Grey nurse sharks, also called sand tiger sharks, can be found in the Atlantic, Indian, and Pacific Oceans in temperate and tropical waters. They are found in warm seas, except for the eastern Pacific. They occur from the Gulf of Maine to Argentina in the western Atlantic, the coast of Europe to north Africa in the eastern Atlantic, in the Mediterranean sea, from Australia to Japan in the west Pacific, and off the coasts of South Africa.

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

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Nearly cosmopolitan in subtropical and temperate waters, generally at depths less than 60 m. Range includes the western North Atlantic (Nova Scotia to the northern Bahamas and Florida and Gulf of Mexico west to Texas; also Brazil to Argentina), the Atlantic coast of Europe to North Africa and the Mediterranean Sea, western Indian Ocean, and western Pacific Ocean; absent from the eastern Pacific Ocean (Castro 1983, Gilmore et al. 1983, Michael 1993, Hoese and Moore 1998). Perhaps the most common shark in coastal waters from Cape Cod, Massachusetts to Chesapeake Bay; free-swimming juveniles in the western Atlantic are restricted to temperate and warm-temperate waters, extending as far south as northern Florida Juveniles 109.3-157.7 cm total length have been recorded in neritic waters along the northern Florida coast and in the northern and northeastern Gulf of Mexico.

The dorsal side of grey nurse sharks is grey, the underside is a dirty white color. These are stout-bodied sharks with metallic brown or reddish colored spots on the sides. When a grey nurse shark pup is born it is typically between 115 and 150 cm. As they mature, grey nurse sharks can reach 5.5 meters, but an average size is 3.6 meters. Females are generally larger than males. Average weight is from 95 to 110 kg. A distinguishing characteristic of grey nurse sharks is that the anal fin and both dorsal fins are the same size. The tail is heterocercal, with a long, upper lobe and a shorter, lower lobe. These different lobes allow for great movement. The mouth bears razor like teeth and is long and slender, with pointed snout. Their elongated teeth are visible even when the mouth is closed, giving these sharks a menacing appearance. This has led many to believe that these are dangerous sharks, a reputation they don't deserve.

Range mass: 50 to 300 kg.

Average mass: 95-110 kg.

Range length: 6 (high) m.

Average length: 3.6 m.

Range basal metabolic rate: <190 to 311 cm^3 oxygen/hour.

Average basal metabolic rate: 239 cm^3 oxygen/hour.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: female larger

Records of the great white shark Carcharodon carcharias (Linnaeus) (Lamniformes: Lamnidae) in the Persian/Arabian Gulf (hereafter referred to as “The Gulf”) are limited to a single report from Kuwait, in the northwest Gulf, which has subsequently been noted in key references (e.g. Compagno, 2001). Khalaf (1987) recorded C. carcharias based on an observation of a mounted specimen in Kuwait Science and Natural History Museum on a visit there in March 1987. The specimen is reported as being a female C. carcharias of 3m in length, caught off Kuwait ’s coast and supplied to the museum on the 14th of April 1984. A black and white photograph of the anterior portion (from just posterior of the pelvic fins) was included in Khalaf’s account (Fig. 1 here), but no measurements or morphological data were presented.

The present authors examined the photograph and identified the specimen as Carcharias taurus Rafinesque (Lamniformes: Odontaspididae) based on the first dorsal fin origin being well behind the inner margins of the pectoral fins (cf. over the pectoral inner margins in C. carcharias ), the first dorsal fin insertion being about over the pelvic fin origin (cf. being well ahead of pelvic fin origin), a short flattened snout (cf. moderately long conical snout), moderately long gill openings not extending onto the dorsal surface (cf. long gill openings), and characteristic protruding teeth. The photograph presented did not allow for examination of the caudal region or for effective examination of colouration.

Carcharodon carcharias has been recorded from a wide range of habitats and with an extensive distribution ranging from the equatorial tropics to the sub-Arctic, and from the intertidal down to the continental slope (Compagno, 2001). Cliff et al. (2000), Compagno (2001), and Zuffa et al. (2002) report white sharks from the tropical Western Indian Ocean off Mozambique and Madagascar north to Tanzania and Kenya and including the Seychelles, Réunion and Mauritius. There is therefore no theoretical reason why this species should not occur in the Persian Gulf or the wider northwestern Indian Ocean, although the nearest confirmed record is from Sri Lanka and possibly the Red Sea (Compagno, 2001). In addition, there are unconfirmed, anecdotal records of white sharks from the Gulf of Aden coast of Yemen, Djibouti and northern Somalia (Conan Doyle, 1963).

Gubanov & Schleib (1980) reported C. taurus as sometimes being encountered in Kuwait waters, although Krupp et al., (2000) noted that there was no material provided to support this. Krupp et al., (2000) reported the first record of C. taurus from The Gulf supported by reference material based on a 2.98m specimen caught off Abu Halifa, Kuwait , in 1997. The C. taurus reported here predates this by thirteen years.

• Marine

• Marine

• Marine

• Marine

Grey nurse sharks are found in temperate and tropical waters. They are typically found in shallow waters, such as shallow bays, surf zones, and near coral or rocky reefs. They have been sighted in waters as deep as 191 meters, but will most likely be seen in the surf zone to a depth of 60 meters. They are usually found near the bottom of the water column.

Range depth: 2 to 191 m.

Average depth: 60 meters m.

Habitat Regions: temperate ; tropical ; saltwater or marine

Aquatic Biomes: reef ; coastal

Other Habitat Features: estuarine

Habitat Type: Marine

Comments: Ranges from turbid coastal waters along shore to deeper waters of upper continental and insular slopes; usually found close to the bottom near shore, often in very shallow water (< 4 m) (Castro 1983). Common in neritic waters off northeastern Florida at 5-12 m depth. Nursery grounds are littoral, temperate waters, but do not include embayments or low salinity areas; young are exposed to predation by adult sharks of these areas (Gilmore et al. 1983). Common in temperate and tropical seas on or near coral and rocky reefs (Michael 1993). Often found amid large schools of smaller baitfish (which it occasionally eats).

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Migrates between nearshore waters (summer) deeper waters (winter) (Castro 1983). Female groups make coordinated seasonal coastal movements possibly for breeding, gestation, and eventually parturition (Gilmore et al. 1983).

Grey nurse sharks have a range of prey, including bony fish, rays, lobsters, crabs, squid, and other small sharks. Grey nurse sharks sometimes hunt cooperatively, chasing fish into small groups and then attacking them. Grey nurse sharks, like other sharks, have been known to attack at random during feeding frenzies, where a large number of prey is found together. In feeding frenzies sharks rely heavily on their electroreceptors, attacking everything in close vicinity.

Animal Foods: fish; mollusks; aquatic crustaceans

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

Comments: Considered a voracious eater, feeding on many species (alewives, bluefish, flatfishes, mackerel, menhaden, invertebrates); its teeth are adapted for grasping smaller prey. Known to gather in groups of 3-4 to herd and prey on a school of fish.

Grey nurse sharks help to regulate prey populations. Different species of lampreys (Petromyzontidae) prey on these sharks in a parasitic relationship, whereby the lamprey attaches to the shark, and extracts blood and other nutrients through a wound. These sharks also have mutualistic relationships with pilotfish (Naucrates ductor), which clean their gills and, in exchange, get to eat the scraps of food left behind in the gills.

Mutualist Species:

• pilotfish (Naucrates ductor)

Commensal/Parasitic Species:

• lampreys (Petromyzontidae)

The only know predators of adult grey nurse sharks are humans. Human hunting has caused population declines, both as a result of shark fishing and persecution because their fierce appearance has caused them to be mistaken for other, more dangerous, species of sharks. They are also accidentally caught in commercial fishing nets. Young sharks are eaten by other sharks.

Known Predators:

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

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 21 - 80

Comments: Exact number of occurrences is unknown; likely to be many based upon wide distribution in the Atlantic Ocean.

2500 - 10,000 individuals

Comments: Global abundance is unknown. Often common in warm temperate regions; common from Cape Cod to Delaware Bay during the warmer months. Although first reported from Texas in the 1960s, this species does not appear to be uncommon in the northwestern Gulf of Mexico (Hoese and Moore 1998). It is more common along the eastern coast of Florida than the eastern Gulf of Mexico (Gilmore et al. 1983).

The causes of mortality are poorly known because they have low commercial value and are often difficult to obtain for study (Hoenig and Walsh 1983). Vertical lesions, specifically regions of swelling along the vertebral column, have been recorded from captured specimens (Hoenig and Walsh 1983).

Communication among grey nurse sharks is not well understood. Sharks in general are sensitive to electrical and chemical cues.

Grey nurse sharks, and other species of sharks, have pores on their ventral surface. These pores are instrumental in detecting electrical fields, which help them to detect and locate prey and may help in navigating using the earth's magnetic field.

Perception Channels: visual ; tactile ; chemical ; electric

It takes a grey nurse shark pup between 6-9 months to develop in the uterus of a female. Young nurse sharks develop a jaw and teeth very early their development and some eat their siblings while still developing within their mother, a phenomenon known as intra-uterine cannibalism. It is uncertain how long it takes grey nurse sharks to reach maturity, but maturity is estimated at between 5 and 13 years. Sharks continue to grow throughout their lives.

Development - Life Cycle: indeterminate growth

Little is known about the lifespan of ocean dwelling grey nurse sharks, however those held in captivity live to an average age of thirteen to sixteen years. It is believed that those in the wild live longer still.

Range lifespan

Status: wild: 35 (high) years.

Range lifespan

Status: captivity: 16 (high) years.

Males outnumber females by a 2:1 ratio and multiple males will copulate with a single female. A dominance hierarchy has only been observed in captivity, with the oldest males copulating first.

Mating System: polygynandrous (promiscuous)

Mating occurs in November and October. The gestation period will take anywhere from six to nine months. Females give birth in early spring near coastal, rocky reefs. Caves inhabited by these sharks are also used as breeding grounds and, if disrupted, their breeding may be interrupted. Female sharks bear young once every two years, with a maximum of two shark pups at birth, one from each uterus. Grey nurse sharks are ovoviviparous which means that eggs develop inside of the female in each uterus. Young hatch from the eggs and are retained in the uteri until they are fully developed. Females have hundreds of eggs inside the uterus. When an egg is fertilized the shark pup begins to grow and, at 55 mm, develops a jaw and teeth. This shark then eats the other developing embryos during its 6 to 9 month gestation (intra-uterine cannibalism).

Males mature at a length of 1.95 meters, or 4-5 years in age, and females mature at 2.2 meters, or 6 years in age.

Breeding interval: Grey nurse sharks bear young once every two years.

Breeding season: Shark pups are usually born in early spring (March and April).

Range number of offspring: 1 to 2.

Average number of offspring: 1.

Range gestation period: 6 to 9 months.

Range age at sexual or reproductive maturity (female): 5 to 13 years.

Average age at sexual or reproductive maturity (female): 7-8 years.

Range age at sexual or reproductive maturity (male): 5 to 13 years.

Average age at sexual or reproductive maturity (male): 7-8 years.

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

A pup will be born approximately 115-150 cm in length. This shark is able to fend for itself and live without parental care. Intra-uterine cannibalism ensures plenty of energy to the developing pup, resulting in a well-fed and well-developed offspring.

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

Winter-spring is the breeding period off the Florida east coast (Gilmore et al. 1983). Individuals may aggregate in specific areas for mating (Michael 1993). Development is ovoviviparous. The gestation time is very long (10.5 months) (Pratt and Casey 1987). Individuals are about 65-110 cm total length at birth (Gilmore et al. 1983; Michael 1993). Age and growth data are lacking except for captive specimens (Branstetter 1990). The birthing season in Florida waters occurs during November through February. Adult females produce only two extremely large (> 100 cm) young per mating season (embryos are oviphagous and cannibalistic) (Castro 1983, Gilmore et al. 1983). Females reach maturity at 237 cm total length (Pratt and Casey 1987).

Grey nurse sharks were the first shark species to be protected by law. Grey nurse sharks are cited as being critically endangered in the Commonwealth Legislation (Australia). They are also considered endangered in New South Wales. The Queensland Government is hoping to provide a listing in the Nature Conservation Act of 1992 which will give these sharks additional protection. The National Marine Fisheries service in the United States prohibits hunting of these sharks. The IUCN lists grey nurse sharks as a vulnerable species on the red list (last evaluated in 2000). CITES does not have a listing for them, and is the most recently updated (2005). The fact that these sharks live in shallow, accessible waters, have a fierce appearance, and have a low reproductive rate, has contributed to declines in populations. Population declines worldwide are estimated at 20% in the last 10 years.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: critically endangered

Canada

Rounded National Status Rank: NNR - Unranked

United States

Rounded National Status Rank: NNR - Unranked

Rounded Global Status Rank: G3 - Vulnerable

Reasons: Wide, nearly cosmopolitan distribution in subtropical and warm temperate oceans; number of extant occurrences and global abundance are not well documented; no known protected occurrences and no specific fisheries protection afforded; considered extremely susceptible to overfishing due to based on life history characteristics, particularly very low reproductive output.

Other Considerations: Slow growth (Pratt and Casey 1987, Branstetter 1990), delayed reproduction, and very low reproductive output (Compagno 1990) make this species vulnerable to overexploitation.

Global Short Term Trend: Relatively stable (=10% change)

Comments: Insufficient information exists to determine population trends; assumed to be stable but may be declining because of fishing pressure.

Degree of Threat: C : Not very threatened throughout its range, communities often provide natural resources that when exploited alter the composition and structure over the short-term, or communities are self-protecting because they are unsuitable for other uses

Comments: Principal threat is fishing, although habitat degradation in coastal waters and nursery areas may affect juveniles. Generally fished wherever it exists; regularly caught in substantial amounts (Compagno 1990). Caught with hook-and-line, gill nets, and trawls for meat, fishmeal, liver oil, fins, and hide. Often caught by sport anglers and was formerly targeted by fishermen in Australia and South Africa. Much of catch is relatively minor bycatch for more fecund teleosts. Mostly caught as bycatch in Japanese tuna longline vessels (Taniuchi 1990).

Biological Research Needs: More research on population dynamics and reproductive biology is needed.

Global Protection: None. No occurrences appropriately protected and managed

Comments: No known protected occurrences. In 1989, the National Marine Fisheries Service judged large coastal sharks (including the tiger shark) to have been overfished by 2,348 metric tons and in 1990 by 1,431 metric tons. As a result, the National Marine Fisheries Service set annual poundage quotas, called total allowable catches for each of the heavily fished groups. In 1993 the total allowable catch for large coastal sharks was set at 2,436 metric tons plus a 464 metric tons recreational quota. The total allowable catch for large coastal sharks was set to be adjusted annually upward at 80% of the annual surplus production. This strategy was predicted to allow for a population increase leading to a return of the natural Maximum Sustainable Yield by the year 2000 (Burgess 1998). Sport anglers were restricted to two sharks per boat per trip for combined large coastal and pelagic sharks. Sale of recreationally caught sharks was prohibited (Burgess 1998). Finning of sharks by commercial and recreational fishermen was prohibited. In addition, a system of data collection and reporting was partially implemented (Burgess 1998). Still this plan has underestimated the recovery of the stocks (Burgess 1998). The total annual take of large coastal sharks was reduced to a total of 2,570 metric tons in 1994 and additional restrictions may be forthcoming (Burgess 1998).

Needs: Occurrences should be protected to ensure long-term survival.

Grey nurse sharks are known for their fierce appearance and have gained an undeserved reputation as a man-eater in Australia. These sharks are not generally aggressive, but have been known to bite. Their bites can inflict serious damage because of their size and their dangerous teeth. They are sometimes tangled in fishing nets.

Negative Impacts: injures humans (bites or stings)

Shark teeth are lost frequently and are prized gifts in many regions of the world. Shark is a delicacy that is eaten in many areas.

Positive Impacts: food ; body parts are source of valuable material; ecotourism ; research and education

Comments: Not considered to be of economic importance and generally not considered dangerous to humans.

Comments: Although some recent authors recognize Odontaspis, the senior synonym, and Carcharias as congeneric, Nelson (2004) follows Compagno (1999) in considering Carcharias to be a valid genus.

Also known as gray nurse shark and spotted raggedtooth shark (Compagno 1990).