The Oceanic Realm
The world’s oceans, which cover approximately 70 per cent of the Earth’s total surface area, are for the purposes of this website considered to be a single interconnected realm, divided into 10 regions. Most ocean life lives near the surface and in particular along the continental and insular shelves. The latter offer a wide range of habitats including tidal pools, coral reefs, and kelp forests.
Species and subspecies
The blue whale (Balaenoptera musculus), at up to 30 m in length and weighing upwards of 173 metric tonnes, is the largest animal known to have ever existed. While some dinosaurs may have been longer, none were heavier. The species was abundant in nearly all the oceans of the world until the beginning of the twentieth century, when it began to be hunted almost to extinction by whalers. Officially protected by the international community now for more than half a century, today it is thought that there are between 10,000 and 25,000 worldwide, divided into at least three well-marked subspecies. This is still down considerably from pre-whaling days, when there were some 200,000 or 300,000 in the Southern Ocean alone, but is nevertheless encouraging. The northern blue whale (B. m. musculus) occurs in both the North Atlantic as well as in the northern and eastern Pacific. It is found throughout the former (although not in the Mediterranean), summering in temperate to subarctic waters and migrating further south in winter. In the Pacific it is quite common along the California coast and the Baja California region as well as across the North Pacific from the coast of Oregon to the Kuril Islands and north to the Aleutians, but does not extend far into the Bering Sea. Blue whales were historically caught off southern Japan and the Korean Peninsula, but have not been reported there in many years. The Antarctic blue whale (B. m. intermedia) is the largest subspecies. Not surprisingly it was consequently a prime target for whalers, and it is estimated that the total historical kill was about 350,000. The most recent circumglobal population estimate was just 2280 in 1998. The short-tailed blue whale (B. m. brevicauda) has a range centred in the Indian Ocean north of 52°S. It occurs around Madagascar, the Seychelles, and the inshore waters of Kenya, across the pelagic southern Indian Ocean (especially around Prince Edward Island and the Crozet and Kerguelen islands), and off South Australia and Western Australia, where it forms part of a more or less continuous distribution from Tasmania to Indonesia. It may occur off New Zealand as well. Blue whales appear to be rare or absent in the central or South Pacific between New Zealand and a population along the coast of Chile is of undetermined taxonomy. In terms of migration they appear to move southwards during the austral summer. The subspecies was nominally given total protection in 1966 but continued to be heavily hunted for decades afterwards, in particular by Soviet whalers, with a known catch of over 9500 during the period 1960–72. There is currently no comprehensive estimate available for total population size, but it is thought that it has recovered somewhat and does not remain as severely depleted as the Antarctic blue whale. The Indian Ocean blue whale (B. m. indica), possibly synonymous with the pygmy blue whale, occurs in the northern Indian Ocean, where a large colony was discovered off Sri Lanka after the end of the 30-year civil war.
The fin whale (B. physalus), the second largest species of whale, is noted for its slender, streamlined body which allows it to surpass the speed of even the fastest ocean ships. At least two subspecies are recognized. The North Atlantic fin whale (B. p. physalus) occurs in the North Atlantic, North Pacific, and Arctic oceans, while the southern fin whale (B. p. quoyi) occurs throughout the colder waters of the southern hemisphere.
The sei whale (B. borealis) is a migratory species that occurs throughout the world’s oceans, where it prefers deeper offshore waters and avoids both tropical and polar regions. During the large-scale commercial whaling period during the late nineteenth and twentieth centuries over 255,000 were killed. Protected since the 1970s, in 2008 the total population was estimated at around 80,000.
Omura’s whale (B. omurai) is known only from a small number of sightings and strandings throughout the tropical oceans of the world.
The sperm whale (Physeter macrocephalus), the largest of all toothed predators, is found throughout the world’s oceans, migrating seasonally for feeding and breeding. Prior to the early eighteenth century it was hunted mostly by indigenous Indonesians for food, but from then on into the twentieth century it became a target of the organized whaling industry primarily for its spermaceti and sperm oil, which were used in oil lamps as well as in candles, soaps, cosmetics, and lubricants. The whale’s ivory-like teeth were also much sought for use in inked carvings known as scrimshaw, as was ambergris, a solid, waxy substance present in the digestive system [the latter is still highly valued today as a fixative in perfumes, and is generally obtained by lucky beachcombers]. At first the Americans hunted it off New England, as depicted in the novel Moby Dick, using small sloops carrying only one or two open whaleboats, and then more widely throughout the Atlantic. Hunting was dangerous work, as the whales (especially bulls) would readily defend themselves against the harpoon-throwing crews by using their huge head effectively as a battering ram. Perhaps the most famous such instance occurred on 20 November 1820, when a whale alleged to be about 26 m in length rammed and sank the Nantucket whaleship Essex. The size of the whaling ships and the scope of the fleet continued to increase over time, and by the 1770s were producing some 45,000 barrels of sperm oil annually Eventually the British and later the French entered the trade. The slaughter continued to increase until the mid-nineteenth century, at which point the hunt had become global and ever-more efficient, employing steam-powered ships and exploding harpoons. It gradually declined thereafter as petroleum came into broader use, but by then, as with other large whales, the species had been nearly driven to extinction. Relief finally came when bans on whale oil were instituted in 1972. The International Whaling Commission gave the sperm whale full legal protection in 1985, although hunting by Japan in the northern Pacific continues on a small scale to this very day. The species is gradually recovering, although individuals are still threatened by fishing nets and ship collisions.
The bowhead whale (Balaena mysticetus) was also a preferred whaling target and was severely reduced in number before the 1966 moratorium. While some subpopulations remain small, the species is no longer considered to be threatened.
The North Atlantic right whale (Eubalaena glacialis) was probably the species that, historically, constituted the largest part of the global whaling catch, and was hunted almost to extinction. It was once abundant on both sides of the Atlantic, where it was chiefly found along the coasts of arctic lands and was therefore particularly vulnerable. It was already being hunted in the Bay of Biscay in the eleventh century, and this would develop into an industry that was to continue for five centuries, expanding into the northern Atlantic. By 1611 whalers were going out specifically in search of it (hence the name ‘right’ whale). Dutch vessels took almost 7000 of them in the Davis Strait and Disko Bay between 1719 and 1788, and during another period, 1814–16, a fleet of 586 British vessels caught 5000 whales on the west coast of Greenland. At the beginning of the eighteenth century numbers began to dwindle in the eastern North Atlantic, and by the early nineteenth century it was, for a time, believed to be extinct. By the beginning of the twentieth century it had largely disappeared everywhere and reports were few and far between. Finally, in 1929, even the Norwegians had abandoned hunting it, but it would not be until 1937 that the species was given protection throughout the arctic. The only exception to the prohibition was local hunting by Inuit, which has since mercifully stopped. But whales take a long time to recover their numbers, if ever. Today there are still only about 400 individuals in the western North Atlantic, migrating between feeding grounds in the Labrador Sea and their winter calving ground off Georgia and Florida – an area of ocean with heavy shipping traffic. In the eastern North Atlantic, where it once ranged from the Norwegian Sea through the western British Isles and the Azores to its calving ground off Western Sahara, the total population is in the low teens at best, and it is thought that the species may be functionally extinct there. Vessel strikes and entanglement in fixed fishing gear are now the primary causes of mortality.
The southern right whale (Eubalaena australis) historically occurred in large numbers over a vast area of the southern oceans. As we have seen, by 1750 the North Atlantic right whale (E. glacialis) was as good as extinct for commercial purposes, and so it was that American whalers began to move first into the South Atlantic before ultimately spreading into the Southern and Pacific oceans, where they were joined by fleets from several European nations. This heavy hunting resulted in the decline of all whale populations, and this species was particularly hard hit. While it is difficult to know for certain, there can be no doubt that hundreds of thousands were killed during the nineteenth and twentieth centuries. When it had become obvious that the southern right whale was becoming extinct a complete ban on harpooning it came into effect in 1937, which was mostly successful despite continued illegal whaling by the Soviets and others. By the 1950s and 1960s the species began to reappear in areas where it had been long extirpated, for example, around Tristan da Cunha and South Georgia. The total current population is thought to be around 10,000.
The humpback whale (Megaptera novaeangliae), like other large whales, was a favourite target for the whaling industry. Once hunted to the brink of extinction, its global population fell by an estimated 90 per cent before a 1966 moratorium. The species has since recovered and is no longer considered threatened, although entanglement in fishing gear, ship collisions, and noise pollution continue to affect individuals.
The grey whale (Eschrichtius robustus) nowadays has a very limited distribution within the shallow coastal waters of the North Pacific and adjacent Arctic Ocean, where it is considered to be reasonably abundant although extremely vulnerable to exploitation. It is interesting to note that the species formerly occurred in the North Atlantic as well. Subfossil remains, the most recent dating to around 1675, have been discovered on the eastern seaboard of the United States from Florida to New Jersey, on the coasts of the English Channel, and in the North and Baltic seas. There are historical accounts of living grey whales from Iceland in the early 1600s and possibly off New England in the eighteenth century, after which they are presumed to have been extirpated. Twice during the nineteenth century the species had very nearly been exterminated. In the eastern North Pacific it was rapidly depleted by commercial whalers after its wintering concentrations in the lagoons along the Baja California Peninsula in Mexico were discovered. Peak catches, averaging over 480 per year, occurred between 1855 and 1865. Lagoon whaling ended by around 1875, apparently due to the exhaustion of populations, but shore-based whaling in California continued at low levels until the late nineteenth century. During the twentieth century there were some pelagic catches off California and Mexico by Norwegian and American vessels in the 1920s and 1930s, and in the 1930s and 1940s by the Soviet fleet in the Bering and Chukchi seas. A further 320 were taken under scientific permit during the 1960s, and at least 138 illegal Soviet catches occurred in that decade as well. The species has been more or less successfully protected since then, although sadly ‘aboriginal subsistence’ whaling resumed within the Bering and Chukchi seas in 1948 and has continued up to the present at the rate of more than 100 kills per year. Small numbers have also been taken by aboriginal whalers in Alaska and by the Makah tribe in Washington state. Nevertheless, the population has recovered overall, and the species is not presently considered threatened. A few rare reports of grey whales well outside their normal range have been documented in recent years. In 2010 one was observed in the Mediterranean Sea off Israel, and a few days later again off Spain. That same year another was found stranded on the coast of El Salvador, and in 2013 off Namibia. This perhaps suggests that the species may be reclaiming areas from which it was formerly extirpated.
The northern or North Atlantic bottlenose whale (Hyperoodon ampullatus) is one of the deepest-diving mammals known, capable of reaching depths of 2339 m and staying underwater for up to 130 min. A North Atlantic endemic, it was one of the few species of beaked whale to be hunted commercially on a large scale. Both Norway and Britain did so from the 1850s to the 1970s, taking over 65,000 whales with many more struck and lost. The species has also been cruelly hunted in Faroe Island drive fisheries, and remains depleted to this day. High levels of anthropogenic sound, especially from military sonar and seismic surveys, are an additional threat.
The spade-toothed beaked whale (Mesoplodon traversii) is considered to be the rarest of the beaked whales, and was long known only from a partial jaw found washed ashore on Pitt Island, New Zealand in 1872. Two other skull fragments were discovered during the 1950s at White Island, also in New Zealand, and on Robinson Crusoe Island off Chile in 1993. It was not until 2010 when two individuals (a cow and her calf ) were found stranded on Opape Beach on the northern coast of North Island, New Zealand that the species was at last observed alive. Arguably the least-known large mammal on Earth, it appears to be confined to remote temperate waters of the southern Pacific. The ginkgo-toothed beaked whale (M. ginkgodens) is known from fewer than 20 strandings within the Indian and Pacific oceans, specifically on the coasts of Japan, California, the Galápagos Islands, New South Wales, New Zealand, Sri Lanka, the Maldives, and in the Strait of Malacca and the South China Sea. There are no confined live sightings at sea. Andrew’s beaked whale (M. bowdoini) is only known from around 35 specimens washed up on beaches in Australia, New Zealand, the Falkland Islands, and Tristan da Cunha. Never observed in the wild, it is thought to have a circumpolar distribution within the temperate waters of the Southern Hemisphere.
Shepherd’s beaked whale (Tasmacetus shepherdi) is known only from a small number of at-sea sightings and a few dozen strandings in the temperate waters of New Zealand, Argentina, Tristan da Cunha, Australia, and the Juan Fernández Islands.
Arnoux’s beaked whale (Berardius arnuxii) is a naturally rare species from deep, cold temperate and subpolar seas.
Burmeister’s porpoise (Phocoena spinipinnis) is widely distributed in the coastal waters of South America from southern Brazil south to Cape Horn in Tierra del Fuego, north to northern Peru. Up until the late 1990s it, along with other small cetacean species, was extensively hunted in Chile and Argentina by crab fishermen for use as bait. However, it is in Peru that the major threat to this species occurs today, in the form of gillnet by-catch and, to a lesser extent, hunting for meat.
The Indo-Pacific finless porpoise (Neophocaena phocaenoides) is found in the shallow coastal waters as well as river mouths and estuaries of the southern and south-eastern Asian coasts. It is threatened by fisheries by-catch, habitat destruction, boat traffic, and pollution.
The Irrawaddy dolphin (Orcaella brevirostris) is a small, euryhaline species found in discontinuous subpopulations along the coasts of the Bay of Bengal and South East Asia, where it favours shallow marine waters as well as brackish estuaries and freshwater river mouths. It is threatened mainly by fisheries by-catch.
The franciscana dolphin (Pontoporia blainvillei) is confined to the shallow coastal waters of Brazil, Uruguay, and Argentina, where it occasionally enters the estuary of the La Plata River. The species is considered threatened due to accidental mortality in gillnets.
The dugong (Dugong dugon) is a relatively small, herbivorous marine mammal whose closest relative is the now-extinct Steller’s sea cow (Hydrodamalis gigas). It is found sporadically across the Western and Central Indo-Pacific in warm, shallow coastal and inland waters from East Africa in the west to the Solomon Islands and New Caledonia in the east, where it is largely dependent upon seagrass for subsistence. The animals have been hunted for thousands of years for their meat and oil, and have consequently either been extirpated or are close to extinction almost everywhere. Few vertebrate groups are as much in danger as are the sea turtles. While still fairly common as a group they are broadly divided into smaller genetic subpopulations, and in addition are migratory and entirely dependent upon their tropical sandy nesting beaches for their survival. Permanent protection of these strategically important beaches is thus vital, and all species must therefore be considered ‘conservation-dependent’.
The leatherback sea turtle (Dermochelys coriacea) is the largest living turtle and the fourth heaviest reptile (behind three crocodilians), and is easily differentiated from other sea turtles by its lack of a bony shell, hence the name. The species also has the widest distribution of the sea turtles, being found in all tropical and subtropical oceans of the world and ranging as far north as Alaska and Norway and as far south as Cape Agulhas in Africa and the southernmost tip of New Zealand. However, the global population is separated into seven distinct subpopulations, which will be discussed within their respective regions based upon their nesting sites.
The green sea turtle (Chelonia mydas) occurs throughout the tropical and, to a lesser extent, subtropical waters of the world, where it is highly migratory. Two distinct subpopulations are recognized here, each with its own separate nesting and feeding grounds. The Atlantic Ocean subpopulation is discussed under the Tropical Atlantic Region. The Indo-Pacific subpopulation ranges as far north as the southern coast of Alaska, Japan, and the southern parts of Russia’s Pacific coast, and as far south as Chile and the northern tip of New Zealand and a few islands south of Tasmania. It is also found throughout the Indian Ocean. Significant nesting grounds are scattered throughout the warmer parts of both oceans, including Mexico, the Hawaiian Islands, islands of the South Pacific, the northern coast of Australia, South and South East Asia, islands of the western Indian Ocean, and the eastern coast of Africa.
The hawksbill sea turtle (Eretmochelys imbricata) is similarly distributed in the tropical and subtropical oceans of the world, where it is generally divided into two subspecies. The Atlantic hawksbill (E. i. imbricata) is discussed under the Tropical Atlantic region. The Indo-Pacific hawksbill (E. i. bissa) can be further divided into two subpopulations. The Indo-Pacific subpopulation ranges from the eastern coast of Africa and Madagascar, the Persian Gulf and Red Sea, along the southern coast of Asia through the Malay Archipelago and into the western Pacific from the tips of the Korean Peninsula and Japanese Archipelago south to northern New Zealand and east to the Hawaiian and Galápagos Islands. Major nesting sites are to be found on various islands in the Indian Ocean, peninsular Malaysia, Borneo, southern New Guinea, and the northern coast of Australia. The Eastern Pacific subpopulation occurs sporadically from the Baja California Peninsula south along the coast to southern Peru. Important remnant nesting and foraging sites are found in Mexico, El Salvador, Nicaragua, and Ecuador. It is interesting to note that unlike hawksbills elsewhere in the world, which have a preference for coral reefs, those in the Eastern Pacific favour mangroves and estuaries.
The loggerhead sea turtle (Caretta caretta) is another circumglobal species. Ten distinct subpopulations are recognized, which will be discussed under their respective (bio)regions.
The olive ridley sea turtle (Lepidochelys olivacea) is a small species found throughout the tropical oceans of the world. The most abundant of all sea turtles, it is famous for its mass nesting behaviour (known as arribada), whereby thousands of females will come together on the same beach to lay their eggs. As such, it is highly vulnerable to egg harvest and hunting.
Kemp’s ridley sea turtle (Lepidochelys kempii) is the smallest and most seriously endangered of all the sea turtles. Its range mainly consists of the subtropical and tropical waters of the eastern Atlantic and the Gulf of Mexico, although it can be found as far north as New Jersey and stragglers have been reported off the coast of Ireland and Devon. However, almost all females return each year to nest on a single beach (Rancho Nuevo), in the Mexican state of Tamaulipas, where they were historically hunted to the point of depletion. In recent years the species has begun to nest more frequently on beaches in the coastal islands of south Texas. While still killed illegally in Mexico for use as boot material and as food, today the more urgent threats are loss of habitat, pollution, and entanglement in shrimping nets.
Wall’s sea snake (Hydrophis walli) and the plain sea snake (H. inornatus) are each known only from a single specimen collected during the nineteenth century from somewhere in the Indo-Pacific.
The whale shark (Rhincodon typus) is the largest species of extant fish. While still found in open tropical waters the world over the species is threatened by commercial fishing, by-catch in nets, and vessel strikes.
The basking shark (Cetorhinus maximus) is the second largest living shark and can be found in all of the world’s temperate oceans. Long exploited for its meat and fins, it has been extirpated in some areas and severely reduced in many others.
The megamouth shark (Megachasma pelagios) is a naturally rare plankton-eating species found worldwide in tropical seas. Only around 120 have been recorded since its discovery in 1976, although based on its wide range and generally limited interactions with fisheries it is not considered to be threatened.
The porbeagle (Lamna nasus) is a large shark with a disjunct, anti-tropical distribution, occurring in the northern Atlantic as well as circumglobally in the southern hemisphere in cooler temperate waters. It is heavily fished everywhere for its high-value meat and frequently targeted for its fins.
The great white shark (Carcharodon carcharias) can be found in almost all coastal and offshore waters with a temperature between 12 and 24°C, with the greatest concentrations occurring in the United States (north-east and California), South Africa, Japan, Oceania, Chile, and the Mediterranean. Notable for its enormous size, it has no natural enemies apart from (very rarely) killer whales, but its reputation as a maneater has led to persecution in some areas, in particular Australia and South Africa. After having undergone a considerable decline during the late twentieth century it has recently shown signs of increasing thanks to greater legal protection.
The sand tiger shark (Carcharias taurus) is found widely but patchily in coastal subtropical and temperate waters worldwide, but is everywhere declining due to commercial overfishing, spearfishing, and protective beach meshing.
The smalltooth shark (Odontaspis ferox) is found extensively, although sporadically, in tropical and warm temperate coastal waters worldwide. However, apart from a handful of dive localities it is rarely seen and appears to be naturally rare.
Several requiem sharks of the genus Carcharhinus are seriously threatened by overfishing for their meat and fins, and to a lesser extent for their hide, liver oil, and jaws. The oceanic whitetip shark (C. longimanus) is a large pelagic species that was, historically, perhaps the world’s most abundant large animal. While still found in deep, open tropical and warm temperate waters throughout the Oceanic Realm, it has undergone an almost complete loss of its former numbers. The silvertip shark (C. albimarginatus) is another large species usually encountered around offshore islands and coral reefs within the tropical Indo-Pacific. The Pondicherry shark (C. hemiodon) historically ranged along the continental and insular shelves of the Indo-Pacific from the Arabian Sea to the South China Sea and south through Indonesia. Only a small number of specimens have ever been collected, however, and all prior to 1960. The dusky shark (C. obscurus) is found patchily in coastal waters throughout the world, where it is highly vulnerable to fisheries. The sandbar shark (C. plumbeus) is found over muddy or sandy bottoms in shallow coastal waters of the Atlantic and Indo-Pacific. The spinner shark (C. brevipinna), so-named for the spinning leaps it makes as part of its feeding strategy, occurs in tropical and warm temperate coastal waters worldwide except for the eastern Pacific. The night shark (C. signatus) is a deep-water species widely distributed along the outer continental shelves and upper continental slopes of the Atlantic from the north-eastern United States to Argentina in the west, including the Gulf of Mexico and the Caribbean, and from Senegal to northern Namibia in the east. Generally uncommon, it is commercially targeted in some areas for its highly prized fins. The silky shark (C. falciformis) is found worldwide in tropical waters.
Mako sharks (Isurus) are relatively large, reaching about 4 m in length. The longfin mako shark (I. paucus) and the shortfin mako shark (I. oxyrinchus) are each found worldwide in temperate and tropical waters, where they are generally uncommon. Both are considered to be of limited commercial value as their meat and fins are of lower quality than those of other pelagic sharks, but are nevertheless caught unintentionally in low numbers as by-catch.
Thresher sharks (Alopias) are large and notable for their greatly elongated caudal fins. Despite their imposing features they are only minimally dangerous to humans due to their relatively small teeth and timid disposition. The so-called common thresher shark (A. vulpinus) is the largest species, reaching some 6 m in length, and occurs throughout the world in both continental waters and open ocean. The pelagic thresher shark (A. pelagicus) occurs in the tropical and subtropical waters of the Indian and Pacific oceans, usually far from shore but occasionally entering coastal habitats. The bigeye thresher shark (A. superciliosus) is found in temperate and tropical oceans worldwide. All are highly valued by commercial fisheries for their meat, fins, hide, and liver oil, with large numbers taken by longline and gillnets throughout their respective ranges. They are also favoured by recreational anglers for the exceptional fight they offer on hook-and-line.
Hammerhead sharks (Sphyrna) are so named for the unusual and highly distinctive structure of their heads, which are flattened and laterally extended into a ‘hammer’ shape, likely an evolution to enhance the animal’s vision. Although potentially dangerous they rarely attack humans. The great hammerhead shark (S. mokarran) is, as its name suggests, the largest species, with an average length of about 4.5 m, although some individuals may reach in excess of 6 m. It inhabits coastal tropical waters worldwide. The smooth hammerhead shark (S. zygaena) also has a global distribution in coastal waters, in both tropical and temperate waters. Both are extremely vulnerable to overfishing due to their low overall abundance and long generation time.
The zebra shark (Stegostoma tigrinum) is a type of nocturnal carpet shark found throughout the continental and insular shelves of the tropical Indo-Pacific, where it prefers coral reefs and sandy flats. The species is declining everywhere (except for Australia) due to overfishing for its meat, fins, and liver oil.
The tope shark (Galeorhinus galeus) is found worldwide in mainly temperate coastal waters, where it ranges to a depth of about 800 m. It has long been exploited for its liver oil, meat, and fins.
The kitefin shark (Dalatias licha), the largest of all luminous vertebrates, is found sporadically in coastal waters around the world, usually close to the sea floor at depths of 200–600 m. The species is fished commercially in some areas for its meat, skin, and liver oil, primarily by Portugal and Japan. One particular fishery targeting it existed off the Azores during the late nineteenth century, but ultimately collapsed due to overharvesting and falling liver oil prices. The rapid depletion of this stock has been cited as an example of the vulnerability of deep-sea sharks to human exploitation.
The winghead shark (Eusphyra blochii) is a small speciest hat occurs on or near continental shelf waters of the Indo-Pacific from the Arabian and Persian gulfs through South Asia to northern Australia and New Guinea. It is threatened by overfishing.
The hooktooth shark (Chaenogaleus macrostoma) is found in shallow coastal seas across the tropical Indo-Pacific, where it is considered vulnerable to fishing.
Plunket’s shark (Scymnodon plunketi) is a rare, deep-water species patchily distributed in the southern Indo-Pacific. Known records include the Melville Ridge south of Madagascar and the continental and insular slopes around Australia and New Zealand.
The broadfin shark (Lamiopsis temminckii) is a rare species with a sporadic distribution along the continental shelf of South and South East Asia. It has been severely depleted by overfishing.
The snaggletooth shark (Hemipristis elongata), also known as the fossil shark, has a wide distribution in the western and central Indo-Pacific, where it is nevertheless rare and vulnerable to fishing.
The little sleeper shark (Somniosus rostratus) is a rarely encountered deep-water species known from the north-eastern Atlantic and Mediterranean Sea, with additional records from the Caribbean and south-western Pacific (New Zealand).
The angular roughshark (Oxynotus centrina) is found in coastal waters of the eastern Atlantic, including the Mediterranean, from Scandinavia to South Africa. It is threatened mainly by bottom trawling.
The sicklefin weasel shark (Hemigaleus microstoma) is known patchily from the coastal waters of southern and South East Asia, and possibly the Red Sea and the Philippines as well, where it is threatened by fisheries activity.
The short-tail lanternshark (Etmopterus brachyurus) is a small deep-water species known only from a few disjunct localities in the western Pacific (i.e. Japan, the Philippines, and off eastern and western Australia).
The graceful catshark (Proscyllium habereri) is an uncommon bottom-dwelling species from the continental and insular shelves of the western Pacific, where it is threatened in many areas by overfishing and by-catch.
The spongehead catshark (Apristurus spongiceps) is a rare deep-sea species long known only from two specimens collected from the eastern and western Pacific. It was seen alive for the first time in 2002 off the north-western Hawaiian Islands from a submersible at a depth of about 1 km. The humpback catshark (A. gibbosus) is known from a few specimens collected within the north-western Pacific, where it may potentially be vulnerable to by-catch in deep-sea trawl fisheries.
Several species of angelshark (Squatina), so-named for their flattened bodies, inhabit shallow coastal seabed’s where they are seriously threatened by overfishing and trawling bycatch. The smoothback angelshark (S. oculata) and the sawback angelshark (S. aculeata) are both found patchily in coastal waters off the Mediterranean Sea and along the western coast of Africa. The ornate angelshark (S. tergocellatoides) is known only from a few areas along the coasts of China, Taiwan, Vietnam, and Borneo. The white-spotted angelshark (S. albipunctata) is confined to the eastern coast of Australia from northern Queensland to Victoria.
The sharptooth lemon shark (Negaprion acutidens) remains widespread in tropical waters from Africa to the Pacific Islands, where it is vulnerable to inshore fishing.
The tawny nurse shark (Nebrius ferrugineus) is found in shallow continental and insular shelves across the Indo-Pacific, often within the intertidal zone, where it is vulnerable to heavy fishing pressure.
Several species of deep-water gulper shark (Centrophorus) are seriously threatened by both targeted and incidental fishery activities. The dwarf gulper shark (C. atromarginatus), smallfined gulper shark (C. moluccensis), longfin gulper shark (C. longipinnis), and the longnose gulper shark (C. isodon) are each found widely but patchily within coastal waters of the tropical Indo-Pacific. The leafscale gulper shark (C. squamosus), granular gulper shark (C. granulosus), and Leslie’s gulper shark (C. lesliei) have a similarly widespread yet patchy distribution within the Atlantic and Indo-Pacific.
The whitetail dogfish (Scymnodalatias albicauda) has a patchy distribution in the southern oceans, where it has been recorded from the south-eastern Atlantic, southern Indian, and south-western Pacific oceans.
The spiny dogfish (Squalus acanthias) is a small, migratory species still found along temperate continental shelves worldwide with the exception of the northern Pacific, where it is replaced by a different species. It has suffered considerable declines due to overfishing compounded by a low reproductive capacity.
Linnaeus’ smoothhound (Mustelus mustelus) is a type of bottom-dwelling houndshark found on the continental and insular shelves of the eastern Atlantic Ocean from the British Isles to South Africa, as well as in the Mediterranean Sea and the Madeira and Canary Islands. While still abundant in some areas it is highly vulnerable to overfishing and by-catch in trawl and gill nets. The humpback smoothhound (M. whitneyi) and the narrownose smoothhound (M. schmitti) are both largely confined to the continental shelves of western South America, where they are also seriously threatened by overfishing.
Matallanas’ chimaera (Hydrolagus matallanasi) is known only from a small number of specimens collected in deep waters off south-eastern Brazil.
Three sawfish of the genus Pristis are seriously threatened by fishing activity, as their large, toothy rostrums are easily entangled in nets. The green sawfish (P. zijsron) is perhaps the largest species, capable of reaching a total length of over 7 m although rarely more than 6 m today. Historically widespread in coastal tropical and subtropical waters of the western and central Indo-Pacific from Africa to Taiwan and south to Australia, it has disappeared from most of its former range. The dwarf sawfish (P. clavata) was historically found throughout the coastal Indo-Pacific from India to New Guinea, but appears to have been extirpated everywhere except along the northern coast of Australia. The largetooth sawfish (P. pristis) occurs in tropical and subtropical coastal areas worldwide, occasionally entering freshwater rivers as well. The smalltooth sawfish (P. pectinata) was historically found in coastal waters from the south-eastern United States to Uruguay, including the Gulf of Mexico and the Caribbean Sea, and in the east from Senegal to Angola. Old reports from the Mediterranean were most likely vagrants. The species has been wholly or nearly extirpated from large areas of this former range due overfishing (trawl and inshore netting), and only survives now in small, fragmented populations. A small captive population exists, mainly in North America.
The knifetooth sawfish (Anoxypristis cuspidata) was historically found across the tropical and subtropical Indo-Pacific from the Persian Gulf to northern Australia and north to Japan and the Korean Peninsula. Its coastal distribution and toothed rostrum, which is easily entangled in nets, makes it highly susceptible to fishing pressure and the species has disappeared from many areas.
Several guitarfish of the genus Glaucostegus are seriously threatened by overfishing for their meat and fins. The sharpnose giant guitarfish (G. granulatus) is found patchily in the coastal waters of southern Asia from the Persian Gulf to Myanmar. The clubnose giant guitarfish (G. thouin) occurs in the coastal Indo-Pacific from India to Borneo. The shovelnose giant guitarfish (G. typus) is relatively widespread within the eastern Indian and western Pacific oceans from India and Taiwan to Australia. The widenose giant guitarfish (G. obtusus) is found in the coastal northern Indian Ocean from Pakistan to the Gulf of Thailand. The blackchin giant guitarfish (G. cemiculus) occurs in the coastal waters of the Mediterranean Sea and the eastern Atlantic from Spain to Angola.
Schlegel’s guitarfish (Rhinobatos schlegelii) is confined to a relatively small area of the north-western Pacific, where it occurs in the coastal waters of Japan, the Korean Peninsula, south-eastern China, and Taiwan. Linnaeus’ guitarfish (R. rhinobatos) is found in shallow coastal waters of the Mediterranean Sea and the Atlantic coast from the Bay of Biscay to Angola. Both are threatened by intense, unregulated fishing pressure.
The speckled guitarfish (Pseudobatos glaucostigmus) is found in shallow coastal waters from the Gulf of California to Ecuador, where it is threatened by gillnet fisheries and trawling by-catch.
Several enormous rays of the genus Mobula have been greatly depleted by both targeted and untargeted artisanal fisheries and are greatly prized for their gill plates, which are used in ‘traditional medicine’. The giant manta ray (M. birostris), as its name suggests, is the world’s largest ray species, reaching a disc size of up to 7 m across and a weight of around 3000 kg. The devil ray (M. mobular) is another very large species found patchily in coastal tropical and subtropical waters throughout the world. The reef manta ray (M. alfredi) is still widespread in coastal waters throughout the tropical and subtropical Indo-Pacific. The sicklefin devil ray (M. tarapacana) is found patchily worldwide in deep tropical, subtropical, and warm temperate waters, rarely appearing near coastal areas.
The longheaded eagle ray (Aetobatus flagellum) has a highly disjunct distribution across the Indo-Pacific, where it favours inshore areas. Populations are concentrated in the Red Sea, the western Bay of Bengal, southern Indonesia, southern China, and the southern parts of the Korean Peninsula and Japan. The ocellated eagle ray (A. ocellatus) occurs within an ill-defined area of the western Indo-Pacific. Both are highly vulnerable to fishing pressure.
The Peruvian eagle ray (Myliobatis peruvianus) is confined to the continental slope of south-western South America from central Peru to central Chile.
Three eagle rays of the genus Aetomylaeus are threatened by overfishing. The mottled eagle ray (A. maculatus) is found in the coastal waters of the eastern Indian and western Pacific oceans from India to Java and north to eastern China. The banded eagle ray (A. nichofii) and the ornate eagle ray (A. vespertilio) are similarly found in coastal waters over a wide area of the tropical and subtropical Indo-Pacific.
The shark ray (Rhina ancylostoma) remains widespread in coastal areas across the Indo-Pacific from South Africa to New Caledonia and north to Japan, but are everywhere subject to intense fishing pressure.
The flapnose ray (Rhinoptera javanica) is widespread along the continental and insular shelves of the Indo-Pacific from South Africa to South East Asia and north to Japan. It is highly vulnerable, however, to a wide variety of fishing techniques and likely threatened by pollution and habitat destruction as well.
The spiny butterfly ray (Gymnura altavela) is found patchily in shallow coastal waters along both sides of the Atlantic as well as in the Mediterranean and Black seas. The zonetail butterfly ray (G. zonura) occurs in coastal waters from India through Indonesia and the Philippines north to China. Both species are threatened by trawl fisheries.
The blotched fantail ray (Taeniurops meyeni) is a type of stingray found throughout the nearshore waters of the tropical Indo-Pacific, where it lives on the bottoms of lagoons, estuaries, and reefs. It is threatened by fisheries activities.
The porcupine whipray (Urogymnus asperrimus) is a widespread but uncommon bottom-dwelling species from the coastal waters of the Indo-Pacific. The species has also been introduced into the eastern Mediterranean Sea via the Suez Canal, while a population along the western coast of Africa most likely represents an as yet undescribed species. It is threatened by intensive and largely unmanaged net and trawl fisheries. The mangrove whipray (U. granulatus) is similarly found widely but patchily within the tropical Indo-Pacific, where it prefers shallow inshore habitats such as mangroves, estuaries, and sand flats.
The scaly whipray (Brevitrygon imbricata) is found disjunctly within the tropical Indo-Pacific from the Red Sea and Mauritius to Indonesia, where it typically lives in inshore coastal areas such as estuarine habitats. It is threatened by habitat destruction and fisheries by-catch.
The white-spotted whipray (Maculabatis gerrardi) and the round whipray (M. pastinacoides) are both widespread along the coastal waters of the Indo-Pacific, but are everywhere threatened by overfishing.
Three whiprays of the genus Pateobatis are threatened by overfishing. The pink whipray (Pateobatis fai) is found widely but patchily within the shallow coastal waters of the tropical Indo-Pacific. Jenkins’ whipray (P. jenkinsii) and Bleeker’s whipray (P. uarnacoides) are both found patchily in the coastal waters of the Indian and western Pacific oceans.
Three whiprays of the genus Himantura are threatened by intense fishing pressure in many areas, particularly South East Asia. The honeycomb whipray (H. undulata) occurs in coastal waters of the Indo-Pacific from eastern India to Indonesia. The leopard whipray (H. leoparda) is known from the coastal waters of South East Asia from the Japanese Archipelago south to northern Australia. The reticulated whipray (H. uarnak) is a large species that inhabits coastal and brackish waters across the Indo-Pacific from South Africa to Australia and north to Taiwan. Small numbers have also managed to enter the Mediterranean Sea through the Suez Canal.
The smalleye stingray (Megatrygon microps) has a patchy distribution in the tropical Indo-Pacific that includes coastal areas of Mozambique, South Asia, the Gulf of Thailand, Indonesia, and northern Australia. It is frequently taken as by-catch.
The shortlip electric ray (Narcine brevilabiata) is found patchily along the shallow continental shelves of China, and South East Asia, where it is taken in large numbers as by-catch by shrimp trawlers.
The finless sleeper ray (Temera hardwickii) is a type of electric ray and possibly the world’s smallest cartilaginous fish. It is found along the continental shelf of South East Asia from the eastern Andaman Sea to Vietnam and possibly Borneo, where it is threatened by intensive bottom trawling.
The broadnose wedgefish (Rhynchobatus springeri) is known from the shallow coastal waters of the Gulf of Thailand, the Malay Peninsula, Sumatra, Borneo, and Java. The smoothnose wedgefish (R. laevis) and the bottlenose wedgefish (R. australiae) are both widespread in the shallow coastal waters of the Indian and western Pacific oceans. All are threatened by intense fishing pressure.
The giant skate (Dipturus gigas) and the acutenose skate (D. tengu) are confined to the coastal waters of the Korean Peninsula, southern Japan, Taiwan, and the northern Philippines, where they are threatened by fisheries by-catch.
Eaton’s skate (Bathyraja eatonii) has been reported sporadically in deeper coastal waters throughout the Southern Ocean, although it appears fairly certain that more than one species is involved. If so, this particular species is likely restricted to the waters of the Antarctic Atlantic (South Orkney, South Shetland, the Antarctic Peninsula, and the north-eastern Weddell Sea).
The bottlenose skate (Rostroraja alba) inhabits coastal waters of the eastern Atlantic from the southern British Isles south to South Africa, extending into the Mediterranean Sea and the south-western Indian Ocean. Its large size makes it vulnerable to fishing pressure and it has been heavily depleted and even extirpated in many parts of its former range.
The ocean sunfish (Mola mola) is one of the heaviest known bony fishes. While found in tropical and temperate coastal waters worldwide, in some areas (particularly Japan, the Korean Peninsula, and Taiwan) they are considered a delicacy and heavily fished, and often inadvertently caught in gillnets as well.
The blue marlin (Makaira nigricans) occurs throughout the warmer oceans of the world, but is everywhere threatened by overfishing and by-catch.
The white marlin (Kajikia albida) is found in the warmer waters of the Atlantic Ocean and Mediterranean Sea, where it is threatened by overfishing and by-catch.
The Atlantic tarpon (Megalops atlanticus) inhabits coastal waters, estuaries, lagoons, and even rivers in the Atlantic Ocean, where it favours tropical and subtropical areas, although it has been reported as far north as Nova Scotia and the coast of south-western France, and as far south as Argentina. A much sought after game fish in spite of the fact that its flesh is considered undesirable and bony, it has been much depleted.
Three species of tuna (Thunnus) are threatened by commercial overfishing. The Pacific bluefin tuna (T. orientalis) is found primarily in the North Pacific but occurs as well in the eastern Indian Ocean and also ventures into the tropical waters of the southern Pacific. Spawning has only been reported within the western North Pacific. The southern bluefin tuna (T. maccoyii) occurs in the southern parts of the Atlantic, Indian, and Pacific oceans, from where it moves up into tropical waters of the eastern Indian Ocean to spawn. The bigeye tuna (T. obesus) is found worldwide in both tropical and temperate waters with the exception of the Mediterranean Sea.
The bluefish (Pomatomus saltatrix) is a migratory pelagic fish found in about 8–10 isolated subpopulations worldwide, except for the eastern Pacific Ocean. It prefers temperate and subtropical coastal waters, and is highly vulnerable to unregulated fishing in some areas.
The haddock (Melanogrammus aeglefinus) has long been an important food fish and is harvested on an enormous scale (i.e. around 200,000–350,000 tonnes per year). Discrete populations are found on either side of the North Atlantic but are more abundant on the European side, where the species occurs from the Bay of Biscay north to the Arctic Ocean. The largest stocks are in the North Sea, off Iceland and the Faroe Islands and the coast of Norway. Off North America it is found from western Greenland south to Cape Hatteras (North Carolina), although the main commercially fished stock lies between Cape Cod and the Grand Banks. While overexploited in the past it now appears to be harvested sustainably, although there are concerns regarding the impact of bottom trawls on the marine environment.
The Atlantic cod (Gadus morhua) is a large, bottomdwelling shoaling fish that may reach upwards of 1.5 m in length and a weight of almost 50 kg, although most individuals today rarely attain half that size. An inhabitant of continental and insular shelves, in the western Atlantic it is found north of Cape Hatteras and around both coasts of Greenland and in the Labrador Sea, while in the east it occurs from the Bay of Biscay north to the Arctic Ocean, including the Baltic Sea, North Sea, Barents Sea, and areas around Iceland. One of the world’s most heavily fished species, it has been harvested for thousands of years by northern Europeans who eventually followed it across the Atlantic to North America, in particular the Grand Banks south-east of Newfoundland. By the 1990s several stocks completely collapsed under the pressure and a ban was finally put in place, although the former have yet to recover fully. Many other cod stocks remain at risk.
The Atlantic halibut (Hippoglossus hippoglossus) is the world’s largest flatfish and among the largest of all bony fish, reaching lengths of up to 4.7 m and a weight of 320 kg. It generally lives on the ocean floor in both the eastern and western Atlantic and into parts the Arctic Ocean. Formerly a very important commercial species, due to its slow population growth it has been unable to recover from previous overharvesting and the fishery has largely collapsed.
The Atlantic horse mackerel (Trachurus trachurus) is found in the northern and eastern Atlantic from Norway to the southern tip of Africa, including the Mediterranean, Marmara, and Black seas. An important species in commercial fisheries, it forms large, migratory schools that are taken by means of trawls, longlines, and purse seins. While still common in European waters the species has been largely eliminated in other areas, particularly off West Africa.
The Pacific menhaden (Ethmidium maculatum) is a type of small pelagic fish confined to the continental shelf of Peru and northern Chile, where it is subject to intense fishing pressure.
The dusky grouper (Epinephelus marginatus) is a large, oval-bodied fish found very disjunctly along the continental and insular shelves of western Europe, the Mediterranean, eastern South America, western and southern Africa, and Madagascar. A solitary inhabitant of rocky reefs and sea grass beds, it is a popular food fish much sought after by commercial fishermen as well as by spear-fishers and anglers. Its slow rate of reproduction and growth rate make it vulnerable to overexploitation.
The humpback grouper (Cromileptes altivelis) is a naturally rare if widely distributed species found along the continental and insular shelves from southern India to Japan and northern Australia. It is everywhere threatened by overfishing.
The squaretail coral grouper (Plectropomus areolatus) is widely but patchily distributed across the tropical Indo-Pacific from the Red Sea as far as Samoa, and from the Ryukyu Islands south to northern Australia. It is everywhere threatened by overfishing.
The scalyfin basslet (Liopropoma longilepis) is a type of small grouper known sporadically from the Gulf of California to the Gulf of Panama.
The golden threadfin bream (Nemipterus virgatus) is found disjunctly in the shallow continental and insular waters of the western Pacific from southern Japan to northern Australia. One of the most important commercial fisheries species in the East China and South China seas, it has undergone significant declines in recent decades.
The Vacuocua croaker (Corvula macrops) is a notably uncommon species found in the continental and insular waters of the eastern Pacific from the Gulf of California to Ecuador, including the Galápagos Islands.
The green humphead parrotfish (Bolbometopon muricatum) is a notably large species that was historically common in coral reefs throughout the Indo-Pacific from the Red Sea to Samoa and from the Yaeyama Islands to the Great Barrier Reef. Highly vulnerable to overfishing, it is now considered rare and has disappeared from many areas.
The spot-fin parrotfish (Scarus maculipinna) is known from reefs off southern Thailand, the Mentawai Islands, and western Java.
The grey triggerfish (Balistes capriscus) is found throughout much of the Atlantic in deeper coastal waters from Nova Scotia to Argentina and west to West Africa, the Mediterranean and the British Isles. It has been declared throughout its range due to overfishing.
The West African goatfish (Pseudupeneus prayensis) is a perch-like species found in the eastern Atlantic between southern Morocco and Angola, including the waters of the Cape Verde Islands and, rarely, the western Mediterranean. An important food fish along the West African coast, it is heavily harvested and has suffered significant declines.
The longfin Pacific anchovy (Anchoa analis) is a small, silvery fish confined to the coastal waters of north-western Mexico. It is threatened by loss of habitat.
The Madeiran sardinella (Sardinella maderensis) is found in the eastern Atlantic and south-eastern Mediterranean along continental and insular shelves, where it is heavily exploited in some areas by commercial fisheries.
The whitetail damselfish (Stegastes leucorus) is largely confined to reefs around the Revillagigedos Islands, but it also occasionally recorded from the Gulf of California and along the western coast of Mexico. It is potentially threatened by strong El Niño events, which result in shallow waters that are too warm and nutrient-poor for extended periods.
The humpnose unicornfish (Naso tuberosus) is known only from a few specimens collected from coral reefs across the Indian Ocean (Mauritius, the Seychelles, Mozambique, Cocos Island, and south-western Australia). The reticulated unicornfish (N. reticulatus) is known only from three specimens collected off Taiwan, the Philippines, and south-western Sumatra.
Cantor’s pufferfish (Arothron carduus) is known only from two specimens collected from disjunct coral reef localities off the Malay Peninsula and in the Ryukyu Islands. A third specimen was purchased dried from a fish market in Japan, and is thought to have originated in the Philippines.
The diamond-tail fairy-wrasse (Cirrhilabrus rhomboidalis) is largely confined to the Caroline and Marshall Islands, with vagrants occasionally recorded from Palau and Saipan in the Mariana Islands.
The humphead wrasse (Cheilinus undulatus) is a large, naturally rare species still found across the Indo-Pacific. It is threatened by overfishing and the destruction of its coral reef habitat.
The five-striped hogfish (Bodianus paraleucosticticus) is known only from a few specimens collected off Rarotonga and Papua New Guinea, and from a photo taken off New Caledonia. The barred hogfish (B. scrofa) is confined to rocky reefs around the eastern Atlantic archipelagos of the Azores, Madeira, Selvagens, Canary, and Cape Verde islands, where it is threatened by overfishing. The red-sashed hogfish (B. rubrisos) is known only from a few specimens collected from off southern Japan, Taiwan, Bali, and northern Australia.
The long-tailed filefish (Cantherhines longicaudus) is known only from a few specimens collected across a wide area of the tropical Indo-Pacific. Known localities include New Caledonia, Tahiti, the Cook Islands, the Tuamotu Archipelago, and the Austral Islands.
The harlequin filefish (Oxymonacanthus longirostris) is widespread along the continental and insular shelves of the tropical Indo-Pacific from eastern Africa to Tonga and can be locally abundant in areas. However, the species is dependent upon shallow Acropora (stony) coral reefs, and is therefore highly susceptible to habitat destruction. It is also heavily collected for the international aquarium trade despite the fact that it rarely survives long in captivity.
The lowfin dartfish (Ptereleotris brachyptera) is known only from a handful of specimens collected from three widely separated fringing reef localities (coastal Borneo, Palau, and the Marshall Islands).
The Fijian leatherjacket (Thamnaconus fijiensis) is a rare type of filefish known only from three specimens collected from Fiji, New Caledonia, and the Kii Peninsula of Honshu, Japan.
The darkblotch goby (Parrella ginsburgi) is known only from a few specimens collected along the western coast of North and Central America.
The frailscale goby (Bollmannia macropoma) and the apostrophe goby (B. marginalis) are each known only from a few disjunct deep-water collections between the Gulf of California and Ecuador.
The rail goby (Chriolepis cuneata) is known only from a few specimens collected along the western coast of North and Central America.
Several cryptic species of worm-goby (Microdesmus) are threatened by coastal development and loss of mangrove habitat. The spotside worm-goby (M. suttkusi), spotback wormgoby (M. dorsipunctatus), banded worm-goby (Microdesmus dipus), olivaceous worm-goby (Microdesmus affinis), and the rearfin worm-goby (M. retropinnis) are all known only from a few specimens collected from continental and insular areas of the eastern Pacific between the Gulf of California and northwestern South America.
Hoese’s blenny (Starksia hoesei) is known only from a few specimens collected from the Gulf of California and the western coast of Mexico (Guerrero) in 1975.
The Antarctic triplefin blenny (Helcogrammoides antarcticus) is a subtidal species known only from a few specimens collected from Paradise Bay, on the Antarctic Peninsula.
The Hikkaduw combtooth blenny (Omobranchus hikkaduwensis) is known only from two widely separated shallowwater localities (Sri Lanka and Bali). Smith’s combtooth blenny (O. smithi) is known only from three estuaries along the South Asian coast between western India to southern Vietnam.
The shortjaw bonefish (Albula glossodonta) is found throughout the tropical Indo-Pacific but is everywhere subject to intense fishing pressure.
Dorothea’s wriggler (Allomicrodesmus dorotheae) is a reefdwelling fish known only from two specimens, one collected from the Great Barrier Reef and the other from the Marshall Islands.
Nielsen’s slickhead (Bathylaco nielseni) is a type of deepsea smelt known only from two localities in the eastern central Atlantic and western Indian Ocean.
Several species of seahorse (Hippocampus) have undergone significant declines due to coastal development, pollution, trawling by-catch, and collection for use in ‘traditional medicine’. The giant seahorse (H. ingens) is found from Long Beach, California and along the western coast of the Americas as far south as Peru, with additional populations around Malpelo and the Cocos Islands and the Galápagos Islands. The spotted seahorse (H. kuda) remains widespread from the Persian Gulf and the eastern coast of Africa to South East Asia, Australia, Japan, and a few Pacific islands including Hawaii. Mohnike’s seahorse (H. mohnikei) was long known only from the waters around Japan, but has since been recorded as far away as coastal south-eastern India and South East Asia. The hedgehog seahorse (H. spinosissimus) is found from India to Taiwan and south to northern Australia. The tiger-tail seahorse (H. comes) occurs within the continental and insular areas of South East Asia, Indonesia, and the Philippines. The three-spot seahorse (H. trimaculatus) is widespread within the shallow continental and insular waters of the eastern Indian and Western Pacific oceans. Kellogg’s seahorse (H. kelloggi) and the spiny seahorse (H. histrix) are both widespread within the Indo-Pacific from Africa to Japan and Polynesia.
Southwell’s pipefish (Siokunichthys southwelli) is known only from four specimens collected at two widely separated localities (Marichchukkaddi Bay in Sri Lanka and Mindoro, Philippines).
Wass’ pipefish (Festucalex wassi) is only known from six specimens collected off New Guinea, New Caledonia, Fiji, and Samoa.
Krefft’s snailfish (Paraliparis kreffti) is known only from the Scotia Sea in the South Atlantic and the Weddell Sea off Antarctica.
The Japanese eel or unagi (Anguilla japonica) is found in the north-western Pacific primarily in the region of China, Japan, and the Korean Peninsula. Like other members of its genus, it is migratory and catadromous, meaning that it spawns in the sea but lives parts of its life in freshwater (i.e. rivers, lakes, and estuaries). An important food fish raised in aquaculture ponds in many countries, it is heavily exploited in the wild state and has consequently suffered significant declines. The European eel (A. anguilla) is thought to spawn within the Sargasso Sea in the west-central Atlantic, but spends most of its life in the fresh inland waters of Europe and northern Africa. The American eel (A. rostrata) similarly lives most of its life in freshwater areas and was historically widespread in southern Greenland, eastern and central North America, Central America and the Caribbean, and northern South America. It too spawns in the Sargasso Sea, an ocean gyre characterized by its brown Sargassum seaweed and often calm blue water. All are threatened by overfishing, freshwater habitat destruction and degradation, barriers to migration due to hydroelectric dams, invasive species, parasitism, and pollution.
The many-spotted moray eel (Uropterygius polystictus) is known only from a few records from the eastern Pacific (Gulf of California and the Galápagos Islands).
The wide-mouth moray eel (Gymnothorax eurygnathos) is known only from two specimens collected from the Gulf of California and off El Salvador.
Kazuko’s false moray eel (Chlopsis kazuko) is known only from five specimens collected from the Gulf of California, Malpelo Island, and off the coast of Costa Rica. It was last recorded in 1988.
The blackedge conger eel (Bathycongrus retrotinctus) is known for certain only from a few specimens collected from deep waters in the Philippines, although it may also occur in the Sea of Japan.
Eriksson’s blind cusk-eel (Nybelinella erikssoni) is known only from a few specimens collected from great depths in the Atlantic and western Indian oceans.
Anthropogenic effects on the flora and fauna
We have seen through this website just how humans have impacted the oceans through pollution, whaling, and overfishing. In terms of more direct effects upon species as a whole, it is gratifying to know that few have been lost. In recent historical time (i.e. since ad 1500), the Oceanic Realm as a whole has lost at least 3 species of vertebrates. Among the extinct forms 1 species is a mammal and 2 species are marine fishes. Another 7 species of marine fishes are possibly extinct. In addition, there are 1388 species/16 subspecies 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, 29 species/11 subspecies are mammals, 23 species/1 subspecies are reptiles, and 1336 species/16 subspecies are marine fishes.