Study finds sharks are ‘functionally extinct’ in 20% of reefs observed


(Credit: Unsplash)

This article is brought to you thanks to the collaboration of The European Sting with the World Economic Forum.

Author: Johnny Wood, Senior Writer, Formative Content

  • Illegal and irresponsible fishing has left sharks ‘functionally extinct’ in many of the world’s reef ecosystems, a new study says.
  • The size of populations is closely linked to the proximity, density and poverty levels of the nearest human communities.
  • Marine conservation areas, fishing restrictions and trade legislation can help protect and preserve species.

While most people would find a face-to-face encounter with a shark terrifying, humans are a greater threat to sharks than they are to us. And overfishing and exploitation have depleted species in many of the world’s ocean reefs, a new study shows.

Despite their image as feared marine predators, sharks are themselves hunted for their meat and fins, which are a sought-after delicacy in some countries. Many are simply in the wrong place at the wrong time, ending up as by-catch in fishing nets set for tuna and other fish species or caught up in drifting ‘ghost nets’ long abandoned by fishermen.

But in some parts of the world, conservation efforts are protecting shark populations, providing optimism for the future of a creature that has been around for hundreds of millions of years.

Human impact

Using video footage taken at more than 370 reef locations in 58 countries, researchers assessed the conservation status of sharks in different parts of the world. The study’s results, published in the scientific journal Nature, show an absence of sharks in 20% of the reefs surveyed. This is largely due to destructive and unsustainable fishing techniques – sharks have few offspring and mature slowly, leaving them vulnerable to overfishing.

Newly caught dogfish sharks are pulled aboard the Ocean Sunset commercial fishing boat in the Pacific Ocean off of Ucluelet, British Columbia June 25, 2012. The Ocean Sunset hunts sharks as well as other fish for their meat and fins. After the fishermen catch them, dogfish sharks are sent to a processing plant, the fins are removed and the body is skinned. The bellies are exported to Germany to be smoked for pub food, and the fins are sent to Asia, where they are used in shark fin soup - a delicacy in Chinese culture. Animal rights advocates criticise the shark fin harvest but others say that eating shark fins is an old cultural tradition. Picture taken June 25, 2012. REUTERS/Ben Nelms (CANADA - Tags: ENVIRONMENT ANIMALS FOOD SOCIETY)ATTENTION EDITORS: PICTURE 18 OF 22 FOR PACKAGE 'CANADA'S SHARK FIN SOUP'Search 'shark fin' for all images - GM1E8C6175C01
Overfishing is reducing some shark populations to low levels.
Image: REUTERS/Ben Nelms

The study found a strong relationship between reduced shark numbers and the proximity, density and poverty levels of the nearest human communities. Some poorer societies were found to be highly dependent on shark meat for food, for example, while ineffective governance failed to prevent overfishing, leaving sharks “functionally extinct” in eight of the countries surveyed.

Underwater videos recorded by the study team reveal a very different picture in countries such as the Bahamas and Australia, with strong management of fisheries and marine sanctuaries in place. In these places, the report describes “increased abundances of reef sharks”.

Occupying the top of the marine food chain, sharks help maintain balanced ocean ecosystems. Having few natural predators, sharks limit the populations of their prey, switching from one food source to another depending on what’s available. This ensures biological diversity by preventing one type of prey growing too dominant and disrupting things further down the food chain.

Environment and Natural Resource Security The Ocean Restoring ocean life
Extinction is a real threat for many species on land and sea.
Image: Statista

Almost a third of all species of sharks and rays face extinction, according to the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, part of a mass extinction threat looming for many land and marine animals. So, what can be done to protect shark populations?

Effective action

Sharks were found to thrive in countries that enforce marine protection areas, which prevent commercial fishing in certain places or for particular marine species. Shark fishing has been banned in the Bahamas for more than three decades, for example, helping the country lead the world in shark abundance, according to the report.

Effective marine management can include regulating fishing activity so sharks are caught less frequently, either intentionally or as collateral catch. Alternatively, legislation could be enforced banning harmful fishing techniques: gill nets are almost invisible to the multitude of marine species they entrap; and long-line fishermen trail hundreds or sometimes thousands of hooks in the water for long periods to catch fish indiscriminately, a technique which could be replaced with a more targeted approach.

What’s the World Economic Forum doing about the ocean?

Our oceans cover 70% of the world’s surface and account for 80% of the planet’s biodiversity. We can’t have a healthy future without healthy oceans – but they’re more vulnerable than ever because of climate change and pollution.

Tackling the grave threats to our oceans means working with leaders across sectors, from business to government to academia.

The World Economic Forum, in collaboration with the World Resources Institute, convenes the Friends of Ocean Action, a coalition of leaders working together to protect the seas. From a programme with the Indonesian government to cut plastic waste entering the sea to a global plan to track illegal fishing, the Friends are pushing for new solutions.

Climate change is an inextricable part of the threat to our oceans, with rising temperatures and acidification disrupting fragile ecosystems. The Forum runs a number of initiatives to support the shift to a low-carbon economy, including hosting the Alliance of CEO Climate Leaders, who have cut emissions in their companies by 9%.

Is your organisation interested in working with the World Economic Forum? Find out more here.

Similarly, the US and EU have enforced bans on the practice of removing shark fins at sea then discarding the carcass, reducing catch numbers by insisting the whole fish is brought to shore before removing the fins. Yet the illegal trade in shark fins persists.

Dr Andy Cornish of WWF points to the need to make the trade in shark products more transparent and more traceable, rejecting products from unsustainable or unknown origins in order to clamp down on illegal trade.

“Far too few people realize how bad the shark crisis is, and how much more costly and difficult solutions become the longer we delay. We must ask ourselves: Are we prepared to accept the consequences — moral, ecological, and economic — of letting dozens of species of sharks disappear forever on our watch?” he wrote on Medium Environment.

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