Dozens of poisonings have been documented in Mediterranean countries, including Israel. A new international study reveals the extent of the danger and how to protect yourself from the invasive species.
The Mediterranean Sea, a source of life, recreation, and livelihood, also contains hidden dangers that we may not always be aware of. Alongside the beauty and pleasure, there is a health hazard lurking in the depths of the sea: poisonous fish. In recent years, several cases of poisoning by poisonous fish from the pufferfish family, or by their popular name known to us – Abu-Nafha, have been documented in Israel. For example, in 2022, the life of a resident of Tirat Carmel was saved after being sedated and ventilated after eating the fish he found on the beach in Haifa. In 2020, there were also reports of dogs being poisoned after eating the fish on the beaches of Hadera, Caesarea, and Beit Yanai. Abu-Nafha fish are invasive species that migrated to the Mediterranean Sea through the Suez Canal, through which a massive invasion of migratory species into the Mediterranean Sea occurred. A recently published study The study addresses the toxicity of these species and the health risks to humans. The study was conducted in a rare collaboration between marine scientists from the region: Syria, Lebanon, Turkey, Cyprus, Egypt, Libya, Tunisia, Israel, and the Gaza Strip.
Deadly poison from cyanide
In addition to pufferfish swelling up to protect themselves from predators, they also contain a neurotoxin called Tetrodotoxin. This is a powerful substance found in the bodies of most pufferfish species, and 28 percent of species contain an amount that is toxic to humans. "The main mechanism for the accumulation of tetrodotoxin in pufferfish tissues and organs is through the food chain, as part of their diet, and it is possible that it is produced by symbiotic bacteria living inside the pufferfish's body," explains Prof. Bella Galil, curator at the Steinhardt Museum of Nature, Tel Aviv University, and one of the authors of the article who has been studying invasive species from the Red Sea to the Mediterranean since 1977.
Eating tetrodotoxin is toxic to humans. 1,200 times more than cyanide, and is one of the most potent toxins in the marine environment. According to Galil, the poisoning process consists of four stages: (1) Initial symptoms appear approximately 5–30 minutes after ingestion. Symptoms are related to the nervous system and the digestive system and can include nausea, vomiting, dizziness, and abdominal pain; (2) Numbness and paralysis of the limbs appear, including changes in pupil size and reflexes; (3) Disorders occur in the nervous system, cardiovascular system, and respiratory system; (4) Severe cognitive and neurological damage occurs that may lead to loss of consciousness. Severe poisoning may be fatal within 6 to 24 hours.
Regional danger
The study focuses on the health effects of two toxic fish: The elongated legionnaire And the sea anemone, but it is mainly the legionnaire that is causing concern. "The elongated legionnaire is the most poisonous and dangerous species in the Mediterranean Sea and should not be eaten. The sea anemone is indeed poisonous, but due to its size, it is not eaten," explains Galil.
According to the article, from 2004 to 2023, 144 poisoning cases were reported from all the countries in the study. The highest number of poisonings was reported from Syria – 64 cases, Turkey reported 24 cases, and Israel, in third place, reported 19 poisonings. The highest number of deaths reported was in Lebanon – 16 cases, and in Israel, a single fatal case was recorded during these years. “The number of deaths reported depends on several factors: the accessibility of fish to consumers, both by non-commercial fishermen and in local fish markets, the choices of local consumers, the accessibility of medical help to victims, and the level of interest of local hospitals and the press in publishing these cases.” In addition to poisonings resulting from food, 28 bite incidents were also reported, which occurred mostly during the summer and which, in extreme cases, in Greece and Turkey, even led to amputations.
"It is a large and voracious predator, feeding mainly on crustaceans and cartilaginous fish, including commercially valuable species such as shrimp, sardines and cyprinids. Due to its rapid growth, high reproductive potential and lack of natural predators, it has established large and stable populations independently, mainly in the eastern Mediterranean," she explains.
Galil emphasizes that "in light of the deadly toxicity of the elongated legionnaire, the ministries of agriculture in Cyprus, Egypt, Greece, Lebanon and Turkey have banned fishing and selling this species, and the ministries of agriculture in Tunisia and Italy have launched an extensive information campaign, recruiting national research institutes. Despite its explosiveness along the coast of Israel, the Fisheries Department at the Ministry of Agriculture does not prohibit its marketing and does not warn the public about its danger." The status of the elongated legionnaire remains As a "protected natural value" in the Mediterranean waters of Israel, as part of the Nature and Parks Authority's list of protected species. While the study was mainly concerned with mapping cases in the Eastern Mediterranean countries, it also included Libya and Tunisia, indicating the continued spread of these invasive species in the Mediterranean. The elongated legionnaire has also been observed on the coasts of Spain, AndItaly, where researchers warn of the danger to public health.
What is sepsis migration?
The main source of the phenomenon of invasive species in the Mediterranean is the Suez Canal, which changed the marine landscape of the eastern Mediterranean. Invasive species began to migrate into the Mediterranean after the opening of the canal in 1869, a phenomenon which intensified after the canal was widened in 2015This migration, or rather the mass invasion of species into the Middle East, was named after the initiator of the canal. Ferdinand de Lesseps, and it is called the "Lessepian migration". De Lesseps never knew to what extent the canal had reached, about its expansion and the intensive trade through it, and how it affected human health. More than 400 species migrated to us through the Suez Canal. The elongated legionnaire and the sea-sophisticated wrasse are examples of poisonous species, but along with them came venomous species. Prominent examples are The migratory thread jellyfish, not a few of us have experienced burning from it during the migration season, And the fish of the sea Decorated with spectacular and poisonous thorns.
Invasive species can cause the extinction of native plants and animals, compete with native organisms for limited resources, and alter habitats. The responsibility for dealing with invasive species lies with government authorities such as the Ministry of Agriculture and the Ministry of Environmental Protection, the Nature and Parks Authority, and local authorities, whose role is to address the phenomenon, all the more so when it involves a dangerous species whose negative effects cannot be ignored. "Health hazards to humans from invasive species such as venomous fish, jellyfish, and sea urchins are expected to worsen, and decision-makers need to recognize this and prepare to deal with them. Israel must legislate, implement, and strictly enforce a ban on the marketing and consumption of venomous and poisonous fish species, combined with educating medical teams, people in the tourism and marine recreation industries, as well as the general public, about the dangers of venomous and poisonous species," she concludes.
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