Atlantic Nurse Shark

About the Atlantic Nurse Shark

The Atlantic Nurse shark, also known as the Nurse shark or Cat shark, is a coastal species found in tropical and subtropical waters along continental and insular shelves. The species occurs in the Western Atlantic from North Carolina to southern Brazil, including the Gulf of Mexico and the Caribbean Sea. In the Eastern and Southeast Atlantic, it ranges from Morocco to Angola. Atlantic Nurse Sharks are bottom-dwelling predators that usually rest during the day on sandy bottoms, inside caves, or in rocky crevices. They may gather in groups and sometimes lie close together or on top of one another.

Their population has declined over the years because they have been targeted for their skin, while their meat is commonly transformed into animal food. They are extremely vulnerable to coastal fisheries, where they are caught both accidentally as bycatch and intentionally in gill-nets and longlines. Their sedentary and docile behaviour also makes them easy targets for spearfishers as they often remain in shallow coastal waters near reefs.

Biology

The Atlantic Nurse shark is yellow-brown to grey-brown in colour and can be identified by the two moderately long barbels near its nostrils, which help it detect prey on the seafloor. Its mouth is also positioned well in front of the eyes, giving the shark a broad, flat head. Its two dorsal fins are broadly rounded with the first one slightly larger than the second. The tail fin is long, accounting for about 1/4 of the sharks’ total length. They have 30 to 42 upper teeth and 28 to 34 lower teeth arranged in several replaceable rows.

Male Atlantic Nurse Sharks reach sexual maturity at about 210 to 214 cm (82.7–84.3 in), while females mature between 230 and 240 cm (90.6–94.5 in). The typical length of an adult is 230–245 cm (90.5–96.4 in), but the maximum recorded length is about 3.08 m (10.1 ft). Adult mass ranges from 70 to 114 kg (154–251 lb) and they can live up to 35 years.

Reproduction

The Atlantic Nurse Shark is ovoviviparous. The embryos develop inside egg cases within the mother’s uterus and receive nourishment from yolk sacs. Females usually give birth during late spring and summer. Gestation lasts five to six months and each litter contains around 20 to 30 pups measuring 27– 30 cm (10.6–11.8 in). After giving birth, females wait about 18 months before reproducing again. Male Atlantic Nurse sharks may mate with many females over several weeks.

Behaviour

Atlantic Nurse sharks are docile and not aggressive towards humans. They are strong swimmers, but they rely primarily on their sense of smell to locate prey because their eyesight is relatively poor. The species is nocturnal and spends much of the day resting on the seafloor.

Atlantic Nurse sharks use powerful suction-feeding to capture prey. Their diet includes fish, stingrays, mollusks, octopuses, squids, clams and crustaceans. They occur in depths ranging from 0 to 130 m (0–426 ft), but are most often found in shallower waters ranging from 0 to 35 m (0–115 ft). They hunt alone at night, but often return at dawn to the same resting sites, where they gather in groups or piles during the day.

Conservation

The Atlantic Nurse Shark is classified as vulnerable on the IUCN Red List. There are currently no reliable estimates of its global population size. In the United States, nurse sharks are included in a federal management plan with measures such as quotas and seasonal closures.

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Atlantic Nurse Shark Gallery