White shark headed south
Australian marine biologists are again tracking the movements of a white shark off the south-east of the country as part of an ongoing project to understand the behaviour of the species.
Nicknamed Neale after local commercial fisher Neale Blunden who assisted in its capture, the 2.4 metre juvenile male shark has travelled more than 850 kilometres since being tagged by CSIRO scientists Dr John Stevens and Barry Bruce on March 2nd.
"Satellite tracking opens up a window on the private lives of sharks," Barry Bruce told ABC Science Online. "We get information as it happens".
Twelve months ago, the same research team tagged a juvenile female shark they called Heather. However the researchers lost contact with the shark after 46 days - they believe Heather damaged the transmitter aerial.
"This time we've made the tag more robust and so far we have been able to track Neale for 68 days," said Mr Bruce.
Based on signals received every 2 to 3 days the researchers discovered that, like Heather, Neale spent several weeks swimming up and down a 75 kilometre section of the Victorian coast at an average distance of 15 kilometres from shore.
"We've confirmed, that like Heather, Neale was resident in the area for several weeks to feed on the large numbers of snapper that were around at the time," said Mr Bruce.
"We've also confirmed what local fishers say - that when the snapper move away, the white sharks disappear. But the question is where to?".
Unlike Heather who headed north after gorging on the snapper, the researchers found that Neale headed in a different direction, and is now heading down the east coast of Tasmania.
After heading north along the Victorian coast on April 19th at an average speed of three kilometres per hour and five to six kilometres from shore, he moved offshore and turned south, across Bass Strait to reach northern Tasmanian waters on 26th April.
"The sharks are obviously attracted by food but what we don't know is how they navigate," said Mr Bruce.
Barring damage to the 20cm long tag, or accidental capture of Neale, the scientists hope the project will enable them to follow Neale's daily and seasonal movement patterns for up to a year.
The scientists hope the tracking project will also provide some insight into whether white shark populations in various parts of Australia are linked.
White sharks are threatened species and the research aims to improve understanding of their behaviour to both inform the public and assist in their conservation.
The research project is funded under the Natural Heritage Trust through Environment Australia's Marine Species Protection Program and has received assistance from the Discovery Channel and the Melbourne Aquarium.