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Tongue louse, toad fish, rabbit fish… in the Mediterranean, species from elsewhere are less and less rare

Among non-indigenous marine (and invasive) species, the blue crab is undoubtedly the star of the past two years. But he is not the only intruder in the waters and lagoons of the Gulf of Lion. The carnivorous ctenophore Mnemiopsis Leidyi or the crepidula are monitored. Other “critters” are also appearing and multiplying. This is the case with toad and rabbit fish or the terrifying tongue-eating louse. We introduce you…

Not a day goes by without mentioning the invasive and destructive presence of the blue crab in the lagoon areas. Callinectes Sapidus has been at the top of the bill for months and is the subject of research and studies aimed at eradicating it if possible or at promoting it commercially, its taste qualities being, in fact, undeniable.

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We would almost forget the presence of other non-indigenous marine species which also cause damage and could wreak havoc in the event of a reduction. The CPIE (Permanent Center for Environmental Initiatives) of the Thau Basin has been leading the network of Sentinels of the Sea in Occitania for several years, aiming to collect observations from citizens. He is currently setting up the Alien Occitanie system, “a network for improving knowledge of non-indigenous marine species based on citizen monitoring”.

For example, in partner ports, volunteer boaters are invited to take samples from the hulls of boats. An awareness campaign for boaters, in parallel with the training of Ecogestes ambassadors, is underway. Finally, information and awareness tools are widely distributed. In addition, online resources, such as a guide to species, or sites and applications listing observations (or sharing them) are available.

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ALIEN Occitanie, a network to spot marine species from elsewhere

The terrifying tongue louse

Each in turn, the Enim (non-indigenous marine species) are, at the rate of their appearance, the seasons, their proliferation, propelled to the fore. In recent weeks, with the return in large numbers of fishermen to the beach, it is the tongue-eating louse Cerathotoa italica which is causing the buzz. According to blogger Jérémie Cloix, administrator of the Surfcasting Méditerranée group on Facebook (more than 4,500 members), the presence of this parasite is increasingly observed. Including himself.

The tongue-eating louse squats in the mouth of one in two fish in overfished areas.
DR – Jérémie Cloix / Mediterranean Surfcasting

The existence of this parasite is worthy of a horror movie. It vaguely resembles a maggot and has claws. It enters the fish via its gills and then clings to its tongue. Hematophagous, it feeds on blood. It is by language that it feeds on that of its favorite species, seabream, marbled seabream, seabream and sometimes pageot. After it devours the tongue, it ends up replacing it! According to what Jérémie Cloix was able to observe, “when several of them have taken up residence in the mouth of the fish, one finds a large one in place of the tongue and several small ones at the back of the throat or attached to the gills”.

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No risk to human health

According to the scientific data site Doris (Observational Data for the Recognition and Identification of Underwater Fauna and Flora), “This intraoral endoparasite poses no risk to humans when consuming the host fish. It slows the growth of host fish and limits their reproductive, developmental and life expectancy. Researchers have found that ‘Betty’ thrives in areas overexploited by fishing In a protected area, close to Spain, only 30% of the fish are infected, whereas in intensive fishing areas, in Italy for example, the rate of victims (prevalence of the parasite) reaches so 47%. Similarly, the impact on fish health is more negative in overfished areas than in protected areas. There are about thirty species of Ceratothoa known in the world, including 8 in the Mediterranean”. Phew. According to Jérémie Cloix, fish have a surplus of mucus in the mouth. It only takes one rinse to eliminate it.

The presence of this formidable does not affect the edibility of the fish.

The presence of this formidable does not affect the edibility of the fish.
DR – Jérémie Cloix / Mediterranean Surfcasting

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Toadfish, rabbitfish, same fight

The other two Enim that have been in the news in recent months are the toad fish and the rabbit fish which, in addition to being big eaters, are sometimes cannibalistic, are venomous, poisonous, or even both (hence the usefulness to learn to recognize them). Regarding the first, the fishing cooperative in the Gulf of Lion, Sathoan, alerted professionals in a publication last fall. “The silver-cheeked toadfish (Lagocephalus sceleratus), is a species that comes from the Red Sea and was introduced into the Mediterranean through the Suez Canal. This fish is considered one of the most harmful species in the Mediterranean Sea, due to its potent neurotoxin, its impacts on marine biodiversity, and the increased cost and labor it inflicts on fishermen The capture and consumption of this puffer fish is prohibited in almost all countries bordering the Mediterranean. This fish is now extended to the whole of the Mediterranean and the Black Sea”.

The rabbitfish, also from the Red Sea, is placed under surveillance. He is herbivorous, like the saupe (reputed to be hallucinogenic if it is not emptied as soon as it is caught) that we know well on our coast. However, the rabbit would be a real scourge if it were to colonize our coasts because it is capable of devouring forests of algae, with the consequences that we imagine on biodiversity.

In summary, maritime traffic, warming waters, new currents, etc. have not finished occupying scientists and worrying fishing professionals and environmental protectors.

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