A large shark sighted in Mercury Bay could by now be anywhere along the coast, says Mercury Bay Game Fishing Club vice president John Neighbours.

This shark was photographed in Mercury Bay on Monday. Photo by Kane Hill.

The charter fisherman of 15 years says seeing a shark of that size in Mercury Bay is itself a rare event.

He didn't see the fish himself and is unsure of its size or species. It's been called a Great White, but the photo published locally showed a brown shark.

Fisherman Kane Hill photographed the shark in 6m deep water off the Hahei Marine Reserve on Monday. It was just a few metres away from an 8m glass bottomed boat.

'Great whites are not seen here very often that's for sure,” says John, 'and assuming the estimate of 4.5 metres is correct for the length of it, then that would be a bloody big bronze whaler. The chances are it might be a great white.

'As a charter fisherman here for 15 years and vice president of the game fishing club, I've never seen a great white here – and the huge majority of fishermen wouldn't have.

'In that photo it looks quite browny, which might lead you to suspect bronze whaler.

'Except that often photo colour can be deceiving, and it is very large if their estimate is correct. Without seeing it myself, I can't really comment.”

He says from Whitianga the shark will probably be moving south, following the warm water south like most migratory game fish do.

Surface water temperature in Mercury Bay over the weekend, even out in the game fishing grounds, was 20.3 Celsius. Yesterday after two days of rain it dropped to just over 18 degrees.

'It's not as cold as last year, but it's not really warm yet,” says John.

'Who knows where it is now. I haven't heard of any other sightings, so it could be anywhere.”

Department of Conservation shark expert Clinton Duffy says the shark was probably on its way back to summer feeding grounds around Stewart Island after spending winter in the tropics.