Around Tokyo...
Enigmas
Mostly enigmas in life are from minds of people in a family, neighbors, or society.
However, to increase one's own enigmas inside might not be so recommended.
Yet, Christ Jesus said not to inform others on the left hand side of what you are doing with the right hand.
1. Eels
The Japanese people like to eat eels, especially, in the summer. Grilled eels with a special source on rice are favorites for most of the Japanese.
However, it has been a long mystery where eels were born though they come up swimming to grow in shores, rivers, and ponds of the Japanese Archipelago as well as those in Taiwan and the Korean Peninsula.
(Some Japanese personally capture eels in rivers nearby or so [proper fishing time is from evening to night]...,
http://chikyu-no-cocolo.cocolog-nifty.com/blog/2009/06/post-21b3.html?page=3)
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On the other hand, it was found in 1922 that the European eels were born in the Sargasso Sea of the Atlantic Ocean as with the North American eels.
Eels are believed to have been created in the sea between the presently Malay Peninsula and Borneo island. When India was not attached to the Eurasia continent 100 million years ago, the Indian Ocean and the Atlantic Ocean were directly connected. In two different periods of time in history, eels are believed to have traveled from Asia to Europe and the Atlantic. Probably, the first migration led to establishment of the North American eels and the second migration the European eels, since subsequently the Atlantic Ocean came to be separated from the Indian Ocean through the Mediterranean Sea and the Arabian Peninsula.
What is unbelievable is that both the North American eels and the European eels hatched in the Sargasso Sea of the Atlantic Ocean. But, juvenile fish moved and grew around the Bermuda islands. Then, the North American eels swim to North America and the European eels travel to Europe. They spend most of their life time at each destination of the two continents and then come back to the the Sargasso Sea for propagation.
This is a big mystery, since there seems to be no confusion about locations to go to and come back to for American and European eels, respectively. It is said no North American eels move to Europe and no European eels to North America from the sea around Bermuda.
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Now, it was still a mystery where the Japanese eels laid their eggs. However, very recently, Japanese researchers have confirmed that it is around Guam. In May 2009, they caught 31 eggs of eels in the West Mariana oceanic ridge near Guam island some 2200 km south of Japan at a depth about 200 meters of the South Pacific Ocean. A gene analysis confirmed that they were eggs of the Japanese eels.
- A juvenile fish of the eel is called an elver weighing 0.2 grams.
- Japan harvested elvers (for fish breeding) in a yearly total weight of 200 tons at coves and river estuaries in 1960's.
- A grown-up eels weighs about 250 grams.
- Japan harvested in a yearly total of 2500 tons of grown-up eels in 1960's.
- One female eel lays one million to five million eggs.
From these data, 1 billion elvers and 10 million grown-up eels were captured every year in 1960's when rich harvests were observed. But, if one female eel laid 2.5 million eggs, only 404 female eels were needed for all the elvers and grown-up eels that were taken in Japan.
However, the probability of elvers might be one in 10,000. So then, it needed 404 million female eels only for all the elvers and grown-up eels that were captured in Japan.
But, how can eels sustain their reproduction while more than one billion individuals were taken in Japan which never returned to the spawning region around Guam? As a matter of fact, harvests of elvers and grown-up eels have drastically fallen in these decades.
In the above figure, the green graph stands for catches of elvers; the orange stands for that of grown-up eels.
Anyway, the above figure proves that eels returning from Japan to the spawning region around Guam have contributed in a large proportion to propagation of eels. So, the enigma remains: how can they return to their birth place in the South Pacific Ocean 2200 kilometers far from the Japanese Archipelago?
But, the answer might be in timing of elvers reaching Japan and grown-up eels swim down rivers to the Pacific Ocean. When elvers are flowing to Japan in autumn catching the Kurosio Current (Black Stream), grown-up eels start to return to the spawning sea area in the South Pacific Ocean.
Accordingly, they should meet one another in the sea around Japan. All the grown-ups have to do is just take a course on which they meet elvers coming one after another, riding on the tide or current around Japan. In a path under the ocean, two streams are passing each other: one for elvers to Japan and another for grown-up eels to the Mariana oceanic ridge. So, the grown-up eels do not take a straight line from Japan to the spawning site but just trace the greatly warped Kurosio Current backward from the mainland Japan to Okinawa and Taiwan and then to north of the Philippines and to Guam. This is my answer to the enigma of centuries.
http://shimura.moo.jp/osakana1/jyouhou7.htm)
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Finally eels might be going extinct. The amount of elvers as natural resources is so sharply decreasing in Japan, North America, and Europe. The above graphs show change in the amount. So, complete cultivation of eels, namely from eggs to grownups through elvers, are actively pursued in Japan.
Yet Japanese scientists and researchers are making full efforts to cultivate eels from eggs to grown-ups through elvers in an aquarium. They found that young elvers eat eggs of spiny dogfish. So, on a study base, they have achieved complete cultivation from eggs to grownups. But an aquarium must be kept clean and other cares are needed. It requires big costs. It takes $1000 or so to grow one eel.
Japan succeeds in world's first complete cultivation of eels
Kyodo News Saturday, April 10, 2010
A government research organization has succeeded in breeding second-generation cultivated eels for the first time in the world by using sperm and eggs collected from those artificially raised from eggs, it said Thursday.
The achievement by the Fisheries Research Agency in Yokohama could be the first step toward securing eel resources, following a 90 percent plunge in catches over the last 30 years.
The current cultivation system requires catching glass eels, or juvenile eels, and raising them, but a branch of the research agency succeeded in raising glass eels from artificially bred larval fish in 2002, also for the first time in the world.
After these glass eels became 45 cm to 70 cm long, the agency gave them hormones to stimulate sexual maturation to extract sperm and eggs earlier this year, and succeeded in getting some 250,000 fertile eggs on March 26 through artificial insemination.
Some of them hatched the following day and are now growing thanks to feedings by the researchers since April 2, according to the organization.
The development of the full cultivation of eels could help protect natural eel resources and increase the success rate of artificial breeding by using eels that are more adapted to the artificial environment, the researchers said.
http://www.japantimes.co.jp/text/nn20100410b6.html
Glass Eels - Credit: NY Dept of Environmental Conservation
APPENDIX 1. Traditional Eel Hunting in Japan
Japanese people have a long history of capturing and eating eels. The following picture shows the practice 200 years ago.
APPENDIX 2. Where in the World Eels Live
Though the following picture does not indicate, Vietnamese also capture eels in their rice fields.
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Next Monday on July 18 is a public holiday in Japan.
On the other hand, the final of the Female World Cup Soccer, namely Japan vs. the U.S., is to start about 3 a.m. of Monday, Japan Time.
So, this Sunday night, everyone in Japan is going to keep vigil and watch a live broadcasting of the match from Frankfurt, Germany.
By the way, there is one interesting report on this sport:
In June 2011 Iran forfeited an Olympic qualification match in Jordan, after trying to take to the field in hijabs and full body suits. FIFA awarded a default 3–0 win to Jordan, explaining that the Iranian kits were "an infringement of the Laws of the Game", due to safety concerns.[9] The decision provoked strong criticism from Mahmoud Ahmadinejad[10] while Iranian officials alleged that the actions of the Bahraini match delegate had been politically motivated.
http://en.wikipedia.org/wiki/Women%27s_association_football