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Biologica/ date on Fistularia commersonii CASTRIOTA ET AL.
after seven years from its first documented record in Israel1 +N Mi.l.a. zzo
(Golani, 2000) . Azzurro et al. (2013) estimateci an invasion
speed of this species in the Mediterranean varying from hun- Marettimo .&.~
dreds of km year-1 up to 1000 km year-1 and indicating low
chlorophyll-a concentrations and high salinity as abiotic fac- Island ScJ-ac..c.a
tors of primary importance in shaping the distribution of this
species in its invaded range. ~ Pelagie O 40km
Islands 1-l
F. commersonii is an Indo-Pacific (including Red Sea)
reef-associated fish, also found in sandy bottoms (Fritzsche, Figure l. - Map of the study area with indication of sampling sites
1976) and in proximity of seagrass meadows (Bilecenoglu ( A) .
et al., 2002; Pais et al., 2007) . Its maximum reported size
is 160 cm totallength although it is most commonly found Diet
up to 100 cm (Fritzsche and Schneider, 1995; Bariche and A total of 77 specimens were eviscerateci and their stom-
Kajajian, 2012). It lives solitary or in small groups in shal-
low waters up to 128m of depth (Lieske and Myers, 1995) . achs preserved in 70% ethanol for later analysis. In the labo-
It feeds mainly on fishes, with minor support of invertebrates ratory, stomachs were dissected and their content analysed
(Kalogirou et al., 2007; Bariche et al., 2009), adopting a high under a stereomicroscope. After sorting, prey items were
variability of hunting techniques such as stalking and chas- identified to the lowest possible taxon, counted and weighed
ing, either solitarily or in foraging association with con- or to the nearest O.l mg, after removing excess water with blot-
heterospecifics (Takeuchi, 2009) . It shows camoufiage activ- ting paper. The count of fragmented prey was based on the
ity, expressing a disruptive band pattern when stationary, number of anatomica! parts traceable to single specimens
but rapidly changing to a uniform silvery coloration when in (number of eyes , mouth parts, spinal columns, tails, etc.).
motion (Thomson et al., 2000). It is a multispawner species The number of empty stomachs was recorded and used to
and, in the Levant Basin, it showed a prolonged reproductive calculate the vacuity coefficient %Cv (number of empty
season from May to October (Bariche et al., 2013). stomach/total number of analysed stomachs x 100). The
contribution of each prey to the diet of F. commersonii was
Most information on Mediterranean bluespotted cor- evaluated by calculating the following dietary indexes:
netfish populations comes from the eastern Mediterranean
where this species successfully settled and established, • percentage frequency of occurrence %F [number of
while in the centrai and western Mediterranean few studies
have been carried out, mainly focusing on genetic and para- stomachs containing prey item iltotal number of non-empty
sitological aspects (Golani et al., 2007; Merella et al., 2007, stomachs) x 100];
20 10; Sanna et al., 2011). In Sicilian waters, since 2005
several specimens of F. commersonii have been captured by • percentage abundance %N [(number of individuals of
professional fishermen, giving the opportunity to study some prey item iltotal number of all prey items) x 100];
aspects of its biology. In this work, we report preliminary
notes on diet, age and growth of bluespotted cornetfish from • percentage weight %W [(weight of prey item i/total
the centrai Mediterranean. weight of all prey items) x 100];
MATERIALS AND METHODS • index of relative importance (!Rl), using mass instead
Specimens of F. commersonii were collected from Janu- of volume: IRI = (%N+ %W)%F (Hyslop, 1980; Hacunda,
ary 2005 to December 2010, as by-catch of several fishing
activities (i.e_ trammel net, set gillnet, bottom trawl , bot- 198 1);
tom seine) in Pelagie Islands, Marettimo Island, Sciacca and
Milazzo (Sicily, centrai Mediterranean) (Fig. 1). Each speci- • percentage index of relative importance %IRI [(IRI l
men was measured to the nearest millimetre (totallength I IRI) x 100].
without filament = TL) and weighed to the nearest O.l g.
Prey size was measured to the nearest l mm and correlat-
1 The first siszhtinsz of Fistularia commersonii dates back to 1999 eci with predator size by regression analysis and tested with
in Cyprus (Kats;nevakis et al., 2009) but no specimen was pre- Student's t-test (Snedecor and Cochran, 1967).
served.
Age
Vertebrae were used for the age estimation of F. commer-
sonii, since otoliths were breakable and difficult to read. Esti-
mates of size-at-age were carried out on 46 specimens whose
vertebrae were preserved. Thoracic vertebrae were preferred
16 Cybium2014, 38(1 )
