What Would Happen If Sharks Went Extinct?

If movie franchises like Jaws and Sharknado have taught us anything, it's that sharks are voracious, aquatic hellspawn, whose sole enjoyment in life derives from dismembering a smorgasbord of screaming humans, preferably in skimpy swimming attire. And why not? It's a fun story trope. Sharks are excellent movie villains because they exude the cold and dispassionate precision of a psychopath, and the raw killing strength of a trained assassin. They're basically the perfect mashup of Hannibal Lecter and Conan the Barbarian — with gills. There's no question about it; if a shark is hungry and you're splashing about in the water like a distressed porpoise, it will eat you (unless you own an awesome stealth diving suit). 

But setting the ratings maelstrom of Discovery Channel's Shark Week aside, are sharks really the bad guys? And would the ocean be a better place without them? The short answer to both of those questions is no. 

According to the Scripps Institution of Oceanography, a healthy underwater ecosystem is one in which there are almost no unused by-products. Everything in the food web should be useful. As apex predators, sharks play a key role in maintaining that balance. There's a domino effect: if sharks weren't around to eat larger fish species, those larger fish would therefore prey more heavily on creatures that eat smaller organisms like algae and jellyfish, and then algae and jellyfish in turn would have nothing to keep them in check. Smithsonian Ocean paints a bleak picture of an ocean without sharks as a "sickly underwater swamp," filled with detritus, infested with jellyfish, and far less diverse and amazing than it is now.  

The scary reality is that many species of shark may indeed become extinct in the near future. As cited in National Geographic, researchers estimate that around 100 million sharks are killed every year. A Dalhousie University study of worldwide shark numbers (cited in the New York Times) found that sharks are under extreme threat globally. From the Atlantic to the Mediterranean, some shark numbers have declined by as much as 80 percent, thanks to aggressive fishing practices and diminishing fish stocks. 

Sharks are the good guys! Sure, they do have the slightly annoying habit of chomping on the occasional human. But an ocean without sharks would be an ecologically dismal place. Surely an arm or a foot here or there is a small price to pay for healthy oceans!