplementing their nonexistent rations with wildlife meat, because "animals are wild so no one owns them."
But protecting wildlife is dangerous work. Many locals despise the rangers. Local police, who in many cases are running illegal activities inside the park, also see rangers as problematic.
"As a rule of thumb [the rangers] are persona non grata everywhere," Thorpe said. "They cannot drink or eat in some villages for fear of poisoning in food or drink."
Led by Thorpe, park rangers have stepped up patrols and are currently clamping down on illegal fishing activities through a series of antipoaching operations.
There are signs that security is improving. While there were at least 13 attacks on patrol posts and park stations in 2004, there have only been a couple of attacks in 2005.
Last month, thousands of Congolese troops and Indian peacekeepers, who are in the DRC as part of a UN peacekeeping mission, also reportedly carried out an offensive to oust militias suspected of animal poaching.
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