WA melon-headed whale stranding investigation findings 'inconclusive'
The melon-headed whales were found by residents at Crab Creek, east of Broome and about 2,000 kilometres north of Perth, in January.
Melon-headed whales are small, toothed whales belonging to the oceanic dolphin family.
The Department of Biodiversity, Conservation and Attractions (DBCA) collected scientific information from the dead mammals to investigate the incident.
But it has since confirmed the cause of the stranding would remain unknown.
Marine scientist Holly Raudino said the species had only stranded twice previously in WA, so the incident was unusual and concerning.
She said research team members had done everything they could with the samples available.
"We hadn't anticipated how quickly the head and the soft tissues would decompose," she said.
"By the time we received the head, it appears that decomposition had already set in.
"We're always trying to improve on our efforts as much as we can and as funding permits."
Findings initially suggested the stranding was caused by intense noise, due to severe damage to the mammals' ears.
But because of significant decomposition, results regarding the ears were comprised and deemed inconclusive.
"Elsewhere in the world when this species is stranded, it's been suspected to be in relation to exposure to an intense noise source," Ms Raudino said.
The species is primarily found in deep water worldwide.
The whales travel in pods ranging from 100 to more than 1,000 members.
While the ultimate cause of the stranding is undetermined, Ms Raudino said the team's findings would help inform broader global understanding and research into strandings generally.
Envrions Kimberley executive director Martin Pritchard said the stranding had shocked residents.
He said it was disappointing the cause would not be fully understood.
"We have a world-class marine environment here and there's a responsibility on the government to make sure we know what's going on and to manage it properly," he said.
"We're a wealthy country; surely we've got the resources to monitor our marine life so we can understand what's been going on in our oceans."
Mr Pritchard said at the time of the incident there were reports of "very large noises" in the area cause by "pile drivers".
"We were concerned that could have had a direct impact on the whales," he said.
"Now we'll never know."
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