New research has found that five key shark species found in reef habitats are at higher risk of extinction than previously thought, mainly due to overfishing. Published in Science, the study indicates that gray reef sharks (Carcharhinus amblyrhynchos), blacktip reef sharks (Carcharhinus melanopterus), whitetip reef sharks (Triaenodon obesus), nurse sharks (Ginglymostoma cirratum) and Caribbean reef sharks (Carcharhinus perezi) declined by 60-73% across the world. As these sharks have disappeared from reefs, rays have begun to take over, except in places where both sharks and rays are being depleted, according to the study. This research builds upon a 2020 study in Nature that found that sharks were functionally extinct from about 20% of the worlds coral reefs. That [Nature] study basically grouped all of the sharks that occur on coral reefs together in one group and looked at what was going on, Colin Simpfendorfer, lead author of the new study and adjunct professor of marine and aquaculture science at James Cook University in Australia, told Mongabay. What weve done with this study is weve actually broken it down into individual species so we could look at what is happening to communities of sharks and rays. A reef shark visiting a baited underwater video station in the Caribbean. Image by Global Fin Print. Early results of the study were used to update the status of four of the shark species on the IUCN Red List: the gray reef shark and Caribbean reef shark are now listed as endangered, and the blacktip reefThis article was originally published on Mongabay