Blue whales end up as ‘ocean’s roadkill’ in the crowded waters of Patagonia

By Katie Hunt, CNN

The blue whale’s giant corpse was lying washed up on a rocky beach on the Pacific coast of Patagonia, at the southern tip of South America. The huge mammal was 46 feet (14 meters) long, and its deflated body yielded no visible clue as to how it had died.

It took Frederick Toro Cortes, a wildlife veterinarian at Santo Tomás University in Chile, and his team five exhausting 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 in the whale’s body — its upper back, belly and skull.

Beneath the pleated skin and the blubber, the researchers found 10 liters of blood — evidence of internal bleeding — and a 31.5-inch (80-centimeter) bruise (hematoma) at the base of its heart. The injury was likely a result of blunt force trauma to the chest. Whales have no natural predators. Toro Cortes suspected the whale collided with one of the increasing number of vessels that travel through these waters.

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

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

In the same week a film crew documented Toro Cortes conducting the autopsy in April 2021 as part of the new CNN Original Series “Patagonia: Life on the Edge of the World,” two other whales were 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 male and 4 years old. Blue whales, the largest animals known to have ever existed on Earth, can live to be 100. Had the young whale survived, it might have fathered more than 20 calves.

“With the postmortem we can prove that they are dying,” Toro Cortes said in the CNN Original Series. “This allows us to put pressure on the government to regulate ship traffic.”

High-traffic zone

The fingerlike fjords, sheltered bays and inner seas of the Patagonian Pacific coast off Chile are important summer feeding grounds for blue whales. Nutrient-rich fresh water from the steeply sided valleys mixes with the ocean, creating dense patches of krill — tiny crustaceans that blue whales scoop up by the million with their massive jaws.

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

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

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

In the inner seas off Chilean Patagonia, boats connected to industrial salmon farming pose a big threat. Salmon aren’t 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’ve had this image of Patagonia, and it’s like this vast wilderness, maybe on land, for sure. But the marine environment is heavily industrialized due to the salmon farming,” Buchan said.

“And so that means that there’s huge amounts of traffic from large barges that transport the salmon that have been harvested or barges that transport the larval stages, or antibiotics or … food for the salmon. So there’s all this traffic going on in quite a narrow area.”

Measures that might work along an open coastline — such as changing shipping routes — 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 shipping information, researchers of a 2021 study found that the whales feed in spaces subject to intense marine traffic — and the majority of vessels belonged to the salmon farming industry.

An animation (see below) based on some of the data researchers collated shows a lonely blue dot — the whale — contending with around 1,000 boats moving daily.

What’s more, from monitoring the dive patterns of the whales, Buchan said she also discovered that they surface more at night to feed on krill — making the mammals even harder for ships to spot.

“The captain might feel a bump or not feel anything.”

A whale love song

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

“It’s a series of very low-frequency pulses, like a kind of rumbling, almost,” she said. “And the Chilean dialect maybe has a few extra sounds. It’s maybe slightly more complex. And maybe it’s got some higher-frequency components.”

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

“These calls, which are reproductive calls likely from males to females so that they can get 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 less babies.”

Toro Cortes, the wildlife veterinarian who performed the blue whale necropsy, has also worked with humpback whales off the southern tip of Patagonia in Francisco Coloane Marine Park in the Straits of Magellan. There, he has used drones to try and capture mucus samples from the spouts of air emitted from their blowholes.

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

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

What’s being done

To reduce the risk of ship strikes, Buchan is working to develop a warning system for waters off Chile’s Patagonian coast that will warn ship traffic to the presence of whales. Moored buoys equipped with hydrophones to capture whale songs and transmission systems will produce alerts informing mariners how likely they are to encounter whales on their routes, allowing them to slow down or reroute.

“A ship that’s traveling slower will make less noise,” Buchan said, “and a ship that’s traveling slower will be 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 California’s coast.

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

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

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

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