The James Cook University study, published in the Nature Communications journal today, found 59 per cent of 134 coral-reef associated shark and ray species are threatened with extinction.

It found 14 species are critically endangered.

The research found that losing the sharks and rays that live on reefs would have potentially catastrophic knock-on effects for coral reef systems.

JCU Adjunct Professor Colin Simpfendorfer, who was part of the international research team, said coral reefs faced some of the most intense and widespread threats of any ecosystem on the planet.

And sharks and rays were among the most threatened groups found on coral reefs, he said.

Without sharks and rays, both the number and behaviour of other species that live on the reefs would be affected, he said.

This means there would be ecological consequences that would upset the delicate balance of coral reefs globally that would be hard or impossible to reverse.

Simpfendorfer said the study showed coral reef sharks and rays were at almost twice the risk of all 1199 known shark and ray species.

“We found 59 per cent of coral reef shark and ray species are threatened with extinction, making them the most threatened group of animals on coral reefs in the world, after marine mammals.”

He said over-fishing was the main threat to these species, along with threats to their coral reef habitats and climate change.

Larger sharks and rays that live in shallower water were most at risk.

“Risk also increases for animals living in the waters of nations with greater fishing pressure and weaker governance,” Simpfendorfer said.

“What we need to see is immediate action through local protections, combined with broad-scale fisheries management and Marine Protected Areas.’’