SHARKS & RAYS OF BIMINI
BIGEYE SIXGILL SHARK
Hexanchus nakamurai
Family: Hexanchidae
Description: counter shaded with dark dorsal surface and much lighter ventral surface. Most unique feature is having 6 gills, instead of 5 like most other sharks. A fairly slender shark with a narrow head, large eyes, and a deep notch on upper lobe of caudal fin.
Size: maximum size is 180 cm.
Weight: approximately 20 kg.
Sexual maturity: males are mature are 123 cm and females at 142 cm.
Reproduction: aplacental viviparous with 13-26 pups per litter.
Average life span: unknown
Distribution: found around world in small patches. Areas include the Bahamas, Australia, and Madagascar.
Diet: small to medium bony fish and crustaceans.
Status: data deficient
Human pressure: sometimes accidentally taken as bycatch, but a relatively rare shark.
BLACKNOSE SHARK
Carcharhinus acronotus
Family: Carcharhinidae
Description: typical carcharhinid with a black nose and a darkened second dorsal and caudal tip. Second dorsal is located above anal fin.
Size: max 200 cm total length
Weight: max reported weight 18.9 kg
Sexual maturity: females mature around 100 cm TL with males maturing between 97 and 106 cm TL. Age of maturity varies between populations. In Gulf of Mexico males mature around 5 years and females around 6 years. Individuals mature faster in Atlantic waters, reaching this milestone at 4.3 years for males and 4.5 years for females.
Reproduction: placental viviparous, brood size 7-18
Average life span: Varies between populations. In US South Atlantic waters individuals are estimated to live up to 19 years.
Habitat: Inhabits coastal regions living over sand beds and coral reefs. Stays in water up to 64 meters deep.
Distribution: Found along coastlines from the Southern USA to south Brazil. Inhabit all coastlines in between, including all of Mexico, Central America, and islands in the Caribbean Sea.
Diet: feed on small bony fishes and crustaceans
Status: near threatened
Human pressure: Previously exploited for its oil and hide used as leather. Lemons are often caught by anglers for fishing tournaments due to their size and the juveniles are found to be hardy and can feed in captivity, therefore have been exhibited in aquaria. They are also caught by commercial fisherman for their meat and fins.
BLACKTIP SHARK
Carcharhinus limbatus
Family: Carcharhinidae
Description: black tips found on first and second dorsal fin, pectoral, pelvic fins and lower caudal lobe a long with a white streak on its flanks. Stout bodied with a long pointed snout and lacks an interdorsal ridge.
Size: rarely exceeds 195 cm.
Weight: Up to 46 kg
Sexual Maturity: 145 cm for males, 156 cm females
Reproduction: placental viviparous, gestation period 340 days, 4-6 pups
Average life span: Unknown
Habitat: predominantly found in shallow coastal waters and uses inshore waters of Carolina as nurseries during summer.
Distribution: found in subtropical and tropical waters. In the western Atlantic, it ranges from New England to Brazil. Also found in the Eastern Pacific but believed to be a separate population thus may even be a different species.
Diet: consists of small bony fish and small elasmobranchs, sting rays and squid.
Status: near threatened
Human pressure: commercially and recreationally very important, often sold for meat in fish markets and is known by recreational fisherman as a great fighting fish.
BULL SHARK
Carcharhinus leucas
Family: Carcharhinidae
Description: aggressive and territorial nature with a short, stout body, small eyes with limited vision, lack of interdorsal ridge. Bull sharks can live in freshwaters by increasing their urine production which reduces the concentration of salt and urea in their blood and allows them to adapt to various levels of salinity
Size: 210 - 340 cm Maximum 330 cm
Weight: 90-230 kg
Sexual Maturity: 220 cm in males, 230 cm in females.
Reproduction: viviparous, young are born live and free swimming, 1-13 pups, gestation 1 year
Average life span: at least 30 years, possibly up to 50.
Habitat: shallow warm waters as well as brackish and freshwater rivers and lakes
Distribution: in the Atlantic found from Massachusetts to Southern Brazil and from Morocco to Angola. In the Indian Ocean found from South Africa to Kenya, India and Vietnam to Australia.
Diet: oceanic diet consists of bony fish, dolphins, sting rays, sea turtles, other sharks, crustaceans and molluscs. Freshwater diet consists of shrimps, squid, crabs, sea urchins and tarpon
Status: near threatened
Human pressure: fished for meat, hides and oils
CARIBBEAN REEF SHARK
Carcharhinus perezi
Family: Carcharhinidae
Description: large and broad snout, interdorsal ridge from rear of first dorsal to front of second dorsal fin, long gill slits with the third slit lining up with the front of the pectoral fin. Dark grey colouration above with whitish coloration on the underside and dusky coloured fins.
Size: 200 -250 cm, max 300 cm
Weight: 70 kg
Sexual Maturity: 170 cm in males, 190 cm in females
Reproduction: viviparous, average brood size 4-6, gestation is 1 year
Average life span: unknown
Habitat: shallow waters specifically coral reefs, known as a bottom dwelling species
Distribution: throughout the tropical Western Atlantic ocean, mainly the Caribbean Sea
Diet: consists mainly of bony fishes and cephalapods
Status: near threatened
Human pressure: very little commercial interest.
GREAT HAMMERHEAD SHARK
Sphyrna mokarran
Family: Sphyrnidae
Description: wide cephalofoil (hammer) with a straight front margin with medial and lateral indentations, tall prominent sickle shaped first dorsal fin
Size: 400 - 600 cm
Weight: 230 kg
Sexual maturity: 2.3 m
Average life span: 20-30 years
Habitat: found in waters in the range of 1-80m mostly around coral reefs, as well as lagoons, island terraces and continental shelves.
Distribution: tropical and warm temperate waters worldwide between the latitudes of 40N and 37S
Diet: bony fish, cephalopods, small sharks, crustaceans with favourite prey being rays and skates
Reproduction: viviparous, breed once every 2 years, gestation period 11 months, 6-55 pups
Status: endangered
Human pressure: Heavily fished for fins used in shark fin soup, skin is used for leather, liver oil for vitamins and carcasses used for fishmeal. Often caught indirectly as bycatch in commercial fisheries.
Other info: believed its cephalofoil is an adaption for prey handling and delivers a powerful blow disabling its prey before pinning it down using its head. When hunting, they swing their head from side to side to pick up electrical signatures of rays buried in the sand.
LEMON SHARK
Negaprion brevirostris
Family: Carcharhinidae
Description: yellow coloration, first and second dorsal fin of similar size, flattened head, short broad snout. Neonates are bluish grey with white undersides and black fin edges whilst juveniles are yellowish brown/ grey above with yellow undersides.
Size: 300cm
Weight: 160kg
Sexual maturity: 245 cm in males based on clasper calcification at 11.6 years and 235-245cm in females at 12.7 years.
Reproduction: placental viviparous, brood size 7-18
Average life span: data unknown, at least 20 years.
Habitat: found in tropical and subtropical waters. Juveniles are known to remain in nurseries along shallow beaches, sea grass flats and around mangroves for years for ease of foraging and protection against predation. Their home range increases with size and they tend to venture into deeper waters as they grow larger.
Distribution: Eastern Pacific from Gulf of California to Ecuador and Western Atlantic from New Jersey to Brazil.
Diet: feed on small bony fishes and crustaceans.
Status: near Threatened.
Human pressure: previously exploited for its oil and hide used as leather. Lemons are often caught by anglers for fishing tournaments due to their size and the juveniles are found to be hardy and can feed in captivity, therefore have been exhibited in aquaria. They are also caught by commercial fisherman for their meat and fins.
MANTA RAY
Manta birostris
Family: Myliobatidae
Description: very large rays with triangle pectoral fins and a large head. Unique to the manta ray are its head and mouthparts, which give it a horned appearance.
Size: a maximum disc width (DW) of 700 cm has been validated but historical evidence suggests much larger creatures, up to 910 cm DW, have existed.
Weight: can reach over 1300 kg.
Sexual maturity: the size maturity is reached at varies but males have been shown to mature at 400 cm DW with mature females being slightly larger.
Reproduction: little to no information regarding reproductive ecology.
Average life span: estimates put the minimum lifespan at around 40 years.
Distribution: found throughout the entire world in tropical and temperate waters.
Diet: a very iconic filter feeder whose sustenance is primarily made up of zooplankton.
Status: vulnerable
Human pressure: bycatch is a major issue impacting the global health of the Manta ray. Certain fisheries do target the animal; these fisheries find relatively high success due to the ease of capture.
NIGHT SHARK
Carcharhinus signatus
Family: Carcharhinidae
Description: snout longer than the mouth width and large eyes with a noticeable green pupil. A small first dorsal and a low interdorsal ridge.
Size: Up to 300 cm
Sexual maturity: estimated males 185-190 cm and 200-105 cm for females
Weight: 135 kg
Average life span: unknown
Habitat: found in shallow marine waters around coral reefs.
Distribution: pelagic species found in deep tropical waters of the western Atlantic from Argentina to Delaware and along the west coast of Africa and the Gulf of Mexico and along the coast of Southern Brazil. Abundant in the deep waters of Cuba and Straits of Florida.
Reproduction: placental viviparous, brood size 10-20, gestation 12 months
Diet: unknown
Status: vulnerable
Human pressure: In the 1940s when shark fishery was at its peak the night shark was exploited by Cuban fisheries due to its high vitamin A content in its liver oil. There was a high mortality in the 1970s as bycatch due to swordfish and tuna fishery thus numbers have declined. Stated as protected in the US since 1997, although they continue to be caught as bycatch as the fish share the same habitat.
NURSE SHARK
Ginglymostoma cirratum
Family: Ginglymostomatidae
Description: enlarged rounded pectoral fins used as appendages to move around the sea bottom and rounded dorsal fins. Caudal fin can be over a quarter of the whole body length and lacks a lower lobe. Has a small mouth with fleshy, sensory projections called barbels and a pharynx (muscular cavity) used to suck in food.
Size: 220 - 270 cm
Weight: 75-110 kg
Sexual maturity: 223 - 231 cm Females, 215 cm Males
Reproduction: ovoviviparous, gestation 6 months, pups 21-50
Average life span: 25 years
Habitat: resting underneath ledges and in caves and crevices during the day. Described as a nocturnal species often seen lying on top of each other in large groups during the day.
Distribution: found in the Atlantic and the Eastern Pacific in tropical and subtropical waters. Common in shallow waters of the West Indies, South Florida and Florida Keys.
Diet: fish, molluscs and crustaceans
Status: data deficient
Human pressure: liver oil used as fuel and by commercial sponge fishers, skin used as leather
SILKY SHARK
Carcharhinus falciformis
Family: Carcharhinidae
Description: a snout shorter then mouth width, interdorsal ridge, low sloping first dorsal fin and second dorsal fin with a very long posterior free rear tip. Colouration is bronze brown with a white underside and dusky tips of pectoral fins.
Size: max ~300cm
Weight: 39 - 55 kg
Sexual Maturity: 210 - 220 cm and 6 - 7 years old in males, 225 - 232 cm and 9 years of age.
Reproduction: placental viviparous 4-12 pups gestation 1 year nurseries in open waters of Bahamas.
Average life span: unknown, at least 13 years.
Habitat: Found in shallow marine waters around coral reefs
Distribution: Warm tropical and sub tropical oceanic and coastal waters. East coast of the United States, most commonly seen from South Carolina to Gulf of Mexico.
Diet: Small fishes primarily yellowfin tuna, squid and crabs.
Status: vulnerable
Human pressure: Caught as bycatch by tuna and swordfish fishery. Exploited by shark fisheries in Japan, Maldives and Sri Lanka, fished for its meat, oil, and fins. Also caught by recreational anglers.
SMALLTOOTH SAWFISH
Pristis pectinata
Family: Pristidae
Description: most unique feature is flat blade-like rostrum with 24 to 32 pairs of teeth. Large caudal tail that moves side-to-side, more similar to a shark than a ray. Large pectoral fins are flattened having a very similar body shape to a guitar fish.
Size: maximum recorded size is 760 cm.
Weight: maximum published weight is 350 kg.
Sexual maturity: females over 400 cm and slightly less for males.
Reproduction: aplacental viviparous bearing 15-20 pups
Average life span: unknown
Distribution: found from North Carolina, throughout Gulf of Mexico and the Caribbean sea all the way to the coast of Argentina.
Diet: feeds on small fish, mollusks, and possibly crustaceans .
Status: critically endangered.
Human pressure: since populations are doing so poorly, the Smalltooth sawfish are unlikely to be intentionally targeted since the catch per unit effort would be so low. The sawfish can still be unintentionally captured as it becomes easily entangled with its long rostrum. The animal has historically been targeted for this valuable body part and sometimes its fins as well.
SOUTHERN STINGRAY
Hypanus americanus
Family: Dasyatidae
Description: A benthic stingray with pectoral fins connected to head and tail producing a diamond shape. D. Americana is often black but can also be green or brown. Large spiracles on top with 5-gill slits found on the ventral surface. Counter shaded with a soft white belly. Large, venomous, barb found on whip like tail.
Size: 150 cm disc width (DW)
Weight: 97 kg
Sexual maturity: Females are approximately 75 to 80 cm DW with males only being 52 cm DW.
Reproduction: 2 to 10 pups born after a period of 4.5 to 7.5 months.
Average life span: Data Unknown
Distribution: Found along the eastern coast of the North, Central, and South America with a heavy concentration throughout the Caribbean Sea
Diet: has been investigated in multiple countries to show a diet primarily consisting of shrimp, crabs, and certain bony fish.
Status: data deficient.
Human pressure: population in the United States appears to be healthy but little information is available for rest of species. Not listed as Least Concern because other geographic regions unintentionally target this animal and occasionally harvest it.
SPOTTED EAGLE RAY
Aetobatus narinari
Family: Myliobatidae
Description: a very unique and beautiful animal. Black disc covered in small white dots or ovals. Animal is pelagic and counter shaded with a white belly. Perhaps the most unique feature of the spotted eagle ray is the duck billed snout used for digging in the sand for prey. Long whiplike tail with anywhere from 2-6 spines.
Size: max disc width (DW) 330 cm.
Weight: max recorded 230 kg.
Sexual maturity: females reach maturity over 150 cm DW and males at 130 cm DW (between 4-6 years).
Reproduction: : 1 to 4 pups per litter with a gestation period around 12 months, reproduction occurs through aplacental viviparity.
Average life span: more investigation on life history required.
Distribution: worldwide distribution, especially in warm and temperate waters.
Diet: feeds mainly on mollusks and crustaceans occasionally preying on bony fish.
Status: near threatened
Human pressure: minor fishing importance to humans.
TIGER SHARK
Galeocerdo cuvier
Family: Carcharhinidae
Description: broad and bluntly rounded noses with distinctive striped markings on their body that fade with age.
Size: 300-400 cm (largest on record 549 cm)
Weight: up to 1000kg
Sexual Maturity: males 290cm Females 300cm
Reproduction: ovoviviparous, gestation is 14-16 months and a single shark can produce from 10-80 pups
Average life span: at least 27-37 years.
Habitat: found in a wide range of habitats; clear waters on the shallow banks, coral reefs, deep water in the Gulf Stream and turbid estuaries and bays.
Distribution: found worldwide in temperate and tropical waters, open ocean and shallow waters.
Diet: wide range of prey species, sea turtles, rays, bonyfishes, dolphins, squid, crustaceans, other sharks
Status: near threatened
Human pressure: fished for their fins, skins and flesh and their liver contains vitamin A processed into vitamin oil
YELLOW STINGRAY
Urolophus jamaicensis
Family: Urotrygonidae
Description: a small oval shaped stingray. Classified in the family Urotrygonidae, commonly known as the American round stingrays. Coloration is unique with a sandy-tan base layer, on top of this tan layer are multiple yellow circles, sometimes filled in with dark colors.
Size: maximum size recorded is 70 cm total length (TL) and 36 cm disc width (DW).
Weight: not rigorously documented, although due to small size, estimates put the weight well below 20 grams.
Sexual Maturity: Limited information but data suggests 20 cm TL required for sexual maturity.
Reproduction: Aplacental viviparity bearing 2 to 5 pups. Little known about reproductive age, periodicity, and gestation time.
Average life span: Data unknown
Distribution: Relatively limited distribution. Found in the Caribbean Sea to the Northern coast of South America. Range extends to North Carolina.
Diet: Small invertebrates, crustaceans, and mollusks.
Status: Least concern.
Human pressure: Certain commercial fisheries unintentionally target The Yellow Stingray but more research must be conducted to gauge the effect of this on the species. When directly targeted, the species is most often taken for the aquarium trade. The yellow stingray could be at further risk if more sea grass habitats are destroyed.