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received: 2020-04-14                 DOI 10.19233/ASHN.2020.05
CAPTURE OF A BIGEYE THRESHER SHARK ALOPIAS SUPERCILIOSUS 
(ALOPIIDAE) IN TURKISH WATERS (EASTERN MEDITERRANEAN SEA)
Okan AKYOL & Tevfik CEYHAN
Ege University, Faculty of Fisheries, 35440, Urla, Izmir, Turkey
Christian CAPAPÉ
Laboratoire d’Ichtyologie, Université de Montpellier, case 104, 34095 Montpellier cedex 5, France
e-mail: capape@univ-montp2.fr
ABSTRACT
The present paper reports a new capture of bigeye thresher shark, Alopias superciliosus (Lowe, 1839). To date, 
9 specimens have been recorded in the area, suggesting that a viable population of this type of shark might be 
successfully establishing in the area, but other records are needed to confirm this hypothesis. The paper comments 
on the distribution of the species in the Mediterranean Sea, suggesting that it does not originate from this sea, but 
is probably a migrant species from the eastern tropical Atlantic or from the Indian Ocean.
Key words: Chondrichthyes, Alopiidae, distribution, population, migration
CATTURA DI SQUALO VOLPE OCCHIONE ALOPIAS SUPERCILIOSUS (ALOPIIDAE) IN 
ACQUE DELLA TURCHIA (MEDITERRANEO ORIENTALE)
SINTESI
Il presente documento riporta una nuova cattura di squalo volpe occhione, Alopias superciliosus (Lowe, 
1839). Ad oggi, nove esemplari sono stati registrati nell’area, suggerendo che una popolazione vitale di questa 
specie si stia stabilendo con successo nell’area. Saranno comunque necessarie altre segnalazioni per confer-
mare questa ipotesi. L’articolo commenta la distribuzione delle specie nel Mediterraneo, suggerendo che lo 
squalo volpe occhione non sia originario di questo mare, ma sia probabilmente una specie migratrice arrivata 
all’Atlantico orientale o dall’Oceano Indiano.
Parole chiave: Chondrichthyes, Alopiidae, distribuzione, popolazione, migrazione
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Okan AKYOL et al.: CAPTURE OF A BIGEYE THRESHER SHARK ALOPIAS SUPERCILIOSUS (ALOPIIDAE) IN TURKISH WATERS (EASTERN MEDITERRANEAN SEA), 31–36
INTRODUCTION
The bigeye thresher shark, Alopias superciliosus 
(Lowe, 1840), is a cosmopolitan species widely dis-
tributed in warm temperate waters of the the Atlantic, 
Pacific and Indian Oceans (Compagno, 1984). Off the 
eastern Atlantic coast, A. superciliosus is abundantly 
collected off the eastern side of the Atlantic Ocean 
from Portugal and Madeira to Morocco between 15° 
and 40° N (Quéro, 1984); Moreno & Morón (1992) 
and Fernandez-Carvalho et al. (2011) provided data 
about some traits of its reproductive biology from 
these areas. 
A. superciliosus probably entered the Mediter-
ranean Sea through the Strait of Gibraltar; in the 
Mediterranean, it was first recorded in the Ionian 
Sea following Gruber & Compagno (1981). An 
overview of Mediterranean records reported in 
literature shows that at least 40 specimens have 
been captured since, most of them in the eastern 
Basin, and especially in Turkish waters (Lanteri et 
al., 2017). Investigations regularly conducted in the 
latter area, focusing on elasmobranch species and 
supported by local fishermen actively helping the 
researchers, have enabled the collection of the spe-
cimen of A. superciliosus presented in this paper, 
which also provides comments about the species’ 
origin and distribution in the same area and in the 
wider Mediterranean Sea.
MATERIAL AND METHODS
On 23 September 2012, a specimen of A supercili-
osus was captured by a pelagic longline at a depth of 
1100 m off Fethiye, a city by the Aegean Sea, located 
at 36° 23’ N and 29° 00’ E (Fig. 1). The specimen was 
a female measuring 150 cm in total length (TL), and 
weighing 30.2 kg (Fig. 2). It was caught together with 
a Mediterranean moray eel Muraena helena Linnaeus, 
1758, an oilfish Ruvettus pretiosus Cocco, 1829 and a 
swordfish Xiphias gladius, Linnaeus 1758.
RESULTS AND DISCUSSION
The specimen was identified as A. superciliosus 
based on the combination of the following main 
morphological characters: species-typical elongated 
upper lobe; snout rather long, bulbous; eyes very 
large, with orbits reaching the dorsal surface of 
the head; horizontal groove present on either side 
of head above the gills; labial furrows absent; first 
dorsal fin closer to pelvic fins than to pectoral fins; 
dorsal surface dark blue, belly cream to greyish. 
These morphological characters are in total agre-
ement with Compagno (1984), Quéro (1984) and 
Ebert & Stehmann (2013), and allow to include the 
present specimen among the nine A. superciliosus 
recorded to date in Turkish waters (Tab. 1). Ebert 
Fig. 1: Records of Alopias superciliosus captured in Turkish waters by chronological order. 1: Marmaris, Aegean Sea 
(Clo et al., 2009). 2: Gökova Bay, Aegean Sea (Kabasakal, unpubl. data). 3: Sivrice, Aegean Sea (Kabasakal et al., 
2011). 4: Silivri, Sea of Marmara (Kabasakal & Karhan, 2007). 5: Fethiye, Aegean Sea (Kabasakal et al., 2011). 6: 
Silivri, Sea of Marmara (Kabasakal et al., 2011). 7: Fethiye, Aegean Sea (This study). 8-9: Antalya, NE Mediterranean 
(Soldo et al., 2014). Insert: asterisk indicates the capture site of the present specimen.
Sl. 1: Zapisi o pojavljanju velikooke morske lisice v turških vodah po kronološkem redosledu. 1: Marmaris, Egejsko 
morje (Clo in sod., 2009). 2: Gökova Bay, Egejsko morje (Kabasakal, neobjavl. podatki). 3: Sivrice, Egejsko morje 
(Kabasakal in sod., 2011). 4: Silivri, Marmarsko morje (Kabasakal & Karhan, 2007). 5: Fethiye, Egejsko morje (Ka-
basakal in sod., 2011). 6: Silivri, Marmarsko morje (Kabasakal in sod., 2011). 7: Fethiye, Egejsko morje (pričujoča 
raziskava). 8-9: Antalya, SV Sredozemsko morje (Soldo in sod., 2014). Manjša slika - zvezdica označuje mesto ulova 
obravnavanega primerka.
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Okan AKYOL et al.: CAPTURE OF A BIGEYE THRESHER SHARK ALOPIAS SUPERCILIOSUS (ALOPIIDAE) IN TURKISH WATERS (EASTERN MEDITERRANEAN SEA), 31–36
& Stehmann (2013) noted that size at birth ranged 
between 100 and 140 cm TL, with the largest adult 
A. superciliosus ever captured reaching 484 cm TL. 
Since female specimens mature between 332 and 
356 mm TL (Ebert & Stehmann, 2013), the present 
A. superciliosus could be considered at least as a 
juvenile female. 
Serena (2005) noted that A. superciliosus was 
an occasional or rather rare species in the Mediter-
ranean Sea. Conversely Clo et al. (2008) and Cor-
sini-Foka & Sioulas (2009) considered the species 
abundant in some areas. De Maddalena & Baensch 
(2005) noted that the recent findings of A. superci-
liosus indicate that the shark occurs in the Mediter-
ranean and is rather abundant in the eastern Basin, 
where a viable population appears to be progressi-
vely establishing (Kabasakal et al., 2011). However, 
no nursery grounds for A. superciliosus were clearly 
observed anywhere in the Mediterranean Sea, and 
some traits of its reproductive biology are locally 
still unknown. 
The status of the species in some Mediterranean 
areas remains questionable, due to fact that it is 
also noted as endangered (Walls & Soldo, 2016). 
Additionally, it is facing interspecific competition 
pressure from its closely sympatric species, thresh-
Fig. 2: A - specimen of Alopias superciliosus captured off Fethiye (Aegean Sea), scale bar = 75 mm. B - head of the 
same specimen, scale bar = 75 mm.
Sl. 2: A - primerek velikooke morske lisice, ujet v vodah pred Fethiye (Egejsko morje), merilo = 75 mm. B - glava 
primerka, merilo = 75 mm.
Record Date Area Depth (m) TL (cm) Fishing gear References
1 ? /04/2005 Marmaris, Aegean Sea ? ? ? Clo et al. (2009)
2 23/ 05/2005 Gökova Bay, Aegean Sea ? 350 ? Kabasakal (unpub. data)
3 21/05/2006 Sivrice, Aegean Sea 100 400 gill net Kabasakal et al. (2011)
4 23/02/2007 Silivri, Sea of Marmara ? 450 purse-seine Kabasakal & Karhan (2007)
5 28/02/2011 Fethiye, Aegean Sea 110 450 trammel net Kabasakal et al. (2011)
6 02/07/2011 Silivri, Sea of Marmara ? 250 purse-seine Kabasakal et al. (2011)
7 23/09/2012 Fethiye, Aegean Sea 1100 150 longline This study
8 15/04/2015 Antalya, NE Mediterranean 500 ? ? Soldo et al. (2014)
9 05/05/2015 Antalya, NE Mediterranean 500 ? trawl Soldo et al. (2014)
Tab. 1: Detailed records of specimens of Alopias superciliosus caught in Turkish waters.
Tab. 1: Podrobni zapisi o primerkih velikooke morske lisice, ujetih v turških vodah.
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Okan AKYOL et al.: CAPTURE OF A BIGEYE THRESHER SHARK ALOPIAS SUPERCILIOSUS (ALOPIIDAE) IN TURKISH WATERS (EASTERN MEDITERRANEAN SEA), 31–36
er shark Alopias vulpinus (Bonnaterre, 1788), 
which is locally somewhat more abundant. The 
best example of such competition is probably the 
Maghreb shore, where A. superciliosus does not oc-
cur and A. vulpinus is commonly caught (Hemida, 
2005; Hemida 2019; pers. comm., Rafrafi-Nouira 
et al., 2019).
The first Mediterranean records of A. super-
ciliosus occurred during 1952-1954 according to 
Corsini-Forkas & Sioulas (2009), with 40 other re-
cords reported since (Lanterni et al., 2017). The first 
reports on the species came from the western Basin, 
suggesting a migration of A. superciliosus from the 
eastern tropical Atlantic to the Mediterranean Sea 
through the Strait of Gibraltar. It appears that most of 
the subsequent records of A. superciliosus reported 
by Lanterni et al. (2017) occurred in the eastern 
areas, therefore a migration of the species toward 
these areas remains a valid hypothesis.
A. superciliosus is known throughout the Indian 
Ocean, where viable populations are successfully 
established (Bass et al., 1975; Das et al., 2016). Al-
though it is not recorded in the Red Sea (Golani & 
Fricke, 2005), a migration of the species into the 
Mediterranean Sea through the Suez Canal cannot 
be totally ruled out. It is evident that A. superciliosus 
does not originate from the Mediterranean Sea; rather, 
it is a vagrant species – a Herculean migrant (sensu 
Quignard & Tomasini, 2001) or a Lessepsian migrant 
(sensu Por, 1978), or having perhaps both origins. 
Similar patterns were also reported for the milk shark 
Rhizoprionodon acutus (Rüppell, 19837) by Ben 
Amor et al. (2016). Consequently, the origin of A. su-
perciliosus in the Mediterranean could and should be 
determined using molecular tools. Still, whatever the 
origin of A. superciliosus, the latter should be defined 
as an alien species among the fish species known to 
date in this sea (see Golani et al., 2017).
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Okan AKYOL et al.: CAPTURE OF A BIGEYE THRESHER SHARK ALOPIAS SUPERCILIOSUS (ALOPIIDAE) IN TURKISH WATERS (EASTERN MEDITERRANEAN SEA), 31–36
ULOV VELIKOOKE MORSKE LISICE ALOPIAS SUPERCILIOSUS (ALOPIIDAE) V TURŠKIH 
VODAH (VZHODNO SREDOZEMSKO MORJE)
Okan AKYOL & Tevfik CEYHAN
Ege University, Faculty of Fisheries, 35440, Urla, Izmir, Turkey
Christian CAPAPÉ
Laboratoire d’Ichtyologie, Université de Montpellier, case 104, 34095 Montpellier cedex 5, France
e-mail: capape@univ-montp2.fr
POVZETEK
Avtorji poročajo o novem primeru pojavljanja velikooke morske lisice, Alopias superciliosus (Lowe, 1839). Do 
danes je bilo v turških vodah potrjenih 9 zapisov o pojavljanju te vrste, na podlagi katerih bi lahko sklepali, da se je 
viabilna populacija te vrste uspela ustaliti v obravnavanem območju, čeprav bi to hipotezo zanesljivo potrdili novi 
podatki. Avtorji razpravljajo o razširjenosti vrste v Sredozemskem morju, na podlagi katerih menijo, da vrsta ne do-
muje v njem, ampak je vanj najverjetneje zašla kot selivka iz vzhodnega tropskega Atlantika ali iz Indijskega oceana. 
Ključne vrste: Chondrichthyes, Alopiidae, razširjenost, populacija, selitev
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