Kerri calls home
A 4.4 metre female great white shark has set a new distance record for a New Zealand shark by swimming over 3000km to the tropical waters of the southern Great Barrier Reef, Australia. The shark, nicknamed Kerri, has provided the first evidence that New Zealand great whites do in fact travel to Australia.
24 December 2007
A New Zealand–US team of scientists tagged Kerri with an electronic "popup" tag at Stewart Island in March. The tag records location, depth and temperature, and releases itself after a pre-determined time. The tag then floats to the surface, and transmits its data to a satellite, which emails the results to the scientists' computers.
The tag began calling home on Tuesday 18 December, making a welcome Christmas present for the scientists who have been waiting nine months to hear from Kerri. In about ten days, when all the data have been transmitted from the tag via satellite, the tag manufacturer will start decoding the data. “At this stage, we don't know what route Kerri took, or how quickly she travelled to Australia,” says NIWA fisheries scientist Dr Malcolm Francis. “In 2005, we discovered that New Zealand great whites can make deep dives, some to over 900 metres, during their migrations. We’re keen to get our hands on the depth and temperature data from Kerri’s tag to see her diving behaviour.”
Three great white sharks tagged at the Chatham Islands in 2005 all travelled north to subtropical or tropical waters. One went to New Caledonia, one to Vanuatu and the third to the Louisville Seamounts, northeast of New Zealand. Kerri set a distance record for a New Zealand shark, travelling over 3000 km to the Great Barrier Reef. Her tag popped up south of the Swain Reefs off Rockhampton, an area known to have been visited also by white sharks tagged in southern Australian waters.
White sharks were protected in New Zealand waters in April 2007, but we still know little about their habitat requirements, migratory behaviour and interactions with white sharks elsewhere. “Our tagging results show these sharks can be highly mobile, though they may also hang around seal colonies for several months at a time while feeding on seals. Australian tagged sharks have turned up in New Zealand waters; and now for the first time we have evidence that this is a two-way process. Our results suggest that white sharks in the south-west Pacific may comprise a single population” says DoC scientist Clinton Duffy.
This tagging programme has been a collaborative study carried out by scientists from NIWA, Department of Conservation, Shark-Tracker/NABU (Germany) and University of Washington (USA).