SOME NEW DATA ON THE OCCURRENCES OF SCHEDOPHILUS OVALIS (CUVIER, 1833)
(PISCES: CENTROLOPHIIDAE) IN THE EASTERN ADRIATIC
J. Dulcic
1*
, V. Onofri
2
, I. Jardas
1
, A. Pallaoro
1
, A. Soldo
1
, B. Glamuzina
3
1
Institute of Oceanography and Fisheries, Split, Croatia - * dulcic@izor.hr
2
Institute of Oceanography and Fisheries, Dubrovnik, Croatia
3
University in Dubrovnik, Department for Aquaculture, Dubrovnik, Croatia
Abstract
Two specimens of the imperial blackfish Schedophilus ovalis (in 1979-TL=25.2 cm; in 2003- TL=37.7 cm) were caught in the southern
Adriatic. Periodically occurrences of this species could be explained by the “Adriatic ingressions”, NAOi and warming of Adriatic waters.
Key-words: Schedophilus ovalis, occurrences, Eastern Adriatic
Rapp. Comm. int. Mer Médit., 37,2004
348
Introduction
The imperial blackfish Schedophilus ovalis (Cuvier, 1833) is
present in the Eastern and Western Central Atlantic, Australia, and
throughout most of the Mediterranean (1). S. ovalis lives both in
surface waters (juvenile phase associated with ?oating wreckage and
jellyfish) and on slope bottoms in habitats which have not yet been
defined. Many aspects of its biology remain obscure (1), especially in
the Mediterranean, where it has for a long time been supposed that
that this species is rare (2). Jardas (3) noted that S. ovalis (Cuvier,
1833) is very rare species in the Adriatic Sea.
In this paper we present some new data on the occurrences of the
imperial blackfish in the eastern Adriatic.
Material and methods
The specimens were identified according to Jardas (3). They are
deposited in the Ichthyological Collection of the Institute of
Oceanography and Fisheries in Split, Croatia. The specimens were
measured to the nearest 0.1 cm (TL-total length), and weighed to the
nearest 0.1 g.
Results and discussion
On 26 June 1979 one specimen of the imperial blackfish was caught
with the deep bottom trawl in the open waters of the southern Adriatic,
about 20 Nm SE from Dubrovnik at depth of about 1000 m depth. The
total length of caught specimen was TL = 25.2 cm (no data on weight
and sex undetermined). Another specimen of the imperial blackfish
was caught on 28 July 2003 with «brankarela» (ripping hook mounted
together on the iron or wooden stick) in the open waters of southern
Adriatic, 35 Nm SE from Dubrovnik (southern Adriatic), at about
1200 m depth. The sea surface temperature was SST=26.5
0
C. The
total length was TL=37.7 cm, and weight W=820.2 g (sex unde-
termined). The growth of the imperial blakfish specimens to about 45
cm TL (4) corresponds to the first year of life. If we take this into
consideration both caught specimens in the eastern Adriatic were
juveniles (0+).
S. ovaliswas firstly recorded in the Adriatic as Centrophilus
corcyrensis(5) since it was caught in the vicinity of the KorculaIsland
(southern Adriatic). The second specimen (without measures) of this
species was captured together with S. medusophagus in Pelješac
channel (southern Adriatic) in 1982 (at depth 2 m, T=25
0
C) and it was
accompanied the occurrence of Pelagia noctiluca (6). We assume that
those periodically occurrences could be explained by the Adriatic
ingressions, NAOi (North Atlantic Oscillation Index) and warming of
Adriatic waters (7). Observations on the Adriatic ichthyofauna (period
1973-1998) showed changes in the quantitaive and qualitative
composition of the fish fauna. The number of thermophilic species has
increased; several species, scarce or rare until now are more abundant,
while others are new records (7). Dulcicet al.(7) considered that the
presence of the imperial blackfish and cornich blackfish S.
medusophagusin the Adriatic waters depends on water warming. The
northward extension of S. ovalis to the Bay of Biscay (8) and recent
occurrences of young S. ovalis along French Mediterranean coasts (9)
could support this hypothesis. Francour and Javel (9) assume that the
observations of small to medium sized S. ovalis they gathered in
2000-2001 in the Alpes-maritimes department (Cannes, Antibes,
Beaulieu/Mer) could be also explained by the present warming of
waters (10).
According to Morovic(11), the rarity of certain fish species could
be evaluated from the records in scientific literature. Same author
pointed that if the species is recorded fewer than five times, it should
be treated as a very rare species. According to this, we could still
treated the imperial blackfish (4 records in scientific literature until
now) as a very rare species in the eastern Adriatic. We must also be
careful with tools (gears) for providing target species if we want to
evaluate their rarity since it is hard to sample the imperial blackfish
(during different life phases) using conventional methods. FADs
(Fishing Attractive Devices) provide a useful tool for studying
mentioned species (12), so it could be proposed for next studies on
fish assemblages in the southern Adriatic. The results of Deudero et
al.(12) confirm the rare observations on the imperial blackfish (13) in
the Ligurian Sea. Moreover, in the Balearic Sea only 3 catches of this
species have been reported (14).
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