Alien species of young eels were imported to Japan in February, including some from Madagascar, recent trade data compiled by the Finance Ministry shows, the first time that imports of African eels have been confirmed in statistics.
If species different from Japanese eels have been traded in Japan, partly due to extremely poor catches of young Japanese eels for three years in a row, it could spark concerns about the spread of alien eels in the domestic ecology of the fish.
"If alien species of grown eels establish a habitat after escaping or being let go in streams, it could have a bad impact on the already serious conditions for Japanese eels," said Jun Aoyama of the University of Tokyo's Atmosphere and Ocean Research Institute.
The data showed that in February, 30 kg of young eels were imported from Madagascar, as was 50 kg from the Philippines.
When catches of young eels were poor in the past, European and American varieties of young eels were imported to be raised at fish farms, according to experts.
European eels have previously been let go in streams to maintain the fish's population in Japan and have since been found establishing a habitat near the country.
