An Ocean Without Sharks

Rose Boardman

Since the creation of Jaws, sharks have fallen victim to a bizarre stereotype that society has created for them. Don’t get me wrong, Jaws is a pretty scary movie, but a future without sharks is even scarier.

Caribbean reef sharks cruising the waters of Bimini. Photo Jenny Bortoluzzi @SharkyJenny

Caribbean reef sharks cruising the waters of Bimini. Photo Jenny Bortoluzzi @SharkyJenny

Unfortunately, populations of sharks are declining in many parts of the ocean with an average of 100 million being killed every year. This decline is primarily related to the effects of fishing, habitat destruction, by catch and shark finning. Sharks grow slowly, mature late and produce very few young. Therefore, their populations increase at extremely low rates, leaving them extremely vulnerable to the true predators of the ocean …………..HUMANS.

So what would happen if every shark in the ocean disappeared today?

The food web would suffer

Sharks play a vital role in the ocean and are considered a ‘keystone’ species. As top predators of the food web, sharks regulate and maintain the balance of marine ecosystems by feeding on the animals below them. This means that if they are removed, the whole structure could collapse. Sharks also prey on the sick and weak. By removing diseased animals from ecosystems, they help prevent nasty outbreaks.

Seagrass beds could be overgrazed

Sharks can also regulate the behaviour of their prey and prevent overgrazing of habitats. Turtles, which are common prey for tiger sharks typically overgraze on seagrass beds. Scientists in Hawaii looked at the effect tiger sharks had on the presence of turtles and found that seagrass growth was higher in the areas where the sharks roamed. It was concluded that the tiger sharks aided in the regrowth and recovery of seagrass beds by scaring off grazers.

Coral reefs could vanish

Research has further shown that sharks are crucial for the health of coral reefs. Algae naturally grow on corals but is controlled and eaten by herbivorous fish. When sharks are in decline, the herbivore population crashes because the sharks are not around to eat what eats them. If more herbivores fish are being preyed upon less algae is eaten. This can lead to a powerful explosion of algae, which can outcompete corals and suffocate them.

A healthy, controlled coral reef. Photo: Caitlin Gilmour @_caitlingilmour

A healthy, controlled coral reef. Photo: Caitlin Gilmour @_caitlingilmour

As the number of sharks decline the oceans will suffer a range of consequences that may be irreversible. Therefore, it is extremely important to educate ourselves on the importance of sharks and enforce the correct management strategies to save and protect them.

Why not check out Shark Trust to find out more fintastic facts about sharks and why you should protect them.

Rising Tides is a series focussing on the current threats facing our ocean, how these are being tackled and what you can do to help

If you’ve enjoyed reading this article, look out for more articles from Rose and follow her here @oceandreaming94 // @roseboardman4