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Tuesday, 17 February 1987
Page: 31

(Question No. 1541)

Senator Jones asked the Minister representing the Minister for Primary Industry, upon notice, on 19 November 1986:

(1) What was the estimated rabbit population in Australia in the following years: 1984-85; 1985-86.

(2) How serious is the threat, present or potential, to the Australian agricultural industry.

(3) What measures are in force, or foreshadowed, or contemplated to control rabbit numbers.

(4) Will the Minister give an assurance that any form of germ warfare such as the infamous Myxomatosis campaign of the 1950s will not be part of any plan to control the proliferation of rabbits.

Senator Walsh —The Minister for Primary Industry has provided the following answer to the honourable senator's question:

(1) It is impossible to give an accurate estimate of the Australian rabbit population. Rabbits occupy a wide range of habitats, and soil types and seek shelter in warrens or in thick undergrowth. Warren and night spotlighting counts give population estimates from 0-5 animals/sq km in areas of low infestation to more than 2000/sq km in high density areas.

A CSIRO study has put the 1985-86 rabbit population for the Northern Territory alone at 50 million. This is in an area considered as marginal habitat for rabbits and experiencing severe drought conditions. No details are available for the other States.

(2) Rabbits currently pose a substantial threat to Australian agriculture. The greatest economic loss is caused by pasture damage. Approximately 10 rabbits eat as much as one sheep and 50 as much as a yearling steer. In times of drought this consumption becomes most serious. Rabbits also physically damage the environment by burrowing and may induce severe erosion which varies from exacerbation of gully erosion in high rainfall areas to sheet and wind erosion in the semi arid zones.

Given the rabbit's capacity for rapid reproduction under good conditions, these problems can develop quite quickly. The cost of even a moderate infestation can be very large to the primary producer in terms of crop, meat and wool production losses and the implementation of controls.

The seriousness of the rabbit threat is increasing, due mainly to the recent downturn in the rural economy where landholders are less inclined to carry out labour intensive and expensive control procedures and a rise in the resistance of rabbits to a less virulent Myxonia virus.

(3) The main methods presently used for controlling rabbits are:

poisoning, using baits (usually diced carrots) and 1080 (mono-sodium fluoroacetate) or Diaphacinone.

fumigation of burrows using Phostoxin (aluminium phosphide) or chlorpicrin.

shooting and trapping by commercial operators.

myxomatosis. Biological control using the Myxonia virus transmitted by mosquitoes and rabbit fleas.

Warren ripping. The destruction of burrows and large colonies using bulldozers.

blasting. Using explosives to destroy warrens in stony or hilly areas where ripping is impracticable.

netting and electric fencing. These methods restrict the movement of rabbits, confining them to areas where other control methods can be employed.

Properly applied these methods can keep Australia's rabbit population in check. There are no new control techniques on the horizon.

(4) Before the introduction of Myxomatosis into this country in 1950 the rabbit population was in excess of 500 million. The Myxonia virus reduced numbers by 99% during the following three year period. One of the most noticeable direct results was an increase in the national wool clip by 32,000 tonnes in just one year. Myxomatosis is an example of a species specific, biological control agent that saved the rural sector many millions of dollars per year. Attenuation of the Myxonia virus has produced field strains with a reduced virulence and the control rate has now fallen to around 40%.

However Myxonia is still regarded as the main contributing factor in the control of rabbits in Australia and without it primary producers in remote areas would have no chance of controlling rabbits.

Therefore an assurance cannot be given that if another biological control agent was found, it would not be used to keep numbers at a manageable level. The rabbit problem is not as grim as it was before myxomatosis but in these times of extreme economic hardship in the rural community any alternative to some of the labour intensive and expensive control measures presently used would have to be considered on its scientific and economic merits.