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Simon McKinley is probably one of the ecologists who has seen the most sharks. Between 2016 and 2019, 372 of them passed before our eyes. During these three years, a team of researchers led by him deployed 110 Remote Decoyed Underwater Video (BRUV) systems in the eastern tropical Pacific. The over 167 hours of recording allowed me to corroborate what I already sensed: that I was faced with one of the greatest hotspot of sharks in the world. The discovery, published Wednesday in the scientific journal PLOS OneIt’s a relief for a scientific community terrified by the declining population of these predators. Several studies have shown that since 1970, the global abundance of sharks and manta rays has decreased by 71%.
Each dive allowed us to record, without disturbing the animals, the presence and behavior of the sharks attracted by the smell of the bait, placed 20 meters from the device’s cameras. The recordings also served to compare distributions and see up close the role they play in the ecosystem. The study is an unprecedented window into one of the most biodiverse and least studied areas in the world. A territory that provides clear clues about the threats of these charismatic sharks, such as fishing.
Enric Sala, National Geographic Explorer-in-Residence, founder of Pristine Seas, and co-author of the study, is blunt: “Our study reaffirms that marine reserves where there is no fishing work and marine life recover spectacularly, with benefits for everyone, including fishermen. The enemy of fishermen is overfishing, not marine reserves.”
The study, conducted by researchers from the Charles Darwin Foundation (CDF), in collaboration with National Geographic Pristine Seas, the Directorate of the Galapagos National Park and other regional research institutes, highlights the need to protect the oceans from human predation. “For me it was an honor to be able to carry out the research. I am very privileged to confirm with a scientific study what I had observed during the dive,” he says in a video call with América Futura. “After these three years, it is clear that marine protected areas are crucial for the conservation of these animals.”
This is an idea that the diver returns to several times, warning of the lethal consequences of human intrusions – such as illegal fishing or excessive tourism – and of global warming, which makes it difficult for species to access nutrients and food. McKinley says remote marine protected areas, including the Galapagos, Malpelo, Clipperton and Revillagigedo Islands, are home to some of the largest recorded shark populations in the world, including the Jubarte hammerhead shark, critically endangered. However, coastal protected areas show signs of serious depletion.
Similarly, the majority of Galapagos sharks observed at Clipperton were juvenile-sized, suggesting that this protected space functions as an important breeding site. In contrast, mostly larger and more mature individuals were measured in coastal areas, indicating that these sites serve as aggregation or feeding areas for adults.
“The oceanic islands of the eastern tropical Pacific represent a window into the past, where sharks and large predatory fish are the norm and not the exception,” Pelayo Salinas-de-León, principal investigator at the Charles Darwin Foundation and lead author of the study, said in a statement. “These areas provide insight into what a healthy ocean looks like and highlight the key role ocean conservation plays in protecting these last bastions from systematic overfishing.”
Of the 372 sharks recorded in the mission, seven different species were distinguished: the white tip shark (Carcharhinus albimarginatus), the Galapagos shark (C. galapagensis), blacktip shark (C. limbatus), tiger shark (cuvier galeopig), silky shark (C. falciformis), whitetip reef shark (Triaenodon obesus) and jubarte hammerhead sharks (Sphyrna lewini), in serious danger of extinction. “We were positively surprised by the fact that in Malpelo and the Galapagos they were very abundant,” he says of the latter.
This shark has become the emblem of tropical seas, not only for its unique T-shaped head, but for the mystery surrounding its large congregations on the islands and seamounts of the Pacific. In places like Cocos Island or the Galapagos they swim en masse. However, globally, this species is challenged by targeted fishing – mainly for the trade of its fins – and bycatch. For those who know, the lewini It is a thermometer of marine health and a reminder of the fragility of these ecosystems.
