In brief: Tracking pilgrim’s progress
NIWA researchers head to Foveaux Strait this month to look up an old friend. 'Grim', a young male white shark, made headlines in 2010 when satellites followed his epic swim from Stewart Island to Fiji.
The transmitter he carried has since fallen silent, but NIWA Principal Scientist, Dr Malcolm Francis, says Grim has been spotted back at Edwards Island, the largest of the Titi Islands in Foveaux Strait, this year.
For the sixth consecutive year, a joint NIWA, Department of Conservation and Auckland University research team will tag and photograph sharks off Bench, Edwards and Ruapuke Islands in a bid to learn more about this enigmatic, now-protected species.
The waters around Stewart Island are a favourite haunt of white sharks. Last year, the team photographed 41 individuals, 18 of which had been previously sighted in 2010. Researchers have encountered two returning visitors – large females – every year since 2008, one of whom made two return trips to the Auckland Islands last year before setting off for the same seamount in the Coral Sea she visited in 2010.
Then, of course, there's Grim, who was satellite-tagged near the Bunkers Islets in March 2010.
The team has also been listening in on acoustically-tagged sharks around northeastern Stewart Island and Ruapuke Island, says Francis, using electronic buoys which record the unique sound emitted by each shark's tag. "We know which shark has swum past which buoy," says Francis.
"Data collected so far confirm that most white sharks depart from this region in winter, as they undertake long-distance migrations to the tropics.A data download in late January showed that at least four of the sharks tagged in March 2011 had returned to the region."
Another download on this trip should reveal which sharks have returned. "We'll also find out how long each shark spends in each location, and how mobile or residential they are," he says.