Satellite Tags Show How White Sharks Travel

The male sharks, which range in length from 3.2-3.8 metres and weigh 300-500 kilograms, travelled 500-700 kilometres in the first three weeks since being tagged.

They were tagged by a team led by CSIRO scientist Barry Bruce, from the 'Calypso Star', a charter boat owned and skippered by Rolf Czabayski.

"Managing the impact of human activities on white sharks in Australian waters is a complex challenge combining the interests of public safety, commercial and recreational fishing, tourism and conservation," Mr Bruce says.

"But information on the status and behaviour of white sharks in Australian waters is limited and often speculative. We're addressing this information gap on white sharks through research that examines their movement patterns, linkages between populations and favoured habitats, and their biological characteristics."

"The research is part of a broader program aimed at understanding the role of top order predators in coastal and open ocean marine ecosystems."

The tagging procedure involved capturing and temporarily holding the sharks in a cradle purpose-built by the Melbourne Aquarium.

The cradle was used for the first time in March this year to tag two white sharks in the same location. These sharks have since travelled a combined distance of more than 9000km, but the batteries in their tags are almost exhausted.

"Capturing white sharks for tagging requires careful planning and patience," Mr Bruce says.

"We select the shark, control where it will be hooked and then gradually tire it before bringing it into the cradle. It is all about managing their safety and our own."

The latest tagging success brings to 10 the number of white sharks fitted with satellite tags since March 2000 as part of CSIRO's ongoing research.

Mr Bruce says patterns are starting to emerge in relation to mixing between Australian regions, seasonal migrations and swimming behaviour.

"We now have evidence that white sharks move tremendous distances in Australian waters," he says. Sharks from South Australia seasonally travel as far as southern Queensland and north-west Western Australia.

"They seem to spend extended periods in one area when food resources are available, then make relatively rapid and directed movement away, presumably in response to food availability, or reproductive cues."

"Following several white sharks tagged at the same time provides us with a wonderful opportunity to see how coordinated their movements are and what cues they use to travel."

White sharks are protected in Australian waters under fisheries and threatened species legislation. CSIRO white shark research supports Australia's National White Shark Recovery Plan and National Plan of Action (sharks). It also helps Australia to meet international obligations under treaties including the Convention on International Trade in Endangered Species and the Convention on Migratory Species.

The white sharks have been named Rolf, Bomber, Michael and Sam C. Their tracks can be viewed on the web at http://www.marine.csiro.au