Satellite tracks shark on 12,000-mile swim

WASHINGTON — A great white shark named Nicole logged more than 12,000 miles swimming from Africa to Australia and back, the first proof of a link between the two continents' shark populations, researchers say.

A second report details the movement of dozens of salmon sharks from summer waters near Alaska to warmer winter quarters off Hawaii and Baja California.

"Sharks have home ranges that are at the scale of ocean basins," said researcher Barbara Block of Stanford University. She said conservation management of sharks such as the white shark and salmon shark will require international cooperation.

Tracking a shark from Africa to Australia "is one of the most-significant discoveries about white-shark ecology and suggests we might have to rewrite the life history of this powerful fish," said Ramon Bonfil, lead author of that study.

Both reports appear in the current issue of the journal Science.

George Burgess, a shark expert at the Florida Museum of Natural History, said that while sharks are known to travel long distances, this was the first evidence of movement between Australia and Africa.

Enric Cortes of the National Oceanic and Atmospheric Administration's Shark Population Assessment Group in Panama City, Fla., agreed this is the first direct evidence of a connection between African and Australian white sharks.

Using satellites to track sharks may provide new perspective on their movements, he said. Wildlife Computers of Redmond made the tracking devices.

A satellite tracking device temporarily attached to Nicole, named after actress Nicole Kidman, documented her 99-day swim from South Africa to Australia. About six months later, she was identified from photos back off the coast of South Africa.

Twenty-four other white sharks tagged off South Africa engaged in wide-ranging coastal migration, but only Nicole headed out to sea. Nonetheless, Bonfil said, "I don't think we got one in a million."

In the other study, Block's group tagged 48 salmon sharks in Alaskan coastal waters and tracked them by satellite from 2002 to 2004.

They found some sharks remained in the North Pacific all year, while others swam south to Hawaii or Baja California in winter. As they swam south, they dived deeper into cooler waters, the researchers found.

"The shark heart slows down in the cold, just as our own heart would," Block said. "But ... where our heart would simply stop, the salmon shark keeps on ticking."

Material from Bloomberg Business News is included in this report.