Blacktip reef sharks

The majestic black tip reef sharks of Koh Surin & Richelieu Rock

By David Castro

The Black tip reef shark (Carcharhinus melanopterus) has a wide distribution. It’s found in shallow waters in many parts of the world, including the Surin Islands and Richelieu Rock. Here in Thailand it is relatively common, along both the coasts and islands of the Andaman Sea and the Gulf of Thailand. Both Koh Surin and Richelieu Rock contain healthy populations of these harmless reef sharks. Despite its relative wide distribution, the species is now listed as Near Threatened by the International Union for the Conservation of Nature (IUCN). It’s greatest threat is over-fishing and habitat disturbance, leading to widespread regional declines of this slow-reproducing shark.

Distribution Map of the Black-tip Reef Shark

Distribution map of blacktip reef sharks
Map by By Chris_huh - Compagno, Leonard; Dando, Marc & Fowler, Sarah (2005). Sharks of the World. Collins Field Guides

Despite the decline in black-tip populations, the Surin archipelago is still a great place to encounter these noble creatures. Black-tip reef sharks can grow to 1.8m (5.9ft) but more commonly reach a maximum 1.5 -1.6m in length. The single biggest individual on record, weighed in at 13.6kg (30lb). It prefers shallower waters to other reef sharks, most notably the grey and white-tip reef sharks. Its preference for shallower waters, makes it the most commonly seen shark when snorkeling Surin. The best places to find them is along the coral reef ledges, but they do occasionally swim into the shallow sandy flats.

Black tip reef shark - Koh Surin

Blacktip reef shark’s preferred prey species are mullet, groupers, grunters, whitings, jacks and wrassers. They also feed on octopus, cuttlefish, shrimp and squid. Blactip reef sharks, especially the juveniles, tend to fall prey to larger fish. They are preyed upon by tiger sharks, grey reef sharks, groupers and even members of their own species. It’s important to note that sightings of tiger sharks are extremely rare in Thailand, as they prefer cooler waters to the warm waters of Surin.

As a general rule, blacktip reef sharks are harmless to humans, and will never attack you when swimming.

Some care needs to be taken when wading through shallow water however. Blacktip reef sharks can mistake your feet for their natural prey. Keeping your body submerged in water is advised to avoid the extremely unlikely situation whereby a blacktip shark accidentally bites your feet! Rest assured in the knowledge it’s far safer to swim near a blacktip reef shark than walk next to one in shallow water.

Surin Islands
Blacktip Reef sharks - Richelieu Rock

Koh Surin is important habitat for blacktip reef sharks

Juvenile or young blacktip reef sharks often form large groups in very shallow waters not much deeper than their body size. During high tide, they can be found in flooded coral platforms or seaweed beds at Koh Surin and Richelieu Rock. They are fast swimming, and can be found alone or in small groups as adults. Blacktip reef sharks are very territorial and tend to stick to particular areas, often for several years. The Surin islands or Koh Surin as they are also known, are an important nursery for the species. Though not considered a commercially important shark species, they are a common by-catch of Thailand’s coastal fisheries. The consumption of shark meat (particularly their fins) along with their slow reproductive rates, is increasingly threatening the long term survival of this iconic species.

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