Grey Nurse Shark: Facts, Size and Where to Dive

The Grey Nurse Shark: The Gentle Giant of Australia’s Reefs

1. Physical Appearance and Anatomy

Grey Nurse Sharks grow to around 3.2 metres in length, and the heaviest published weight is about 159 kilograms. Their most distinctive features include:

* Long, slender body with a bronze-to-grey dorsal side and pale white belly. * Blunt, conical snout and relatively small eyes. * Multiple rows of long, needle-like teeth that protrude even when the mouth is closed, perfect for gripping slippery fish. * Two dorsal fins of similar size and a large, asymmetrical tail.

Unlike some sharks that must keep swimming continuously to breathe, the Grey Nurse is an *obligate ram ventilator*, meaning it needs to keep moving to pass water over its gills, though it can rest for short periods in high-flow areas where currents do the work.

2. Habitat and Distribution

Grey Nurse Sharks are found in temperate and subtropical waters worldwide, but Australia’s two populations are genetically distinct from those elsewhere, and the east coast population is critically endangered.

In Australia, there are two recognised populations:

* East Coast population, Found mainly between southern Queensland and southern New South Wales. Key aggregation sites include Fish Rock Cave, Julian Rocks, Magic Point, and Shark Gutters at South West Rocks. * West Coast population, Found off Western Australia, from North West Cape near Exmouth around the south-west coast and east to waters south of Cocklebiddy in the Great Australian Bight. Its range is less well known than the east coast’s.

Preferred habitats are rocky reefs, sandy gutters, and deep coastal inshore waters between 15 and 40 metres deep, often close to shore. They’re known to frequent the same aggregation sites year after year, making them vulnerable to human disturbance.

3. Diet and Hunting Behaviour

Despite their fearsome teeth, Grey Nurse Sharks are relatively slow-moving ambush predators. Their diet is made up of:

* Bony fish (such as tailor, trevally, and bonito) * Smaller sharks and rays * Squid and octopus

They hunt mostly at night, often hovering motionless during the day in groups near the seabed. Their hunting style involves quick lunges at passing prey, using those long teeth to snare rather than cut, prey is swallowed whole.

4. Life Cycle and Reproduction: A Case of Intrauterine Cannibalism

One of the most fascinating aspects of Grey Nurse biology is their unusual method of reproduction, known as *adelphophagy* (“eating one’s brother”).

* Females have two uterine chambers. * After internal fertilisation, multiple embryos begin developing in each uterus. * The largest and strongest embryo in each uterus consumes its siblings, leaving just one survivor per side. * The surviving pups continue to feed on unfertilised eggs provided by the mother until birth.

This means a female Grey Nurse produces at most two pups per pregnancy, one from each uterus, after a gestation of about nine to twelve months. Females were long thought to breed every two years, but tracking of east coast females suggests a two-year rest between pregnancies, a three-year cycle that researchers say still needs confirming. Either way, it is one of the slowest reproductive rates of any shark. Pups are born at around 1 metre long and are independent immediately.

5. Behaviour and Social Structure:

Grey Nurse Sharks are often seen in small groups, especially at aggregation sites. These gatherings may be linked to mating or feeding opportunities, but they are generally non-aggressive.

They are known to be curious around divers, sometimes approaching slowly, maintaining eye contact before gliding away. Their slow, deliberate swimming style with mouth open and teeth on display, adds to their fearsome image but is simply their normal way of moving.

6. Threats to the Grey Nurse Shark

The Grey Nurse Shark’s critically endangered status on the east coast is the result of both historical and ongoing threats:

Historical overfishing In the mid-20th century, Grey Nurse Sharks were targeted by game fishers and spearfishers due to their fearsome looks. By the 1980s, populations had crashed. NSW protected the species in 1984 and listed it as threatened in 1999.

Current threats

* Bycatch, Sharks are still accidentally caught on commercial and recreational fishing gear and in shark control nets and drumlines. * Habitat degradation, Coastal development, pollution, and reef damage reduce available habitat. * Low reproductive rate, Even small increases in adult mortality can have large impacts on population recovery. * Disturbance from tourism, While diving with Grey Nurses is popular, poorly managed interactions can stress the animals and disrupt mating or feeding.

7. Conservation and Protection Efforts

Today, Grey Nurse Sharks are protected under both Commonwealth and state legislation. On the east coast, they are listed as Critically Endangered under the Environment Protection and Biodiversity Conservation (EPBC) Act, and the west coast population is listed as Vulnerable. The species is also critically endangered under the NSW Fisheries Management Act 1994, endangered under Queensland’s Nature Conservation Act 1992, and critically endangered on the IUCN Red List.

Conservation measures include:

* Protected aggregation sites with fishing bans or gear restrictions. In NSW, nine sites are declared critical habitat (Bass Point at Shellharbour was delisted after a 2014 review), and in Queensland, Wolf Rock, Flat Rock, Cherubs Cave and Henderson Rock are green zones and designated grey nurse shark areas. * Education campaigns to dispel myths about danger to humans. * Tagging and tracking programs to better understand movements. * Strict penalties for intentional harm or capture.

These efforts appear to be working, slowly. A 2025 CSIRO genetic study estimated that the east coast adult population grew by about 5% a year, from about 1,096 sharks in 2017 to about 1,420 in 2023. The breeding population is still extremely small, and recovery is slow due to their reproductive biology.

8. Grey Nurse Sharks and Human Interaction

Grey Nurse Sharks are one of the safest large sharks to encounter underwater. There are no confirmed fatal attacks in Australia. Divers often report them as calm and tolerant of close observation, provided they are not harassed.

For scuba divers, notable viewing spots include:

* Fish Rock Cave, NSW, Famous for schools of Grey Nurses in winter. * Magic Point, Sydney, Accessible from the city, home to a year-round population. * Bushrangers Bay, Shellharbour NSW, An aquatic reserve south of Sydney where Grey Nurse Sharks patrol the rocky gutters. * Julian Rocks, Byron Bay, Seasonal aggregations, often in photogenic numbers.

Diving etiquette with Grey Nurse Sharks:

* Maintain a respectful distance (3 to 4 metres). * Avoid chasing or cornering them. * Stay low and calm, sudden movements can spook them. * Never touch or attempt to feed them.

In NSW the national Code of Conduct for Diving with Grey Nurse Sharks is backed by law: divers must not night dive at critical habitat sites, touch, feed, chase or harass the sharks, block cave entrances or gutters, dive in groups of more than ten, or use scooters, horns or shark pods. Penalties reach $110,000 and/or two years’ imprisonment. Queensland’s designated grey nurse shark areas have similar rules, including no diving between 6 pm and 6 am.

Here is one of our own encounters with Grey Nurse Sharks at Bushrangers Bay, filmed while keeping a calm, respectful distance:

video

9. Fascinating Facts

* Grey Nurse Sharks can gulp air into their stomachs, giving them neutral buoyancy and allowing them to hover effortlessly. * Their teeth are designed for grip, not cutting, they swallow prey whole. * Despite their size, they are surprisingly shy and will move away if approached too closely. * Juveniles often hang around sheltered inshore reefs before moving to adult aggregation sites. * Their global name variations include *ragged-tooth shark* (South Africa) and *sand tiger shark* (USA).

10. Why Protect the Grey Nurse Shark?

The Grey Nurse Shark plays an important ecological role as a mid-to-high level predator, helping maintain balance in reef ecosystems by controlling populations of mid-sized fish and other marine life.

From a cultural and economic perspective, they are a drawcard for Australia’s dive tourism industry, generating millions of dollars in regional economies. Losing them would not only damage marine biodiversity but also erase a species that has survived virtually unchanged for over 100 million years.

Conclusion

The Grey Nurse Shark is a perfect example of how appearances can deceive. Once feared and hunted, it is now cherished as one of the most iconic marine species in Australian waters. With its slow recovery rate, the survival of the Grey Nurse depends on continued conservation, public awareness, and responsible eco-tourism. By protecting this gentle giant, we help preserve the health of our coastal ecosystems and ensure future generations can share the experience of watching a Grey Nurse glide silently through the blue.

Great Diving Sites to See Grey Nurses - BlueFish Point, Manly, NSW - Bushies - Shell Harbour, NSW

Sources

- NSW DPIRD: Greynurse shark, species page (dpird.nsw.gov.au/fishing/threatened-species/what-current/critically-endangered-species/grey-nurse-shark) - NSW DPIRD: Fishing and diving rules at Greynurse Shark aggregation sites (dpird.nsw.gov.au/fishing/threatened-species/what-current/critically-endangered-species/grey-nurse-shark/new-fishing-and-diving-rules) - NSW DPIRD: Primefact, Greynurse shark (dpird.nsw.gov.au/fishing/threatened-species/what-current/critically-endangered-species/grey-nurse-shark/grey-nurse-shark) - NSW DPIRD: Otway and Louden 2025, Occupation of aggregation sites and migratory movements of the Grey Nurse Shark off eastern Australia, PDF (dpird.nsw.gov.au/__data/assets/pdf_file/0007/1656016/INT25-92017-Otway-and-Louden-2025-Occupation-of-Aggregation-Sites-and-Migratory-Movements-of-GNS_September-20254.pdf) - CSIRO: Slow increase in Australia's eastern grey nurse shark population shows conservation actions are on track - Australian Government: Recovery Plan for the Grey Nurse Shark (Carcharias taurus), 2014, PDF - Australian Museum: Greynurse Shark, Carcharias taurus - FishBase: Carcharias taurus, Sand tiger shark - Wikipedia: Sand tiger shark - Queensland Government: Grey nurse shark-diver interaction research project - South West Rocks Dive Centre: Dive Sites - Sundive Byron Bay: The Dive Site - Michael McFadyen: Bushrangers Bay - YouTube, Tim Barnes: Shark Encounter

Header photo: A grey nurse shark swimming over kelp-covered reef off Cronulla, Sydney, by Bryce Watts-Parker, CC BY 4.0, via Wikimedia Commons.