Western Indo-Pacific Region
The Western Indo-Pacific comprises the tropical waters of the western and central Indian Ocean. It includes the eastern coast of Africa, the Red Sea, the Gulf of Aden, the Persian Gulf, the Arabian Sea, the Bay of Bengal, and the Andaman Sea, as well as the coastal waters surrounding Madagascar, the Seychelles, the Comoros, the Mascarene Islands, the Maldives, and the Chagos Archipelago. The transition between the Western Indo-Pacific and the Central Indo-Pacific occurs at the Strait of Malacca and in southern Sumatra. The boundary between the Western Indo-Pacific and Temperate Southern Africa realms lies in southern Mozambique, where the southernmost mangroves and tropical corals are found.
Species and subspecies
The dugong (Dugong dugon), is becoming increasingly rare off the coast of East Africa where it was formerly common, except in parts of Mozambique and Tanzania, and will likely disappear except in protected areas. The Red Sea and the Persian Gulf still harbour relatively large numbers, but the species has been all but exterminated in Madagascar and the islands of the western Indian Ocean. A highly isolated breeding population exists in the Marine National Park, Gulf of Kutch, but dugongs have mostly disappeared from the coast of India as well as from the Maldives, Laccadive Islands, and possibly the Andaman and Nicobar Islands as well, except for a few in the Palk Strait between India and Sri Lanka. Another population survives in the Gulf of Myanmar Marine National Park. In Thailand it is mostly restricted to parts of the Andaman Sea coast, with very few now living in the Gulf of Thailand where it was once common.
Two distinct subpopulations of leatherback sea turtle (Dermochelys coriacea) have been recognized in the Western Indo-Pacific. The north-eastern Indian Ocean subpopulation nests primarily in the Andaman and Nicobar Islands, India, Sri Lanka, and to a lesser extent in Thailand and Sumatra. The south-western Indian Ocean subpopulation nests principally along the Indian Ocean coast of South Africa (KwaZulu-Natal), with some nesting in Mozambique. Marine habitats extend around the Cape of Good Hope in both the Indian and Atlantic Ocean.
Four distinct subpopulations of loggerhead sea turtle (Caretta caretta) have been broadly recognized from the Western Indo-Pacific. The north-eastern Indian Ocean subpopulation nests in Sri Lanka. Its marine habitats are assumed to extend throughout a large part of the Bay of Bengal, and possibly beyond. The north-western Indian Ocean subpopulation nests in Oman and Yemen. Its marine habitats extend from the Gulf of Aden to the Arabian Gulf. The south-eastern Indian Ocean subpopulation nests in Western Australia. Its marine habitats extend throughout a wide area including the Timor and Arafura seas. The south-western Indian Ocean subpopulation nests along the south-east African seaboard. Its marine distribution extends throughout a wide area including the Agulhas Current, the southern extend of the Somali Current, and possibly the south-east Atlantic Ocean.
The broad-banded sea snake (Hydrophis mamillaris) is known only from a few specimens collected along the coasts of Pakistan, India and Sri Lanka, the last in 1926. Daudin’s sea snake (H. nigrocinctus) is known only from specimens collected off Bangladesh and southern Myanmar, the last in 1943. Peters’ sea snake (H. bituberculatus) is known only from specimens collected off the coast of south-western Thailand and western Sri Lanka.
The smoothtooth blacktip shark (Carcharhinus leiodon) is known only from a few specimens collected within the coastal waters of the north-western Arabian Sea including the Persian Gulf and Sea of Oman.
The whitetip weasel shark (Paragaleus leucolomatus) is known only from a small number of records off south-eastern, northern Madagascar, and the Comoros Islands. The slender weasel shark (P. randalli) is found sporadically in the coastal waters of the northern Indian Ocean.
The shorttail nurse shark (Pseudoginglymostoma brevicaudatum) is known for certain only from the shallow coastal waters of Kenya, Tanzania, and Madagascar, but may be present off Mauritius and the Seychelles as well. The species was reportedly common during the late twentieth century but has been rarely recorded since, a decline attributed to overfishing and loss of coral reef habitat.
The Comoros catshark (Scyliorhinus comoroensis) is known only from a single specimen collected from deep waters off Grande Comore, in the Comoros Islands, as well as from photographs taken from deep-water submersible surveys.
The bristly catshark (Bythaelurus hispidus) is a deep-water species with a patchy distribution in the northern Indian Ocean, where it is known from coastal Kenya, Oman, southern India, Myanmar, the Andaman Islands, and Socotra Island.
Three species of izak catshark (Holohalaelurus) are potentially threatened by deep-water trawl fisheries. The crying izak catshark (H. melanostigma) is known only from four specimens collected along the eastern coast of Africa. The grinning izak catshark (H. grennian) and the white-spotted izak catshark (H. punctatus) are both known only from a small number of specimens collected along the eastern coast of Africa and the western coast of Madagascar.
The ornate dogfish (Centroscyllium ornatum) is a deepwater species known only from a few specimens collected from the continental slopes of the Arabian Sea and the Bay of Bengal.
Annandale’s guitarfish (Rhinobatos annandalei) is a shark-like ray found patchily along the coast of South Asia from the Arabian Sea to Sri Lanka, where it is threatened by overfishing.
The stripenose guitarfish (Acroteriobatus variegatus) is confined to the continental and insular shelves of western India and Sri Lanka. The grey-spotted guitarfish (A. leucospilus) is confined to the eastern coast of Africa and the western coast of Madagascar. Both are seriously threatened by intense fishing pressure.
The Halavi giant guitarfish (Glaucostegus halavi) is confined to the coastal waters of the north-western Indo-Pacific from the Red Sea to northern India and south to Kenya. It is seriously threatened by overfishing.
The white-spotted wedgefish (Rhynchobatus djiddensis) is found widely across the continental and insular shelves of the Indo-Pacific from the Red Sea and the eastern coast of Africa to Taiwan, the Solomon Islands, and Australia. It is everywhere seriously threatened, however, by intense fishing pressure.
The soft electric ray (Heteronarce mollis) is a rare species known only from a few specimens collected from the northern Indian Ocean off Yemen, Somalia, and southern India.
The tentacled butterfly ray (Gymnura tentaculata) is known only from a few specimens collected along the coast of India. It is threatened by fisheries by-catch.
The bigeye electric ray (Narcine oculifera) is known only from the Sea of Oman and the Gulf of Aden. Riera’s electric ray (N. rierai) is confined to East African coastal waters from Somalia to Mozambique. The Oman electric ray (N. atzi) is known widely but patchily across the northern Indian Ocean. All are threatened by intensive fishing pressure and degradation of their shallow-water habitat.
The Travencore skate (Dipturus johannisdavesi) is a naturally rare species found in deep coastal waters across the northern Indian Ocean. The rattail skate (D. lanceorostratus) and the prownose skate (D. stenorhynchus) both occur patchily along the continental shelf in southern Mozambique and eastern South Africa. All are threatened by shrimp trawl fisheries by-catch.
The Pita skate (Raja pita) is known only from a single specimen collected from the tidal mudflats of the Tigris/Euphrates drainage delta.
Cristina’s skate (Bathyraja tunae) is known only from two specimens collected from deep waters south of Madagascar.
The Madagascar pygmy skate (Fenestraja maceachrani) is known only from a few deep-water localities off north-western Madagascar. The prickly pygmy skate (F. mamillidens) is known only from deep waters off southern India and west of Sri Lanka.
The black legskate (Indobatis ori) is known only from around a dozen specimens collected from deep waters off north-western Madagascar and Bazaruto Island, Mozambique.
The marbled legskate (Anacanthobatis marmoratus) is known only from deep waters off southern Mozambique and north-eastern South Africa (KwaZulu-Natal), where it is threatened by trawl fisheries by-catch.
The African coelacanth (Latimeria chalumnae) is a large, armoured fish often called a ‘living fossil’, belonging as it does to a group that was believed to have become extinct more than 70 million years ago. In 1938 a live specimen was unexpectedly caught off the eastern coast of South Africa. It would not be until 1952 that a second was found, this time in the Comoros Islands. At least one other is known, taken near Grand Comore in 1974. The species is believed to live at moderate depths and to shelter by day in caves. In 1998 the total population was estimated at less than 500.
The white-edged grouper (Epinephelus albomarginatus) appears to be confined to the south-eastern coast of Africa (southern Mozambique and South Africa). The striped-fin grouper (E. posteli) is a naturally rare species known from the south-eastern coast of Africa, Madagascar, and possibly the Mascarene Islands. Both are threatened by overfishing and degradation of their reef habitat.
The Middle East black seabream (Acanthopagrus randalli) is known only from two specimens collected in the Persian Gulf and a photo taken off the coast of south-western Pakistan.
The Karanteen seabream (Crenidens macracanthus) is known only from two specimens collected during the nineteenth century off Pakistan and India.
The Mascarene seabream (Polysteganus mascarenensis) is known only from three specimens collected from the western Indian Ocean.
The Ganges seabream (Sparidentex datnia) is known only from the mouth of the Ganges River in north-eastern India and Bangladesh.
The backlash scorpionfish (Pontinus nigerimum) is known only from a few specimens collected from the south-eastern coast of South Africa, the southern coast of Madagascar, and the Mascarenes.
The Cocos pufferfish (Tetraodon implutus) is known only from specimens collected in the 1830s from HMS Beagle survey near the Cocos Islands, south-west of Sumatra. Its taxonomic validity has been questioned.
The banded leopard pufferfish (Arothron leopardus) is known only from a single specimen collected off the southern coast of India in 1878.
The Andaman sharpnose pufferfish (Canthigaster investigatoris) is known only from two specimens collected in 1910 off of the Andaman Islands.
The jewelled tang (Zebrasoma gemmatum) is a rare species from the deeper coastal waters of south-eastern Africa, Madagascar and the Mascarenes. It is harvested for use in the international aquarium trade.
The multibar surgeonfish (Acanthurus polyzona) occurs in along the coast of Madagascar and within the Mascarene and Comoros islands, where it may be threatened by degradation of its coral reef habitat.
The western Indo-Pacific toadfish (Allenbatrachus meridionalis) is a freshwater and marine species known only from a few specimens collected from Madagascar and the island of Réunion.
The striped boga (Boops lineatus) is confined to coastal areas of the eastern Arabian Peninsula.
The Madagascar kob (Argyrosomus hololepidotus) is confined to estuaries and mangroves on the south-eastern coast of Madagascar, where it is threatened by overfishing.
The red-tipped halfbeak (Hyporhamphus xanthopterus) is confined to a few brackish lakes and estuaries in south-western India (Kerala).
Whitehead’s gizzard shad (Gonialosa whiteheadi) is known only from two specimens collected from an estuary in southern Myanmar.
Valenciennes’ razorfish (Iniistius cyanifrons) is known only from coastal southern India off Pondicherry and Madras.
Rajagopalan’s razorfish (Xyrichtys rajagopalani) is known only from its original collection during the 1980s along coastal south-western India.
The purple-lined wrasse (Choerodon gymnogenys) is found along the East African coast from Kenya to Mozambique, including the waters around Zanzibar. It is likely threatened by overfishing.
The largescale wrasse (Decodon grandisquamis) is known only from coastal southern Mozambique.
The rosy-scaled fairy-wrasse (Cirrhilabrus rubrisquamis) is known only from the waters around Sri Lanka, the Maldives, and the Chagos Archipelago, where it is threatened by degradation of its coral reef habitat and collection for the international aquarium trade.
The four-line wrasse (Larabicus quadrilineatus) is confined to the Red Sea and the Gulf of Aden. It is possibly threatened by overcollection for the international aquarium trade.
The western Indo-Pacific lined wrasse (Pseudocheilinus dispilus) is known only from eastern coastal Madagascar and off the islands of Mauritius and Réunion.
Day’s goby (Scartelaos cantoris) is known only from three specimens collected in the Andaman Islands in the 1870s.
The South Cinque combtooth blenny (Alloblennius frondiculus) is known only from a single specimen collected from South Cinque Island, in the Andaman Islands.
The Andaman combtooth blenny (Andamia expansa) is known only from its original collection in the Andaman Island in the mid-nineteenth century.
The mud blenny (Parablennius lodosus) is known only from Delagoa Bay, central Mozambique, where it is threatened by periodic dredging, pollution, and coastal development.
The Mekran combtooth blenny (Omobranchus mekranensis) is known only from a few scattered records from coastal areas of the Persian Gulf, Gulf of Oman, and northern Arabian Sea, where it is potentially threatened by oil spills.
The estuary catfish (Ayarnangra estuarius) is known only from a few specimens collected from the tidal reaches of the lower Irrawaddy River.
Kotthaus’ cucumberfish (Paraulopus maculatus) is a cylindrical-shaped species known only from a single specimen collected in the 1960s off Mombasa, Kenya.
Bruce’s pugheaded pipefish (Bulbonaricus brucei) is known only from a few specimens collected from coral reefs off the coast of Tanzania.
The dwarf pipefish (Campichthys nanus) is known only from a few specimens collected during the 1970s from coastal northern Mozambique. Records from the South China Sea are based on misidentifications.
The Mascarene Plateau
The Mascarene Plateau is a submarine plateau in the northwestern Indian Ocean, north and east of Madagascar. It extends approximately 2000 km from the Seychelles in the north to Réunion in the south. Mainly shallow (8–150 m over most of its area), it plunges to a depth of 4000 m in the abyssal plain at its edge.
The Mascarene sharpnose pufferfish (Canthigaster punctata) is known only from a few specimens collected from the Mascarene Plateau.
The Réunion angelfish (Apolemichthys guezei) is known only from deep-water reef slopes off Réunion.
The yellow slender wrasse (Pseudojuloides xanthomos) is known only from a single specimen collected off Mauritius.
Pelicier’s wrasse (Halichoeres pelicieri) is confined to deepwater reef slopes off Mauritius.
The green wrasse (Anampses viridis) is known only from a single specimen collected off Mauritius in the early nineteenth century.
Guichenot’s goby (Cotylopus acutipinnis) is a freshwater and marine species confined to Mauritius and Reunion.
The Réunion combtooth blenny (Mimoblennius lineathorax) is confined to shallow rocky reefs off western Réunion.
The Mascarene weedfish (Springeratus polyporatus) is known only from tidepools and nearshore subtidal areas on Mauritius and Réunion, where it is threatened by coastal development.
The Seychelles Bank
The Seychelles Bank is located on the northern part of the Mascarene Plateau.
The Seychelles gulper shark (Centrophorus seychellorum) is known only from two specimens collected from deep waters off Alphonse Island in the Seychelles.
The Seychelles spurdog (Squalus lalannei) is a deep-water species known only from two specimens collected off Alphonse Island in the Seychelles.
The Chagos–Laccadive Ridge
The Chagos–Laccadive Ridge is a vast volcanic ridge and oceanic plateau extending between the northern and central Indian Ocean. It includes the Laccadive, Maldives, and Chagos archipelagos.
The Maldives wrasse (Frontilabrus caeruleus) is known only from a single specimen collected from the Maldives in the 1980s.
The South Malé triplefin blenny (Helcogramma maldivensis) and the North Malé triplefin blenny (H. larvata) are each known only from a few specimens collected from two small atolls in the Maldives in 1992.
The Maldives righteye flounder (Poecilopsetta albomaculata) is known only from a few specimens collected in the waters around the Maldives.
The Laccadive eel (Xenomystax trucidans) is known only from a few specimens collected from deep waters in the Maldives and Laccadives.
The Red Sea
The Red Sea is a seawater inlet of the Indian Ocean lying between Africa and Asia. The world’s northernmost tropical sea, its connection to the ocean is in the south through the Gulf of Aden. It has an average depth of 490 m, a maximum depth of 3040 m, and features extensive shallow shelves noted for their marine life and corals.
The Red Sea torpedo ray (Torpedo suessii) is known only from a single specimen collected in 1898 off the coast of Yemen. It is possibly extinct, a victim of fisheries by-catch.
The Red Sea thicklip wrasse (Hemigymnus sexfasciatus) is known only from a couple of records originating in the Red Sea.
The lonely blenny (Entomacrodus solus) is known only from the Ras Mohammed Marine Park, off the southern tip of the Sinai Peninsula, Egypt.
Steinitz’s combtooth blenny (Omobranchus steinitzi) is known only from four specimens collected from a single locality in the Dahlak Archipelago, in the southern Red Sea.
The Marsa el At combtooth blenny (Adelotremus leptus) is known only from a single specimen collected from the northwestern Red Sea.
The Red Sea roughy (Hoplostethus marisrubri) is known only from five specimens collected from a single locality (possibly a seamount) in the middle of the Red Sea.
The Hurghada pipefish (Syngnathus macrophthalmus) is confined to the north-western Red Sea.
The Gulf of Aqaba
The Gulf of Aqaba (Khalij al-Aqabah in Arabic) is a large gulf located at the northern tip of the Red Sea, east of the Sinai Peninsula and west of the Arabian mainland.
The Eilat sleeper ray (Heteronarce bentuviai) is a rare, deep-water species known only from the Gulf of Aqaba.
The pale dottyback (Pseudochromis pesi) is known only from the Gulf of Aqaba.
The Eilat cardinalfish (Gymnapogon melanogaster) is known only from two specimens collected in the Gulf of Aqaba.
The wreck pipefish (Syngnathus safina) is known only from a single locality off the Jordanian coast in the Gulf of Aqaba.
The Gulf of Suez
The Gulf of Suez (Khalig as-suwais in Arabic) is located at the northern end of the Red Sea, to the west of the Sinai Peninsula.
Russell’s slender wrasse (Suezichthys russelli) is known only from a few specimens collected in the Gulf of Suez.
The Arabian Sea
The Arabian Sea (Bahr Al-Arab in Arabic) is a region of the north-western Indian Ocean bounded on the north by Pakistan and Iran, on the west by the Gulf of Aden and the Arabian Peninsula, and on the east by India. The Gulf of Aden connects it to the Red Sea in the west, while the Gulf of Oman connects it to the Persian Gulf in the north-west.
The Oman bullhead shark (Heterodontus omanensis) is known only from two localities off Pakistan and Masirah Island, Oman.
The Indian swellshark (Cephaloscyllium silasi) is a small (perhaps dwarf ) bottom-dwelling species known only from the coast of Kerala.
The harlequin catshark (Ctenacis fehlmanni) is known only from a single specimen collected off the coast of Somalia.
The Arabian catshark (Bythaelurus alcockii) is known only from a single (now lost) specimen collected off the coast of Pakistan.
The speckled catshark (Halaelurus boesemani) is known only from a few specimens collected off the coast of Somalia.
The Salalah guitarfish (Acroteriobatus salalah) is known only from the coasts of Oman and Pakistan.
The Quilon electric ray (Heteronarce prabhui) is known only from a single specimen collected off south-western India.
The reversed skate (Amblyraja reversa) is known only from a single specimen collected off the coast of Pakistan.
The Somali grouper (Epinephelus indistinctus) is known only from the coastal waters of Oman and northern Somalia.
The black-margined seabream (Acanthopagrus omanensis) is known only from a few specimens and observations from the coast of central Oman.
The Dhofar parrotfish (Scarus zufar) is known only from rocky reefs off the coast of Oman.
The Oman dottyback (Pseudochromis omanensis) is known only from coastal Oman and the Socotra Archipelago. It is occasionally collected for the aquarium trade.
The blackbar coris (Coris nigrotaenia) is a type of wrasse known only from the waters of coastal Oman and Masirah Island.
The slant-band wrasse (Thalassoma loxum) is known only from a few specimens collected in shallow waters off Oman and Socotra Island.
The sign wrasse (Halichoeres signifer) is confined to shallow waters off the coast of Oman. The Sawda wrasse (H. melas) is known only from a few specimens collected from Sawda Island off the coast of southern Oman.
The Oman blenny (Oman ypsilon) is known only from coastal Oman. While not uncommon, it is potentially threatened by oil spills.
The Astola combtooth blenny (Antennablennius velifer) is known only from tidal areas on Astola Island.
Herring’s searsid (Normichthys herringi) is a type of deepsea smelt known only from two specimens collected within the Arabian Sea.
The Arabian Sea flagtail pipefish (Doryrhamphus aurolineatus) is known only from two specimens collected off Masirah Island, Oman.
The Persian Gulf
The Persian Gulf (Xalij-e Fars in Persian) is an extension of the Indian Ocean (Gulf of Oman) by way of the Strait of Hormuz, and lies between Iran to the north-east and the Arabian Peninsula to the south-west. The Shatt al-Arab river delta forms the north-west shoreline. The gulf is heavily fished and has extensive reefs (mostly rocky, but also of coral). It has been severely degraded by industrialization and oil spills.
The Persian mullet (Liza persicus) is known only from a few specimens collected in the shallow coastal waters of Qatar and Bahrain.
Randall’s goatfish (Upeneus randalli) is known only from two specimens collected in the coastal waters of Kuwait and Bahrain.
The convict zebra sole (Zebrias captivus) is known only from two specimens collected off the coast of Bahrain.
Stanaland’s sole (Solea stanalandi) is known only from a few specimens collected in the Persian Gulf.
The Persian Gulf eel goby (Taenioides kentalleni) is known only from a single specimen collected in Ras Az Zawr Bay, Saudi Arabia.
The onespot goby (Coryogalops monospilus) is known only from a single specimen collected from a rock pool in coastal Kuwait.
The Gulf of Aden
The Gulf of Aden is a deep-water gulf located between Yemen to the north, the Arabian Sea to the east, Djibouti to the west, and Somalia to the south.
Philip’s skate (Okamejei philipi) is a poorly known species from the Gulf of Aden.
The Andaman Sea
The Andaman Sea (historically also known as the Burma Sea) is a marginal sea of the eastern Indian Ocean. It is separated from the Bay of Bengal by the Andaman and Nicobar Islands, and is bounded to the north and east by Myanmar and the northern part of the Malaysian Peninsula. Its southernmost limit is defined by Breueh Island, located just north of Sumatra.
The Burmese bambooshark (Chiloscyllium burmensis) is known only from a single specimen collected in 1963 off the coast from Rangoon.
The Andaman legskate (Cruriraja andamanica) is known for certain only from a handful of specimens collected from the Andaman Sea.
The Bay of Bengal
The Bay of Bengal is located in the north-eastern part of the Indian Ocean. It is bounded on the west and north-west by India, on the north by Bangladesh, and on the east by Myanmar and the Andaman and Nicobar Islands. Its southern limit is a line between Sri Lanka and the north-westernmost point of Sumatra.
The collared sea snake (Hydrophis stricticollis) historically occurred in the coastal waters of the Bay of Bengal from Sri Lanka to Myanmar. It has not been recorded from India since 1943, and was last reported from Bangladesh in 1991.
The broadnose catshark (Apristurus investigatoris) is a small, deep-water species known only from a single specimen collected from the Bay of Bengal.
The Bengal yellowfin seabream (Acanthopagrus longispinnis) is known only from two localities in the north-western Bay of Bengal.
The Chaptis bahaba (Bahaba chaptis) is confined to the coastal waters of the Bay of Bengal, where it is taken as bycatch.
The Bay of Bengal lizardfish (Saurida pseudotumbil) is known only from a few specimens collected from the eastern coast of India.
The Hooghly Estuary
The Hooghly Estuary is located in north-eastern India (West Bengal).
The smoothback guitarfish (Rhinobatos lionotus) is known only from the mouth of the Hooghly River.
The Hooghly halfbeak (Dermogenys brachynotopterus) is known only from a single specimen collected from the Hooghly Estuary in the mid-nineteenth century.
The Mozambique Channel
The Mozambique Channel (Canal du Mozambique in French/Canal de Moçambique in Portuguese) is located between Madagascar and south-eastern Africa. The warm Mozambique Current flows through it in a southward direction into the Agulhas Current off the eastern coast of South Africa.
The broadhead catshark (Bythaelurus clevai) is known only from a few specimens collected from deep waters off the coast of south-western Madagascar.
The Madagascar electric ray (Narcine insolita) is known only from coastal south-western Madagascar.
The Madagascar skate (Dipturus crosnieri) is a rare deepwater species known only from south-central coastal Madagascar.
The Madagascar cardinalfish (Foa madagascariensis) is known only from two specimens, now lost, collected off the coast of south-western Madagascar in the early 1930s.
Anthropogenic effects on the fauna
Within the Western Indo-Pacific Region at least 1 species of marine fish is possibly extinct. In addition, there are 132 species currently threatened with extinction (that is to say, either Critically Endangered, Endangered, or Vulnerable according to the IUCN Red List, as well as certain forms either listed as Data Deficient or Not Assessed but which are clearly at some risk of extinction). Of these, 3 species are reptiles, and 129 species are marine fishes.