Japanese Topeshark

• Maximum lengthAbout 1.2 m (4 ft); most adults 0.8–1.1 m
• WeightNot recorded; probably under 10 kg (22 lb)
• LifespanUnknown; no validated age study
• Depth rangeContinental shelf, surface to about 100 m (330 ft)
• DietSmall bony fish, crustaceans, squid
• IUCN statusEndangered (assessed 2019)

How to identify a Japanese topeshark

Picture a small, elegant houndshark with the proportions of a miniature tope, and you have most of it. The body is slender and rounded, the snout long and narrowly pointed when seen from above, and the nostrils carry broad triangular flaps of skin that do not quite reach the mouth. The eyes are horizontally oval, set high on the head, and fitted with a proper nictitating lower eyelid, a feature of houndsharks that separates them at a glance from the catsharks with which small Asian sharks are often lumped. Behind each eye is a small spiracle.

The fins give the genus away. In adults every fin is noticeably falcate, curved back like a sickle, and the second dorsal fin is large, roughly three-fifths to three-quarters the height of the first. The first dorsal begins above the rear inner corner of the pectoral fins. Tope and the blacktip tope (Hypogaleus hyugaensis), which share these waters, have a much smaller second dorsal fin and a big terminal lobe on the tail.

Colour is grey to greyish bronze on the back, often with a faint metallic sheen in a freshly landed fish, and clean white below. Young sharks have conspicuous white tips and trailing edges on the dorsal, pectoral and caudal fins; in adults those white margins fade but usually remain traceable. The teeth are small, compressed and blade-like, each with an oblique main cusp flanked by one or more small cusplets on the outer side, and they look the same in both jaws. The mouth is broadly arched, with long furrows at its corners. Nothing about the animal is spotted, banded or blotched, which rules out the banded houndshark and the starry smooth-hound immediately.

How big does a Japanese topeshark get?

By any standard this is a small shark. The largest females reliably measured are about 1.2 m (4 ft) long; the largest males are around 1.1 m. Most adults seen in Taiwanese and Japanese landings fall between 0.8 and 1.1 m, and a shark of a metre already counts as a good-sized specimen. Females run slightly larger than males, which is the usual houndshark pattern.

Newborns are roughly 20 cm (8 in), miniature but complete, with the white fin edges at their brightest. Maturity comes at a little over half the maximum length: males at about 80 to 90 cm and females at about 90 to 100 cm. Published weights are lacking; a 1.2 m houndshark of this build would weigh a few kilograms at most, and no reliable maximum weight exists. The bar below sets the 1.2 m maximum against a 1.8 m diver, which shows how modest an animal this is.

Where Japanese topesharks live

The Japanese topeshark is confined to the north-western Pacific, and within it to the continental shelf. Its range runs from the Pacific and Sea of Japan coasts of southern Honshu, Shikoku and Kyushu in Japan, across the south coast of South Korea and the Jeju shelf, through the Yellow Sea and East China Sea off China, to Taiwan, which sits at the southern edge. The published limits are roughly 40°N to 21°N. Reports from farther south, in Vietnamese and Philippine waters, are unconfirmed and may involve other Hemitriakis species.

It is a bottom-living shark of temperate to subtropical shelf water, found from close inshore down to about 100 m (330 ft), over sand and mud rather than reef. The great majority of specimens come from bottom trawls working the shelf in 30 to 100 m, which suggests that is where the population is densest, though trawl data always favour the depths the nets fish. It does not enter rivers or estuaries.

Japanese fishermen report the species inshore mainly in the warmer months, which hints at a seasonal movement between shallow summer grounds and deeper winter water, but no tagging has been done and the pattern remains unmeasured. The map below shows the range; for the region's other species see where sharks live.

What Japanese topesharks eat

The teeth tell you this is a grabber of small, soft prey rather than a cutter, and the few stomach studies, mostly from Taiwan, confirm it. The diet consists of small schooling bony fish such as anchovies, sardines and lizardfish, together with shrimps, crabs and mantis shrimps from the seabed and small squid and cuttlefish. No larger prey has been recorded, and a shark with a mouth this size would struggle to take any.

Hunting probably happens close to the bottom and at least partly at night, as it does in other houndsharks, with the shark quartering the sediment for buried crustaceans and picking off fish from the edges of shoals. The long snout is packed with electroreceptors, the ampullae of Lorenzini, which let it find a shrimp under a centimetre of sand by the electric field of its heartbeat, and a well-developed sense of smell guides it to injured or dead fish. That smell works across tens or hundreds of metres, not the mythical miles (see how far sharks can smell blood). Nothing suggests cooperative hunting; the schools sometimes trawled together are more likely to reflect shared habitat than shared tactics.

Behaviour and senses

Almost everything known about the Japanese topeshark comes from dead animals on a market slab or a research trawl, so its behaviour is inferred rather than observed. It is an active swimmer that must keep moving to breathe, like its relatives. Trawlers regularly take several sharks in one haul, and the sexes are often uneven in those hauls, which is the usual sign of a species that segregates by sex for part of the year.

The senses are the standard set for a shelf-dwelling shark and tuned to a dim, silty environment. The large oval eyes, with a reflective layer behind the retina, cope with the low light of 80 m; the lateral line detects the pressure wave of a fish turning nearby; the electroreceptors handle the last few centimetres of an attack. The nictitating eyelid closes across the eye when the shark bites, a protection the great white lacks (see shark anatomy).

Migration is unstudied. The inshore appearances in Japanese summers and the winter dominance of deeper trawl catches point to a modest seasonal shift up and down the shelf, and pupping in shallow water in spring would fit that picture, but no tagged shark has ever been tracked.

Reproduction and lifespan

Older descriptions, including the earlier version of this page, called the Japanese topeshark ovoviviparous. That is wrong for the genus. Hemitriakis is viviparous with a yolk-sac placenta: the embryo lives on its yolk for the first months, and when the yolk runs out the emptied sac attaches to the wall of the uterus and passes nutrients from the mother's blood until birth. It is the same arrangement found in the tope and most requiem sharks, and one of the four ways sharks reproduce.

Litters are large for such a small shark: 8 to 22 pups, each about 20 cm at birth. The length of pregnancy has not been established with confidence; comparable houndsharks carry their young for around ten to twelve months, and the seasonal appearance of pregnant females inshore in Japanese and Taiwanese waters suggests a spring or early-summer birth season. Nursery grounds, if the species uses them, have not been mapped. Whether females breed every year or rest between litters is also unknown.

Maturity is reached at about 80 to 90 cm in males and 90 to 100 cm in females. No validated age study has been published, so the lifespan given on some websites is guesswork; houndsharks of this size typically live ten to twenty years, and that is the honest range for this one. What matters for conservation is the combination of a large litter with a probable late maturity, which makes the population look more resilient than it is. For how ages are measured in sharks, see how long sharks live.

Is the Japanese topeshark dangerous to people?

No. A shark that tops out at 1.2 m, with a mouth built for anchovies and shrimps and teeth a few millimetres high, cannot inflict a serious wound even if it wanted to, and there is no evidence it ever wants to. It lives on the seabed of the shelf, away from surf beaches, and its only regular contact with people is on the deck of a trawler. The SharkSider database holds no incident attributed to the species, and the only "tope" bite it records, an angler nipped by a hooked shark in England, involves the Atlantic tope, a different genus.

The danger runs entirely the other way. The Japanese topeshark is eaten across its range, sold fresh and dried in Taiwan, Japan and China, and its fins enter the trade in small sizes. If you handle one on a boat, mind the rough skin and the abrasive teeth as you would with any small shark, and put it back quickly; the population needs every one.

The SharkSider database has no incident attributed to this species. The database draws on the International Shark Attack File, the Global Shark Attack File and verified local reports, and is updated weekly.

Conservation status

The IUCN Red List assessed the Japanese topeshark as Endangered in 2019, a steep upgrade from the Data Deficient listing it carried for years. The reasoning is straightforward. Its entire range lies within some of the most intensively fished shelf waters on earth: the bottom-trawl, gillnet and longline fleets of China, Taiwan, Japan and Korea work the East China Sea and Yellow Sea continuously, and a small demersal shark with no refuge in deep water is caught in all of them. Fishery-independent trawl surveys and market monitoring, particularly at Taiwanese landing sites, show declines that the assessors estimated at more than half over three generations.

The species is not listed on CITES or the Convention on Migratory Species, and no range state gives it specific protection; it is landed and sold without limit. The meat goes to local markets, the fins to the wider trade that feeds shark fin soup, and the liver to oil. Because landings are usually recorded simply as "shark" or "houndshark", declines in this one species are easy to miss.

Habitat pressure adds to the fishing. The shallow shelf and coastal bays where pups would be born are heavily modified by reclamation, aquaculture and pollution along the Chinese and Taiwanese coasts. There is no recovery plan anywhere. The Japanese topeshark is a good example of why sharks are endangered even when no one targets them: a small, unglamorous animal disappearing in the bycatch of fisheries that barely notice it.

Similar species and close relatives

The genus Hemitriakis contains six recognised species, all in the western Pacific, and telling them apart is a job for specialists working from fin positions, tooth details and vertebral counts. The whitefin topeshark (H. leucoperiptera) of the Philippines is the best known, with bolder white fin margins; H. complicofasciata from the Ryukyu Islands and Taiwan has a dark banded pattern in the young; H. abdita, H. falcata and H. indroyonoi live off Australia and Indonesia. Where ranges overlap, in Taiwanese waters especially, mixed catches are almost certainly being sold under one name.

Among other houndsharks in the same seas, the blacktip tope has a black-tipped first dorsal fin and a small second dorsal; the tope is larger, greyer and has that big lower lobe on the tail; the banded houndshark is thickset and marked with dark saddles and spots; and the starry smooth-hound and its relatives have flat, pavement-like crushing teeth instead of blades. A plain silvery houndshark with sickle-shaped fins, a big second dorsal and blade teeth, landed anywhere between Kyushu and Kaohsiung, is a Japanese topeshark.

• Whitefin Topesharkspecies profile
• Blacktip Topespecies profile
• Tope Sharkspecies profile
• Banded Houndsharkspecies profile
• Starry Smooth-Hound Sharkspecies profile
• Bigeye Houndsharkspecies profile

Written and reviewed by

SharkSider Editorial Team

A small team focused on researching sharks and making marine biology easy to understand. Every page is reviewed against current species records and the SharkSider attack database, and updated when new incidents or research appear.

Published October 25, 2022 · Last updated September 22, 2026 · No incident attributed to this species in the SharkSider attack database, which is updated weekly.