Blue whales end up ‘run over’ in the tumultuous waters of Patagonia

The giant blue whale body lay on a rocky beach on the Pacific coast of Patagonia, in the extreme south of South America. The huge mammal was 14 meters long and its deflated body gave no visible clue as to how it had died.

Frederick Toro Cortes, a wildlife veterinarian at Universidad Santo Tomás in Chile, and his team took five grueling hours 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.

Under the skin and fat, the researchers found 10 liters of blood – evidence of internal bleeding – and a 80-centimeter hematoma at the base of the heart. The injury likely resulted from blunt trauma to the chest. Whales have no natural predators. Toro Cortes suspected the whale collided with one of the growing vessels that travel through these waters.

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

“It is very difficult for a 14-meter blue whale to die from trauma from a rock in the middle of the sea. Also, there are no predators that make this kind of strategy to hunt juvenile whales.”

In the same week that a film crew documented Toro Cortes conducting the autopsy in April 2021, as part of the new original series by CNN “Patagonia: Life on the Edge of the World” [Vida nos Confins do Mundo, em tradução livre], two other whales were reported dead in Chilean waters. Typically, Chile records four dead whales a year, said Toro Cortes.

The autopsy confirmed that the dead marine mammal was male and 4 years old. Blue whales, the largest animals that ever lived on Earth, can live to be 100 years old. If the young whale had survived, it could have produced more than 20 calves.

“With the autopsy, we can prove that they are dying,” Toro Cortes told reporters. CNN . “This allows us to put pressure on the government to regulate ship traffic.”

heavy traffic zone

The finger-shaped fjords, protected bays and inland seas of the Pacific coast of Patagonia, Chile are important summer feeding grounds for blue whales. Nutrient-rich freshwater from steep-sided valleys mixes with the ocean, creating dense patches of krill — tiny crustaceans that blue whales scoop up by the millions with their massive jaws.

The International Whaling Commission has identified the region as one of 12 with whale populations at risk. Since 2007, the commission has recorded at least 1,200 collisions between ships and whales worldwide. However, for every incident observed and reported, there will be many others that are completely unnoticed.

Understanding how many whales are killed by ships and what that means for their conservation is challenging, but some researchers think these fatal encounters may explain why blue whale numbers have not fully recovered from the decimation of commercial whaling.

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

In the internal seas of Chilean Patagonia, boats linked to industrial salmon farming pose a great threat. Salmon is not native to the Southern Hemisphere, but the rich water conditions mimic those found off the coast 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 desert, maybe on land, for sure. But the marine environment is heavily industrialized due to salmon farming,” Buchan said.

“And that means there’s a huge amount of traffic from big barges that transport the salmon that has been harvested or barges that transport the larval stages, or antibiotics or… food for the salmon in a very narrow area.”

Measures that might work along an open coast – like changing shipping lanes – don’t work with the geography of islands and inlets.

Using satellite trackers placed on 14 whales off the coast of northern Chilean Patagonia and publicly available transport information, researchers from a 2021 study found that the whales forage in spaces subject to heavy maritime traffic – and most of the vessels belonged to the industry. of salmon farming.

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

What’s more, by monitoring the whales’ diving patterns, Buchan said he also found that they emerge more at night to feed on krill – making the mammals even more difficult for ships to spot.

“The captain may feel a blow or not feel anything at all.”

A whale love song

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

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

Identifying this unique whale call, which only males do, allowed Buchan and other conservationists to track and learn more about population movements. However, the noise that large ships make is in the same frequency range as the songs made by blue whales, Buchan’s data revealed. His songs are masked by the noise of the ships.

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

Toro Cortes, the wildlife veterinarian who performed the autopsy on the blue whale, also worked with humpback whales in the extreme south of Patagonia, in the Francisco Coloane Marine Park on the Strait of Magellan. There, he used drones to try to capture samples of mucus from the jets of air emitted by his blowholes.

He said he hopes the detection of stress hormones in the samples will help build a case for better regulations in this maritime area, so ships slow down as the whales pass.

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

what is being done

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

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

Similar systems have been tested with successful results in the Atlantic Ocean off the coast of Maine and in the Pacific off the coast of California in the United States.

With funding from the World Wildlife Fund, prototype buoys are being built at the lab, and Buchan said he hopes they will be tested in the waters of northern Chilean Patagonia soon.

“The whales are there on a mission to get fat so they can survive for the rest of the year, and that’s their priority. For them, running away from all this traffic (from ships) is a real interruption of that objective. And it’s also dangerous,” Buchan said.

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