DALHOUSE, Nova Scotia, July 29 (UPI) -- Canadian experts say over fishing has greatly reduced the diversity of fish, exposing ecosystems of the world's oceans more to threats like global warming.
Boris Worm, a biologist at Dalhousie University, in Nova Scotia and a lead author of the research, said, "The oceans have been drained of species, basically," the New York Times reported Friday.
Researchers found species diversity has fallen by half since the 1950s. Worm warned if areas where fish diversity persists are not protected, the sea ecosystems will become less resilient against environmental changes like global warming.
For their research, scientists studied decades of catch records from Japanese fishing fleets as well as data from U.S. and Australian government agencies. Their findings are reported in Friday's issue of the journal Science.
Researchers said it has been known for some time that over fishing has reduced species diversity in coastal areas but their study is the first broad look at diversity across open oceans, the report said.
Worm said lack of species diversity is a problem because ecosystems with fewer species are less robust in the face of environmental disruptions like climate change.
