October 5, 2011
Culling Won’t Help Tasmanian Devil Populations
Populations of Tasmanian devils in parts of Australia are suffering from Devil Facial Tumor Disease (DFTD) that has wiped out more than 90 percent of individual animals in some areas.
Because of this, the animals have been the subject of a culling, or a purposeful killing of a large number of the animals, with hopes of removing the cancer from the general population. Conservation biologists began the cull in 2004.
However a study in the Journal of Applied Ecology confirms that the culling of sick animals has been ineffectual at stopping the spread of the disease. All trial culls of the devils have now been stopped, BBC News is reporting.
Culling has been successful in controlling infectious diseases in a range of species from deer to badgers, wolves to domestic cattle. However controlling the diseases of livestock, such as foot and mouth, which has proven successful, the culling wild animals is having a more difficult time in proving effective.
Nick Beeton of the University of Tasmania and Professor Hamish McCallum of Griffith University found that an unfeasibly large number of the marsupials would need to be removed from the native population to control the disease.
“For all the models we used, we found the removal rate required to suppress disease was higher than that which would be feasible in the field. Disease suppression can only work if you can catch enough of the infected animals in the population to make sure the disease won´t bounce back,” explains Beeton.
“Our models show that even for a trappable animal like the Tasmanian devil, catching enough of them to eradicate disease is a tall order.”
DFTD was first detected in 1996 in north-eastern Tasmania. Since then the infectious cancer, thought to be transmitted by biting during mating, has spread across most of the animal´s range resulting in a 60 percent decline in population since then.
Two-hundred devils are already captive in Australian mainland zoos. Disease-free populations in large enclosures are also being established in Tasmania and mainland Australia.
Elizabeth Murchison, geneticist from the Wellcome Trust Sanger Institute in Hinxton, UK, studying the devil cancer says, “It´s much better to do a study like this, than spend a lot of money on a huge culling program and then find that it hasn´t worked.”
She added that by confirming that culling does not work, conservationists can then focus their efforts on alternative strategies, such as the captive breeding program and developing a vaccine against the cancer.
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