Scientists are concerned about the alarming rate in which sharks and rays are decreasing from our oceans. A study has found that 71% of the shark and ray population has declined over the last 50 years. The only species of sharks that has not been affected over this period of time is the smooth hammerhead. Humans are the direct cause of this impending extinctionUnsurprisingly so, the fishing industry is the number one cause for the decline of marine life and experts are now urging people to take immediate action so as to preserve the lives of these animals. Dr. Richard Sherley, of the University of Exeter, is currently undertaking the study. He says: For every 10 sharks you had in the open ocean in the 1970s, you would have three today, across these species, on average. These are some of the big, important, open ocean predators that people will be familiar with. The kind of sharks that people might describe as awe-inspiring or charismatic.Sherley explains that the only true solution to avoid this mass extinction is for human beings to actively pressure the government in taking the measures necessary to fight against overfishing. He adds: The science is there, there needs to be the desire to do those stock assessments, to implement the measures that are needed to reduce the take of sharks and that political will has to come from pressure from citizens.These animals are not only killed for what they can provide humans with, namely meat and oils, but they also die as the result of being caught inadvertently. Currently, there are 24 species classified as vulnerable, endangered or critically endangered by the International Union for Conservation of Nature (IUCN). The effects of overfishing can be reversibleAs seen with the Great White shark, endangered species can be saved from extinction when strictly enforced fishing regulations are implemented so as to monitor the amount of animals being caught. However, these measures must be put in place sooner rather than later. President of the Ocean Foundation's non profit project Shark Advocates International, Sonja Fordham believes that: Relatively simple safeguards can help to save sharks and rays, but time is running out. We urgently need conservation action across the globe to prevent myriad negative consequences and secure a brighter future for these extraordinary, irreplaceable animals.