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TAS Country : December 16th 2010
8 Tasmanian Country Friday, December 17, 2010 YOUR SAY firstname.lastname@example.org Fox fight poses minimal devil danger DOSE: A Tasmanian devil has to ingest about 10 baits before it dies. Itcanbeseen that the risk to Tasmanian devils is extremely small.' Continued Page 11 I WISH to correct inaccuracies pres- ented in a letter about the fox eradi- cation effort in Tasmania (Tasmanian Country, December 10). The inaccuracies are misleading and misrepresent the serious issue of the eradication of foxes from Tasmania. The Fox Eradication Program (FEP) baiting strategy is specifically designed to target foxes in the Tasmanian environment and to pose minimal risk to native species. Sodium fluoroacetate (1080) is a naturally occurring chemical found in some plants as a natural defence against over grazing. Australia's native animals, including Tasmania's, have a higher tolerance to fluoroacetate than canids (dogs and foxes). When this toxin is used in large dosages it is a knockdown poison, however when used in very small dosages it becomes species selective due to the high susceptibility of foxes to the toxin. The baits used for fox baiting programs contain 3mg of 1080 per bait. Across mainland Australia, 1080 meat-based baits are widely used in baiting programs to control fox popu- lations. These programs are generally at the landholder's expense and are vital in minimising damage to agricul- ture such as lamb and poultry kills and damage to fences/irrigation and other infrastructure. The costs incurred are an annual expense to the landowner. The letter writer correctly notes that the Tasmanian devil maintains an LD50 of 4.24mg but he raises questions about the number of baits a devil would need to consume to ingest a lethal dose. The LD50 is the amount of 1080 (in mg) per kilogram of body weight required to give a lethal dose to 50 per cent of individuals. Research confirms if you translate the LD50 of the average healthy devil of 7kg to the number of baits required for 50 per cent of individuals to ingest a lethal dose it means the devil would indeed need to consume 29.68mg of 1080 which equates to 10 baits. This does not consider measures implemented by the FEP to further reduce risks to native wildlife. Fox baits are buried to reduce the chance of uptake by native species and they are also spaced on average be- tween 200m and 250m apart. So for a healthy 7kg devil to ingest 10 baits he must travel approximately 2.2km, find each bait, dig them up and consume them. All within a 24-48 hours for there to be a 50 per cent chance of mortality. Added to the fact that 1080 is biodegradable and after two days in the ground there is only 56 per cent of the 1080 left in the bait (still enough for a fox to receive a lethal dose), a healthy 7kg devil would need to travel 4.6km and consume 23 baits to have a 50 per cent chance of receiving a lethal dose.
December 9th 2010
December 23rd 2010