Eel
Anguilla anguilla (Linnaeus, 1758)
Order: Anguilliformes
Family:Anguillidae
Enguia, eiró, meixão, loura, glass enguia
eel, eel, glass eel
Eel, glass eel
The eel is a demersal species, euryhaline andcatadromous(it is born in the sea and grow, mainly, in the river). The larvae are supposed to hatch in the Sargasso Sea and then, transported by ocean currents, reach Europe and North Africa. In the Miño river, the entrance of the glass eel (5-8 cm) (eel) occurs throughout the year, although the greatest flow occurs between October and May. After entering the river, some remain in the estuary while others move upstream. After pigmentation, it is calledyellow eeland, after a few years, undergoes a new transformation to thesilver eel(the eyes enlarge, as well as the pectoral fins, and taking on a silver hue on the belly) preparing for the journey to great depths to the breeding site, where they die.
Morphology
Serpentine body. Mandible slightly prominent in relation to the maxilla. Dorsal fin insertion closer to anal fin insertion than to eyes. Intradermal scales that give the appearance of smooth skin. It has between 110-120 vertebrae. Fins without rays. Dorsal, caudal and anal fins continuous. Absence of ventral fins. Well developed lateral line. Grayish color on the back and lighter on the belly that acquires a silvery appearance in sexual maturation, increasing the size of the eyes. There are no similar species in fresh water.
Adulto
Adulto
Parasito Anguillicola crassus
Adulto
biology
Speciescatadromous, demersal and euryhaline. ​The life cycle is complex and not yet fully understood.
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They are proven to perform extraordinary migrations. The adults, taking advantage of ocean currents, migrate to the Sargasso Sea due to the exceptional conditions found there (4,000-7,000 km away from various points in Europe and North Africa). The duration of this trip is estimated at 6 months.
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In the Sargasso Sea,no eel ready to lay has ever been found, not even eel eggs, only larvae 3-4 mm. It is assumed that at great depths the reproductive eels, called silver eels, carry out the postures, originating eel larvae orleptocephali, transparent, leaf-shaped beings that migrate into European waters. Before entering estuaries, leptocephali undergo a metamorphosis that profoundly affects morphology and physiology, eventually becoming transparent eels (eels or meixões), eel-like beings.
After the rise of the inland waterways, the glass eel develops en yellow eel, a phase that lasts approximately 4 years for males and 7 years for females. After this period, which develops in fresh water, they undergo a new transformation to breeding eel (silver eel), prepared for the migration back to the Sargasso Sea. There are individuals that remain in the marine environment for the entire period of their lives.
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In the Miño River, the entry is made throughout the year, however, the time when this occurs with the highest incidence is between October and May. They arrive with a length that ranges between 5 and 8 cm. On their migration upstream they sometimes have to overcome serious obstacles.
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Individuals with 14 kg and a maximum age of 85 years are described. Males can reach about 50 cm, while females can reach about 150 cm. In the Miño River, food is diverse depending on the habitat. In the initial zone of the estuary they feed preferably on crustaceans while upstream they feed on gastropods and fish.
Distribution
The eel is widespread in Europe and North Africa, but the progressive construction of dams and the absence of upstream passages lead to a loss of habitat for the species, which translates into fewer adults with reproductive capacity. On the other hand, although they manage to climb and pass the dams, many eels die passing through the turbines in the descent of the rivers.
Conservation
Species indigenous. It is a species that is in regression. It lost its habitat due to the construction of dams. Affected by water quality and parasites, in particularAnguillicoloides crassus, also present in the eel population of the Miño river. Their presence upstream of the Miño river dams is due to the voluntary transposition of glass eels by associative groups.
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-Red Book of Vertebrates of Spain​: (V) Vulnerable
-Livro Vermelho dos Vertebrados de Portugal: (EN) Em perigo
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In most European rivers, from the 1980s onwards, there has been a trend of declining catches of glass eels. Therefore, the stock of the eel population must be discussed at the European level and conservation and protection measures must be taken together.
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The European Union has legislated to require all countries to submit their management plans for their river basins, and several countries have since banned the capture of eel and yellow eel.
Fishing
High commercial importance, especially in the elver phase.
It is a commercially exploited species in all stages of the life cycle, except in the larval stage.
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In Portugal, this resource is little appreciated gastronomically, unlike in Spain. Eel-based dishes are highly valued in Japan, which is why a large percentage of eel caught in European rivers is illegally sent to aquaculture in the East. However, due to the demand for this product for export, the value per kg of eel caught in the Miño River is quite high, reaching up to €500/kg.
The Miño River is the only river in Portugal and Galicia where the capture of elver is still allowed.The catch of glass eels has decreased sharply since the mid-1980s.​
In the past, the eel was consumed by the people of the riverside, who were sold door to door. When its economic value increased, it was almost completely sold to Spain, where there is a strong tradition in its consumption. While at first the eel was fished with a ganapán, mainly on the riverbank, from the 1970s a net was born in the Miño River to capture it:the cloth.