Whale shark by Tim Nicholson
Whale shark by Tim Nicholson

The new IUCN Red List reveals that growing human pressures on whale sharks and slender hammerhead sharks are putting these species at an increasing risk of extinction. Both the shark species are now listed as Endangered.

Numbers of whale sharks (Rhincodon typus), the world’s largest fish, have more than halved over the last 75 years as these slow-moving sharks continue to be fished and killed by ship propellers.

Although conservation action in India, the Philippines and Taiwan has ended large-scale fishing of whale sharks in these countries, they continue to be fished in other locations, including southern China and Oman. As whale sharks and tuna are often found together, the sharks are frequently caught by tuna fishing boats.

Unregulated fishing is also behind the fast-falling numbers of the distinctive slender hammerhead shark (Eusphyra blochii), whose shape makes it easily get tangled up in fishing nets. This species has moved from Near Threatened to Endangered on the IUCN Red List.

Eusphyra blochii - Slender Hammerhead or Winghead Shark. By CSIRO National fish Collection [CC BY 3.0 au]
Eusphyra blochii – Slender Hammerhead or Winghead Shark. By CSIRO National fish Collection [CC BY 3.0 au]

Although it is difficult to say how many individuals remain, recent surveys of fish markets in Indonesia found only one slender hammerhead shark among approximately 20,000 sharks of other species. A similar pattern is expected throughout Asian countries where coastal fishing is intense and largely unregulated.

“It is alarming to see such emblematic species slide towards extinction,” says Jane Smart, Director of IUCN’s Global Species Programme. “These new IUCN Red List assessments emphasise how urgent it is for the conservation community to act strategically to protect our planet’s incredible diversity of life.”

A full update to the IUCN Red List of Threatened Species, including assessments of many other species, will be announced at the IUCN World Conservation Congress 2016 to be held in Hawaii from 1 to 10 September.

Whale sharks are found in all tropical and warm seas except the Mediterranean. The rise of dive tourism in many areas is making the fish more valuable alive than dead in some locations, including at Ningaloo Reef in Western Australia, Donsol in the Philippines, Placencia in Belize and Isla Contoy in Mexico. In all these places, and in other countries like the Maldives, India, Thailand and Malaysia, the whale shark is protected. However, the whale shark migrates long distances out of the safe areas and into the fishing zones.

Further Reading

Rhincodon typus entry on the Red List
Eusphyra blochii entry on the Red List

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