Reef sharks in major global decline

Posted by Imogen Searra on 29 July 2020

Globally, sharks have been threatened by overfishing. A new study has found that sharks are ‘functionally extinct’ from one in five coral reefs. The study found that 19% of the world’s coral reefs are missing sharks. This is the largest decline in reef sharks ever recorded, according to Science Mag.

Reef sharks in major global decline

Sharks are hunted for their fins and meat and are often get entangled in fishing nets and gear.

Researchers identified that countries with dense human populations and little to no governance, sharks have been declared ‘functionally extinct’.

Other parts of the world, where conservation measures are in place, have an abundance of sharks. ‘Opportunities for the conservation of reef sharks remain: shark sanctuaries, closed areas, catch limits and an absence of gillnets and longlines were associated with a substantially higher relative abundance of reef sharks..’ read the study’s abstract.

‘At a time when corals are struggling to survive in a changing climate, losing reef sharks could have dire long-term consequences for entire reef systems,’ said Dr Mike Heithaus of Florida International University, according to BBC.

Grey reef sharks, Caribbean reef sharks and blacktip reef sharks, were not found along the reefs where they have been known to occur.

Sharks play a vital role in the marine ecosystem. They maintain the food chain of the species below them and are also an indicator of the ocean’s health, according to Oceana.

The study was conducted using underwater cameras, which were fitted on 371 reefs, across 58 countries, ranging from the Central Pacific to the Bahamas, according to BBC. Bait was fixed to the front of the camera on a pole in order to lure in any sharks.

Of the 69 reefs in the French West Indies, Kenya, Vietnam, Qatar, the Windward Dutch Antilles and the Dominical Republic – no sharks were detected.

‘From restricting certain gear types and setting catch limits, to national-scale bans on catches and trade – we now have a clear picture of what can be done to limit catches of reef sharks throughout the tropics,’ said Dr Aaron MacNeil of Dalhousie University in Canada, according to BBC.

If sharks are taken out of the coral reef ecosystem, coral reefs won’t be able to survive. Predatory fish, like groupers will be able to flourish and will feed predominantly on herbivores. With a lack of these species, macroalgae will then begin to flourish too. Reef systems will then be taken over by the algae and thus affecting the survival of coral entirely, according to Oceana.

Sharks are hunted for their fins and meat and are often get entangled in fishing nets and gear.

Image credit: Unsplash

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