Scientists at the University of Aberdeen have published a paper stating that 70 percent of the world's oceans are shark free. Sharks don't live below 3000 meters, like many bony fishes, and congregate primarily in areas where humans fish.
That is a problem. "Sharks may be more vulnerable to over exploration than previously thought," the scientists concluded.
The study was conducted by taking samples with a trawler over a three year period in the North Atlantic. The group also looked at the records of commercial fishermen over several years.