Another alien in the Mediterranean: porcupine fish found on the coast of Lazio

It may have arrived from the eastern Atlantic, crossing the Strait of Gibraltar. Or, alternatively, having been carelessly released into the sea from an aquarium. A speckled porcupine fish (Chilomycterus reticulatus the scientific name) was found beached in Santa Marinella, along the Lazio coast: it is the second report ever in the Mediterranean (in 2008, in Sant’Antioco, the previous observation) for a species of subtropical porcupine fish, whose marketing for food purposes has already been prohibited since 1992: it can in fact accumulate tetrodotoxin, although to a lesser extent than the puffer fishes of the family Tetraodontidae.

It was a fisherman who reported the specimen, 60 centimeters long, in Santa Marinella: thanks also to the campaign “Beware of those 4!” launched in recent months by Ispra and Cnr IRBIM to inform citizens of the presence of four alien fish potentially dangerous for human health. And a team from Ispra recovered the specimen, carrying out the morphological and molecular analyzes for the identification of the species: some characteristics (starting from the inflatable body covered with large spines, teeth fused into plates and the spotted livery on the back and fins) in fact assimilated it to the Diodon holocanthus.

“Populations of speckled porcupine are reported to increase in the seas of southwest Africaand in particular in the Azores, a circumstance which – together with the particularly significant size of the beached fish – make the hypothesis plausible that accidentally entered the Mediterranean through the Strait of Gibraltar“, points out Manuela FalautanoIspra researcher directly involved in awareness campaigns for the recognition of alien species potentially harmful to humans.

“Although the observation has an episodic character, it is certainly about a new confirmation of the changes taking place in the Mediterranean, a sea which, despite its small size, proves to be the most susceptible to invasions by alien species, in terms of number and speed of diffusion. In the case of the porcupine fish – continues Faulatano – the rarity of the observations may perhaps make the news: the species has a circum-global distribution, populates sub-tropical and temperate areas and certainly the brake is constituted by the temperature of our sea, still too cold”. A sea that, however, is gradually warming up. So things could soon change.

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Also because if the Chilomycterus reticulatus is an almost completely new guest, On the other hand, the presence of puffer fish and porcupine fish is increasing in the Mediterranean. “That’s right. – he confirms Fabio Crocettaresearcher of the Anton Dohrn Zoological Stationexpert on alien and invasive species – Just think of the smooth puffer fish, Sphoeroides pachygaster, which has invaded the western Mediterranean since the 1980s, expanding in a few decades to the eastern Mediterranean and the Adriatic, one of the coldest sub-basins in the area. Or the spotted porcupine fish, Diodon hystrixvery similar to the species found on the Lazio coast, and already known in the Mediterranean for three sightings”.

“Among the most invasive species, the spotted puffer fish must certainly be mentioned Lagocephalus sceleratus, with important impacts on ecosystems and above all on juveniles of other fish. In general – continues Crocetta – although the Levantine basin is home to several alien species, including numerous puffer fish and porcupines from the Red Sea and the Indo-Pacific, the Italian coasts are also subject to the arrival of these and other species. In most cases these are important predators, which can upset food webs at different levels. While, unfortunately, we can do nothing against species that come ‘naturally’ from neighboring ranges, greater human attention would be desirable in the case of species arriving by sea transport or deliberate release”.

The reporting of porcupine fish, which took place through the so-called “citizen science”, has also led Ispra and Cnr-Irbim to renew their invitation not to release exotic species living in natural environments, to limit their chances of escaping from confined environments and to report also to learn about the new exotic species that populate our seas starting from the potentially dangerous ones. “The very fact that a fisherman did it, suspicious of some physical characteristics in common with the spotted puffer fish, confirms the growth of a widespread sensitivity on the part of citizens and operators of the sea, who are our first sentinels of the sea”, adds Falautano.

“Monitoring the presence of alien or invasive species is fundamental – he continues – because their alterations can translate into a competition for space and for food resources, in direct predation, in hybridization with native species and in the transmission of diseases . Among the most striking cases are rabbitfish Siganus luridus And Siganus rivulatus which, due to their herbivorous activity, have a negative impact on the algae of the superficial rocky coastal area, the algae Caulerpa racemosa And Caulerpa taxifoliawhich threaten the posidonia meadows in regression, and the spotted puffer fish, Lagocephalus sceleratusa highly toxic species that can also cause considerable damage to fishing activity”.