Scientists were surprised to find salmonella in autopsies of whales that died in mass strandings

When dozens of pilot whales died in two separate mass strandings off the coast of Washington in the past 16 months, scientists at the Department of Biodiversity Conservation and Attractions (DBCA) were determined to find out the cause.

Last July, 97 pilot whales died at Cheynes Beach near Albany and another 31 died at Toby Inlet off Dunsborough in April this year.

In search of answers to the mass extinction, marine researchers took swabs and blood samples and even removed the heads of some whales for CT scans.

“We first look for diseases or can rule out diseases,” said Dr. DBCA marine scientist Holly Raudino tells Nadia Mitsopoulos on ABC Radio Perth.

“Particularly those (diseases) that are contagious to humans, things like bird flu, Brucella and also something called Cetacean morbilliviru, which is not contagious to humans but which whales and dolphins can suffer from,” she said.

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Tests ruled out these illnesses, but showed something surprising: salmonella.

“It originally appeared in Cheynes Beach (Albany) and became stranded in several individuals,” she said.

“We have been doing a follow-up survey of the more recent stranding at Toby Inlet (Dunsborough) and this has also appeared here and the reason it is interesting and surprising is because it has never been discovered before.”

“We’re just trying to figure out whether or not it might have contributed to the stranding.”

She said there were no records of Salmonella being detected in pilot whales.

Navigation difficulties excluded

In addition to testing for disease, the team also took on the logistical challenge of maneuvering the heads of three whales into a CT scanner to determine whether there could be problems with the whales’ ears and disruptions to their sonar capabilities that could have caused them to drift away Off course.

“So far we have not identified any catastrophic injuries to their ear parts, such as holes or perforations,” said Dr. Raudino.

She said hearing damage could be ruled out as a cause of the two recent strandings in WA.

“However, it is something that has caused strandings elsewhere in the world,” she said.

“We see that there are different reasons for different strandings.

The strandings will continue

The team is also studying the whales’ behavior before stranding to see if there are any clues.

“In the case of Cheynes Beach, we were very lucky that several people took photos of the whales before they became stranded, which is actually quite unusual,” said Dr. Raudino.

“We often only find out about them when they land on the beach and are reported by the public.”

“So we’re looking at this behavior and trying to compare it to the behavior of wild pilot whales to see if there are any differences, anything that might help us in our response or early intervention.”

Although Dr. Raudino said scientists don’t have a definitive answer, but they are committed to continuing to work to understand why the mass strandings are occurring.

“We just keep looking. There really is no end,” said Dr. Raudino.

“This has been happening for thousands of years. It’s not new. And it will definitely stay that way in the future.”