A beachgoer discovered three dead melon-headed whales.
© Megan SpenceA beachgoer discovered three dead melon-headed whales.
West Australian wildlife authorities are investigating the deaths of at least three marine mammals found on a beach near Broome.

Three melon-headed whales were discovered lying on Mangalagun Crab Creek Beach, north-east of the tourist town, this morning by Broome resident Megan Spence, who regularly visits the area.

Her first thought was a shark or dolphin had washed ashore.

"It was very dark, almost black," Ms Spence said.

"Then I looked further up the beach and saw another one, then another 150 metres there was another.

"It was really sad."



The Department of Biodiversity, Conservation and Attractions (DBCA) responded to the grim find at the Yawuru Nagulagun Roebuck Bay Marine Park and collected scientific information from the dead mammals.

The melon-head whales have since been removed from the beach and disposed of.

More dead whales

Late this afternoon, a department spokesperson confirmed an aerial survey had located more dead melon-headed whales at the same beach.

The spokesperson said the cause of death was not yet known and parks and wildlife staff would continue to monitor the site.

"[Staff will] conduct a marine survey tomorrow to confirm the best approach," they said.

The department has warned of an increased shark and crocodile risk for the area and has asked people to stay away.

'Not an everyday sighting'

Melon-headed whales, also referred to as little killer whales or many-toothed blackfish by scientists, are part of the dolphin family.

The species congregate in large groups and are widespread across tropical waters.

Wildlife scientist Vanessa Pirotta from Macquarie University in New South Wales said the deaths were unusual, even in tropical waters.

"Like most marine mammals they're a really cool design," she said.

She believed the animals had been on the shore for a short time because there was no smell or bloating, but their injuries were mysterious.

"They did have tail injuries and the first one I looked at had a piercing just near the dorsal fin ... there was no blood or anything," Ms Spence said.

"One of them had a wound to its belly."

She said the discovery had clouded her enjoyment of the morning's crabbing trip and walk.

"It was really sad actually because we fish there regularly.

"Just at Christmas we were there ... and we had a whole heap of snubfin dolphins go frolicking past, so that was really beautiful to see."

"They're perfectly equipped for the marine environment, they have their blowhole and their nose at the top of their head and they've got spiky teeth so they are an oceanic dolphin."

Dr Pirotta said the whale deaths were an "unfortunate loss of life".

"The good thing is that scientists have been informed," she said.

"For some species, it's only the case that when they strand or when something like this happens that we learn about their presence."

Melon-headed whales grow to about 2.5m.

Ms Spence estimated the three dead animals found this morning measured 1.5m.