Sharks have been around for hundreds of millions of years, yet after all that time on the planet they are finally disappearing. The reason is no mystery: us.

Overfishing has been depriving a myriad of shark species of their prey and sharks themselves also fall victim to harmful fishing practices by becoming entangled in nets. Meanwhile, tens of millions of sharks are killed each day for their fins to be used in shark fin soup, which is widely considered a delicacy and a status dish in Chinese culture.

Sharks, of which nearly 500 species live in the planet’s seas and oceans, are crucial to marine ecosystems as top predators. Yet their days may well be numbered unless protection measures are stepped up worldwide.

A case in point is a comprehensive new global study of reefs, which has found that sharks are “functionally extinct” at nearly a fifth of the 371 reefs that have been surveyed in 58 countries.

“Our results reveal the profound impact that fishing has had on reef shark populations: we observed no sharks on almost 20% of the surveyed reefs,” the scientists behind the study write.

“Reef sharks were almost completely absent from reefs in several nations, and shark depletion was strongly related to socio-economic conditions such as the size and proximity of the nearest market, poor governance and the density of the human population,” they explain.

No sharks were seen on any of the 69 reefs in six nations: the Dominican Republic, the French West Indies, Kenya, Vietnam, the Windward Dutch Antilles and Qatar.

“This doesn’t mean there are never any sharks on these reefs, but what it does mean is that they are ‘functionally extinct’ — they are not playing their normal role in the ecosystem,” explains Prof. Colin Simpfendorfer, a scientist at James Cook University in Australia. “In these countries, only three sharks were observed during more than 800 survey hours,” he adds.

Sharks at many reefs, especially those closer to large human populations, are facing a variety of threats, including mass tourism. Destructive fishing practices are also taking their toll, not least blast fishing whereby explosives are thrown into the sea to stun or kill fish.

The situation sounds bleak, but not all is lost yet. By boosting conservation efforts of key marine areas, including reefs, we can still save sharks and a myriad of other threatened species like sea turtles.

Scientists recommend a variety of measures to protect marine ecosystems: setting up special sanctuaries for sharks, closing off certain areas to people, limiting the size of catches by fisherfolk, and banning fishing gear such as gillnets that pose a threat to bycatch animals like sharks and turtles.

Locals should also be enlisted in conservation efforts in order for these efforts to be successful. “Reef shark populations will only have a high chance of recovery by engaging key socio-economic aspects of tropical fisheries,” the authors of the study observe.

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