Date: 14 March 2012
A joint National Institute of Water & Atmospheric Research (NIWA), Department of Conservation (DOC) and Auckland University research team is returning to continue their research on Stewart Island’s / Rakiura enigmatic white shark population.
The research will be conducted from the DOC vessel Hananui from 16 - 28 March 2012 around the Titi Islands located off Stewart Island's northeast coast and Ruapuke Island in Foveaux Strait as weather permits.
White shark known as Grim (2.8 m long), Herekopare Island/Te Marama, 28 March 2011Divers and kayakers are advised to avoid the areas where the research is being conducted while the boat is on station and for at least 24 hours afterward as the team will be using berley (a mixture of minced fish and fish oil) to attract sharks.
“Fragments of berley may settle to the bottom and continue to hold a shark or sharks at the site for several hours after berleying has ceased,” says DOC shark expert Clinton Duffy.
The principal study sites for this trip will be Bench, Edwards and Ruapuke Islands.The research team will shift between these islands and other sites depending on weather conditions and the presence or absence of sharks.
“We will relay the location of the study vessel daily via local fishermen’s radio, to alert any divers or kayakers,” says Mr Duffy. “This information will be updated each time the vessel shifts site.”
The waters around Stewart Island have long been recognised as a hot spot for white sharks in New Zealand. This is the sixth year the team has travelled south to undertake photo-identification and tagging in an attempt to learn more about this now protected species.
Last year a total of 41 individual sharks were photo-identified around Bench, Edwards and Ruapuke Islands, including 18 that had been previously sighted in 2010. This included two large females that the team has seen every year since 2008, and a juvenile male nicknamed ‘Grim’ that was satellite tagged near the Bunkers Islets in March 2010.
In 2010 Grim undertook a much publicised migration from Stewart Island to Fiji. Last year he returned to the Pacific Islands but this time he visited Tonga. His tag appears to have stopped transmitting but he has been re-sighted several times already this year at Edwards Island. In contrast one of the large females, made two return trips to the Auckland Islands from Stewart Island before migrating to the same seamount in the Coral Sea that she visited in 2010.
"The research team has also been collecting data from acoustically tagged sharks using an array of listening devices deployed around north-eastern Stewart Island and Ruapuke Island for the last year," says NIWA Principal Scientist, Malcolm Francis.
"Data collected so far confirms that most white sharks depart from this region in winter as they undertake long-distance migrations to the tropic. 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 the forthcoming trip will hopefully show whether and when the other sharks have returned. We will also find out how long each shark spends in each location, and how mobile or residential they are," Dr Francis adds.
- White Sharks, also known as the great white or white pointer, became a fully protected species under the Wildlife Act from 1 April 2007.
- It is illegal to hunt, kill or harm a white shark within New Zealand’s Exclusive Economic Zone.
- It is also illegal in New Zealand to possess or trade in any part of a white shark.