Study: Oceanic shark and ray populations plummet globally

The number of oceanic sharks and rays has declined 71% globally over the last 50 years, according to a peer-reviewed study published in the journal Nature on Wednesday.

Why it matters: The study finds that fishing prohibitions and catch limits "are urgently needed to avert population collapse" and avoid ecological disruption.

What they found: 24 of the 31 total species of sharks and rays are currently at risk of extinction, AP reports, while scalloped hammerhead sharks, great hammerheads and oceanic whitetip sharks are critically endangered.

What they're saying: “You drop a fishing line in the open ocean, and often it’s sharks that are there first — whether or not they’re the primary target,” marine biologist Stuart Sandin told the AP, in reference to the study.

• “When you remove top predators of the ocean, it impacts every part of the marine food web,” Stuart Pimm, an ecologist at Duke University who was not involved in the Nature study, told AP.
• “Sharks are like the lions, tigers and bears of the ocean world, and they help keep the rest of the ecosystem in balance.”