SUNDAY INDEPENDENT (Johannesburg, S Africa) 10 August 08 Why are Kruger crocs dying? (Eleanor Momberg)
Kruger National Park scientists, researchers and veterinarians are baffled as to what has killed more than 130 crocodiles in the park's Olifants and Letaba rivers in the past two months.
Raymond Travers, a park spokesperson, brushed off as speculation reports that the deaths had been caused by mining near the park, or by pesticides used by farmers cultivating crops along the banks of the two rivers.
"We have tested for everything. We have looked at anything that could have possibly had an influence, but all the tests have been inconclusive," he said.
Tests did show that there were high levels of a number of pesticides in the Olifants River, but they were not high enough to kill crocodiles.
Danie Pienaar, the Kruger Park's head of scientific services, said that blue-green algae could be ruled out as the cause of the deaths and that the water in the Olifants River was safe for drinking.
"So far, 130 crocodile carcasses have been found," said Travers. "Every week we seem to find more when we fly over the area."
The Olifants and Letaba river system has the largest population of Nile crocodiles in the park.
Pienaar said it was clear that the Olifants River was under strain. It is the most polluted river in the park.
This week, the scientists, researchers and vets teamed up with Dr Fritz Huchzermeyer, a crocodile expert from the World Conservation Union, and specialists from universities and other institutions, for yet another attempt to unravel the mystery.
"Though we learnt a lot during the operation, we have not found the exact cause of the pansteatitis [inflammation of fatty tissue] that has caused the deaths of so many crocodiles in this river system," said Pienaar.
Travers said that during the three-day, three-night operation autopsies were done on a number of crocodile carcasses found on the banks of the two rivers, and 11 live crocodiles were captured for examination.
This was the first time that such a large-scale night-capture operation had taken place in the park.
"A new theory being investigated is that [healthy] crocodiles are preying on the carcasses and getting infected from eating [diseased] fat and tissue.
"In order to break this cycle, we have taken the decision to remove the carcasses from the water and burn them," Pienaar said.
So far, 10 autopsied crocodiles have been burnt.
Travers said the park's wildlife vets had taken blood and tissue samples from the 11 reptiles captured this week, then tagged and released them.
"Though we didn't manage to capture our goal of 30 crocodiles, the operation has given us an idea of the rate of infection at the confluence of the Olifants and Letaba rivers.
"Seven of the 11 captured crocodiles were found [to be infected]," said Pienaar.
He said that the high infection rate meant that a large number of crocodile deaths in the lower Olifants and Letaba rivers could be expected.
Why are Kruger crocs dying?