Research & Initiatives
The State Government is supporting a variety of research projects and initiatives to gain a better understanding of shark biology and ecology by implementing (and investigating) various public safety initiatives and making changes to government policy. The aim is to provide everyone with useful information to make informed decisions about their water use.
Shark Monitoring Network06 November 2013
The Shark Monitoring Network is providing vital public safety warnings that may help save Western Australian lives.
The project began in 2009, to see if it was possible to monitor movements of tagged white sharks off Perth and to use new satellite-linked technology as an early warning system when they swam close to popular beaches.
In the project’s feasibility phase, over 80 sharks were fitted with acoustic transmitters or ‘tags’ in South and Western Australia. Since white sharks are difficult to find and travel long distances across State borders, the ‘tagging’ element of the project relies on close collaboration between scientists from the WA Department of Fisheries’ Shark Research Section, the CSIRO’s Wealth from Oceans Flagship and the South Australian cage-diving industry.
Each tag emits a sequence of low frequency ‘clicks’ that give each tag an audible ID number. These unique signals can be detected and recorded when the shark swims within 400-500m of an acoustic receiver.
Acoustic receivers were deployed off the Perth metropolitan coast to monitor the movements of tagged sharks. The initial project involved the deployment of 20 satellite-linked (VR4G) acoustic receivers, and a further 19 data-recording acoustic receivers (VR2W) on the sea floor. Detections by VR2W receivers are not transmitted via satellite but are stored in the receiver’s on-board memory. The ID number, date and time of each detection are recorded by the receiver.
The project was given a major boost when the international Ocean Tracking Network project installed 53 data-recording acoustic receivers between the shore and 200m of water 25km west of Rottnest Island. This line of receivers is installed at 800m intervals, so that under most conditions they provide a continuous line of detection.
In the three years until the end of 2011, ten tagged white sharks had been monitored off the Perth coast over 56 days. These sharks triggered nine real-time alerts by the satellite-linked receivers.
Based on successful feasibility trials off Perth metropolitan beaches between 2009 and 2011, the Government committed additional funds (of $2.5 million) to extend the life of the project until July 2015 and expand its geographic coverage.
The expanded network includes an additional 125 data-recording (VR2W) receivers installed in three lines off Hamelin Bay, Chatham Island and Bald Island which extend from the shore across the continental shelf to about 200m in depth. Like the complementary Ocean Tracking Network line off Perth, these receivers are placed 800m apart.
For the summer of 2013/14, the expanded network includes five additional satellite-linked (VR4G) receivers around the southwest to provide real-time alerts of tagged sharks’ detections between Bunbury and Albany.
The project has grown to include other potentially hazardous shark species, including tiger, dusky and bronze whaler sharks.
The aims of these expanded monitoring capabilities are to provide:
- A more accurate understanding of white sharks’ large-scale movements from South Australia into the southwest and lower west coast regions of WA.
- Data to examine what environmental conditions contribute to the apparently fluctuating abundance of white sharks off the lower west and southwest coasts of WA.
- Evidence of whether individual sharks repeatedly visit particular locations and whether sharks tagged in the area are residential or non-residential in those areas, and
- A system for alerting public safety officials and the public about tagged sharks' movements close to populated areas, beaches and surf breaks in Perth and the southwest.
The Shark Monitoring Network provides an unique opportunity to collect long-term data about white shark movements around the most populated parts of the State. With a better understanding of when, where and why these species travel into these areas, we hope to develop more effective shark hazard mitigation strategies.
To view current receiver locations and explore the data collected, visit our Shark Monitoring Network Research Map.
Collecting the detection data is only part of the job and all receivers need to be annually serviced. Satellite-linked (VR4G) receivers need fresh batteries and a major service of their buoys and moorings. Data-recording (VR2W) receivers need to be recovered annually by divers so that the stored data can be downloaded and receivers serviced. Most of the receivers west of Rottnest are too deep for divers to safely work with and instead are retrieved using electronic release mechanisms that allow them to float to the surface after being triggered from a boat above.