Grey Nurse Shark Research
The scientific name of the Grey Nurse Shark is Carcharias taurus.
They are also known as the “spotted ragged-tooth shark” or the “sand tiger shark”.
Populations Worldwide
Within Australia, there are two separate populations recognised. One on the East coast of Australia between Northern NSW and Queensland, and the other along the coast of Western Australia.
Worldwide, they are also found in the Indo-West Pacific, Arafura Sea, Western Atlantic, Eastern Atlantic, Northwest Atlantic oceans. See red shaded areas on map below.
Within Australia, there are two separate populations recognised. One on the East coast of Australia between Northern NSW and Queensland, and the other along the coast of Western Australia.
Worldwide, they are also found in the Indo-West Pacific, Arafura Sea, Western Atlantic, Eastern Atlantic, Northwest Atlantic oceans. See red shaded areas on map below.
Conservation Status
In 1984, grey Nurse Sharks were the first shark in the world to become a protected species.
However, in the short space of just 16 years - from 1984 to 2000, the East Coast population has rapidly progressed from the classification of “Protected Species” to ”Critically Endangered”.
The Grey Nurse Shark is currently classified as “Critically Endangered” along the East Coast of Australia and “vulnerable to extinction” along the West Coast, by the Environmental Protection and Biodiversity Conservation Act 1999.
Worldwide they are listed as Vulnerable to extinction by the IUCN.
It is thought that around1000 individuals remain on the East Coast of Australia. In 2009, important sites for Grey Nurse Sharks have been given greater protection status by Marine Parks Authorities.
Distribution and Migration
Grey Nurse Sharks usually inhabit inshore coastal areas, with common environmental elements such as sandy gutters, boulders, caves and rocky reefs.
Their migratory movements are poorly studied, with only limited information on localised population movements. It is suggested that male and female populations on the East coast of Australia are segregated and have separate migratory patterns which may coincide for breeding.
In 1984, grey Nurse Sharks were the first shark in the world to become a protected species.
However, in the short space of just 16 years - from 1984 to 2000, the East Coast population has rapidly progressed from the classification of “Protected Species” to ”Critically Endangered”.
The Grey Nurse Shark is currently classified as “Critically Endangered” along the East Coast of Australia and “vulnerable to extinction” along the West Coast, by the Environmental Protection and Biodiversity Conservation Act 1999.
Worldwide they are listed as Vulnerable to extinction by the IUCN.
It is thought that around1000 individuals remain on the East Coast of Australia. In 2009, important sites for Grey Nurse Sharks have been given greater protection status by Marine Parks Authorities.
Distribution and Migration
Grey Nurse Sharks usually inhabit inshore coastal areas, with common environmental elements such as sandy gutters, boulders, caves and rocky reefs.
Their migratory movements are poorly studied, with only limited information on localised population movements. It is suggested that male and female populations on the East coast of Australia are segregated and have separate migratory patterns which may coincide for breeding.
Tagging
Cattle ear tags were originally used on first and second dorsal fins so that identification could be made by SCUBA divers. These sightings were used to identify migration patterns and population estimates. This system is no longer in use.
Pop-up archival satellite tags are now used to record localised and large scale movements of Grey Nurse Sharks. Data such as water depth and temperature, movement patterns and time spent at sites is stored in the tags memory and after a pre-programmed period, the tag releases from the shark and floats at the surface where the data can be relayed via satellites and sent to NSW DPI scientists.
Acoustic tags transmit signals at specified intervals. These signal are recorded by underwater listening stations. These tags can identify a shark, its depth and surrounding water temperature. There are 60 listening stations along the NSW coast between Queensland and Victoria. This is known as the South East Australian Coastal Acoustic Monitoring System (SEACAMS).
Interesting data collected in tagging studies, reveals that some individual sharks spend around 76% of their time at depths of 40 metres and the remaining time at greater depths of between 69m and even 98m. Within specified monitoring periods - these sharks were found only in waters between 14 and 26 degrees.
Cattle ear tags were originally used on first and second dorsal fins so that identification could be made by SCUBA divers. These sightings were used to identify migration patterns and population estimates. This system is no longer in use.
Pop-up archival satellite tags are now used to record localised and large scale movements of Grey Nurse Sharks. Data such as water depth and temperature, movement patterns and time spent at sites is stored in the tags memory and after a pre-programmed period, the tag releases from the shark and floats at the surface where the data can be relayed via satellites and sent to NSW DPI scientists.
Acoustic tags transmit signals at specified intervals. These signal are recorded by underwater listening stations. These tags can identify a shark, its depth and surrounding water temperature. There are 60 listening stations along the NSW coast between Queensland and Victoria. This is known as the South East Australian Coastal Acoustic Monitoring System (SEACAMS).
Interesting data collected in tagging studies, reveals that some individual sharks spend around 76% of their time at depths of 40 metres and the remaining time at greater depths of between 69m and even 98m. Within specified monitoring periods - these sharks were found only in waters between 14 and 26 degrees.
Feeding
Grey nurse sharks primarily feed upon reef fish including snapper, mulloway, bonito, flathead, wrasse, yellowtail kingfish and occasionally small sharks and squid.
They are harmless to humans, as their dentition is specifically designed with long pointed grasping teeth for capturing and eating small fish.
Biology and Reproduction
It is thought that Grey Nurse can live for up to 25 years - and possibly longer. Their maximum length is 3.20 metres. Having a slow reproductive rate and coastal distribution makes this species vulnerable to human impacts on their mortality.
Male sharks reach sexual maturity at around 2.0m (or 4-6y ears), and females at 2.6m (or 6-8 years).
These sharks are ovoviviparous - meaning young hatch from egg sacs inside the womb and live babies are born. This species also has the unusual phenomena of intra-uterine cannibalism. Females can have multiple embryo’s developing simultaneously, one embryo from each uterus will consume all the other undeveloped embryo’s before they are born.
After a gestation period of 9-12 months, females give birth to two pups around 80-100cm in length. Females only reproduce once every two years.
Source: “Summary of Grey Nurse Shark Scientific Information” NSW Department of Primary Industries and Northern Rivers Catchment Management Authority 2008.
Grey nurse sharks primarily feed upon reef fish including snapper, mulloway, bonito, flathead, wrasse, yellowtail kingfish and occasionally small sharks and squid.
They are harmless to humans, as their dentition is specifically designed with long pointed grasping teeth for capturing and eating small fish.
Biology and Reproduction
It is thought that Grey Nurse can live for up to 25 years - and possibly longer. Their maximum length is 3.20 metres. Having a slow reproductive rate and coastal distribution makes this species vulnerable to human impacts on their mortality.
Male sharks reach sexual maturity at around 2.0m (or 4-6y ears), and females at 2.6m (or 6-8 years).
These sharks are ovoviviparous - meaning young hatch from egg sacs inside the womb and live babies are born. This species also has the unusual phenomena of intra-uterine cannibalism. Females can have multiple embryo’s developing simultaneously, one embryo from each uterus will consume all the other undeveloped embryo’s before they are born.
After a gestation period of 9-12 months, females give birth to two pups around 80-100cm in length. Females only reproduce once every two years.
Source: “Summary of Grey Nurse Shark Scientific Information” NSW Department of Primary Industries and Northern Rivers Catchment Management Authority 2008.
