By 3 News online staff
The mysterious death of 30 whales in the Gulf of Alaska over the past few months has baffled scientists and a large-scale response has been launched to figure out why they died.
The sheer number of unexplained deaths has led the US National Oceanic and Atmospheric Administration (NOAA) to declare an "unusual mortality event" which is put in place after an unexpected stranding or a significant die-off of mammals.
Since May this year, 11 fin whales, 14 humpback whales, a grey whale and four unidentified cetaceans have been found dead and floating in the ocean with the majority in a moderate to severe state of decomposition.
The number so far is already almost three times the historical annual average.
Scientists have so far only been able to get samples from one whale, but no definitive cause of death has been identified.
NOAA Fisheries marine mammal health and stranding response coordinator Dr Teri Rowles says scientists are concerned.
"While we do not yet know the cause of these strandings, our investigations will give us important information on the health of whales and the ecosystems where they live."
The declaration of an unusual mortality event allows federal, state and tribal groups to develop a response plan and conduct a scientific investigation into the cause.
The NOAA says six other dead, stranded whales were recently found along the coast of nearby British Columbia, with samples from two taken for analysis.
It is "highly unlikely" the whale deaths are linked to the Fukushima nuclear reactor meltdown because the analysis on the whale didn't show any unusual exposure to human-generated radionuclides.
Further testing will look for biotoxins and bacterial or viral agents as the possible cause.
It isn't clear whether there is any risk for humans of catching an infectious disease from contact with the mammals, the NOAA says.
But the answers might not come quickly, with results in such investigations taking months, if not years.