Great white sharks swim away from beaches after being tagged, a drumline trial reveals
A SIX month trial of “smart” drumlines at popular tourist beaches has shown great white sharks that are hooked are not hanging around after they are released.
NSW
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ONE great white shark is being caught every two days during a trial of smart drumlines on popular NSW beaches.
And researchers are discovering the drumlines may be making swimming and surfing safer in an unexpected way as the captured sharks move into deeper water after being tagged and released.
As part of a State Government trial, 20 smart drumlines were placed between Forster-Tuncurry and Coffs Harbour-Sawtell on the mid-north coast and north coast about six months ago.
In five months they caught 80 white sharks of up to four metres long — an average of one shark every two days.
Sixty four sharks were caught, tagged and released at Forster and 16 at Coffs Harbour. Nine tiger sharks were caught at Coffs Harbour.
The mid-north coast smart drumlines are among 100 drumlines — which send a signal to researchers when a shark takes the baited hook under a float — which have been deployed since 2015 in the trial at key beaches from the North Coast to Kiama.
Captured sharks are fitted with an electronic tag and then released a kilometre off the beach and tracked by a series of receivers.
Department of Fisheries Research director Natalie Moltschaniwskyj said preliminary results of the trial, to be released today, showed most sharks were swimming away from the beaches where they were caught.
The tagged great whites — mostly juveniles and sub-adults — were staying in deeper offshore waters for up to four weeks.
The sharks then rejoined their counterparts in their movements north from Tasmania and Victoria during April and May before heading back south by January.
“The main story is that the animals are moving away from us for between two and four weeks,” Ms Moltschaniwskyj said.
“The other thing we are fairly confident about now is that there is no such thing as a resident shark that hangs out, stalking everything at a beach.
“They may hang around for a day or so, but then they move on. That’s an important finding. Ultimately, what we are hoping for is to have enough data to be able to know where and when they are around, so we can put together a picture as to when to expect a shark in your general area.”
She said there had only been a few instances where an already tagged sharked was caught a second time.
No bull sharks were caught on the mid north coast drumlines with the result attributed to the species mostly feeding at night when the lines weren’t baited.
Another 20 smart drum lines have been put in place at Kiama-Shell Cove, and Ulladulla-Narrawallee on the south coast.
NSW Primary Industries Minister Niall Blair said the research would be analysed to determine the future use of smart drumline technology to keep beaches safe.