QPWS, 2007:

"The aim of the survey was to obtain indicators of population trends by determining the current distribution and abundance (by size class), of estuarine crocodiles in a representative sample of waterways around Queensland’s populated east coast. This is to determine whether a population ‘explosion’ is taking place. The survey did not set out to estimate the total population of estuarine crocodiles in Queensland. This would have required a far more extensive survey over a much longer period. This survey was designed to provide indicative information as to the status of estuarine crocodile populations in populated areas so as to respond to public concern in a timely manner. A total of 47 major waterways were surveyed along the populated east coast of Queensland in an area stretching from the Endeavour River near Cooktown to the Burnett River near Bundaberg. Waterways surveyed were selected based on proximity to urban centres and waterways where previous surveys had been conducted to enable comparisons to be made. These selection criteria precluded the need to survey all waterways in the area and allowed effort to be focused in such a way as to maximise the return on the time and resources invested.

The results of this survey do not support the claim that estuarine crocodile populations are ‘exploding’ and show no discernable increase in estuarine crocodile populations between 1999 and 2007. The evidence suggests that no range expansion has occurred as no estuarine crocodiles were sighted south of the Fitzroy. Estuarine  crocodiles are a long-lived species with high rate of juvenile mortality. If its environment was unaffected by human influences, you would expect the population to be dominated by adult animals with very low numbers of juveniles (Cott, 1961; Graham 1968). The strong population bias towards hatchling and sub-adult animals and the low level of mean relative abundance found in this survey suggests Queensland’s estuarine crocodile population is still in a recovery phase. The findings of this survey (in relation to mean relative abundance and size class distribution) are consistent with the results from previous research conducted over the last 30 years that has shown Queensland’s estuarine crocodile populations are recovering slowly. This slow rate of recovery is likely to be attributable to ongoing modification of suitable nesting habitat from urban development, the QPWS’ ongoing removal of problem crocodiles (usually large crocodiles of breeding age), feral depredation of nests, intensive agriculture activities, the slow maturation rates of estuarine crocodiles and the low numbers of hatchlings that reach breeding age."

---

Citation and/or URL

Distribution and abundance of the estuarine crocodile (Crocodylus porosus Schneider, 1801) in waterways of Queensland's populated east coast.  Report to Hon. Lindy Nelson-Carr MP, Minister for the Environment and Multiculturalism.  Queensland Parks and Wildlife Service 2007.

Spatial Coverage

Waterways between Gladstone and Cooktown

Temporal Coverage

2007

Update Frequency

Not applicable 

Other Information

None