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KRUGER National Park has reported a high rate of crocodile deaths in the Lepelle River - formerly known as Olifants River.
So far, 13 carcasses have been found this year. Last year 170 were discovered.
The park's head of scientific services Danie Pienaar said yesterday researchers and game rangers were calling for more collaborative efforts to ensure that South African rivers were clear of pollution as more crocodile carcasses were discovered in the Lepelle River.
"It is unlikely that management actions which are taken inside the KNP can solve this problem.
"One would need a much larger and overarching restoration programme for the entire Lepelle River system, which should focus on issues such as acid mine drainage, agricultural pesticides and fertiliser use, sewerage treatment and industrial and household sources of pollution," Pienaar said.
He said apart from the carcasses, game rangers and scientists had found many sick crocodiles in the river near the Olifants Rest Camp.
Pienaar said aerial surveys showed that there were a total of 385 crocodiles in the Lepelle Gorge and lower Letaba River.
"Our research has shown that these crocodile mortalities are now a recurrent problem that is likely to occur every winter.
"If mortalities continue at this rate, there will be very few crocodiles in the lower Lepelle and Letaba rivers by 2010," he added.
Pienaar said that in May 2008, crocodiles in the Lepelle River gorge in the park started dying, with a mortality rate of 20 crocodiles a week reached during June and July.
A total of 170 carcasses have been recorded by November 2008. Post mortem examinations revealed yellow-orange coloured, hardened fat in the tails and abdomen - a condition known as pansteatitis.
Pienaar appealed to communities to refrain from polluting the rivers.