Warmer sea temperatures could be the reason for earlier than usual shark sightings.

Mt Maunganui beach was closed yesterday and hundreds of swimmers were forced to flee the water after one had a close encounter with a shark.

Department of Conservation shark expert Clinton Duffy says it's not just the Bay of Plenty where sharks gather, but Manukau, Kaipara and Waitemata Harbours also have sharks at this time of the year. However, he says the animals are not as much of a problem as they are across the Tasman.

"We're not likely to see shark attack statistics as they see in Australia. We've had about two bites each summer on average for the last 20 years and they usually just result in just minor injuries to hands and feet."

Mr Duffey says in Australia, there are a large number of different shark species, in reasonable numbers.