Japanese eel | |
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Scientific classification | |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Actinopterygii |
Order: | Anguilliformes |
Family: | Anguillidae |
Genus: | Anguilla |
Species: | A. japonica |
Binomial name | |
Anguilla japonica Temminck & Schlegel, 1846 |
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Synonyms | |
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The Japanese eel (Anguilla japonica; Japanese: 日本鰻 nihon'unagi) is a species of anguillid eel found in Japan, Korea, China, Taiwan, and Vietnam, as well as the northern Philippines. Like all the eels of the genus Anguilla and the family Anguillidae, it is catadromous, meaning it spawns in the sea, but lives parts of its life in fresh water. The spawning area of this species is in the North Equatorial Current in the western North Pacific to the west of the Mariana Islands. The larvae are called and are carried westward by the North Equatorial Current and then northward by the Kuroshio Current to East Asia, where they live in rivers, lakes, and estuaries. The Japanese eel is an important food fish in East Asia, where it is raised in aquaculture ponds in most countries in the region. In Japan, where they are called unagi, they are an important part of the food culture, with many restaurants serving grilled eel, which is called kabayaki. Eels also have uses in Chinese medicine.
The Japanese eel and other anguillid eels live in fresh water and estuaries where they feed and grow as yellow eels for a number of years before they begin to mature and become silver eels. The silver eels then migrate out of fresh water into the ocean and start their long journey to their spawning area. Adult Japanese eels migrate thousands of kilometers from freshwater rivers in East Asia to their spawning area without feeding. The spawning area of this species was discovered in 1991 by collecting small leptocephali about 10 mm in size, and then in 2005 the same team of Japanese scientists at the University of Tokyo found a more precise location of spawning based on genetically identified specimens of newly hatched preleptocephali only 2 to 5 days old in a small area near the Suruga Seamount to the west of the Mariana Islands (14–17° N, 142–143° E). In more recent years, more preleptocephali have been collected, and even Japanese eel eggs have been collected and genetically identified at sea on the research vessel. The collections of eggs and recently hatched larvae have been made along the western side of the seamount chain of the West Mariana Ridge. Furthermore, mature adults of the Japanese eel and giant mottled eel were captured using large midwater trawls in 2008 by Japanese scientists at the Fisheries Research Agency. The adults of the Japanese eel appear to spawn in the upper few hundred meters of the ocean based on the recent catches of their spawning adults, eggs, and newly hatched larvae. The timing of catches of eggs and larvae and the ages of larger larvae have shown that Japanese eels only spawn during the few days just before the new moon period of each month of their spawning season.