“Watch Out for These Four!”: Eyes on the Sea to Spot Invasive Alien Species
The ISPRA/CNR-IRBIM Campaign Restarts
The mapping of lionfish (Pterois miles) sightings in the Mediterranean, updated in March 2025, reports 1,840 records from various countries around the basin. The species is also spreading in Italian waters, with the Ionian Sea confirmed as one of the most vulnerable areas.
Today, fishermen, divers, and anyone who has seen or caught a lionfish or one of three other potentially dangerous tropical species — the silver-cheeked toadfish, the dusky spinefoot, and the marbled spinefoot — are once again invited to support the “Watch Out for These Four!” alert campaign, aimed at informing the public about the presence of these invasive species in our seas.
The Italian Institute for Environmental Protection and Research (ISPRA) and the Institute for Biological Resources and Marine Biotechnologies of the National Research Council in Ancona (CNR-IRBIM), in collaboration with the AlienFish project, are relaunching the “Watch Out for These Four!” campaign. The initiative includes practical guidelines for identifying the species, preventing accidents, and contributing to monitoring their spread, encouraging citizens to document sightings with photos or videos and submit them via the provided link.
Alternatively, reports can be sent via WhatsApp to +39 320 4365210 or through the Facebook groups Oddfish and Fauna Marina Mediterranea, in collaboration with the AlienFish project, using the hashtag #Attenti4.
Just a few weeks ago, the scientific journal Mediterranean Marine Science published a study — conducted by CNR-IRBIM and ISPRA — offering an updated and in-depth overview of the lionfish’s distribution in the Mediterranean Sea.
This campaign continues the efforts launched in 2022, responding to the increasing number of reports and captures of alien species in Italian waters, particularly lionfish, by divers and fishermen. The data collected has been visualized through new distribution maps and compared with predictive models developed in previous studies. All new observations have been integrated into the ORMEF portal dataset, now representing the most up-to-date database on Pterois miles presence in the Mediterranean.
Manuela Falautano, ISPRA researcher and national coordinator for the “Watch Out for These Four!” campaign, states: “The rise in reports and catches by fishermen and divers confirms their crucial role in supporting researchers in monitoring alien species, but also highlights the need to expand the involvement of sea professionals and promote clear communication to the public about potentially dangerous species — without causing alarm.”
Ernesto Azzurro, CNR-IRBIM researcher and lead author of the lionfish study, adds:“Most new sightings are concentrated in the Ionian Sea — one of the areas projected to be at highest risk of tropical species invasions due to climate conditions, along with the southern Adriatic. Our findings strongly support the reliability of our predictive models and underline the urgent need for effective monitoring and management strategies.”
🐟 Meet the Four Aliens:
Lionfish (Pterois miles) – Entered through the Suez Canal and first reported in Italy in 2016. It is one of the world’s most invasive species and has colonized much of the western Atlantic coast, causing major ecological damage. It is edible, but its spines can cause extremely painful stings, even up to 48 hours after the fish’s death.
Silver-cheeked toadfish (Lagocephalus sceleratus) – Also entered through the Suez Canal, first reported in Italy in 2013. Recognizable by dark spots on its grey-silver back, this species contains a highly toxic neurotoxin, dangerous even after cooking. It also has powerful teeth capable of inflicting serious bites.
Dusky spinefoot (Siganus luridus) and Marbled spinefoot (Siganus rivulatus) – Both herbivorous invasive species, first reported in Italy in 2003 and 2015, respectively. They are edible, but care must be taken with their spines, which can still cause painful stings even after death.