Why are we so worried about sharks?

Sharks are the ocean’s apex predators, meaning they are at the top of the food web. While this may sound scary, what’s really scary is what may happen if they are gone. By eating other fish, sharks control their populations, and by picking off the weakest as prey, sharks keep those fish populations strong.

Now, I really should have changed that first sentence. Sharks aren’t at the top of the food web anymore – people are. Data suggest humans kill up to 73 million sharks per year, (though the authors of this paper acknowledge that’s probably a low estimate due to the lack of data on illegal fishing) and most of them are victims of finning, in which the shark is caught and hauled aboard to have its fins sliced off while it is still alive. The fins will be used to add texture to shark fin soup, a Chinese delicacy, while the rest of the shark is thrown back into the water to die, wasting up to 98% of the animal.

Photo: Shmulik Blum

Shark numbers have dropped dramatically over the last 50 years. Many species have decreased by 90% and some shark populations have almost disappeared. For example, in the Northwest Atlantic and Caribbean Sea, the scalloped hammerhead population may be down to just 2% of its size prior to the 1970s. According to the IUCN, out of all species of sharks and rays, 32% are threatened with extinction. 

This is an incredible problem for the health of the ocean. The disappearance of sharks from marine ecosystems can lead to a trophic cascade – a wave of effects that rides from the top down to the bottom of the food web, altering the entire environment.

It would be tragic to see sharks, which have survived on this planet for over 400 million years and gotten through multiple mass extinctions, disappear just because of humans’ greed or carelessness, but the consequences would be far more tangible than that. Sharks keep the ecosystem in balance, so the ocean can continue to provide us with food, oxygen, and other resources. More recently they’ve also become economically important as a major draw for tourism. A study in Palau found that while a single dead reef shark would be worth US$108, it could bring in $179,000 per year ($1.9 million in its lifetime) in tourism revenue, if alive. Shark diving contributes about $18 million per year to Palau’s economy.

The bottom line is that sharks keep the ocean healthy, and the ocean keeps humans healthy, so it’s for our own sake that we should all start fighting to protect and restore these magnificent animals. 

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