First record of the Lessepsian migrant species Lagocephalus sceleratus ( Gmelin , 1789 ) ( Actinopterygii : Tetraodontidae ) in the Central Mediterranean

The Lessepsian migrant fish Lagocephalus sceleratus is being recorded for the first time from the gulf of Gabès (Central Mediterranean, Tunisia). The record is based on a single specimen collected in December 2010. Previous records of the species were confined to the Levantine and Aegean Seas. Recent research reveals that this species is extending its distribution area to the western Mediterranean. The species is toxic, containing tetrodotoxin (TTX) that paralyses the nervous and respiratory systems. Actions of awareness were taken in Tunisia to alert consumers and fishermen on the potential danger of this species.


Introduction
The silverstripe blaasop Lagocephalus sceleratus (Gmelin, 1789) is an Indo-Pacific migrant, but has been recorded in the Mediterranean Sea since 2003.It has also been recorded in Turkey (the Aegean Sea) (Filiz and Er 2004;Akyol et al. 2005;Bilecenoglu et al. 2006), in Greece (the Aegean Sea) (Corsini et al. 2006;Minos et al. 2010), in the Cretan Sea (Greece) (Kasapidis et al. 2007), in the Levantine (Golani and Levy 2005;Bilecenoglu et al. 2006) and in the Lebanon (Carpentieri et al. 2009).This report records the first occurrence of L. sceleratus, in the southern gulf of Gabes, Central Mediterranean.

Methods
A single specimen of Lagocephalus sceleratus was caught by a bottom trawler on 8 December 2010, at the southern end of the Gulf of Gabès (33°50′N; 11°52′E).It is currently located in a collection at the Sfax Centre of the National Institute of Sea Sciences and Technologies, catalogue no.TETRA003.

Results and discussion
The obtained specimen of Lagocephalus sceleratus had a total length of 60 cm, and weighed 2687 g (Figure 1).The body is elongated and cylindrical, slightly compressed laterally and ventrally with a tapering caudal peduncle.Small spinules are present on the dorsal area, extending from behind the upper lip to the dorsal fin, but the spinules do not reach the cloacae ventrally.No scales are present on the rest of the body surface.There is no pelvic fin.The dorsal and anal fins are opposite each other with a posterior position and the caudal fin is lunate.The colour of the dorsal area is brownish-grey with regularly distributed black dots.The abdominal side is white and rough.Wide silver bands are present laterally, from the mouth to the caudal fin.The pectoral fin base has a black color.A silver blotch was present in front and below the eye.
All measurements and meristic features are reported in Table 1.
The family Tetraodontidae is represented by nine species in the Mediterranean Sea (Golani et al. 2002;Akyol et al. 2005;Corsini et al. 2005;Golani et al. 2006).Five species have been    L. sceleratus is a potential risk to humans, since it contains tetrodotoxin (TTX) that may be a source for food poisoning (Kasapidis et al. 2007;Bentur et al. 2008;Eisenman et al. 2008;Katikou et al. 2009).It is considered as a delicious sea food in Suez City, Egypt, where it is illegally sold in spite of several fatal poisonings being reported there (Zaki 2004).Pufferfish is considered a delicacy in Japan, where it is known as fugu; the poisonous organs are removed by specialist cooks, the day the fish is caught.
L. sceleratus should not be consumed in Tunisia, since the skin and internal organs contain a neurotoxin that can paralyse both the nervous and respiratory systems.The toxin is not affected by heat or cooking (Arakawa et al. 2010).
Awareness of this highly toxic fish is urgently required for both fishermen and consumers.It is important to (i) notify local authorities about the presence of newly captured fish and (ii) avoid its consumption.Distribution of a brochure with photographic images and information pertaining to the fish are in press.
Lagocephalus sceleratus has shown a rapid expansion throughout the eastern Mediterranean Sea since its first appearance, reaching to the northern most parts of the Aegean Sea.This new occurrence south of the gulf of Gabes (Central Mediterranean) obviously suggests a successful adaptation of the species and a westerly movement into the Mediterranean Sea (Figure 2; Appendix 1).
Perhaps the gradual warming of the sea in the context of global warming (Brauch 2010), also facilitates the immigration of this Indo-pacific alien species.This concept leads to a more complex vision of the overall colonization process in the entire Mediterranean, especially since we are aware that L. sceleratus is in the list of the 100 "Worst Invasives" in the Mediterranean (Streftaris and Zenetos 2006)

Figure 2 .
Figure 2. Map showing the locations where the silverstripe blaasop Lagocephalus sceleratus has been captured (see Appendix 1 for details).

Table 1 .
Measurements and counts for the Lagocephalus sceleratus specimen caught in the gulf of Gabes (Central Mediterranean), December 2010.
Coordinates are approximately determined from data in the text: not reported as such by the authors. *