Kaikoura schoolboy Harrison Mumford, 12, poses with a 1.93-metre female porbeagle which washed up on the main beach at Kaikoura.

A shark washed up on the main beach at Kaikoura has been correctly identified as a porbeagle, a shark species closely related to the great white.

The 1.93-metre long female was found by children below the high tide mark on Tuesday night.

It was initially thought to be a great white.

Christchurch based fisheries researcher Peter Langlands said porbeagle sharks were closely related to great whites and mako sharks.

"The porbeagle shark comes from the mackerel shark family closely related to great whites but smaller and feeds on squid and hoki," he said.

"There are four types of mackerel shark - great white, mako, porbeagle, and salmon shark which are found in the northern hemisphere."

Langlands said the porbeagle's teeth are smaller than the great white's and the eye is more forward on the head than its bigger relative.

The dark colouring on the pectoral fins also set it apart from the great white and mako, he said.

Porbeagle are often caught in large numbers as by - catches by commercial fishing boats working in deep water off the East Coast, he said.

"They can grow up to three metres long and weigh up to 300 kilograms."

Langlands said the shark washed up may be a young adult which had been a by - catch and thrown back into the sea.

"There is not a big market for them."

Porbeagles are not a known threat to swimmers as they often live in over 100 metre deep waters.

"Very little is known of them and the population has almost collapsed in Europe due to over fishing."

Kaikoura resident Brett Mumford said he took his family down to the beach to see the shark about 9pm.

"My son got a text from a friend it was down there so we all went down to have a look."

The family later dragged the shark back off the main beach into scrub.

Department of Conservation worker Mike Morrissey initially believed the shark to be a great white.

He measured it at 1.93 metres, and estimated it weighed about 150 kilograms.

"It is not common to get them washed up here. We normally see a few bigger ones now and then in the sea swimming the seal colony around Ohau Point."

The shark did not have any injury marks and it was not obvious how it died, he said.

The head was cut from the body and will be sent to DOC research staff for analysis, Morrissey said.

The body will be disposed of.

"It won't be wasted, I might use some of the body for my stoat traps," he said.

An elephant seal which came ashore to rest at Goose Bay, south of the Kaikoura, returned to the sea last week.