RANGE EXPANSION OF AN INVASIVE PUFFERFISH, LAGOCEPHALUS SCELERATUS (ACTINOPTERYGII: TETRAODONTIFORMES: TETRAODONTIDAE), TO THE SOUTH-WESTERN MEDITERRANEAN

Three specimens of silver-cheeked toadfish, Lagocephalus sceleratus (Gmelin, 1789), were caught on eastern coasts of Algeria during the winter of 2013–2014. This is the first record of this invasive species from Algeria, providing further evidence of its occurrence along north-African coasts and confirming its entry into the Western basin of the Mediterranean. The human-health implications of this toxic fish in this region are discussed.

Delta. It has since then showed a rapid expansion throughout the eastern Mediterranean Sea reaching its northernmost parts: Ionian Sea (Kapiris et al. 2014) and mid-eastern Adriatic , Libya (Milazzo et al. 2012), as well as south-western- (Jribi and Bradai 2012) and northern Tunisia (Ben Souissi et al. 2014). Table 1 summarizes the chronology of documented records (location of capture, date, number and length of the specimens, depth) of this species in the Mediterranean.
The silver-cheeked toadfish, Lagocephalus sceleratus, is one of the largest members of its family, reaching 110 cm of total length and 7 kg of weight (Nader et al. 2012). Generally, it inhabits sandy or muddy substrate areas near shallow coral reefs at depths between 18 and 100 m (Smith andHeemstra 1986, Froese andPauly 2014). In eastern Mediterranean (Rhodes), according to Kalogirou (2013), this species was found to feed on invertebrates and fish. During the early life stages, it feeds on various invertebrates. The predominant mollusc species found in the diet of the larger (> 20 cm) L. sceleratus individuals were the economically important Sepia officinalis and Octopus vulgaris. The size at which 50% of individuals are mature was estimated at 36 cm (Kalogirou 2013).
In this paper, we present the first record of the silvercheeked toadfish, Lagocephalus sceleratus, in Algerian waters, confirming the spreading of this invasive species in the western Mediterranean, and discussing the risks it poses to the health of consumers who are in general unaware of its toxicity.
During the winter of 2013-2014, three specimens of Lagocephalus sceleratus were caught on the eastern coast of Algeria (Fig. 1) Smith and Heemstra (1986) and Turan (2007).
Data on the three catches are given in Table 2. The body of the captured specimens was elongated and cylindrical, slightly compressed laterally and ventrally (Fig. 2). Back and upper flanks silvery to grey covered with black dots. The belly was white and rough. The dorsal and anal fins were short-based and posterior in position. These specimens are also characterized by: the absence of body scales, two quite distinct lateral lines, gill opening of a single slit in front of the pectoral fins, pectoral fins with a wide base and a round posterior edge, top of the pectoral fin base below the lower margin of the eye, a distinct wide silver band on the lower part of the flanks and a silver blotch in front of the eyes, dark pectoral fin base and white belly, grey-brownish dorsal area with black, regularly distributed spots of equal size.
Lagocephalus sceleratus was thought to be absent from the entire African Mediterranean coast (Shakman and Kinzelbach 2007), although its presence was suspect-ed by Golani (2010). Our observations provided additional evidence-after Jribi and Bradai (2012), Milazzo et al. (2012), and Ben Souissi et al. (2014)-of the occurrence of L. sceleratus along the North African coast and its spread in the Western Mediterranean. The relatively large size of individuals captured and their presence in the Far East of Algerian coast suggests their arrival from their last place of record on the north-western coast of Tunisia, near Tabarka (Ben Souissi et al. 2014). Among specimens collected in Tunisia, some females were mature with ripe gonads (gonad weight up to 245 g), suggesting that a breeding population may be established.
Lagocephalus sceleratus is the sixth non indigenous teleost fish species recorded in Algeria, after the Senegalese sole, Solea senegalensis Kaup, 1858 (see Chaoui and Kara 2004); the Bermuda sea chub, Kyphosus sectator (Linnaeus, 1758) (see Hemida et al. 2004); the blue-spotted cornetfish, Fistularia commersonii Rüppell, 1838 (see Kara and Oudjane 2009); the spotted halfbeak, Hemiramphus far (Forsskål, 1775) (see Kara et al. 2012); and the blackmouth splitfin, Synagrops japonicus (Döderlein, 1883) (see Hannachi et al. in press*). It is the second representative of Tetraodontidae found after the     Hemida et al. 2009). The observed increase of the mean annual temperature observed within the last several years in the Mediterranean waters (Béthoux et al. 1990, Francour et al. 1994, Vargas-Yáñez et al. 2005) could possibly explain the recent spreading of Lessepsian migrants from the eastern to the western Mediterranean basin, and their progressive geographical dispersal (Koukouras et al. 2010). In addition to the presently observed warming of the western basin, the changes in the main current circulation in the Mediterranean during the last few decades may also explain the recent spread of Red Sea species towards the western basin (see Francour et al. 2010, Otero et al. 2013. To reach the Algerian coast, L. sceleratus moved from East to West against the general current circulation along the North African coast. However, its spreading to the north-western basin, especially along the Italian and French coasts will be favoured by the Ligurian Current and we can then predict its subsequent spreading northward. Lagocephalus sceleratus has already established a population, which is colonizing new territories of the eastern Mediterranean at a relatively rapid rate. Today, it is regarded to be among the most successful invasive species in the Mediterranean Sea with a significant impact on the surrounding ecosystem and on the fisheries sector (Zenetos et al. 2005, Peristeraki et al. 2006, Streftaris and Zenetos 2006. Kalogirou (2013) classified this species as a pest for fisheries and a potential threat for biodiversity, and L. sceleratus has been included in the black list of the 18 worst fish species by the IUCN (Otero et al. 2013). More importantly, L. sceleratus is considered to be a serious hazard to consumers since it contains a strong marine toxin called tetrodotoxin (TTX), which can be lethal to humans (Kasapidis et al. 2007, Bentur et al. 2008, Eisenman et al. 2008, Katikou et al. 2009). TXT is a nonprotein organic compound (aminoperhydroquinazoline) and one of the strongest marine paralytic toxins known today (El-Ganainy et al. 2006). Up to now, three cases of poisoning of persons who had consumed this fish were reported from Israel, Lebanon (Golani et al. 2006), and Tunisia (Ben Souissi et al. 2014). In Egypt, although landing of these fishes is forbidden as a commercial species, they are illegally landed and consumed as food in the Red Sea and Gulf of Suez areas. It is considered delicious seafood in Suez City, Egypt, where it is illegally sold, decapitated and eviscerated (Halim and Rizkalla 2011) in spite of several fatal poisonings being reported there (Zaki 2004). Thus, the dramatic spread of the species along the Mediterranean coast reinforces the need for a public information campaign, especially in North African countries, to raise awareness of the dangers to human health (Azzurro 2010). To implement such an information campaign, a previous clear information workflow from scientists to public authorities and policy makers should be established.  Table 2; 48 cm TL) captured in Annaba on 11 January 2014