Transcript Presentation Template

458
Estimating Extinction Risk
(the IUCN criteria)
Fish 458; Lecture 24
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Identifying Species at Risk of
Extinction – The IUCN Framework
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The IUCN Red List characterizes all
species (plants and animals) into
various categories of risk of extinction.
The same framework is applied to all
organisms irrespective of their biology
and exploitation history (implies a need
to scale biological quantities – e.g. by
generation time).
Goals for IUCN Listing
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Provide scientifically-based information on the
status of species at the global level.
Draw attention to the magnitude and
importance of threatened biodiversity.
Influence national and international policy
and decision makers.
Provide information to guide actions to
conserve biological diversity.
Summary Statistics
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Threatened Species (of those evaluated*)
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Total (41%: 3155+723 of 9474)
Mammalia (57%: 1130+87 of 2133)
Aves (56%: 1183 +3 of 2123)’
Elasmobranchii (41%: 39+0 of 95)
Number of threatened species by country
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USA (998; 131 fishes)
Australia (524; 44 fishes)
A History of the Listing Process
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Qualitative until 1994.
1994 = First quantitative framework
(used for the 1996 Red List).
2000 = Revision to the 1994
framework.
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Basic framework (2000 model)
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The threatened categories
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Critically Endangered (“considered to be
facing an extremely high risk of
extinction in the wild”).
Endangered (“considered to be facing a
very high risk of extinction in the wild”).
Vulnerable (“considered to be facing a
high risk of extinction in the wild”).
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The criteria
A.
B.
C.
D.
E.
Reduction in population size
Small geographic range
Small population size and declining
Very small population size
Quantitative estimate of extinction risk
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The basic structure
Criteria
CR
EN
VU
A
Value
Value
Value
B
Value
Value
Value
C
Value
Value
Value
D
Value
Value
Value
E
Value
Value
Value
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How to use the system
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Rank the species against each of the criteria
(note that there are separate thresholds for
each criterion / category of risk).
Set the final category to the highest level of
risk.
This process has been computerized
(RAMAS).
The A criterion
(mature individuals)
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Direct observation.
An index of abundance.
Decline in the area of occupancy, extent
of occurrence / quality of habitat.
Actual or potential levels of exploitation
Effects of introduced taxa, pollutants,
etc.
The A Criterion
(past reductions)
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“Observed, estimated, inferred or
suspected” reduction over 10 years or
three generations of
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[90%, 70%,50%] and causes ceased,
understood and reversible;
[80%, 50%, 30%] and causes not ceased,
not understood, or may not be reversible
The A criterion
(future reductions)
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Projected reduction over any 10 year or
three generation period of [80%, 50%,
30%].
Can include the past and future.
Reduction may not have ceased, not be
understood, or may not be reversible.
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Defining Space in the System
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Extent of occurrence: “area contained
within the shortest continuous boundary
which encompasses the present
occurrence of a taxon”.
Extent of occupancy: “smallest area
essential at any stage to the survival of
the population” (e.g. breeding area).
Criterion B
(Geographic range)
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Extent of occurrence less than [100km²,
5000km², 20000km²] and two of:
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Severely fragmented or at a single location (CR) /
no more than 5 locations (EN) / no more than 10
locations (VU);
Continuing decline;
Extreme fluctuations
Extent of occupancy less than [10km²,
500km², 2000km²] and two sub-criteria.
Criterion C
(Small size and declining)
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Population size less than [250,5000,10000]
and either:
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Continuing decline at least [25% within three years or
one generation, 20% within five years or two generations,
10% within 10 years or three generations]
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Continuing decline and
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No subpopulation larger than [50, 250, 1000] individuals;
At least [90%, 95%, 100%] of individuals in one
subpopulation;
Extreme fluctuations.
Criterion D
(Very small population size)
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Critically endangered: 50 mature
individuals.
Endangered: 250 mature individuals.
Vulnerable: 1000 mature individuals OR
very restricted area of occupancy
(<20km²) or number of locations (5 or
less).
Criterion E
(Quantitative analysis)
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Probability of extinction in the wild is at
least
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50% within 10 years or three generations
(CR).
20% within 20 years or five generations
(EN).
10% within 100 years (VU).
Overview of Success
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Very widely used internationally.
Does not require much data.
Generally easy to understand and apply.
Can be applied across a wide range of
taxa (e.g. insects to trees).
Problems with the Framework-I
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Specifying thresholds
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The thresholds are only “roughly” comparable.
The original intent was for the thresholds to be
consistent with the E criterion but this has
changed over time.
The thresholds for the A criterion in particular
(and the use of “inferred” / “suspected” declines)
have been controversial (e.g. listing of Atlantic
cod).
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Problems with the Framework-II
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Fishes!
1996 Red List “The quantitative criterion (A1abd) for
the threatened categories may not be appropriate for
assessing the risk of extinction for some species,
particularly those with high reproductive potential,
fast growth and broad geographic ranges. Many of
these species have high potential for population
maintenance under high levels of mortality, and such
species might form the basis for fisheries…”
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Problems with the Framework-III
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The decline criterion.
“Managed” species.
“Long-lived” species (three generations can
be several thousand years for some trees).
Should criteria E over-rule?
The criteria are “broad brush” and should not
“overrule” more sophisticated analyses. Many
fish species would have being threatened or
endangered at some time.
How to incorporate “precaution”.
No use of “ecological knowledge”.
Areas of Disagreement
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African elephants;
Some fish species (cod);
Marine turtles (Flatback, Olive Ridley,
Green);
Crocodiles.
[Note all are species subject to harvest.]
Readings
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IUCN Web site: www.iucn.org
Mace and Lande (1991): Conservation
Biology 5:148-157.
Mace et al. (1992) Species 19:16-22.
Mace and Stuart (1994) Species 22: 1324