A seventh whale has been found beached on Yorke Peninsula in South Australia near where six sperm whales died after becoming stranded at low tide.

Six of the stranded whales were found on a beach in Ardrossan Monday morning, while the seventh whale was found near a jetty later in the day.

A fisherman has also reported seeing an eighth whale in deeper water.

Ardrossan caravan park manager Steve Ruddock said a worker at his park spotted some of the stranded whales splashing in the water as the tide headed out this morning.

"Because they are so fresh, there's no smell, but it won't be long until they get on the nose, I'd say," he said.

Mr Ruddock and his son, Josh, measured one of the whales to be about 13 metres long.

"There's three that are about that size, and the other three are a fraction smaller," he said.

Mr Ruddock said the water at Ardrossan was very shallow and he had never seen anything like it in the area.

"We talked to a lot of the locals and there's been the odd sighting now and then on the sea, but this is very unusual," Mr Ruddock said.

Locals investigate a dead sperm whale at low tide. ( Audience submitted: Steve Ruddock )

John, who lives nearby, said the pod was spotted in the area on Sunday night and became beached after chasing fish.

"When the tide was up they were chasing a school of salmon," he said.

A beached whale on the shore near Ardrossan. ( Twitter: @Brad_Aldridge )

"It looks like the school of salmon came in too close and the whales were beached while chasing them."

South Australian Museum senior research scientist Cath Kemper said museum and national parks staff were at the scene.

"In all my 30-something years in the museum, we've never had a group of sperm whales come up," she said.

Ms Kemper said there was was little hope of saving the whales once they had become beached.

"There was one that was still moving a little bit this morning but with animals this size they just don't survive," she said.

"Putting them back in the water is no good because once they're high and dry they start doing lots of damage to their insides.

"I suspect something has happened out beyond the Gulfs, in the bigger ocean south of South Australia and it is led either one or more of them to make a mistake, or something is wrong with it, and because they have such amazing social cohesion, so they stick together as a group.

"If one is in trouble and they come into shore, the rest of them follow."

Locals check out a pod of beached whales near Ardrossan. ( Audience submitted: Steve Ruddock )

Ms Kemper will lead a team of researchers to the site on Wednesday to take samples.

After that negotiations between the museum, local council and Department of Environment, Water and Natural Resources will begin to arrange a clean up of the carcasses.