by Landing a 2 meter shark is a three-man job: two to wrap ropes around its striking tail and middle of the king, a third to clamp its powerful jaws. Hanging over the side of the Sea Quest fishing skiff, the crew work quickly to minimize any distress to the animal, a female silky shark. Once on board, a hose connected to a saltwater pump is placed in her mouth to irrigate her gills.
Catching and tagging sharks is controversial among some researchers, who say it is harmful. But for Alex Hearn, professor of biology at Quito’s Universidad de San Francisco in Ecuador, who has studied sharks for twenty years, it is essential to understand behavior that could better protect one of the most vertebrate groups. most endangered on the planet.
“This looks a little brutal,” says Hearn, picking up a power drill to drill the four holes needed in the silk’s dorsal fin to attach the tag. “But it is the most effective method. Sharks do not have nerve endings on their fins; it’s restricting what stresses them out more.”
The shark does not spawn and is back in the waters of the Galápagos archipelago, in the eastern Pacific Ocean, within six and a half minutes. They call her Isabela, after the largest of the islands, 620 miles from mainland Ecuador.
“When we tag these animals to track their movements, we’re taking a picture of underwater highways,” says Hearn, during a two-week Greenpeace trip to the region in March.
“Are there certain areas that they like to grow? When they move between those areas, do they follow predictable paths or migration routes?”
The tightly regulated waters of the Galápagos reserve, a Unesco world heritage site, rate among the best diving spots in the world due to its abundance of hammerheads, whale sharks, turtles and other megafauna. Some researchers believe it has the highest shark biomass in the world.
But once these highly mobile species move outside the reserve, they are at risk of overfishing. Despite their endangered status, many have been caught and killed by industrial fleets around the waters.
For scientists like Hearn, who are trying to figure out how best to protect them, time is running out.
The world’s population of sharks and rays has fallen by 70% in the last 50 years, due to overfishing, a threat exacerbated by habitat loss and the climate crisis. A third of all shark species, targeted for their fins and meat, and half of the 31 oceanic sharks are now threatened with extinction.
Shark fishing is prohibited, along with the use of longlines, a tuna fishing technique that leads to high “bycatch” of sharks within the marine reserve. But migratory species that swim outside it and into international waters can be caught legally.
That’s why Hearn and Greenpeace are pushing for additional protections, especially on the high seas, an area outside national borders that is increasingly vulnerable to exploitation.
“The Galapagos marine reserve is not working for highly mobile species,” says Hearn, who co-founded MigraMar, a non-profit environmental organization involving scientists from California to Chile that maps the migratory routes of endangered marine species across the Eastern Pacific Ocean.
“That’s why we are looking at connecting MPA [marine protected areas]hotspots and waterways,” he says.
Hearn’s tracking data from MigraMar shows how threatened marine species, including hammerheads, whale sharks, tiger sharks and turtles, migrate northeast from the Galápagos, toward Costa Rica.
This information helped the Ecuadorian authorities increase the marine reserve by an additional 22,000 square miles in the year 2022.
The Galápágos marine reserve is not working for highly mobile species
Professor Alex Hearn
Called Hermandad (“fraternity”), the added protection represents half of the critical “swimway” used by sharks between Galápagos and Cocos Island national park off Costa Rica. In half of the protected area fishing is completely prohibited, and no long-lining is allowed in the other half.
On the bridge of Greenpeace’s ship, the Arctic Sunrise, Sophie Cooke, lead investigator for the environmental organisation’s campaign and sea voyage, points to a map on her laptop showing clusters of industrial fishing vessels around the archipelago.
“You can see what a difference Hermandad has made,” says Cooke, who compiled data from Global Fishing Watch. “When you look at the 2019-20 data, you can see that there were long lines around Hermandad. Now, when you look at 2020 to 2022, the long lines are gone.”
The next step, Hearn says, is to increase protection for those heavily fished species, such as silks, threshers and blue sharks. “We have a new tool, in the form of the UN global ocean treaty,” he says, referring to the convention that regulates the exploitation of the high seas, which 193 countries agreed to last year.
A few weeks after the trip, Hearn tells me Isabela is safe, still swimming in the reserve around San Cristobal where she was found. But the second tagged silky shark, which the crew named Wolf after another island, was not so successful. His tag hasn’t pinged its location in two weeks, so Hearn suspects it may have been caught by a longline fishing vessel.
Related: MSC orders inquiry into shark fins on Pacific tuna vessels
Cooke says Wolf’s disappearance follows a pattern seen in Hearn’s work in 2022, when tagged blue sharks were fished out almost immediately. Of eight blue sharks tagged that year, one was found by a Spanish trawler 1,200 miles away near Peru, another was found in an Ecuadorian port, also believed to have been caught, and the last two were seen near the high sea Three were last seen in the protected area.
“We also saw the blue sharks disappear after they went out to sea,” says Cooke. “They are disappearing when they leave protected areas. It reinforces the case that we want to protect the high seas.”
