350 million years ago...

Millions of sharks are killed every year in the world.  It is easily deducible, that a massacre like this cannot carry on over the years and as a consequence, it seriously compromises the existence of the shark populations which are affected.  This worry, is based on the fact that sharks are not very prolific due to their reproductive system which is similar to mammals.  

In the light of these considerations, which have been already made, the apprehension of research associations is justified about the uncertain future of many shark populations.  Sharks have always been fished by humans, but it is only recently, that due to the decrease in the most commercially valued fish species, that this breed has reached unsustainable proportions...