West Australian environment officers have put down a juvenile humpback whale stranded on a beach near Jurien Bay.

The 15-tonne juvenile was first spotted rolling on a reef last Thursday and then became beached one kilometre south of Jurien Bay in the state's mid-west region.

The Department of Environment and Conservation (DEC) had speculated the whale was chronically ill.

The department acknowledged calls to push the whale back out to sea to give it a chance to survive.

But DEC Senior Wildlife Officer Doug Coughran said the whale was too ill and weak to move, and any such operation would have only prolonged its suffering.

"The animal is 10.5 metres long and weighs an estimated 15 tonnes," Mr Coughran said.

"Humpbacks rarely strand and do so only if they have serious health issues."

The whale was killed by explosives detonated near its brain. It was to be buried at the site.

AAP