Sharks and Rays are in serious decline!

A recent Global Study Published in Nature confirms Sharks and Rays are in serious decline!

The number of sharks found in the open oceans has plunged by 71% over the last 50 years, mainly due to over-fishing, according to the recent scientific study recently published in Nature.

Oceanic sharks and rays are vital to the health of vast marine ecosystems, but because they are hidden beneath the ocean surface, it has been difficult to assess and monitor their status. The study represents the first global analysis of the state of shark species and is a wakeup call to the impact humans are having on the world’s oceans.

Giant Manta Ray hovering Over a coral reef in the Seychelles allowing cleaner wrasse to pick off parasites.

Three-quarters of the shark species studied are threatened with extinction. For every 10 sharks found in the open ocean in the 1970s, only three would be found today. Sharks and rays are mainly caught for their meat, fins and liver oil. They are also captured for recreational fishing and turn up by accident in the catch of fishing boats that are targeting other stocks. 

Of the 31 species studied, 24 are now threatened with extinction, and three shark species (the oceanic whitetip shark, and the scalloped and great hammerhead sharks) have declined so sharply they are now classified as critically endangered – the highest threat category, according to the International Union for Conservation of Nature (IUCN). Oceanic sharks and rays are at exceptionally high risk of extinction which jeopardizes the health of entire ocean ecosystems as well as food security for some of the world’s poorest countries.

Giant Hammerhead Shark hunting Sting Rays along shallow sand banks in the Bahamas.

The researchers compiled global data on sharks and rays found in the open oceans. 

Of the 1,200 or so species of sharks and rays in the world, only 31 are truly oceanic, travelling large distances across the world’s oceans. Not only are the charismatic ocean predators under threat, but some of the world’s most unusual sharks and rays are also on the brink of extinction. Reef Sharks are now rarely seen at almost one in five of the world’s coral reefs, a major study has found. The crash in shark numbers, could have dire consequences for corals struggling to survive in a changing climate. 

Schooling Grey Reef Sharks, hunting coral reef fish on an offshore reef in the Seychelles

Most sharks are at the top of the food chain, which makes them crucial to the health of the oceans.  Losing them would have a big impact on other fish populations. Fishing, both targeted and accidental, was to blame for the steep decline in many of these populations, together with habitat loss due to coastal development, degradation of mangrove forests, water pollution and trawling.

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. There is widespread loss of reef sharks across much of the world’s tropical oceans. Species such as grey reef sharks, blacktip reef sharks, and Caribbean reef sharks were often missing from reefs where they would historically have been found.

Scientists carried out baited underwater video studies on 371 reefs across 58 countries from the Central Pacific to the Bahamas. Bait was attached to a pole at the front of the cameras to attract any nearby sharks. Almost no sharks were detected on any of the 69 reefs of six nations: the Dominican Republic, the French West Indies, Kenya, Vietnam, the Windward Dutch Antilles and Qatar.

International political will is needed to reverse the decline in shark species, Governments need to work together to implement measures that are needed to reduce the take of sharks and these decisions will only come if there is pressure from citizens and conservation organizations. 

There are a few shark conservation stories that give some cause for hope. A couple of species, including the great white, have started to recover through science-based fishing limits and fishing bans. Relatively simple safeguards can help to save sharks and rays. 

By regulating how sharks are fished, populations have a chance to recover. Restricting certain gear types and setting catch limits, to national-scale bans on catches and trade can reduce the pressure on sharks throughout the world’s oceans.

Bathed in sunlight, a large, female white shark investigates a shoal of anchovy at the surface in Mexico.

Sharks are at the top of the food chain, and crucial to the health of the oceans. Estimates suggest that 100 million sharks are killed by people each year which is not sustainable.

Dr Chris Clarke

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