Study finds sharks are vanishing, and that's a "crisis" for humans

A new report has revealed an alarming drop in worldwide shark populations. The unprecedented global study found that sharks have simply vanished from many places. Before the pandemic struck, CBS News correspondent Mark Phillips spent a day at sea with the lead authors of the study.

Phillips' report on the research is the latest in our "Eye on Earth" series, which you'll see only on "CBS This Morning."

Off the coast of Florida, near Palm Beach, Phillips joined the team hunting for sharks — not because the predators are again in the news for all the wrong reasons, but because, in a lot of places, there are too few of them for our own good.

The authors of the study, which was backed in part by funding from late Microsoft co-founder Paul Allen, relied on a simple contraption with a complicated name.

Baited Remote Underwater Video, BRUV for short, is basically a cage with bait in one end and a camera at the other.

Damian Chapman and Mike Heithaus helped conduct the most comprehensive worldwide shark survey ever. They don't claim to have invented the photo trap, but they do believe they've "perfected it."

Over four years, the team have dropped the devices to the ocean floor more than 15,000 times in 58 different countries for the project they call FinPrint.    

The idea is to leave the BRUV down there for an hour and see how many sharks show up. Sometimes, in some places, they see quite a few. Sometimes, none.

"On the almost 400 reefs that have been surveyed around the world, 20% of them, we didn't see a single shark," Heithaus said, adding that that one figure in itself was a clear indicator of the problem.

Caught by fishermen, sometimes accidentally but often on purpose to satisfy the growing shark meat market, populations have crashed.

In one drop that CBS News watched off the Florida coast, the pickings were slim. In fact, a loggerhead turtle seemed more interested in the free lunch than the few sharks were. 

By using the same setup, recording for the same amount of time on each drop around the world, the researchers have been able to draw the first comprehensive, data-based conclusions about worldwide shark numbers.

"I absolutely think this is a crisis," Chapman told Phillips. But it's a different kind of crisis - one the researches have given a very specific definition.

"For our survey, we use the term functional extinction," said Chapman.

By that, they mean there may be some sharks around, but there are not enough of them to perform their essential role of controlling other marine life populations.

"You might think, 'hey, let's get rid of predators, they eat fish so we can have more fish,' but it actually doesn't work that way," said Heithaus, joking that "sharks definitely need a new PR agency," given the animals' fearsome reputation.

"What we're really seeing is that you need to have healthy shark populations, you need to have healthy reefs, and that's going to ultimately help people, too," he explained.

There were bright spots in the study. Where marine protection zones have been introduced, or fishing restrictions tightened so that fewer sharks are caught, their numbers have begun to come back. 

The study wasn't only about gathering knowledge, it was about gathering ammunition; a way to convince governments and fishing communities around the world to do something.