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Shark diversity in the Arabian/Persian Gulf higher than previously thought: insights based on species composition of shark landings in the United Arab Emirates

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Although fish fauna in the Arabian/Persian Gulf have been studied for decades, shark diversity has only been recently investigated in the region. Here, we present a first comprehensive account of shark diversity from the United Arab Emirates based on fishery-dependent data collected at market and landing sites over a two-year period of field sampling. Landings across the country were dominated by carcharhinids, and six species were found to be most abundant, including the spot-tail shark, Carcharhinus sorrah, and the milk shark, Rhizoprionodon acutus, contributing 31.8 % and 29.9 %, respectively, of the total number of sharks. While observed landings varied among regions and across seasons, results showed that shark landings were dominated by small-sized species, which may be a reflection of overexploitation. We are now expanding the existing checklist of shark species in the Persian Gulf from 27 to 31, having utilized both morphological identification and genetic barcoding in validating the existence of the grey bamboo shark, Chiloscyllium griseum; the tawny nurse shark, Nebrius ferrugineus; the silky shark, Carcharhinus falciformis; and the sandbar shark, Carcharhinus plumbeus, in these waters. This inventory provides an urgently needed assessment of current regional diversity patterns that can now be used as a baseline for future investigations evaluating the effect of fisheries on shark populations. Results emphasize the need for research on life history traits of the various species in order to determine their regional conservation status, but also reveal that a precautionary approach to conservation will be necessary to mitigate anthropogenic impacts.
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Shark diversity in the Arabian/Persian Gulf higher than
previously thought: insights based on species composition of shark
landings in the United Arab Emirates
Rima W. Jabado &Saif M. Al Ghais &Waleed Hamza &
Mahmood S. Shivji &Aaron C. Henderson
Received: 30 July 2014 /Revised: 29 August 2014 /Accepted: 23 September 2014
#Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg 2014
Abstract Although fish fauna in the Arabian/Persian Gulf
have been studied for decades, shark diversity has only been
recently investigated in the region. Here, we present a first
comprehensive account of shark diversity from the United
Arab Emirates based on fishery-dependent data collected at
market and landing sites over a two-year period of field
sampling. Landings across the country were dominated by
carcharhinids, and six species were found to be most abun-
dant, including the spot-tail shark, Carcharhinus sorrah,and
the milk shark, Rhizoprionodon acutus, contributing 31.8 %
and 29.9 %, respectively, of the total number of sharks. While
observed landings varied among regions and across seasons,
results showed that shark landings were dominated by small-
sized species, which may be a reflection of overexploitation.
We are now expanding the existing checklist of shark species
in the Persian Gulf from 27 to 31, having utilized both mor-
phological identification and genetic barcoding in validating
the existence of the grey bamboo shark, Chiloscyllium
griseum; the tawny nurse shark, Nebrius ferrugineus; the silky
shark, Carcharhinus falciformis; and the sandbar shark,
Carcharhinus plumbeus, in these waters. This inventory pro-
vides an urgently needed assessment of current regional di-
versity patterns that can now be used as a baseline for future
investigations evaluating the effect of fisheries on shark pop-
ulations. Results emphasize the need for research on life
history traits of the various species in order to determine their
regional conservation status, but also reveal that a precaution-
ary approach to conservation will be necessary to mitigate
anthropogenic impacts.
Keywords Shark .Species richness .United Arab Emirates .
Management .Conservation
The Arabian/Persian Gulf (hereinafter referred to as the
Gulf) is a highly stressed ecosystem as a result of the
prevailing environmental conditions as well as the anthropo-
genic activities that have introduced a number of stressors
threatening its ecological integrity and sustainability (Hamza
and Munawar 2009). With the rapid economic growth that has
taken place in the eight bordering countries of Iran, Iraq,
Kuwait, Saudi Arabia, Bahrain, Qatar, the United Arab Emir-
ates (UAE), and Oman, the marine environment is swiftly
Although the overall biodiversity at the species level is still
poorly understood compared to that of the Arabian Sea, the
Gulf is considered biologically impoverished, in part because
of its young age, but primarily due to its environmental
characteristics (Randall 1995; Sheppard et al. 2010). It is
believed that most organisms living in the Gulf survive at
Electronic supplementary material The online version of this article
(doi:10.1007/s12526-014-0275-7) contains supplementary material,
which is available to authorized users.
R. W. Jabado (*):S. M. Al Ghais :W. Hamza
Biology Department, College of Science, United Arab Emirates
University, P.O. Box 15551, Al Ain, United Arab Emirates
M. S. Shivji
Save Our Seas Shark Center, Nova Southeastern University
Oceanographic Center, 8000 North Ocean Drive, Dania Beach,
FL 33004, USA
A. C. Henderson
The School for Field Studies, Center for Marine Resource Studies,
South Caicos, Turks and Caicos Islands
Present Address:
R. W. Jabado
Gulf Elasmo Project, P.O. Box 29588, Dubai, United Arab Emirates
Mar Biodiv
DOI 10.1007/s12526-014-0275-7
the limits of their physiological tolerance and that marine taxa
here are derived from the penetration of Indian Ocean species
through the Strait of Hormuz (Price 1993; Beech 2004a).
Basson et al. (1977) reported low species richness in these
waters, which was confirmed by most later research on ben-
thic groups such as corals and echinoderms (Price and Coles
1992; Sheppard et al. 1992). On the other hand, the Gulf is
also recognized as home to at least four species of marine
turtles, over 10 cetacean species, the second-largest dugong
population in the world, as well as large numbers of endemic
and migratory birds, suggesting that it could be harboring high
levels of marine biodiversity (Hellyer and Aspinall 2005).
From a fisheries perspective, various research projects have
indicated that anywhere from 200 and up to 550 species have
been reported in the Gulf, including reef-associated fishes,
sharks, and rays (Krupp et al. 2000; Grandcourt 2012). In com-
parison to the fish fauna documented in Omans Arabian Sea, it is
clear that the Gulf is limited in its fish biodiversity, and few
species are endemic to these waters (Randall 1995; Carpenter
et al. 1997; Bishop 2003; Beech 2004b). Furthermore, it appears
that there are regional variations in species richness throughout
the Gulf, with fewer species identified in western and southern
areas, while northern and eastern areas, as well as the deeper
waters closer to the Strait of Hormuz, are richer in certain species
(Price 1993; Beech 2004b). This is believed to be related to
several factors, including bottom topography and sediment type
in the Gulf (Beech 2004b).
Fisheries in the region are described as artisanal, multi-gear,
and multi-species (Beech 2004b;Grandcourt2012). Fishermen
operate two types of boats: small fiberglass dories, or tarad,
and traditional wooden dhows, or lansh(Grandcourt 2012;
Jabado et al. 2014). The primary fishing gear utilized on these
vessels include drift nets, gill nets, handlines, traps, longlines,
and trolls (Jabado et al. 2014). Although sharks are an important
component of fisheries and fish trade, their diversity in the Gulf
is still poorly understood (Jabado et al. 2014).Basedona
literature review and results from market surveys, the most
recent account of shark species in this basin confirms the pres-
ence of 26 species (Moore et al. 2012b). Although these reports
are based on limited observations and do not reflect changes in
geographic and temporal trends that may be occurring in the
basin, they do hold relative value, as they remain the only
species records and measures of abundance levels for sharks in
the region. Furthermore, despite the fragmented nature of these
surveys, the rate of species discovery is relatively high, with
recent documentation and confirmation of new shark species,
including the slender weasel, Paragaleus randalli (Compagno,
Krupp and Carpenter, 1996); sliteye, Loxodon macrorhinus
(Müller and Henle, 1839); snaggletooth, Hemipristis elongatus
(Klunzinger, 1871); graceful, Carcharhinus amblyrhynchoides
(Whitley, 1934); and hardnose, C. macloti (Müller and Henle,
1839) (Compagno et al. 1996; Moore et al. 2010). More recent-
ly, a new species of whaler shark, Carcharhinus humani sp. nov.
(White and Weigmann 2014), was also described in the Gulf,
bringing the total number of species to 27 (White and
Wei g mann 2014). The limited amount of research currently
being directed toward shark diversity, distribution, and biology
gives rise to doubts about the completeness and accuracy of
available regional checklists (Jabado et al. 2014). In the UAE,
there is no established list of shark species other than some
confirmed sightings within the Gulf recorded during a survey
conducted in 2002 by the Environment Agency Abu Dhabi
(EAD) (Edwin Grandcourt, pers. comm.) and during a 10-day
visit to a landing site in Abu Dhabi by Moore et al. (2012a). This
general lack of knowledge on the number of shark species,
composition and quantities of catches, and the amount of fishing
efforts directed toward this fishery suggests that shark species
richness in the region could be higher than previously recorded.
This is especially true since it has been shown around the world
that with increased research and genetic studies, new species are
being discovered and described at a rapid rate (Naylor et al.
Globally, shark populations are facing increasing pressure,
and the advancement of conservation measures requires infor-
mation on their biodiversity and conservation status
(Simpfendorfer et al. 2011). In the UAE, fishermen have
indicated a general decline in shark catches, abundance, and
size over the last two decades, suggesting that the shark
fishery is currently overexploited (Jabado et al. 2014). How-
ever, protection of sharks in the Gulf is hampered by limited
available baseline scientific data, along with the challenge of
balancing conservation efforts with the provision of essential
resources for growing coastal populations. In order to main-
tain the ecological integrity of the Gulf, it is essential to
understand and evaluate potential changes in the marine bio-
diversity of this increasingly threatened aquatic ecosystem.
Here, we investigate the diversity of shark species captured
in the UAE artisanal fishery. We present the results of fishery-
dependent market and fish landing site surveys that can aid in
conservation initiatives both in the UAE and in the broader
region. Specifically, we (1) examine patterns of species com-
position, distribution, and relative abundance across sites; (2)
investigate temporal and spatial variability in landings com-
position; and (3) validate the field identification of each spe-
cies through genetic analysis of a representative sample of
individual species using the Cytochrome c oxidase subunit 1
gene (COI). We conclude with a discussion of general impli-
cations for the conservation of shark species in the Gulf.
Material and methods
Study sites
The Gulf is an epicontinental semi-enclosed sea lying in a
subtropical zone with hyper-arid climate, stretching 1,000 km
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in length from the Shatt al-Arab waterway to the Strait of
Hormuz, and varying in width from 75 to 350 km (Carpenter
et al. 1997)(Fig.1). The basin has an average depth of 35 m,
gradually becoming deeper, to 100 m, as it approaches its
entrance (Sheppard et al. 1992).Themarineenvironmentis
harsh and extreme, characterized by low hydrodynamic ener-
gy; relatively shallow depths; high evaporation rates, surface
water temperatures, and salinities; and minimal water
The UAE lies along the southeastern Gulf coast and ex-
tends to the Gulf of Oman between 22° and 26° N latitude
and 51° and 57° E longitude. The countrys coastline stretches
roughly 740 km, including some 650 km of the western Gulf
coast (EAD 2011). The main study area was along the Gulf
coastline of the UAE. From April through June 2010, several
exploratory market and landing site visits were carried out to
determine sites with the largest concentrations of shark land-
ings. It was subsequently determined that this study would
focus on landing sites in the regions nationally defined as
Western (Mina Zayed, Abu Dhabi), Central (Jubail, Sharjah),
and Northern (Maarid, Ras Al-Khaimah (RAK)). While sev-
eral landing sites exist within each region, these three loca-
tions are found along the Gulf coastline where vessels offload
their catches directly, facilitating the collection of information
on capture location. Vessels operating and offloading in this
area fish exclusively in Gulf waters, and thus it was possible to
ensure that all species recorded were from the waters of the
Gulf and not the Arabian Sea. Furthermore, fishers from
nearby landing sites transport their landings to these markets
at the time of auction, enabling sampling of larger numbers of
specimens during each survey. Species composition of land-
ings from Dubai, as well as from specimens transported to
Dubai from these three regions, were opportunistically record-
ed at the Dubai Deira fish market while conducting separate
trade surveys and were included in this analysis.
Market and landing site surveys
Site visits were made prior to the start of the main daily
auction, when the majority of landings were on display, and
were at different times: 04:3008:00 in Abu Dhabi, 16:00
18:30 in Sharjah, 12:3015:00 in RAK, and 17:0020:00 in
Dubai. All sharks found at landing sites were caught from
UAE Gulf waters, whereas those found at markets were
sometimes transported from other emirates or from Oman.
Data were recorded on the origin of each shark at the markets,
and only those captured in UAE waters were considered in
this study.
Data collection commenced in October 2010 and was
ongoing until September 2012. With the exception of sites in
Dubai, each site was visited twice a month on a rotational
basis until January 2012, when visits were reduced to once a
month. In Dubai, data were collected four times a month, and
then reduced to twice a month in January 2012. After plotting
the cumulative number of species present at each market visit
against the number of market visits, it was determined that
even with a reduction in sampling frequency, surveys would
be sufficient to describe species composition at landing sites.
Each visit lasted three to four hours, depending on the quantity
of sharks landed. Specimens were always landed whole, and
therefore it was possible to identify them to the lowest possi-
ble taxonomic level using keys from Carpenter et al. (1997),
Compagno et al. (2005), and Last and Stevens (2009). Be-
cause shark trade among the emirates does occur, sharks
sampled were marked with cuts on their left gills, and visits
to markets did not occur on consecutive days and weeks in
order to avoid double-counting study specimens.
An analysis of species richness was undertaken using
Jaccards similarity index to determine the percentage of spe-
cies shared between landing sites (Magurran 2004). In addi-
tion, landings composition was compared across seasons,
which were defined as spring (MarchMay), summer (June
August), autumn (SeptemberNovember), and winter (De-
cemberFebruary). Full seasons were sampled for both years,
with the exception of autumn, which was sampled for two
months in 2010 and one month in 2012 due to the limited time
frame of the project.
Genetic analyses
Tissue samples were collected from fresh animals at the four
sampling sites. All samples were immediately placed in
Eppendorf Tubes, preserved in 95 % ethanol, and stored at
20 °C until required for analysis. To validate species identity,
a set of 130 tissue samples comprising five samples from each
morphologically identified species, when available, were
Genomic DNA was extracted using the DNeasy Blood &
Tissue Kit (Qiagen Inc., Valencia, CA, USA) from 25 mg of
fresh tissue collected from whole specimens, according to
manufacturer instructions. Extracted DNA was checked on
0.8 % TBE agarose gels containing ethidium bromide for
DNA quality and concentration. A DNA fragment from the
COI gene comprising approximately 650 bp was amplified by
PCR using the individual primers Fish F1 (5-TCAACCAA
Amplification reactions were performed in50-μLvolumes,
containing 1 μL of the extraction genomic DNA, 10 pmol of
each primer, 10X PCR buffer (Qiagen Inc.), 50 μMdNTPs
mix (Illustra dNTP set, GE Healthcare), 1 unit of HotStarTaq
DNA Polymerase kit (Qiagen Inc.), and 33.3 μLHPLCpuri-
fied water (OmniSolv). The PCR thermal cycling employed
was: 95 °C initial denaturation for 15 min, followed by
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35 cycles of 94 °C for 1 min, 50 °C for 1 minute, 72 °C for
2 min, and a 2-min final extension step at 72 °C. Amplifica-
tions were performed using the BioRad iCycler thermal cy-
cler. Amplified fragments were confirmed on 1.2 % agarose
gel stained with ethidium bromide and viewed on a Foto/
spectrum Transilluminator (FotoDyne). PCR reactions were
cleaned with QIAquick PCR Purification Kit (Qiagen) and
eluted in 30 μL of Buffer EB. For each sample, 10 μLof
cleaned cycle sequencing reaction per well was loaded in a
MicroAmp 96-Well Reaction Plate (Applied Biosystems,
USA), and sequencing was completed using the dye-labeled
termination method (BigDye Terminator v3.1, Cycle Se-
quencing Kit, Applied Biosystems) on a 3130xl Genetic
Analyzer (Applied Biosystems) in either forward or
reverse direction.
Sequences were inspected and cleaned of ambiguous bases
by visualizing the corresponding chromatogram using the
BioEdit program (Hall 1999). Species identification was per-
formed using both the BOLD Identification Engine (www. and GenBank nucleotide database (www.
ncbi.nlm.nih.ggoc/nucleotide). The BOLD and GenBank
engines each matched uploaded sequences with others
present in their databases, and provided high specimen
similarity or maximum identity percentages, respectively,
with matching sequences. All sequences were then aligned
using Clustal XI software and trimmed to 417 bp in order to
include as many species in the analysis as possible without
compromising its power. Taxonomic clustering among
barcoded samples was analyzed by constructing
phylogenetic trees using three different methods: neighbor-
joining (NJ), maximum likelihood (ML) and maximum par-
simony (MP). Estimation of the NJ (Kimura two-parameter
distance model [Kimura 1980]) and MP trees was performed
using 1,000 bootstrap replications (MEGA 4) (Tamura et al.
Overall species composition
A total of 12,478 individual sharks originating from UAE
Gulf waters were recorded from 205 site visits. After 150
visits, from which 28 species of sharks were confirmed, the
frequency of surveys was reduced, as it was determined that
extra market visits would not serve to increase the diversity of
species encountered. An additional two species were docu-
mented in 2012, however, raising the number of confirmed
species to 30, which consisted of nine families from three
orders (Table 1). The family Carcharhinidae was the most
diverse, with 18 species, followed by Hemigaleidae with
three species, and Sphyrnidae and Hemiscylliidae with
two species each.
Fig. 1 Map indicating the
location of landing sites across the
UAE where sampling was
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Tabl e 1 Taxonomic list of shark species, including IUCN Red List Status, recorded from UAE waters from 205 surveys
Family/Species IUCN status Abu Dhabi Dubai Sharjah Ras Al-Khaimah Autumn Winter Spring Summer TOTAL
n%n%n%n%n %
NT 1 3 1 0 1 0.02 2 0.06 1 0.02 1 0.04 50.04
NT 0 0 1 0 0 0.0 0 0.0 1 0.02 0 0.0 10.01
Nebrius ferrugineus VU 0 0 2 0 0 0.0 1 0.03 0 0.0 1 0.04 20.02
VU 0 5 4 0 1 0.02 0 0.0 7 0.2 1 0.04 90.07
Rhincodon typus VU 0 1 0 0 0 0.0 1 0.03 0 0.0 0 0.0 10.01
Carcharias taurus VU 1 0 0 0 0 0.0 0 0.0 1 0.02 0 0.0 10.01
Mustelus mosis DD 1 17 55 131 37 0.9 48 1.6 101 2.8 18 0.8 204 1.63
VU 2 7 23 28 8 0.2 25 0.8 21 0.6 6 0.2 60 0.48
Hemipristis elongata VU 3 5 26 15 18 0.47 7 0.2 13 0.3 11 0.4 49 0.39
Paragaleus randalli NT 0 9 22 54 9 0.23 17 0.5 31 0.8 28 1.2 85 0.68
Carcharh inidae
NT 33 8 41 8 15 0.39 6 0.2 62 1.7 7 0.3 90 0.72
NT 0 4 3 1 3 0.07 0 0.0 0 0.0 5 0.2 80.06
DD 61 16 42 8 19 0.5 32 1.0 61 1.7 15 0.6 127 1.02
NT 8 33 17 8 6 0.15 12 0.4 36 1.0 12 0.5 66 0.53
NT 136 63 212 150 187 4.94 189 6.3 96 2.7 86 3.8 561 4.50
NT 0 6 0 0 6 0.15 0 0.0 0 0.0 0 0.0 60.05
VU 1 2 0 0 2 0.05 1 0.03 0 0.0 0 0.0 30.02
Carcharhinus le ucas NT 93 44 18 12 19 0.5 62 2.0 68 0.0 18 0.8 167 1.34
NT 906 300 516 64 581 15.3 455 15.3 516 14.7 234 10.4 1786 14.31
NT 0 60 11 102 73 1.93 42 1.4 43 1.2 15 0.6 173 1.39
NT 10 15 10 3 8 0.2 5 0.1 9 0.2 16 0.7 38 0.3
VU 1 0 6 6 4 0.1 5 0.1 1 0.02 3 0.1 13 0.1
Carcharhinus sorrah NT 615 716 1460 1182 997 26.3 675 22.7 1179 33.7 1122 50.2 3973 31.84
Galeocerdo cuvier NT 0 0 1 0 0 0.0 0 0.0 1 0.02 0 0.0 10.01
LC 8 320 88 704 415 10.9 235 7.9 270 7.7 200 8.9 1120 8.98
Negaprion acutidens VU 30 3 7 1 19 0.5 4 0.1 11 0.3 7 0.3 41 0.33
LC 818 870 989 1060 1315 3.46 1083 36.4 924 26.4 415 18.5 3737 29.95
LC 0 0 1 11 4 0.1 8 0.2 0 0.0 0 0.0 12 0.1
Sphyrna lewini EN 0 7 2 6 8 0.2 1 0.03 4 0.1 2 0.08 15 0.12
Sphyrna mokarran EN 80 8 30 6 17 0.4 50 1.6 45 1.2 12 0.5 124 0.99
TOTAL 2808 2522 3588 3560 3782 30.3 296 8 23.7 3495 2 8.0 2233 17. 8 12478 100
(EN Endangered; NT Near Threatened; VU Vulnerable; DD Data Deficient; LC Least Concern); species composition and quantities of sharks recorded
in Abu Dhabi, Dubai, Sharjah, and Ras Al-Khaimah, based on their location of origin, seasonal and total catch composition (n= number of individuals; %
of shark landings)
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Carcharhinids dominated landings in terms of number,
with 95.5 % (n=11,922) of the total shark landings, followed
by the triakids, consisting of one species, Mustelus mosis
(Hemprich and Ehrenberg, 1899), but accounting for 1.6 %
of the total landings. While the total number of species was
relatively high, many of them were found only in small
quantities and landings were dominated by a few species.
The most abundant species was Carcharhinus sorrah (Müller
and Henle, 1839), contributing 31.8 % to the total number of
sharks, followed by Rhizoprionodon acutus (Rüppell, 1837),
with 29.9 % of the total. In terms of number, C. limbatus
(Valenciennes, 1839), L. macrorhinus,C. dussumieri (Valen-
ciennes, in Müller and Henle, 1839), and M. mosis were also
relatively abundant, contributing 14.3 %, 8.9 %, 4.5 %, and
1.6 %, respectively, to the total shark numbers. The remaining
24 species comprised between 0.01 % and 1.4 % of the total
shark landings.
Spatial and seasonal species composition
With respect to the 30 shark species identified, Sharjah was
the region most rich in species, with a total of 26 species,
followed closely by Dubai, with 24 species. RAK had 21
species, while Abu Dhabi displayed the lowest species rich-
ness, with 19 species recorded. With regard to the similarity in
species composition among landing sites, Jaccards index
indicated that the degree of species overlap among regions
was moderately high, with regions sharing anywhere from
60.7 % to 80.7 % of species (Table 2).
Although the sampling effort was consistent in each loca-
tion and cross-seasonally, there was some degree of variability
in the number of observed landings among regions and across
seasons (Table 1). Among regions, Dubai had the fewest shark
landings, with 20.2 % of the total, followed by Abu Dhabi
with 22.5 %. When viewed from a regional perspective, the
Central region, comprising both the Dubai and Sharjah land-
ing sites, contributed 49.5 % of the total number of landings.
There was no significant difference in the number of spe-
cies across seasons, with 25 species recorded in autumn, 24 in
both winter and spring, and 23 in summer. There was varia-
tion, however, in the total number of landings, with autumn
yielding the highest number, with 30.3 % of the total captures,
whereas a significant decline was observed in the summer
(17.8 %). The numbers also varied with regard to seasonal
shark landings by site location. Abu Dhabi had the highest
landings in autumn (37.9 %), followed by winter (31.1 %) and
spring (25.9 %), while almost no shark landings were record-
ed in the summer (4 %). In Dubai, landings were stable during
autumn (30.9 %) and spring (32 %), but declined during
winter (16.2 %) and summer (20.7 %). Landings in Sharjah
were relatively stable across seasons, although spring yielded
the highest number, with 29 % of the total, followed by
summer (25.7 %), winter (23.8 %), and autumn (21.4 %).
RAK showed a different pattern as well, with landings
peaking in autumn (32.7 %), followed by spring (27 %),
winter (23 %), and summer (17.2 %). When landings in Dubai
and Sharjah were combined, Central region numbers showed
similar patterns to RAK, with a peak in spring (30.2 %), but
then followed by autumn (25.3 %), summer (23.7 %), and
winter (20.7 %) (Fig. 2).
Overall species composition varied across locations and
seasons. While six species dominated overall among the land-
ings, some variability in the dominant species was noted with
regard to regional occurrence and abundance (Fig. 3). The
most frequently observed species at all sites were C. sorrah
and R. acutus. With the exception of landings of M. mosis and
C. macloti, the most abundant species were similar between
Dubai and Sharjah, and landings composition for these two
sites were combined as the Central region.
Noteworthy species occurrence included M. mosis, ac-
counting for a low proportion of catches in most locations
(n= 1 in Abu Dhabi) but common in RAK, thereby increasing
its abundance in the national catch composition overall;
C. macloti, which was absent in Abu Dhabi landings but
was recorded at all other locations across seasons, with
58.9 % of catches recorded in RAK; C. leucas (Müller and
Henle, 1839), which was found in catches across seasons but
predominantly in Abu Dhabi (55.6 %), where it was abundant;
C. leiodon (Garrick, 1985), which was only present in Dubai
and Abu Dhabi in autumn and winter; C. falciformis (Müller
and Henle, 1839), which was recorded in Dubai in autumn but
not present at other landing sites or during other seasons;
R. oligolinx (Springer, 1964), which was only found in RAK
(n=11) and Dubai (n=1) during autumn and winter; and
Tabl e 2 Jaccards similarity index values illustrating the degree of sim-
ilarity in the species composition among sampling sites in the UAE
Abu Dhabi Dubai Sharjah Ras Al-Khaimah
Abu Dhabi * 0.65 0.60 0.66
Dubai * * 0.72 0.73
Sharjah * * * 0.80
Ras Al-Khaimah * * * *
Abu Dhabi Dubai Sharjah Ras Al
Central region
Number of sharks
Fig. 2 Seasonal shark landings recorded for each landing site location,
with Dubai and Sharjah landings shown separately as the Central region
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P. randalli,C. amblyrhynchos (Bleeker, 1856), and Sphyrna
lewini (Griffith and Smith, 1834), which were not recorded in
Abu Dhabi but present at other sites.
Range extensions and new species confirmations in the Gulf
Four previously unconfirmed species in this basin were re-
corded, extending their current known distribution. They in-
cluded the grey bamboo shark, Chiloscyllium griseum (Müller
and Henle, 1839);the tawny nurse shark, Nebrius ferrugineus
(Lesson, 1830);the silky shark, C. falciformis; and the sand-
bar shark, C. plumbeus (Nardo, 1827). Furthermore,
Galeocerdo cuvier (Peron and Lesueur, 1822) and
C. amblyrhynchoides specimens were confirmed for the first
time in southern Gulf waters.
DNA Barcoding
DNA COI barcoding was attempted on 130 samples from the
30 species identified morphologically in this study. The final
barcode data set comprised 120 sequences from 29 species,
with sequence lengths varying from 485 to 637 bp. Sequences
have been deposited in the GenBank database under accession
numbers: KM973088-KM973199. Ten samples were exclud-
ed from the analysis: three of them yielded ambiguous species
identifications, while seven samples failed to provide good
sequences, including the only sample of C. griseum collected.
All sequences were compared with those in BOLD and GenBank
databases to confirm initial morphological identification, and the
results of matching sequences, along with the amplicon size
produced for each sample, are provided in Appendix A.
Genetic analysis based on morphological characteristics un-
equivocally confirmed 24 species among those recorded in this
study. Of these, 12 sequences were the first available from the
Gulf for C. arabicum (Gubanov and Schleib 1980),
N. ferrugineus, Stegostoma fasciatum (Hermann, 1783),
Rhincodon typus (Smith, 1828), Carcharias taurus (Rafinesque,
1810), C. amblyrhynchos, C. falciformis, C. melanopterus (Quoy
and Gaimard, 1824), C. plumbeus, Negaprion acutidens
(Rüppell, 1837),G.cuvier,and S. lewini. Taxonomic identifica-
tion from barcodes, however, was ambiguous for five species.
Only two of five samples of C. arabicum provided good
sequence quality, and although results from both BOLD and
GenBank assigned these sequences to the Chiloscyllium ge-
nus, species resolution was not possible. Rhizoprionodon
oligolinx sequences provided a 100 % match with the same
species in BOLD, but the closest match in GenBank was 93 %
with R. porosus (Poey, 1861). For P. randalli and
Chaenogaleus macrostoma (Bleeker, 1852), there was no
consistency in the nomenclature of records between BOLD
and GenBank. Finally, although sequences for C. limbatus
samples had slightly different barcodes between them, they all
1.8% 7.5%
3.3% 2.8% 5.7%
4.5% 0.9%
7.5% 0.9%
Fig. 3 Relative landings composition (%) of the top six species for each of the three regions (Western, Central, and Northern). The chart at the upper left
shows the overall species composition for the three regions combined.
Mar Biodiv
matched this species in both databases. However, sequences
from C. amblyrhynchoides yielded ambiguous results, and
matched both C. limbatus and C. amblyrhynchoides.
Tax ono mic cl ust erin g
While there were differences in classifications at the family
and order levels, all three trees provided similar outcomes in
terms of taxonomic clustering. In all trees, specimens from
database sequence matches that could have been either
C. limbatus or C. amblyrhynchoides were all assigned to one
cluster and were not distinguishable. Some P. randalli and
C. macrostoma samples clustered as one species, while one
C. macrostoma sample stood out as a separate species. Results
based on the NJ tree are illustrated in Appendix B.
This fishery-dependent assessment is the first comprehensive
study on shark species found in southern Gulf waters, and it
has enabled the development of an updated regional checklist
of species by providing an overview of the composition of
shark landings at various sites in the UAE. The study greatly
improves the current knowledge regarding species richness,
relative abundance, and distribution of sharks exploited by the
UAE fishery. Although data are still incomplete, and in some
cases insufficient to draw conclusions regarding the abun-
dance and conservation status of each species in the region,
our results indicate that sharks are an important component of
the marine biodiversity of the Gulf. Here, we discuss the
various results from this study and their implications for shark
conservation in the region, and then offer some recommenda-
tions for further study and management measures.
Species diversity and occurrence
The latest annotated checklist confirmed the presence of 26
shark species in the Gulf (Moore et al. 2012b). The present
study has raised this number to 31 and has validated the
occurrence of species such as C. griseum,C. plumbeus,
N. ferrugineus,andC. falciformis that had been previously
mentioned in the literature but with no supporting evidence
such as photographs or samples (Gubanov and Schleib 1980;
Randall 1986;Bishop2003; Compagno et al. 2005). Since the
number of species encountered rose very little after the first
year of study, it is likely that the actual species composition of
sharks in the region, along with the abundant species found in
UAE Gulf waters, have been accurately documented. How-
ever, it is important to note that these surveys may have
underestimated protected, discarded, rare, or even migratory
species. For instance, while only one whale shark, R. typus,
was recorded in this study, that species has historically been
reported in the Gulf, and more recently, large aggregations
have been documented in the offshore waters of Qatar (Rob-
inson et al. 2013). While incidental bycatch of this species
may still occur, they presumably go unreported or catches
may not be retained since they are protected in the UAE
(Jabado et al. 2014). Similarly, reports of C. melanopterus
from the Gulf are widespread, but few specimens have been
confirmed (Gubanov and Schleib 1980;Bishop2003). Moore
et al. (2011) suggested that this species may have been re-
placed by C. leiodon in shallow water habitats of the Gulf.
However, in the UAE, C. melanopterus is common around
many coastal and offshore islands (RWJ, personal observa-
tion) where fishing is prohibited, and the low number of
sharks (n=38) recorded in this study may not reflect their
abundance. Furthermore, as noted by Jabado et al. (2014),
most carpet shark species with low market value, such as
C. arabicum and S. fasciatum, are generally discarded at sea
and thus are presumably not accurately represented in land-
ings. This could also be due to fishing practices and the
positioning of fishing gear, which may preclude the capture
of demersal or bottom-associated species such as these. Final-
ly, it is possible that other, less abundant species or seasonal
migrants would have been documented if more frequent sam-
pling had been undertaken or if the study had focused on
certain remote areas where targeted shark fisheries were pres-
ent. For instance, the C. taurus in this study was reported
opportunistically when a fisherman showed the project inves-
tigator pictures of his catches on an offshore island in Abu
Dhabi (Jabado et al. 2013).
The presence of species documented in this study that had
not been previously reported from southern Gulf waters, in-
cluding C. amblyrhynchos and G. cuvier, may indicate that
they are either less abundant or migratory. For instance, the
C. leiodon specimens were recorded only in November and
December, suggesting that this species may be present in these
waters during limited times of the year (Moore et al. 2013). To
date, however, the only evidence of the occurrence of
N. acutidens was from a photograph in Saudi Arabia (Basson
et al. 1977). The collection of 41 individuals during the
present study suggests that this species is more common than
previously thought. Finally, the actual number of shark spe-
cies in the Gulf may be even higher, as the sighting of a
thresher shark, Alopias sp., was reported by a diver at an
offshore wreck in Dubai. It was recognized based on its
sharkappearance and its elongated tail (David Holdman,
pers. comm.), a characteristic feature in this family of sharks
(Compagno et al. 2005). While verification of this sighting is
not possible, it is important to note that thresher sharks have
been reported in the literature, and the remains of four caudal
vertebrae belonging to threshers have been documented at
archeological sites in Abu Dhabi (Beech 2004b). Furthermore,
both the pelagic thresher, Alopias pelagicus (Nakamura,
Mar Biodiv
1935), and the big eye thresher, A. superciliosus (Lowe,
1841), are present in Omani waters (Henderson et al. 2007).
Considering that the Gulf is regarded as a highly stressful
environment for many species, the total number of shark
species recorded from this study is high. Indeed, studies from
the Red Sea, an enclosed body of water considered a marine
biodiversity hotspot, have confirmed only 29 species of sharks
(Golani and Bogorodsky 2010; Spaet et al. 2011). Surveys
conducted in Omani waters have documented 36 shark spe-
cies from the Arabian Sea, while 34 species have been report-
ed in the Maldives (Anderson and Ahmed 1993; Henderson
and Reeve 2011). However, compared with other countries in
the broader Indian Ocean region such as India, which has
documented 66 shark species, and Sri Lanka with 61 species,
the species richness in the Gulf is significantly lower (Joseph
1999;Rajeetal.2002;Herath2012). This may be due to a
variety of reasons, including the diversity of fishing gear used
in other countries as well as exploited habitats. Indeed, in
countries that fish in the Gulf, operations are characterized
by artisanal fisheries limited to wooden dhows and fiberglass
dories using traditional gear (Carpenter et al. 1997), whereas
other countries in the region utilize a diversity of fishing
vessels that operate with a variety of gear at different depths
(Joseph 1999).
The limited bathymetry of the Gulf likely precludes habi-
tation by deepwater species such as the bramble shark,
Echinorhinus brucus (Bonnaterre, 1788), that has been docu-
mented in Oman, or even small species favoring deep waters,
such as the bigeye hound shark, Iago omanensis (Norman,
1939), that are commonly found in the Arabian Sea (Hender-
son et al. 2007; Javadzadeh et al. 2010; Henderson and Reeve
2011). The global deepwater chondrichthyan fauna, for exam-
ple, is highly biodiverse yet remains largely undocumented
(Kyne and Simpfendorfer 2007). Several studies have now
indicated that shark species richness can be affected by both
bottom-water temperature and depth, with distinctive fauna
characterized by spatial distribution of species (Menni et al.
2010; Guisande et al. 2013). Therefore, since the deepest
waters in the Gulf are close to the Strait of Hormuz, where
there is a lack of fisheries data and research, it is possible that
shark species not previously recorded for this basin may be
present, and that these could be subdivided based on different
variables such as depth and temperature.
Carcharhinidae was the dominant species (95.5 %) among
landings investigated in this study. It has been shown that this
family is very important in both commercial and artisanal
fisheries across the world, and species within the family
dominate shark landings in many tropical areas (Castillo-
Geniz et al. 1998;Compagnoetal.2005; Henderson et al.
2007;White2007; Last and Stevens 2009). The most abun-
dant species recorded in this study, C. sorrah and R. acutus,
are also widespread regionally, dominating landings in areas
where they occur (Krishnamoorthi and Jagadis 1986;
Anderson and Ahmed 1993;Bonfil2001; Capapé et al.
2006; Henderson et al. 2007;FAO2009;LastandStevens
2009; Moore et al. 2012a).There are few available historical
records of C. limbatus in the Gulf region, and it is not fre-
quently found in landings from Kuwait, Qatar, or Bahrain
(Moore et al. 2012a; Moore and Peirce 2013). However, it
represents one of the eight most abundant species in Omani
landings (Henderson et al. 2007), which is consistent with
findings in this study. Loxodon macrorhinus has been docu-
mented in Oman landings as the third most abundant, and in
Maldives, where it represented 70 % of sharks caught based
on a research survey (Anderson and Ahmed 1993). During the
first year of their study, Henderson et al. (2007) noted that
L. macrorhinus was absent from landings in Al Batinah, Al
Wusta, and Musandam, but subsequently became the most
abundant landed species in Musandam. In our study, individ-
uals were recorded from all sites and were most common in
RAK (comprising 62.8 % of landings), which is situated
adjacent to the Musandam Peninsula. However, they were
rare in Abu Dhabi (n = 8), and it is likely that the high number
of records from Abu Dhabi (155 individuals) reported by
Moore et al. (2012a), which lack information regarding their
place of capture, reflect the transport of sharks overland from
other areas in the UAE or Oman for sale at the market
(unpublished data). Reports of C. dussumieri suggest that this
species is widespread and abundant in the Gulf, especially in
Kuwait and Iran, although it is not frequently recorded in
Bahraini or Omani landings (Blegvad and Loppenthin 1944;
Basson et al. 1977; Gubanov and Schleib 1980; Henderson
et al. 2007;FAO2009; Moore et al. 2012a; Moore and Peirce
2013). Mustelus mosis has been reported in various publica-
tions (Blegvad and Loppenthin 1944; Basson et al. 1977;
Gubanov and Schleib 1980), but information regarding its
abundance remains scarce. Moore and Peirce (2013)notedit
as the second most abundant species from landings in Bahrain,
and while it was documented in Oman by Henderson et al.
(2007), no details were provided regarding its occurrence.
All species reported from Kuwait, Qatar, and Bahrain
landings were also present in UAE landings (Moore et al.
2012a; Moore and Peirce 2013). The lower number of species
recorded in northwestern Gulf surveys may be a result of the
limited temporal sampling there, which occurred only during
April. Indeed, even in the UAE, some species were recorded
only at specific times of the year, such as C. falciformis in the
autumn months. Furthermore, with the exception of the two
Chiloscyllium species, N. ferrugineus, and R. oligolinx, the
majority of species reported here were also documented in
Omani landings (Henderson and Reeve 2011).
Spatial and seasonal distribution
A total of 26 species of sharks were recorded in Sharjah, while
only 19 species were recorded in Abu Dhabi, and these two
Mar Biodiv
sites had the lowest species overlap. While these differences
are likely not due to fishing methods utilized, since similar
gear is used across the country, they may be explained by the
variability in fishing grounds used by fishermen in these two
emirates and differences in habitat and environmental condi-
tions in the two areas. Although Abu Dhabi waters include
some offshore islands with deeper waters, most of the western
inshore is characterized by shallow embayments with higher
water temperatures and salinities (EAD 2011). On the other
hand, fishermen in Sharjah largely utilize offshore and deeper
waters towards the northeastern UAE region, which are
supplied with oceanic water inflowing from the Arabian
Sea (Price 1993). Studies have shown that the richest areas
for fish fauna within the Gulf are closer to the Strait of
Hormuz, where waters are deeper (Price 1993). The simi-
larities in species recorded for Sharjah, RAK, and even
Dubai likely reflect the use of similar fishing grounds.
Landings of M. mosis, on the other hand, were notable in
RAK but less frequent in Dubai and Sharjah, potentially
indicating a difference in species behavior.
While there were some seasonal variations in the numberof
species caught, the overall dominant species did not change
throughout the sampling period. However, there was a shift in
seasonal dominance between C. sorrah and R. acutus,where
C. sorrah was more common during spring and summer,
while R. acutus was more abundant in autumn and winter
landings. All other species were caught in lower numbers
during the summer, which was also the season that yielded
the lowest number of landed species overall, comprising only
17.8 % of total landings. Studies on demersal teleost fish
species in the Gulf show patterns of distribution and abun-
dance that vary seasonally and among habitat types (Basson
et al. 1977; Shallard and Associates 2003). Grandcourt (2012)
suggested that this was likely due to higher water temperatures
during the summer and the lower volume of fishing activity at
that time of the year. In fact, it is believed that the reduced
abundance of reef fish during the summer is a result of the
movement of species to deeper and cooler waters (Shallard
and Associates 2003). Some studies have shown that the most
common species of sharks can change seasonally (Bizzarro
et al. 2009). Data from the artisanal shark fishery in Mexico
showed landings that were highly seasonal and that varied
among regions, which was attributed to the migratory behav-
ior of various species of sharks (Castillo-Geniz et al. 1998).
Similarly, landings in Oman showed marked differences
among seasons and across survey sites, also believed to be a
result of the migration patterns of different shark species
(Henderson et al. 2008). Lastly, seasonal differences in
landings may be due to variations in relative abundance
of shark species in local waters. Indeed, as fishermen
were found to be highly opportunistic, and as most areas
within UAE waters have been utilized for fishing, the
species composition of landings across seasons and
locations likely are a true reflection of local relative
abundance (Jabado et al. 2014).
With the exception of C. limbatus, the dominant species in
the UAE are relatively small sharks, measuring less than
1,500 mm L
, that commonly form large schools in inshore
waters (Compagno et al. 2005; Last and Stevens 2009). While
little is known about the behavior of M. mosis,itmostlikely
forms groups in inshore areas in a similar fashion to other
species of triakids known to be abundant in coastal waters
(Compagno et al. 2005). Likewise, C. limbatus, a larger shark
reaching over 2,500 mm L
, is known to prefer inshore areas
and is commonly found in large surface schools (Compagno
et al. 2005). This aggregating behavior and preference for
inshore waters may explain the particularly high abundance
of these species in landings. Similarly, the market dominance
of predominantly small-bodied sharks from a limited number
of species has been recorded in other areas. Data from Oman
have reported that the dominance of eight species among
landings (Henderson et al. 2007). Five species represented
64 % of landings in the northeastern Gulf (Moore et al.
2012a); three species were dominant in Iran (FAO 2009); 12
species were most abundant in Sri Lankan catches (Herath
specimens recorded in Chinese markets (Lam and Sadovy
de Mitcheson 2011). In this study, while some species of
large-bodied sharks were found in landings, they were largely
either immature specimens (unpublished data), such as
C. limbatus, or species that did not contribute substantially
to landings, such as C. brevipinna and S. mokarran.
While little information is available on whether larger
sharks were more common at one time, fishermen have stated
that the size of sharks in the Gulf has greatly diminished
(Jabado et al. 2014). As such, it is possible that many larger
species have been overfished to some extent, and that the
fishery is now reliant on smaller sharks that are dominant in
landings. It is important to note that individual species may
have different levels of susceptibility or resilience to exploi-
tation (Stevens et al. 2000; Bonfil 2001). Small-bodied
carcharhinids such as R. acutus tend to grow fast, mature
early, have short life spans, and display aseasonal reproductive
cycles (Wourms 1977; Stevens and McLoughlin 1991). On
the other hand, larger sharks such as C. brevipinna mature
much later and exhibit slower growth rates, while typically
displaying seasonal breeding cycles and producing annual,
biennial, or triennial litters (Wourms 1977; Last and Stevens
2009). Thus the overall lifehistory traits ofsmall shark species
generally lead to higher biological productivity, making them
less susceptible to fishing pressure, which may explain their
dominance at various markets. Musick et al. (1993) noted that
overexploitation of large sharks in areas off southeastern
Africa and the northwest Atlantic could have led to the pro-
liferation of small-bodied sharks. A declining trend in the
number of large sharks and a shift in efforts towards smaller
Mar Biodiv
individuals have also been documented in Mexico, China, and
Madagascar, where species composition of landings for the
whole area has been affected (McVean et al. 2006;Bizzarro
et al. 2009;LamandSadovydeMitcheson2011). Henderson
et al. (2007) documented such a shift in the Omani shark
fishery, where in just a few years, larger sharks such as
C. limbatus and S. lewini were displaced by the smaller
L. macrorhinus and C. macloti.
A change in species composition or size of fished sharks
could have serious implications for the sustainability of a
fishery (Stevens et al. 2000). Furthermore, population studies
of coastal shark species have indicated that even a slight
increase in juvenile mortality can greatly impair the sustain-
ability of coastal shark fisheries (Cortes 1998). It is well
known that anthropogenic impacts such as overfishing and
habitat degradation have altered populations of sharks around
the world (Stevens et al. 2000). The risk to many species is
also believed to be depth-related, where species occupying
shallower waters are more accessible to fishing activities
(Dulvy et al. 2014). Considering the relatively small size and
shallow depth characteristics of the Gulf, as well as the in-
creasing anthropogenic disturbances that this entire basin is
facing, it is important to monitor shark catches in the UAE in
order to document changes in species and size composition of
shark landings.
Species identification
A complete and reliable taxonomic account of shark species is
the most crucial, albeit challenging, aspect of fishery sam-
pling, and is an integral component of effective fishery man-
agement, as it allows identification of species richness and
diversity (White and Last 2012). In many instances, molecular
methods such as the use of the COI gene sequence have
become important identification tools for distinguishing be-
tween closely related species (White and Last 2012). In most
cases here, morphologically identified species were congru-
ently matched in the BOLD and GenBank COI databases and
conspecific species clustered together in the NJ analysis.
However, some questions about specimen identification
The inability to assign C. arabicum to a species in either
database is due to the fact that a barcode for this species is not
available for comparison. Similarly, the lack of a match for
R. oligolinx in GenBank also indicates a lack of sequences for
this species within the database. The clustering of P. randalli
and C. macrostoma sequences that also matched P. tengi
(Chen, 1963), a species that has not been recorded from the
western Indian Ocean (Compagno et al. 2005), may be due to
a variety of reasons, including the possibility that these species
share haplotypes, or that there was misidentification in the
field, mislabeling errors for the samples, or misidentification
of species associated with COI sequences in the databases
(White and Last 2012).
The success of barcoding is dependent upon low levels of
sequence variation within species and much higher levels
between species (Holmes et al. 2009). As such, some closely
related species may not be easily identifiable despite their
morphological differences. In our study, the C. limbatus and
C. amblyrhynchoides species pair could not be convincingly
differentiated by barcoding. Ward et al. (2008)reportedlow
COI sequence divergence and low bootstrap support for these
species, and Moore et al. (2011)statedthattheCOIgenewas
barely distinguishable between them. Similar outcomes were
also reported for the closely related species C. plumbeus and
C. altimus (Springer, 1950), leading to the conclusion that the
COI barcode may not be suitable for discriminating among
some closely related shark species, and that an additional
marker with a higher rate of evolution would be necessary
(Ward et al. 2008).
It has been recommended that developing a voucher col-
lection is a necessity when undertaking genetic analysis in
order to resolve questions about specimen identification
(Ward et al. 2005). A collection could not be started in this
study because of limited resources and lack of storage facili-
ties necessary when dealing with large animals such as sharks.
Only one study has focused on developing a specimen and
barcode collection for fish species in the Gulf, which included
two shark species, C. macrostoma and M. mosis (Asgharian
et al. 2011). Therefore, it seems that to better understand the
evolution of species within the Gulf, a centralized facility
would be warranted.
Considerations for shark conservation
A number of species considered to be of global conservation
concern were recorded in this study, including C. limbatus,
C. dussumieri,C. falciformis,C. plumbeus,S. lewini, and
S. mokarran, which are listed either as threatened or Near
Threatened on the IUCN Red List (IUCN 2012). However,
because IUCN assessments generally lack information from
the Gulf, accurate data obtained locally are needed to deter-
mine which species here are most threatened. While data
collected in this study are not a clear indication of the status
of shark stocks in the UAE, they do provide a baseline that
should prove beneficial for effective future monitoring and
sustainable exploitation of targeted shark stocks. Results sug-
gest that there may be a depletion of larger shark species in
these waters, where there is a clear lack of species-specific
regional life history data and quantitative mortality
While some laws for shark management already exist in the
UAE, they should be reexamined in light of the data gathered
from this study and before unmonitored catches further com-
promise the recovery of already-depleted stocks in the Gulf.
Mar Biodiv
Globally, the conservation of sharks has been confounded by
delayed responses regarding fishery restrictions, typically
resulting in the implementation of management strategies
following overexploitation of targeted shark populations (Ste-
vens et al. 2000). Although there is no baseline information
with which to compare the results from this study, all of the
data here and from interviews with Emirati fishermen indicate
that there is a high level of pressure on shark populations in
UAE Gulf waters (Jabado et al. 2014). In view of the life
history traits and the possible detrimental impacts of fishing
on many shark species, a precautionary approach to managing
these resources is warranted.
Acknowledgments We are grateful for the grant from the United Arab
Emirates University to Rima W. Jabado that supported this project. The
genetic analysis of the samples was supported by the Save Our Seas
Foundation. We are grateful to Kimberley Atwater for the laboratory
genetic work and to the volunteers who participated in the field surveys,
without whom this study would not have been possible.
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... The ongoing changing aspects of these two processes cause ongoing difficulties for those with conservation interests. Studies revealed that the Arabian Seas Region plays an important role in the global landings of sharks and rays [27,28]. The authors state that observed landings varied among regions and across seasons, results clearly showed that shark landings were dominated by small-sized specimens, which is indicative of overexploitation. ...
... Besides the political will and lack of regulatory enforcement, the deficiency of robust scientific data is impeding progress towards wellmanaged shark fisheries. Some developed countries have carried out wide-ranging research, but fewer studies have been performed in developing nations, often with higher shark biodiversity, highlighted by non-effective fisheries management and a lack in policy enforcement means [27,32,46,47]. ...
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Challenges that relate to shark conservation may well be a combination of the intersection of people's livelihoods and the ineffectiveness of management strategies. Given the current protection initiatives as well as the implementation of tighter laws restricting hunting and trade, shark conservation is still recognized as a major environmental challenge. The United Arab Emirates (U.A.E.) is used as an export hub and is one of the primary exporters of shark fins to Hong Kong, with a large proportion of fins traded to be from species at high risk of global extinction. The present-day management of shark fisheries also shows shortcomings concerning lawfulness, specifically those relating to regulatory compliance, fishing techniques, and control of finning occurrences. These concerns are not unique to the U.A.E. but emphasize the fact that there are far-reaching problems related to shark conservation. Even in a milieu of strengthened conservation measures and revised legislature, existing information on the effectiveness of a shark finning ban may still be misleading when viewed in the light of over-exploitation and global species abundance. It is therefore important that proper management must be implemented at the inception of shark fisheries. For the U.A.E., this has not always been the case. Instead, the trend was one of limited control and lack of compliance, unfortunately, resulting in a rapid decline in shark abundance, to the point where sharks struggle to recover. This paper focuses on the importance of the species, reviews the current monitoring framework, and seeks to enhance shark protection.
... Carcharhinidae was the dominant shark family in terms of species diversity and abundance in catch landings. Several studies have demonstrated that the family Carcharhinidae is prevalent in artisanal elasmobranch fisheries, with certain species within this family dominating shark landings in the sub-Saharan African region (Robinson and Sauer, 2013;Kiilu et al., 2019), the Arabian Gulf (Jabado et al., 2014), Red Sea (Spaet and Berumen, 2015), and in North America (Beerkircher et al., 2002;Bizzarro et al., 2009a,b,c;Cartamil et al., 2011). The most abundant species documented in this study, comprising Prionace glauca, Isurus oxyrinchus, and Carcharhinus brevipinna, are widespread in the sub-Saharan Africa region and dominate the landings in maritime countries where they occur (Temple et al., 2019). ...
... In contrast to studies in Sonora, Mexico (Bizzarro et al., 2009a,b,c) and in the Arabian region (Henderson et al., 2007), seasonal variations in the number of shark and ray species (species richness) in this study was not evident. However, the abundance of shark and ray landings varied seasonally, which is consistent with studies in the Arabian Gulf (Jabado et al., 2014;Spaet and Berumen, 2015). The variations in shark catch between the minor rainy season and dry season may be partially explained by the higher fishing effort in terms of number of fishing trips and distance covered by fishers within the minor rainy season. ...
Despite the fact that elasmobranchs are now targeted in artisanal fisheries in the wake of continuous declines of teleosts in Ghana, data on any aspects of these fisheries are poor. This study aims to document the spatial and temporal variation, and biological composition of elasmobranchs in five key elasmobranch-dominated fishing communities in Western Ghana, which include Adjoa, Axim, Busua, Dixcove and Shama. A total of 2157 elasmobranchs comprising 1414 sharks and 743 rays, belonging to 34 species in 15 families, were recorded over the course of 9 months. Prionace glauca (81.2%) and Raja parva (29.3%) were the dominant shark and ray species, respectively. Shama had the highest mean shark catch (33.3 ± S.D 29.7), followed by Dixcove (19.1 ± 14.7) and Axim (18.2 ± 12.4). However, Axim exhibited the greatest mean ray catch (25.8 ± 10.6), followed by Adjoa (10.9 ± 3.8) and Busua (9.6 ± 5.4). The greatest relative catch and species richness for all the sites was documented in the minor rainy season (August to November). Sexual segregation was typical among most of the common elasmobranch species landed. This study serves as a baseline for monitoring future changes in the artisanal shark and ray fisheries in Western Ghana.
... Several studies have focused on understanding the impact of UAE fisheries on species over the past decade (e.g. Jabado et al., 2015b;Jabado et al., 2016), however, the understanding of the potential role that MPAs can play in advancing the conservation of elasmobranchs in the Arabian Gulf region is limited. Within this context, Sir Bu Nair MPA fulfils four of the five criteria associated with effective MPAs (Edgar et al., 2014) by essentially being no take, relatively well enforced (the island is a police outpost), old (>20 years old), isolated (at least 65 km offshore from the closest mainland point), but missing an important feature for shark conservation, large (>100 km 2 ). ...
... Yet, it is improbable that the SBN MPA would have had low abundances of elasmobranchs prior to its establishment in 2000. Interviews with fishers in the UAE have consistently pointed to this location as being one of the hotspots for many elasmobranch species, including sawfishes (family Pristidae) which are one of the most threatened groups of marine fish around the world (Jabado et al., 2015a(Jabado et al., , 2015bJabado et al., 2017). Therefore, it is likely that the low abundances recorded here are a true reflection of the present state of declining elasmobranch stocks in the region as previously reported (Jabado et al., 2018a). ...
Marine Protected Areas (MPAs) are increasingly advocated for the protection of key functional groups like elasmobranchs (sharks and rays). However, substantial uncertainty remains regarding which species can benefit from MPAs, crucial information to support policy and management plans. Using Baited Remote Underwater Video Surveys (BRUVS), a study was conducted on Sir Bu Nair Island in the United Arab Emirates encompassing a range of depths and habitat types within the MPA borders. A total of 96 deployments with 117 video hours recorded were analysed to assess the diversity, relative abundance and habitat associations of elasmobranchs. Surveys recorded 40 elasmobranchs including two species of sharks and seven species of rays. Overall, catch per unit effort for elasmobranchs was slightly higher overall, lower for sharks, and higher for rays compared to a similar study using BRUVS across United Arab Emirates waters. Two reef-associated species in early life stages, blacktip reef shark (Carcharhinus melanopterus) and Halavi guitarfish (Glaucostegus halavi) listed as Near Threatened and Critically Endangered on the IUCN Red List of Threatened Species respectively showed the highest frequency of occurrence of species representing 44.4% of all sightings. These results show the value of this MPA in protecting critical habitats for elasmobranchs while suggesting its limitation in protecting adult life stages and other elasmobranchs with wider ranging movements that are likely threatened by fishing in waters adjacent to the MPA. This study provides critical information to support the development of a Sir Bu Nair management plan and highlights further research needs around the island. Finally, it reinforces the need of additional management measures to protect and promote the recovery of elasmobranchs in the United Arab Emirates and broader Arabian Gulf.
... The range of Scoliodon has recently included the Persian Gulf and parts of East Africa [7,9]. Bishop [105] and Sivasubramanian and Ibrahim [106] recorded it from off Kuwait and Qatar, respectively, but more recent comprehensive surveys of these locations, as well as of Bahrain and the United Arab Emirates, did not record any S. laticaudus in fisheries landings [107][108][109]. Amojil et al. [110] included this species as only possibly occurring in the Persian Gulf due to the lack of verifiable records. ...
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Previous examination of the mitochondrial NADH2 gene and morphological characteristics led to the resurrection of Scoliodon macrorhynchos as a second valid species in the genus, in addition to S. laticaudus. This study applied an integrated taxonomic approach to revisit the classification of the genus Scoliodon based on new materials from the Malaysian Peninsula, Malaysian Borneo and Eastern Bay of Bengal. Mitochondrial DNA data suggested the possibility of three species of Scoliodon in the Indo-West Pacific, while the nuclear DNA data showed partially concordant results with a monophyletic clade of S. macrorhynchos and paraphyletic clades of S. laticaudus and S. cf. laticaudus from the Malacca Strait. Morphological, meristic and dental characteristics overlapped between the three putative species. Collective molecular and morphological evidence suggested that the differences that exist among the non-sympatric species of Scoliodon are consistent with isolation by distance, and Scoliodon macrorhynchos remains as a valid species, while S. cf. laticaudus is assigned as S. laticaudus. The Malacca Strait acts as a spatial delineator in separating the Pacific S. macrorhynchos (including South China Sea) from the Northern Indian Ocean S. laticaudus. Future taxonomic work should focus on clarifying the taxonomic status of Scoliodon from the Indonesian waters.
... This situation is worse, particularly in developing countries, where adequate management tools and political will lack, and widespread illicit fishing of juvenile and brood fishes are the common characteristics of the fisheries (Froese, 2004;Spaet et al., 2012;Jabado and Spaet, 2017). Given this, the formulation of effective management plans that ensure relevant stakeholders' participation is urgent to promote ecosystem conservation and achieve optimal yields to sustain livelihoods and food supply (Jabado et al., 2015). Again, an effective management plan includes various management tools, such as total allowable catch (TACs), setting minimum and maximum size limits of fish for catches, regulating the usage and nature of the fisheries selectivity, and banning fishing in some areas or seasons (Alam et al., 2021). ...
The small-scale fisheries in the northern Bay of Bengal coast of Bangladesh have been suffering due to an uncontrolled expansion of the fishing effort. Given this, it is important for all stakeholders to understand the current stocks’ status and their response to the present degree of removal. This study used two different methodological approaches to assess six commercially important fish species’ stock status from this coast with fisheries representative length-frequency data: a length-based Bayesian biomass estimation method (LBB) for relative fishing mortality and stock biomass, and Froese’s length-based indicators (LBIs) for the sustainability of the fisheries. The present findings revealed that the biomass of Bregmaceros mcclellandi, Escualosa thoracata, Ilisha filigera, Johnius belangerii and Coilia dussumieri was below the target reference points (B/Bmsy < 1 in LBB and SB < SBtarget in LBIs), suggesting overfished status of those fisheries. The biomass of Megalaspis cordyla, on the other hand, was above the threshold level (B/Bmsy=1.1 in LBB & SB > 0.4SBtarget in LBIs). Depending on the outputs, this study recommended not to catch fish with lengths equal or smaller than the length at first sexual maturity to avoid growth overfishing, exclude the mega-spawners (length > Lopt+10%) from the catch for preventing recruitment overfishing, and bring the fishing mortality back to the sustainable level (F=M) by reducing the existing number of boats to its half for fisheries long-term survivability.
... Therefore, 26% of the species of Phoreiobothrium belong to the southern waters of Iran. Given the fact that the members of Phoreiobothrium are highly host specific, so that 17 valid species have their own host species and only two species, namely P. exceptum and P. pectinatum, have a same type host, i.e., Sphyrna zygaena (L.), (see [1]), and since the species of Phoreiobothrium infect the two shark families Carcharhinidae and Sphyrnidae found abundantly off southern Iran [13][14][15], it is expected that more species occur in the Persian Gulf and the Gulf of Iran. ...
PurposeThe aim of this work was the morphological study of the onchoproteocephalidean cestodes from two shark species of the Persian Gulf.Methods Several specimens of Rhizoprionodon oligolinx, as well as of Carcharhinus dussumieri, were collected from the Persian Gulf, and the isolated cestodes from them were studied morphologically by light and scanning electron microscopy.ResultsPhoreiobothrium sarahae n. sp. and Phoreiobothrium iraniense n. sp. were isolated, respectively, from Rhizoprionodon oligolinx Springer and Carcharhinus dussumieri (Müller & Henle). Both species are quite distinct from their congeners, except for P. sorrahcola Masoumi Ganjgah & Haseli, 2020, in the distribution of the vitelline follicles (i.e., having more than two columns of vitelline follicles in each lateral band in the proglottids) and are distinguished from each other based on measurement, e.g., by the length of the cephalic peduncle, the width of the scolex at the level of hooks, and some measures related to the hooks. Phoreiobothrium iraniense n. sp. most closely resembles P. sorrahcola, earlier described from C. sorrah (Müller & Henle) from the Persian Gulf, with which it has an extensive overlap in the ranges of measurements and morphology. Nonetheless, it differs from P. sorrahcola in the length of the cephalic peduncle and possessing, rather than lacking, the gladiate spinitriches on the proximal bothridial surfaces.Conclusion Along with the description of the two new species increasing the number of members of the genus in the Iranian coastal waters from three to five, for the first time a variation in distribution of the vitelline follicles is reported for Phoreiobothrium in this paper.
... Significant knowledge of the species assemblages occurring in this region has accrued in the past decade in large part through reviews of the grey literature and field surveys investigating fish landings (e.g., Henderson et al. 2007;Moore et al. 2012;Spaet et al. 2012;Jabado et al. 2015a, c;Spaet and Berumen 2015;Jabado and Spaet 2017). These works have emphasised the considerable diversity of sharks and rays targeted by the regional fisheries (Jabado et al. 2015b) but also raise severe concerns about the sustainability of fishing pressure, particularly considering the vulnerability of these fishes to exploitation. Using the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species categories and criteria, a recent regional assessment suggested that this region comprises some of the world's most threatened populations of chondrichthyans (over 50% of species were considered Critically Endangered, Endangered, and Vulnerable), and identified overfishing as their primary threat followed by habitat loss and degradation (Jabado et al. 2017). ...
A total of 138 chondrichthyan species—11% of the world’s known species—are currently known to occur in the waters surrounding the Arabian Peninsula, including 68 sharks from 22 families and 41 genera, 68 rays from 14 families and 33 genera, and two chimaeras from one family and one genus. Of these, 29 species are endemic to the region. The chondrichthyan species assemblage in the Arabian Sea and its adjacent waters do not reflect global shark and ray diversity, with some orders (e.g., Carcharhiniformes, Myliobatiformes, and Rhinopristiformes) very well represented, other taxa (e.g., families Squalidae and Rajidae) poorly represented, and Squatiniformes (angel sharks) entirely absent. Almost all chondrichthyan species found in these waters are heavily impacted by artisanal and industrial fisheries as well as coastal development. In fact, a recent regional IUCN Red List of Threatened Species assessment indicated that over half of them were threatened with extinction. These include species listed on the appendices of both the Convention on the International Trade of Endangered Species of Flora and Fauna and the Convention on the Conservation of Migratory Species of Wild Animals. The lack of overall fisheries management or enforcement of existing measures is a major issue and actions need to be immediately taken to ensure the long-term survival of most chondrichthyan species in the Arabian seas.
... This situation is worse, particularly in developing countries where proper management tools and political will lack and pervasive illegal fishing of juvenile and brood fishes is the fisheries' governing features [2][3][4]. This worst-case scenario of the stocks provides the impetus for articulating effective management tools, focusing on all concerned stakeholders' participation to promote conservation of the ecosystems and achieve the optimum yields to sustain the livelihoods and sustainable food supply [4,5]. Again, an effective management plan encompasses various management tools, including effort control, minimum mesh size regulations for nets, and maximum allowable catch limits [6,7]. ...
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The anadromous tropical Hilsa shad formed the largest single-species fishery in Bangladesh, making the highest contribution to the country’s total fish production (14%) and nearly 83% of the global Hilsa catch in 2018. However, increased fishing pressure made the fishery vulnerable, and hence, information on the stock condition and its response to the current degree of removal is essential to explore the future potential for sustainable exploitation. This study carried out a rigorous assessment based on three different methodological approaches (traditional length-frequency based stock assessment method for fishing mortality and exploitation, Froese’s length-based indicators for fishing sustainability, and a surplus production-based Monte Carlo method-CMSY, for fisheries reference points estimation) for the best possible estimates of the Hilsa stock status in the water of Bangladesh. The present findings revealed that the stock is likely to be overfished due to over-exploitation. Depending on the outputs, this study recommended a lower length limit for the catch (> 33 cm), distinguished a selectivity pattern (mesh size limit ≥ 8 cm), and proposed a yearly landing limit (within the range of 263,000–315,000 tons) for the sustainable management of the Hilsa fishery in Bangladesh. Keywords: Hilsa fishery; stock assessment; three different methodological approaches; over-exploitation and depleted stock biomass; management recommendations
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The sampling of 22 specimens of Rhizoprionodon oligolinx Springer from the Persian Gulf made possible the description of three new species of Anthobothrium van Beneden, 1850. Anthobothrium parimae sp. nov. is different from its congeners, except for A. altavelae Neifar, Euzet and Ben Hassine, 2002, A. lyndoni Ruhnke and Caira, 2009, and A. lesteri Williams, Burt and Caira, 2004, in the total length. It differs from A. altavelae in the number of the proglottids; from A. lyndoni in the length of the mature proglottids; and from A. lesteri Williams, Burt and Caira, 2004 in possessing one hemicircular band, rather than two circular bands, of musculature in its bothridia. The other two new species, being the smallest in size within the genus, most closely resemble each other but differ in the position of the genital pore in the proglottid, the number of post-vaginal testes, the number of the ventral and dorsal columns of vitelline follicles in each lateral band, and the distribution of the gladiate spinitriches on the strobila. These three new species are the only “tetraphyllidean” species reported to date from the southern waters of Iran. In addition, for the first time, more than two congeners belonging to Anthobothrium are reported from the same host species sympatrically and simultaneously. The morphological variation within this genus is also discussed.
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The bull shark (Carcharhinus leucas Valenciennes, 1839) is a large, primarily coastally distributed shark famous for its ability to penetrate far into freshwater bodies in tropical, subtropical, and warm-temperate climates. It is a cosmopolitan species with a geographical range that includes the coastlines of all major ocean basins (Atlantic Ocean, Indian Ocean, Pacific Ocean). As a consequence, freshwater occurrences of C. leucas are possible everywhere inside its geographic range. Carcharhinus leucas is a fully euryhaline, amphidromous species and possibly the widest-ranging of all freshwater tolerating elasmobranchs. This species is found not only in river systems with sea access that are not interrupted by human impediments but in hypersaline lakes as well. Rivers and estuaries are believed to be important nursery grounds for C. leucas, as suggested by observations of pregnant females in estuaries and neonates with umbilical scars in rivers and river mouths. Due to the physical capability of this species to enter riverine systems, the documentation of its occurrence in fresh and brackish water is essential for future conservation plans, fishery inspections, and scientific studies that focus on the link between low salinity habitats, shark nurseries, and feeding areas. The author’s review of the available literature on C. leucas revealed the absence of a comprehensive overview of fresh and brackish water localities (rivers and associated lakes, estuaries) with C. leucas records. The purpose of this literature review is to provide a global list of rivers, river systems, lakes, estuaries, and lagoons with records and reports of this species, including a link to the used references as a base for regional, national, and international conservation strategies. Therefore, the objective of this work is to present lists of fresh and brackish water habitats with records of C. leucas as the result of an extensive literature review and analysis of databases. This survey also took into account estuaries and lagoons, regarding their function as important nursery grounds for C. leucas. The analysis of references included is not only from the scientific literature, but also includes semi-scientific references and the common press if reliable. The result of 415 global fresh and brackish water localities with evidence of C. leucas highlights the importance of these habitats for the reproduction of this species. Moreover, gaps in available distribution maps are critically discussed as well as interpretations and conclusions made regarding possible reasons for the distribution range of C. leucas, which can be interpreted as the result of geographic circumstances, but also as a result of the current state of knowledge about the distribution of this species. The results of the examination of available references were used to build a reliable and updated distribution map for C. leucas, which is also presented here.
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The rapid expansion of human activities threatens ocean-wide biodiversity. Numerous marine animal populations have declined, yet it remains unclear whether these trends are symptomatic of a chronic accumulation of global marine extinction risk. We present the first systematic analysis of threat for a globally distributed lineage of 1,041 chondrichthyan fishes-sharks, rays, and chimaeras. We estimate that one-quarter are threatened according to IUCN Red List criteria due to overfishing (targeted and incidental). Large-bodied, shallow-water species are at greatest risk and five out of the seven most threatened families are rays. Overall chondrichthyan extinction risk is substantially higher than for most other vertebrates, and only one-third of species are considered safe. Population depletion has occurred throughout the world's ice-free waters, but is particularly prevalent in the Indo-Pacific Biodiversity Triangle and Mediterranean Sea. Improved management of fisheries and trade is urgently needed to avoid extinctions and promote population recovery.
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Paragaleus randalli n. sp. is described from 14 specimens from the northwestern Indian Ocean and the Arabian Gulf. The new species differs from its congeners by its narrow snout, long mouth, lower anterior teeth mostly oblique-cusped and with well-developed distal cusplets, 165-187 total vertebrae, and colouration. The species has inconspicuous white-edged fins and a pair of narrow dark lines on the underside of its snout.
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The following 12 fish species are recorded for the first time from the Gulf and documented by specimens (or parts thereof) deposited in museum collections: Carcharias taurus, Brachypterois serrulata, Scorpaenopsis venosa, Lepidotrigla faurei, Epinephelus epistictus, Priacanthus blochii, Archamia fucata, Alepes kleinii, Upeneus sundaicus, Monodactylus argenteus, Bryaninops amplus and Sphyraena putnamiae. Specimens were collected in Bahrain, Iran, Kuwait, Saudi Arabia and the United Arab Emir-ates. For each species a set of diagnostic characters is given, which will allow the identification of specimens originating from the Gulf. These new records increase the total number of fish species known from the Gulf to 542.
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The waters of the Gulf are characterized by extreme temperature (11.5–36°C) and salinity (37–50‰) ranges which are likely to at least periodically approach or exceed the tolerance limits of many reef fish species (Coles 1988; Coles and Tarr 1990). The narrow Strait of Hormuz constrains the influx of larvae from adjacent seas which also limits species diversity. Whilst the Gulf is a relatively young sea that originated about 16,000 BP, the sea surface did not reach its current level until around 6,000 BP during the Holocene (Sheppard et al. 1992). The present day fish fauna was thus established by the penetration of species from the Indian Ocean through the Gulf of Oman and Strait of Hormuz (Beech 2004). Its small size, limited habitat types and restricted depth also constrain faunal diversity, which is particularly apparent among the families of reef fishes (Randall 1995; Bishop 2003). Consequently, many major shallow water taxonomic groups that are prevalent at similar latitudes throughout the Indo-Pacific and adjacent waters are completely lacking in the area and there are few endemics, with only 16 species of fishes known to occur uniquely within the Gulf (Coles and Tarr 1990; Randall 1995; Carpenter et al. 1997).
The main purposes are to collate information of the region, to review marine systems and processes in the intertidal and shallow sublittoral parts of the Arabian seas, and to highlight human utilisation and environmental consequences. The first section presents the geological, geographical, climatic and oceanographic background to the area. The second section examines what is known of the region's marine communities, interpreting the relationships between the marine systems and physical conditions for: reefs and coral communities; coral reef fish assemblages; other reef components and processes; seaweeds and seasonality; seagrasses and other dynamic substrates; intertidal areas - mangal associated ecosystems, marshes, sabkha and beaches; and the pelagic system. The next section synthesizes and concludes the biogeographical material and interprets the effects of natural stress on the biota. The final section describes and discusses the human use and management of the region, including fisheries. -after Authors
The first evidence-based checklist of sharks of the Persian (Arabian) Gulf is presented based on appraisal of primary literature and new data, including identifications verified by COI barcoding. Evidence of the occurrence of 26 species in the Gulf is presented, and the possible presence of a further 17 species is discussed. Carcharhinidae is the most species-rich family (16 species) present. The first substantiated Gulf records of the spinner shark Carcharhinus brevipinna, blacktip reef shark C. melanopteruş and scalloped hammerhead Sphyrna lewini are provided, along with a new record of the rarely reported grey nurse shark Carcharias taurus. The diversity of the Gulf's shark fauna, and possible influences on it, are briefly discussed.