KEY POINTS:
One of three electronic transponders so far discarded near Tonga by great white sharks tagged at the Chatham Islands has been recovered from the Ha'ateiho Reef.
Roger Miller and Bruce Dixson, from Waste Management Ltd's Nuku'alofa office, found the $5200 tag at the co-ordinates it transmitted.
Mr Miller lives about 1.5km from the beach but was unable to find the tag before it stopped transmitting on November 7, the Matangi Tonga newspaper reported.
On Tuesday night, the tag transmitted briefly again and Department of Conservation scientist Clinton Duffy in Auckland was able to send the new co-ordinates.
"We were able to track it by GPS to within 20m of its location and then we saw it lying on the reef," said Mr Miller. "It was slowly moving down the coastline."
There was no reward for the recovery but Mr Miller said Air NZ's Nuku'alofa agent had offered to carry the tag back to Auckland free of charge.
The data it contains will be analysed by New Zealand marine scientists to trace the shark's diving behaviour and temperature preferences, and a record of light levels to roughly estimate the path it travelled.
The information may provide clues to why the sharks are travelling to Tonga, when local fisheries archives show no record of the species there.
Six great white sharks were tagged in the Chathams in April and, so far, three tags have surfaced in Tonga, but this is the only one to be recovered.
The researchers said the tags appeared to have detached prematurely, and they hope two tags thought to still be attached will stay on until January to see if those sharks return to New Zealand waters.
- NZPA
