To conserve eel―Reasons for the declining

To understand why volume of amount of eel catch keeps declining. We went to the Atmosphere and Ocean Research Institute of Tokyo University.

To conserve eel

Reasons for the declining


・There are mainly 3 reasons.
 1 Climate change
 2 Habitat degradation
 3 Excess fishing
・Everyone has a great responsibility for the decline.

The increased price, caused by the decline in eel catch, was said to be one of most important factors lead to the crisis of traditional Japanese food culture.
We went to Atmosphere and Ocean Research Institute, The University of Tokyo and we heard the reason why eel catch is declining.
to Atmosphere and Ocean Research Institute, The University of Tokyo

 Taken by people involved in this labo

①Climate change
El nino has a great influence on this problem. According to previous research, Japanese eel spawns near Guam and later on emerged into leptocephalus. Usually, those eel swims from latitude 14°N to Japan. They use the branching point of the Kuroshio and the Mindanao Current from North Equatorial Current as a mark. However, due to the El nino, the mark flows to the south which will lead the eel swim to the south instead of north and, in most of the cases, lost their lives.

See the illustrations for more details.
Usual       El nino
     <Usual>                   <El nino>

We assume global warming is one of the reasons for this problem. However, according to Dr.Kimura, the cause for this problem is still under investigation.

②Habitat degradation
Eels lay eggs in the sea then run up to the river. However, recently due to the concrete bank protection of the river, the food for young eels such as earthworms, mayflies and so on is difficult to find. Thus, we can tell concrete bank protection may protect the river in some degree but has destroyed earthworms' habitat in which way leading to a difficult situation for the growth of young eel.
Previous research also indicated that the rate of eels' growing up is inversely related with the rate of concrete bank protection.
Although a FISH WAY was set up with the consideration of the listed situation, for now there is no water in the fish way.

③Excess fishing
The cultivated eels that we eat are breeded from Shirasu which catches in the nature. Recently, some fisher for their own interests, ignore rules and overfish. As a result, eel declined significantly.

Climate change is the laws of nature and to improve the situation of habitat costs a large amount of money, therefore ① and ② may be too difficult for senior high school students to solve. Meanwhile, as consumer, we have the responsibility and ability to make our own contribution to excess fishing.

The responsibility of excess fishing not only lies in fishers but also in us.

How do we protect eels?