University of Technology, Sydney


Trigger points

The Murray Darling Report (Hacker et al. 2004) examined the sustainability of kangaroo harvesting from the perspectives of stakeholders including farmers, the kangaroo industry, and conservation groups. The report identified a quasi-extinction density of five kangaroos per km2 below which kangaroo harvesting becomes both commercially unviable and ecologically risky. Harvesting affected population modelling indicates that where harvesting strategies depress kangaroo densities below the quasi extinction there is an elevated risk of population densities reaching two kangaroos per km2, a minimum population density level below which Eastern and Western Grey Kangaroo and Red Kangaroo populations are considered at risk of extinction (Hacker et al. 2004).

These values are important because an independent literature review prepared for the Federal Kangaroo Management Advisory Panel (Olsen and Low 2006) confirmed the conclusions of the Murray Darling Report (Hacker et al. 2004). The review states the rather obvious: that commercial harvesting is not sustainable at densities that threaten any of the harvested species with extinction (Olsen and Low 2006). The data in Table 1 raises concern because of the many commercial harvesting zones where populations have dropped to either the extinction risk or quasi extinction densities.
An oft used argument is that kangaroos will migrate from one management zone to another (Pople pers. comm. in Grigg G (2002)). However, the term ‘management zone’ belies the size, which can by that of a European country. Red Kangaroos, the most mobile of the harvested kangaroos, are relatively sedentary (Croft 1991; Moss 1995). In response to concern about diminishing kangaroo populations in NSW an Administrative Appeals Tribunal forced the inclusion of density trigger points for the four harvested species below which harvesting will be cease (Administrative Appeals Tribunal 2008). Other states are yet to adapt such sensible regulatory measures.
Administrative Appeals Tribunal (2008). Decisions and Reasons for Decision re WIldlife Protection Association of Australia Inc. (Applicant) and Minister of the Environment, Heritage and the Arts (Respondent). Report AATA 717.

Croft, D. B. (1991). "Home range of the red kangaroo Macropus rufus." Journal of Arid Environments 20: 83-98.

Hacker, R., S. McLeod, J. Druhan, B. Tenhumberg and U. Pradhan (2004). Kangaroo Management Options In The Murray-Darling Basin. Canberra, Murray Darling Basin Commission.

Lundie-Jenkins, G. (2008). Macropod Harvesting and Population Data, Queensland Environment Protection Agency Macropod Management Unit.

Moss, G. L. (1995). Home range, grouping patterns and the mating system of the red kangaroo (macropus rufus) in the arid zone. Sydney, University of New South Wales.

Olsen, P. and T. Low (2006). Update on Current State of Scientific Knowledge on Kangaroos in the Environment, Including Ecological and Economic Impact and Effect of Culling, Kangaroo Management Advisory Panel.

Payne, N. (2007). 2008 Kangaroo Quota Report New South Wales NSW Department Environment and Conservation, North West Branch.

Pople pers. comm. in Grigg G (2002) Conservation benefit from harvesting kangaroos: status report at the start of a new millennium: A paper to stimulate discussion and research. A Zoological Revolution. Using native fauna to assist in its own survival. D. Lunney and C. Dickman. Mosman, Royal Zoological Society of NSW: 53-76.

Sutterby, N. (2008). Decimation of an Icon, Australian Society for Kangaroos.

Thomsen, D. (2008). South Australia’s kangaroo populations and ‘harvest’ statistical data, Kangaroo Management, Dept Environment and Heritage.