Treat all sharks with caution, warns scientist

Auckland-based marine scientist Clinton Duffy says a variety of sharks are common in Hawke's Bay during summer because of the warm weather.

Up to three shark sightings around Tauranga over the holiday period have sparked concern over what lurks beneath the surface of the Bay's most popular beaches.

Clinton Duffy, a marine scientist for the Department of Conservation, says there are a variety of sharks that frequent the Hawke's Bay sea in the summer months, many of which migrate here for the climate.

"Most of them are migratory, they come down following the warm weather. Some can go up as far north as the tropics in the winter but especially blue sharks and mako sharks are known for their love of clear, blue waters, that we get in Hawke's Bay in the summer."

Along with blue sharks and mako sharks, bronze whalers, hammerheads and sevengill sharks are all frequent visitors to the Bay.

"Bronze whalers breed in Hawke's Bay, generally up towards the mouth of the Mohaka River, but they come in closer too, to Westshore."

Mr Duffy, who lived in Hawke's Bay for six years before moving to Auckland, said often some of these species come in close to the shore to feed.

"Blue sharks go for fish closer to the bottom of the sea, which are normally closer to the shore. Bronze whalers like mullet fish, kahawai and stingrays, especially eagle rays, which are all found closer to the shore."

Also common in the summer months are smaller shark species including school sharks and spotted dog fish who stay closer to the shore.

"Some of the bigger sharks will eat those too."

He said any shark over 1.8 metres should be treated as potentially dangerous.

"With any shark, always retreat, treat it with caution. People need to keep an eye out for blue sharks, they have a tendency to randomly bite out at objects to see what they are."

* In December 1896, 36-year-old Bright Cooper died after being attacked by a shark off Marine Parade in Hawke's Bay's only known fatal shark attack.