The the natural balance. The history of the

Seto Inland Sea (SIS), in Japan, is surrounded by Honshu, Shikoku and Kyushu

Japanese it is called Setonaikai. There are about 3,000 islands, but only some
are inhabited. About one quarter of all the Japanese inhabitants, 35 million,
live in the area surrounding this body of water. The SIS is made up of seven
bodies of water: Osaka Bay, Harima Nada, Besen Seto Higashi, Hiuchi-Nada,
Hiroshima Bay, Iyo-Nada and Suo-Nada.

bodies of water have two channels that connect them, and eventually they empty
into the Pacific Ocean. (Miller, 2010) The entire area of the SIS covers 14,
420 square miles. This area has a lot of beautiful coastline and scenery and in
1934 it was made a national park in Japan. (Irizuki, 2011)  In its current state it does not seem very
healthy considering its use as a sewage area as well as fisheries. These waters
have changed during the last fifty years, due to human disturbance to the
natural balance.

            The history of the Seto Inland Sea
is that it is one of the oldest trading routes by sea in Japan, and continues
to be used for shipping today. As early as the 1500s, some seafarers had tide
tables of the area. The tide tables helped them determine the high and low
tides for shipping. Philipp Franz Balthasar von Siebold and Thomas Cook
observed this area during the end of the Edo period and observed the natural
beauty of this area. (Shikoku, 2016)  During
the Edo period, many daimyos, feudal lords, used the Seto Island Sea to travel
back and forth from Edo. Several battles took place on the islands of the SIS.
In the 1100s, the Battle of Dan-nu-ura took place in the strait between Honshu
and Kyushu. The Genji clan beat the Heike clan, almost decimating the Heike
clan. In the 1500s, there was a battle between the Mori and Ouichi clan, and
the Mori clan took over the southern part of Honshu. In the 1700s, citizens who
did not want foreigners in their waters started shooting Dutch ships that were
passing through the waterway. (Bennett, 2012) Murakami pirates, who were more
like the SIS navy, began rule of the sea in the late 14th century which
lasted until 1868. The Seto Inland Sea was a major thoroughfare and these
pirates acted as more of a security force, and helped ships navigate through
the passages. They gained a lot of wealth through their endeavors because they
helped the ships make a safe passage through the SIS. (Shikoku, 2016)

            For almost one hundred years, the
island of Nagashima housed two sanatoriums of isolation for individuals with
leprosy. This is another black mark on Japanese history. They were placed there
to separate them from the general population using the water as a barrier. There
were thirteen sanatoriums throughout Japanese islands during this time period. Currently
there are several historical buildings from this time period that are left on
the island which is located in the Seto Inland Sea. The isolation policy ended
in 1996 after having housed over 3,000 patients on the two sanatoriums in
Nagashima. (Move, 2013)

            A ship used in WWII was built in the
naval yard near Hiroshima. This ship named Yamato, was the flagship for Japan’s
navy and was at the Battle of Midway. The United States forces sunk it when it
was on its way to Okinawa. (Bennett, 2012) The shipbuilding industry around the
Seto Inland Sea became more globalized after the 1980s recession. There were
already shipbuilding companies in the SIS, but others moved there in order to
continue operations.

            The Seto Inland Sea area has a
conducive amount of rainfall between May and September to be an optimal grape
growing location in Japan. In 1968, a national institute opened a location on
Hiroshima for grape breeding. (Yamada, 2016)

            The waters of the Seto Inland Sea
were known for the coastal fisheries, which were quickly expanding before WWII.
After WWII, many industrial factories were built around the SIS because of its
good travel waterways, mild climate, lower rate of natural disasters, and due
to shallow waters land reclamation was economically feasible. These factories
began dumping waste into the SIS. Water pollution lowered the fish harvest between
1955 and 1965 due to the dumping by these factories. (Yanagi, 2013) ” Human
activities caused intensive organic contamination, shortage of oxygen in the
water, heavy metal pollution, eutrophication, and red tides in the Seto Inland
Sea” (Irizuki, 2011). Eutrophication is an excess of certain nutrients, usually
phosphates that can cause the rapid growth of algae which leads to lowering the
oxygen level in the waters. This is known as hypoxia. However, in severe cases
it is then known as anoxia, meaning the absence of oxygen, which is a clear
threat to the survival of sea life. The red tides cause hypoxic conditions at
the bottom of the water and this can kill fish. Red tides are the algae bloom
that take on a red or brown color. These algae lead to a large decline in the
aquatic population. (Takahashi, 2009)  During
the 1970s, the amount of red tides went up drastically, reaching 300
occurrences in 1976. However, the incidences did decrease over the following
decades from 200 in the 1980s, and 100 after the 1990s. (Duraiappah, 2012)  Japan established the Environmental Agency in
1971 to limit and cease production of certain chemicals that were dumped into
the water. (Okaichi and Yanagi, 1997) Due to negative environmental issues,
several aquatic species were seen to decline beginning in the 1960s. In a part
of the SIS called Kasaoka Bay, before WWII, the Japanese horseshoe crab was
already a protected species and by 1985 they couldn’t even find their eggs. The
Japanese horseshoe crab was classified as an endangered species in 1994.  The finless porpoise of the SIS is said to be
an indicator of the ecosystem and the heavy decline of this species shows the
relatively poor condition of the food chain. It is also an endangered species.
(Duraiappah, 2012)

            The Hiroshima Bay is well known for
their oyster farming. Because of the large amount of plankton created by a
large amount of nutrients in the water, oysters flourish because plankton is
their food source. (Duraiappah, 2012).There is currently about 30,000 pounds of
oysters produced each year, and to help with the economy about 80% of the
oysters are exported to other countries. Due to the large quantity of oysters,
pearls are also part of the aquaculture of the Seto Inland Sea and this helps
the economy.

            Not only were factories built, but
oil was found around the SIS and in the 1970s the oil production was 1,860,000
barrels a day. The area also produced iron in excess of 50,000,000 tons a year.
(Okaichi and Yanagi, 1997) Oil spills have also contaminated the waters in the
SIS. In 2008, a fisherman first spotted a crude oil spill, and because of his
fast action they were able to shut down the facility where a pipe had
deteriorated in a storage facility in about 3 hours. The Japanese Coast Guard
cast floating barriers in the Bay of Tokuyama within the SIS and were able to
eventually clean it up. (Japanese, 2008) Ocean pollution is difficult to
monitor but birds are a good source because they travel over more areas to
forage for food. Birds who were foraging in the SIS were found to have persistent
organic pollutants (POPs), which help the scientists gather information. (Ito,


            Fishing is an essential part of
keeping the Seto Inland Sea healthy. It is in the best interest of the
fisherman, because it is their livelihood that the conservation is so
important. “The coastal sea without the fishermen, who continue to watch and
conserve it, will be used in a disorderly ­manner by people on land who do not
understand the characteristics of the coastal sea” (Yanagi, 2013) Although the
population in the SIS area is so large, fisherman comprise only .3% of the
population or approximately 30,000 people. With their numbers so low and not
having the impact needed for the conservation, it is important to note that
there are several organizations, such as the Association of the Seto Inland Sea
Conservation which was funded by a local insurance company that educates people
in the area about the environment. This concept was introduced to the Japanese
in 2008 as “Satoumi, which means “Coastal sea with high biodiversity and productivity
under human interaction” (Yanagi, 2013). In 1999, fishing industry in the SIS
brought in $1,100 million. The amount of fish in the area depends on the
ecology of the waters during a time period. Depending on the level of eutrophication,
the waters can have more abundant supplies of anchovies, which helps the fish
population, or jellyfish. When the jellyfish are in abundance, which occurred
after 1990, the amount of fish diminishes. There needs to be management of the
fisheries because, “A large quantity of small immature fishes is usually caught
in the Seto Inland Sea, resulting in growth and/or recruitment overfishing for
many species” (Nagai, 2003). This will lead to lower eutrophication levels, so
there will be more anchovies and less jellyfish.

            Whales are rarely seen in the waters
of the Seto Inland Sea today. These waters used to be feeding grounds for
whales. However, large whaling operations depleted the number of whales, along
with the pollution which made the water difficult for whales to survive in.

            Another area that changed the ecosystem
of the Seto Inland Sea is sea sand collection. This sand was used as fine
aggregate in order to make cement. Records dated back to 1968 up until 2006
when it was stopped, showed the amounts that were collected. Unfortunately,
what this did is to cause coastline erosion, loss of seaweed beds, and modified
currents. This permanently changed the ecosystem. (Duraiappah, 2012).

            Beginning in 1982, the people of
Iwaishima Island in the SIS have been refusing to allow a nuclear power plant
to be built near their homes. This had been going on for over thirty years. The
reason they do not want this built is because they are afraid to lose their
fishing area. Another area that was being looked at for the nuclear power plant
was Kaminoseki which is on Nagashima Island. The residents protested and
managed to put off the project, but the Japanese government approved it to
begin building in 2001. However, the citizens refused to sell their land, and
the fisherman refused to accept money in exchange for the possibility of their
loss of fishing ability. After the Fukushima disaster in 2011, which was caused
by natural disasters, the government suspended the construction of the project.
The citizens saved their waters and it is a known biodiversity hotspot. This
means that there is a large variety of plants and animals. (Ankei, 2012)

            In 1999, a study had been done by
the company who was going to build the nuclear power plant, and it was found to
be inaccurate. They disregarded the endangered species in their report. Despite
the pollution in the waters near Nagashima, it still continues to be a
biodiversity hotspot. When an NGO, called The Association for the Conservation
for Nagashima Island, got involved, they found many species that were either new
or endangered. Nagashima has somehow managed to retain 75% of its natural
shoreline, whereas most other areas did not due to economic development. (Ankei,

            There have been studies that the Philippine
Sea Plate leads to areas under the Seto Inland Sea and has caused earthquakes
that are 50-70 km below the area of the SIS side of the island of Hiroshima. There
were two earthquakes that occurred in the Western Seto Inland Sea, in 1968 and 1979)
that were deeper than what usually occurs. This is caused by the subduction of
the plate under the SIS. The subduction zone is when one tectonic plate slides
under another tectonic plate. (Nakanishi, 2002)

            Due to the flow of water toward the
Pacific Ocean through the Straits, the tide and their currents are very strong
in the Seto Inland Sea. This has a powerful influence on the coastal
environment. The studies on tsunamis and tides are important so disaster is possibly
prevented, where lives are saved and the coastline is protected. The tests that
are undertaken are important so the tides and tsunamis’ behavior can be possibly
determined before they happen. (Lee, 2015) There may be some places around the
Seto Inland Sea that may be affected by high tides caused by global warming,
especially because it is an enclosed area where the tides do not have as much
space to dissipate as they would in a vast ocean. Flooding occurs on the coast
of SIS when cyclone type weather increases the storm surges and global warming
impact could cause these type of great floods. Global warming is continuing and
the land areas that were reclaimed around the Seto Inland Sea will be at great
risk of high tide flooding. For example, in 2004 Typhoon Chaba which was a
tropical cyclone, occurred at the height of high tide, destroying thousands of
homes and killing thirteen people due to the storm surges which occurred in the
west end of the SIS. However, in 1991 strong storm surges occurred but did not create
any disaster because it was during the low tide. The direction of the wind is
also a factor as to how high the surge is and the devastation that can occur. (Kamakuro,

            In order to increase the economy in
the Seto Inland Sea area, in 2009 the Japanese government turned ferries that
were used to travel to the different islands into ships for cruising. The ferry
operators were affected economically because of rising costs of fuel and the
fall in the economy during this time period. (Japan, 2009) Today, there are
many tourist attractions that help the economy in this area. In Okayama, on
Honshu, there is a beautiful landscape that dates back to the 18th
century. People visit the Peace Memorial Museum in commemoration of the
devastation of the atomic bomb in Hiroshima during WWII. On the island of Miyajima,
people visit the Shinto shrine, Itsukushima Jinja.

            The ability to increase tourism came
about when a series of bridges were built over the Seto Inland Sea. These are
both auto and rail bridges and are known as Seto Ohashi in Japanese, and its
literal translation is the Seto Great Bridge. There are six bridges in total
with a combined length of about 23 miles. Previously, before the bridges were built,
people had to be transported on ferries, which took about an hour. These
ferries sometimes got cancelled due to weather conditions. The bridges allow
the traveler to reach their destination in just ten minutes. In the ten years
to build the Seto bridges, it cost $9.2 billion. The Minami Bizan Seto is a
suspension bridge that can be compared to the San Francisco Golden Gate Bridge.
The Minami Bizan Seto has a span of about 3,600 feet, as compared to the Golden
Gate which has a 4,200 foot span. These bridges were built not only to increase
tourism but to also increase investments on the islands. No longer was the
water a challenge in this regard. (Oka, 1988)

            The Seto Inland Sea is a very important area of Japan that
houses a large number of the population. The fishing and tourism industries are
the main sources of income, and these waters are very important to their


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