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2009-2010 Survey of estuarine crocodiles in Queensland waterways

A representative sample of waterways between Cooktown and Maryborough was surveyed for the presence of estuarine crocodiles (Crocodylus porosus) between September 2009 and February 2010.

The aim of the surveys was to:

  1. give a representative snap-shot of the current crocodile distribution and abundance
  2. provide data against which future survey data can be measured.

All surveys were conducted using agency vessels adopting standard spotlight survey methodology by trained departmental staff, and a total of 48 representative rivers and creeks were surveyed within the study area, encompassing 735 kilometres of waterway.

The mean relative density of non-hatchling C. porosus recorded during these surveys was only 0.49 ± 0.72 non-hatchlings/km (mean ± standard deviation). These results are consistent with previous survey data and do not support a hypotheses that C. porosus is experiencing a significant increase or ‘population boom’ in waterways of the populated east coast of Queensland.

A total of 293 crocodiles were sighted, ranging in size from 0.3 m to 3.8 m in length.

Of the 293 crocodiles sighted, 258 of the animals were estuarine crocodiles (C. porosus) and 35 of the animals were freshwater crocodiles (C. johnstoni).

The population was strongly biased towards immature animals with 73 per cent of all C. porosus sighted (for which a total length could be estimated) being equal to or less than 2.0 m in total length. The population bias is indicative of a recovering population.

No crocodiles or evidence of crocodiles were sighted in any of the waterways surveyed between the Fitzroy River and the Mary River south of Bundaberg. Although incidental sightings are reported south of the Fitzroy River, these data do not indicate any southern drift in species distribution.

Hatchlings were recorded in 37 per cent of waterways surveyed within the accepted range of C. porosus, indicating there is some successful nesting occurring throughout the study area.

All of the crocodiles were recorded in known crocodile habitat and none of the recorded crocodiles exhibited behaviour indicative of a crocodile of concern.

  • Report on the distribution and abundance of the estuarine crocodile, Crocodylus porosus, in Queensland. Waterways of the populated east coast area Research conducted September 2009 to February 2010(see availability)

Available from the library catalogue

The documents referred to on this page are available from the department’s online library catalogue.

Last reviewed
14 September 2016
Last updated
6 June 2011