You already know we love diving with the Grey Nurse Sharks at Broughton Island, but here are a few fun facts about these impressive animals that you may not have heard before.
#1: Grey Nurse Sharks (Carcharias taurus) are found inhabiting continental shelves all over the world, although depending on the area they may also be known as Sand Tiger Sharks, Spotted Ragged-Tooth Sharks, or Blue-Nurse Sand Tigers.
#2: They are not related to Tiger Sharks, but are the cousins of Great White Sharks. Having said that, Grey Nurse Sharks are one of the most docile species of sharks and are not a threat to swimmers or divers unless provoked.
Photo courtesy Malcolm Nobbs.
#3: Grey Nurse Sharks are nocturnal feeders and the only shark species known to swallow air at the surface and store it in their stomach. This allows them to maintain near-neutral buoyancy, which helps them to hunt motionlessly and quietly. Their diet consists mostly of fish, smaller sharks and rays with the occasional squid or crustacean for added flavour.
#4: Small scars are often seen on female Grey Nurse Sharks in autumn because the males sharks bite them during the mating process. This is perhaps less unusual than what happens during pregnancy, as the most developed embryo will feed on its lesser-developed siblings in a reproductive strategy known as intrauterine cannibalism, or more colourfully, adelphophagy, which literally means eating one’s brother.
#5: Grey Nurse Sharks have the lowest reproductive rate of any shark. They tend to breed once every two years and only have two pups per litter.
#6: In 1984, Grey Nurse Sharks became the first protected shark species in the world thanks to legislation passed by the New South Wales government. The east coast population that we dive with is currently listed as critically endangered. Their main threats are illegal fishing and accidental capture.
#7: You can help contribute to conservation efforts by removing any rubbish or fishing gear that you see in the water or on the beach, or by assisting New South Wales Fisheries with surveys of the sharks and their habitats.