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THE CONSERVATION STATUS OF MARINE
BIODIVERSITY OF THE WESTERN INDIAN
OCEAN
The IUCN Red List of Threatened SpeciesTM - Regional Assessment
R. Bullock, G. Ralph, E. Stump, F. Al Abdali, J. Al Asfoor, B. Al Buwaiqi, A. Al Kindi, A. Ambuali,
T. Birge, P. Borsa, F. Di Dario, B. Everett, S. Fennessy, C. Fonseca, C. Gorman, A. Govender,
H. Ho, W. Holleman, N. Jiddawi, M. Khan, H. Larson, C. Linardich, P. Matiku, K. Matsuura,
C. Maunde, H. Motomura, T. Munroe, R. Nair, C. Obota, B. Polidoro, B. Russell, S. Shaheen,
Y. Sithole, W. Smith-Vaniz, F. Uiblein, S. Weerts, A. Williams, S. Yahya, K. Carpenter
INDIAN OCEAN
WESTERN
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THE IUCN RED LIST OF THREATENED SPECIES™ – REGIONAL ASSESSMENT
THE CONSERVATION STATUS OF MARINE
BIODIVERSITY OF THE WESTERN INDIAN
OCEAN
R. Bullock, G. Ralph, E. Stump, F. Al Abdali, J. Al Asfoor, B. Al Buwaiqi, A. Al Kindi, A. Ambuali,
T. Birge, P. Borsa, F. Di Dario, B. Everett, S. Fennessy, C. Fonseca, C. Gorman, A. Govender,
H. Ho, W. Holleman, N. Jiddawi, M. Khan, H. Larson, C. Linardich, P. Matiku, K. Matsuura,
C. Maunde, H. Motomura, T. Munroe, R. Nair, C. Obota, B. Polidoro, B. Russell, S. Shaheen,
Y. Sithole, W. Smith-Vaniz, F. Uiblein, S. Weerts, A. Williams, S. Yahya, K. Carpenter
The designation of geographical entities in this book, and the presentation of the material, do not imply the
expression of any opinion whatsoever on the part of IUCN or other participating organisations concerning the
legal status of any country, territory or area, or of its authorities, or concerning the delimination of its frontiers or
boundaries.
organisiations.
IUCN is pleased to acknowledge the support of its Framework Partners who provide core funding: Ministry
Published by: IUCN, Gland, Switzerland
Copyright: © 2021 IUCN, International Union for Conservation of Nature and Natural Resources
Reproduction of this publication for educational or other non-commerical purposes is
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Reproduction of this publication for resale or other commercial purposes is prohibited
without prior written permission from the copyright holder.
Linardich, C., Matiku, P., Matsuura, K., Maunde, C., Motomura, H., Munroe, T., Nair, R.,
Obota, C., Polidoro, B., Russell, B., Shaheen, S., Sithole, Y., Smith-Vaniz, W., Uiblein, F.,
Weerts, S., Williams, A., Yahya, S., Carpenter, K. (2021). The conservation status of marine
biodiversity of the Western Indian Ocean. Gland, Switzerland: IUCN. vii + 32 pp.
ISBN: 978-2-8317-2098-2 (PDF)
Cover photos: Front - Coral Reef, Zanzibar © F. Di Dario.
Chaetodon melapterus by D.P.
Wilson and licensed under CC BY 2.0
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Commons Attribution 2.0 are the work of D.P. Wilson and should not be reproduced without proper attribution. Note
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Table of Contents
Acknowledgements ............................................................................................................................................iv
Executive summary .............................................................................................................................................v
Commonly used acronyms...............................................................................................................................vii
1. Background
1.1 The Western Indian Ocean region ................................................................................................. 1
1.2 Biodiversity and endemism ............................................................................................................2
1.3 Threats to marine biodiversity ....................................................................................................... 3
1.4 Assessment of extinction risk: IUCN Red List of Threatened SpeciesTM ....................................... 3
1.5 Project objectives ..........................................................................................................................4
2. Methods
2.1 Geographic scope .........................................................................................................................6
2.2 Taxonomic scope ........................................................................................................................... 6
2.3 Preliminary assessments and pre-workshop data collection ......................................................... 7
2.4 Red List assessment workshops ................................................................................................... 7
2.5 Post-workshop review ...................................................................................................................7
2.6 Methodology for spatial analyses .................................................................................................. 8
3. Results and discussion
3.1 Conservation status of marine biodiversity .................................................................................... 9
3.2 Trends by taxonomic group ......................................................................................................... 10
3.3 Spatial distribution of species ...................................................................................................... 12
3.4 Threats ........................................................................................................................................ 15
3.5 Research needs ..........................................................................................................................17
.......................................................................................................... 18
3.7 Species conservation successes .................................................................................................19
4. Conclusions
4.1 Overview ..................................................................................................................................... .20
4.2 Application of project results ........................................................................................................21
4.3 General conservation strategies and tools .................................................................................. 22
4.4 Next steps ....................................................................................................................................23
References ........................................................................................................................................................ 25
Appendix: Expert participants ........................................................................................................................ 31
iii
Acknowledgements
This project represents a major expansion of the
IUCN Red List process in the Western Indian
Ocean and could not have been completed
without numerous donors and hundreds of
experts. The most recent assessments were
completed with the generous support of the
Total Foundation and Toyota Motor Corporation.
We thank The Deep and Oceanario de Lisboa
for their support of marine IUCN Red Listing
partnerships, which have contributed greatly to
the assessments in this report.
IUCN’s Red Listing process relies on the
willingness of scientists to contribute and
pool their collective knowledge on species, in
order to make the most reliable and up-to-date
assessments. Without such commitment, this kind
of regional overview would not be possible. We
would therefore like to acknowledge and thank all
of the people who gave their time and valuable
expertise during the assessments. Thanks to
their guidance and support of the Global Marine
Species Assessment initiative of IUCN’s Global
Species Programme Marine Biodiversity Unit
since its inception.
We extend our gratitude to the Oceanographic
Research Institute of the South African
Association for Marine Biological Research,
especially Dr. Larry Oellermann and Ramini
Naidoo, for hosting the third Red List workshop
and providing logistical assistance. We also thank
hospitality during the second Red List workshop.
peer-reviewers for their helpful comments that
improved this report.
iv
Spotted Sharpnose (Canthigaster solandri
CC BY 2.0
Executive summary
The Western Indian Ocean (WIO) is comprised of
productive and highly diverse marine ecosystems
that are rich sources of food security, livelihoods,
and natural wonder. The ecological services
that species provide are vital to the productivity
of these ecosystems and healthy biodiversity is
essential for the continued support of economies
and local users. The stability of these valuable
resources, however, is being eroded by growing
threats to marine life from overexploitation,
habitat degradation and climate change, all of
which are causing serious reductions in marine
ecosystem services and the ability of these
ecosystems to support human communities.
understanding the conservation status of the
region’s marine biodiversity is a critical step in
applying informed management and conservation
measures to mitigate loss and retain the
ecological value of these systems.
The International Union for Conservation of
Nature (IUCN) Red List Categories and Criteria
are the most widely used and objective system
of quantifying the conservation status of species.
For this report, Red List assessments for marine
with existing assessments for other marine
species groups to generate a comprehensive
assessment of the conservation status of the
marine biodiversity of the WIO. The species
assessed for this report were done so through
clade-based and regionally focused Red List
assessment workshops involving hundreds of
taxonomic experts from around the world. To
region, three workshops were held in Tanzania,
Oman and South Africa over the course of three
experts from 14 countries participated in the three
workshops.
Among the more than 4,000 species
assessments compiled for this report, 473
Threatened with extinction at the global level,
according to the IUCN Red List Categories and
Criteria. Incorporating uncertainty in the true
of all species were estimated as being currently
all assessed species being threatened. Spatial
analyses of species richness across the region
the southern Red Sea and the southern coast
of India. Major threats were analysed amongst
threatened and Near Threatened species, of
by biological resource use, largely in the form of
population decline for all threatened and Near
and sea turtles. The 237 threatened and Near
Threatened reef-building corals are impacted
habitat degradation and destruction through
pollution, coastal development and other habitat
assessed species groups. From these analyses,
this report highlights trends in research needs
for species in the region, including priorities for
fundamental biological and ecological research
and quantifying trends in the populations of
species.
v
species, the conservation status of the Western
Indian Ocean region is moderately high, relative
to the status of the same taxonomic suite
of species assessed in other regions. This
comparatively high level of threatened biodiversity
highlights the importance of timely and targeted
conservation actions for the biodiversity of
the region moving forward. The region has
the highest levels of uncertainty in species
other tropical regions. The analyses presented
here also highlight particularly threatened and
susceptible taxonomic groups, geographical
hotpots of conservation priority as well as trends
in major anthropogenic threats. The assessments
and analyses submitted in this report should
inform conservation decision-making processes
and will be valuable to policymakers, natural
resource managers, environmental planners and
NGOs.
vi
Starry Moray (Gymnothorax nudivomer
BY 2.0
Commonly used acronyms
Red List Categories
VU Vulnerable
NT Near Threatened
LC Least Concern
International Organizations
IUCN International Union for
Conservation of Nature
SSC Species Survival Commission
SSG Species Specialist Group
RLA Red List Authority
MBU Marine Biodiversity Unit
FAO Food and Agriculture Organization
of the United Nations
Country Codes
BHR Bahrain
IOT British Indian Ocean Territory
(Chagos Archipelago)
COM Comoro Islands
ATF French Southern and Antarctic
Lands (Bassas da India, Glorioso
IND India
IRN Iran
ISR Israel
KWT Kuwait
MDG Madagascar
MDV Maldives
MUS Mauritius
MYT Mayotte
MOZ Mozambique
OMN Oman
PAK Pakistan
SAU Saudi Arabia
SYC Seychelles
SOM Somalia
ZAF South Africa
LKA Sri Lanka
SDN Sudan
TZA Tanzania
vii
1.1 The Western Indian Ocean region
diverse marine ecological system on the planet.
On its western periphery, covering approximately
30 million km² and spanning the waters of
32 countries and territories, lies the Western
northeastern range experiences heavy monsoon
rains while the northwestern range is bordered
by arid land and is characterized by large semi-
enclosed bodies of water such as the Red Sea.
Shallow coral reef, estuaries, seagrass and
mangrove systems are all found in coastal areas.
The contrasting habitats within the region may
is likely to be higher where unique habitats occur
(Kier et al., 2009). Unfortunately, due to multiple
factors, this region is understudied and has much
to be discovered (Wafar et al., 2011).
The highly diverse marine biodiversity of the
WIO has been a rich source of food security,
livelihoods and natural wonder for the peoples
WIOMSA, 2015). The ecological services that
species provide are vital to the existence of these
marine ecosystems (Palumbi et al., 2009) and a
healthy biodiversity is essential for maintaining
a safe operating space for humanity (Rockstrom
et al., 2009). Unfortunately, growing threats
to marine life from overexploitation, habitat
degradation and climate change are seriously
impacting marine ecosystems globally (Halpern
reductions in marine ecosystem services and
the ability of the ecosystem to support human
communities (Worm et al., 2006).
Some of the most heavily impacted marine biotas
in the world are in the Western Indian Ocean
where drastic reductions in coral cover occurred
because of sustained heightened sea surface
temperatures and subsequent widespread
bleaching events in the late 1990s (Wilkinson et
al., 1999). Human population growth in the region
also poses substantial threats to the sustainability
of coastal biota: many of the countries in the
Western Indian Ocean are characterized by high
population growth rates, high population density,
1
1. Background
Figure 1: The boundaries of the Western Indian
and Bianchi (1984).
1.2 Biodiversity and endemism
The WIO is associated with areas of high species
richness and high endemism. It is ranked as one
of the world’s richest oceanic regions (Keesing
species known from the Western Indian Ocean
Across taxa, high levels of endemism have been
recorded in in the territorial waters of South
Africa, the Red Sea, India, Mauritius, La Reunion,
the Seychelles, India and the Maldives (Van der
DiBattista et al., 2016).
The productivity of the rich ecosystems of the
WIO has so far supported economies and
livelihoods in the region (Samoilys et al., 2015).
Fisheries form a large economic sector in most
nations, providing food security and employment
in coastal communities, and contributing to
national economies and GDPs (Carpenter et
WIOMSA, 2015). Fisheries in the Western Indian
Ocean region range from dynamic artisanal
of gears used in near-shore environments, to
pelagic long-lining and purse-seining (Cochrane
WIOMSA ,2015).
The biodiversity of the region supports a growing
has grown rapidly in recent years, and in some
Gossling, 2006). Tourists are drawn to the
region’s beaches, lagoons, coral reefs, wildlife,
and coastal cultural sites (Gossling, 2006).
Biodiversity also provides important aesthetic,
cultural and spiritual services to coastal
communities.
Knowledge of marine biodiversity in the
greatly from both internationally and locally
(1959 to 1965) that supported participants from
20 countries, considerably enhanced knowledge
of marine biodiversity beyond shallow and easily
accessible waters. However, current marine
across the region, varying according to the
the marine realm of the WIO remain (Wafar et al.,
2
Outside Malindi Fish Market, Zanzibar © G.
Saluta.
1.3 Threats to marine biodiversity
Historically low levels of economic development
in parts of the WIO have meant that, in some
areas, the marine ecosystem may have been less
impacted by coastal human activity. For example,
arid nations such as Somalia and Sudan have
low coastal populations densities due to lack of
freshwater and high temperatures, thus limiting
development and exploitation in the coastal
However, contemporary increases in growth
and development across the region are likely to
increasingly impact marine biodiversity. Previous
regional-scale work has highlighted “hotspots”
areas where high endemism combines with
multiple threats including coastal and industrial
development, global warming, pollution, and
portions of their mangrove shoreline, coral reefs
have declined due to major bleaching events
and overexploitation of pelagic and demersal
reported across vast areas of the WIO including
but not limited to the Arabian Gulf, Sri Lanka
to a loss of ecosystem services from reefs,
mangroves and seagrass beds as well as loss
of livelihoods, food security and tourism value
(Obura et al., 2017).
1.4 Assessment of extinction risk: IUCN Red
List of Threatened SpeciesTM
the principles of extinction risk theory (Mace
et al., 2008) and are the most widely used and
objective system of quantifying extinction risk
across all taxa except microbiota (e.g., Butchart
There are nine Red List categories for global
Threatened (NT), Least Concern (LC), Data
2012).
Species that meet the quantitative thresholds
are assigned to one of the three threatened
come very close to, but do not fully meet the
thresholds for a threatened category, the Near
Threatened category is applied. When there
are no known major global-level threats, or
the known threats to a species do not reach
quantitative thresholds, a species is assessed as
Least Concern. When assessment data indicate
poorly understood due to taxonomic uncertainty
Criteria cannot be applied until further research
is conducted, and the species is assigned to
category is used to indicate a species that is
recognized as valid, but that has not yet been
assessed against the Red List Criteria (IUCN,
List.
3
Figure 2: The IUCN Red List Categories.
or both of the two premises of extinction risk
theory: elevated risk of extinction occurs when (1)
species’ populations are small and/or (2) species
have experienced, are experiencing or are likely
to experience population declines at rates that
are biologically infeasible for the population to
https://www.iucnredlist.org/resources/categories-
and-criteria for more information on Red List
Categories and Criteria). Criterion A is commonly
threat(s) that cause a population reduction
beyond a species’ ability to naturally sustain itself.
The decline is scaled to the life history of the
as the average age of the parents of a cohort.
Criterion B addresses species with restricted
geographic range that are also characterized by
habitat or individuals. Two metrics are used to
describe the spatial distribution of extinction risk.
area of a minimum convex polygon that contains
all known or inferred occurrences, and Area of
is inhabited by the species. Criterion C is applied
to species with a naturally small population size
and an observed, inferred or estimated continued
decline of the number of mature individuals in a
population. Criterion D addresses species with
extremely small and/or restricted populations, and
risk probabilities to estimate extinction risk.
1.5 Project objectives
The conservation status of several important
species that constitute the rich marine
biodiversity of the Western Indian Ocean is
overcome this scenario, the IUCN Red List has
formed the basis for many regional conservation
planning initiatives. Additionally, IUCN Red List
assessments are essential to Key Biodiversity
Area (KBA) analyses. KBAs can be designated
as targets needing conservation action to protect
biodiversity with a larger taxonomic scope.
Findings from this project could provide a unique
KBAs with broad taxonomic coverage.
IUCN Red List assessments are a key tool used
in local, national, regional, and global biodiversity
conservation. Regional or national Red Lists
often form the basis of national listings for
species-at-risk around the world. For example,
in the USA, global Red List assessments for
reef-building corals were used as the basis for
a successful petition to list 88 species of corals
Act. Some mega biodiverse countries, such as
Brazil, also rely on IUCN Categories and Red
List assessments in order to build their national
conservation strategies and environment action
plans (ICMBio/MMA, 2018). In the WIO region,
re-assessments of the Red List status of reef-
building corals are in development, which will
track progress towards the Aichi Biodiversity
Targets and post-2020 biodiversity goals. South
Africa has included Red List status of marine
species in support of its National Biodiversity
Assessment (Van der Bank et al., 2019), as
well as in supporting rationale for its recently-
expanded MPA network (Skowno et al., 2019).
4
Diodon hystrix
licensed under CC BY 2.0.
There is a distinct need for critical information
to help progress towards international targets
for biodiversity conservation, such as the United
Nations Sustainable Development Goals (SDGs)
and the Strategic Plan for the Convention on
Biological Diversity (CBD). The aim of this project
was therefore to assess the conservation status
of WIO marine species and, alongside existing
assessments for other key species groups,
present these data as the foundation for strategic
conservation in the Western Indian Ocean region.
•
• analyze trends in the conservation status
of all assessed marine biodiversity in the
• analyze trends in major threats and
conservation needs across species to
inform a state-of-knowledge report that can
support regional marine and coastal planning
• build an inter-disciplinary, inter-organizational
network of experts to champion the project
sustainably (e.g. mapping information).
5
Celebes Flathead (Thysanophyrs celebica
CC BY 2.0
2. Methods
2.1 Geographic scope
following Fischer and Bianchi (1984),
encompasses the United Nations Food and
51 as well as the entirety of Sri Lanka (Figure
includes 32 countries and territories, the majority
of which are considered developing economies
(UN, 2019). Major currents, including the Agulhas
Current, the Somali Coastal Current, the South
Current, impact the distribution and productivity of
biodiversity in the WIO.
2.2 Taxonomic scope
4,000 valid marine species in 10 taxonomic
and functional groups (Table 1). Within these
taxonomic groups, only valid species that are
primarily marine, native and present in the
published on the IUCN Red List are included.
Taxa below species level (i.e., subspecies) were
not assessed.
Taxonomy follows the standards adopted by
the IUCN Species Survival Commission (SSC)
Species Specialist Groups (SSGs) and Red List
taxonomic group. Higher taxonomic levels for
by Nelson (2006), and species-level taxonomy
follows that of the California Academy of
of Fishes (Fricke et al., 2020). It is expected that
the majority of Western Indian Ocean species
in these taxonomic and functional groups have
recently described or reported from the Western
Indian Ocean may have been omitted. As
the available assessments were supplemented
by three Red List assessment workshops focused
on species of the Western Indian Ocean.
6
Table 1: Number of Western Indian Ocean
species assessed in each of the 10 functional
groups included in this analysis.
Acanthurus sohal
under CC BY 2.0.
Functional Group Species
Mammals 46
Sea snakes 19
Sea turtles 5
2990
Sharks and rays 264
Cone snails 183
Sea cucumbers 125
Reef-building corals 492
Mangroves 26
Seagrasses 17
2.3 Preliminary assessments and
pre-workshop data collection
The IUCN Red List methodology is an objective,
data-driven process based on extinction risk
theory. For each species, the respective IUCN
species authority (e.g., Species Specialist Group
and/or Red List Authority) led the assessment
compiled into IUCN’s Species Information Service
(SIS) database, including data on the taxonomic
status and trends, habitats and ecology, threats
and conservation measures.
2.4 Red List assessment workshops
The species included in this analysis were
assessed during global, clade-based Red List
assessment workshops involving hundreds of
taxonomic experts from around the world. Three
Western Indian Ocean were held in Zanzibar,
participated in the three workshops (see
Appendix for participant lists for each workshop).
overview of the project’s aim and scope, as well
as a short training in the use and application
of IUCN Red List methodology. During the
remainder of the workshops, experts were
separated into groups based on their taxonomic
expertise. Guided by one of the facilitators, the
experts reviewed the preliminary assessments
generated during pre-workshop data collection
information as available. These data were then
used to determine if the thresholds and sub-
criteria were met for a threatened listing under at
least one Red List criterion for each species.
2.5 Post-workshop review
Following the workshops, each species’
assessment was edited, and outstanding
questions resolved through further consultations
with workshop participants, as well as with
members of the relevant Species Specialist
Groups and other experts who did not attend
the workshops. When necessary, distribution
review and consistency check completed by the
IUCN Red List Unit.
Three estimates for the proportion of threatened
species are used to account for the uncertainty
around the true extinction risk faced by Data
uses a midpoint and assumes the same
proportion of threatened species within the
categories. However, as the true status of Data
bound bracket of proportion threatened is also
calculated. The lower bound assumes that none
while the upper bound assumes that all Data
Table 2: The equations for the three estimates
of the proportion of threatened species based
on the IUCN Red List (IUCN, 2016). The
IUCN Red List categories include the three
Estimate Equation
Lower bound
Mid-point
Upper bound
7
2.6 Methodology for spatial analyses
and habitat preferences, were used to generate
distribution maps in ArcGIS 10.5 (software
assessments, coastal species are understood
as species residing relatively near the shore
in depths shallower than 200 m. Maps for
bathymetric layer, based on two-minute spatial
bathymetry data made available by the National
Marine Fisheries Service of the U.S. National
Oceanographic and Atmospheric Administration
either 100 km from the coast or the 200 m
depth contour, whichever was further from the
coastline. This approach standardizes the way
coastal species are mapped and produces
uniform and comparable distribution maps. For
pelagic and deep-sea species, distribution maps
were digitized by hand relative to known depth
preferences and habitat requirements.
Species richness analyses were conducted
toevaluate biodiversity patterns in the Western
Indian Ocean region for: 1) assessed marine
the three threatened categories (Critically
all richness analyses, each species’ distribution
map was transformed into the World Cylindrical
into a square grid raster of 10 x 10 km cell size.
was assigned a value of “1”. For each richness
analysis, the selected rasters were added
represented the number of species that occupy
each grid cell within the region.
8
Synodus variegatus
CC BY 2.0
3.1 Conservation status of marine biodiversity
Across the more than 4,000 assessed marine
species of the Western Indian Ocean included
Concern (LC). These are primarily widely
distributed and abundant species, or those with
no known major threats. The three threatened
categories account for a relatively small number
of species, with 25 assessed as Critically
195 as Vulnerable (VU). Another 197 species
nearly met the thresholds and conditions for a
threatened listing and were assessed as Near
Threatened (NT). The remaining species were
Based on these species, the best estimate for
for the uncertainty surrounding the true status
of the species listed as DD, the percentage of
the DD species are threatened.
listed under criterion A, indicating a past, present
or future projected population decline. The
remaining species were listed under criterion B
species were listed under multiple criteria.
3. Results and discussion
9
3.2 Trends by taxonomic group
The number of assessed species and estimates
of percentage threatened varied widely by
taxonomic group (Figure 4, Table 3). Across
the taxa included here, the highest and lowest
percentage of threatened species occurred in the
occur within the WIO were considered
threatened, while none of the 19 species of sea
snakes were considered threatened. Seven of
the 46 marine mammals, including cetaceans,
pinnipeds and sirenians, were listed as
10
Figure 4: Percentage of species listed in each of the IUCN Red List categories by taxonomic group. CR –
Table 3: Number of species and estimates of the percentage of threatened species for each taxonomic group
included here. The percentage of threatened species estimates follow the recommendations in IUCN (2016).
are threatened, respectively.
Taxon Species Lower Midpoint Upper
Mammals 46
Sea snakes 19
Sea turtles 5
2990
Sharks and rays 264
Cone snails 183
Sea cucumbers 125
Reef-building corals 492
Mangroves 26
Seagrasses 17
11
with over 17,000 valid species (Fricke et al.,
on about 2,200 species from southern Africa
(Namibia to Mozambique), Heemstra et al. (in
press) include well over 3,600 species of coastal
Heemstra, 1986), there are several pockets of
be described throughout the WIO, for example
Voronina, 2019) and Zanzibar, Tanzania (Tea et
al., 2019), indicating that our understanding of
from this region in the last decade. Among the
skates and chimaeras, the best estimate for the
Arabian Sea has one of the highest proportions of
et al., 2018). A relatively low proportion of bony
the nearly 3,000 species listed in a threatened
category.
Comprehensive conservation assessments
of invertebrates are limited in the WIO, with
assessments completed only for the cone
snails (Gastropoda: Conidae), sea cucumbers
(Holothuroidea), and reef-building corals
(Anthozoa: Scleractinia). In general, few cone
threatened.
The marine plants, mangroves and seagrasses,
are widely distributed in coastal regions. About
in the WIO region. These species provide
fundamental ecosystem services, including
processing, and sediment control, and support
around the globe (Costanza et al., 1997). Overall,
the risk of global extinction to these marine plants
remains low in the WIO, with only two species of
seagrasses listed as VU and one as DD.
Townsend’s Anthias (Pseudanthias townsendi
under CC BY 2.0
3.3 Spatial distribution of species
The highest richness of all assessed marine
species, with upwards of 1,300 species per 100
m², occurred in the tropics along the coast of
Lanka (Figure 5). Generally, richness was higher
The shallow, semi-enclosed Persian/Arabian Gulf
was an exception, with lower overall richness
its relatively young geological age and harsh
environmental conditions (e.g., Sheppard et al.,
2010).
12
Figure 5: Distribution of the marine species of the Western Indian Ocean that have been assessed against the
IUCN Red List Categories and Criteria.
Figure 6: Distribution of the threatened marine species of the Western Indian Ocean that have been assessed
against the IUCN Red List Categories and Criteria.
The east coast of Africa (Kenya, Tanzania and
Mozambique), the Western Indian Ocean Islands,
the Red Sea, the southern coasts of India and
the coastal regions of Sri Lanka were areas with
highest numbers of threatened species, with
higher richness of threatened species in coastal
the southern Red Sea and along the southern
coast of India, however, the number of threatened
species was higher than would be expected
based on the overall number of species alone.
13
assessed against the IUCN Red List Categories and Criteria.
distributed throughout the region, which may
be a result of the limited information available
regarding the distribution of many species
assessed as DD. Highest numbers of DD species
Lanka, followed by the Red Sea (Figure 7).
14
3.4 Threats
Threatened species are impacted by biological
resource use, either through direct, targeted
bycatch or habitat degradation (Figure 8). In
driver for all threatened and Near Threatened
these typically long-lived, late-maturing species
may be particularly susceptible to declines (e.g.,
Dulvy et al., 2014). The 237 threatened and
Near Threatened reef-building corals, which
represent nearly half of all the species in these
categories, are impacted by the same suite
and other problematic species, genes and
corridors.
Habitat degradation and destruction through
pollution, coastal development and other habitat
species groups assessed. These anthropogenic
activities can lead to physical damage, changes
in chemical water quality (eutrophication),
sedimentation, the introduction of pollutants,
and microbial contamination. Ultimately, habitat
loss can lead to ecosystem phase shifts in which
the dominant structuring species (i.e., corals,
seagrasses, and/or mangroves) are replaced
Phase shifts ripple through the ecosystem (Done,
1992), many causing a net loss of biodiversity as
2004).
Climate change further emerged as a major
driver of extinction risk for some taxa in some
sub-regions of the WIO. In the northwestern
WIO, climate change, aggravated by local
stressors such as coastal development, has been
implicated in the decline of coral assemblages
15
or Near Threatened that are impacted by various threats. Species are often impacted by more than one threat.
Burt et al., 2014). The Red Sea has high levels
of coral endemism (DiBattista et al., 2016), while
both regions have limited connectivity to other
parts of the WIO, and high and variable salinity
2001). Corals in these regions are vulnerable to
existing at the edge of the environmental and/
the southwestern WIO, South Africa has distinct
This biogeography contributes to high endemism
has led to shifting distributions of commercially
ecological, and economic impacts that complicate
resource management (Sink et al., 2012).
change, the survival of some species, such as
These taxa are likely to experience population
declines as a response to reduced habitat
16
Spotted Seahorse (Hippocampus kuda
2.0
3.5 Research needs
Our results highlight several key research needs,
including those for habitat-forming species and
exploited species. Approaches for economic
valuation can further contribute to biodiversity
conservation.
Habitat-forming species provide valuable
ecosystem services that support both human and
resolution information is available throughout
much of the WIO on the distribution and
abundance of these species. These research
needs should be elevated within existing
research and resource management frameworks
of the respective nation-states and territories of
the Western Indian Ocean region, and by regional
resource management organizations. Mangroves,
corals, and seagrasses primarily occur in shallow
waters, and as such a substantial portion of that
mandates of Regional Fisheries Management
Organizations (RFMOs) and arrangements
such as the Southern Indian Ocean Fisheries
Agreement, have the potential to enhance and
synthesize the highly variable existing knowledge
of the distribution of habitat-forming species.
For example, previous studies have highlighted
the need for a regional approach to coral reef
mapping in the Persian Gulf (e.g., Burt et al.,
Overexploitation of target and non-target marine
and NT species. Fishes, in general, had a high
proportion of species targeted in single- and
mammals, sea turtles and reef-building corals
were negatively impacted by incidental take as
activity, there is a pronounced need for greater
fundamental biological and ecological research
at multiple scales, from municipal to regional,
to support data-driven assessments of the
metrics such as maximum size, length-frequency
population trends is a crucial exercise that
supports resource management and conservation
programs, as well as the Red List assessment
process.
conservation by enabling the optimal allocation of
limited management resources. Loss of local or
regional biodiversity can result in a corresponding
loss in the provision of goods and services, some
of which have tangible economic value, including
reduced resilience and resistance to change,
potential, and lost recreational opportunities
Valuing these potential losses can empower
managers to divert resources towards important
and attainable biodiversity and ecosystem
services goals.
17
Malindi Fish Market, Zanzibar © G. Saluta.
3.6. Existing conservation tools
Municipal, provincial and state/territorial
environmental mandates, many of which are
focused on economic development, food security,
and poverty alleviation. Incorporating marine
biodiversity conservation goals and strategies
into existing policy and enforcing policies will
ensure continued ecosystem support for coastal
human communities, contribute to sustainable
development initiatives, and can bolster provincial
tourism.
The open ocean, or high seas, are cooperatively
managed by Regional Fisheries Management
Organizations, international organizations formed
in an area. RFMOs such as the Indian Ocean
Tuna Commission, and agreements such as the
Southern Indian Ocean Fisheries Agreement,
can implement management actions including
gear restrictions, as well as mandates to advance
research within their respective domains.
Both management and research functions of
these bodies have the potential to advance the
marine biodiversity and habitat conservation
in the region. Additionally, more regionally
and thereby achieve sustainable development
goals. One example of such a regional initiative is
that of the United Nations Industrial Development
Organization (UNIDO) project of the Republic of
Sudan, which is building institutional capacities
for an eco-system approach to management of
sustainable management and development of
2019).
Many WIO nations are signatories to international
environmental agreements, including the
Convention on Biological Diversity (CBD), the
Convention on Migratory Species (CMS), the
International Convention for the Regulation of
Whaling (IWC), the UN Convention on the Law
of the Sea (UNCLOS), and the UN Sustainable
Development Goals (SDGs). These agreements
have the potential to bolster marine conservation
goals of individual nation-states, promoting
regional cooperation, drawing political and
legal frameworks for use and governance in the
region’s oceans and seas.
Marine protected areas (MPAs) are another
recognized, dedicated and managed, through
long-term conservation of nature with associated
ecosystem services and cultural values (Dudley,
protected management of natural marine areas.
MPAs are created by delineating zones with
associated permitted and non-permitted uses
(IUCN Global Marine and Polar Programme,
2020). The countries and territories of the WIO
have designated many small, coastal protected
areas, as well as several large oceanic protected
areas, including the British Indian Ocean Territory
Africa’s recently expanded MPA network (IUCN,
cases, these protected areas have assisted
countries in meeting Aichi targets and SDGs.
18
3.7 Species conservation successes
Within the WIO various studies have investigated
and methods. In response to the major coral
bleaching event of 1998, Frontier-Tanzania
implemented surveys to measure the recovery
of corals within and outside of the Misali Island
Marine Conservation Areas (MIMCA) (Poonian,
pressure in the protected area sustained
overgrowth and thus promote coral recovery.
An assessment of locally managed marine areas
(LMMAs) in 2014 found that, though LMMAs
protect large areas, many are under-supported
by legal structures and enforcement mechanisms
One strong example of success in species
conservation and management in the region
comes from a Conservation Leadership
Programme (CLP) initiative. The CLP supported
the creation of a non-governmental organization
titled Community Centred Conservation or
C3. Operating in Comoros and Madagascar,
this NGO has used innovative approaches to
promote the conservation of species in the
region. C3 research on Dugong populations
was central in developing an international
protocol for rapid assessment of dugong
populations which is now used worldwide
(conservationleadershipprogramme.org accessed
further support from CLP expanded the work of
C3 to data collection for sharks and turtles in
addition to dugongs. Funding support facilitated
the employment of resource managers and eco-
guards as well as development of alternative
livelihood cooperatives. The work of C3 is
status of its target species within the Nosy Hara
hunting are now being recorded and reported.
Since the start of the project there have been
no recorded infractions within the park and
no reports of sea turtle or dugong mortality
(conservationleadershipprogramme.org accessed
Well-structured and strategically funded projects
such as this can be powerful tools for species
conservation. The above described project
focused on species of clear conservation priority
greatly from the information provided by the
conservation status report presented here. This
their risk of extinction, as well as key information
on the threats currently driving their decline.
19
Arothron stellatus
4.1 Overview
species across diverse taxonomic groups, 473
species that are threatened or Near Threatened
with extinction at the global level, according
to the IUCN Red List Categories and Criteria.
The status of species is based on evaluations
made by a network of experts who carried out
biodiversity assessments according to the IUCN
Red List Categories and Criteria. Complete
assessments are freely available on the IUCN
Red List website (http://www.iucnredlist.org).
The conservation status of in the WIO region
to the status of the same taxonomic suite of
species assessed in other regions. For example,
of threatened species in the Western Central
2020). However, uncertainty is highest in the
regions.
threatened species such as the southern Red
Sea and along the southern coast of India that
could be explored for prioritizing conservation
taxonomic group, and recommendations for
conservation actions are suggested. The data in
each species account provide key resources for
decision-makers, policymakers, natural resource
managers, environmental planners and NGOs.
4. Conclusions and recommendations
20
Tetrosomus gibbosus
CC BY 2.0
4.2 Application of project results
The value of the Red List extends far beyond
the assignation of threat status. The Red
List, in conjunction with the data gathered to
support it, has become an increasingly powerful
tool for conservation planning, management,
monitoring, and decision making (Rodrigues et
al., 2006). These assessments are valuable both
individually, and when aggregated for analyses,
such as those that have been presented in this
report.
National governments are the institutions
conservation action and legislation (Miller et
al., 2007). Species lists generated through the
IUCN Red List process can serve as a starting
point for the generation of national Red Lists
and lists of species of conservation concern
IUCN recommends use of the IUCN Guidelines
for Application of the IUCN Red List Criteria at
2003) when adapting global assessments to the
regional or national scale.
many problems currently facing biodiversity
(Bickford et al., 2012). Individual assessments
provide peer-reviewed information that can be
used in awareness and appreciation campaigns
conservation assessment for each species,
individual IUCN Red List accounts provide
concise summaries of geographic distribution,
population status, habitat and ecology, life history,
and uses and trade for each species, alongside
relevant, cited references found predominantly
assessments can be used by protected area
managers, zoos, aquariums, retailers and
wholesalers, tour guides, educational institutions,
and science communicators to raise biodiversity
and environmental awareness among audiences,
visitors, customers and clients (Bickford et al.,
2012). They can also be used as reference
material by researchers in biodiversity, ecology
Synthesizing Red List assessments provides
a powerful means for exploring, visualizing,
and summarizing trends across space, and
across species groups, as has been done for
this report. Some species that have undergone
re-assessment are candidates for analyses of
changes in conservation status over time and in
response to conservation action as part of the
Red List Index. Global-level analyses of Red
List results across entire clades contributes
widely to our understanding of extinction risk
of species richness and endemism (Polidoro et
2018), and presented novel patterns in use and
The results of this project serve as an important
baseline from which future assessments can
be compared, assessing trends in conservation
status over meaningful timescales and thus
measures over time.
aggregated Red List assessments for
delineation of Key Biodiversity Areas (KBAs).
of species composition that are either highly
vulnerable (threatened) or irreplaceable
(restricted range) and prioritize areas that will
et al., 2019). Red List assessments provide
foundational information regarding a species’
distribution, extinction risk status and plausible
threats for KBA analyses. In this regard, the
species assessments and analyses presented in
this report could inform KBA analyses for areas of
particular importance within the WIO.
21
4.3 General conservation strategies and tools
Various conservation strategies and tools are
relevant to addressing regional and global
biodiversity needs. The Red List assessments,
encompassing not only the threat status of a
species, but also the accompanying distribution,
life history, ecology, population trends, and
threat information, can and are being used to
guide resource management at multiple scales.
From assessments at a single site, such as
environmental impact assessments (Meynell,
2005) to national-scale evaluations, such as in
national development policies and legislation
and multilateral agreements (Rodrigues et
al., 2006), Red List assessments and the
associated temporal Red List Index, are essential
benchmarks.
The Red List Assessment process provides a
powerful tool for identifying knowledge gaps. For
example, despite their commercial importance,
many commercial species were assessed as
to apply the IUCN Red List criteria. Fisheries
population information within the context of
the Red List process and are the foundation of
However, in many cases, landings are recorded
only to the family or genus level, or species are
Red List can be used as a tool to prioritize
research needs for such species.
Raising awareness of the value and vulnerability
of the WIO’s marine biodiversity among resource
users, managers, the public, politicians, and
authorities is an ongoing conservation need.
on conservation strategies that are already
being employed at the local, national, and
Convention for the Protection, Management
and Development of the Marine and Coastal
and forum for such strategies. In collaboration
with, amongst others, the Western Indian Ocean
Marine Science Association, the South West
Indian Ocean Fisheries Commission, IUCN,
and the Convention on Biological Diversity, the
Nairobi Convention Secretariat leads initiatives
(past, current and future) such as the State of
the Coast Report, Outlooks on MPAs and Critical
Habitats, and the Strategic Action Plan for the
protection of the WIO, all of which heighten
awareness of biodiversity issues.
Strategies for raising awareness of the value
and vulnerability of the WIO’s marine biodiversity
include:
•
species is a species selected to act as an
habitat, issue, protected area campaign
• Hosting events designed to create awareness
of resident biodiversity and among a wide
range of communities, such as national
on regional biodiversity and existing
conservation tools and strategies.
• Incorporating biodiversity topics in
educational curricula for school-aged children
Matthies et al., 2011).
• Incorporating Red List Assessment
Categories of organisms on display in zoos
and aquariums (Whitehead, 1995).
• Deploying social media campaigns to
conservation issues (Bickford et al., 2012).
Areas for potential improvement in the
governance of the oceans and coastal
environment in the WIO region include
addressing policy and legislative inadequacies,
increasing institutional capacities, raising
resources and mechanisms, and improving
knowledge management. Translation of
22
international agreements and commitments into
national law is heterogenous across the region.
Continuing improvements in technical capacity,
strengthening of political will and prioritization,
and reduced political instability will contribute
to regional improvements in management of
WIOMSA, 2015). WIO Threatened Species
Task Forces have been suggested as means to
mobilize capacity to deal with threatened marine
WIOMSA, 2015).
4.4 Next steps
This report includes numerous new assessments
of marine species in the Western Indian Ocean,
representing a substantial contribution to
knowledge of the distribution, population status,
habitat, ecology, conservation status, threats, and
extinction risk of marine biodiversity in the region.
Despite this substantial taxonomic coverage,
there remain species and species groups that are
assessments, in particular, are lacking.
Completing these assessments, and performing
re-assessments at regular intervals, is a valuable
exercise that contributes to characterizing the
status of regional biodiversity and the relative
impact of conservation initiatives.
conservation in the marine environment are the
subsequent installation of marine protected area
(McLeod et al., 2009). KBAs are an iterative
and site-based methodology of identifying
where conservation measures will be most
assessments resulting from this study are integral
to completing the KBA process. Founded on
the concepts of vulnerability and irreplaceability,
KBAs enable conservation managers to identify
places where (a) conservation is most needed
to preserve biodiversity and (b) places where
marine areas can feasibly be managed and
protected (Langhammer et al., 2007). Where
managers and other stakeholders can delineate
a network of protected areas that encompass
of connectivity between the sites, as well as
passageways and refuge for highly mobile and
means of instituting protected areas for marine
in establishing and maintaining small, no-take
marine protected areas (Weeks et al., 2014).
23
Doryrhamphus excisus
licensed under CC BY 2.0
Whitespotted Grouper (Epinephelus
coeruleopunctatus
by D.P. Wilson and licensed under CC BY 2.0.
The IUCN Red List of Threatened SpeciesTM
to share the knowledge gathered by its global
community of over 10,000 scientists and
conservation professionals. Training in the
application of biodiversity data sets to species
and site-based management and enforcement
activities is available through the IUCN
Conservation Planning Specialist Group, the
IUCN Species Monitoring Specialist Group, and
the IUCN World Commission on Protected Areas/
on Biodiversity and Protected Areas.
The following reference documents provide
valuable tools for using IUCN Red List
Assessments to inform area-based conservation
measures:
• A Global Standard for the Identication of Key
Biodiversity Areas. Version 1.0 (2016)
• Guidelines for Applying Protected Area
Management Categories (2008)
• Guidelines for applying the IUCN protected
area management categories to marine
protected areas. Second edition (2019)
For more information on using the IUCN Red List
of Threatened SpeciesTM to inform conservation
planning, including KBAs and protected areas,
please reach out to the following:
• IUCN Global Marine and Polar Programme
• IUCN Marine Conservation Committee
• World Commission on Protected Areas –
Marine Division
• Species Survival Commissions (SSC)
Specialist Groups
•
Oceans Law and Governance Specialist
Group
24
Dhow © G. Saluta.
Chumbe Island Coral Park Nature Reserve and
Reef Sanctuary © G. Saluta
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30
Appendix: Expert participants
31
Participant Name Aliation Country
Old Dominion University/IUCN USA
Philippe Borsa France
Robert Bullock The Deep Aquarium/IUCN
Kent Carpenter Old Dominion University/IUCN USA
Fabio Di Dario Brazil
Institute of Marine Sciences, University of Dar es Salaam Tanzania
Moazzam Khan WWF-Pakistan Pakistan
Helen Larson Museum and Art Gallery of the Northern Territory Australia
Keiichi Matsuura National Museum of Nature and Science
Hiroyuki Motomura The Kagoshima University Museum
Clay Obota Coastal Oceans Research and Development - Indian Ocean (CORDIO) Kenya
Beth Polidoro Arizona State University/IUCN USA
Gina Ralph Old Dominion University/IUCN USA
William Smith-Vaniz Florida Museum of Natural History, University of Florida USA
Saleh Yahya Institute of Marine Sciences, University of Dar es Salaam Tanzania
Workshop group photo in Zanzibar © G. Ralph.
32
Participant Name Aliation Country
Farid Saud Hamed Al
Abdali
Oman
Oman
Asma Al Bulushi Oman
Bader Al Buwaiqi Oman
Abdullah Sulaiman
Musbah Al Kindi
Oman
Aisha Ambuali Oman
Philippe Borsa France
Kent Carpenter Old Dominion University/IUCN USA
Anesh Govender Oman
Helen Larson Australia
Christi Linardich Old Dominion University/IUCN USA
Beth Polidoro Arizona State University/IUCN USA
Gina Ralph Old Dominion University/IUCN USA
Barry Russell Australia
Alan Williams Australia
Workshop group photo in Muscat © G. Ralph.
33
Participant Name Aliation Country
Robert Bullock The Deep Aquarium/IUCN
South African Association for Marine Biological Research Oceanographic
Research Institute South Africa
Sean Fennessy South African Association for Marine Biological Research Oceanographic
Research Institute South Africa
Catarina Fonseca Oceanario de Lisboa/IUCN Portugal
Claire Gorman Old Dominion University/IUCN USA
Hans Ho Institute of Marine Biology, National Dong Hwa University Taiwan
Wouter Holleman South African Institute for Aquatic Biodiversity South Africa
Christi Linardich Old Dominion University/IUCN USA
Patroba Matiku Tanzania Fisheries Research Institute Tanzania
Claque Maunde National Institute of Fisheries Research Mozambique
Thomas Munroe U.S. National Marine Fisheries Service/Smithsonian Institution USA
Rekha Nair India Central Marine Fisheries Research Institute India
Gina Ralph Old Dominion University/IUCN USA
Barry Russell Australia
Yonela Sithole South African Institute for Aquatic Biodiversity South Africa
Franz Uiblein Institute of Marine Research Norway
Steven Weerts South Africa
Alan Williams Australia
Workshop group photo in Durban © G. Ralph
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