A third of shark species face extinction. One man is trying to change that

Miami, Florida CNN —

Diego Cardeñosa has loved sharks ever since he was a child. The Colombia native was never afraid of them when he visited his beloved beach. Instead, he was fascinated with how sharks move through water using their multiple fins. It’s no surprise he became a marine biologist.

“As soon as I realized they were going through a conservation crisis, I wanted to help what I love the most,” said Cardeñosa.

Sharks need him more than ever. The International Union for the Conservation of Nature reports 35% of all shark species are threatened with extinction. That number has grown nearly 50% in a decade’s time.

The primary reason is overfishing; shark meat and fins are highly sought.

“They are being killed at a rate that cannot be sustained in the future,” said Cardeñosa.

Scientists worry the sharks’ dwindling numbers could bring ecological collapse as they play a number of key roles in the ocean.

Unlike many fish, sharks take a long time to reproduce. Fisheries kill about 100 million sharks a year, according to the non-profit Save Our Seas. Many sharks end up as bycatch when long lines and gill nets unintentionally catch them.

The largest demand that drives the international trade is shark fin soup. “Shark finning is problematic because when you remove the fins from a shark and you put it back in the water, it’s just like a rock or a log just falling to the bottom of the ocean,” said Cardeñosa.

“If they cannot swim, they will suffocate to death.”

Hammerheads are one of the of the most critically endangered sharks- having lost 80% of their population in just the last three decades.

“Their fins are big and really good quality,” said the scientist. “That means they’re thick and they have these