Where have they all gone? – crocs in Kruger

IMG_0726 (1280x960)There’s 2 things going on here.  First is that the crocodiles in Kruger Park’s Olifants and Letaba Rivers started dying off in the winter of 2008 – 170 of them found dead from May to November that year, an unknown additional number dead and washed away or eaten by their colleagues.  Pansteatitis, an inflammation of fatty tissue and conversion to a form that cannot be metabolized was the problem.  But what caused the pansteatitis or created the internal stress that allowed the disease to take hold? Retrospective analysis of 2007 samples from live crocs showed the first signs of the disease in the population.  Investigators began contemplating upstream influences; pollution from upstream industrial and agricultural sources. This caught my interest as a former water quality fisheries biologist responsible for investigating “spills, kills and thrills” on Vancouver Island.  Also, neighbouring Mozambique had activated a downstream dam that backed up water settling large quantities of silt.

The second thing that is going on, is that new reports of crocodile mortality have disappeared from the web and media and largely from public attention.  A Google News search at this time (Feb. 2013) turns up no new references.  A broader Google search for web sites turns up mostly old news from 2008 and 2009.  For example, there is the South African National Parks official website archived news media release from June 2009 indicating that deaths had resumed that year.  Searching the SanParks website turns up a scientific presentation at the 8th Annual Savanna Science Network Meeting of 2010 confirming that the mortality cycle was repeated in 2009.  Also see the article in the Scientific American, Oct. 2009.  But where are the media updates and news releases since then?  Noticeably absent.  The exception is a private web article What is killing South Africas crocs by HopeOnline dated June 2012 although it is difficult to determine what period the information in that article refers to.

Has the mortality cycle stopped?  Or has the national parks service bureaucracy muzzled the researchers?  After all, it reflects poorly if one of their park’s major predators is dying off in large numbers – one estimate was that 60% were “missing” from some areas of the park.  Reports like that could affect tourism or draw unwelcome attention from conservation groups.  Or maybe the government itself finds the topic of the potential impacts of a dam in a neighbouring allied country, or of possible unmanageable sources of pollution from upstream industrial and agricultural interests to be too sensitive to discuss in public?  If you have links to more recent information about crododile deaths in Kruger Park, please pass them back this way.  I’m still looking for it.

Found another item: CSIR Researchspace reference to a publication attributing the crocodile deaths to dam enhanced populations of an unidentified fish species that is somehow encouraging pansteatitis development in crocs and piscivorous fishes.  On the other hand, a crocodile husbandry publication indicates on page 219 that steatitis fat necrosis may result from vitamin E deficiency.