Shark that goes bump in the water

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SNAPPED: A blue shark photographed by Geraldine Meade at Tahunanui.

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Paul Baird's late-night fright in the water off Tahunanui Beach on Friday was most likely a blue shark checking him out, Conservation Department shark expert Clinton Duffy says.

Mr Baird was left bruised and rattled after being shunted by what he thought was a shark, and is now wary about swimming in the sea.

A shark photographed just off the beach in the Blind Channel last Tuesday night by Irish tourist Geraldine Meade has been confirmed by Mr Duffy as a blue shark, about 2.5 metres long.

Mr Baird said yesterday he felt "very, very lucky" nothing worse had happened. "I'm just counting my blessings."

He was swimming late on Friday night when something "very large" smacked into his side. He was in water up to his chest when he was suddenly hit and "pushed around like a toy".

"It really felt like I'd been hit by a small car," Mr Baird said.

Mr Duffy, who works at DOC's Aquatic and Threats Unit of DOC in Auckland, said it was "very typical" for blue sharks to investigate potential prey before they attacked.

"This definitely could be the culprit. They usually bump large potential prey several times before attempting to feed. They are usually easily dissuaded with a good thump, but if determined to feed they will become very persistent and eventually bite," Mr Duffy said.

He said the blue shark was not especially aggressive, but it grabbed and rolled its prey and left very clear bites.

Mr Duffy said blue sharks were in outer Tasman Bay all the time and had been seen lately in larger numbers circling the carcasses of pilot whales stranded off Farewell Spit.

"They are really only a risk to people drifting in the sea, but if it had bitten the man on Friday night, he could have been seriously injured."

Ms Meade spotted the shark in water near the Tahunanui camping ground where she was staying. Passerby Desiree Thiart said she also saw the shark in shallow water. "My dog was intrigued by the splashing and she jumped into the water."

Ms Thiart said she was "petrified" that the shark would attack the dog, but it took no notice and continued its eating frenzy.

Mr Duffy said the photos were "amazing", particularly because it was unusual to see a blue shark so close inshore.

It was a common ocean species, and regularly encountered at depths of between 20m to 100m in summer. It was unlikely the shark had set up a "territory", Mr Duffy said, which was a trait more common among shark species found around the shoreline.

Mr Duffy said it was likely the shark had already left the area, but people fishing in the channel should not throw fish remains into the sea, which was probably what attracted it.

"It's not going to linger – they're highly migratory animals which tend to move inshore at night and then head out again during the day."

SHARK FACTS

Blue Shark Size: Maximum 4-metres long, usually 3.35m. Where: Oceanic, but may be found close inshore. Usually found to a depth of at least 150m. Description: A slim, graceful blue shark with a long, conical snout, large eyes, and curved triangular upper teeth with saw edges. Diet: Feeds on fish (herring, silver hake, white hake, red hake, cod, haddock, pollock, mackerel, butterfish, sea raven and flounders), small sharks, squids, pelagic red crabs, cetacean carrion, occasional sea birds and garbage. Warning: Potentially dangerous to humans. Source: fishbase.org

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