Grey Nurse Shark - Carcharias
taurus
Family: Odontaspididae
Additional Grey Nurse Shark Images
The
Grey Nurse Shark (Carcharias taurus) is one of the most endangered species
in Australian waters. Two separate populations exist in Australian waters, a
west coast population that is listed as 'vulnerable' and the east coast population
that is listed as 'critically endangered'. The range of the east coast population
is believed to extend from Wolf Rock in Queensland down to Montague Island in
NSW. Research by scientists has found that there are less than 500 individuals
remaining on the east coast of Australia. The species is also found in several
other locations around the world. It is known as the Ragged Tooth Shark in Africa
and the Sand Tiger Shark in the United States. The species is protected in the
United States however in South Africa there is a recreational bag limit of 5
per person per day!
One
of the major contributing factors to the species decline is its unusual reproductive
biology. Grey nurses reach sexual maturity at 4-6 years for males and 6-8 years
for females. They are an ovoviviparous species, meaning that they give birth
to pups after they have hatched from eggs within the uterus. This is where the
reproductive system gets interesting. Up to 15 embryos start developing in each
of the two uteri and the two most advanced embryos in each uterus then eat all
the other developing embryos and unfertilised eggs. This phenomenon is known
as inter-uterine cannibalism. So they have basically eaten all their brothers
and sisters before they are born!
The
gestation period is also very long, lasting 9-12 months and the two pups are
born at about 80cm to 100cm in length. Females only reproduce every 2nd year,
therefore on average only 1 pup per female is produced per year.
The maximum size for the species is believed to
be about 3.5 metres and it estimated they grow up to 25 years old in the wild.
They are considered a harmless shark and are not a threat to humans unless they
are provoked.
Research
on the grey nurse sharks in Australia has found that they migrate north - south
at certain times of the year. It is believed that their migration is in relation
to changing water temperatures, as they are generally found in water temps from
18 - 24 degrees Celsius, and that they are also following prey species such
as the jewfish and mullet.
As
an endangered species, it is illegal for any person to target or keep grey nurse
sharks in Australia. Penalties up to $220,000 and/or two years in jail apply
to any person found harming the species in NSW and Qld. There are now management
arrangements in place in NSW and QLD to protect critical habitat sites where
grey nurse sharks aggregate to mate, pup and feed. Hopefully the protection
of these sites will lead to a recovery in the east coast population of grey
nurse sharks.
Additional Grey Nurse Shark Images
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The
Grey Nurse Shark (Carcharias taurus) is one of the most endangered species
in Australian waters. Two separate populations exist in Australian waters, a
west coast population that is listed as 'vulnerable' and the east coast population
that is listed as 'critically endangered'. The range of the east coast population
is believed to extend from Wolf Rock in Queensland down to Montague Island in
NSW. Research by scientists has found that there are less than 500 individuals
remaining on the east coast of Australia. The species is also found in several
other locations around the world. It is known as the Ragged Tooth Shark in Africa
and the Sand Tiger Shark in the United States. The species is protected in the
United States however in South Africa there is a recreational bag limit of 5
per person per day!
