Blue whales end up as ‘ocean road deaths’ in crowded Patagonian waters

It took five grueling hours for Frederick Toro Cortes, a wildlife veterinarian at Santo Tomás University in Chile, and his team to perform an autopsy on the wet, uneven pebbles. Divided into three groups, they used large butcher knives to penetrate the thick layer of fat and muscle at three key points on the whale’s body: the upper back, belly and skull.

Beneath the wrinkled skin and fat, the researchers found 10 liters of blood – evidence of internal bleeding – and a 31.5 inch (80 centimeter) bruise (hematoma) at the base of his heart. The injury was probably the result of blunt trauma to the chest. Whales have no natural predators. Toro Cortes suspects the whale collided with one of the many ships that cruise these waters.

“The only thing that can generate this in these animals is a collision with a high-speed ship,” he said.

“It is very difficult for a 14-meter blue whale to die from a trauma caused by a rock in the middle of the sea. Moreover, there are no predators that carry out this type of strategy to hunt juveniles. ”

During the same week, a film crew filmed Toro Cortes performing the autopsy in April 2021 as part of the new CNN Original series “Patagonia: Life on the Edge of the World”, two more whales have been reported dead in Chilean waters. Typically, Chile records four dead whales a year, Toro Cortes said.
The autopsy confirmed that the dead marine mammal was a 4-year-old male. Blue whales, the largest animals known to have ever existed on Earth, can live for up to 100 years. If the young whale had survived, she could have sired more than 20 calves.

“With the autopsy, we can prove they are dying,” Toro Cortes said on the CNN original series. “It allows us to put pressure on the government to regulate maritime traffic.”

High traffic area

The finger-shaped fjords, sheltered bays and inland seas of the Pacific Patagonian coast off Chile are important summer feeding grounds for blue whales. The nutrient-rich fresh water from the steep valleys mixes with the ocean, creating dense patches of krill – tiny crustaceans that blue whales scoop up in the millions with their massive jaws.

The International Whaling Commission has identified the area as one of 12 with whale populations at risk. Since 2007, the commission has recorded at least 1,200 collisions between ships and whales around the world. However, for every accident observed and reported, there will be many more completely unnoticed.
Understanding how many whales are killed by ships and what that means for their conservation is difficult, but some researchers believe deadly encounters may explain why blue whale numbers have not fully recovered from decimation by commercial whaling. .

“People don’t realize what a global problem this is. These charismatic animals – everyone loves whales – have actually become prey to the ocean,” said Susannah Buchan, an oceanographer at the University of Conception in Chile.

In the inland seas off Chilean Patagonia, boats linked to industrial salmon farming pose a great threat. The salmon is not native to the southern hemisphere, but the rich water conditions mimic those found off the coasts of Scotland and Norway. Chile has become the world’s second largest producer of farmed salmon and the largest exporter to the United States.

“I think we had this image of Patagonia, and it’s like this vast wilderness, maybe on land, of course. But the marine environment is heavily industrialized due to salmon farming,” Buchan said.

“And so that means there’s a huge traffic of big barges carrying the salmon that’s been harvested or barges carrying the larval stages, or antibiotics or… food for the salmon. So it there’s all this traffic happening in a fairly narrow area.”

Measures that might work along an open coastline – such as changing shipping routes – do not work with the geography of islands and coves.

Using satellite trackers placed on 14 whales off the coast of northern Chilean Patagonia and publicly available navigational information, researchers from a 2021 study found that the whales feed in spaces with heavy shipping traffic – and the majority of vessels belong to the salmon farming industry.

An animation (see below) based on some of the data the researchers gathered shows a lone blue spot – the whale – struggling with around 1,000 boats moving daily.

Additionally, by monitoring the whales’ diving patterns, Buchan also discovered that they surfaced more at night to feed on krill, making the mammals even harder for ships to spot.

“The captain could feel a bump or feel nothing.”

A whale love song

Using underwater microphones or hydrophones, Buchan has studied the acoustics of whales in Patagonian waters since 2007. She recorded tens of thousands of hours of blue whale songs and found that whales blue seas off the coast of Chile produce a unique dialect, although it is subsonic and cannot be heard by human ears.

“It’s a series of very low frequency pulses, like a kind of rumble, almost,” she said. “And the Chilean dialect maybe has a few more sounds. Maybe it’s a little more complex. And maybe it has higher frequency components.”

Susannah Buchan listens to blue whales with an underwater microphone in the Gulf of Corcovado in Chile.

Identifying this unique whale song, which only male blue whales do, has allowed Buchan and other conservationists to track and learn about population movements. However, the noise emitted by large ships is in the same frequency band as the songs emitted by blue whales, Buchan’s data also revealed. Their songs are masked by the noise of ships.

Listen to the song of the blue whale

Using underwater microphones or hydrophones, Buchan has studied the acoustics of whales in Patagonian waters since 2007 and found that blue whales off the coast of Chile produce a unique dialect, although it is subsonic and cannot be heard by human ears. This audio clip has been sped up by 3 to highlight the sound of the blue whale.

Source: S. Buchan / Coastal COPAS

“These calls, which are reproductive calls presumably from males to females so they can come together and reproduce, can no longer be heard between individuals,” she said. “We also know from other species that ship noise increases physiological stress in these animals. So when all mammals are stressed, even humans, reproductive outcomes are affected. So they have fewer babies.”

Toro Cortes, the wildlife vet who performed the blue whale autopsy, has also worked with humpback whales off the southern tip of Patagonia in the Francisco Coloane Marine Park in the Strait of Magellan. There he used drones to try to capture samples of mucus from the air beaks emitted from their vents.

He said he hopes the detection of stress hormones in the samples will help to advocate for better regulation in this sea area, so that ships slow down as whales pass.

“Ship traffic can cause real stress and affect their behavior and even change where they feed,” Toro Cortes said in “Patagonia: Life on the Edge of the World.”

The Patagonian Pacific coastal waters off Chile are important summer feeding grounds for blue whales. Credit: CNN Original Series “Life in Patagonia at the Edge of the World”

What’s happening

To reduce the risk of ship strikes, Buchan is working to develop a warning system for the waters off Chile’s Patagonian coast that will alert shipping traffic to the presence of whales. Moored buoys equipped with hydrophones to capture whale songs and transmission systems will produce alerts informing sailors of the likelihood of encountering whales on their routes, allowing them to slow down or change course.

“A slower traveling ship will make less noise,” Buchan said, “and a slower traveling ship will be less likely to fatally harm a whale.”

Similar systems have been successfully tested in the Atlantic Ocean off the coast of Maine and in the Pacific off the coast of California.

With funding from the World Wide Fund for Nature, prototype buoys are being built in the lab, and Buchan said she hopes they will soon be tested in the waters off Chile’s northern Patagonia.

“The whales are there on a mission to grow so they can survive for the rest of the year, and that’s their priority. For them to dodge all this (ship) traffic is a real disruption to their business. And it’s also dangerous,” Buchan said.

“An ocean without whales would be devastating to all of us. If we want healthy oceans, we want whales to be part of those ecosystems,” she said in the CNN original series.


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