Grey Nurse sharks - habit and habitat

Grey Nurse shark, Carcharias taurus The food Chain

Grey nurse sharks eat a wide range of small fish, squid and crustaceans. They hunt cooperatively and can round up schools of fish. Their lanceolate teeth with characteristic lateral cusplets are well suited to holding and piercing slippery prey rather than cutting. Their teeth are shorter towards the back of the mouth. Grey nurse sharks are by no means at the top of the food chain. There is evidence from satellite tracking that they will move out of the area when great whites are around.

Buoyancy

Bony fish maintain buoyancy by means of air bladders, which sharks and rays don’t have. Their cartilaginous skeletons are less dense than bony ones and sharks have large oily livers which reduce their density. In addition grey nurse sharks can gulp air at the surface and hold it in their stomachs to increase buoyancy

Where they live

The grey nurse sharks were once widely distributed, in the Mediterranean; Atlantic, Indian and western Pacific oceans. They are now facing extinction. They can still be found of North Carolina where they are known as sand tiger sharks and off Natal where they are called ragged-tooth sharks. In Australia they are found off the south west of WA and along the east coast from southern Queensland to southern NSW. The two Australian populations are believed to be genetically separate. Tagging has shown that they may travel over long distances but have their preferred aggregation sites.

The grey nurse sharks can be seen at a number of sites along the NSW and southern Queensland coasts. They are usually found in sandy gutters and rocky caves from about 15 - 40m. At Julian Rocks they have been sighted in all months but the best chance of seeing them is in winter, when the water temperature is below 22°C.
Grey nurse sharks will come quite close to divers, without paying much attention to them; they seem quite aloof, just minding their own business. Sometimes, when they seem disturbed, they will make a snapping sound with their tails, and then rush off. Their palcid nature contributed to their demise.

Grey Nurse sharks - reproduction

Grey nurse shark, male & female

Grey nurse sharks produce only 2 pups at a time. Unusually for sharks they are born headfirst. Shark pups are born able to fend for themselves and the adults show little parental care. Studies on North Atlantic populations have shown that grey nurse sharks initially grow at about 30 cms per year, steadily declining to about 10 cms a year. Males mature at about 1.9m (4-5 years) and females at about 2m (6 years). They grow to a maximum size of 3.2m and an age of about 15 years. Male sharks can be recognised by a pair of claspers (penis like structures) on their undersides behind their pelvic fins. Female sharks have two uteri which share a common opening. In most shark species the males hang on to the females by biting during intercourse. Female sharks often have thicker skins than males. Generally only one clasper at a time is used in intercourse. Male grey nurse sharks in captivity have been seen to show dominance displays. Bites on the tails of young males or around the gills of females and discarded teeth in aggregation

After internal fertilisation, embryos develop in each of the two uteri. They are enclosed in egg cases and have no placental connection to the mother. When the young have consumed their yolk supplies they hatch inside the uteri. The largest embryo in each uterus will eat its brothers and sisters. The mother will continue to produce unfertilised egg on which the young also feed. After 9-12 months 1 pup will emerge from each uterus with a litter every 2 years.

Grey Nurse sharks - an endangered species

Grey nurse shark with gaff

This Grey Nurse, named "Broomstick" was found with a gaff in her mouth, fortunately a vet was able to remove the gaff..

Grey Nurse Sharks are quite large and timid, but they have long narrow teeth which are almost always exposed, so they can look quite fierce.
In the 1950's these docile creatures were ruthlessly slaughtered by people with powerheads, who sought hero status for ridding the oceans of these "savage man-eaters". As a result, Grey nurse shark numbers declined rapidly.
In 1984 they became protected in NSW, and Australia wide in 1997.
The population has not recovered, in part because the grey nurse sharks breed slowly, but also because they continue to be injured by fishing tackle.

Grey nurse shark with fish hook 
Commercial video of rescue       report & photos

Grey Nurse Shark Research

   Submit your photos to help with research

Spot a Shark is a non-profit dive community research project that has been established in conjunction with the Marine Ecology Group at Macquarie University. We will be utilizing a computer based software program to identify individual sharks. Each grey nurse shark has a series of pigmentation spots on either side of their body. These markings are unique to each shark (just as human fingerprints are unique to each one of us). We are therefore asking members of the dive community to send in their photos of GNS to help catalogue the population along the east coast. These photos (if suitable) will then assist our marine biologists to learn more about these endangered creatures.