https://blogs.scientificamerican.com/observations/sympathy-for-the-devil-shark-week-should-remind-us-humans-are-the-apex-predator/

We’ve all seen the movies—the signature razor-sharp teeth, suspenseful music and murky underwater shots of one of the ocean’s mightiest predators quickly approaching its prey. With the airing of Shark Week approaching, there’s no better time to remember there’s much more to sharks than the movie villain version we so often see in theaters.

Whereas sharks are often portrayed as the scoundrelsof our waterways, these animals play a critical role in helping maintain healthy ocean ecosystems. Sharks keep marine populations in check, eating sick and weak prey to help improve the gene pool for stronger, healthier future generations. After sharks were seriously overfished around Australia, for instance, the octopus population increased dramatically and preyed heavily on spiny lobsters—decreasing the crustacean population and causing hardship to local lobster fishermen.