Sandbar Shark

Maximum longevity: 32 years Observations: These animals live at least 30 years (Das 1994), but it is possible that some may live over 50 years (http://www.fishbase.org/).

According to Stillwell et al. (1993), sharks are an integral part of the flow of energy in marine ecosystems. Sandbar sharks are considered predators rather than prey, but juveniles may be preyed upon by other sharks. Sandbar sharks are a common host for a number of parasitic copepods, including those in the families Pandaridae, Caligidae, Euphoridae, and Eudactylinidae. Other parasites are isopods in the Gnathiidae family and annelids in the Hirudinidae family, which are both typically attached to the gill filaments. Copepods are often found on the body or fins of the sharks.

Commensal/Parasitic Species:

• Pandaridae
• Hirudinidae
• Caligidae
• Gnathiidae
• Euphoridae
• Eudactylinidae
• Echeneidae

Like many other types of sharks, sandbar sharks have few predators. Pups and juveniles, however, often become prey of larger members of the Chondrichthyes class. The only other predators to sandbar sharks are humans (Homo sapiens). They are very popular in shark fisheries and are the most common shark fished on the east coast of the United States. According to the IUCN Red List “sandbar sharks were found to represent at least 2 to 3% of the fins auctioned in Hong Kong, the world’s largest shark fin trading center.” Due to the high value of their fins they are overfished and therefore have experienced population declines.

Known Predators:

• humans (Homo sapiens)
• other sharks (Chondrichthyes)

Anti-predator Adaptations: cryptic

Sandbar sharks are generally a grey-brown color or “bronzy,” as Compagno, et al. (2005) described. They have white undersides and dusky posterior edges to their fins. They also have an “inconspicuous” white band on their flank. Compagno et al. (2005) described them as having a “moderately long rounded snout” and “high triangular saw-edged upper teeth.” Their first dorsal fins are especially large compared to other sharks. As newborns, these sharks are about 56 to 75 cm total length (TL). At maturity they reach 140 to 180 cm total length and as adults they reach 240 to 300 cm total length. These sizes may vary depending on location.

Range mass: 45 to 90 kg.

Range length: 240 to 300 cm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: sexes alike

Sandbar sharks are considered long-lived. However, few sources reveal information on the lifespan and longevity of sandbar sharks. In one study, Joung et al. (2004) found the oldest male to be 19.8 years old and the oldest female to be 20.8 years old. While, Sminkey et al. (1996) mention that sandbar sharks can live to be over 30 years old. According to Joung et al. (2004), “lack of accurate age information on sharks has been a major stumbling block to fisheries research.” Sandbar sharks can be found in captivity in aquariums, but captive lifespan is unknown.

Average lifespan
Status: wild: 20 years.

Sandbar sharks tend to be coastal, typically found on muddy or sandy flats in bays, harbors, estuaries and river mouths. They may also be found offshore, on banks near islands or flat reefs. Sandbar sharks may live in depths ranging from 1 m (inter tidal waters) to 280 m in water with salinities of ~20 parts per thousand (ppt). Juveniles inhabit coastal nursery areas of temperate waters to eat and avoid predation. Adults are migratory and prefer tropical waters.

Range depth: 1 to 280 m.

Average depth: 20-55 m.

Habitat Regions: temperate ; tropical ; saltwater or marine

Aquatic Biomes: pelagic ; coastal

Other Habitat Features: estuarine

Sandbar sharks are found worldwide in tropical and warm temperate waters. These sharks can be found in the western Atlantic, the eastern Atlantic, the western Pacific, the western Indian, and the eastern Indian oceans. They may also be found in the Caribbean, Gulf of Mexico, and the Mediterranean Sea. Important areas for juveniles in United States include Cape Cod, Massachusetts; Cape Canaveral, Florida; Bulls Bay, South Carolina; Delaware Bay, New Jersey; the Chesapeake Bay, and the Eastern Shore of Virginia.

Biogeographic Regions: indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native ); mediterranean sea (Native )

Other Geographic Terms: cosmopolitan

Sandbar sharks mainly feed opportunistically on small bottom fish, mollusks, and crustaceans. Research suggests that their diet is related to their size. Juveniles and smaller sharks mainly feed on crustaceans, such as blue crabs (Callinectes sapidus) and mantis shrimp (Lysiosquilla scabricauda). Larger sharks feed may feed on crustaceans as well, but will also consume elasmobranch prey including small sharks, skates, and rays. According to the IUCN Red List, a sandbar shark’s diet may include “sardines, shad, menhaden, anchovies, sea catfishes, moray and snake eels, pipefish, barracuda, mullets, goatfishes, hairtails, spanish mackeral, bonito, mackeral (Scomberomorus brasiliensis), jacks, groupers, croakers, grunts, porgies, flounders and soles, sea robins, toadfish, cusk eels, porcupine fish, sharpnose sharks (Rhizoprionodon terraenovae), spiny dogfish (Squalus acanthias), bonnethead sharks (Sphyrna tiburo), guitarfish, skates, stingrays, squid, cuttlefish, octopi, bivalves and conchs, amphipods, shrimp and crabs.” Sandbar sharks are known to feed more actively at night.

Animal Foods: fish; mollusks; aquatic crustaceans

Primary Diet: carnivore (Piscivore , Eats non-insect arthropods, Molluscivore )

Sandbar sharks are a large part of the commercial shark fishery in the eastern United States as well as numerous other parts of the world. They are caught for their hide, meat, fins, and liver. Sandbar sharks, above other types are sharks, are more sought after because of their size and high fin-to-carcass ratio. In recent decades, demand for them has increased tremendously. Sandbar sharks make up about 60% of the catch in fisheries along the United States Atlantic coast. Recreational fishermen also catch them as a game fish.

Positive Impacts: food ; body parts are source of valuable material

Sandbar sharks are not considered a threat to humans, although their size could make them dangerous. They may become aggressive when provoked.

Negative Impacts: injures humans (bites or stings)

Sandbar sharks have internal fertilization and are viviparous, meaning they give birth to live young. The embryos remain in the uterus for 9 to 12 months until they are fully developed, during which time they receive nutrients from the placenta. When the pups are born they have the same physical features as adults, but they are smaller. It takes about 8 years for sandbar sharks to mature.

Slow growth rate and late maturation make sandbar sharks extremely vulnerable to overfishing. This is a concern due to their wide popularity in coastal fisheries worldwide. In 1996, the International Union for Conservation of Nature and Natural Resources (IUCN) Red List assessed them as vulnerable, but were re-assessed and changed to Lower risk/near threatened in 2000. Then, in 2007 sandbar sharks were listed again as vulnerable. In 1993, a management plan was created for the U.S. that involves catch and size restrictions for commercial fisheries. The plan seems to have helped slow the decline in the North Atlantic population. Western Australia has also implemented a management plan with similar guidelines. Management plans for other parts of the world have been slow coming due to insufficient data on age and growth of the sharks.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: vulnerable

There is little information on communication between sandbar sharks. Although, during mating, male sandbar sharks will bite the females until they flip upside down. Sharks have excellent sensory acuity that aid in finding prey and avoiding predators. They have an exquisite sense of smell that is useful for locating food. Sharks also have an electrosensory system, which is an ampullary electroreceptor system. With this system, sharks are capable of detecting “weak extrinsic electric stimuli as low as 5 nV/cm,” according to Carrier et al. (2004)

Communication Channels: tactile

Perception Channels: visual ; acoustic ; chemical ; electric ; magnetic

Male and female sandbar sharks only interact during mating; otherwise the sexes swim in separate schools. To initiate mating, male sandbar sharks follow and bite the dorsal fins of females until they flip over. Once flipped over, the male inserts one clasper into the cloaca. Sandbar sharks are considered polygynandrous, meaning females will reproduce with multiple males.

Mating System: polygynandrous (promiscuous)

Sandbar sharks mate in the warm months of the year and females only give birth every 2 to 3 years. The gestation period for sandbar sharks ranges between 9 and 12 months and they may give birth to litters ranging from 1 to 14 pups. The gestation period, litter size, and time of the year when pups are born vary depending on geographic location. Males reach sexual maturity at 160 to 165 cm total length or when claspers are fully developed and have reached the proper hardness. Female sharks reach sexual maturity at 165 to 170 cm total length. Sex differentiation research has shown that levels of steroid hormones may be responsible for development of gonads and secondary sex organs. When near birth, females will enter nursery grounds. At birth, pups range in length from 56 to 75 cm, but some sources have found pups as small as 40 cm. Pup size may be related to mother size, environment, and litter size. Sandbar sharks are the slowest growing and latest maturing of all sharks.

Breeding interval: Sandbar sharks breed every 2 to 3 years, usually in the warmer months.

Breeding season: Mating occurs in warm months; months vary due to geographic location.

Range number of offspring: 1 to 14.

Average number of offspring: 5-12.

Range gestation period: 9 to 12 months.

Average time to independence: 0 minutes.

Average age at sexual or reproductive maturity (female): 7.5 - 8.2 years.

Average age at sexual or reproductive maturity (male): 8.2 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous

There is little information regarding any parental investment of sandbar sharks after birth. However, females invest heavily in protecting the young during their development before birth.

Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female)

The sandbar shark spends the majority of its time near the sea bottom, where it patrols continuously for prey (4), such as small bottom-dwelling fishes, molluscs and crustaceans (2). Whilst the diet of the adult consists primarily of fish, the pups appear to feed more on soft blue crabs (7). Despite its size and large triangular teeth, the sandbar shark has never been blamed for attacks on humans, preferring instead to stick to its live fish meals (2). Like most other members of the Carcharhinidae family, the sandbar shark is viviparous, giving birth to between 1 and 14 pups in each litter (2). The size of the litter varies depending on the size of the mother, with large females giving birth to larger litters (2). Pregnancy is estimated to last from 8 to 12 months (2), and appears to differ between geographical locations (8) (9). The time of year in which the pups are born also varies slightly, but all females move inshore to shallow nursery areas to give birth (2) (8) (9). These nursery grounds are separated from the normal ranges of adults (9), and presumably offer the young a calm, food-rich environment in which to begin their lives. The females leave these coastal areas soon after giving birth, while the young remain in the nursery grounds until winter (9), when they move into warmer and deeper water (2). A common feature of sharks is their slow growth rate and low reproductive output. Estimates of the age at which the sandbar shark matures range from eight to ten years in Hawaii (10), to between 12 and 15 years of age in the Northwest Atlantic Ocean (11). Females give birth every other year at most (2). Populations of sandbar sharks appear to segregate by age (6).

A management plan for the sandbar shark, involving catch quotas and size restrictions, was implemented in U.S. waters in 1993. Subsequently, the depleted western North Atlantic population has ceased declining and is beginning to show signs of recovery (1). Further reductions and size restrictions have been proposed to enhance the chances for population recovery; as even if the fishery was completely banned, the sandbar shark would still take several decades to recover (12). The lack of data on populations and catches from other regions is worrying, as the sandbar shark could be edging towards a more threatened status without us even knowing.

The most distinctive feature of this stocky, grey shark is its huge dorsal fin (3) (4), which increases its stability as it cruises the sea bottom in coastal areas. The sandbar shark belongs to the genus Carcharhinus, a word derived from the Greek “karcharos” meaning sharpen and “rhinos” meaning nose (3), although this species has a fairly rounded snout (2). The species name plumbeus comes for a Latin word meaning 'of lead' (3), presumably referring to its colouration, which is bluish to brownish-grey on the back, and lighter, or whitish, on the underside (2) (5).

The sandbar shark inhabits coastal waters, favouring water that is 20 to 65 metres deep (3), but occasionally venturing as down to depths of up to 1,800 metres (6). Only occasionally can its large dorsal fin be seen protruding from the water's surface, as the sandbar shark prefers remaining near the bottom (2). It commonly occurs in harbours, lagoons, muddy and sandy bays, and river mouths, but never moves into freshwater. It tends to avoid sandy beaches, the surf zone, coral reefs and other rough-bottom habitats (2).

Occurs in temperate and tropical waters, in the Western Atlantic, from Massachusetts to southern Brazil; in the eastern Atlantic from Portugal to Zaire; and in the Indo-Pacific from South Africa to the Galapagos and from Vietnam to New Caledonia. It also occurs in the Red Sea and Mediterranean (2) (4).

Classified as Lower Risk / Near Threatened (LR/nt) on the IUCN Red List (1).

The slow growth, late sexual maturity and low reproductive output of the sandbar shark are all biological factors that make this shark vulnerable to overfishing. In most areas of its range, the sandbar shark is an important component of shark fisheries. The flesh is consumed by humans, the thick skins are prized for leather, vitamin-rich oil is extracted from the liver, and the fins are sold to Asian markets for use in shark fin soup (2). Although comprehensive catch data of this species is lacking, it is known to be severely overfished in the western North Atlantic (1), indicating that populations could be similarly impacted in other parts of its range. The inshore habitats which are important nursery grounds for the sandbar shark may also be impacted by the activities of humans which alter and degrade the natural environment (12).

Red List Category & Criteria:

Endangered A4d (Regional assessment)ver 3.1

Year Published: 2016 Date Assessed: 2016-03-25 Assessor(s): Ferretti, F., Walls, R.H.L., Musick, J., Stevens, J., Baum, J.K., Bradai, M.N., Fergusson, I., Grubbs, D., Soldo, A., Vacchi, M. & Vooren, C.M. Reviewer(s): Dulvy, N.K. & Allen, D.J. Contributor(s): Fordham, S., Clò, S. & Buscher, E. Facilitator/Compiler(s): Walls, R.H.L. & Dulvy, N.K. Justification:
Mediterranean regional assessment: Endangered (EN)

The Sandbar Shark (Carcharhinus plumbeus) is long-lived, however with low fecundity and is consequently highly sensitive to overfishing. This species is an important component of shark fisheries in most areas of occurrence and has been intensively overexploited in both coastal and pelagic waters of the Mediterranean Sea for centuries. Catches have declined significantly along the Levantine coasts. Historically, the Sandbar Shark was regularly seen in fish markets of southern Sicily and was recorded in most coastal areas of the Mediterranean Sea. However, it has not been observed in these markets in recent years. Although the Gulf of Gabès, Tunisia, and theGulf of Gökovain Turkey appear to be important nursery grounds for this species, recent records in the Mediterranean Sea outside these areas are sporadic and there are none of gravid females. Past and future declines are estimated and projected to be of >70% over the three-generation period (69 years). Therefore, the Sandbar Shark is assessed as Endangered under Criterion A4d in the Mediterranean Sea, as it continues to be intensively fished with no signs of decreasing fishing effort in the region.Further research should be conducted on the population size and trend of the species, and management of target and bycatch fisheries is needed.

fieldmarks: A medium-sized gray shark with short rounded snout, an extremely tall triangular first dorsal fin with its origin over or anterior to the pectoral insertions, broad- and high-cusped, triangular serrated upper teeth without cusplets, usually 14/13-14 rows of anterolateral teeth, an interdorsal ridge, large pectoral fins, a moderately large dorsal with a short rear tip, and no conspicuous markings on fins. Medium to large, fairly stocky sharks (up to about 2.4 m but mostly smaller) with snout short and broadly rounded or broadly parabolic, internarial width 0.9 to 1.3 in preoral length. Eyes circular and moderately large, length 1.7-2.9%TL. Nostrils with very short, low, poorly developed anterior nasal flaps. Upper labial furrows short and inconspicuous. Hyomandibular line of pores just behind mouth corners not conspicuously enlarged. Gill slits short, 3rd 2.4-3.6% TL and less than a third of first dorsal base. Usually 14/13-14 rows of anteroposterior teeth in each jaw half but varying from 14-15/12-15; upper teeth with broadly triangular, strongly serrated, semierect to slightly oblique cusps merging smoothly into crown feet with slightly coarser serrations but no cusplets; lower teeth with erect, narrow serrated cusps and transverse roots. A narrow interdorsal ridge present. Pectoral fins large, semifalcate, with narrowly rounded or pointed apices, length of anterior margins about 17 to 22%TL. First dorsal fin very large and semifalcate, with pointed or narrowly rounded apex and posterior margin curving ventrally from fin apex; origin of first dorsal fin over or slightly anterior to pectoral insertions; inner margin of first dorsal moderately long, 2/5 of dorsal base or slightly less. Second dorsal fin moderately high, height 2.1 to 3.5% TL, inner margin short and 1.0 to 1.6 times height; origin of second dorsal over or slightly anterior to anal origin. 152-189 total vertebral centra, 82-97 precaudal centra. Colour gray-brown above, white below; tips and posterior edges of fins often dusky, but no conspicuous markings; an inconspicuous white band on flank.

Maximum possibly to 3 m but otherwise to 239 cm or less for adults; males maturing at 131 to 178 cm and reaching 224 cm; females maturing at 144 to 183 cm and reaching 234 cm; size at birth 56 to 75 cm.

An abundant, inshore and offshore, coastal-pelagic shark of temperate and tropical waters, found on continental and insular shelves and in deep water adjacent to them, and oceanic banks;common at bay mouths, in harbours, inside shallow muddy or sandy bays, and at river mouths, but tends to avoid sandy beaches and the surf zone, coral reefs and rough bottom, and the surface.Depths range from the intertidal in water barely deep enough to cover it to 280 m. Although common in inshore environments, it does not ascend rivers into fresh water. It favours the bottom, and normally is not seen at the surface unless travelling in water so shallow that its large first dorsal fin comes out of the water.As with several other wide-ranging carcharhinids this species has a number of allopatric populations in different areas. In the Western Atlantic Springer (1960) suggested that there are two stocks or subpopulations of sandbar sharks, a northern major one from the US Atlantic seaboard to the Gulf of Mexico and the eastern Caribbean, and a minor South American one from Trinidad eastwards and southwards to Brazil. Although this remains to be proven by tagging, Springer hypothesized that the separate Eastern Atlantic population of this shark was capable of contributing to the South American population via migration with the equatorial current across the Atlantic. [more...] Preferred temperatures in shallow water off Madagascar are 23 to 24°C; off the Hawaiian Islands these sharks occur in waters 24 to 27°C. Viviparous, with a yolk-sac placenta; number of young 1 to 14 per litter, with 5 to 12 common. Litter size varies directly with size of the mother, and in populations with smaller adults the litter size averages smaller. The size of young at birth varies considerably among different allopatric populations of this shark, including adjacent ones in the Western Atlantic, as does the size attained by adults. In this shark as in many other carcharhinids the size range of adults is relatively narrow, indicating virtually determinate growth after maturity. The gestation period is estimated as 8 to 12 months, commonly 9 months off Florida, and 11 to 12 months off South Africa and in the South China Sea. [more...] In captivity these sharks show growth rates that suggest maturation in as little as three years, but other estimates based on tooth replacement suggests 10 years for males and 13 for females. Springer (1960) suspected that sandbar sharks may mature in only two years, but on little real evidence. Presumably this is somewhere between 3 and 10 years.The sandbar shark is primarily a predator on relatively small bottom fishes, with some molluscs and crustaceans taken. [more...] It does not consume garbage and mammalian carrion as a rule, unlike some other members of its genus. Evidence from fisheries indicates that very fresh fish bait is greatly preferred by these sharks to stale or even fresh-frozen fish, and fish greatly preferred to mammalian meat. These sharks feed by day and night, more actively at night. It is thought that this shark is far more successful in obtaining a regular supply of food than larger carcharhinids such as Galeocerdo cuvier, Carcharhinus leucas and Carcharhinus obscurus ; this is reflected in greater number of sandbar sharks with full or nearly full stomachs, and liver weight, which shows much less fluctuation in sandbar sharks than in the three larger species. Data from captive individuals suggests that digestion is relatively rapid, and prey is largely digested after two days.It is thought that adult sandbar sharks are rarely eaten by other larger sharks and may be difficult prey for them (with the likely exception of the great white shark, which is known to eat adults of this species), but that the young are readily taken by other sharks, particularly the bull and tiger sharks, which feed on them in inshore areas.

This is an abundant inshore and offshore species where it occurs, and forms an important object of fisheries especially in the western North Atlantic, eastern North Atlantic, and South China Sea. USA have reported to FAO catch statistics for this species in Northwest Atlantic in 1988 (2 t) and 1992-1995 (55, 31, 21 and 1 t, respectively). No catch reported for this species to FAO for 1999 It is caught with longlines, hooks and lines, and set bottom nets and is also fished with rod and reel by sports anglers as a game fish. It is utilized fresh, fresh-frozen, smoked and dried salted for human consumption; the hides are prized for leather and other products; the fins are prepared as the base for shark-fin soup; and the liver is extracted for oil (rich in vitamins). Impact of fisheries The sandbar shark is taken commercially in coastal fisheries throughout its range and is also an important part of some sport fisheries. This species is very common in the small-scale shark fisheries of Eastern México where adults and subadults are commonly caught (Bonfil 1997). Sandbar sharks are also taken in the fisheries of Taiwan and Western Australia (Bonfil 1994), as well as in the Arabian Sea (Sivasubramaniam 1992). However, there are no abundance indices for any of these fisheries. Sandbar sharks are the second preferred shark in sport fisheries in the East Coast of the US (Hoff and Musick 1990) where some 750,000 individuals are killed annually (National Marine Fisheries Service 1993, cited by Musick in press). Because of the high quality of its flesh and its large fins, this is the most important commercial species in the shark fishery of the southeastern United States where an average of 550 t/y were taken in 1992-1995 (Rose 1998). Sandbar sharks have suffered a decline similar to that of dusky sharks in the US East Coast. Musick et al. (1993) documented a considerable drop in CPUE of the sandbar shark off Virginia. Ulrich (1996, cited by Castro et al. in press) reports a dramatic decline of sandbar shark abundance off South Carolina, from 4.73 sharks /100 hooks in 1983-84, to 0.39 sharks /100 hooks in 1994-95. Abundance indices from the US sport fishery of Virginia-Massachusetts decreased sharply from 1988 to 1996 and started rising only in 1997 (Brown 1998). A management plan for this and other species is in place in the US Atlantic since 1993. Recent strong reductions in the TAC seem to begin showing their positive effect as 4 out of 5 sandbar abundance indices show increasing trends since 1993 (Anon. 1998). Cliffet al. (1988) report that catch rates of sandbar sharks in the beach protection programme of Natal dropped from 2.3 to 0.7 sharks/km-net/year from the 1966-72 to the 1978-87 period. However, these authors point that factors other than net-induced mortality must be responsible for the change given the small netting effort in comparison to the overall range of the sandbar shark population in the region. Conservation Status : The sandbar shark has a very low intrinsic rebound potential (Smith et al. 1998) and can be easily depleted when fished carelessly. The IUCN Red List classifies sandbar sharks as Lower Risk/Near Threatened at the world level and the stocks in US waters of the Atlantic and Gulf of México as Lower Risk/Conservation Dependent (Camhiet al. 1998). Mooney-Seus and Stone (1996) consider sandbar sharks as Severely Reduced in US Atlantic waters and Data Deficient in the rest of the Atlantic and Pacific. Newborns and juveniles inhabit temperate coastal lagoons, thus habitat degradation and human encroachment further threaten some stocks (i.e. US Atlantic coast). Unrestricted sport and commercial exploitation through the 1970s and 1980s brought down the stocks of the US Atlantic coast to very low levels. Conservative catch quotas introduced through a management plan for the recovery of large coastal sharks in 1993 were further reduced in 1997 due to concerns over the recovery of sandbar sharks (Camhi et al. 1998). The abundance indices for this species show a slow increase since management came about but the stock is still a long way from recovery. The Western Australia commercial shark fishery exploits the younger age classes of the local sandbar shark population (Simpfendorfer 1998), but the breeding part of this stock is under protection through a no-take MPA (see dusky shark account). Additional information from IUCN database Additional information from CITESdatabase

A stout shark with a moderately long, rounded snout, high, triangular, saw-edged upper teeth, and an interdorsal ridge; 1st dorsal fin very large and erect (Ref. 5578). Grey-brown or bronzy with no prominent markings, white below (Ref. 5578). Fins plain or with slightly dusky tips (Ref. 5485).

Viviparous (Ref. 26281), placental (Ref. 50449), 1-14 pups in a litter; 56-75 cm at birth (Ref. 2334); gestation period of 12 months (Ref.58048). Distinct pairing with embrace (Ref. 205). Sexual dimorphism is evident in the thicker skin layer of maturing and adult females (Ref. 49562). This thickened skin may serve as protection from the 'bites' the female species receive from the males during precopulation and in the rugged conditions of the rock and coral environment where they live (Ref. 49562). Pups are born from Feb. to April in Northeastern Taiwan (Ref. 37027).

Oceanodromous. Migrating within oceans typically between spawning and different feeding areas, as tunas do. Migrations should be cyclical and predictable and cover more than 100 km.

Dorsal spines (total): 0; Dorsal soft rays (total): 0; Analspines: 0; Analsoft rays: 0

Occurs on the continental shelf (Ref. 75154).

Found inshore and offshore, on continental and insular shelves and adjacent deep water (Ref. 244). Common at bays, river mouths and in harbors; avoids sandy beaches and the surf zone, coral reefs and rough bottom, and surface waters (Ref. 244). Coastal-pelagic, but usually bottom associated at 1-280 m (Ref. 58302). Sometimes in oceanic waters (Ref. 9997). Known to make extended seasonal migrations in some parts of its range (Ref. 6871). Feeds mainly on bony fishes, also small sharks, cephalopods, and shrimps (Ref. 5578), rays and gastropods (Ref. 5213). Youngs feed heavily on crustaceans such as blue crabd and mantis shrimp (Ref. 93252). Viviparous (Ref. 50449). Sexual dimorphism is evident in thickness of skin layer of maturing and adult females (Ref. 49562). Females live as long as 21 year; males 15 years (Ref. 27549). Populations are segregated by age. Young readily kept in aquaria (Ref. 244). Utilized for human consumption, for leather and oil (Ref. 244). Marketed fresh, smoked, dried-salted and frozen; fins are valued for soup (Ref. 9987). Used in Chinese medicine (Ref. 12166). Records to 300 cm TL uncertain (Ref. 9997). TL to 300 cm (Ref. 26938). Angling: an inshore fish and a good light-tackle fighter (Ref. 84357).

fisheries: commercial; gamefish: yes

分布於全球各溫、熱帶水域。臺灣東部及東北部海域常見蹤跡。

主要以底拖網、流刺網及延繩釣捕獲，經濟價值高。肉質佳，可加工成各種肉製品；鰭可做魚翅；皮厚可加工成皮革；肝可加工製成維他命及油；剩餘物製成魚粉。

體呈紡錘型，軀幹頗粗壯。頭寬扁。尾基上下方各具一凹窪。吻端寬圓。眼圓，瞬膜發達。前鼻瓣短，發育不完全；無口鼻溝或觸鬚。口裂寬，圓弧形，口閉時上下頜緊合，不露齒；上頜齒寬扁三角形，邊緣具明顯鋸齒，齒尖直立或外斜，無小齒尖；下頜齒較窄而直立，內外側皆凹入，邊緣略具鋸齒。噴水孔缺如。背鰭2個，背鰭間存在明顯的隆脊，第一背鰭寬大，起點在胸鰭基底後端或稍前，後緣凹入，上角鈍尖，下角尖突；第二背鰭小，起點與臀鰭起點相對，後緣入凹，後角尖突；胸鰭大型，鐮刀形，後緣凹入，外角鈍尖，內角鈍圓，鰭端伸達第一背鰭基底後端；尾鰭寬長，尾椎軸上揚，下葉前部顯著三角形突出，中部低平延長，與後部間有一深缺刻，後部小三角形突出，尾端鈍圓。體背側灰褐色；腹側白色。鰭灰褐色，後緣較淡。

棲息於近海、外海大陸棚及島棚外圍之深海水域，但亦常出現於內灣、港灣或河川出海口，但會避開沙灘、珊瑚礁區或碎石激浪區，有時會巡游於大洋中。主要以硬骨魚類、其他鯊魚、魟、甲殼類、頭足類等生物為食。胎生，一胎可產下1-14尾幼鯊，剛出生之幼鯊體長可達65-75公分。

The sandbar shark (Carcharhinus plumbeus), also known as the brown shark or thickskin shark, is a species of requiem shark, and part of the family Carcharhinidae, native to the Atlantic Ocean and the Indo-Pacific. It is distinguishable by its very high first dorsal fin and interdorsal ridge. It is not to be confused with the similarly named sand tiger shark, or Carcharias taurus.

Found over sandy and muddy areas of coastal waters, including estuaries. May inhabit oceanic waters. Feeds on benthic animals, fishes, rays, gastropods, and squids (Ref. 5213). Viviparous; litter size 1-14 pups, born during midsummer (Ref. 5485); 56-75 cm at birth (Ref. 2334). Populations are segregated by age. Preferred water tempeatures range from 23 to 27°C. Potentially dangerous but has never been incriminated in any attack on people. Utilized for human consumption, for leather and oil. Marketed fresh, dried-salted and frozen; fins are valued for soup (Ref. 9987).

Feeds mainly on bony fishes, also small sharks, cephalopods, and shrimps

Massachusetts (Woods Hole, straying into Gulf of Maine) to southern Brazil

nektonic