What happens next to dead Tasmanian pilot whales ‘a true natural wonder’

Some whales were rescued, but the vast majority died, creating a major problem: what to do with all the rotting whale carcasses?

The authorities decided to drag the dead animals out to sea, in the hope that they would eventually sink to the seabed.

Whales will be spotted along the coastline in Strahan, Australia, on September 21, 2022.  Hundreds of whale pilots are stranded in Macquarie Harbor on Tasmania's west coast during a mass beaching.
Whales stranded along the shoreline in Strahan, Tasmania. (Huon Aquaculture via Getty Images)
Hundreds of pilot whales have been stranded in Macquarie Harbor on Tasmania's west coast during a mass beaching.
Hundreds of pilot whales are stranded in Macquarie Harbor on Tasmania’s west coast. (Photo by Huon Aquaculture via Getty Images)
A photo of the stranded pilot whale on September 21, 2022. Photo: Department of Natural Resources and Environment Tasmania.
The stranding gave authorities the task of clearing the carcasses of the whales that could not be rescued. (NRE)

Such massive strandings of whales are sad to see.

But in this case, the aftermath presents a fascinating opportunity for scientific discovery.

As the dead whales decompose, an astonishing and rare sequence of events is likely to flow through the marine ecosystem – eventually leading to an explosion of activity and new life.

Mass whale strandings are fairly regular – especially in Tasmania – but no one really knows why.

One of the 14 dead sperm whales washed up on a beach off King Island, north of Tasmania, Australia, Tuesday, September 20, 2022. The whales were discovered Monday afternoon on King Island, part of the state of Tasmania in the Bass Strait between Melbourne and the Tasmania's north coast, the Department of Natural Resources and the Environment said in a statement.  (Department of Natural Resources and Environment Tasmania via AP)
One of the 14 dead sperm whales washed up on a beach on King Island, north of Tasmania, on Sept. 20. (NRE)

As many were pulled out to sea, some of those carcasses washed up and were left to rot on the beach — a completely natural process.

Pilot whales, however, are large animals.

Some of the beached whales pictured from the previous 2020 stranding in Macquarie Harbour.
Some of the beached whales pictured from the previous 2020 stranding in Macquarie Harbour. (Police Tasmania)

Males weigh up to 2300 kg, which means they take a long time to decompose.

The smell of two tons of rotting whale blubber quickly becomes unbearable, so carcasses are often buried.

This time, the authorities decided to drag the dead animals out to sea.

It was reported that local salmon farm workers took nearly 11 hours to clean up 204 dead whales with a combined weight of between 500 and 600 tons.

They were tied to a 400-meter rope and dragged by boats for 40 kilometers before being dropped into deep water in the Indian Ocean.

Some carcasses may rewind to shore, but most are likely to disperse with the tides and currents.

The big question is: what happens to all that whale mass that is dumped into the sea?

Initially, a dead whale tends to float to the surface as it begins to decompose and expand its entrails with gas.

If this happens, ocean scavengers like sharks and seabirds are likely to feast on the remains.

A dead whale has caused a shark feed off the coast of WA.
Last November, a shark was bitten off the coast of WA while feeding on a dead whale. (9News)

Some people may be concerned that whale carcasses attract sharks that could pose a risk to humans.

Admittedly, shark-human encounters are emerging in Australia and elsewhere. But they are still very rare.
A report to the Western Australian government in 2012 found that whale carcasses were a risk factor for shark attacks, and said caution should be exercised near a dead whale in the water.
A humpback whale carcass has washed up on the NSW coast - with a huge chunk pulled out of its side.
In June, a humpback whale carcass washed up on New Zealand’s coast — with a huge chunk out of its side. (John123)

But the same report noted that of the 26 shark attacks examined, the highest number occurred more than a kilometer offshore.

Research has shown the chances of whale carcasses washing to shore, where shark scavenging can be observed, is slim.

So as long as the carcass is taken far from shore and people keep their distance from it, the threat to humans from shark encounters appears to be extremely low.

From death comes new life

Inevitably, the whale carcass will begin to sink.

Most ocean life is found fairly close to the sea’s surface, so if the water is relatively shallow, much of what’s left of the carcass will be quickly eaten by scavengers once it reaches the sea floor.

But these carcasses were discarded in deep water.

The deep ocean can be a barren place, where rich food sources are rare.

So the appearance of a single whale carcass can boost an entire ecosystem.

New life and activity can erupt around the dead animal in a very short time.

This process is known as “whale trap” and has been studied by scientists, sometimes using remotely operated vehicles.

On the seabed of the North Pacific, whales have been found to fall: survival support of at least 12,490 organisms from 43 species.
Whales collide with paddleboarders in Argentina

Pod whales get close to two paddleboarders

Deep sea sharks will get the most out of the carcass.

A host of other animals, including hagfish, squid, crabs, lobsters, worms and sea cucumbers, also participate.

All the while, bacteria are quietly working away in the background.

According to At the British Museum of Natural History, a single whale can provide food for animals for up to two years during the cleanup phase.

Other animals and bacteria survive from the chemicals produced from the decaying carcass.

These organisms, known as “chemotrophs,” were thought to be unique to underwater volcanic vents, where they use hydrogen sulfide as the main source of energy.

Research has recruited a similar array of animals around dead and decaying whales – generating a completely independent ecosystem from a gas that smells like rotten eggs.

Only a few organisms can break down the bones that remain, in a process that can take up to ten years.

So take a moment to consider the effect of 204 whales in a small part of the ocean off Tasmania.

At this point, they are likely generating interconnected marine metropolises, such as are rarely seen.

This story originally appeared on The conversation and is republished here with permission.

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