Authorities in northern Western Australia are warning amateur boaties they are risking their lives by attempting to swim with humpback whales off the Ningaloo Coast.

The coastal town of Exmouth is in its second year of commercial humpback whale swimming trials, but the trials seem to have prompted some people to try to approach humpback whales in dinghies and on jet skis instead of with accredited operators.

WA Parks and Wildlife Service Exmouth whale conservation officer Dani Rob said, so far, only boats had been damaged, but it was only a matter of time before a swimmer was hurt.

"It's a dangerous activity and it does certainly feel like someone is going to be badly injured — or worse — by trying to have a swim with these animals," Ms Rob said.

'Like approaching a herd of elephants': tour operator

Up close and personal with a humpback whale in Ningaloo Marine Park. ( Supplied: Eco Ocean Adventures )

Ocean Eco Adventures owner James Small said he had seen people harassing humpback whales "quite a bit".

"I think now that we're doing it commercially, people feel that they've got the right to go and hop in with the whales whenever they want," he said.

"People don't really seem to give humpback whales enough credit for their sheer size.

"We're talking about an animal that's 40 tonnes and people are pretty blasé about getting in with them."



Mr Small said licensed operators had completed humpback whale interaction training to learn how to identify signs whales were distressed or could become aggressive when protecting their calves.

"It's kind of like approaching a herd of elephants," he said.

"If you've never had anything to do with approaching elephants then it's a pretty dangerous place to put yourself in.

"It's no different for humpback whales but I think just because they're out in the water and everyone has access to them … they seem to forget that risk is always present.

"It's a really safe and amazing experience if done with trained commercial operators but it has the potential to be dangerous if uneducated people do it on their own boats."

Mr Small said signs at local boat ramps would help educate people who may be unaware they were breaking the law and risking their lives approaching whales.

DIY tours stress out mothers and their calves

A humpback whale breaches along the Ningaloo Coast of Western Australia. ( Supplied: Dani Rob/WA Department of Biodiversity, Conservation & Attractions )

In WA, only operators with vessels licensed by the department can run commercial whale-watching tours.

Private vessels, including jet skis and kayaks, do not require licences but must follow whale-watching guidelines.

They include keeping a 100-metre distance and not swimming with, feeding, or touching whales.

Ms Rob said the Exmouth Gulf was the most significant resting ground for female humpbacks and their calves in the Southern Hemisphere, during their journey from birthing grounds in the Kimberley to feeding grounds in Antarctica.

"It's a really important stage in their migration and it's crucial to their long-term survival," she said.

"These animals need to be in peak physical condition to be able to get all the way back down to Antarctica.

"If they are being continually disturbed by people trying to swim with them or manoeuvring their boats in an unfriendly way it's … going to impact on these animals."

The department will review the humpback whale swimming trial in the coming months to determine if it will continue next year.