ANNALES · Ser. hist. nat. · 21 · 2011 · 2 
157
Short scientific article                    UDK 591.9:597.535(262.32)
Received: 2011-10-25
ON THE RECORD OF THE MORAY EEL (MURAENA HELENA LINNAEUS, 
1758) IN SLOVENIAN COASTAL WATERS (GULF OF TRIESTE, NORTHERN 
ADRIATIC)
Lovrenc LIPEJ
Marine Biology Station, National Institute of Biology, SI-6330 Piran, Fornače 41, Slovenia
E-mail: lipej@mbss.org
Sašo MOšKON
Harpha Sea d.o.o. Koper, SI-6000, Koper, Čevljarska 8, Slovenia
ABSTRACT
The authors report on the record of the moray eel (Muraena helena) in Slovenian coastal waters (Gulf of Trieste, 
northern Adriatic). The specimen was caught by a diver with a speargun in June 2011. The moray eel measured 
1,127 mm in total length and weighed 4,120 g. The estimated age of the moray eel was about 12 years. This is the 
first recorded case of the occurrence of moray eel in Slovenian waters.
Keywords: moray eel, Muraena helena, first record, Gulf of Trieste
PRIMA SEGNALAZIONE DI MURENA MEDITERRANEA (MURAENA HELENA 
LINNAEUS, 1758) IN ACQUE COSTIERE SLOVENE (GOLFO DI TRIESTE, ADRIATICO 
SETTENTRIONALE)
SINTESI
Gli autori riportano il ritrovamento della murena mediterranea (Muraena helena) nelle acque costiere slovene 
(Golfo di Trieste, Adriatico settentrionale). L’esemplare è stato catturato da un sommozzatore, con l’ausilio di un 
fucile subacqueo, nel giugno del 2011. La lunghezza totale della murena era pari a 1127 mm, per un peso di 4120 
g. L’età dell’esemplare è stata valutata essere attorno ai 12 anni. Tale cattura è il primo ritrovamento di questa specie 
in acque slovene. 
Parole chiave: murena mediterranea, Muraena helena, prima segnalazione, Golfo di Trieste
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INTRODUCTION
The Mediterranean moray eel (Muraena helena 
Linnaeus, 1758) is one of three species of muraenids, 
known to occur in the Adriatic Sea. The second mura-
enid in the area is the brown moray Gymnothorax uni-
color, which is a rare and less known fish in the whole 
Adriatic Sea (Tortonese, 1970; Jardas, 1996). The third 
muraenid species is a recently discovered non native 
species, the fangtoothed moray Enchelycore anatina, 
which was photographed in waters off two southern 
Adriatic islands (Lipej et al., 2011). The Mediterranean 
moray eel is a subtropical, reef-associated resident spe-
cies, living across the eastern Atlantic from south of the 
British Isles to Senegal, including the Mediterranean, the 
Azores, Madeira, the Canary and the Cape Verde Islands 
(Tortonese, 1970; Bauchot, 1986).
There is a lack of published data on the Mediterrane-
an moray in the Adriatic Sea, but also in the Mediterra-
nean as a whole (Matić-Skoko et al., 2011). Jardas (1996) 
reported on the presence of the moray eel in the middle 
and southern Adriatic Sea, whereas in the northern part 
it is considered rare. In older checklists, M. helena was 
not recorded for the Gulf of Trieste (for example, Tro-
is, 1875; Perugia, 1881; Stossich, 1881; Faber, 1883). 
In the “Key for identification of vertebrates in Slovenia” 
Marčeta (1999) did not mention this species among the 
vertebrates known to be recorded in Slovenia.
The aim of this paper is to present the first data on 
the occurrence of a single specimen of moray eel for the 
Slovenian coastal sea.
MATERIAL AND METHODS
A diver caught the moray eel with a speargun whi-
le shore diving on 18 June 2011 in the early morning 
hours. The speargun was equipped with the Panasonic 
DMC-FT2 camera. The diver sighted the moray eel at 
6.7 m of depth on a rocky bottom off the town of Piran 
(Fig. 1). The habitat where the moray eel was caught 
is characterized by sandstone boulders covered mainly 
with sponges and colonies of the Mediterranean stony 
coral Cladocora caespitosa. The surroundings of the 
moray eel hole were almost completely covered with 
sponges Verongia aerophoba and Chondrilla nucula. At 
the time of capture, the moray eel was emerging its head 
out of the vertical hole. The diameter of the hole was 
estimated to measure 12 cm. The diver erroneously tho-
ught that the fish was a European conger Conger conger 
Linnaeus, 1758, which is a rather common anguilliform 
species in the area. After the capture, the specimen was 
photographed and measured with a hand meter to the 
nearest millimetre and weighed to the nearest gram.
RESULTS AND DISCUSSION
The specimen of moray eel (Figs. 2, 3) was determi-
ned due to typical diagnostic characters. The body was 
elongated and typical anguilliform. The dorsal fin began 
behind its head and extended to the caudal fin. The pe-
lvic and pectoral fins were absent. The head was short 
and massive. The gill opening was reduced to a small 
lateral pore. The specimen exhibited a typical marbled 
colour pattern. The moray eel measured 1,127 mm in 
total length (TL) and weighed 4,120 g (Tab. 1). Since 
Muraena helena can range from 419 to 1,340 mm TL 
and weigh between 109 and 6,450 g (Jiménez et al., 
2007), the studied specimen could be considered as 
quite big. According to the length-at-age equation used 
Fig. 1: Map of the studied area with the locality, where 
the specimen of Muraena helena was caught.
Sl. 1: Zemljevid obravnavanega območja, kjer je bil ujet 
primerek murene (Muraena helena).
Parameter Length/weight
% of 
standard 
length
Standard length (mm) 1,127 100.00
Head length (mm) 136 12.07
Eye diameter (mm) 8 0.71
Preorbital length (mm) 23 2.04
Jaw length (mm) 55 4.88
Predorsal distance (mm) 121 10.74
Dorsal fin length (mm) 1,006 89.26
Anal fin length (mm) 542 48.09
Height at orbit (mm) 39 3.46
Height at gill opening (mm) 112 9.94
Weight (g) 4,120
Tab. 1: Biometric data for the specimen of M. helena.
Tab. 1: Biometrični podatki za primerek murene.
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by Matić-Skoko et al. (2011), the estimated age derived 
from the total length and weight of our specimen would 
be 12 years. The same authors consider the life span to 
be around 15 years.
P. Kružić (in litt.) recorded this species at the island of 
Čutin. M. Kovačić (pers. comm.), the curator of marine 
ichthyofauna and other vertebrates in the Rijeka Natural 
History Museum, has never recorded this species dur-
ing his ichthyological surveys in the Kvarner area. Up to 
date the moray eel has not been recorded off the west-
ern Istrian coast. However, A. Jaklin (Centre for Marine 
Research, Rovinj, pers. comm.) posses an information 
about a small specimen of moray eel, found at a depth 
of 30 m close to the islet of Fraškera, south of the very 
tip of the Istrian peninsula.
The occurrence of the moray eel in Slovenian waters 
could be related to the northward spreading of southern 
species. As in many other regions, also in the Adriatic 
Sea the present-day sea warming ultimately favours the 
spreading of thermophilous fish species. Many cases of 
this phenomenon in the Adriatic Sea have already been 
pointed out by various studies (Dulčić et al., 1999; Li-
pej & Dulčić, 2004). Such indicator fish species, which 
were able to reach the southern tip of the Istrian penin-
sula, are for example Thalassoma pavo (P. Kružić, pers. 
comm.) and Sphoroides pachygaster (Dulčič, 2002). 
Certain fish species which could be related to the north-
ward spreading and have recently been confirmed in the 
Slovenian part of the Adriatic Sea are Coryphaena hip-
purus (Dulčić & Lipej, 1997) and Pomatomus saltator. 
The later was caught in great numbers in spring 2011 at 
the mouth of the Dragonja River.
The moray eel in Slovenian coastal waters prob-
ably arrived from waters off the western Istrian penin-
sula. The possibility that the moray eel has simply been 
overlooked in the area is to our opinion less realistic. In 
fact, in the period from 1999 to 2011 there were regular 
faunistic surveys, especially visual census techniques, 
performed in the studied area. Additionally, we cannot 
completely disregard the possibility of an intentional re-
lease of aquarium specimens in the marine ecosystem. 
Only in the nearby future we will be able to ascertain 
whether this case of the moray eel should be considered 
as a rather exceptional one or should it be attributed to 
a spreading of moray eel range extension.
ACKNOWLEDGMENTS
Authors wish to express their gratitude to Valter Žiža, 
Iztok Škornik, Dr. Marcelo Kovačić, Dr. Petar Kružić, 
Dr. Andrej Jaklin, Roberto Odorico, Nicola Bettoso, Dr. 
Tom Turk, Borut Furlan and other colleagues who shared 
with us their information regarding the occurrence of 
the moray eel in the Adriatic Sea. Special thanks also 
goes to Dr. Sanja Matić-Skoko for her precious help, 
useful scientific literature and her knowledge on murae-
nids which she shared with us.
Fig. 3: A close photo of the head of moray eel. (Photo: 
S. Moškon).
Sl. 3: Bližinski posnetek glave murene. (Foto: S. Moškon).
Fig. 2: 1,127 mm long specimen of M. helena, caught 
in waters off Piran (Gulf of Piran). (Photo: S. Moškon)
Sl. 2: 1127 mm dolg primerek murene, ujete v vodah 
blizu Pirana (Piranski zaliv). (Foto: S. Moškon)
ANNALES · Ser. hist. nat. · 21 · 2011 · 2 
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O POJAVLJANJU MURENE (MURAENA HELENA LINNAEUS, 1758) V SLOVENSKIH 
OBALNIH VODAH (TRŽAŠKI ZALIV, SEVERNI JADRAN)
Lovrenc LIPEJ
Morska biološka postaja, Nacionalni inštitut za biologijo, SI-6330 Piran, Fornače 41
E-mail: lipej@mbss.org
Sašo MOšKON
Harpha Sea d.o.o. Koper, SI-6000, Koper, Čevljarska 8
POVZETEK
Avtorja poročata o pojavljanju murene (Muraena helena) v slovenskih obalnih vodah (Tržaški zaliv, severni Ja-
dran). Primerek je ujel potapljač s podvodno puško junija 2011. Murena je v celotno dolžino merila 1127 mm in teh-
tala 412 g. Ocenjena starost primerka je 12 let. To je prvi zabeležen primer pojavljanja murene v slovenskih vodah.
Ključne besede: murena, Muraena helena, prva najdba, Tržaški zaliv
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