On January 27, Nature published the first global assessment of shark and ray populations, and the findings are daunting. Oceanic shark and ray populations have declined by 71 percent since 1970, and likely by even more, due to incomplete data from some regions. The main culprit is overfishing.

Now, with more than three-quarters of oceanic shark and ray species threatened with extinction, scientists are calling on governments to implement science-based limits for shark fishing. Even if commercial fishing halts, however, shark populations will still be threatened, as they are often caught accidentally.

To combat this, scientists say fishermen should regularly monitor their lines, avoid shark hot spots, and use shark-friendly gear that allows them to break off the line without releasing tuna or swordfish. Currently, fishermen are not motivated to take these measures as many governments allow them to keep sharks, even species that are critically endangered, such as shortfin mako sharks, which are legal to fish in the United States, European Union, and many other countries.

According to Sonja Fordham, president of Shark Advocates International and an author of the Nature study, saving shark and ray populations is going to require intervention from governments around the globe, who should participate in discussions with conservationists and scientists to enact policies based on scientific evidence.