SHARKS that have "attacked" small boats on the North Coast recently are unlikely to have done so deliberately, a professional fisherman has said.
And University of Newcastle shark expert Dr David Powter said the magnetic field emitted by a tinny was similar to the field emitted by the living creatures sharks like to eat.
Kingscliff resident Daniel Fleming yesterday said he believed his boat had been attacked by the same shark twice within six months and Byron Bay fisherman Robbie Graham was knocked into the water less than a fortnight ago when a white pointer charged his tinny.
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Dr Powter, a University of Newcastle lecturer in environmental science, said the shark that attacked Mr Fleming's boat was a great white.
Dr Powter said sharks were usually attracted to fishing boats by blood in the water and weakened fish.
However, there is another reason why they can tend, on occasions, to attack small boats.
"Sharks have an electro sense with which they detect the weak magnetic fields living things produce, an electric field which is replicated by an aluminium boat," Dr Powter said.
"It's not uncommon they would explore objects because of that sensory information they are receiving."
"A lot of it has to do with whatever is in the water at the time, it's getting a whole of information and then naturally responding to that sensory information."
News of Mr Fleming's and Mr Graham's run-ins follows a run of shark incidents and attacks on the Northern Rivers.
- On February 9, popular local surfer Tadashi Nakahara was killed by a great white while surfing at Shelly Beach.
- A Day earlier, on February 8, Jabez Reitman was bitten on the back while surfing at Seven Mile Beach
- On January 26, Hamish Murray was thrown about a metre into the air when what was believed to be a shark hit his board while he was surfing at Flat Rock
- A few days earlier Yamba's Dianne Ellis had her board snapped by what was believed to be a shark while surfing at Wategos.
- In September last year, Byron Bay man Paul Wilcox was killed by a great white while swimming at Clarkes Beach
Byron part-time professional fisherman Mark Stewart, who had his own face-to-face encounter with a great white at Cape York a few years ago, said such incidents were usually accidental and a result of a shark going into a "frenzy" while chasing fish.
"They're not trying to knock the person out of the boat to eat them," Mr Stewart said.
Several years ago during a fishing expedition off the tip of Cape York a shark - believed to be a tiger shark - charged his friend's boat and bit the propeller.
"It bent the blades so we couldn't get into gear… we had to get towed back to the beach and get the propeller fixed," he said.
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"It happens quite often."
Mr Stewart added that this year was an exceptionally "bad year" for shark numbers, with a steady stream of sightings, reports of line fisherman losing their catch, and the tragic fatal attack on Tadashi Nakahara last month.
"We've got a lot of pelagic species moving through with the warm water, this year we've had exceptionally warm water, it's one of the longest spells of warm water I can remember. That
"There's more sharks this year than this area has ever seen."
Last week Ballina Shire Council held a meeting with shark experts and Tweed Shire Council (Byron Shire Council was invited but chose not to attend) to discuss technologies to make beaches safer, including aerial patrols and sonar detection.