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Protecting the grey nurse shark
Information paper
On this page:
- Introduction
- The current situation
- Immediate concerns
- Protecting critical habitat
- What you can do to help
- Contacts
Introduction
The grey nurse shark is one of Australia's most endangered marine species. Despite not being a threat to people, it was hunted almost to extinction during the 1960s due to its fierce appearance. Today, the remaining sharks are under threat from fishing, diving and other human activities. It is estimated that there are fewer than 500 left along Australia's east coast. As a top level predator it is possible the shark plays an important role in ocean ecology.
Grey nurse shark aggregation sites have been found at least four sites in Queensland, all of which are in the south-east. The sharks are listed as endangered under the State's Nature Conservation Act 1992, which is the highest threatened category, and are also listed as critically endangered by the Federal Government. In 1984, the grey nurse became the first shark in the world to be protected and they are now protected at four sites in Queensland waters (see section on protecting critical habitat).
The Queensland Government is concerned about the increasing pressure on this small population. Recent research has indicated that on current trends, the grey nurse shark could be extinct within 40 years.
The current situation
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Scientists are only beginning to learn about the unique biology and ecology of grey nurse sharks. A lack of knowledge led the sharks to be labelled "man-eaters". They were often mistaken for other sharks that posed a threat to people and were wrongly blamed for attacks. Unfortunately, this resulted in the deliberate slaughter of large numbers of grey nurse sharks.
In truth, the grey nurse shark is a passive species, and is not considered dangerous to humans. Their teeth are designed to catch small prey such as squid, fish and crustaceans. It is possible that its feeding technique - "nursing" or rounding up small fish into a tight school - is where it gets its common name. Its gentle nature makes it a popular shark for display in commercial aquaria, where visitors can sometimes enjoy the experience of swimming with the sharks.
Once found around the world, the grey nurse shark is now restricted to waters off parts of the USA, Uruguay, Argentina, South Africa and Australia. South-east Queensland and New South Wales are home to one of Australia's two populations. The second is off Western Australia. In Queensland, the sharks are usually found from Wolf Rock off Double Island Point to the Queensland/NSW border.
The east coast population is under serious threat. The sharks are at risk from recreational and commercial fishers' incidental capture, illegal shark finning, scuba diving and other human activities. Fishing hooks are one of the main causes of death as they become embedded in the sharks and can cause serious infection. Sharks can also starve as the hooks may disrupt their feeding and digestion.
There is evidence that the number of sharks with hooks in their flesh has increased. Results from a NSW Government research program indicate that the incidence of "hooked" sharks has jumped from two percent to 12 percent in the past decade. Autopsies on 10 grey nurse sharks in NSW waters found six had swallowed hooks, indicating there is more damage to the population than can be seen.
Divers could have a negative impact on the sharks by approaching them too closely or diving with large groups of divers which could disrupt their breeding or feeding behaviours.
Immediate concerns
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A considerable number of juvenile and heavily pregnant females have been seen at Wolf Rock, Flat Rock and Henderson Rock and are thought to pup from August to October. Surveys at Wolf Rock since January 2003 have shown four out of 15 mature sharks sighted had tackle embedded in their bodies. In July, two out of 12 sharks at Flat Rock were also found with fishing tackle. It is unclear how many at other sites are currently hooked, particularly as many hooks are ingested in the shark's stomach. The major concern is the effect that the high incidence of tackle damage is having on the current breeding population. With such a small population on the east coast, the death of even a handful of individual sharks can have a detrimental effect on the entire species.
Protecting critical habitat
Grey nurse sharks are mostly nocturnal feeders. They spend the daylight hours swimming in gutters around the rocks at their aggregation sites. They prey on pilchards, jewfish, tailor, bonito, morays, blue groper, sea mullet, flatheads, yellowtail kingfish, small sharks, squid and crustaceans.
Recent acoustic tracking studies by CSIRO and the Queensland Parks and Wildlife Service have found the Queensland grey nurse sharks move some distance at night from their aggregation sites. At Flat Rock in the Moreton Bay Marine Park, two tagged grey nurse sharks were recorded travelling up to 1200m away to feed at night. There are four Grey Nurse Shark Protection Areas in Queensland that were declared on 19 December 2003. These are within a 1.2 kilometre radius of the following sites:
- Wolf Rock (off Double Island Point in the proposed Great Sandy Marine Park, Northern Section);
- Flat Rock (off North Stradbroke Island, Moreton Bay Marine Park);
- Cherub's Cave (Moreton Bay Marine Park); and
- Henderson Rock (Moreton Bay Marine Park).
Wolf Rock is the most important grey nurse shark area in Queensland. It is a mating site and has a high number of female and pregnant sharks. Grey nurse sharks are slow breeders, producing one or two pups every two years. This slow breeding rate hampers the population's recovery from low numbers.
Various fishing activities are prohibited within these aggregation sites which can be viewed at the Grey Nurse Shark Protection Areas web page. There are also various diving restrictions under the Environmental Protection Agency's (EPA) Marine Parks and Nature Conservation legislation which can be found on the EPA's website: www.epa.qld.gov.au
NSW controls fishing and diving activities in its 10 grey nurse shark sites, although these regulations are under review due to recent grey nurse population estimates and concerns over incidental hooking.
What you can do to help
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If you catch or find a dead grey nurse shark, please retain the body and immediately contact the Queensland Parks and Wildlife Service duty ranger on pager number 3836 3586, or the Queensland marine stranding hotline on 1300 360 898.
If you catch a live grey nurse shark, return it to the water as soon as possible. If possible, take photos of caught sharks, regardless of photo quality, to assist in studies on monitoring the grey nurse shark population and migration along the east coast.
If you catch a grey nurse shark, record the fisher's or diver's name, address and phone number; site name; time and date; depth of capture; tackle and bait used; GPS coordinates; and water temperature (if known). Also record the shark's gender; size; tag colour and number; and other special observations. Return this information to the Environmental Protection Agency as soon as possible. The address is listed below. You also have obligations to report the capture to Environment Australia (see the website www.ea.gov.au ).
Contacts
Threatened Species and Ecosystems Unit
Environmental Protection Agency
PO Box 155
Brisbane Albert Street Qld 4002
Phone: +61 7 3225 1295
Fax: +61 7 3327 6386
Email: greynurseshark@epa.qld.gov.au
Crab and Estuarine Unit
Fisheries
Department of Primary Industries and Fisheries
GPO Box 46
Brisbane Qld 4001
Ph: DPI&F Call Centre 13 25 23
Fax: +61 7 3225 1823
Email: greynursesharks@dpi.qld.gov.au
Last updated 20 May 2004
