Grey nurse shark

The grey nurse shark Carcharias taurus is one of Australia’s most iconic and endangered marine species. It is listed as endangered under the Nature Conservation Act 1992, critically endangered (east coast population) under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), and protected under the Fisheries Act 1994.

Grey nurse sharks were hunted to near extinction in the 1960s after being incorrectly labelled as 'man eaters' and targeted by fishers and spear fishers. Recent research estimates approximately 2000 grey nurse sharks live along Australia’s east coast²; however, the breeding population consists of just 400 mature individuals (males and females). ³

The greatest threat to the recovery of the grey nurse shark population along Australia’s east coast is indirect bycatch – either in recreational or commercial line fishing gear, or in shark control equipment. These sharks swallow their prey whole and are instinctively attracted to struggling fish retreating to deeper water after being hooked, often resulting in the sharks being accidentally hooked themselves.

Some fishers may not know they have hooked a critically endangered grey nurse shark, instead mistaking the event for a ‘bite off’. If sharks survive the initial injury or trauma caused by being hooked, many of the swallowed hooks lodge in the stomach and can migrate through the digestive tract, causing internal injuries that may lead to death. Hook ingestion can also result in malnutrition and wasting, which in turn affects the reproductive potential of females and has flow-on effects for the viability of the grey nurse shark population along Australia’s east coast.

Grey nurse sharks are not prolific breeders, producing only one or two pups every two to three years. Because of this slow reproductive rate, their population has been slow to recover from dramatic decline. ⁴

Moreton Bay Marine Park contains three known sites identified as critical for the survival of grey nurse sharks in eastern Australia:

• Cherubs Cave, Moreton Island
• Henderson's Rock, Moreton Island
• Flat Rock, Stradbroke Island.

Fishing prohibitions and diving restrictions were introduced in December 2003 to protect grey nurse sharks at these critical habitats. Given the species’ low birth rate these management measures will become more effective the longer they remain in place.

• Read more about grey nurse sharks.

References and further reading

1. Department of the Environment. (2014). Recovery Plan for the Grey Nurse Shark (Carcharias taurus) 2014. Commonwealth of Australia. https://www.dcceew.gov.au/environment/biodiversity/threatened/recovery-plans/recovery-plan-grey-nurse-shark-carcharias-taurus-2014
2. Bradford, R.W., Thomson, R., Bravingotn, M., Foote, D., Gunasekara, R., Bruce, B.D., Harasti, D., Otway, N. and Feutry, P. (2018). A close-kin mark-recapture estimate the population size and trend of east coast grey nurse shark. Report to the National Environmental Science Program, Marine Biodiversity Hub. CSIRO Oceans & Atmosphere, Hobart, Tasmania.
3. Reid-Anderson, S., Bilgmann, K., and Stow, A. (2019). Effective population size of the critically endangered east Australian grey nurse shark Carcharias taurus. Marine Ecology Progress Series, 610, 137-148.
4. Pollard, D.A., Lincoln Smith, M.P. and Smith, A.K. (1996). The biology and conservation status of the grey nurse shark (Carcharias taurus Rafinesque 1810) in New South Wales, Australia. Aquatic Conserv: Mar. Freshw. Ecosyst., 6: 1-20. https://doi.org/10.1002/(SICI)1099-0755(199603)6:1<1::AID-AQC177>3.0.CO;2-#