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Context

• The study, findings published in the Science journal, was conducted in 391 coral reefs spreading across 67 countries of the world.
• It was undertaken as a collaboration called Global FinPrint project.
• It studied 5 key species of reef sharks namely –
  • Caribbean reef shark
  • Nurse shark
  • Grey reef shark
  • Blacktip reef shark and
  • Whitetip reef shark
• This study highlighted the decline in reef sharks population by collecting and analysing video footage.

Other Details

• It was found that there is a decline of 60 to 73 per cent in these five key species’ population.
• Geographical areas covered were extending to
  • Indian Ocean off East Africa
  • Australia’s Great Barrier Reef
  • clusters of coral in the Caribbean
• Apart from these reef sharks, one-third of all sharks, ray, and other related species are also on the risk of extinction due to declining population.
• In the surveyed 391 reefs, in 34-47%, individual shark species was not found.
• In some places, sharks were not detected in 13.6 per cent of reefs at all.
• Most affected areas were –
  • Asia
  • Eastern Africa
  • South America, and the
  • Central-eastern Caribbean

Reef Sharks

• They are known by the scientific name Carcharhinus perezii.
• In marine ecosystems these sharks are considers indicator species and are the top predators of the coral reefs.
• There are many species of sharks found in reefs some of them are –
  • Blacktip reef shark
  • Grey reef shark
  • Whitetip reef shark
  • Galapagos shark
  • Caribbean reef shark

Habitat

• Shallow Tropic or subtropical water of coral reefs.
• That is shallow ocean regions close to the shore.
• Mangroves.
• Sea grass beds.

Significance

• These are very significant to coral reef system.
• They help in maintaining food webs.
• Nutrients cycling is also supported by them.
• They can promote economy by giving a push to tourism industry.

Conservation Status

• Current IUCN status is Near threatened.
• However study finds that these five key species should be classified as threatened as per International Union for Conservation of Nature Red List of Threatened Species.

Threat

• Overfishing is the key threat.
• They are killed for meat, leather, liver oil, and fishmeal.
• It leads to the domination of ray instead of shark which ultimately led to decline of both sharks and rays.
• Other marine activities which pollute the oceans.
• Degradation and destruction of Natural habitat.

Measures to be taken for conservation

• Right management techniques.
• Reefs could be converted or declared protected areas.
• Special programmes to conserve them like in Philippines and Indonesia.
• Enforcing rules and related regulations.
• Involvement of fishermen and sensitizing them about this ecological issue.

Indicator Species These are living organisms whose presence or absence indicates the changes in environment and the particular ecosystem. These living organisms could be plants, animals or microorganisms. These organisms are highly sensitive to any environmental changes. Hence any negative changes in such species growth, health or population indicate environmental stress. On the other hand good and healthy presences of them indicate the wellbeing of ecosystem and environment. For eg. Lichens.

Must read Article:

https://www.iasgyan.in/daily-current-affairs/coral-reefs

https://www.iasgyan.in/blogs/coral-reefs-around-the-world

https://www.iasgyan.in/daily-current-affairs/great-barrier-reef-40

PRACTICE QUESTION What are indicator species? Explain in context of reef sharks. By highlighting the threat reef sharks are facing, Elaborate how they play a key role in sustainability of the coral reef ecosystem. (150 words)

https://theprint.in/environment/reef-sharks-pushed-to-extinction-by-overfishing-up-to-73-decline-in-5-common-species-globally/1631418/