Last year saw one of the biggest unexplained wildlife disasters to ever hit the Kruger National Park (KNP). Mass crocodile die-offs in the Olifants and Letaba rivers left staff, scientists and other experts searching for answers. More than 160 crocodile carcasses were found, but it is believed many more died and the carcasses simply washed away or were eaten. The crocodiles all suffered from the same disease, pansteatitis. Pansteatitis results in the oxidisation of the body’s fat deposits, causing them to harden and render the crocodiles immobile. The crocodiles then either die of starvation or drown.
The cause of the Kruger die-offs remains a mystery. Pansteatitis is usually linked to mass fish die-offs, where the crocodiles are then exposed to rancid fish oils, which their bodies cannot break down. These rancid fish oils cause the oxidation seen in the crocodile’s own fat. However, no mass die-off of fish have been observed in the Olifants River or the gorge itself and despite extensive investigations by SANParks, the department of water affairs, and numerous other independent research institutions no obvious causes or triggers to the outbreak could be found.
What became apparent to all who took part in the investigation was the terrible state of the Olifants River and the need to do something about this. Conserving and protecting Kruger’s river systems is proving to be one of the biggest challenges facing park managers, because unlike Kruger’s animals which can be fenced in, Kruger’s river systems aren’t restricted by the Park’s boundaries or even international borders. Whatever happens both up and down stream of the park, impacts on Kruger.
Agricultural and industrial pollution, extensive irrigation and other impacts of human overuse and interference upstream and the recent completion of the Massingir Dam downstream have all contributed to making the Olifants Rivers one of the least healthy river systems in the whole of South Africa.
At a scientific workshop experts agreed on the need for a holistic focus on the river system and adopted an umbrella project that will encompass many smaller studies looking at every aspect of the river system. From micro-invertebrates, to fish eating birds, sedimentation studies to human usage studies, “operation CROC” intends to build the bigger picture of what is really happening in the Olifants River. Since the first carcass was found, experts have tested water, sediment, crocodile and fish blood and tissue samples.