Species: Carcharias taurus

Bundjalung name: Buwayi, buwi

Status : Vulnerable (IUCN), Critically Endangered (NSW) – the total east coast population is thought to be around 1200 individuals

Characteristics

• Size: Adult: 3.6m, 230kg; Newborn: 1m, 7-10kg

• Appearance: Grey to greyish-brown in colur with a pale belly and freckled spots found on the rear of their body. These sharks have a large, stout body and pointed snout with two large dorsal fins of similar size. They’re sometimes known as the spotted ragged-toothed shark due to their long, protruding teeth. Despite their sharp toothy grin, these sharks are harmless to humans. 

• Breeding/Reproduction: Males and female sharks both mature at approximately 2.2 meters in length. Their reproduction strategy is through sexual reproduction and are ovoviviparous meaning usually two pups are born per litter once every two years. The eggs remain inside the stomach and develop into embryos. Eventually the largest and most advanced embryo consumes the smaller individual. Gestation lasts from 9-12 months and size at birth is 1 meter.

• Diet: Diet ranges from teleost fish species, smaller sharks, rays, squids and lobsters all depending upon their surrounding habitat. 

Habitat: Grey Nurse Sharks are found in temperate coastal waters around the world, usually between 15 and 40 metres depth near sandy gutters or rocky caves and reefs. Found in medium-sized aggregations ranging from 20-80 individuals, these sharks are often observed as though they are hovering motionless just above the sea bed,deep sandy bottom gutters, rocks inshore reef systems and islands. Residing in coastal environments, in surf zones and down to depths of around 25 meters. 

The east coast of Australia is home to a small and threatened population of these sharks, which migrate primarily along the coast of NSW and southern QLD and aggregate at several key sites. Nguthungulli / Julian Rocks is a critical habitat site for these sharks, and during the winter months they can often be seen hanging out here. 

Threats: Historically grey nurse were targeted by fishers as well – thought to be a “killer shark” they were actively hunted in the late 20th century. Many populations are still under very serious threat largely due to ongoing human impacts primarily from over-fishing of their species. Once fished throughout their whole habitat distribution, grey nurse shark species are still consumed in countries like Japan and for the shark fin trade in China. Since 1984, when this species was the first shark in the world to be protected by an act of parliament, they have been protected from fisheries around Australia. Within Australian waters they are now a protected species however the shark nets in NSW and QLD pose a direct threat. Additionally overfishing of their prey species and to accidental catches still pose threats. Many indirect threats are impacting grey nurse such as climate change, habitat degradation, reduction of food and unsustainable tourism practices. 

 Along with their reproductive biology (late sexual maturity and having a maximum of 2 pups every 2 years) and habitat loss, their survival continues to be threatened and population recovery is slow. 

Characteristics

• Length/size: With a wingspan (disc width) of up to 5 metres, they’re one of the largest rays in the world. They can weigh up to 700 kg.

• Colour: Usually grey/black on their back with lighter grey/white patches, and white on the belly often with grey/black spots. These dark spots can be used to identify individual manta rays, like a fingerprint. Some rays are melanistic (mostly black) and occasionally leucistic (mostly white) and there’s even one record of a pink manta!

• Breeding/reproduction: All mobulid rays reproduce via aplacental viviparity, meaning they give birth to live young that are hatched from an egg inside the female’s uterus. The pup, which is wrapped in a thin membranous egg case, hatches inside the mother’s oviduct and then feeds on the mother’s uterine milk until it is fully developed and ready to be born. Gestation is estimated to be 12 or 13 months and pups are around 1.2 – 1.5 metres wide when born. The young come out with their wings wrapped around them like a burrito. 

• Diet: They are observed filter-feeding on zooplankton (copepods, shrimp, crab larvae) in surface waters, but it is believed they gain much of their energetic requirements when foraging on zooplankton at depth. The cephalic lobes (or ‘head fins’ located either side of their mouth) can be rolled up for streamlined travel, then unfurled to form a funnel-like shape around their mouth when feeding. 

Habitat: Preferring warmer waters, these rays are found throughout the tropical Indo-Pacific, mainly in coastal waters. 

Threats: Overfishing is the biggest threat, as slow reproducers it’s easy for local populations to become depleted. There are targeted fisheries in many countries for their meat and products such as the gill plates (used in Traditional Chinese Medicine). Locally, entanglement is an issue (such as in shark nets or fishing waste). Climate change and microplastics (which can be filtered along with their food) are also likely to have negative impacts. 

Local research: These charismatic rays visit the Byron Bay Hope Spot in the warmer months (between September and May) when they’re often spotted attending cleaning stations at Nguthungulli / Julian Rocks. Over 150 individuals have been identified off Byron Bay by Project Manta using photo-ID, and there have been approximately 300 confirmed sightings of these individuals within the Cape Byron Marine Park. Some of the identified manta rays have been recorded moving north to the Great Barrier Reef, and south to the Solitary Island Marine park, demonstrating that they are part of a much bigger population along Australia’s east coast.