Dozens of juvenile hammerhead sharks have washed up on a Coromandel beach.

At least 35 sharks have appeared, littering the shoreline at Ruamahunga Bay - an isolated spot on the Thames Coast Rd.

Cagn Anderson was undertaking road works on the coast road north of Waiomu on Thursday when he made the discovery.

CAGN ANDERSON At least 35 sharks have bee spotted on the shoreline at Ruamahunga Bay, on the Thames Coast Rd.

"There's a bank and you could see all of these sharks."

He took a video of the sharks and counted 36 scattered along the tidal line about 200 metres from the boat ramp.

High tide came and went and the sharks remained along the rocky foreshore on Friday.

SUPPLIED Cagn Anderson was working on the coast road north of Waiomuwhen he made the unusual discovery.

Some of the sharks reached around a metre in length, he said, while others appeared to be smaller juveniles.

A fisherman himself, Anderson suspects the sharks may have washed up after being dumped by a fishing outfit.

"It's isolated. You wouldn't be able to see them driving past."

supplied Some of the sharks reached around a metre in length.

Anderson had reported the discovery to the Department of Conservation.

A DOC spokesperson said that hammerhead sharks were not one of the shark species listed as protected under the Wildlife Act.

Sphyrna zygaena, otherwise known as the hammerhead shark, is typically found in New Zealand coastal waters up to 110m deep and more commonly found in the North Island.

The DOC spokesperson suggested that it may be a matter for the Ministry of Primary Industries under it's fishing responsibilities.

MPI is looking into the incident, she said.

Niwa principal scientist Dr Malcolm Francis said the dead sharks were most likely discarded by fishermen.

Judging by the photos and the eyewitness's description, the sharks were aged between six months and two years old, Francis said.

"Hammerheads hang around in shallow coastal waters like off Coromandel until they get big enough to leave. They're pretty vulnerable to set nets mostly but they're also caught by hook and line and trawls. They have no commercial value so if they were caught by fishermen they would probably discard them," he said.

Francis said it was uncommon for large numbers of hammerheads to wash up dead.

"Hammerheads are known worldwide as being easily stressed and they die easily once they're caught. It's something to do with the build-up of lactic acid in the body. Once they stop swimming, and stop getting water passing over their gills, they don't get enough oxygen to break down the lactic acid that builds up, so they get what's called acidosis which is a build-up of acid."