WASHINGTON (AP) — A new study in the journal Nature documents a steep decline in global shark and ray numbers in the past half century. Researchers found the abundance of oceanic sharks and rays has dropped more than 70% between 1970 and 2018. And 24 of the 31 oceanic species of sharks and rays are threatened with extinction, while three species are considered critically endangered. Climate change and pollution imperil shark survival, but increased fishing pressure is the greatest threat for every oceanic shark species. The research was published on Wednesday,