Paradox of the pig:feral status and control in the Wet Tropics

Few environmental issues within theWet Tropics World Heritage Areagenerate the level of contention as doesthe feral pig (Sus scrofa). In the past,control and management strategiesfor these animals have been as varied,numerous and disconnected as theagencies, individuals, industries andcommunities who are directly orindirectly affected by them.

Issues surrounding feral pigs rangefrom environmental, economic andsocial impacts through to health,medical, veterinary and cultural con-cerns. Potential solutions for controlare equally numerous, but none isreadily accepted by all stakeholders aswholly efficient, necessary or even asaddressing what is seen by differentsectors as their main priorities. Theferal pig problem is much morecomplex in this region than anywhereelse in Australia.

Environmental impactsThe WTWHA contains some of themost diverse, complex and ancientecosystems in Australia. Pigs arecertainly the most visible and signifi-cant introduced animal species in thisecosystem. Their ecological impactsinclude soil disturbance, preying uponand competing with native animalsand plants, and contributing to thespread of weeds and exotic fungi.Feral pig diggings along streams androadsides in an otherwise naturallybeautiful environment also create anaesthetic impact that is not easilyoverlooked.

Economic and social impactsHorticultural crops suffer significanteconomic damage from pig activity.This impact is compounded by tensionbetween landholders and authoritiesover the management of the WetTropics Area. Those farmers whoconsider the feral pig a complete pest,can no longer hunt these animalsonce they enter World Heritage land,and they now view this land as a safebreeding ground for the pigs.

Human and animal health risksPigs are well known as carriers ofdisease and the potential of the northQueensland feral pig herd to host andtransmit a range of exotic diseasesthreatening to both human and animal

health is of growing concern. Japaneseencephalitis is a potentially fatalhuman disease spread by mosquitoesand pigs. In this case, the pigs amplifythe disease and increase the likelihoodof transmission to humans. Otherlivestock diseases such as Foot-and-Mouth could become endemic if theyarrive and establish in the feral pigherd. Such an event would havecrippling consequences for the meatexport industry in Australia.

Not everyone wants pigs deadThese impacts notwithstanding, theeradication of feral pigs would haveadverse economic and culturalimpacts on other sectors of thecommunity. Pig hunting is not only asignificant recreational activity butalso supports individuals involved inthe wild game industry. The removalof such livelihoods could have a severeeffect on the economies of some smallrural communities.

Pig hunting for human consumptionis also fundamental to many remoteAboriginal communities on CapeYork. Feral pigs provide a high-quality, low-cost food source to thesepeople and are culturally significant inthe maintenance of traditional formsof wildlife harvesting and interactionsof people with country.

Eradication of feral pigs would causeeconomic hardship and culturalimpacts to these communities whowould understandably, oppose such apolicy.

The feral pig (Sus scrofa)

May 2001

Such concerns and interests are obvi-ously in direct opposition to thosedescribed above, creating a potentialsource of tension between governmentand community with regard to thecontrol and management of feral pigsin the Wet Tropics.

Possiblity of EradicationExperience has shown that eradicationof pigs over wide areas is not practi-cal, and even sustained reductions inpopulation sizes are difficult toachieve. Feral pigs are adaptable, canthrive in a range of habitats, are highlymobile and have a high reproductivepotential. Several conflicting factorsalso need to be considered:• Feral pig control by conventional

means is expensive and becomesmore so as their populationsbecome sparser. Trapping pigs inAustralia can cost up to $100 perpig but they persist easily in in-accessible areas and recoverquickly from any reduction innumbers either by immigration orreproduction.

• While feral pigs are known tocause economic damage to horti-cultural industries, this has notbeen quantified and thereforecannot be offset against the cost ofcontrol. Pig damage tends toaggravate farmers during a strongmarket, but if the market is lowand fruit dumped accordingly, thepigs provide a service in cleaningup fruit dumps which wouldotherwise harbour fruit flies.

• Aboriginal people recognise thecultural value of pigs but they alsoacknowledge they can damagesome native bush resources.

Striking a balanceWhat is needed is an understandingof the relationship between differentlevels of reduction in pig abundanceand the magnitude of the economicand environmental benefits gained.Clearly there is a threshold populationsize above which they do significantharm, but below which their impactcan be tolerated and their servicesenjoyed. Understanding the level ofthis threshold, and evaluating the costof holding the pig population below itcan only be achieved by large-scaleexperiments in population controlwithin an adaptable managementframework.

Certainly, given the impossible task oferadicating pigs completely - we mustlearn to live with them.

Further InformationThe Rainforest CRC has published theproceedings from a Feral Pig Work-shop held in Cairns in March 1999. Thepublication addresses the feral pigissues in the Wet Tropics in detail. Toobtain copies contact:Rainforest CRCPO Box 6811, Cairns QLD 4870Phone: (07) 4042 1246Fax: (07) 4042 1247Email: rainforestcrc@jcu.edu.au

The ecological damage of pigs tends to be

highly concentrated in certain micro-habitats

like the fringes of swamps and wetlands

(photographs: Jim Mitchell)

Pig trapped by the community based feral

pig trapping program; around 2000 pigs are

killed annually under this scheme.