Study: Reef shark decline due to overfishing

The reef shark population has dropped to dangerously low numbers — way worse than researchers anticipated, according to a new study co-authored by Florida International University.

The global number of reef sharks, including gray reef, blacktip reef, whitetip reef, nurse and Caribbean reef sharks, has sharply declined by 60 to 73 percent, the study shows.

While the picture originally looked bleak, researchers were unaware of how close these species were to extinction. “This tells us the problem for sharks on coral reefs is far worse and more widespread than anyone thought,” said Colin Simpfendorfer, lead researcher and adjunct professor of Marine and Aquaculture Science at James Cook University in Australia, in a news release.

Overfishing is the culprit of the dwindling population, according to the five-year study. The research was supported by the Paul G. Allen Family Foundation, a philanthropic organization that supports the arts and environment. The study was completed in conjunction with more than 120 research institutions around the world.

While sharks living on coral reefs have decreased, the number of rays has filled the vacuum, creating potential ecological instability.

“We are seeing that when sharks disappear, that causes other changes in these ecosystems,” said Mike Heithaus, co-author of the study and executive dean of FIU’s College of Arts, Sciences & Education, in a news release. “Keeping shark populations healthy, or rebuilding them, is important for maintaining their roles for healthy reefs.”

But the reef shark populations seem to be relatively stable in Marine Protected Areas, according to the International Union for the Conservation of Nature.