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CATEGORIES EXPLAINED
by IUCN
( International Union for Conservation of Nature )
EXTINCT
A Shark is Extinct when there is no reasonable doubt that the
last individual has died. A Shark is presumed Extinct when exhaustive
surveys in known and/or expected habitat, at appropriate times (diurnal,
seasonal, annual), throughout its historic range have failed to record
an individual. Surveys should be over a time frame appropriate to the
Shark's life cycle and life form.
EXTINCT IN THE WILD
A Shark is Extinct in the Wild when it is known only to survive in
cultivation, in captivity or as a naturalized population (or
populations) well outside the past range. A Shark is presumed Extinct in
the Wild when exhaustive surveys in known and/or expected habitat, at
appropriate times (diurnal, seasonal, annual), throughout its historic
range have failed to record an individual. Surveys should be over a time
frame appropriate to the Shark's life cycle and life form.
CRITICALLY ENDANGERED
A Shark is Critically Endangered when the best available evidence
indicates that it meets any of the criteria A to E for Critically
Endangered , and it is therefore considered to be facing an extremely
high risk of extinction in the wild.
ENDANGERED
A Shark is Endangered when the best available evidence indicates that it
meets any of the criteria A to E for Endangered (see Section V), and it
is therefore considered to be facing a very high risk of extinction in
the wild.
VULNERABLE
A Shark is Vulnerable when the best available evidence indicates that it
meets any of the criteria A to E for Vulnerable, and it is therefore
considered to be facing a high risk of extinction in the wild.
NEAR THREATENED
A Shark is Near Threatened when it has been evaluated against the
criteria but does not qualify for Critically Endangered, Endangered or
Vulnerable now, but is close to qualifying for or is likely to qualify
for a threatened category in the near future.
LEAST CONCERN
A Shark is Least Concern when it has been evaluated against the criteria
and does not qualify for Critically Endangered, Endangered, Vulnerable
or Near Threatened. Widespread and abundant Sharks are included in this
category.
DATA DEFICIENT ( NO DATA )
A Shark is Data Deficient when there is inadequate information to make a
direct, or indirect, assessment of its risk of extinction based on its
distribution and/or population status. A Shark in this category may be
well studied, and its biology well known, but appropriate data on
abundance and/or distribution are lacking. Data Deficient is therefore
not a category of threat. Listing of Sharks in this category indicates
that more information is required and acknowledges the possibility that
future research will show that threatened classification is appropriate.
It is important to make positive use of whatever data are available. In
many cases great care should be exercised in choosing between DD and a
threatened status. If the range of a Shark is suspected to be relatively
circumscribed, and a considerable period of time has elapsed since the
last record of the Shark, threatened status may well be justified.
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