Saltwater Crocodiles – Western Australian Marine Science Institution

Project

About the theme

Description

Saltwater crocodile populations have been protected in Australia since 1969 when three previous decades of unregulated hunting had driven down numbers across the Kimberley and the Northern Territory (NT) to less than 8000 individuals.

While annual surveys since 1975 in the NT have documented a spectacular recovery for the crocodile population, there has not been a similar sustained effort to monitor crocodiles in WA. While there have been regular surveys undertaken in the East Kimberley (Ord River), no surveys have been conducted in the west Kimberley since 1986.

This project studied the distribution, abundance, critical habitat and population growth rates of saltwater crocodile populations in the Kimberley region.

Aims

To count saltwater crocodiles in the Kimberley region;
To survey Kimberley waters that have never been surveyed for crocodiles in partnership with Indigenous Rangers e.g. Drysdale River and Walcott Inlet
To calculate population growth rates in river systems that have been surveyed previously
To study geographical variation in abundance and population growth rate between rivers systems
To identify critical habitat for saltwater crocodiles in the Kimberley region.

Methods

Boat-based, night-time spotlight surveys were used to record crocodile sightings and to estimate the size of individuals.
Tissue samples were collected using a purpose built biopsy pole to contribute to an Australia-wide study of crocodile genetic structure.

Outcomes

A baseline estimate of crocodile abundance in two important river systems in the west Kimberley.
Crocodile abundance has increased across the Kimberley since the last survey, 30 years ago, but not to the degree seen in the NT.
The crocodile population is maturing, evidenced by more sightings of large crocodiles (>1.8m)
Standard operating procedures for spotlight surveys as a method to monitor crocodile abundance and demographics undertaken by DBCA and Indigenous rangers.
A biopsy pole and methodology for obtaining genetic samples from crocodiles.
A database app for real-time input and storage of geo-referenced data collected during crocodile spotlight surveys.

Project News

Saltwater crocodile numbers up in the Kimberley, fears the reptiles will spread to populated areas

Saltwater crocodile populations continue to grow in Prince Regent River

Tide turning for Kimberley crocodiles

Kimberley crocodile numbers triple in biggest survey in three decades