ENVIRONMENTAL CONSERVATION
OF THE SETO INLAND SEAInternational EMECS Center

EEN
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MEEN
NTTA
ALL CCOCONTENTSPREFACE

LIST OF CONTRIBUTORS

1．OUTLINE OF THE SETO INLAND SEA（ Tetsuo YANAGI ）1.1 OUTLINE

2

1.2 WEATHER AND SEA CONDITIONS

5

1.3 TRANSITION OF POPULATION

6

1.4 THE ENVIRONMENT

8

1.5 FISH PRODUCTION

16

2．CHANGES IN THE ENVIRONMENT IN THE SETO INLAND SEA
2.1 INDUSTRIAL AND HUMAN ACTIVITIES

20（ Tsunekazu TODA ）2.2 NEGATIVE LOAD ON THE ENVIRONMENT

27（ Tsunekazu TODA ）2.3 CHANGES IN WATER AND SEDIMENT QUALITY

33（ Kuninao TADA ）2.4 OCCURRENCE OF RED TIDES

45（ Ichiro IMAI ）2.5 MARINE POLLUTION FROM OIL SPILLS AND OTHER CAUSES

55（ Ichiro IMAI ）3．MEASURES FOR THE CONSERVATION OF THE ENVIRONMENT OF THE SETO
INLAND SEA（ Kuninao TADA ）3.1 MEASURES FOR THE CONSERVATION OF ENCLOSED COASTAL SEAS

62

3.2 MEASURES AND STRATEGIES BASED ON THE SPECIAL LAW FOR THE

64

CONSERVATION OF THE ENVIRONMENT OF THE SETO INLAND SEA
3.3 PROMOTION OF PREFECTURAL PLANS FOR CONSERVATION OF

66

THE SETO INLAND SEA
3.4 PERMISSION FOR THE INSTALLATION OF SPECIFIED FACILITIES

66

3.5 TRANSITION OF THE TOTAL AMOUNT OF POLLUTANTS LOADED66

3.6 POLLUTANT LOADS AND THEIR CONCENTRATION68

IN SURFACE WATER IN THE SETO INLAND SEA
3.7 DESIGNATION OF NATURAL SEASHORE

72

CONSERVATION AREAS
3.8 REGIONAL ENVIRONMENTAL POLLUTION CONTROL PROGRAM

73

3.9 CONSTRUCTION AND IMPROVEMENT OF SEWERAGE AND

73

OTHER SYSTEMS
3.10 CONSTRUCTION OF SOLID WASTE TREATMENT AND

75

OTHER FACILITIES
3.11 CONSTRUCTION OF WASTE OIL TREATMENT AND OTHER FACILITIES

76

3.12 RESTRICTIONS BASED ON THE LAW CONCERNING SPECIAL MEASURES76

FOR CONSERVATION OF THE ENVIRONMENT OF THE SETO INLAND SEA

4．FUTURE TASKS AND CHALLENGES FACING THE SETO INLAND SEA( Tetsuo YANAGI )4.1 NEW ENVIRONMENTAL POLICIES

80

4.2 POSSIBLE IMPROVEMENT IN HABITAT CONDITIONS AND

80

LIVING RESOURCES
4.3 SOME CASES OF ENVIRONMENTAL RESTORATION80

IN THE SETO INLAND SEA
4.4 FUTURE DIRECTIONS

5．REFERENCE

81

84

6．APPENDIX
6.1 CONTROL LAW SYSTEM IN A COASTAL ZONE

90

6.2 ENVIRONMENTAL CHRONOLOGY OF JAPAN91

6.3 AREA-WIDE TOTAL WATER POLLUTANT LOAD CONTROL93

SCHEME FOR ENCLOSED COASTAL SEAS IN JAPAN ;PROGRESS AND FUTURE DIRECTION
6.4 MEASURES TO PREVENT EUTROPHICATION IN ENCLOSED102

COASTAL SEA
6.5 LAW CONCERNING SPECIAL MEASURES FOR CONSERVATION OF THE

104

ENVIRONMENT OF THE SETOINLAND SEA
6.6 BASIC ACT ON OCEAN POLICY114

PREFACE
Enclosed and semi-enclosed coastal sea areas, such as bays, inland seas, and estuaries
have provided human beings with ideal places for fishing, industry, marine traffic, andrecreational activities. They have also supported the livelihood of residents in the coastal
area and fostered various cultures.
Due to their characteristic features of having limited seawater exchange with open
water and the inflow of pollutants from coastal areas, the environments of enclosed andsemi-enclosed coastal seas have become consistently degraded, and the number of species
and their populations have been reduced. Now, there is concern that the scale of theenvironmental degradation has become so great that it is going to have serious impacts
on the global environment.
In the areas of the Seto Inland Sea, the largest enclosed coastal sea in Japan, thewater environment has deteriorated in relation to economic growth. In order to tackle
this problem and keep the natural environment beautiful for future generations, various
entities such as local governments, companies, NGOs and citizens are working hard together for the sake of the environment. Collaboration can be promoted by sharing informationon the Seto Inland Sea: information not only on the environment, but also society, theeconomy and culture.
This book, "Environmental Conservation of the Seto Inland Sea", is intended to beshared by various actors in the world. It is expected that information exchange will growfrom the coastal areas of the Seto Inland Sea and contribute to the conservation of the
global environment.
The project to publish the book was accredited as a "project for global environmental
conservation in 2007" by the Japan Post Service Co., Ltd. and received financial support
from them. The Association for the Environmental Conservation of the Seto Inland Sea
kindly provided us with valuable data and information.
In closing, we would like to thank all our contributors, who have worked tirelessly
to prepare the manuscripts and edit the book. We appreciate their assistance very much.

International EMECS Center

LIST OF CONTRIBUTORS

Ichiro Imai
Associate Professor, Laboratory of Marine Microbiology
Division of Applied Biosciences
Graduate School of Agriculture, Kyoto University
Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, JAPAN
imai1ro@kais.kyoto-u.ac.jp

Kuninao Tada
Professor, Laboratory of Biological and Chemical Oceanography
Faculty of Agriculture, Kagawa University
Miki, Kagawa 761-0795, JAPANtada@ag.kagawa-u.ac.jp

Tetsuo Yanagi
Professor, Research Institute for Applied Mechanics,
Kyushu University
6-1 Kasuga-Koen Kasuga-shi Fukuoka Pref. 816-8580, JAPANtyanagi@riam.kyushu-u.ac.jp

Tsunekazu Toda
Director of Community Cooperation Center
Professor of Regional Policy, Hiroshima University
1-1-89 Higashi-senda, Naka-ward, Hiroshima City 730-0053, JAPAN
toda@hiroshima-u.ac.jp

Seto Inland Sea scenery

Bird's-eye View of Seto Inland Sea (courtesy of Asia Air Survey Co., Ltd.)

Akashi-Kaikyo Bridge (HP:Honshu-Shikoku Bridge Expressway Company Limited)

Osaka Port

Seto Inland Sea scenery

Siaku Islands (Kagawa Pref.)Itsukushima Shrine (Hiroshima Pref.)Seaweed Bed (Yura, Awaji Island)

Seaweed Bed (Yura, Awaji Island)

Tidal Flat (Ushimado, Okayama Pref.)Tidal Flat (Kamagari, Kure City)

Seto Inland Sea scenery

Fishing boat (Himeji City)

Oyster Bed (Hiroshima Pref.)Quarry (Himeji City)

Red Tide (Awaji Island)Blue Tide (Amagasaki Port)Chapter 1 OUTLINE OF THE SETO INLAND SEA
1.1

2

OUTLINE

1.2 WEATHER AND SEA CONDITIONS

5

1.3 TRANSITION OF POPULATION

6

1.4 THE ENVIRONMENT

8

1.5 FISH PRODUCTION

16

− 1 −

Chapter1 OUTLINE OF THE SETO INLAND SEA
1.1 OUTLINE
Since ancient times, people have been enjoying the Seto Inland Sea, one of the mostbeautiful seas not only in Japan but also in the world, blessed with its numerous islands, mild
climate, low precipitation and abundant nature. The Seto Inland Sea is the largest semi-enclosed
coastal sea in Japan; it is surrounded by three large islands, Honshu, Kyushu and Shikoku, andhas more than 700 small islands within its area. Its total shoreline is 6,868 km long (Figure 1-1 (a)).
The Seto Inland Sea is about 450 km from east to west and varies from 15 - 55 km north tosouth. It has an area of 23,203 km2 with an average depth of 38.0 m. Accordingly, the volumeof the Seto Inland Sea is about 881.5 km3. The Seto Inland Sea has many large and small
straits, bays and shore reefs. The Kii Channel (in the east) and the Bungo Channel (in thewest) lie between the Seto Inland Sea and the Pacific Ocean, and the Kanmon Strait (in thewest) lies between the Seto Inland Sea and the Japan Sea. The water body and the watershed
area, as defined by the "Law Concerning Special Measures for Conservation of the Environmentof the Seto Inland Sea", are shown in Figure 1-1 (b).

Figure 1-1 (a) Location of the Seto Inland Sea− 2 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Kyoto Pref.
Hyogo Pref.
Osaka
Pref.

Okayama Pref.

Harima-nada

Hiroshima Pref.

Osaka
bay

Nara Pref.

Bisan-seto

Tsunozima-tsuuse Cape
Tokuushi Lighthouse

Bingo-nada
Hiroshima bay

Yamaguchi Pref.
Hinoyamashita
Lighthouse

Aki-nada

Kagawa Pref.
Kii Channel

Hiuchi-nada

Tokushima Pref.

Hibiki-nadaKii Hinomisaki
Lighthouse

Mojizaki Lighthouse
Myokenzaki
Lighthouse

Ehime Pref.

Gamoda Cape

Suo-nada

FukuokaPref.

Wakayama Pref.

Iyo-nada

Sata Cape
Sekizaki Lighthouse

Oita Pref.

Bungo Channel

LegendTsurumi Cape

Boundary among Prefectures

Takamo Cape
0

10

20

30 km

Area of the Seto Inland Sea

Note: Source; The Association for the Environmental Conservation of the Seto Inland Sea

Figure 1-1 (b) Water body and watershed area as defined by the "Law Concerning Special
Measures for Conservation of the Environment of the Seto Inland Sea"

Kyoto Pref.

Hyogo Pref.
Okayama Pref.
Osaka
Pref.
Hiroshima Pref.
Nara
Pref.
Kagawa Pref.

Yamaguchi Pref.

Tokushima Pref.

Wakayama
Pref.

Ehime Pref.
FukuokaPref.
Legend (m)Oita Pref０〜−１０−１０〜−２０−２０〜−４０−４０〜−６０−６０〜−１００−１００〜−２００

0

10

20

−２００〜

30 km

Note: Source; The Association for the Environmental Conservation of the Seto Inland Sea

Figure 1-1 (c) Water depth in the Seto Inland Sea− 3 −Chapter1 OUTLINE OF THE SETO INLAND SEA
In olden times, there existed names of nada (basin) and bays such as Suo Nada andOsaka Bay, but there was no name for the total area of the Seto Inland Sea because people
did not have such a broad viewpoint. People started using the name of the Seto Inland Sea
from around 1882 after foreigners referred to this inland sea as the Seto Inland Sea.
The basic dimensions of the Seto Inland Sea, Tokyo Bay and Ise Bay, which are typicalenclosed coastal seas in Japan, are shown in Table 1-1.
Table 1-1 Basic dimensions of three largest enclosed coastal seas in Japan
Seto Inland Sea
Osaka BayArea of Water Surface (km2)

23,203

Mean Depth (m)Volume (100 million m3)

Tokyo Bay

1,447

1,380

Ise Bay
2,130

38

30

45

17

8,815

440

621

394

30

13

25

10

Population on Watershed (million)

Note: Source; Environment Agency and Ministry of Transport of Japan, and "Tokyo Bay-Transition in 100 years"
edited by Norio Ogura

The dimensions of the sea area and the islands in each prefecture concerned with the
Seto Inland Sea are summarized in Table 1-2 and Table 1-3, respectively.
Table 1-2 Dimensions of the sea area in the Seto Inland Sea
Area(km2)

Name of Straits and Bays

Mean Depth(m)Volume(100million m3)

Kii Channel
Osaka Bay
Harima-Nada
Bisan Strait
Bingo-Nada
Hiuchi-Nada
Aki-Nada
Hiroshima Bay
Iyo-Nada
Suo-Nada
Hibiki-Nada
Bungo Channel

1,938
1,447
3,426
1,063
773
1,619
744
1,043
4,009
3,805
592
2,744

45.8
30.4
25.9
16.3
20.3
24.0
39.9
25.8
55.7
24.1
32.9
71.8

887
440
889
173
157
389
297
269
2,232
917
195
1,970

Seto Inland Sea

23,203

38.0

8,815

Note: Source; Environment Agency of Japan

Table 1-3 Number of islands in each prefecture concerned with the Seto Inland Sea
Prefecture
Hyogo Pref.
Wakayama Pref.
Okayama Pref.
Hiroshima Pref.
Yamaguchi Pref.
Tokushima Pref.
Kagawa Pref.
Ehime Pref.
Fukuoka Pref.
Oita Pref.
Total

Total No. of Islands
57
41
87
142
127
24
112
133
6
3
727

Main Islands

Inhabited islands
15
1
35
77
41
5
56
60
3
14
307

7
0
21
36
23
2
27
32
2
7
157

Note: Source; "SHIMADAS, National Institute For Japanese Islands"

Almost all bays and nadas in the Seto Inland Sea are shallow and less than 60 m indepth except Beppu Bay, Iyo-Nada, Bungo Channel, Kii Channel and Hibiki-Nada (Fig.1-1(c)).

− 4 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

1.2 WEATHER AND SEA CONDITIONS
The region of the Seto Inland Sea is meteorologically referred to as the "Seto Inland
Climate Zone". In this region, the annual average temperature and precipitation are 15 ℃ and
1,000-1,600 mm, respectively. This means that this region is relatively mild in comparison withother regions in Japan. On the other hand, the mountainous areas around the Seto Inland Sea
have high precipitation with an annual rainfall of 2,000-3,000 mm.
The distribution of annual precipitation in the Seto Inland Sea region is shown in Figure
1-2.

1480
1,469

1,528

1,225

Tsuyama

Kyoto

1,247

1333
1,324

1306
1,294
1,139

Himeji

1,150
1,690

1,538
1,420

Hagi
Yamaguchi

1,115

Hiroshima

SumotoTadotsu

Wakayama

Tokushima

1090
1,078

1,300

Shimonoseki

1,792

Nara
Osaka

1,335

Takamatsu
1,550

Kure

Kobe

1,450

Fukuyama

1,887

1,696

Okayama

2,534

2,611

Matsuyama
Iizuka
Kochi

1,827
1,680

2,367
2358

Shionomisaki Cape

1,636

Hita
Oita

Muroto Cape

1,987
1990

Uwajima

2,469

1,000㎜

Sukumo
0

10

20

30 km

Shimizu(Ashizuri)

Note: Source; The Association for the Environmental Conservation of the Seto Inland Sea

Figure 1-2 Distribution of annual precipitation in the Seto Inland Sea area
The amount of water discharged into the Seto Inland Sea from 669 river systems is
as much as 50 billion km3 a year.
Through all seasons, the wind direction in the coastal areas is usually vertical against
the shoreline because a land-sea breeze develops. On the other hand, the wind direction in land
areas largely depends on the geographical features. The wind pattern in the Seto Inland Sea
is characterized by its regularity. The seasonal variation in water temperature and salinity of
the Seto Inland Sea is greater than that of the Pacific Ocean because the condition of the sea
in the Seto Inland Sea is generally affected by the weather conditions.
Through the Kii Channel and the Bungo Channel, water exchanges between the Pacific
Ocean and the Seto Inland Sea, and through the Kanmon Strait water exchanges between theJapan Sea and the Seto Inland Sea. The salinity of the surface layer is less than 32 in Osaka
Bay, about 30-32 in the Bisan Strait, less than 31 in Hiroshima Bay and about 32 in the Kii
channel. These salinity data are lower than in the Bungo Channel, which is about 33.
The tidal current in narrow straits, such as the Naruto and Hayasui Straits, is fastand complex and reaches 5-10 knots. The complex geographical features affect uniquecharacteristics of the tidal current.

− 5 −Chapter1 OUTLINE OF THE SETO INLAND SEA
1.3 TRANSITION OF POPULATION
The watershed-land of the Seto Inland Sea spreads out over about 68,000 km2 as shownin Table 1-4, which corresponds 18 % of the total land area of Japan.
Table 1-4 Populations and land areas of the prefectures located in the watershedof the Seto Inland Sea （2006）
Name of Pref.
Total in Japan (A)Kyoto Pref.
Osaka Pref.
Hyogo Pref.
Nara Pref.
Wakayama Pref.
Okayama Pref.
Hiroshima Pref.
Yamaguchi Pref.
Tokushima Pref.
Kagawa Pref.
Ehime Pref.
Fukuoka Pref.
Oita Pref.
Total in the 13 Pref. (B)(B)/(A)％

Population(thousand)Seto Inland
Total
Sea Area―
127,055

Land Area(km2)
Seto Inland
Total
Sea Area―
377,915

Population Density(persons/km2)
Seto Inland
Total
Sea Area
―
336

2,642
8,822
5,594
1,414
1,060
1,954
2,876
1,480
803
1,009
1,480
5,030
1,205
35,369
27.8％

4,613
1,896
8,396
3,691
4,726
7,113
8,477
6,112
4,145
1,876
5,677
4,976
6,339
68,037
18.0％

572
4,651
667
383
224
275
339
242
193
538
261
1,011
190
520
―

2,306
8,822
5,440
1,363
778
1,954
2,728
1,368
779
1,009
1,440
1,112
1,103
30,202
―

1,773
1,896
6,665
1,790
1,687
7,113
5,848
5,564
3,651
1,876
4,753
1,068
4,796
48,480
―

1,300
4,651
817
761
461
275
466
246
213
538
303
1,041
230
623
―

Note: Source; Ministry of Internal Affairs and Communications of Japan

The population of the area is about 35 million, that is, about 18 % of the total populationof Japan, and its annual specific increasing rate is around 2.8 % which is similar to the average
for all over Japan as shown in Figure 1-3.
Further, as shown in Figure 1-4, the population density is 643 persons/km2, which is
1.6 times larger than the average of Japan, which is about 340 persons/km2. This means the
population is highly concentrated in this area.

Population (Thousamd)

140,000
Japan
Total of 13 pref. concerned

120,000
100,000
80,00060,00040,00020,000
0
1955

1960

1965

1970

1975

1980

1985

1990

1995

2000
Year

Note: Source; Census for fiscal year of 2005

Figure 1-3 Population all over Japan and the prefectures located in thewatershed of the Seto Inland Sea− 6 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

4,656
4,651
4,651
1,300
572

Hyogo Pref.
817

Kyoto
Pref.

667

Osaka
Pref.

Okayama Pref.

761

275 275

大Hiroshima Pref.
466

Nara
Pref.

339

538 538
246 242

Yamaguchi
Pref.

KagawaPref.
Tokushima Pref.

Ehime Pref.

1,041 1,011

Fukuoka
Pref.

阪 383

213 193

461
224

Wakayama
Pref.

303 261

230 190

LegendOita Pref.

Seto Inland Sea area（man/km2）
Total in each Pref.（man/km2）

0

10

20

Boundary among Pref.

30 km

Note: Source; The Association for the Environmental Conservation of the Seto Inland Sea

Figure 1- 4 Population density of each prefecture in the watershed area of the Seto Inland Sea− 7 −Chapter1 OUTLINE OF THE SETO INLAND SEA
1.4 THE ENVIRONMENT(1) Characteristics of the environment in the Seto Inland Sea
The Seto Inland Sea is typical of the outstanding beautiful scenery that can be seenin Japan, and there are many national parks, quasi-national parks, and other parks in this area
as shown in Figure 1-5. The Seto Inland Sea National Park was designated as one of the firstnational parks in Japan. Many people have evaluated the area as having "peaceful and beautiful
scenery with diversity", which makes it stand apart from other national parks, that arecharacterized by grand and unaffected scenery.

Kyoto Pref.
Hyogo Pref.
Okayama Pref.

Special Sanctuary(Ikishima)

Osaka Pref.

Hiroshima Pref.

Nara Pref.

Seto-naikai National Park

Kagawa Pref.

Yamaguchi Pref.

Wakayama Pref.

Tokushima Pref.
Ehime Pref.

Muroto-Anan
Quashi-national Park

FukuokaPref.
LegendOita Pref.
Nippou-Kaigan
Quashi-national Park

Designated Land Areain Seto-naikai National Park
Designated Sea Areain Seto-naikai National Park

Ashizuri-Uwakai
National ParkThe other Parks in the Seto Inland Sea
0

10

20

30 km

Note: Source; The Association for the Environmental Conservation of the Seto Inland Sea

Figure 1-5 National Parks in the Seto Inland Sea
Areas of vegetation around the Seto Inland Sea were originally mostly occupied bywarm temperate laurilignosa. The tree layer was dominated by chinquapin, oak, camphor trees,
macilus tunbergii. The bush layer was dominated by vegetation that can tolerate shade, suchas holly, camellia etc.
Because civilization has developed since ancient times along the coastal areas aroundthe Seto Inland Sea, the original vegetation can remain only in parts of grounds and gardens
in shrines and/or temples and places of scenic beauty and historical importance. Almost all
species of the present vegetation have been affected artificially and are characterized by secondary
forests of Japanese red pine and Japanese black pine among granite soil. Forests of holm-oak,which we can easily find in this area, offer a wonderful and unique scene.
(2) The Seto Inland Sea National ParkThe Seto Inland sea, which is punctuated by three straits (the Kitan, Naruto, Kanmonand Hoyo Straits) is 2,200,000 ha in area, of which 62,000 ha is designated as a national park.
The Seto Inland Sea National Park is summarized in Table 1-5. Its history as a national park,
the land area of each classified level of the park, and the land area of each classified owner
thereof are shown in Table 1-6, 1-7 and 1-8, respectively.

− 8 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Table 1-5 Outline of the Seto Inland Sea National Park
Characteristics of Scenery

Park Name

Total

PlantsGeographical features

The Seto Inland Sea Worldwide sea
park with a
Date of registration: large number
March 16, 1934
of islands
Area : 66,934 ha
History andtraditions

Sea bream、monkey

Misen primeval forest(natural treasure)Inland sea with alarge number ofislands

Stopovers for
Red-throated Diver(natural treasure)

Camphor tree community
in Oyamazumi Shrine

Large eddy &tidal current(Naruto &KurushimaStraits)

Lignosa in Ikishima Island(natural treasure)
Lignosa in Mt. Gabisan(natural treasure)

Old volcanic lava
plateau & eroded
geographicalgranite mountains

Pref.
concerned

Animals

Propagation area for
Horseshoe crab
(natural treasure)

Hyogo
Wakayama
Okayama
Hiroshima
Yamaguchi
Tokushima
KagawaEhime
FukuokaOita

Sea surface withswimming area ofFinless Porpoise(natural treasure)

Juniperus chinensis in
Hosan-in(Special natural treasure)

Habitat of amphioxus(natural treasure)

Grove in Miko Shrine(natural treasure)Note: Source; Association of National Park 2005

Table 1-6 History of designation as a national park
Date
March 16, 1934
May 18, 1950
May 1, 1956
March 9, 1963
August 23, 1968
April 12, 1971
February 17, 1982

OutlineDesignation as a national park
Second expansion (Naruto, Miyajima and other areas)
Third expansion (Rokko and other areas)
and incorporation of the Takasakiyama region in Aso National Park
Addition of the Kata region
Addition of the Goshikidai region
Exclusion of part of the Rokko area
Exclusion of some regions in Okayama Pref., Tokushima Pref. and others

Note: Source; Association of National Park

Table 1-7 Land area of the each classified level of the park (Unit: ha, March 31 in 2005)
Specified Region
Total Area Strict Protected
First Class
Zone
66,934953 (1.4 %)4,700

Second
Class

Third
Class

Total of First
to Third class

General Region

31,034

7,519

43,25 (64. 6 %)22,728 (34.0 %)Note: Source; Association of National Park

Table 1-8 Land area of each classified owner (Unit: ha, March 31 in 2005)
Total Area

Government owned

PublicPrivate66,934

7,897 (11.8 %)10,718 (16.0%)

48,319 (72.2%)

Note: Source; Association of National Park

The most important characteristic of the Seto Inland Sea is its beautiful sea zone withits many small islands; therefore, this national park comprises Ie-shima Islands, Bisan Islands,
Geiyo Islands, Boyo Islands and other islands. Furthermore, this park includes scenic spots forthe islands such as the Rokko Mountain areas that are located in the north of Kobe City.
Another important characteristic of the Seto Inland Sea is its human activities, whichmakes this scenery seem very familiar. The distinctive feature of this park is the symbiotic
relationship between humans and nature, such as terraced fields, houses in old port towns, thebusy movement of cruisers and ships. The number of tourists visiting the park is second only
to the Fuji-Hakone-Izu National Parks as shown in Table 1-9.

− 9 −Chapter1 OUTLINE OF THE SETO INLAND SEA
Table 1-9 Number of tourists visiting national parks (2004)
Rankingin 1995

Number of Tourists Ratio to Total Number Ranking(thousands)of Tourists (％)
in 1995

Park Name

1

Fuji-Hakone-Izu

102,041

29.0

1

2

Seto Inland Sea

38,191

10.9

2

3

Jyoushinetsu Kougen Highland

28,9938.3

3

4

Aso-Kuju Mts.

22,894

6.5

5

5

Nikkou19,4365.5

4

6Chichibu-Tama

14,820

4.2

7

7

Kirishima-Yaku

12,1543.5

9

8

Shikotsu-Toya

11,5463.3

6

9

Ise-Shima

10,173

2.9

10
―

10

Chubu-Sangaku

10,123

2.9

Total of Top 10 National Parks

270,371

75.8

Total of 28 National Parks

351,350100.0

Note: Source; Association of National Park

(3) Sea-grass Bed and Tidal Flat
The sea-grass beds and the tidal flats in the Seto Inland Sea area have decreased.
The former is considered to be important as a zone for nursery grounds of shells and fish.
The latter plays an important role in the ecosystem and in self-purification. The area of the
sea-grass bed and the tidal flats in the Seto Inland Sea is shown in Table 1-10, and trends foreach total area are shown in Figure 1-6 and 1-7.
Area (ha)30,00022,63520,000

Seagrass Bed
Seaweed Bed

10,623

10,0005,574 4,529

0

1960

1966

7,011

1971

5,729

1978

6,381 5,511

1989〜90 Year

Note: Source; The Association for the Environmental Conservation of the Seto Inland Sea

Figure 1-6 Trends in areas of sea-grass bed in the Seto Inland Sea

Area (ha)30,00025,19020,49020,00015,20015,00012,548

11,734

Tidal Flat

10,000
0

1898

1925

1949

1969

1978 1989〜90 Year

Note: Source; The Association for the Environmental Conservation of the Seto Inland Sea

Figure 1-7 Trends in areas of tidal flats in the Seto Inland Sea− 10 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Table 1-10 Areas of the sea-weed bed and tidal flat in the Seto Inland Sea

Northern
Osaka BaySouthern
Osaka Bay
Northern
Harima-nadaSouthern
Harima-nada
Eastern Kii
ChannelWestern Kii
ChannelHiuchi-nada
Eastern
Bisan Strait
Western
Bisan Strait
Bingo-nada
Aki-nada
Hiroshima
Bay
Eastern
Iyo-nada
Western
Iyo-nada
Beppu Bay
Eastern
Suo-nada
Western
Suo-nada
Bungo
Channel
Total

Area of Each Type of Existing Sea-weed Bed (ha)Kelp Arame Garamo Wakame Tengusa Amamo Aosa andSeaweed Seaweed Seaweed
Green Others
Zone
Zone
Zone Laver Zone
Zone
Zone
Zone
59
0
0
0
0
0
3
0
(42)
26
208
12
197
198
0
98
89
(1)
(1)
(2)
(118)
(25)
142
71
0
176
132
13
0
0
(4)
(4)
(4)
(218)
(98)
(49)
189
225
0
37
207
28
28
35
(14)
(8)
476
304
0
11
177
46
19
96
(2)
(13)
452
77
180
42
19
0
5
32
(1)
(6)
(7)
(52)
(12)
383
1,111
108
103
0
149
1
0
(5)
(9)
(2)
(4)
8
241
88
452
8
389
0
0
(30)
(11)
(209)
(1)
188
45
974
0
0
44
228
0
(16)
(6)
(57)
510
85
0
0
157
0
2
426
(18)
(11)
229
999
86
620
0
71
6
1,738
(4)
(2)
(1)
(2)
124
204
101
0
35
0
31
128
(6)
(6)
(4)
426
264
474
168
119
0
10
48
(1)
(33)
(33)
(16)
(1)
0
0
0
0
0
0

733

85

81
(82)
567
(3)

125
(82)
797
(6)

8

24

1,398
(4)
4,617
(98)

1,314
(1)
5,511
(218)

0

209

21

60

35

10

51

97

477
(1)

85
(60)
362
(11)

85

60

372
(19)
2,292
(17)

180
(11)
940
(13)

13

14

1

0

34

7

75

122

896
(64)

1,250
(5)

6,381
(630)

4,667
(346)

3,102
(118)

Total
(ha)
62
(42)
828
(147)
534
(377)
749
(22)
1,129
(15)
807
(78)
1,855
(20)
1,186
(251)
1,479
(79)
1,180
(29)
3,749
(9)
623
(16)
1,509
(84)
1,143
(0)
497
(224)
2,852
(51)
3,292
(30)
2,950
(5)
26,424(1479)

Area of
Existing
Tidal Flat

(ha)
2
(0)
13
(0)
135
(55)
22
(0)
57
(0)
120
(70)
1,022
(52)
400
(4)
496
(69)
782
(124)
221
(4)
394
(15)
49
(0)
135
(3)
421
(281)
824
(30)
6,409
(85)
232
(22)
11,734(814)

Note : 1) Figures in parenthesis show the reduced area after the second survey in 1978
2) Area is double-counted if multiple types exist in the same sea-weed bed3) Source; Environment Agency in 1994 (the 4th survey)

Table 1-10 shows that the Zostera zone is 6,381ha, which is the largest area in the
Seto Inland Sea, while the Garamo (Sargasso) zone is 5,511ha and the Ulva and Enteromorphazone is 4,667ha. As for the area of the tidal flats, the largest one with 6,409ha is located in thewestern part of Suo-Nada and the second largest one with 1,022 ha is in Hiuchi-Nada.
Since ancient times, the coastline of the Seto Inland Sea has been changed by reclamation
for agriculture and salt farmland because of its shallow depth. The rapid industrialization fromthe 1960s required a great deal of reclamation and, as a result, the natural coastline is only 37% of the total coastline of the Seto Inland Sea at present, which is less than the value forJapan as a whole (55.2 %). Artificial beaches have been created to restore lost natural beaches.
The state of the coastline of the Seto Inland Sea is shown in Table 1-11 and Figure 1-8, andthe state of protected water areas are shown in Figure 1-9.

− 11 −

Chapter1 OUTLINE OF THE SETO INLAND SEA
Table 1-11 The state of the shore line along the Seto Inland Sea
Natural Seashore Semi-natural Seashore Artificial Seashore Mouth of River
Pref.
Osaka

Hyogo

Wakayama

Okayama

Hiroshima

Yamaguchi

Tokushima

KagawaEhime

Fukuoka

Oita

Seto Inland Sea

All Japan

Year

Length
Km

1996
1993
1984
1978
1996
1993
1984
1978
1996
1993
1984
1978
1996
1993
1984
1978
1996
1993
1984
1978
1996
1993
1984
1978
1996
1993
1984
1978
1996
1993
1984
1978
1996
1993
1984
1978
1996
1993
1984
1978
1996
1993
1984
1978
1996
1993
1984
1978
1996
1993
1984
1978

1.9
2.3
2.8
3.6
144.0
144.0
144.5
146.6
100.7
97.4
97.4
82.8
250.8
237.5
238.9
243.1
349.0
355.3
366.0
369.6
503.0
493.4
501.8
497.7
80.7
79.5
79.6
81.7
322.1
337.4
345.8
350.3
680.3
569.8
579.6
688.6
40.8
40.3
39.9
42.2
170.9
181.2
183.5
191.1
2,654.2
2,538.1
2,579.8
2,697.3
17,660.3
18,105.6
18,402.1
18,967.2％

Length
Km

0.8
1.1
1.4
1.9
22.0
22.0
22.7
23.8
45.7
45.6
47.9
46.3
45.7
47.2
47.9
48.9
31.5
33.0
34.3
35.0
45.1
45.7
47.1
47.7
33.2
35.8
35.8
37.5
46.8
48.0
49.7
50.8
44.5
41.9
42.8
48.2
14.5
14.8
15.8
17.4
29.8
31.9
33.1
35.2
36.7
27.0
38.2
40.2
52.6
55.2
56.7
59.0

10.9
10.9
11.7
11.9
123.8
123.8
124.6
129.1
30.9
42.7
43.6
44.3
80.5
71.9
77.9
79.6
59.3
49.4
57.5
59.0
60.0
59.7
59.3
55.9
21.7
22.2
22.3
22.9
118.7
126.3
138.0
138.0
348.9
350.1
363.5
359.0
17.6
18.5
20.8
20.2
83.7
80.9
81.5
81.7
956.0
956.4
1,000.7
1,001.6
4,385.1
4,467.5
4,511.4
4,340.0％

Length
Km

％

4.5
5.0
5.6
63.
18.9
18.9
19.5
21.0
14.0
20.0
21.5
24.9
14.7
14.3
15.6
16.0
5.3
4.6
5.4
5.5
5.4
5.5
5.6
5.4
8.9
10.0
10.0
10.5
16.7
18.0
19.8
20.0
22.8
25.7
26.8
25.1
6.2
6.8
8.2
8.4
14.6
14.2
14.7
15.0
13.2
13.9
14.8
15.0
13.1
13.6
13.9
13.5

224.9
197.0
187.3
166.4
382.9
382.9
363.7
334.8
85.5
70.8
59.7
48.7
207.4
186.0
174.8
167.2
692.9
663.7
637.0
621.0
539.4
516.5
494.1
481.5
133.8
114.2
114.2
107.5
250.6
233.9
206.1
194.8
486.3
420.8
393.7
363.4
220.6
212.4
191.5
178.7
309.2
297.0
279.8
260.6
3,533.0
3,295.2
3,101.9
2,924.6
11,212.2
9,941.8
9,294.5
8,598.9

92.6
91.2
90.2
88.6
58.4
58.4
57.0
54.4
38.3
33.2
29.4
27.3
37.8
37.0
35.0
33.6
62.5
61.7
59.7
58.8
48.3
47.9
46.4
46.1
55.0
51.5
51.5
49.3
35.3
33.2
29.6
28.3
31.8
31.0
29.0
25.4
78.1
78.0
75.6
73.7
53.9
52.3
50.5
47.9
48.9
48.0
45.9
43.6
33.4
30.4
28.6
26.7

Length
Km
5.2
5.9
5.9
5.9
5.1
5.1
5.1
5.1
3.3
2.6
2.6
2.7
10.3
7.4
7.4
7.3
8.3
6.9
6.9
6.9
13.3
9.3
9.3
9.3
7.0
5.9
5.9
5.9
8.0
5.8
6.0
6.1
11.9
18.9
18.9
18.9
3.4
1.1
1.1
1.1
10.1
9.3
9.3
10.1
85.9
78.2
78.4
79.3
316.2
264.0
263.8
263.7

％

Total
Length
Km

2.1
242.9
2.7
216.1
2.8
207.7
3.2
187.8
0.7
655.8
0.7
655.8
0.8
637.9
0.8
615.6
1.5
220.4
1.2
213.5
1.3
203.4
1.5
178.5
1.9
549.0
1.5
502.8
1.5
499.0
1.5
497.2
0.8 1,109.4
0.7 1,075.3
0.6 1,067.3
0.7 1,056.5
1.2 1,157.7
0.9 1,078.9
0.9 1,064.4
0.8 1,044.4
2.9
243.2
2.7
221.8
2.7
222.0
2.7
218.0
1.1
709.4
0.8
703.4
0.9
695.8
0.9
689.2
0.8 1,527.4
1.4 1,359.6
1.4 1,355.7
1.3 1,429.9
1.2
282.4
0.4
272.3
0.4
253.3
0.5
242.2
1.8
573.9
1.6
568.4
1.7
554.0
1.9
543.5
1.2 7,229.5
1.1 6,867.9
1.2 6,760.8
1.2 6,702.8
0.9 33,573.8
0.8 32,778.9
0.8 32,471.9
0.8 32,170.2

Note: 1) Source; Environment Agency of Japan (second survey 1978, third survey 1984, fourth survey 1993 andfifth survey 1996)
2) Regions of the Seto Inland Sea are based on the Law Concerning Special Measures For Conservation of
The Environment of The Seto Inland Sea− 12 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Kyoto Pref.

Hyogo Pref. 1

Okayama Pref.
2

2
1

22
4
58

45

38

1

19
93

15
31

Osaka Pref.

63

Yamaguchi
Pref.

5
1

1

1

45

49

Nara
Pref.

Hiroshima Pref.
Kagawa
Pref.

39

46

3
5

35

14
47
33

17

55

1

1

Wakayama
Pref.

9

Fukuoka Pref.

Tokushima Pref.

32

44

14
6

23

79

Ehime Pref.
Oita Pref.

Legend2

Natural Seashore
Semi-natural
Seashore
Artificial Seashore

30
53
15

Estuary
0

10

Note:

20

Estuary

NaturalSeashore

Artificial
Seashore

Semi-natural
Seashore

30 km1) Source; Environment Agency of Japan (fourth survey 1993)
2) Regions of the Seto Inland Sea are based on the Law Concerning Special Measures For Conservationof The Environment of The Seto Inland Sea

Figure 1-8 The state of the shore line along the Seto Inland Sea
Seaweed Bed

Shell Fish

32

22

No. of Sea All over Japan
Regions Seto Inland Sea
Area
(ha)

24

3

All over Japan 1,577.5 ha

1,370.5 ha

Seto Inland Sea 1,301.0 ha

82.3 haKyoto Pref.
Hyogo Pref.
Okayama Pref.
Tamano-city Handen Zisaki(1982)

Hiroshima Pref.
Iwakuni-city Katurasima
Zisaki(1974)
Kurahashi-cho Zisaki(1971)
Tono-cho Zisaki(1973)

Kasaoka-city
takasima Zisaki(1979)

Ushimado-cho Zisaki(1983)

Sakaide-city
Tamagoe-cho Zisaki(1974)
Takuma-cho Zisaki(1969)

Yamaguchi Pref.

Kagawa Pref.

Toyoura-cho Kouzima Zisaki(1976)
Akiho-cho Takeshima
Zisaki(1998)

Kannonji-city
Ibuki-cho Zisaki(1987)
Nakajima-cho Futakamijima
Zisaki(1973)

Tokushima Pref.

Osaka
Pref.
Nara
Pref.

Gosiki-cho Zisaki(1984)
Seidan-cho Zisaki(1967)
Nandan-cho Zisaki(1972)

Wakayama
Pref.

Higashikunisaki-gun
Himesima-muraKaminoseki-cho Yashima Zisaki(1969)
Zisaki(1977)
Higashikunisaki-gun
Kunimi-cho Zisaki(1975) Ehime Pref.

FukuokaPref.

Usa-city Yokkaichi
Aki-cho, Musashi-cho
Zisaki(1966)
Zisaki(1981)
Usa-city Yanagiura Hiji-machi Zisaki(1998)
Zisaki(1966)
Saganoseki-machi Zisaki(1974)
Usa-city Kazuma
Zisaki(1954)
Tsukumi-city Hotojima Zisaki(1976)
Tsukumi-city Sensui Zisaki(1979)
Kamiura-cho Zisaki(1972)

Legend● Seaweed Bed◯ Shell Fish

Oita Pref.
0

10

Note:

20

30 km

1) Summation of the state on March 1 1998
2) Figures in parenthesis show the fiscal year of designation
3) "Protected water surface" means a water zone which is designated on the basis of the Law for Conservationof Fisheries Resources as a zone to be protected with respect to the spawning of fish and shell fish, growthof the fry, and/or production of fish and shell fish4) Source; Fisheries Agency of Japan

Figure 1-9 The state of protected water areas in the Seto Inland Sea− 13 −

Chapter1 OUTLINE OF THE SETO INLAND SEA(4) Flora and Fauna (Plants and Animals) in the Seto Inland Sea
Pine forests are especially important as a component of natural scenery in the Seto
Inland Sea. But recently, these pine forests have been damaged by pine-worm. The area ofsuch damage increased year by year from 80,000 m3 in 1970, to about 840,000 m3 in 1980, reachinga peak in 1979. It has been gradually decreasing to 330,000 m3 as of 1996. Protected areas forbirds and animals were designated at 819 sites (total area of 519,000ha) by April 1998, of which
135 sites (total area of 22,000 ha) were designated as strictly protected zones. The location ofeach strictly protected zone for birds and animals in the Seto Inland Sea is shown in Figure
1-10.

Kyoto Pref.
Hyogo Pref.
Okayama Pref. Ako Sakoshi Area

(preffecturally-designated)

Osaka
Pref.

Hamakoshien Area
(government-designated)

Hiroshima Pref.

Tsunoshima Area
(preffecturally-designated)

Ohamasaki Area
(preffecturally-designated)

Kabeshima Area
(preffecturally-designated)

Kagawa Pref.

Nara Pref.
Tomogashima Area
(government-designated)

Yamaguchi Pref.

Itsukishima Area
Omiko Area
Mukoshima Area (preffecturally-designated) (preffecturally-designated)(preffecturally-designated)
Tokushima Pref.
Gabisan Area (preffecturally-designated)
Shirashima Area
Wakayama Pref.
(preffecturally-designated)
Ishima Area
Ehime Pref.
Ushima Area
(preffecturally-designated)(preffecturally-designated)FukuokaPref.

Takashima Area
(preffecturally-designated)

Oita Pref.
Tsurumisaki Area
(preffecturally-designated)
0

10

20

Kashima Area
(preffecturally-designated)

LegendBoundary among Prefectures

30 km

Area of the Seto Inland Sea

Note: Zones which include shore line in the Seto Inland Sea are illustrated

Figure 1-10 The strictly protected zone for birds and animals in the Seto Inland Sea

As for bird-watching facilities in the nature there are 13 sites designated as wild-birdforests in Takamatsu City in Kagawa Prefecture, in Ishii Town in Tokushima Prefecture, inUwajima City in Ehime Prefecture and so on.

− 14 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA(5) Culture in the Seto Inland Sea
There are a lot of cultural assets consisting of famous historic sites and structures, as
the area around the Seto Inland Sea has been developing from ancient times. Many of themdisplay excellent natural scenery in harmony with local circumstances, and designated ashistorical relics, place of beauty and natural monuments as well as the other special aspects ofnature. Location of the main cultural assets in the coastal zone of the Seto Inland Sea is shownin Figure 1-11.

Hyogo Pref.
Okayama Pref. Garden of Ako castle
Enkyoji temple
Himeji castle(Tokushi)

Hiroshima Pref.

Kyoto
Pref.

Goshikizuka tumulus
Tombs of Kusunoki Masashige
Otomezuka tumulus
Nishinomiya battery

Tabuchi's garden
Ako castle
Propagtion area ofIkishima
Horse shoe crab
Onaka ruins
Saregent juniper at Hojoin
Sakai lighthouse
Wadamisaki
Kiheijima saltwork(Tokuten)
Yotsuike ruins
battery
ruins
Cycad of Seiganji
Nansouji garden
Bush at Tadamihachiman
Ojinyama
Shimotui-Washuzan
Toms of Nakayama Tadamitsu
Kankakei
Nojima fault
Fukuyama castle
Ikegami-Sone ruins
Camphor tree of Oyamazumi shrine
Ayaragigo ruins
Quarry ruins
Shiraisijima
Hiroshima castle
Kajikurihama ruins
Bush at Miko shrine
Jodoji garden
Hinesou ruins
Sumoto castle
Elephant-shaped rock
Nagato casting ruins
Atomic bomb dome
Takasima
Syukukei
Takamatsu
castleToms of Takasugi Shinsaku
Sairyou
tumulus No.1 No.2
Burial mounds of Nakaoda
gardenTomo park
YashimaKieinomatsubara
Burial mounds of Iwahashi Sentsuka
Misen primeval forest
Shiwaku official Ritsurin park
Kabejima(Cormorant habitat)
Wakayama castle(Tokushi)
Naruto Narukami
Habitat of Finlesshouse ruins Marugame castle
ItsukushimaDi¥oigahama ruins
Yosuien
Porpoise(Sunameri)
Armor-shaped rock in Shiraisijima
shell mounds(Tokushi, Tokumei)
Kurusonyama
Omishima
Kogusi(colony of ehime iris)
Noshima castle
Stopovers of Red-throated Diver(Abi)Pine tree in Naruto
Tombs of Tokugawa's family
Ogoyakoumorido Suonada reclaimed ruins
Hachimanyama
Kotohiki park
Stupa in the ruins of Myoekishu
Lamprophyre vein of Shikauragoe
Kintaikyo
Hatohama
Hagiokan
Senju Iignosa
Bank of Hiromura
Spherical Norite in Marukamijima
Kinujima and Marugamejima
Mukojima(Raccooc dog habitat)
Iyo-kokubunji
Tombs of Hamaguchi Satoru
Suokokuga ruins
Chausuyama tumulus Shishimagahara
Big rock of Monzen
IwakisanSorinji garden
Houanji
Manju IignosaAnkasyo(chinees pear)
Jinmayama tumulus Gabisan Iignosa
Colony of tropical plants at Bentenjima
Matsuyama castle
Yoda-garyubai
Mica-basait of Mutsurejima
Gosyoga
Ishizukayama tumulus
dani
Kobayakawa castle
Habitat of Cephalochordata(Namekujiuo)

Yamaguchi Pref.

Osaka Pref.

Nara
Pref.

Kagawa Pref.

Tokushima Pref.

Wakayama
Pref.

Gosyoyama tumulus
Hukuzawa Yukichi house

Onituka tumulus
Ankokuji town ruins

Hokyouji

Usa shrine
Fukuoka
Kumano magaibutsu
Pref.
Cycad of Matsuoji

Ehime Pref.
LegendMisaki(Ako tree)

Camphor tree of Yusuhara shrine
Otomo's house
Tsukiyama tumulus
Bungo-kokubunji
Shimoyama tumulus
Usuki magaibutsu
Kariu cavem

Historical monument

Oninoiwaya tumulus

Takasakiyama(Monkey habitat)

Uwajima castle
Tensyaen

Beatiful place
Natural monument(Tokuten)：Special historical monument

Root tree of mandarine of Ozaki(Tokushi)：Special beatiful place

Oita Pref.
0

10

Note:

20

(Tokumei)：Special natural monument

30 km1) Zones designated by the Law for Protection of Cultural Assets
2) Source; Catalogue of designated monuments

Figure 1-11 Location of the main cultural assets in the coastal zone of the Seto Inland Sea− 15 −

Chapter1 OUTLINE OF THE SETO INLAND SEA
1.5 FISH PRODUCTION
Fish production is defined as the fish catch per unit time and unit area, and fish
production in representative semi-enclosed coastal seas all over the world, given in Figure 1-12,
is shown in Figure 1-13. Fish production of 20.6 ton/km2/year in the Seto Inland Sea, Japan is
the largest among these coastal seas. Fish production in Chesapeake Bay, U.S.A., is 6.5 ton/km2/year; in the North Sea 5.7 ton/km2/year; in the Baltic Sea 2.2 ton/km2/year; in the Black Sea
1.4 ton/km2/year; and in the Mediterranean Sea 0.8 ton/km2/year.

4

3
6

2

5

1

Figure 1-12 Representative semi-enclosed coastal seas throughout the world①: Seto Inland Sea ②: Chesapeake Bay ③: Baltic Sea ④: North Sea⑤: Mediterranean Sea ⑥: Black Sea

ton / km2 / year
25
20
15
10
5

Black Sea

Mediterranean
Sea

North Sea

Baltic Sea

ChesapeakeBay

Seto InlandSea

0

Figure 1-13 Fish production in representative semi-enclosed
coastal seas throughout the world− 16 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

For fish-growing, it is necessary to utilize phytoplankton, which assimilates
nutrients such as nitrogen and phosphorus through photosynthesis. The nutrients in the coastal
sea are mainly supplied from the land. The difference in fish production shown in Figure 1-13
is the result of the difference between transport mechanisms for water and nutrients in thesemi-enclosed coastal seas shown in Figure 1-12. The transport mechanisms of nutrients loaded
from the land in those semi-enclosed coastal seas are shown schematically in Figure 1-14.

Seto Inland Sea

nutrients

Chesapeake Bay

straitstraitnutrients

North Sea
nutrients

Baltic Sea, Black Sea

nutrients

Mediterranean Sea

nutrients

evaporation

Figure 1-14 Transport mechanisms for water and nutrients in the representative
semi-enclosed coastal seas throughout the world

In the Mediterranean Sea (maximum depth 5,000 m), the surface water becomes heavy
due to large evaporation, sinks to the deep aphotic layer and flows out to the Atlantic Ocean
through the lower layer of the Straits of Gibraltar (maximum depth 200 m). The origotrophic
surface water of the Atlantic Ocean flows into the euphotic layer of the Mediterranean Sea
through the upper layer of the Straits of Gibraltar. Therefore the nutrients loaded from theland flows out through the lower layer of the Straits of Gibraltar without being assimilated byphytoplankton in the Mediterranean Sea and, as a result, its fisheries production is very small.
In the Baltic Sea (maximum depth 500 m) and the Black Sea (maximum depth 2,000 m),
where the summation of precipitation and fresh-water discharge is larger than the evaporation,
the surface water is light and flows out through the upper layers of the Kattegat (maximum
depth 20 m) to the Atlantic Ocean and through the Bosporus (maximum depth 50 m) to theMediterranean Sea, respectively. The nutrients loaded from the land also flow out, being
assimilated by phytoplankton in the euphotic layer. The waters of the Atlantic Ocean and theMediterranean Sea flow into the Baltic Sea and the Black Sea through the lower layers of the
Kattegat and the Bosporus, respectively. The bottom waters in the Baltic Sea and the BlackSea have no sunlight due to its depth, the organic matter that sinks from the upper layer isdecomposed by bacteria using the dissolved oxygen and an oxygen-deficient water mass
(hypoxia or anoxia) is generated there.
The winter convection cannot reach the bottom
because the difference in density between the surface and bottom layers in the Baltic and− 17 −

Chapter1 OUTLINE OF THE SETO INLAND SEA
Black Seas is large and the oxygen-deficient water mass does not disappear throughout theyear. The marine biota cannot live in the bottom layers of the Baltic and Black Seas due tothe existing oxygen-deficient water mass. Such a situation results in small fish production there.
In the anoxic water mass, which is an extreme case of oxygen-deficient water mass, where
the dissolved oxygen concentration is zero, sulfide reduction begins by using sulfate ion in theseawater. The very name Black Sea originated from the accumulated black hydrogen sulfide
generated by sulfate ion at the sea bottom there.
In the North Sea (average depth 90 m), where a counterclockwise circulation dominates
throughout the year, the nutrients from the subsurface layer of the Atlantic Ocean flow in a
repeated process and are assimilated by phytoplankton in the euphotic layer and then decomposedby bacteria in the aphotic layer, finally flowing out to the Arctic Ocean from the offshore area
west of Norway. Therefore fish production in the North Sea is larger than in the MediterraneanSea, the Black Sea and the Baltic Sea but smaller than in Chesapeake Bay and the Seto InlandSea, as will be discussed next.
In Chesapeake Bay (average depth 6 m; deepest part 50 m) with its large freshwater
discharge, an estuarine circulation dominates with seaward flow in the upper layer and landward
flow in the lower layer. Nutrients loaded at the bay head flow seaward and are assimilated byphytoplankton in the euphotic upper layer, fecal pellets and dead phytoplankton sink to theaphotic lower layer, and the sunken fecal pellets and dead phytoplankton flow landward while
being decomposed by bacteria in the aphotic lower layer. The nutrients generated fromdecomposed organic matter upwell to the euphotic upper layer, are assimilated again byphytoplankton and flow out to the Atlantic Ocean. The nutrients in Chesapeake Bay are
assimilated many times by phytoplankton through the above process. Such a transport mechanism
for nutrients is called a trapping mechanism for nutrients in the estuary (Figure 1-15). Thus, fish
production in Chesapeake Bay is larger than in the Mediterranean, Black, Baltic and North Seas.

Loads of
Water
And
Nutrients

Estuarine
circulation

Phyto and
Zoo
PlanktonFecalpelletnutrients

Figure 1-15 Water and nutrient transports in the estuary

In the Seto Inland Sea (average depth 20 m; deepest part 300 m) with many straits,in addition to the trapping mechanism of nutrients seen in the estuary of Chesapeake Bay,
nutrients are mixed horizontally and vertically in the straits and the average residence timeof nutrients in the Seto Inland Sea is longer than in Chesapeake Bay. This means that the time
the nutrients are assimilated by phytoplankton is greater in the Seto Inland Sea than in
Chesapeake Bay. As a result, fish production in the Seto Inland Sea is greatest, as shown in
Figure 1-13.

− 18 −

Chapter 2 CHANGES IN THE ENVIRONMENT OF THE
SETO INLAND SEA
2.1

INDUSTRIAL AND HUMAN ACTIVITIES

20

2.2 NEGATIVE LOAD ON THE ENVIRONMENT

27

2.3 CHANGES IN WATER AND SEDIMENT QUALITY

33

2.4 OCCURRENCE OF RED TIDES

45

2.5 MARINE POLLUTION FROM OIL SPILLS AND

55

OTHER CAUSES− 19 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
2.1 INDUSTRIAL AND HUMAN ACTIVITIES
2.1.1 Gross Product in the 13 Prefectures around the Seto Inland Sea
Trends relating to the gross prefectural product of the 13 prefectures around the Seto
Inland Sea from 1965 to 2003 are shown in Figure 2-1.
The gross product of the 13 prefectures was 129.8 trillion yen in 2002. The grossproduct from 1965 to 1995 had increased steadily, with an annual rate of increase of about 0.53 %.
However, since 1996 the increase is not very distinct and the production level has become rather
constant.
With respect to the composition of industry in 1965, the primary industries accounted
for 7.4 %, the secondary industries represented 40.0 %, and the tertiary industries 52.6 % . From1965 to 1995, the ratio of secondary industries decreased by 7.3 %, while tertiary industries
increased by 13.6 %,, and this trend has not changed very much since then. The ratio in 2002,
for example, was 0.85 % for primary, 25.3 % for secondary, and 73.8 % for tertiary industries.

Tertiary Industry
Secondary Industry
Primary Industry

Gross Prefectural Production( 10 billion Yen )160,000
140,000
120,000
100,000
80,00060,00040,00020,00001965 1970 1975 1980 1985 1990 1995 1996 1997 1998 1999 2000 2001 2002 2003 Year

Note: survey conducted by the Association for the Environmental Conservation of the Seto Inland Sea

Figure 2-1 Trends in and ratio of gross prefectural product in the 13 prefectures aroundthe Seto Inland Sea

2.1.2 Industrial Shipping in 13 Prefectures around the Seto Inland Sea
The Seto Inland Sea offers advantageous conditions for industrial development, suchas long shallow coasts suitable for factory construction, and a population of some thirty million
people living along the coastal areas.
In the period of rapid economic growth of the 1950s and 1960s, heavy and chemical
manufacturing industries grew up around the Seto Inland Sea, responding to the national
government's policy of doubling income scheme. At present the production capacity of manufacturingindustries in the area occupies more than 30 % of the total for Japan.
There are basic manufacturing industries such as steel, oil refinery, and petrochemicalindustries in 13 prefectures around the Seto Inland Sea, trends in total shipping are shown in
Figure 2-2. The volume of shipping in this area has increased up to 1990, but since then haschanged and become rather stable. This trend is similar to that of Japan as a whole..

− 20 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Industrial Shipping Amount( 10 billion Yen )400,000

All over Japan
Total of 13 Prefectures

350,000
300,000
250,000
200,000
150,000
100,000
50,000
0

1960

1965

1970

1975

1980

1985

1990 1992 1994 1996 1998 2000 2002 2004 Year

Note: Source; Ministry of Economy, Trade and Industry

Figure 2-2 Trends in manufacturing shipments in the prefectures concerned

2.1.3

Construction of three routes of Honshu-Shikoku Expressways
Three Honshu-Shikoku Expressways comprising 17 long-span bridges connect Shikoku
Island with Honshu Island, and in comparison with conventional sea transport, the traveling timerequired between the islands has been reduced by one third (Figure2-3). As punctuality has been
improved, as well as time saved, passenger and freight distribution crossing the Seto Inland
Sea has increased significantly. Before its construction, the main means of transport was ferries
and boats, but many passengers changed to using automobiles. One of the key issues, however,is the high cost of tolls, which results from the huge investment required in their construction.

Okayama Pref.

Hyogo Pref.

Seto-Chuo Expressway
Hiroshima Pref.

Nishi-Seto Expressway
Fukuyama-Nishi

Miki JCT
Kobe-Nishi

Okayama JCT
Kurashiki JCT
Hayashima

Nishiseto-Onomichi
Sakaide

AWAJI ISLAND

Sakaide JCT

NarutoKagawa Pref.
Imabari
Imabari-Yunoura

0

10

20

30 km

Tokushima

Kobe-Awaji-Naruto Expressway
Tokushima Pref.

Ehime Pref.

Note: Source; Website of Honshu-Shikoku Expressways Company

Figure 2-3 Construction of three Honshu-Shikoku Expressway routes− 21 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
2.1.4

Fishery Production Industry in the Seto Inland Sea
The Seto Inland Sea has extremely high productivity per unit area of fishery product,
which may be due to the two following reasons: one is essential nutrients needed for the growthof fish and shells that are supplied in sufficient quantities from the many rivers around thesea, and the other is the extremely complex and semi-enclosed geography of the sea with manyislands, straits, nadas and various sizes of bays. Fish-species and the compositions of fishery,
and aquaculture productions in 2005 are shown in Figure 2-4 and 2-5, respectively.
In Figure2-4, the total amount of fishery production was 198,000 tons with its ratio of
Anchovy(18%), White bait(10%) and Sand Eel(10%), being rather large. Moreover, Figure 2-5
shows that total amount of aquaculture product was 286,000 tons with its large ratio of Oysters(47%) and Laver(42%), occupying nearly 90 % of the total.

Seaweed 1％

Others15％

Anchovy
18％

Fishery
198,116 tons
Other fishes （2005）

White bait
10％
Sand eel
10％29％

Octopus 5％
Sepia esculenta
3％

Flat fish Scabbard fish
5％
4％

Note: Source; Ministry of Agriculture, Forestry and Fisheries

Figure 2-4 Fish-species and the composition of fishery production

Bream 1％
Seaweed 4％
Yellowtail 5％

Laver
42％

Others 1％

Aquaculture
286,307 tons
（2005）

Oysters47％

Note: Source; Ministry of Agriculture, Forestry and Fisheries

Figure 2-5 Fish-species composition of aquaculture production− 22 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Production of the coastal fishery amounted to about 490,000 tons in 2004. Trends in fisheryproduction and the composition of fish-species production are shown in Figures 2-6 and 2-7,
respectively.
Figure 2-6 shows that the change in fishery production is similar to that of aquaculture
production. They both increased until around 1985, but since then both have been decreasing.
The reasons for these decreases could be explained by the deterioration of the living environmentof fish and shells caused by water pollution and the destructive reclamation on marine forests
and tidal flats.
Then, Figure 2-7 shows that the decreases in Spotlined Sardine, Anchovy and Sand
Eel and Manila Clam are significant. Various kinds of aquaculture projects have been undertaken
to compensate for the deterioration in the living environment of fish and shells, which are having
a positive effect on the marine production industry in the Seto Inland Sea.

Total fishes
The other fishery animals
Total shell fish
Total seaweed
Total sea aquaculture

Fishery Production( Thousand tons )
900
800
700
600
500
400
300
200
100
0
1965

1970

1975

1980

1985

1990

1995

2000

Note: Source; Ministry of Agriculture, Forestry and Fisheries

Figure 2-6 Trends in fishery production in the Seto Inland Sea− 23 −

2005 Year

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
Fishery Production ( Thousand tons )120,000
Spotlined Sardine
Anchovy

100,000

White Bait
Scabbard Fish

80,000Sand Eel

60,00040,00020,000

0
1965

1970

1975

1980

1985

1990

1995

2000

2005
Year

1980

1985

1990

1995

2000

2005
Year

Fishery Production ( Thousand tons )50,000Horse Mackerel
Mackerel

45,000Flat fish

40,000Manila Clam
Octopus35,00030,00025,00020,00015,00010,000
5,000
0
1965

1970

1975

Note: Source; Ministry of Agriculture, Forestry and Fisheries

Figure 2-7 Trends in fish-species and the composition of the production in the Seto Inland Sea− 24 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

2.1.5

Marine Transport in the Seto Inland Sea
In 1995, both the total tonnage of ships and the total amount of cargo to/from ports
in the Seto Inland Sea reached to 50 % of those for Japan as a whole as shown in Figures 2-8
and 2-9. In 2003 the ratio decreased a little to about 45 % of the domestic total. Many ships
pass through the key straits. For example, the daily average is 824 ships, which includes large
ships and ships with explosives and combustibles, that navigate through the Akashi Strait. On
the other hand, the number of ships that navigate through the Uraga Channel at the mouthof Tokyo Bay is 671.
The number of the ships and the volume of cargo for the prefectures around the Seto
Inland Sea are summarized in Table 2-1. The location of ports and the navigation routes areshown in Figure 2-10.
Obviously, the Seto Inland Sea plays an important role in marine transportation in thewestern part of Japan.
Total tons of shipping( Thousand tons )5,000
All over Japan
4,500
11 pref. facing to the Seto Inland Sea
4,000
3,500
3,000
2,500
2,000
1,500
1,000
500
0
1963 1965

1970

1975

1980

1985

1990

1995

2000

2004
Year

Note: Source; Ministry of Land, Infrastructure and Transport of Japan

Figure 2-8 Tonnage of ships to/from ports of 11 prefectures around the Seto Inland Sea
Amount of ship's cargo( million tons )5,000
All over Japan
4,500
11 pref. facing to the Seto Inland Sea
4,000
3,500
3,000
2,500
2,000
1,500
1,000
500
0
1963 1965

1970

1975

1980

1985

1990

1995

2000

2004
Year

Note: Source; Ministry of Land, Infrastructure and Transport of Japan

Figure 2-9 Volume of cargo to/from ports in 11 prefectures around the Seto Inland Sea− 25 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
Table 2-1 Number of ships and amount of the ship's cargo in the 11 prefectures
around the Seto Inland Sea
Number of Arrival Ships
Tonnage of Ships
Volume of Cargo handled
Arriving(Unit:'000 ships) Entering Ships (million tons)(million tons)
2003
2002
2001
2003
2002
2001
2003
2002
2001

Pref. etc
Fiscal Year
Japan

5,642

5,842

6,015

3,979

3,974

4,001

3,105

3,067

3,094

Osaka

92

96

108

223

226

230

164

160

165

Hyogo

307

313

333

320

327

332

197

211

215

Wakamyama

88

92

88

46

47

48

44

44

45

Okayama

194

197

207

142

140

143

159

159

152

Hiroshima

771

783

779

210

209

221

135

136

140

Yamaguchi

192

205

185

130

128

119

132

127

127

Tokushima

29

34

37

30

29

32

22

21

23

Kagawa

266

271

270

124

127

127

106

106

104

Ehime

342

363

382

156

168

168

91

90

92

Fukuoka

138

134

138

183

182

184

165

161

162

Oita

112

113

116

107

111

105

119

120

125

2,531
(44.9)

2,599(44.5)

2,643(43.9)

1,671(42.0)

1,693(42.9)

1,709(42.7)

1,334(43.0)

1,335(43.5)

1,350(43.6)

Seto Inland Sea( Ratio to Japan % )Note: Source; Ministry of Land, Infrastructure and Transport of Japan

Kyoto Pref.
Hyogo Pref.
Okayama Pref.

Osaka
Pref.

HimejiAmagasaki-nishinomiya-ashiya

Hiroshima Pref.

Yamaguchi Pref.

Hiroshima
Kure

KokuraOnomichi-itozaki ⑥

Fukuoka
Pref. Nakatsu②④③
Takamatsu

Mishima-kawanoe
Niihama

Osaka
Sakai senboku
HannanWakayamashimotsu

Kagawa Pref.
⑧
ImabariToyo
Matsuyama

Kanda

⑤

⑦ Sakaide

Iwakuni

Mitajiri-nakaseki
Tokuyama-kudamatsu
Shimonoseki Onoda
Ube

Higashiharima① KobeOkayamaMizushima
Uno
Fukuyama

Nara
Pref.

Komatsujima

Tokushima Pref. Tachibana

HidakaWakayama Pref.

Ehime Pref.
LegendSpecific
Important port
Important port

Beppu

Oita Pref.

Oita

Uwajima

Tsukumi
Saeki
0

10

20

30 km

Sea lane based by the law①Akashi kaikyo traffic route②Bisan seto east traffic route③Uko east traffic route④Uko west traffic route⑤Mizushima traffic route⑥Bisan seto north traffic route⑦Bisan seto south traffic route⑧Kurushima kaikyo traffic route

Figure 2-10 Ports and navigation routes in the Seto Inland Sea ( March,2004 )− 26 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

2.2 NEGATIVE LOAD ON THE ENVIRONMENT
2.2.1 Reclamation in the Seto Inland Sea
Heavy industries such as steel, petrochemicals, ship-building have been concentrated in
the Seto Inland Sea since the 1950s. In this process many coastal areas have been reclaimed
for industrial sites and port construction.
Table 2-2 and Figure 2-11 show transitions in reclaimed land. The total area of permitted
reclamation is clearly distinct from 1965 to 1972, but decreases drastically from 1973 as shownin Figure 2-12. It was in this year that the " Law Concerning Special Measures for Conservationof the Environment of the Seto Inland Sea (Setouchi Law)" was established.
Several districts around the Seto Inland Sea have been reclaimed. As shown in Table
2-2 the reclaimed area during the period from 1898 to 1924 was about 35 km2, and a further
66 km2 was added from 1925 to 1949. The area of reclamation increased to about 225 km2 from1950 to 1973. The total reclaimed area from 1898 to 2005 came to about 455 km2. Trends inreclaimed areas in the Seto Inland Sea are shown in Figure 2-11.
As shown in Table 2-2 and Figure 2-11 the land area reclaimed in the Seto Inland
Sea after 1898 amounts to 455 km2, which is equivalent to about 70 % of the area of Awaji
Island(the largest island in the Seto Inland Sea). This large scale means that about 20 % ofshallow sea with a depth less than 10 meters has been reclaimed. In the post-war period, thereclaimed area amounts to 354 km2, representing 77.8 % of all reclaimed land. This drastic
reclamation destroyed seagrass and seaweed beds and marine life.
Table 2-2

Reclaimed area in the Seto Inland Sea
Term1898 - 2005
1898 - 1924
1925 - 1949
Items
1950 - 1973
1974 - 2005

Accumulation

Total Area of the
Seto Inland Sea
Reclaimed Area /Total Area
Reclaimed Area /Shallow Zone Area

Area（km2）
455
35
66
225
129

Years
108
27
25
24
32

Average
4.2
1.3
2.8
9.4
4.0

23,203 km2
2.0%
20%(Shallow Zone; less than 10 m in depth)

Area (km2)
250

225

Reclaimed Area
200
150

129

100
66
50

35

0
1898〜1924

1925〜1949

1950〜1973

1974〜2006

Note: Source; Ministry of Land, Infrastructure and Transport and Ministry of theEnvironment of Japan

Figure 2-11 Trends in reclamation in the Seto Inland Sea− 27 −

Year

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
（ha）
4,000

30,000（ha）
After the enforcement of the Law

Reclamed area in each year

3,500

Cumulative reclaimed area

25,0003,000
20,0002,500
15,000

2,000
1,500

10,000Reclaimed area in each year

Cumulative reclaimed area

Before the enforcementof the Law

1,000
5,000
500
0
1965

1975

1985

1995

0
2005 Year

Note 1) Source; Ministry of the Environment of Japan
2) Data for 1971-1973 show the total from January , 1971 to November 1, 1973.
3) Data after 1973 show the total from November 2 of the previous year to November 1,the following year
4) A tentative law was enforced on November 2, 1973
5) Values for 1971-1973 are mean values for the 3 years.

Figure 2-12 Trends in reclaimed areas in the Seto Inland Sea
After the enforcement of the Law Concerning Tentative Measures for Conservation of
the Environment of the Seto Inland Sea (November 2,1973), 4,771 sites with a total area of 12,891 ha
were permitted for reclamation up to November 1, 2005. Indeed from now on, environmental
preservation and protection will be taken into consideration in granting permission for reclamation.
Trends in the reclamation areas in each prefecture and in the Seto Inland Sea are shown in
Figure 2-13 and Table 2-2, respectively. Figure 2-13 shows the present situation of reclamationin Osaka Bay.

− 28 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Kyoto Pref.
Hyogo Pref.

Kobe Airport (1999,272ha)
Kobe (PI-2nd,east,1986,229ha)
Kobe (PI-2nd,west,1988,161ha)
Himeji port (Aboshi,1983,81ha)
Kobe (RI-south,1997,286ha)
Amagasaki-nishinomiya-ashiya
Himeji port
Mizushima port
(1987,113ha)(Mega,1977,79ha)(Tamashima,1986,185ha)
Osaka port
(Hokko-minami,1977,378ha)
Osaka port
Mizushima port
(Nanko-kita,1988,67ha)(Mizushima,1977,52ha)
Sakai Senboku port
(1989,202ha)
Hiroshima port (Itsukaichi,1986,154ha)
Port of Hannan
Hiroshima port (Dejima,1996,129ha)(timber port 1976,51ha)
Port of Hannan
Hiroshima port (Kaida,1978,135ha)(Nishikinohama 1978,243ha)
Minami Osaka (1987,318ha)
Kansai Airport (1987,511ha)
Wakayama shimotsu port (1980,177ha)
Tokushima Airport (2001,60ha)
Kansai Airport (2nd,1999,545ha)
Port of Hannan (Hannan2,1999,142ha)
Komatsujima port (Okisu,1986,119ha)
Komatsujima port (Akaishi,1994,61ha)
Osaka port (Osakashinto,2001,204ha)

Okayama Pref.

Hiroshima Pref.

Osaka Pref.

Yamaguchi
Iwakuni airport (1996,215ha)
Pref.
Ube port Mitajiri port
Shimonoseki(1996,79ha) (1977,70ha)
port (1995,63ha)

Kagawa Pref.

Nara
Pref.

Yanai port (1984,65ha)
Kitakyusyu port (Shinmojikita,1980,63ha)
Kitakyusyu port (Shinmojioki,1994,220ha)
Kanda port (oki,1977,153ha)
Kanda port (No.2area,1977,53ha)
Kanda port (Shinmatsuyama,1995,160ha)
Kitakyusyu port (Hibikinada,1978,216ha)

Fukuoka
Pref.

Tokushima Pref.
Toyo port (1975,351ha)

Wakayama
Pref.

Ehime Pref.

Oita Pref.

0

10

20

30 km

Note: 1) Permitted Reclamation from November 2, 1973 to November 1, 1997
2) Items in parenthesis show permission year was granted and area, in order.
3) Source; Ministry of the Environment of Japan

Figure 2-13 Large scale of reclamation (more than 50 ha) in the Seto Inland Sea− 29 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
Table 2-3 Trends in reclamation areas in each prefecture in the Seto Inland Sea (ha)
Year

Osaka

Hyogo Wakayama Okayama Hiroshima Yamaguchi Tokushima Kagawa

Ehime Fukuoka

Oita

Total

Accumulation

1965

144.3

348.9

65.1

795.6

68.8

24.4

0.8

565

109.7

13.1

61.5

2,197.2

2,197.2

1966

0.1

33.3

84.3

191.3

40.5

11.4

31.6

35.3

5.1

11.3

35.7

479.9

2,677.1

1967

6.3

362.7

2.1

4.9

44.6

159.1

22

15.7

7.9

549.1

55.6

1,230.0

3,907.1

1968

44

2.9

15.3

39

612.3

76.1

28.5

19.4

34.2

109.9

28.7

1,010.3

4,917.4

1969

163.1

768.7

41.4

1,985.70

87.4

165.1

41.8

242.8

28.7

1.8

68.7

3,595.2

8,512.6

1970

182.7

410.5

8.8

5.7

116.8

51

4.5

270.4

49.7

232.3

132.5

1,464.9

9,977.5

1971 - 1973

628.6

1,597.20

42

1,680.60

634.7

353.1

11.6

182.8

297.9

351.4

611.6

6,391.5

16,369.0

1974

6.1

11.5

0.7

38.2

19.9

44.1

23.1

37.4

108.6

59.7

40.9

390.2

16,759.2

1975

0

18.7

15.3

6.3

10

86.5

3.5

34.3

357.9

4

10.5

547.0

17,306.2

1976

62.1

49.5

0.3

2.5

39.8

19

10.9

40.8

24

1.1

16.1

266.1

17,572.3

1977

410.7

96.4

4.2

117.4

7.8

39.1

0.1

39.6

30.3

251.2

43.6

1,040.4

18,612.7

1978

244

6.5

0.4

53

159.5

115.5

7.8

21.4

54.6

255.4

73.2

991.3

19,604.0

1979

20.6

82.6

1.8

3.7

28.2

13.1

2.1

3.7

18.7

3.7

93.4

271.6

19,875.6

1980

0.7

58.4

188.7

17.7

7.3

5.2

1.7

5.6

16

216.3

16.5

534.1

20,409.7

1981

53.8

7.5

5.9

10.1

55.6

25.5

32.9

25.5

60.5

11.5

12.1

300.9

20,710.6

1982

0

13.8

3.4

4.9

5.6

5

3.3

4.9

27.7

1.2

40.9

110.7

20,821.3

1983

21.7

99.3

2

45.3

42.7

110.3

4.9

41.4

49.1

0.3

10.9

427.9

21,249.2

1984

0.1

10.8

0.4

10.5

19.8

82.7

0.5

26.5

5.1

41.2

9.3

206.9

21,456.1

1985

28.8

15.3

8.2

13.4

15

6.8

0.4

15.6

78.3

3.7

12.7

198.2

21,654.3

1986

0

3.6

3.4

1.6

8.9

17.5

119.4

7

87

3.7

14.7

266.8

21,921.1

1987

830.1

364

12.9

191.8

165.2

22.8

1.5

16.8

53.9

6.4

26.1

1,691.5

23,612.6

1988

106.6

171.7

13.2

0.8

16.6

10.4

0.9

27.4

40.8

0.6

10.9

399.9

24,012.5

1989

202.7

39.5

49

9.5

12.3

9.5

23.3

1.9

17.3

5.2

9.1

379.3

24,391.8

1990

0.4

26.2

5.5

1.6

25.2

54.1

18.6

26.4

57.3

8.2

41.7

265.2

24,657.0

1991

0

11.9

43.7

0

45.9

8.7

0.6

11.4

10.2

9

32.3

173.7

24,830.7

1992

1.1

16.2

0

2.2

71.9

9.2

0.6

25.8

7.6

1.2

12

147.8

24,978.5

1993

0.2

22.4

9.7

54.8

33.1

41.1

1.4

29.8

16.6

0

35.2

244.3

25,222.8

1994

0

16.1

11.8

22.5

101.9

15.1

2.2

35.8

18

221.2

17.4

462.0

25,684.8

1995

0

100

46

0.6

18.1

73.1

119.2

10.8

11.7

164.8

21.4

565.7

26,250.5

1996

11.3

17

7.5

6.7

165.3

30.8

35

3.5

33.9

0

4.7

315.7

26,566.2

1997

1

9.4

0.9

4.8

7.3

309.3

0.7

5.7

101.7

0

21.5

462.3

27,028.5

1998

0.9

302.7

1.6

7.5

48.7

3.7

0

15.9

21.3

4.3

58.7

465.3

27,493.8

1999

688.4

274.9

0

1.6

4.9

4.1

0

7

5

6.2

23.9

1,016.0

28,509.8

2000

0.4

6

0

1.1

2.7

63.9

0.3

23.3

40.3

2

6.3

146.3

28,656.1

2001

225.5

0

0

3.4

1.6

39.3

99.7

2.6

20.6

0

5.5

398.2

29,054.3

2002

0

3.5

0

0.8

0.1

4.6

3.3

3.5

15

0

4.4

35.2

29,089.5

2003

0

35.8

1

0

0.7

2.7

0

0.9

1.2

0.3

6.9

49.5

29,139.0

2004

0

1.9

0

0.8

4.8

2.5

0.2

0.2

23.2

3.5

6.8

43.9

29,182.9

2005

-

0.4

0.5

0.6

1.8

35.1

17.9

0.1

8

0.2

11.9

76.5

29,259.4

Total

4,086.3

5,417.7

697.0

5,338.5

2,753.3

2,150.5

676.8

1,883.9

1,954.6

2,555.0

1,745.8

29,259.4

1965 - 1973

1,169.1

3,524.2

259.0

4,702.8

1,605.1

840.2

140.8

1,331.4

533.2

1,268.9

994.3

16,369.0

1974 - 2005

2,917.2

1,893.5

438.0

635.7

1,148.2

1,310.3

536.0

552.5

1,421.4

1,286.1

751.5

12,890.4

Note: 1) Source; Ministry of the Environment of Japan
2) Data for 1971-1973 show the total from January 1 in 1971 to November 1 in 1973
3) Data after 1973 show the total from November 2 in the previous year to November 1 in the following year.

− 30 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Nishinomiya city

Ashiya city

Amagasaki city

Amagasaki・
Nishinomiya・
Ashiya Port

Kobe city

Osaka city

Kobe Port
Osaka Port

Reclamation area more than 50ha after
the enforcement of the Law for Environmetal
Conservation of the Seto Inland Sea

Sakai Senboku Port

Sakai city

・Port of Hannan (timber port, 1976) 51ha
・Osaka port (Hokkou minami, 1977) 378ha
・Hannan port (Nishikinohama, 1978) 243ha

Takaishi city

・Kobe port (Port Island east, 1986) 229ha
・Amagasaki・Nishinomiya・Ashiya port (1987) 113ha

rt o
fH
an
na
n

・Kansai Airport (1987) 511ha
・Minami Osaka (Rinku town 1987) 318ha
・Osaka port (Nanko kita, 1988) 67ha
・Kobe port (Port Island west, 1988) 161ha

Po・Sakai Senboku port (1989) 203ha
・Kobe port (Rokko Island south, 1997) 286ha

Izumiotsu city

Kishiwada city

・Port of Hannan (Hannan2, 1999) 142ha

1600〜1868

t
or
ri p
iA
sa

・Kobe Airport (1999) 272ha
・Osaka port (Yumeshima,2001) 204ha( Edo Period )Kaizuka city

1868〜1912( Meiji Period )1912〜1925nKa( Taisho Period )1925〜1945
1946〜1979
Tajiri cho
Sennan city

Completion untill 2007
Permitted area untill
the end of Nov.,1997

Note: Source; The Association for the Environmental Conservation of the Seto Inland Sea

Figure 2-14 Present situation of reclamation in the Osaka Bay− 31 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
2.2.2 Extraction of Gravel and Sand from the Bottom of Seto Inland Sea
Gravel and sand are important raw materials for building construction. The amount ofthem extracted from 11 prefectures around the Seto Inland Sea represents 8 % of Japanese
consumption, in which about 80 % of gravel and sand are extracted from the bottom of thesea. The amount represents about 55 % of such material extracted from the bottom of the sea.
Trends in the amount of gravel and sand extracted from the bottom of the Seto Inland
Sea are shown in Figure 2-15. In the last two or three years, the amount extracted from thesea has been decreasing, which reflects the prohibitive regulations established in almost all
prefectures around the Seto Inland Sea.

Extracted Amount of Gravel and Sand
( Thousand m3 )Others (All over Japan)
Sea (All over Japan)
Others (11prefectures faced to the Seto Inland Sea)
Sea (11prefectures faced to the Seto Inland Sea)

180,000
150,000
120,000
90,00060,00030,000
0
1971

1975

1980

1985

1990

1995

2000

Note: Source; Ministry of Economy, Trade and Industry of Japan

Figure 2-15 Gravel and sand extracted from the bottom of the Seto Inland Sea− 32 −

2005
Year

ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

2.3 CHANGES IN WATER AND SEDIMENT QUALITY
2.3.1. Water quality
The sea is greatly influenced by incoming rivers due to its relatively shallow depth.
Fluctuations in water temperature, salinity and nutrient concentration sometimes make the areasusceptible to unusual events, such as red tides.
During the period of high economic growth after World War II, large parts of theshallow coastal areas were reclaimed in order to construct industrial and residential zones.
Large quantities of industrial effluent, as well as domestic sewage, were released into the sea.
Water quality rapidly degraded and also triggered frequent red tides, resulting in extensive
damage to fisheries. In Japan, including the Seto Inland Sea, COD (Chemical Oxygen Demand)is used as an indicator to establish reduction targets for the total quality of organic pollutants
discharged from factories, sewage treatment plants and domestic households, and effluent restrictions
and guidance were also implemented. Recently, total nitrogen (TN) and phosphorous (TP)concentration have also been used as indicators for water quality.
The horizontal distributions of salinity, COD, TN, TP and Chlorophyll a (Chla) in surface
water during the summer season are shown in Figures 2-16 to 20. Low salinity was observedin the inner part of Osaka Bay and Hiroshima Bay, while high COD, Total-N and Total-P wereobserved in the inner part of Osaka Bay, Hiroshima Bay and Beppu Bay. High Chla were also
observed in the inner part of Osaka Bay, the western part of the Kii-Channel, the northernpart of Harima-Nada and Hiroshima Bay.

Hyogo Pref.
Okayama Pref.

Osaka
Pref.

Hiroshima Pref.

Kagawa Pref.
Yamaguchi Pref.
Tokushima Pref.

FukuokaPref.

Ehime Pref.

less than 28
28〜30
30〜31
31〜32
32〜33
more than 33

Oita Pref.

0

10

20

Wakayama
Pref.

30 km

Note: Source; Ministry of the Environment of Japan (2004)

Figure 2-16 Horizontal distribution of salinity in the surface layer during the summer season, 2003

− 33 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
Hyogo Pref.
Okayama Pref.

Osaka
Pref.

Hiroshima Pref.

Kagawa Pref.
Yamaguchi Pref.
Tokushima Pref.

FukuokaPref.

Wakayama
Pref.

Ehime Pref.
less than 2 mg/L
2〜3 mg/L

Oita Pref.

3〜4 mg/L
more than 4 mg/L

Note: Source; Ministry of the Environment of Japan (2004)

Figure 2-17 Horizontal distribution of COD in the surface layer during the summer season, 2003

Hyogo Pref.
Okayama Pref.

Osaka
Pref.

Hiroshima Pref.

Kagawa Pref.
Yamaguchi Pref.
Tokushima Pref.

FukuokaPref.

Wakayama
Pref.

Ehime Pref.
less than 0.2 mg/L
0.2〜0.3 mg/L

Oita Pref.

0.3〜0.6 mg/L
0.6〜1.0 mg/L
more than 1.0 mg/L

Note: Source; Ministry of the Environment of Japan (2004)

Figure 2-18 Horizontal distribution of TN in the surface layer during the summer season, 2003

− 34 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Hyogo Pref.
Okayama Pref.

Osaka
Pref.

Hiroshima Pref.

Kagawa Pref.
Yamaguchi Pref.
Tokushima Pref.

FukuokaPref.

Wakayama
Pref.

Ehime Pref.
less than 0.02 mg/L
0.02〜0.03 mg/L

Oita Pref.

0.03〜0.05 mg/L
0.05〜0.09 mg/L
more than 0.09 mg/L

Note: Source; Ministry of the Environment of Japan (2004)

Figure 2-19 Horizontal distribution of TP in the surface layer during the summer season, 2003

Hyogo Pref.
Okayama Pref.

Osaka
Pref.

Hiroshima Pref.

Kagawa Pref.
Yamaguchi Pref.
Tokushima Pref.

FukuokaPref.

Wakayama
Pref.

Ehime Pref.

Oita Pref.

0

10

20

30 km

Note: Source; Ministry of Land, Infrastructure and Transport Japan (2004)

Figure 2-20 Horizontal distribution of Chla in the surface layer during the summer season, 2003

− 35 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
The definitions of environmental standards for water quality are as shown in Tables
2-4(a) and 2-4(b). Further, the assigned sea zones, each classified according to the category of
their environmental standard, are shown in Figures 2-21 and 22.
Table 2-4(a)Environmental standards relating to the conservationof the living environment of the sea areas

Category

A

B

C

Water Use

Fishery Class 2 ・industrial water andall uses listed in C

Conservation ofliving environment

Items

Fishery Class 1 ･bathing ･ conservationof naturalenvironment ･ anduses listed in B - CpH

7.8〜8.3

7.8〜8.3

7.0〜8.3

2 or less3 or less8 or less

7.5 or more

5 or more

2 or more

Below 1,000――

Not detectable

Not detectable―

Chemical Oxygen Demand(COD)(mg/l)
Dissolved Oxygen (DO)(mg/l)
Coliform group number(MPN/100ml)
n-hexane extract（oil content etc.）(mg/l)

Remarks : 1. Standard values are for daily averages.
2. For Fishery Class 1, the standard for total coliform in waters used to raise oysters for raw
consumption is 70 MPN/100 mL or less.
（Notes） 1. Conservation of the natural environment: Conservation of sightseeing and other environments
2. Fishery Class 1: For marine products such as red sea bream, yellowtail, and seaweed, and marine
products for Fishery Class 2. Fishery Class 2: Marine products such as mullet and dried seaweed
3. Conservation of the environment: Degree to which the day-to-day lives of the population are notdisrupted (including walks along the beach and the like).
4. Source; Water Quality Conservation for Enclosed Water Bodies in Japan 2005 (International EMECS
Center)Table 2-4(b)Environmental standards relating to the conservationof the living environment of the sea areas

Category

Ⅰ

Ⅱ

Ⅲ

Ⅳ

Water Use

Conservation of
the naturalenvironment anduses listed in
Ⅱ-Ⅳ (except
Fishery Classes
2 and 3)

Fishery Class1, bathing , anduses listed in
Ⅲ- Ⅳ (except
Fishery Classes
2 and 3)

Fishery Class 2
and uses listedin Ⅳ (except
Fishery Class 3)

Fishery Class 3,
industrial water,
and conservationof habitableenvironments formarine biota

Total nitrogen（mg/l)

0.2 or less

0.3 or less

0.6 or less1 or lessTotal phosphorus (mg/l)

0.02 or less0.03 or less0.05 or less0.09 or less

Items

Remarks 1: Standard values are for annual average values.
2: Specified aquatic areas are at risk for marine phytoplankton blooms
Notes)
1. Conservation of the natural environment: Conservation of sightseeing and other environments
2. Fishery Class 1: A large variety of fish, including benthic fish and shellfish, are caught in good balance
and in a stable manner.
Fishery Class 2: Marine products (mainly fish) are caught with the exception of some benthic fish andshellfish
Fishery Class 3: Specific types of marine products highly resistant to pollution mainly caught
3. Conservation of habitable environments for marine biota: Level where bottom-dwelling organisms canmake their habitat all year-round
4. Source; Water Quality Conservation for Enclosed Water Bodies in Japan 2005 (International EMECS
Center)− 36 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Kyoto Pref.

Hyogo Pref.
Osaka
Pref.

Okayama Pref.

Hiroshima Pref.
Nara
Pref.
Kagawa Pref.

Yamaguchi Pref.

Tokushima Pref.
Wakayama
Pref.

Ehime Pref.
FukuokaPref.
Oita Pref.

Legendcategory A
category B
category C

0

10

20

30 km

Figure 2-21 The assigned sea zones classified as categories, A to C, of environmental standards

Kyoto Pref.

Hyogo Pref.
Okayama Pref.

Osaka
Pref.

Hiroshima Pref.
Nara
Pref.
Kagawa Pref.

Yamaguchi Pref.

Tokushima Pref.
Ehime Pref.

Wakayama
Pref.

FukuokaPref.
LegendOita Pref.

categoryⅠ
categoryⅡ
categoryⅢ
categoryⅣ
0

10

20

30 km

Figure 2-22 The assignment sea zones classified as categories, I to IV, of environmental standards− 37 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
2.3.2. Trends in water quality
Transparency, COD, Total-N and Total-P in the Seto Inland Sea are shown in Figures
2-23 to 26. Transparency has slightly increased and the level of COD is stable or slightly
increased. Total-N and Total-P have declined a little.
Transparency (m)
12.5

10.0
7.5
5.0
2.5
0.0

1975

1980

1985

1990

1995

2000

Note: 1) Yearly mean of 18 nada and bays in the Seto Inland Sea
2) Source; Ministry of the Environment of Japan (2005)

2005
FiscalYear

Figure 2-23 Change in transparency in the Seto Inland Sea

COD (mg/L)
3.0

2.5
2.0
1.5
1.0
0.5
0.0

1975

1980

1985

1990

1995

2000

Note: 1) Yearly mean concentration of 18 nada and bays in the Seto Inland Sea
2) Source; Ministry of the Environment of Japan (2005).

2005
FiscalYear

Figure 2-24 Change in COD concentration in the Seto Inland Sea

Total Nitrogen (mg/L)
0.5

0.4
0.3
0.2
0.1
0.0

1975

1980

1985

1990

1995

2000

Note: 1) Yearly mean concentration of 18 nada and bays in the Seto Inland Sea
2) Source; Ministry of the Environment of Japan (2005).

Figure 2-25 Change in TN concentration in the Seto Inland Sea− 38 −

2005
FiscalYear

ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Total Phosphorus (mg/L)
0.04

0.03
0.02
0.01
0.00

1975

1980

1985

1990

1995

2000

Note: 1) Yearly mean concentration of 18 nada and bays in the Seto Inland Sea
2) Source; Ministry of the Environment of Japan (2005)

2005
FiscalYear

Figure 2-26 Change in TP concentration in the Seto Inland Sea

2.3.3 Sediment quality and Benthos
Generally, sediment quality in the sea is deteriorating, particularly in areas with stagnant
water or small tidal current. The horizontal distributions of mud content, COD, Ignition loss,
TN, TP and Oxidation Reduction Potentials (ORP) in sediments are shown in Figures 2-27 to
32. High COD, Ignition Loss, TN and TP were observed at Osaka Bay, Harima-Nada, Hiuchi
Nada, Hiroshima Bay, southwestern part of Suo-Nada and Beppu Bay. Obviously, low ORP was
observed in these areas. The horizontal distributions of individuals, numbers of species anddiversity index of macro-benthos in sediments are shown in Figures 2-33 to 35. High numbersof individuals and of macro-benthos species were observed at Bisan-Seto, in the western partof Bingo-Nada and Aki-Nada. Low biodiversity was observed in Osaka Bay, Harima-Nada, Hiuchi
Nada, Hiroshima Bay, the southwestern part of Suo-Nada and Beppu Bay.
In the past, observations of bottom sediment throughout the Seto Inland Sea wereconducted three times by the Ministry of Environment of Japan. The first one was from 1981
to 1987, the second from 1991 to 1996, and the third from 2001 to 2005. In comparing the mostrecent data with the previous data, no parameters except for ORP changed over the 20 year
period in any of the areas. Also, there was no area where sediment quality had deteriorated,
and improvement in sediment quality was observed in all areas, particularly in Suo-Nada. Basedon benthos, three categories for the area can be assigned according to the number of species
and the diversity of macro-benthos. The first one is an area where macro-benthos is rich, suchas Aki-Nada. The second is an area where macro-benthos is poor, such as in Beppu-Bay,
Hiroshima Bay and Osaka Bay. The third is an area where the situation of macro-benthos is
between the first two. In comparing the most recent data with the previous data obtained ten
years ago, statistically significant differences in individuals and the numbers of species of macro-benthos
can be observed at Harima-Nada (decrease in individuals); Hiuchi-Nada (decrease in individuals
and numbers of species); Kii-Channel (decrease in numbers of species); Bisan-Seto (increase in
numbers of species); Bungo-Channel (increase in numbers of species); and Aki-Nada (increase inindividuals and numbers of species). In comparing the results of the observation performed by
the Fisheries Agency 20 years ago, it was thought that the number of species and the diversityof macro-benthos had decreased or shown no change in most areas.
Based on the correlation between water and sediment environments, it is thought that
because of human activities and the small tidal current, it is easy to accumulate pollutants inthe sea regions with a high content of sludge in the sediment, although the correlation among
the quality of water and sediment and the environment of aquatic animals and plants are notcompletely understood. With respect to water quality in such sea regions, transparency is
generally small and COD concentration in summer is especially high.

− 39 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
Hyogo Pref.
Okayama Pref.

Osaka
Pref.

Hiroshima Pref.

Kagawa Pref.
Yamaguchi Pref.
Tokushima Pref.
Wakayama
Pref.
FukuokaPref.

Ehime Pref.
more than 70％
50〜70％
30〜50％

Oita Pref.

10〜30％
less than 10％

Note: 1) Yearly mean concentration from 2001 to 2005 in the Seto Inland Sea
2) Source; Ministry of the Environment of Japan (2001-2005)

Figure 2-27 Horizontal distribution of mud content

Hyogo Pref.
Okayama Pref.

Osaka
Pref.

Hiroshima Pref.

Kagawa Pref.
Yamaguchi Pref.
Tokushima Pref.
Wakayama
Pref.
FukuokaPref.

Ehime Pref.
more than 30 mg/g
20〜30 mg/g
10〜20 mg/g

Oita Pref.

5〜10 mg/g
less than 5 mg/g

Note: 1) Yearly mean concentration from 2001 to 2005 in the Seto Inland Sea
2) Source; Ministry of the Environment of Japan (2001-2005)

Figure 2-28 Horizontal distributions of COD concentration in sediments− 40 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Hyogo Pref.
Okayama Pref.

Osaka
Pref.

Hiroshima Pref.

Kagawa Pref.
Yamaguchi Pref.
Tokushima Pref.
Wakayama
Pref.
FukuokaPref.

Ehime Pref.
more than 16 %12〜16 %
8〜12 %

Oita Pref.

4〜8 %less than 4 %Note: 1) Yearly mean concentration from 2001 to 2005 in the Seto Inland Sea
2) Source; Ministry of the Environment of Japan (2001-2005)

Figure 2-29 Horizontal distribution of ignition loss in sediments

Hyogo Pref.
Okayama Pref.

Osaka
Pref.

Hiroshima Pref.

Kagawa Pref.
Yamaguchi Pref.
Tokushima Pref.
Wakayama
Pref.
FukuokaPref.

Ehime Pref.
more than 2.0 mg/g
1.5〜2.0 mg/g
1.0〜1.5 mg/g

Oita Pref.

0.5〜1.0 mg/g
less than 0.5 mg/g

Note: 1) Yearly mean concentration from 2001 to 2005 in the Seto Inland Sea
2) Source; Ministry of the Environment of Japan (2001-2005)

Figure 2-30 Horizontal distribution of TN concentration in sediments− 41 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
Hyogo Pref.
Okayama Pref.

Osaka
Pref.

Hiroshima Pref.

Kagawa Pref.
Yamaguchi Pref.
Tokushima Pref.
Wakayama
Pref.
FukuokaPref.

Ehime Pref.
more than 0.60 mg/g
0.45〜0.60 mg/g

Oita Pref.

0.30〜0.45 mg/g
0.15〜0.30 mg/g
less than 0.15 mg/g

Note: 1) Yearly mean concentration from 2001 to 2005 in the Seto Inland Sea
2) Source; Ministry of the Environment of Japan (2001-2005)

Figure 2-31 Horizontal distribution of TP concentration in sediments

Hyogo Pref.
Okayama Pref.

Osaka
Pref.

Hiroshima Pref.

Kagawa Pref.
Yamaguchi Pref.
Tokushima Pref.
Wakayama
Pref.
FukuokaPref.

Ehime Pref.
more than -100 mV-100〜0 mV
0〜100 mV

Oita Pref.

100〜200 mV
less than 200 mV

Note: 1) Yearly mean concentration from 2001 to 2005 in the Seto Inland Sea
2) Source; Ministry of the Environment of Japan (2001-2005)

Figure 2-32 Horizontal distribution of Oxidation Reduction Potential in sediments− 42 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Hyogo Pref.
Okayama Pref.

Osaka
Pref.

Hiroshima Pref.

Kagawa Pref.
Yamaguchi Pref.
Tokushima Pref.
Wakayama
Pref.
FukuokaPref.

Ehime Pref.
more than 120 nos/0.1m2
100〜120 nos/0.1m2
80〜100 nos/0.1m2

Oita Pref.

60〜80 nos/0.1m2
less than 60 nos/0.1m2

Note: 1) Yearly mean concentration from 2001 to 2005 in the Seto Inland Sea
2) Source; Ministry of the Environment of Japan (2001-2005)

Figure 2-33 Horizontal distribution of individual macro-benthos in sediments

Hyogo Pref.
Okayama Pref.

Osaka
Pref.

Hiroshima Pref.

Kagawa Pref.
Yamaguchi Pref.
Tokushima Pref.
Wakayama
Pref.
FukuokaPref.

Ehime Pref.
more than 40
30〜40
20〜30

Oita Pref.

10〜20
less than 10

Note: 1) Yearly mean concentration from 2001 to 2005 in the Seto Inland Sea
2) Source; Ministry of the Environment of Japan (2001-2005)

Figure 2-34 Horizontal distribution of the number of species of macro-benthos in sediments− 43 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
Hyogo Pref.
Okayama Pref.

Osaka
Pref.

Hiroshima Pref.

Kagawa Pref.
Yamaguchi Pref.
Tokushima Pref.
Wakayama
Pref.
FukuokaPref.

Ehime Pref.
more than 3.00
2.50〜3.00

Oita Pref.

2.00〜2.50
1.50〜2.00
less than 1.50

Note: 1) Yearly mean concentration from 2001 to 2005 in the Seto Inland Sea
2) Source; Ministry of the Environment of Japan (2001-2005)

Figure 2-35 Horizontal distribution of the diversity index of macro-benthos in sediments− 44 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

2.4 OCCURRENCE OF RED TIDES
2.4.1

Types of harmful algal blooms
In eutrophicated coastal areas such as the Seto Inland Sea, microalgal populations growdensely by virtue of rich nutrients and sometimes form algal blooms accompanying water
discoloration. Some microalgal species have a negative effect on marine organisms as a resultof bloom formation. The microalgae giving negative impacts are called "harmful algae", and thephenomena of increasing populations of harmful algae are designated as harmful algal blooms(HABs) (Hallegraeff 1993).
HABs are categorized into four types and these HABs are summarized in Table 2-5.
Biomass blooms are composed of basically non-toxic species; however, blooms can grow sodense that they indiscriminately kill fish and invertebrates due to oxygen depletion as a resultof decomposition. In toxic blooms, their potent toxins are accumulated mainly in bivalves throughthe food chain by ingestion of toxic microalgae through filtration, and these toxins cause avariety of gastrointestinal and neurological illnesses in humans if they consume toxin-contaminatedbivalves. Shellfish poisoning can occur under low cell densities of toxic species without water
discoloration as low as 100 cells L-1 or less. Noxious red tides are basically non-toxic to humans,
but harmful to fish and invertebrates causing mass mortalities, especially in intensive aquaculture
in coastal areas. Diatom blooms have a negative impact on "Nori" (Porphyra, red alga) aquaculture
in coastal areas during the season from autumn to spring as a result of the deprivation ofnutrients (mainly nitrogen) in water columns, and this causes bleaching of Porphyra thalli. Bleaching
lowers the quality and price of "Nori" (seaweed) products (Manabe and Ishio 1991, Nagai 2000).
Since "Nori" is a big aquaculture industry in Japan, diatom blooms are an economic annoyancein "Nori" aquaculture areas during the seaweed-growing and harvesting season. It is very difficult
to estimate the fishery damage on the basis of monetary value of "Nori" bleaching in aquaculture
by diatom blooms. It is also the case of bivalve aquaculture when harvest regulation is
implemented due to toxic blooms. In the Seto inland Sea, eutrophication is closely linked to redtides, especially of the noxious and biomass bloom types.

Table2-5 Types of harmful algal blooms in the coastal sea (after Hallegraeff 1993,
modified by adding diatom blooms against Porphyra aquaculture)
Type of Red-tide1) Biomass red tides(Biomass blooms)

Biomass red tides are basically harmless water discolorations;however, under exceptional circumstances , they sometimes become sodense that they indiscriminately kill fish and invertebrates due tooxygen depletion.
Causative species:
Gonyaulax polygramma, Noctiluca scintillans,
Scrippsiella trochoidea, Trichodesmium erythraeum2) Toxic blooms

Toxic blooms cause shellfish poisoning and fishfood poisoning as aresult of the accumulation of toxins contained in microalgae throughthe food chain . Low cell densities (< 1 cell mL - 1 ) can bring aboutshellfish poisoning.
Poisoning and causative species- Paralytic Shellfish Poisoning (PSP):
Alexandrium tamarense, A. catenella, A. minitum,
A. tamiyavanichii, Gymnodinium catenatum,
Pyrodinium bahamense- Diarrhetic Shellfish Poisoning (DSP):
Dinophysis fortii, D. acuminata, D. caudata, D. mitra,
D. rotundata, Prorocentrum lima
- Amnesic Shellfish Poisoning (ASP):
Pseudo-nitzschia multiseries, P. australis, P. delicatissima- Neurotoxic Shellfish Poisoning (NSP):
Karenia brevis- Ciguatera Fishfood Poisoning (CFP)
Gambierdiscus toxicus− 45 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
3) Noxious red tides

Red tides of this type are non-toxic to humans, but harmful to fish andinvertebrates, especially in intensive aquaculture sites, causing massmortalities.
Causative species:
Chattonella antiqua, C. marina, C. ovata, Pseudochattonella
verruculosa, Heterosigma akashiwo, Heterocapsa
circularisquama, Karenia mikimotoi, Cochlodinium
polykrikoides, Chrysochromulina polylepis, Prymnesium parvum4) Diatom blooms

Diatoms are usually important as primary producers; however, diatom
blooms have a negative im pact on 'Nori' (Porphyra) aquaculture
between autumn and spring by bleaching Porphyra thalli, which lowers
the quality and price of Nori products.
Causative species:
Eucampia zodiacus, Coscinodiscus wailesii, Chaetoceros spp.,
Skeletonema costatum, Thalassiosira spp., Rhizosolenia
imbricata

2.4.2 Occurrences of Red-tide and fishery damages in the Seto Inland Sea
During the two decades of the 1960s and 1970s, the Japanese economy grew rapidly.
In 1960 and 1965, the beginning of the high-growth period of the Japanese economy, the total
number of occurrences of red-tide was less than 50 per year in the Seto Inland Sea (Okaichi1997). Figure 2-36 represents the occurrences of red tides (incidents per year) in the Seto Inland
Sea from 1970 to 2005 (Fisheries Agency of Japan 2000, 2006). The total number of occurrences
was 79 in 1970, showing a marked increment to a maximum of 299 per year in 1976. Afterthe peak in 1976, the number of such incidents demonstrated a trend to clearly decrease toaround 100 per year (around 10 accompanying fishery damages), and this level has been
maintained to the present.

Incidents
300

Total Incidents
Fisheries damage

299
269

250

255

210

196

200

172

164

150

188
171 166 165

151

136

170 162
130
107

100
50
0

117 124135
108 107 100 105

79
35 39 28

1970

18 17

29

18

27

15 17

8

8

18 13

5

8

14 12 10

6

1980

7

1990

5

6

6

105 112 106

96 90 892

10 12 11 11

7

97 89

10

2000

7

8

106

8

118

13

115

7

2005 Year

Figure 2-36 Occurrence of red tides in the Seto Inland Sea from 1970 to 2005.
Short columns indicate incidents with fishery damage such as fish-kills

The distribution of red tides in the Seto Inland Sea from 1960 to 2000 is depicted in
Figure 2-37. In 1960, there were few occurrences of red tides (18 cases), and the area involved
was small. In the 1970s and 1980s, large-scale red tides occurred frequently, especially during
the summer season. In extreme cases, some red tides covered almost the whole area of the
Nada and Bay, such as Osaka Bay, Harima-Nada, Hiuchi-Nada, and Suo-Nada. In the 1990s andthereafter, the scale and period of red tides appeared to become smaller and shorter.

− 46 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Kyoto Pref.
Hyogo Pref.
Okayama Pref.

Harima-nada

Hiroshima Pref.

Osaka
bay

Osaka
Pref.
Nara
Pref.

Bingo-nada

Kagawa Pref.

Hiroshima bay

Yamaguchi Pref.

Hiuchi-nada

Tokushima Pref.

Wakayama
Pref.

Suo-nada

FukuokaPref.

Iyo-nada

Ehime Pref.

Oita Pref.

0

10

20

1960

30 km

Kyoto Pref.
Hyogo Pref.
Okayama Pref.

Harima-nada

Hiroshima Pref.

Osaka
bay

Osaka
Pref.
Nara
Pref.

Bingo-nada

Kagawa Pref.

Hiroshima bay

Yamaguchi Pref.

Hiuchi-nada

Tokushima Pref.

Wakayama
Pref.

Suo-nada

FukuokaPref.

Iyo-nada

Ehime Pref.

Oita Pref.

0

10

20

1970

30 km

Kyoto Pref.
Hyogo Pref.
Okayama Pref.

Harima-nada

Hiroshima Pref.

Osaka
bay

Osaka
Pref.
Nara
Pref.

Bingo-nada

Kagawa Pref.

Hiroshima bay

Yamaguchi Pref.

Hiuchi-nada

Tokushima Pref.

Wakayama
Pref.

Suo-nada

FukuokaPref.

Iyo-nada

Ehime Pref.

Oita Pref.

0

10

20

1980

30 km

− 47 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
Kyoto Pref.
Hyogo Pref.
Okayama Pref.

Harima-nada

Hiroshima Pref.

Osaka
bay

Osaka
Pref.
Nara
Pref.

Bingo-nada

Kagawa Pref.

Hiroshima bay

Yamaguchi Pref.

Hiuchi-nada

Tokushima Pref.

Wakayama
Pref.

Suo-nada

FukuokaPref.

Iyo-nada

Ehime Pref.

Oita Pref.

0

10

20

1990

30 km

Kyoto Pref.
Hyogo Pref.
Okayama Pref.

Harima-nada

Hiroshima Pref.

Osaka
bay

Osaka
Pref.
Nara
Pref.

Bingo-nada

Kagawa Pref.

Hiroshima bay

Yamaguchi Pref.

Hiuchi-nada

Tokushima Pref.

Wakayama
Pref.

Suo-nada

FukuokaPref.

Iyo-nada

Ehime Pref.

Oita Pref.

0

10

20

2000

30 km

Figure 2-37 Decadal changes in the distribution of red-tide in the Seto Inland Sea

The representative microalgae causing noxious red tides in the Seto Inland Sea are
Chattonella antiqua Hada (Ono), Chattonella marina (Subrahmanyan) Hara et Chihara, Chattonella
ovata Hara et Chihara, Heterosigma akashiwo(Hada) Hada ex Hara et Chihara (Raphidophyceae),
Noctiluca scintillans (Macartney) Kofoid, Karenia mikimotoisy (Miyake et Kominami ex Oda) Hansen
et Moestrup, Heterocapsa circularisquama Horiguchi, and Cochlodinium polykrikoides Margalef(Dinophyceae) (Figure 2-38). The top three most noxious species in order of the amount of fisherydamage are C. antiqua, K. mikimotoi and H. circularisquama in the Seto Inland Sea.

− 48 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Figure 2-38 Noxious red tide microalgae in the Seto Inland Sea
Fish-killing raphidophyte (A-D), Chattonella antiqua (A), C. marina (B),a cyst of Chattonella attaching to
diatom frustule (C), Heterosigma akashiwo (D), and red tide forming dinoflagellates (E-H), biomass-bloom
forming Noctiluca scintillans (E), fish-killing Karenia mikimotoi (F), bivalve-killing Heterocapsa
circularisquama (G), and fish-killing Cochlodinium polykrikoides (H). Scale bar, 20μm except for E (100μm).

Figure 2-39 illustrates the number of red tides and those with fishery damage caused
by each red-tide organism mentioned above from 1973 to 2004, according to data from the
Fisheries Agency of Japan (2000, 2005). Karenia mikimotoi, H. akashiwo and N. scintillans showeda high number of red-tide occurrences in the Seto Inland Sea in the 1970s. However, the numberof incidents caused by these species markedly decreased thereafter. Red tides from raphidophytes
C. antiqua and C. marina were common during the summers of the 1970s and 1980s, but they
decreased in the 1990s and thereafter. In recent years, Chattonella red tides have shown a tendency
to revive, newly joining another fish-killing species C. ovata. The long-term trend shows agenerally decreasing tendency, except for H. circularisquama, which was first detected in 1995
in the Seto Inland Sea (Hiroshima Bay), although this species first appeared and formed thefirst red tide accompanied by mass mortalities of short-necked clam in 1988 in the Uranouchi
Inlet, on the Pacific coast of Shikoku. Red tides of C. polykrikoides have appeared to increase inrecent years, although there are now only 5 incidents per year or less. In the Seto Inland Sea,a bloom of this species was first noticed in Harima-Nada in 1985 (Yuki & Yoshimatsu 1989).
Heterosigma akashiwo and N. scintillans form red tides more frequently, but rarely cause fisherydamage in general. On the other hand, red tides of Chattonella spp. (C. antiqua, C. marina andC. ovata), K. mikimotoi, H. circularisquama and C. polykrikoides tend to accompany mass mortalities
of fish and bivalves more frequently.

− 49 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA

Figure 2-39 Number of red tides (open circle) and those with fisherydamage (closed circle) caused by Cochlodinium polykrikoides,
Chattonella spp., Karenia mikimotoi, Heterosigma akashiwo,
Heterocapsa circularisquama, and Noctiluca scintillans in the
Seto Inland Sea from 1973 to 2004

− 50 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Figure 2-40 represents fishery damage to aquaculture (in Japanese yen) from 1970 to2004 resulting from noxious red tides and causative organisms responsible for > 80% of damage
each year in the Seto Inland Sea according to data from the Fisheries Agency (2000, 2005).
Chattonella spp. (C. antiqua, C. marina and C. ovata) are concluded to be the most harmful redtide organisms as indicated by Figure 2-40. Notably in the summer of 1972, C. antiqua killed 14.
2 million cultured yellowtails, which were worth about 7.1 billion yen in Harima-Nada. This
figure is the worst in Japan. During the period from 1990 to 2002, the fishery damage withfish kill by Chattonella was less than 0.1 billion yen per year, but Chattonella red tides recurred
thereafter to make fish-kill in the Seto Inland Sea in 2003 and 2004. Karenia mikimotoi has
continuously resulted in fishery damage since 1979. The killing of oysters by the dinoflagellate
H. circularisquama first occurred in Hiroshima Bay in 1995, and again in 1997. The red tide of
H. circularisquama in 1998 caused mass mortality of oysters worth 3.9 billion yen in Hiroshima
Bay, which was the second worst fishery damage in the Seto Inland Sea. However, as a longterm trend, the amount of fishery damage appears to be showing a tendency to decrease,
except for the 1998 case of oyster aquaculture by H. circularisquama. Other than these majororganisms, a red tide caused by the dinoflagellate Gonyaulax polygramma Stein in 1994 is a casewith a rather large fishery damage of 0.8 billion yen in the Seto Inland Sea (Koizumi et al.
1996a). Fish-kills by C. polykrikoides have been observed since 1985 (Yuki & Yoshimatsu 1989),
but the amount of damage and the scale of the red-tides have been smaller than those fromother major species. However, in the summer of 2004, fish-kills by C. polykrikoides first exceeded
0.1 billion yen (0.16 billion yen) in Iwamatsu Bay in Ehime Prefecture in the Bungo Channel,
the Seto Inland Sea (Fisheries Agency 2005). This species has been notorious for the extreme
harmfulness of its fish-kills in the Kyushu area (the largest damage amounted to some 4 billion
yen in Yatsushiro Sea in the summer of 2000; Kim et al. 2004, Matsuoka and Iwataki 2004)
and especially in Korean coastal waters (largest damage of 76.4 billion Korean won in the summerof 1995; Yoon 2001, Kim et al. 2002), and hence more attention must be paid to monitoring of
C. polykrikoides in the Seto Inland Sea.

Figure 2-40 Fishery damage to aquaculture caused by noxious red tides in the Seto
Inland Sea from 1970 to 2004
Illustrations indicate causative microalgae responsible for > 80% of the total damage each year. C:
Chattonella spp. (C. antiqua, C. marina and C. ovata), K: Karenia mikimotoi, H: Heterocapsa
circularisquama, G: Gonyaulax polygramma, Coc: Cochlodinium polykrikoides.

− 51 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
2.4.3 Characteristics of representative red-tide organisms in the Seto Inland Sea
Table 2-6 describes the first detection of red tides, together with notes on the originof the five major red-tide organisms in Japanese coastal areas. Chattonella spp. (C. antiqua, C. marina
and C. ovata) have a cyst stage in their life cycle (Imai and Itoh 1987, 1988, Yamaguchi et al.
2008 on C. ovata). Empty cysts of Chattonella spp. can be commonly observed by the primulinstaining method (Yamaguchi et al. 1995) from deeper sediments from 1950 or before (Montani
2000). This is before the eutrophication period, or the high-growth period of the Japanese
economy. Therefore, Chattonella spp. are considered to be originally "hidden flora" (Smayda 2002),
which have usually lived at low cell densities since ancient times. Further, these species would
tend to form red tides after the eutrophication period. The warning level is 100 cells ml - 1 foraquaculture (Hiroshima Prefecture 1996).
Table 2-6 First occurrences of red tides and notes on the origin of therepresentative red-tide organisms in the Japanese coastal sea
Species

First red tide (year)

Notes

Warning level(cells ml- 1)

Chattonella antiqua

Hiroshima Bay (1969)

Hidden flora ＊100

Karenia mikimotoi

Ago Bay, Gokasho Bay
Mie Prefecture (1933)
Tokuyama Bay ,Yamaguchi Prefecture(1957)

Inherent red-tide
species

5,000

Heterosigma
akashiwo

Bingo- Nada , Okayama
Prefecture(1966)

Hidden flora ＊50,000

Heterocapsa
circularisquama

Uranouchi Inlet, Kochi
Prefecture (1988 )Introduced species

500

Cochlodinium
polykrikoides

Yatsushiro Bay, Kyushu(1975)

Hidden flora and/ortransported species by
Tsushima Current

500＊Thesespecies lived at low cell densities before the occurrence of red tide (Smayda 2002).

Heterosigma akashiwo is a cosmopolitan species in coastal areas of temperate andsubtropical countries (Honjo 1992, Smayda 1998). It also has a cyst stage in its life cycle (Imaiet al. 1993b, Imai & Itakura 1999); hence, H. akashiwo also appears to be originally a "hidden
flora" species. In the case of Karenia mikimotoi, the first report of red tide occurred in Gokasho
Bay in Mie Prefecture, a Pacific coastal embayment, in 1933, and in Tokuyama Bay, in the Seto
Inland Sea, in 1957. Since K. mikimotoi had caused noxious red tides recurrently before theperiod of eutrophication, this organism is considered to be an inherent red-tide species fromthe old days. The warning level is 5000 cells ml - 1 for aquaculture.
The first red tide of the bivalve-killer dinoflagellate H. circularisquama was recorded in
Uranouchi-Inlet, Kochi Prefecture, Shikoku, in 1988, and then in Fukuoka Bay, Kyushu, in 1989,
and in Ago Bay, Mie Prefecture, in 1992 (Tamai 1999). These three embayments are not locatedin the Seto Inland Sea. No overwintering resistant cysts have been identified so far. For thisdinoflagellate, winter temperatures of less than 15℃ in the Seto Inland Sea and most of theJapanese coastal seas are too low to overwinter (Yamaguchi et al. 1997). However, Shiraishi etal. (in press) recently discovered that H. circularisquama is overwintering as motile vegetative
cells in Uranouchi-Inlet. This species forms a temporary cyst, and it can be transferred
accompanied by commercially useful bivalves (Honjo et al. 1998). Recently, old samples of red
tides by H. circularisquama in Hong Kong in 1986 and 1987 were confirmed by Iwataki et al.
(2002). Accordingly, this species was originally considered to inhabit tropical coastal areas, andto have been introduced into Japanese coastal seas by warm currents and/or by the artificialtransportation of pearl oysters and short-necked clams for aquaculture (Matsuyama 1999). The
warning level is 500 cells ml - 1.

− 52 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

The dinoflagellate C. polykrikoides was reported to form the first red tide to kill fish in
the Yatsushiro Bay, Kumamoto and Kagoshima Prefectures, western Kyushu, in the summerof 1975 (Kumamoto Prefecture 1980). This species prefers high temperature and salinity for
optimum growth; however, this alga exhibited some growth even at a temperature of 10 ℃
(Yamatogi et al. 2005). The lowest water temperature is usually above 10 ℃ in the coastal areasof the southern and western parts of Japan. Consequently, C. polykrikoides might be able tooverwinter in those coastal areas, implying that this dinoflagellate was a "hidden flora" andbegan to cause red tides and kill cultured fish in 1975. Matsuoka & Iwataki (2004) pointed out
the two types of patterns of red-tide formation of this microalgae one is the Tsushima currentintroducing pattern in areas of western Kyushu and the coast of the Sea of Japan, and the otheris the independent-occurrence pattern in the Seto Inland Sea and Pacific coasts of Kyushu,
Shikoku and Honshu. The warning level of this species is 500 cells ml - 1.
2.4.4 Toxic blooms
Figure 2-41 shows representative microalgae causing toxic blooms (see Table 2-5) inthe coastal seas of Japan. Among the shellfish poisonings presented in Table 2-5, paralytic shellfish
poisoning (PSP) and diarrhetic shellfish poisoning (DSP) have actually occurred in Japanese
coastal waters (Fukuyo et al. 2002). DSP toxin contamination of marine shellfish such as scallops
and oysters has commonly been detected along the coast of the Hokkaido and Tohoku districts.
However, DSP toxin contamination has rarely been observed in the coast of western Japandespite the abundant existence of causative dinoflagellates of Dinophysis species such as D. fortii
Pavillard and D. acuminata Claparedèet Lachmann (Imai et al. 2003). This is an enigma to besolved in the future.

Figure 2-41 Toxic microalgae in the coastal seas of Japan
The pennate diatom Pseudo-nitzschia sp. for amnesic shellfish poisoning (ASP) (A), epiphytic dinoflagellate Prorrocentrum
lima for diarrhetic shellfish poisoning (DSP) (B), Dinophysis fortii for DSP (C), Dinophysis acuminata for DSP (D), chainforming dinoflagellate Alexandrium catenella for paralytic shellfish poisoning (PSP) (E) and Gymnodinium catenatum for PSP.
Scale bar, 20.

− 53 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
In the Seto Inland Sea, PSP contamination in bivalves was occasionally reported, mainly
in short-necked clam, in the 1970s and 1980s. The main causative organism was Alexandrium
catenella (Whedon et Kofoid) Balech (Dinophyceae) (Figure 2-36, E). However, in the 1990s andthereafter, toxic algal blooms and contamination of PSP toxins of bivalves have markedly
increased in frequency and scale in the Seto Inland Sea and coastal areas of Kyushu andShikoku of western Japan (Fukuyo et al. 2002, Kotani et al. 2004, Imai et al. 2006). The majorcausative organisms are Alexandrium tamarense (Lebour) Balech, A. catenella and Gymnodinium
catenatum Graham (Dinophyceae). Alexandrium cysts play an important role as a source of seedpopulations in the occurrences of toxic blooms (Anderson 1998, Itakura and Yamaguchi 2001).
The Alexandrium (A. tamarense and A. catenella) cysts were confirmed to be common and abundantin bottom sediments of the Seto Inland Sea and coastal areas of Kyushu and Shikoku (Yamaguchi
et al. 1996, 2002, Kotani et al. 1998). Therefore, toxic populations of Alexandrium spp. currently
appear to have become established in the Seto Inland Sea.
The origin of A. tamarense in the Seto Inland Sea after the 1990s is unknown at present,
but it is suspected that the introduction of bivalves from the northern part of Japan (A. tamarense
is common) was accompanied with cysts of A. tamarense (Furuhata et al. 1996) in the Seto Inland
Sea. Actually, oysters have often been transferred to the Seto Inland Sea from the Tohoku
district. Human activities can thus cause eutrophication of coastal waters and also help expansionof the distribution of harmful algal species to unaffected areas. More careful monitoring is neededin coastal environments of the Seto Inland Sea.

− 54 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

2.5 MARINE POLLUTION FROM OIL SPILLS AND OTHER CAUSES
2.5.1 Oil pollution
Crude oil and petroleum products are usually carried by marine transportation systems,
and hence oil tanks, oil refineries and petrochemical industrial complexes have predominantly
been constructed in coastal areas. Therefore, accidents involving oil tankers on the sea and oil
tanks on land inevitably cause marine pollution through oil spills. The most notorious and serious
case in Japan was the "Mizushima Heavy-Oil Leakage Accident", which occurred at Mizushima
Oil Refinery in Kurashiki City, Okayama Prefecture, on 18 December, 1974 with its accompanying
oil spill of 42,888 kl (Okaichi and Tatsumi 1975). A lot of marine wildlife such as birds, fish,
invertebrates and seaweed in the Seto Inland Sea were killed and affected by pollution, including
aquaculture organisms, and the total amount of damage was estimated to be about 53.6 billion
Japanese yen, which included compensation for fisheries damage. The accident involving theRussian Tanker "Nakhodka" occurred off Oki Island on 2 January, 1997 with an oil spill of 6,
240 kl, which affected the coasts of prefectures facing the Sea of Japan (Maruyama 2005,
Komatsu et al. 2005). In this case, large numbers of volunteers gathered together to collect theoil on the coast (Ishii 1998). The world's largest oil spill occurred in the Persian Gulf during
the Gulf War from 17 January to 3 March, 1991, with a total spillage of 0.95 to 1.27 million kl,
which killed a huge amount of marine wildlife (Okaichi 1997).
There are many petroleum-related facilities and oil tankers navigating the Seto Inland
Sea. Figure 2-42 shows changes in the number of oil spills confirmed in the Seto Inland Sea(Association for the Environmental Conservation of the Seto Inland Sea 2006). In 1970, the total
number of incidents over the whole country was 349, while that of the Seto Inland Sea alone
was 155. The number of incidents then rapidly increased to a maximum of 2,060 over thewhole country in 1973, with 874 in the Seto Inland Sea in 1972. However, marine pollution spillages
from oil thereafter gradually decreased to 271 over the whole country and to 57 in the Seto
Inland Sea, respectively, in 2004. These decreases were attributable to the contribution ofcountermeasures such as the regulation and the enforcement of monitoring systems, and theconstruction of waste oil treatment facilities, etc, which have been implemented based on the "Law Relating to the Prevention of Marine Pollution and Maritime Disasters" (International
EMECS Center 1999).
Number of Oil Pollution
2,500
All over Japan
Seto Inland Sea
2,000

1,500

1,000

500

0

1970

1980

1990

2000

2005 Year

Note: Source; The Association for the Environmental Conservation of the Seto Inland Sea 2006.

Figure 2-42 Occurrences of oil spills over the whole of Japan and the Seto Inland Sea from 1970
to 2005− 55 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
Spatial distribution of oil pollution in 2004 is depicted in Figure 2-43 (Setouchi Net, HP).
The areas of oil pollution tended to be found around the oil and chemical industrial complexes,
but were also found in the sea areas. Since the Seto Inland Sea is an enclosed sea with large
populations of marine life, beautiful scenery, abundant fisheries and aquaculture, oil spills
would result in serious damage to the fishing and tourism industries, which was clearly
demonstrated by the "Mizushima Heavy-Oil Leakage Accident". Careful monitoring is essential
for conserving the Seto Inland Sea from oil pollution.

Hyogo Pref.

Okayama Pref.

Harima-nada

Hiroshima Pref.

Osaka
bay

Osaka
Pref.
Nara
Pref.

Bingo-nada

Kagawa Pref.

Hiroshima bay

Yamaguchi Pref.

Hiuchi-nada

Tokushima Pref.

Wakayama
Pref.

Suo-nada
Iyo-nada

FukuokaPref.

Ehime Pref.

Oita Pref.

0

10

20

30 km

Hyogo Pref.

Osaka bay

Osaka Pref.

Wakayama Pref.
Note: Source; Setouchi Net, HP

Figure 2-43 Distribution of oil spills in the Seto Inland Sea in 2004

− 56 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

2.5.2 Chemical pollution by dioxins
Dioxins are one of the most typical chemical pollutants with high toxicity in the sea.
According to the definition given by the World Health Organization (WHO), dioxins arecomposed of PCDD (Polychlorinated Dibenzo-para-Dioxin), PCDF (Polychlorinated Dibenzo Furan)and Co-PCB (Coplaner Polychlorinated Biphenyl). In human and other vertebrates, dioxins havebeen shown to be risk factors in causing cancers, immune deficiency disorders, reproductive
and developmental abnormalities, central and peripheral nervous system pathologies, endocrine
disruption, decreased pulmonary functions and bronchitis, altered serum testosterone levels,
eyelid pathologies, gum pigmentations, nausea, vomiting, loss of appetite, skin rashes, hypertrichosis,
liver damage, etc (Schecter et al. 2006). The main sources for marine dioxin pollution are from
impurities contained in herbicides such as PCP (Pentachlorophenol) and CNP (Chlornitrofen),
which were used abundantly in the past (currently banned) in agriculture and flowed into thesea (Kawai and Yamamoto 2004). Since dioxins are persistent organic pollutants and accumulate
in fatty tissues, these are eventually transferred to humans in food (fish and bivalves) via thefood chain through biological concentrations in marine ecosystems.
Dioxins are also produced unintentionally by the burning of many materials containing
chlorine compounds, for example, municipal and domestic waste incineration. In this context,
the Teshima Affair highlighted the seriousness of the dioxin problem. Teshima Island belongs
to Kagawa Prefecture and is located in the Seto Inland Sea National Park. Industrial and businesswastes were carried into this island and treated by open incineration by an unscrupulous dealer for more than ten years, leading to the production of heavily dioxin-polluted matters of morethan 500 thousand tons. Dioxin-polluted leakage flowed into the surrounding sea and polluted
the coastal environment, which was demonstrated by the accumulation of high-level dioxins innatural oysters around the coast of the island. It was estimated that it would need around 20
billion yen and more than ten years for the dioxins to be eliminated from these areas.
The Environment Agency of Japan surveyed the concentrations of dioxins in sea regions
such as Tokyo Bay, Ise Bay (Mie and Aichi Prefectures), the Seto Inland Sea, etc, in March
1996, and presented the results in May 1996, as shown in Table 2-7. The concentration levels
were 0〜0.0003 ng TEQ L - 1, where TEQ refers to "toxicity equivalent quantity". In the isomer
pattern of dioxins, OCDD was detected in all the samples examined, and then 1,2,3,7,8-PeCDF
was detected in 58% of the samples. The ratios of other dioxins were 0〜17% in the samples
determined. In 1999, the Law concerning Special Measures against Dioxins was enacted andstandards were determined for a tolerable daily intake (TDI, 4 pg kg - 1 per day), environmental
quality (atmosphere, water, sediment and soil) and emission control. Dioxin content was measured
for the water samples collected from 133 different locations in the Seto Inland Sea in 2004, andthe values were lower than the environmental quality standards for dioxins of 1 pg-TEQ L - 1
by virtue of the implementation of various controls based on the law. The average dioxin intakeof the average Japanese person in 2005 was 1.20 pg-TEQ kg - 1 per day from total food intake,and 1.09 pg-TEQ kg - 1 per day from seafood, indicating about 90% of the daily total food intake
via seafood (Fisheries Agency 2006). Although the total intake of dioxins was sufficiently lower
than the standard TDI (4 pg kg - 1 per day), Japanese people take most of their dioxins (> 90%) via seafood. We should be careful concerning our dietary intake, keeping a good balancewith regard to seafood, e.g. we should avoid eating a large amount of the fatty part of oily fish.

− 57 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
Table 2-7 Average concentrations of dioxins in seas (fiscal year: 1995)
Chemicals
2,3,7,8 - TeCDD
1,3,6,8 - TeCDD
1,3,7,9 - TeCDD
other - TeCDD
1,2,3,7,8 - PeCDD
other - PeCDD
1,2,3,4,7,8 - HxCDD
1,2,3,6,7,8 - HxCDD
1,2,3,7,8,9 - HxCDD
other - HxCDD
1,2,3,4,6,7,8 - HpCDD
other - HpCDD
OCDD
1,3,6,8 - TeCDF
PCDFs
2,3,7,8 - TeCDF
other - TeCDF
1,2,3,7,8 - PeCDF
2,3,4,7,8 - PeCDF
other - PeCDF
1,2,3,4,7,8 - HxCDF
1,2,3,6,7,8 - HxCDF
1,2,3,7,8,9 - HxCDF
2,3,4,6,7,8 - HxCDF
other - HxCDF
1,2,3,4,6,7,8 - HpCDF
1,2,3,4,7,8,9 - HpCDF
other - HpCDF
OCDF
PCDDs + PCDFs
TOTAL TEQ NATO(ngTEQL - 1)
PCDDs

(dimension; ngL- 1)

Tokyo BayIse Bay

Seto Inland Sea

Total

N.D.
0.003
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
0.002
0.002
0.036
N.D.
N.D.
N.D.
0.002
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
0.002
0.004
0.051
0.0001

N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
0.007
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
0.007
0.0000

N.D.
N.D.
N.D
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
0.006
N.D.
N.D.
N.D.
0.002
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
0.008
0.0000

N.D.
0.001
N.D.
N.D
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
0.001
N.D.
0.016
N.D.
N.D.
N.D.
0.001
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
0.001
0.020
0.0001

Note: N.D. means "not detectable". Detected limit is 0.001 ngL - 1

2.5.3 Endocrine disruptors
The endocrine system plays an important role in growth, metabolic regulation, immunity
and reproduction in humans and animals. Hormones of the steroid-type (sex hormones) arebasically essential for reproduction. Therefore, disruptions in the activity of sex hormones affectreproduction rather than vital activity of individuals, leading to unsuccessful reproduction andhence to the extinction of populations of species.
The phenomenon of endocrine disruptions has been observed in various aquatic animals.
For example, populations of seals in the Baltic Sea have drastically decreased since the 1960s.
Infertile females showed a tendency with higher levels of DDT (dichlorodiphenyltrichloroethane)
and/or PCBs (polychlorinated biphenyls) in their tissues. Male fish inhabiting areas downstream
from the discharge of a sewage-treatment plant often produce vitellogenin (VTG), which isimportant for producing the protein of egg yolk, indicating the effects of estrogen-like substancesin water.
In marine invertebrates, especially gastropods, imposex (the superimposition of the malesex organ on female sea snails) was observed on various coasts around the world along withan increase in the quantity of TBT (tributyltin) and TPT (triphenyltin) used as antifouling paints
for ship hulls and fishing nets. It was reported that imposex was observed in more than 140
species of gastropods along the world's coasts in 1998 (Horiguchi 2000), and 39 of 69 species
examined were affected by imposex along the Japanese coast in the 1990s (Horiguchi et al. 1997,
Horiguchi 2000). Imposex of the sea snail Thais clavigera was observed from the samples of− 58 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

almost all the investigated points. Furthermore, laboratory experiments for T. clavigera demonstrated
a significant positive relationship between the concentration of organotin compounds (TBT +TPT) in body tissues and the RPL (relative penis length) index indicating the degree of imposexof female snails. Thais clavigera decreased in the early 1990s along with an increase of organotin
pollution along the coasts of Japan, including the Seto Inland Sea (Horiguchi 2000). It is also
suspected that the decrease in the size of the catch of abalone along Japanese coasts is due tothe inhibition of reproduction by imposex (Horiguchi 2000). Organotin compounds are also
biologically accumulated in fish (Yamada 1999), and were actually detected from the tissues ofseabass (Lateolabrax japonicus) with values as high as 2.6 裹 g - 1 of TPT in 1989, and from finless
porpoise (Neophocaena phocaenoides) as high as 460 ng g - 1 fat in 1996, both from the Seto Inland
Sea.
Because of their toxicity, TBT and TPT were designated as specified chemical substancesin 1990, and the banning of the use of organotin compounds as antifouling paints for fishingnets and ship hulls was announced by the Associate Director-General of the Fisheries Agency
in July 1991. Concentrations of organotin compounds in seabass decreased to as low as around0.1裹 g - 1 after the regulation came into effect in the Seto Inland Sea. As for the international
regulation of harmful organotin compounds, the "International Convention on the control ofharmful Anti-fouling Systems on Ships" (AFS) was adopted at the meeting of International
Maritime Organisation, with Japan taking a leading role, on 5 October 2001. The substance of
the AFS treaty was that the use of organotin compounds was banned from January 1, 2003,
and the use of organotin compounds was not permitted on ship hulls. This treaty needed ratification
by 25 countries to come into force. Panama became the 25th country to ratify it on September
17, 2007, and the AFS will actually become effective on September 17, 2008. Future problems
include ensuring adherence to the ASF, methods for checking, operation, and the developmentof alternatives to organotin compounds. It is hoped that the AFS will play a major role in solving
the problems of organotin compounds in the near future.
2.5.4 Marine debris
Marine debris has become a big issue environmentally along shorelines, and in coastal
waters, estuaries, and oceans throughout the world, based on mass production, mass consumption
and mass dumping by the economies of the world. Marine debris is man-made solid material
that is carried into the sea from land and ocean sources either directly by dumping or indirectly
through river flows or drainage. There are various types of marine debris, such as plastics(bags, cups, bottles, strapping bands, plastic sheeting, resin pellets), styrofoam, rubber, glass,metal, derelict fishing gear (nets, lines, crab/shrimp pots, piping, floats, paints and adhesives),
derelict vessels, etc (NOAA Marine Debris Program, HP). Marine debris goes to and arrives
from other countries by riding sea currents, e.g. from China and Korea to Japan, and fromJapan to Hawaii, USA.
Harmful marine debris causing injury and mortality to marine life by entanglement
and ingestion consists of plastic garbage, fishing gear abandoned by professional and visiting
fishermen, and non-degradable floating materials. Entanglement in fishing lines and fragmentsof nets or plastic materials can cause drowning, amputation, restricted mobility and starvation
to turtles, whales, sharks and sea birds (petrels and albatrosses). Many marine animals confuse
plastic bags, wrappers, etc. with prey and eat them, leading to blockage in the gastrointestinal
system. For example, turtles often ingest plastic bags when they confuse them with theircommon prey of jellyfish. When plastic sheeting covers immobile organisms such as corals, they
are smothered and sometimes die.
Marine debris will have negative effects on human activity in the sea, e.g. with fisheries.
The garbage of marine debris becomes mixed in with the catch, and more sorting is neededin the process. Fishing nets are sometimes broken by heavy marine debris made of metal.
The problem of marine debris that fisheries face is more serious in good fishing grounds suchas the Seto Inland Sea.

− 59 −

Chapter2 CHANGES IN THE ENVIRONMENT OF THE SETO INLAND SEA
Marine debris also creates a negative impact on marine tourism by damaging scenery,such as when garbage is abundant along the coast. Marine leisure and sports are also affectedby marine debris, for example when driftwood causes boating accidents. The cost of clearing
these obstacles is substantial.
The Ocean Conservancy, an American NGO, established the annual International Coastal
Cleanup (ICC) with support from the U.S. Environmental Protection Agency (U.S. EPA) and otherstakeholders (U.S. EPA: http://www.epa.gov/owow/oceans/debris/). The first cleanup was in
Texas in 1986, and the campaign currently involves all of the USA and more than 100 countries
around the world. A NGO (JEAN: Japan Environmental Action Network) was established in1990 corresponding to the campaign by the ICC, and the JEAN works on coastal cleanups,
gathering data on marine debris, making reports and other related works (Kojima 2005). Actually,
the cleanup of marine debris along the coasts currently is substantially dependent on the dedicationand labor of volunteers organized by NGOs such as JEAN (Kurashige 2004).
In the Seto Inland Sea, marine debris on the sea bottom was investigated in the BisanSeto area by the Mizushima foundation (Shiwaku 2005). The major part of the debris consistedof plastic materials (86% in number, 50% in weight), followed by cans and fishing gear. Dataobtained from cans revealed that garbage has continually been thrown into the sea. Administrative
systems have temporarily dealt with countermeasures to marine debris, although there is nolong term ongoing commitment. This is due to a lack of a distinct policy by the administrative
authorities to take responsibility for the treatment of marine debris collected from the sea.
The preparation of legislative measures and financial resources would basically be essential forthe establishment of an effective system for treating the marine debris collected. And further,close and proper partnerships are important among ordinary people, fishermen, civil corporations
and public administrations for aiming at the solution of the problems of marine debris.

− 60 −

Chapter 3 MEASURES FOR THE CONSERVATION OF THE
ENVIRONMENT OF THE SETO INLAND SEA
3.1

MEASURES FOR THE CONSERVATION OF ENCLOSED COASTAL SEAS

62

3.2 MEASURES AND STRATEGIES BASED ON THE SPECIAL LAW
FOR THE CONSERVATION OF THE ENVIRONMENT OF THE
SETO INLAND SEA

64

3.3 PROMOTION OF PREFECTURAL PLANS FOR CONSERVATION
OF THE SETO INLAND SEA

66

3.4 PERMISSION FOR THE INSTALLATION OF SPECIFIED FACILITIES

66

3.5 TRANSITION OF THE TOTAL AMOUNT OF POLLUTANTS LOADED66

3.6 POLLUTANT LOADS AND THEIR CONCENTRATION IN SURFACEWATER IN THE SETO INLAND SEA

68

3.7 DESIGNATION OF NATURAL SEASHORE CONSERVATION AREAS

72

3.8 REGIONAL ENVIRONMENTAL POLLUTION CONTROL PROGRAM

73

3.9 CONSTRUCTION AND IMPROVEMENT OF SEWERAGE AND
OTHER SYSTEMS

73

3.10 CONSTRUCTION OF SOLID WASTE TREATMENT AND
OTHER FACILITIES

75

3.11 CONSTRUCTION OF WASTE OIL TREATMENT AND
OTHER FACILITIES

76

3.12 RESTRICTIONS BASED ON THE SPECIAL LAW FOR THE
CONSERVATION OF THE ENVIRONMENT OF THE
SETO INLAND SEA

76− 61 −

Chapter3 MEASURES FOR THE CONSERVATION OF THE ENVIRONMENT OF THE SETO INLAND SEA
3.MEASURES FOR THE CONSERVATION OF THE ENVIRONMENT OF
THE SETO INLAND SEA
3.1 MEASURES FOR THE CONSERVATION OF ENCLOSED COASTAL SEAS
As mentioned in Chapter 2, during the period of high economic growth after WorldWar II, the enclosed seas of Japan were heavily eutrophicated because large quantities ofindustrial effluent, as well as domestic sewage, were released into the sea. For the Seto Inland
Sea in particular, the Environmental Agency enacted the Special Law for the Conservation of
the Environment of the Seto Inland Sea in 1973, which aimed to improve water quality, andefforts to improve water quality have continued ever since the law was enacted. Measures
introduced for the conservation of the enclosed coastal seas in Japan were as follows.
(1) Control of Total Loading of Organic Substances (COD)
1) The total pollutant load control system was established with the amendment of the Water
Pollution Control Law in 1978. The objective of this system was the degree of reduction in
the total amount of pollutant load that would be required to clear the water quality standard
in the designated seas, which had a polluted watershed from the high concentration of
population and industry. Three enclosed coastal seas, Tokyo Bay, Ise Bay and the Seto
Inland Sea were designated under the system. The indicator for pollutants was COD.
2) Different measures for reducing pollutant loading from households, industry and othersources of pollutants were comprehensively implemented after the enforcement of the total
pollutant load control system in 1979. The 5th control enforcement of total pollutant loadwith a target fiscal year of 2004 was subsequently implemented. At present, the 6th control
enforcement of total pollutant load with a target fiscal year of 2009 has begun. These arebased on both the Fundamental Policy for Reduction of Area-Wide Total Pollutant Loadestablished by the Prime Minister in April, 1996 and the Plan For Reduction of Total Pollutant
Load established by each Governor of the prefectures concerned in June, 1996.
3) The local governments concerned have been steadily promoting this enforcement to achieve
the plan's target. They also intend to implement an "investigation on the management ofpollutant load" and a "wide area survey on water quality".
(2) Promotion of Comprehensive Measures for Conservation of Water Quality
1) Enclosed coastal seas such as Tokyo Bay, Ise Bay and the Seto Inland Sea have sufferedfrom the problems of eutrophication. In order to reduce the load of nitrogen and phosphorus,
different types of enforcement have been steadily implemented under the establishment ofenvironmental standards, the application of each of its categories to each sea district, therestriction of effluent concentration, and so on.
2) The degree of achievement in environmental COD standards has been low in these enclosed
seas. Also, these seas are suffering from several problems caused by eutrophication suchas red tide and the formation of oxygen-deficient water. Under these conditions, the Special
Committee on Control of Total Pollutant load in the Section of Water Quality of the Central
Environment Conservation Council reported that it is important to reduce not only COD
but also nitrogen and phosphorus in order to improve water quality in enclosed coastal
seas. Further, the Special Committee has also required the promotion of comprehensive
measures for water quality.
3) In the 5th control enforcement, which started from 2000, the relevant ministries and agencies
and local governments were required to cooperate with each other to reduce not only the
COD concentration produced by nitrogen and phosphorus but also the concentration ofexogenous COD, and to prevent the problems of eutrophication such as red tide and thedepletion of dissolved oxygen.
4) In the 6th control enforcement, which started from 2007 with a target fiscal year of 2009,it was considered that the present water quality should be maintained in the Seto InlandSea, excluding Osaka Bay, although nitrogen and phosphorous loading should be continually
reduced in Osaka Bay.
The above statements are summarized in Table 3.1.

− 62 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Table 3-1 Development of Comprehensive Measures for Water Quality
Conservation in the Seto Inland Sea
COD
October 1973

March 1980

April 1987

March 1991

Eutrophication

The Interim Law for Conservationof the Environment of the
Seto Inland Sea was enacted.
(Target: to reduce by half the
COD Load for industrial waste
water in 1972 within 3 years)

July 1979

First control of total load of COD(Base fiscal year: 1979, Target fiscal December 1985
year: 1984)

Second control of total load of COD(Base fiscal year: 1984, Target
fiscal year: 1989)
December 1990
Third control of total load of COD(Base fiscal year: 1989, Target fiscal
year: 1994)
August 1993
October 1993
February 1995

August 1995

September 1996

"Basic Policy for the fourth control
of total load of COD" (Report from March 1996
the Professional Meeting on Controlof Total Load, Water Quality
Sectional Meeting in the National
Council for the Environment)
June 1996
Fourth control of total load of COD(Base fiscal year; 1994. Target
fiscal year; 1999)
April 1997

July 1997

October 1997
February 2002

July 2002

October 2006

"Basic Policy for the fifth control of
total load of COD" (Reportfrom the Professional Meeting onControl of Total Load, Water
Quality Sectional Meeting in the
National Council for theEnvironment)
The fifth control of total load of
COD, Nitrogen and Phosphorous(Base fiscal year; 1999. Target fiscal
year; 2004)"Basic Policy for the sixth control
of total load of COD" (Report fromthe Professional Meeting on Controlof Total Load, Water Quality
Sectional Meeting in the National
Council for the Environment)− 63 −

Instruction on preparation of thefirst phosphorus and nitrogenloading reduction guideline (Basefiscal year: 1979, Target fiscal year:
1984)
Instruction on preparation of thesecond phosphorus and nitrogenloading reduction guideline (Basefiscal year: 1984, Target fiscal year:
1989)
Instruction on preparation of thethird phosphorus and nitrogenloading reduction guideline (Basefiscal year: 1989, Target fiscal year:
1994)
Nitrogen and phosphorus control
standards relating to sea
established.
Nitrogen and phosphorus control
standards relating to enclosed
coastal seas enacted.
Application of classes of N & P
Environmental Standard for Osaka
Bay
Instruction on preparation of the
fourth phosphorus andnitrogen-loading reduction guide-line(Base fiscal year; 1994.
Target fiscal year; 1999)
Application of classes of N & P
Environmental Standard for Harimasea area, western and southern sea
areas of Awaji island
Application of classes of N & P
Environmental Standard tonorth-west part of Harima
Open Sea, Bisanseto Strait, east,
north-west and central westernparts of Hiuchi Open Sea, Iyo
Open Sea, Uwa Sea, north, west
and southern parts of Hiroshima
Bay, the sea area facing Kure City,sea area facing Akitsu-Ysuura,
Hibiki Open Sea, and Subou OpenSea
Application of classes of N & P
Environmental Standard for the sea
area of Tousan, and the easternpart of Kii Channel
Application of classes of N & P
Environmental Standard for the sea
areas of Yanai-Oshima
Hirao-Kaminoseki, Sasato Bay-Hikari,
Tokuyama Bay, Mitajiri Bay-Bouhu,
Nakanoseki-Ooumi,
Yamaguchi-Akiho, and ToyouraToyokitaChapter3 MEASURES FOR THE CONSERVATION OF THE ENVIRONMENT OF THE SETO INLAND SEA
3.2 MEASURES AND STRATEGIES BASED ON THE SPECIAL LAW FOR THE
CONSERVATION OF THE ENVIRONMENT OF THE SETO INLAND SEA
Various measures for the conservation of the environment of the Seto Inland Sea havebeen implemented based on the Law Concerning Special Measures For Conservation of The
Environment of The Seto Inland Sea and the Basic Plan For Conservation of The Environmentof The Seto Inland Sea, as outlined below.
3.2.1 Outline of the Special Law for the Conservation of the Environment of the Seto
Inland Sea
Tentative Law (established October 2, 1973, enforced November 11, 1973)
Permanent Law (established; June 13, 1978, enforced June 12, 1979)
1. Plans for the Conservation of the Environment of the Seto Inland Sea (Articles 3 and 4*)
National Basic Plan (Established: April, 1978, Published: May, 1978, Amended: July in 1994)
Prefectural Plan (Established: July, 1981, Amended: December, 1987, June, 1992 and September,
1997)
2. Permission for the Installation of Specified Facilities (Articles 5 to 10*)Those who grant permission: Governors of prefectures or designated cities
Specified Facilities: Industries and Places of Business discharging wastewater in excess of
50 m3/dayPre-assessment of environmental impact resulting from the operation of the facilities are
required.
3. Reduction of Total Amount of Pollution Load (Article 12-3*)
Designated Pollutant; COD (First control plan: June, 1979. Second control plan: January, 1987.
Third control plan: January, 1991. Fourth control plan; April, 1996. Fifth control plan; December,
2001, Sixth control plan: November, 2006)
4. Guidelines for Reduction of Specified Substances (Article 12-4*)
Specified Substances

Instruction by Minister of E.A.

Enactment by
Prefectural Governor

First Plan

Phosphorus

June, 1979

April - May, 1980

Second Plan

Phosphorus

December, 1985

April - May, 1986

Third Plan

Phosphorus

December, 1990

April - May , 1991

Fourth Plan

Nitrogen & phosphorus

March, 1996

June - July, 1996

Fifth Plan

Nitrogen & phosphorus

July, 2002―

Sixth Plan

Nitrogen & phosphorus

October, 2006―

5. Countermeasures for Natural Seashore Conservation (Articles 12-7, 8*)
Designation of Natural Seashore Conservation Area
The prefectures concerned designate the area by ordinance. The 91 areas were designatedat the end of December, 1997.
6. Special Consideration Given to Reclamation (Article 13*)
In considering the license for reclamation taken in the Seto Inland Sea, the governor of
the prefecture concerned should take into account the peculiarities of the Seto Inland Sea.
The basic policy for reclamation proposed by the Seto Inland Sea Conservation Council inMay, 1974, should be applied.
7. Other
1) Promotion of improvement in and construction of seawage systems and solid waste treatment
facilities
2) Prevention of oil spills from accidents
3) Promotion of the development of technologies for Environmental Conservation
4) Relief for fishermen adversely affected by red tides
Note: Prefectures concerned with the Seto Inland Sea (13 Prefectures) Kyoto, Osaka, Hyogo,
Nara, Wakayama, Okayama, Hiroshima, Yamaguchi, Tokushima, Kagawa, Ehime, Fukuoka,
Ooita− 64 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

3.2.2 Outline of the Basic Plan for the Conservation of the Environment of the Seto
Inland Sea
Nature of the Plan This plan clearly points out the basic direction of measures whichshould be adopted in order to indicate objectives for the conservationof the environment of the Seto Inland Sea, so that these objectives
may be achieved by the national government, regional governments,and others. And, in addition to being reflected in the various plansregarding the conservation of the environment of the Seto InlandSea, this plan should act as a guideline in the enforcement of various
related measures.
1. Objectives of the Plan
1) Objectives Regarding Water Quality Maintenance
These objectives are concerned with the achievement and maintenance of theenvironmental quality standards for water quality, classifying the mechanism of theoccurrence of red tide, the removal of toxic sediment as well as the prevention of
its adverse effects, the conservation of seaweed beds and tidelands, and the conservationof the natural seashore.
2) Objectives Regarding the Conservation of Natural Beauty
These objectives are concerned with the conservation of the main areas of natural
beauty (including national parks, prefectural natural parks), the protection and maintenanceof greenery, the conservation of the natural seashore, the maintenance of a cleansea surface as well as seashore, and the conservation of such cultural properties ashistoric relics, scenic spots and natural monuments.
2. Basic measures for achieving these objectives
1) Water pollution prevention
These include measures for the enforcement of area-wide total water pollutant
load control, the prevention of the occurrence of damage caused by eutrophication(including the reduction of the pollution load of phosphorus), the prevention of oil
pollution, and other measures2) Conservation of natural beauty
This includes the conservation of natural park and other areas, the conservationof areas with a lot of greenery, the conservation of historic relics, scenic spots andnatural monuments, the removal of garbage, oil and other such pollutants, and othermeasures (including the conservation of the natural beauty of the coastline).
3) Conservation of the seaweed beds and tidelands
4) Conservation of the natural seashore (conservation of areas designated as natural
seashore reserves)5) Consideration of environmental conservation regarding reclamation (in accordancewith the Basic Policy for Reclamation)6) Improvement of sewerage and other systems7) Improvement of waste treatment facilities, and securing locations for waste treatment
8) Removal of sludge from the ocean floor and river bottoms
9) Monitoring and surveying water quality
10) Research and investigation on environmental conservation, and technological development
11) Spreading ideas related to environmental conservation, and raising the level ofawareness of the environment12) Measures for support by the National Government*: See : Appendix 6.5 THE SPECIAL LAW FOR THE CONSERVATION OF THE ENVIRONMENTOF THE SETO INLAND SEA− 65 −

Chapter3 MEASURES FOR THE CONSERVATION OF THE ENVIRONMENT OF THE SETO INLAND SEA
3.3 PROMOTION OF PREFECTURAL PLANS FOR CONSERVATION OF THE
SETO INLAND SEA
The governors of the 13 prefectures concerned drew up plans for each prefecture
including measures for the conservation of the environment of the Seto Inland Sea in July, 1981.
These were on the basis of the Basic Plan based on Article 4 in the Special Law for theConservation of the Environment of the Seto Inland Sea.
Some parts of the prefectural plan have been revised four times: December, 1987, June,
1992, September, 1997 and July, 2002, to correspond to changes in several plans included in
the prefectural plan.
*: See : Appendix 6.5 THE SPECIAL LAW FOR THE CONSERVATION OF THE ENVIRONMENTOF THE SETO INLAND SEA

3.4 PERMISSION FOR THE INSTALLATION OF SPECIFIED FACILITIESA system for granting permission for the installation of specified facilities was adopted
based on the regulations in Articles 5* and 8* of The Special Law for the Conservation of theEnvironment of the Seto Inland Sea. Installation of 296 facilities and modification of 540 facilities
were permitted in 2004.
*: See: Appendix 6.5 THE SPECIAL LAW FOR THE CONSERVATION OF THE ENVIRONMENTOF THE SETO INLAND SEA

3.5 TRANSITION OF THE TOTAL AMOUNT OF POLLUTANTS LOADEDThe total amount of COD loaded into the Seto Inland Sea has continued to decreasesince 1979 when the system for controlling the total amount was introduced on the basis of
the Law Concerning Special Measures for Conservation of The Environment of The Seto Inland
Sea.
Trends in the annual average COD at monitoring points for Environmental Standard,
trends in the total amount of COD loaded, and COD concentration in 18 nada and bays in the
Seto Inland Sea are shown in Figures 3-1, 3-2 and 3-3, respectively.
The total amount of phosphorus loaded has tended to decrease slowly since 1974 whenguidance for a reduction in phosphorus load was introduced. The trend for the total amountof phosphorus loaded is shown in Figure 3-4.
Total amount of nitrogen loaded tends to increase since 1984 as shown in Figure 3-5.
Accordingly, the guidance for reduction of total amount of nitrogen loaded has started in 1996.

COD average value (mg/L)
3.5
3.0
2.5
2.0
1.5
whole Seto Inland Sea
category A
category B
category C

1.0
0.5
0.0

1985

1990

1995

2000

2005 Fiscal Year

Note: Source; Ministry of the Environment of Japan

Figure 3-1 Changes in annual average COD at the Monitoring Points forEnvironmental Standards in the Seto Inland Sea− 66 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

COD loads (ton/day)2500
domestic + others
othersdomestic
industrial

2000
1500
1000
500
0
1961

1968

1972

1979

1984

1989

1994

1999

2004 Fiscal
Year

Note: Sources; Ministry of the Environment of Japan, and the Association for theEnvironmental Conservation of the Seto Inland Sea

Figure 3-2 Changes in Total Amount of COD Load in the Seto Inland Sea

COD value (mg/L)
3.5
3.0
2.5
2.0
1.5
1.0
0.5

average

Hibiki-nada

Bungo channel

Western Suo-nada

Eastern Suo-nadaWestern Iyo-nada

Eastern Iyo-nada

Hiroshima bay

Aki-nada

Hiuchi-nada

Bingo-nadaWestern Bisan-seto

Eastern Bisan-seto

Southern Harima-nadaNorthern Harima-nadaSouthern Osaka bay

Northern Osaka bay

Western Kii channel

Eastern Kii channel

0.0

Note: 1) Yearly mean concentration in each nada and bay
2) Source; Ministry of the Environment of Japan

Figure 3-3 COD Concentration in 2004 at 18 nada and bays in the Seto Inland Sea− 67 −

Chapter3 MEASURES FOR THE CONSERVATION OF THE ENVIRONMENT OF THE SETO INLAND SEA
Total Phosphorus loads (ton/day)70

othersdomestic
industrial

60
50
40
30
20
10
0
1979

1984

1989

1994

1999

2004 Fiscal
Year

Note: Source; Ministry of the Environment of Japan

Figure 3-4 Changes in the Total Amount of Phosphorus Load in the Seto Inland Sea
othersdomestic
industrial

Total Nitrogen loads (ton/day)
800
700
600
500
400
300
200
100
0
1979

1984

1989

1994

1999

2004 Fiscal
Year

Note: Source; Ministry of the Environmental of Japan

Figure 3-5 Changes in the Total Amount of Nitrogen Load in the Seto Inland Sea

3.6 POLLUTANT LOADS AND THEIR CONCENTRATION IN SURFACEWATER IN THE SETO INLAND SEA
The relationship between COD load and COD concentration of three of the largest
enclosed coastal seas in Japan - Tokyo Bay, Ise Bay and the Seto Inland Sea - is shown in
Figure 3-6. The COD loads in 1979 were 1,012 tons/day in the Seto Inland Sea, 477 tons/dayin Tokyo Bay and 307 tons/day in Ise Bay. Correlating to the decrease in pollutant load, agenerally proportional decrease in COD concentration was observed, although the levels of loadand concentration differ according to the specified area. It is noted that the level of Osaka
Bay in the Seto Inland Sea is very high compared with that in other areas of the Seto Inland
Sea. Also, loads and the relationship between nitrogen and phosphorus concentration are shownin Figure 3-7 and 3-8. The nitrogen loads thus estimated in 1979 amounted to 666 tons/day in
the Seto Inland Sea, 364 tons/day in Tokyo Bay and 188 tons/day in Ise Bay while those forphosphorus were 62.91 tons/day, 41.2 tons/day, and 24.4 tons/day, respectively. According to
the decrease in nitrogen and phosphorus load, relatively proportional decreases in nitrogen and− 68 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

phosphorus concentration were also observed, although the relationships between nitrogen andphosphorus differ slightly. Similar to COD, the levels of concentration of nitrogen and phosphorous
were very high compared with other areas of the Seto Inland Sea. As mentioned above, theseresults suggest that the quality of surface water depends on COD, nitrogen and phosphorus
load coming from the land (Matsuda).

'79-'83'84-'88'89-'93'94-'98'99-'03

Average COD (Upper Layer, mg/L)

5.0
Tokyo Bay
4.0
Osaka Bay

3.0
Ise Bay
2.0

Seto Inland Sea (excluding the Osaka Bay)
1.0

0.0
0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

COD Load per Unit Area of Water (ton/day/km2)
Note: Source; Ministry of the Environment of Japan (2005)

Figure 3-6 Relationship between COD load and average COD concentration in sea water'79-'83'84-'88'89-'93'94-'98

1.6'99-'03
Tokyo Bay

Average TN Concentration

1.4
1.2
1.0
Osaka Bay

0.8
0.6
Ise Bay

0.4

Seto Inland Sea (excluding the Osaka Bay)

0.2
0.0
0.00

0.05

0.10

0.15

0.20

0.25

0.30

Nitrogen Load per Unit Area of Water (ton/day/km2)
Note: Source; Ministry of the Environment of Japan (2005)

Figure 3-7 Relationship between TN load and average TN concentration in sea water− 69 −

Chapter3 MEASURES FOR THE CONSERVATION OF THE ENVIRONMENT OF THE SETO INLAND SEA'79-'83'84-'88'89-'93'94-'98'99-'03

Average TP Concentration

5.0

Tokyo Bay

4.0

3.0

Osaka Bay

2.0
Ise Bay
1.0
Seto Inland Sea (excluding the Osaka Bay)
0.0
0.00

0.01

0.01

0.02

0.02

0.03

0.03

0.04

Phosphorus Load per Unit Area of Water (ton/day/km2)
Note: Source; Ministry of the Environment of Japan (2005)

Figure 3-8 Relationship between TP load and average TP concentration in sea water

Trends in the achievement of Environmental Standard for COD, a typical indicator oforganic pollution, are shown in Figures. 3-9 and 3-10. The achievement of the environmental
standard of COD indicates that water quality in the Seto Inland Sea has been fully improvedby controlling the total amount loaded with 67% of the sites achieving the standard in 2004.
However, it also shows no marked improvement in recent years. The ratio of achievement insea zones classified as category A that cover large parts of the coastal seas of Japan, is at anespecially low level (60% for Japan as a whole but 28% in the Seto Inland Sea). Moreover, theSeto Inland Sea has been suffering from problems of eutrophication, which were caused by theabnormal reproduction of algae along with an increase in nutrients.
As mentioned in Chapter 2.4, nowadays, red tide, which is one example of the problemof eutrophication, occurs across a wide area of the Seto Inland Sea and 118 cases were observedin 2004. Most red tides appeared from March to November and damaged the fishery. On theother hand, discoloration of Nori (Porphyra) also has occurred of late and Nori production has
decreased markedly in recent years.
It is clear that there is a need to thoroughly implement a number of preservation andprotection measures even from now on.

− 70 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

(%)
100
90
80
70
60
50
40

All sea area of Japan
Seto Inland sea
Osaka Bay
Tokyo BayIse Bay

30
20
10
0
1975

1980

1985

1990

1995

2000

2005 Fiscal
Year

Note: Source; Ministry of the Environment of Japan (December, 2005)

Figure 3-9 Changes in Achievement Ratio of Environmental Standard in COD in the Main
Enclosed Coastal Seas in Japan

achievement rate
（％）
100
90
80
70
60
50
40
30

Category A
Category B
Category C
Whole Seto Inland Sea

20
10
0
1975

1980

1985

1990

1995

2000

2005 Fiscal
Year

Note: Source; Ministry of the Environment of Japan (December, 2005)

Figure 3-10 Changes in Achievement Ratio of Environmental Standard in COD in Classified
Zones in the Seto Inland Sea− 71 −

Chapter3 MEASURES FOR THE CONSERVATION OF THE ENVIRONMENT OF THE SETO INLAND SEA
3.7 DESIGNATION OF NATURAL SEASHORE CONSERVATION AREAS
It is a matter of both great importance and urgency that the remaining natural
seashores be conserved for recreation such as swimming in the Seto Inland Sea, because thenatural seashore has largely been lost as a result of various developments there. For this reason,
Article 12-7* of the Special Law for the Conservation of the Environment of the Seto Inland
Sea requires the prefectures concerned to designate seashores and sea zones facing the seashore
as "Natural Seashore Conservation Areas" by their ordinance which satisfy the following conditions :(1) those areas where sand beaches, reefs or other similar natural conditions are maintainednear the water-boundary line,(2) those areas which are used by the public for sea bathing, gathering sea shells and othersimilar purposes and which are recognized as being suitable for such use both at present
and in the future.
The notification requires that anyone who intends to build a new structure or conduct
other actions must assure the conservation of natural seashores and pleasurable use of the
Natural Seashore Conservation Areas.
Based on this Article, ordinance concerning the Natural Seashore Conservation Areas
has been drawn up in 11 of the prefectures concerned. Ninety-one zones were designated as
Natural Seashore Conservation Areas as of December 31, 2005. The location of these areas isshown in Figure 3-11.

Kyoto Pref.

Hyogo Pref.
Okayama Pref.

Osaka
Pref.

Hiroshima Pref.
Nara
Pref.
Kagawa Pref.

Yamaguchi Pref.

Tokushima Pref.
Ehime Pref.

Wakayama
Pref.

FukuokaPref.
Oita Pref.

0

10

20

30 km

Figure 3-11 Location of Designated Natural Seashore Conservation Areas＊: See : Appendix 6.5 SPECIAL LAW FOR THE CONSERVATION OF THE ENVIRONMENT OF THE SETO INLAND SEA− 72 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

3.8 REGIONAL ENVIRONMENTAL POLLUTION CONTROL PROGRAM
The Regional Environmental Pollution Control Program includes comprehensive enforcement,such as the restriction of effluent, the construction of sewers, the dredging of sludge deposited,the improvement of monitoring systems and so on, to achieve the environmental standards.
This plan has been drawn up in 13 zones in areas concerned with the Seto InlandSea, as shown in Figure 3-12. Although these 13 zones occupy only about 15% of the total area,
these areas, which have a high concentration of industry and people, have about 62% of the
population and produce 62% of the total amount of shipments.

Kyoto Pref.
Hyogo Pref.
Okayama Pref.
Hiroshima Pref.
Osaka
Pref.
Nara
Pref.
Yamaguchi Pref.

Kagawa Pref.
Tokushima Pref.
Wakayama
Pref.

Ehime Pref.
FukuokaPref.
Kyoto area
Osaka area
Hyogo area
Nara area
Wakayama area
Okayama・Kurashiki area
Bingo area

Oita Pref.

0

10

20

30 km

Hiroshima・Kure area
Syunan area
Shimonoseki・Ube area
Kagawa area
Kitakyusyu area
Oita area

Figure 3-12 Regional Environmental Pollution Control Program around the Seto Inland Sea

3.9 CONSTRUCTION AND IMPROVEMENT OF SEWERAGE AND OTHER
SYSTEMS
Although improvement of sewerage systems is indispensable to achieving the environmental
standards, the percentage of the population served by sewers in the 13 prefectures concernedwith the Seto Inland Sea was 28% in 1975 and 56% in 1996. These values are a little higher
than those for Japan as a whole, which were 23% in 1975 and 55% in 1996. Improvement innight soil treatment facilities has also progressed, since direct disposal into the Seto Inland Sea
was prohibited. However, a part of the night soil is directly disposed into the sea even now.
(1) Construction and Improvement of Sewerage Systems
Based on data from the Ministry of Construction, the population served by sewers increased
from 9,200,000 in 1975 to 24,400,000 in 2004.
(2) Construction and Improvement of Night Soil Treatment Facility
The total treatment capacity in the 13 prefectures concerned increased from 19,600 m3/day
at the beginning of 1980 to 29,900 m3/day by the end of 2003.
(3) Improvement in Household Wastewater Treatment Tanks (Jokaso)− 73 −

Chapter3 MEASURES FOR THE CONSERVATION OF THE ENVIRONMENT OF THE SETO INLAND SEA

Percentage of sewered population

(%)
100

3000
Percentage of sewered population (13 prefectures concerning the Seto Inland Sea)
Percentage of sewered population (national average)
Population served by sewer (13 prefectures concerning the Seto Inland Sea)

2500

80

2000
60
1500
40
1000
20

500

Population served by sewer (10thousand)On the basis of each of the guidelines, household wastewater treatment tanks andcombined treatment facilities have been improved. Several prefectures require advanced treatment
facilities to be constructed, and appropriate maintenance, including sludge withdrawal, has beenrequired.
Trends in the ratio of sewers provided and in the population served by sewers areshown in Figure 3-13. Trends in treatment capacity, the ratio of advanced treatment facilities
for night soil treatment, the population using household wastewater treatment tanks and theratio of people with combined tanks are shown in Figures 3-14 and 3-15, respectively.

0

0
1975

1985

1990

1995

2000

2005

Note: Source; Ministry of the Environment of Japan (December, 2005)

Figure 3-13 Changes in the Percentage of Sewer Served Population(%)
100(thousand m3/day)
100
Ratio of Advanced Treatment
Treatment Capacity (total)
Advanced treatment Capacity

90

80

80

70

70

60

60

50

50

40

40

30

30

20

20

10

10

0

0
1980

1985

1990

1995

1999

Note: Source; Data from each prefecture

Figure 3-14 Changes in Treatment Capacity and the Ratio of Advanced
Treatment Facilities for Night Soil Treatment− 74 −

Treatment Capacity

Ratio of Advanced Treatment

90

ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Population (10 thousand)
900
Single type Johkaso
Combined type Johkaso
800
700
600
500
400
300
200
100
0
1979

1984

1990

1995

2000

2004
FiscalYear

Note: Source; Data from each prefecture

Figure 3-15 Changes in Population Using Household Wastewater Treatment Tanks
and Population Ratio using Combined Tanks

3.10 CONSTRUCTION OF SOLID WASTE TREATMENT AND OTHER
FACILITIESWith regard to the daily discharged weight of solid waste per person in 2003, the averagevalue for Japan as a whole is 1,106 g/(person/day), while the average value for the 13 prefecturesconcerned with the Seto Inland Sea is 1,174 g/(person/day). In principle, solid waste is notincinerated but reduced in volume and stabilized by treatment. The incinerated ratio of solid
waste is 97.3% in the 13 prefectures concerned, which is almost the same as the average valueof 96.4% for Japan as a whole. The state of solid waste treatment and improvement in final
disposal sites are shown in Table 3-2 and 3-3, respectively.
Table 3-2 State of the Solid Waste Treatment (2003)
Pref.
All overe
Japan"(Unit: thousand tons)

Treatment Amount of Solid Waste
Planned Discharged Amount of Solid Waste Discharge
Total Collection
Amount Community
CoarsePopulation Population Planned Direct
Selfg per Collection Direct Direct High Rate Waste Recycling Others(thousand)Amount Incineration Landfill Composting(thousand) Collection Transport Treatment (person/day)
Treatment
127,507 127,365

Total

Reduction Recycled Recycle
Treatment
Ratio(%) Amount Ratio(%)

46,044

5,398

165

1,106

2,829

40,237

1,863

49

2,911

1,843

1,162

49,664

87.50

2,566

9.1

2,552

911

217

1

1,212

2,135

884

111

1

105

17

10

1,128

90.2

29

3.8

8,563

8,863

4,183

361

1

1,454

13

4,096

254

0

182

44

48

4,623

94.5

122

5

5,521

5,492

2,173

295

9

1,229

114

1,711

475

0

117

49

37

2,388

80.1

82

7.8

Kyoto

2,533

Osaka
Hyogo
Nara

1,425

1,421

408

77

6

943

37

392

18

0

53

10

11

485

96.3

26

12.1

Wakayama

1,080

1,073

347

83

8

1,111

5

330

39

0

20

6

35

430

90.9

31

8.3

Okayama

1,951

1,936

595

48

27

940

43

491

92

2

25

17

16

643

85.7

25

10

Hiroshima

2,894

2,853

905

87

21

959

24

716

135

0

41

74

27

993

86.4

82

10.4

Yamaguchi

1,563

1,528

479

129

16

1,093

19

421

134

0

27

19

6

608

77.9

22

6.5

Tokushima

840

820

247

19

23

943

10

194

28

0

24

15

5

266

89.4

19

10.4

Kagawa

1,028

1,022

305

42

4

935

14

253

73

0

5

6

9

347

79

16

8.2

Ehime

1,532

1,525

473

66

32

1,021

8

392

49

1

42

50

5

539

90.9

38

8.4

Fukuoka

4,879

4,809

1,696

241

17

1,097

67

1,609

79

1

159

85

19

1,950

96

98

8.2

Oita
Total ionthe 13 pref.

1,234

1,200

305

157

27

1,088

13

316

77

1

45

14

10

462

83.3

24

7.9

35,063

34,794

13,027

1,822

192

1,175

480

11,805

1,564

6

845

406

238

14,862

89.5

614

7.1

Note: Source; Ministry of Health and Welfare (Fiscal 1994)− 75 −

Chapter3 MEASURES FOR THE CONSERVATION OF THE ENVIRONMENT OF THE SETO INLAND SEA
Table 3-3 Improvement in Final Disposal Sites
Pref. etc

Number of Final Disposal Site
Mountain
Flat
Water
Sea
Total
Area
GroundBody

Japan as a
whole
Kyoto
Osaka
Hyogo
Nara
Wakayama
Okayama
Hiroshima
Yamaguchi
Tokushima
KagawaEhime
FukuokaOita
Total in the
13 Pref.

Area of
Total
Residual
Landfill
Capacity
Capacity(thousand m2) (thousand m2) (thousand m2)

1,675

31

26

660

2,392

51,557458,033

150,914

22
10
52
18
34
43
41
46
15
27
42
39
16

0
1
1
0
0
0
2
5
0
0
5
3
0

0
2
2
0
0
0
2
3
0
0
2
2
1

5
7
19
3
1
23
8
5
12
3
3
15
3

27
20
74
21
35
66
53
59
27
30
52
59
20

841
1,200
2,304
296
530
1,046
1,331
1,169
218
427
1,126
3,646
650

6,720
15,66736,051
1,654
3,402
6,033
9,580
5,923
1,445
2,836
3,859
32,433
4,345

1,936
5,707
15,582
746
1,533
1,727
4,766
1,915
169
1,161
1,713
8,586
1,739

405

17

14

107

543

14,784

129,948

47,280Note: Source; Ministry of Health and Welfare

3.11 CONSTRUCTION OF WASTE OIL TREATMENT AND OTHER FACILITIESTreatment facilities for waste oil from vessels were constructed at 51 sites at 24 ports
as of October 2005. Seventeen oil-recovery ships, 20 cleaning ships and 11 combined oil-recovery
and cleaning ships were established in January 2005, as shown in Table 3-4.
Table 3-4 Waste Oil Treatment and Other Facilities in the Seto Inland Sea
Classification

Waste Oil
Treatment
Facilities(Number)

Spilled Oil
Recovery Ships(Number)

Waste Cleaning
Ships(Number)

Oil-Recovery &Waste-Cleaning
Ships(Number)

Ministry of Transport

―

1

6

10

Japan Coast Guard

―

5

0

0

Prefecture

6

0

8

1

City, Town and Village

2

1

6

0

Private Company, etc

43

10

0

0

Total

51

17

20

11

Note

Includes one
Defense Agency
facility

Includes one
Defense Agency
facility

Note: Source; Spilled Oil Recovery Ships, Waste Cleaning Ships and Oil-Recovery & Waste-Cleaning Ships, The Japan
Workvessel Association.

3.12 RESTRICTIONS BASED ON THE SPECIAL LAW FOR THE CONSERVATION
OF THE ENVIRONMENT OF THE SETO INLAND SEA
If the governors of the prefectures concerned give permission for the reclamation of
public water areas, The Special Law for the Conservation of the Environment of the Seto Inland
Sea forces them to take the special features of the sea into consideration. The principle forthe reclamation was submitted to the Environment Agency of Japan in May, 1974 from the
Seto Inland Sea Environmental Conservation Council, as outlined below.

− 76 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Outline of the Principle for Reclamation in the Seto Inland Sea
This Principle was established based on the following law:
THE SPECIAL LAW FOR THE CONSERVATION OF THE ENVIRONMENTOF THE SETO INLAND SEA
Outline of the Basic Policy for Reclamation(Preamble) Reclamation of the Seto Inland Sea should be strictly controlled, and if it
is authorized for an unavoidable reason it should be conducted in accordance withthe policies described below
1. Regional Policy
PolicyRegion(1) Every effort should bemade to avoid
reclamation

Designated environmental conservation areas① special areas designated by the Natural Parks Law② special areas designated by the Natural
Environment Conservation Act③ special areas designated by the Wildlife ProtectionLaw④ historic relics, scenic spots, natural monuments andother areas designated by law as fishery reserves(2) Reclamation that does
not comply with thosematters mentioned
below should be
avoided if at all possible.

Specified sea areas seriously polluted with a highdegree of stagnation (6 sea areas)(matters for consideration)・factors that contribute to pollution andenvironmental conservation
・things for which certain facilities described in the
Water Pollution Control Law have not been
established.
・small pollution load of effluents, etc.
(3) Confirming matters forgeneral consideration

all sea areas

2. Matters for General Consideration(1) conservation of the sea area environment...only slightly affected by water pollution(2) conservation of the natural environment...only slight effect on ecosystem andnatural beauty(3) conservation of living aquatic resources...only slight effect on fishery industry− 77 −

Chapter3 MEASURES FOR THE CONSERVATION OF THE ENVIRONMENT OF THE SETO INLAND SEA
Specified Sea Area
Seriously polluted with a high degree of stagnation

Kyoto Pref.
Hyogo Pref.

Northern Harima-bada
Osaka
Pref.

Okayama Pref.

Mizushima-nada

Osaka
bay

Hiroshima side of Aki-nada & Hiroshima bay

Harima-nada

Tokuushi Lighthouse

Kagawa side of Harima-nada

Bingo-nada
Hiroshima bay

Yamaguchi Pref.
Hinoyamashita
Lighthouse

Depth of Osaka bay Nara Pref.

Bisan-seto

Hiroshima Pref.

Tsunozima-tsuuse Cape

Kagawa Pref.
Aki-nada

Kii Channel

Hiuchi-nada

Tokushima Pref.

Hibiki-nada
Mojizaki Lighthouse

Ehime side of Hiuchi-nada

Myokenzaki
LighthouseKii Hinomisaki
Lighthouse
Gamoda Cape

Suo-nada

FukuokaPref.

Iyo-nada

Wakayama Pref.

Ehime Pref.

Sata Cape
Sekizaki Lighthouse

Oita Pref.

Special Sea Area

Bungo Channel

LegendTsurumi Cape

Boundary among Prefectures

Takamo Cape
0

10

20

30 km

Area of the Seto Inland Sea

Name of Sea Area

Location

Osaka Bay

Zone between the left side of the mouth of Ozato
river, Hannan-cho, Sennan-gun, Osaka Pref. and theright side of the mouth of Myohoji river, Suma-ward,
Kobe-City, Hyogo Pref.

Northern Harima-nada

Zone between the light house at the Eigashima port,
Hyogo Pref. and the tip of the Desaki Cape, Okayama
Pref.

Kagawa side ofHarima-nada

Zone between the point of the Umagahana, Shido-cho,
Okawa-gun, Kagawa Pref. and the left side of the
Kato river, Takamatsu City, Kagawa Pref.

Mizushima-nada

Zone between the point of the Nishinohana, Shimotsui,
Kurashiki City, Okayama Pref. and the Abuto lighthouse, Hiroshima Pref.

Ehime side of Hiuchi-nada

Zone between Yokizaki, Kawanoe city, Ehime Pref.
and the point of Osumihana, Hakata-cho, Ehime Pref.

Hiroshima side of Aki-nada& Hiroshima Bay

Zone between the light signal of Shigeiwa,
Todahigashi, Nikata-cho, Kure city, Hiroshima Pref.
and the Setoyamahana, Obata Town, Yamaguchi Pref.

− 78 −

Chapter 4 FUTURE TASKS AND CHALLENGES FACING
THE SETO INLAND SEA
4.1

NEW ENVIRONMENTAL POLICIES

4.2 POSSIBLE IMPROVEMENT IN HABITAT CONDITIONS

80
80

AND LIVING RESOURCES
4.3 SOME CASES OF ENVIRONMENTAL RESTORATION80

IN THE SETO INLAND SEA
4.4 FUTURE DIRECTION

81− 79 −

Chapter4 FUTURE TASKS AND CHALLENGES FACING THE SETO INLAND SEA
4.1 NEW ENVIRONMENTAL POLICIESNew environmental policies contributing to the recovery of a sound environment were
officially introduced to the Seto Inland Sea in 2000 (the 5th water quality control policy wasconfirmed). Based on previous environmental conditions, the main target of the policy waschanged from water quality control to environmental remediation and restoration of habitat.
Led by the new policy for the Seto Inland Sea, a new law on the restoration of natural environments
was enacted in 2002. This new law was applied not only to the Seto Inland Sea but also all
over Japan. Collaboration among various groups, such as local and national governments, local
residents, NGOs, not-for-profit organizations (NPOs), scientists, and fishermen are expected toplay an important role in promoting individual restoration projects.
Moreover, the 6th water quality control policy was decided in 2006, where the totalloads control policy for COD, TP and TN will be continued only in Osaka Bay but it will beabolished in other bays and nadas of the Seto Inland Sea.
The new basic ocean law was enacted in July 2007, where the new minister of ocean
takes the responsibility in all the governmental activities related to marine affairs and marine
environment.

4.2 POSSIBLE IMPROVEMENT IN HABITAT CONDITIONS AND LIVINGRESOURCES
Four possible causes for the decrease in fish stocks in the Seto Inland Sea have been
proposed, namely 1) changes in the natural environment due to a regime shift (large scale
climatic and oceanographic changes), 2) overfishing, 3) destruction of spawning and nursery
grounds or habitats, and 4) long term changes in the ecosystem due to the effect of humanactivities. Decreases in sand eel stocks were more directly affected by habitat destruction due
to large-scale sea-sand dredging for concrete construction industries, although sea-sand dredging
in the Seto Inland Sea was prohibited in 2006.
Among the four possible causes identified above, countermeasures against regime shift
and long-term ecosystem change are very difficult or almost impossible to be achieved in a
relatively short period of time. Realistic countermeasures can only be taken against overfishing
and against destruction of spawning and nursery grounds or habitats. Here lies the importanceof habitat restoration - in particular of tidal flats and seaweed beds - and of living resource
management in shallow areas.
In shallow coastal waters, seaweed beds are important habitats and reproduction
grounds for many marine organisms. Tidal flats are the most important production area forbivalves. They also play an important role in the decomposition of organic matter. Both ofthese important habitats have been undergone long-term decreases in the Seto Inland Sea area.
Between 1978 and 1991, 1,500 ha of seaweed beds and 800 ha of tidal flats were lost from the
Seto Inland Sea, mainly due to reclamation, dredging or other human activities. As a result, asignificant portion of natural coastline has been converted to man-made coastline, consisting of
upright concrete structures. These have not provided a good habitat for many organisms living
along the seashore, nor have they provided the valuable functions of a natural coastline suchas purification of organic pollution and de-nitrification.

4.3 SOME CASES OF ENVIRONMENTAL RESTORATION IN THE SETO
INLAND SEA
Of the many enclosed coastal seas of Japan, the Seto Inland Sea is one of the mainsites for environmental remediation and restoration. Remediation and restoration carried out bydifferent organizations in the Seto Inland Sea covers a variety of methods, depending on theirobjectives. Some examples include the simple restoration of tidal flats or seaweed beds, or a

− 80 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

combination of tidal flats and seaweed beds, artificial rocky shores, artificial lagoons, artificial
submerged slopes, re-use of dredged sediments and bird sanctuaries. Some typical examples ofsuch activities are introduced below.
1) At the estuary of the Fushino River in Yamaguchi Prefecture, very comprehensive
habitat restoration is being conducted, including the environmental remediation of theFushino River watershed. Reforestation of the upstream area is also included in thisproject. A local currency, called Fushino, was introduced to the area in order topromote the project which was supported by the wide variety of stakeholders.
2) Etashima Bay in Hiroshima Prefecture has a highly enclosed topography and is an important
ground for the culture of oysters. Oxygen depletion in the bottom water in summer
and deterioration in sediment quality, have been serious problems there. The local
government of Hiroshima Prefecture initiated the restoration of Etashima Bay using a
multi-sectoral approach in which five prefectural research institutes participated in thedevelopment of efficient tidal flats and sea grass beds in order to activate local fisheries
and oyster culture.
3) Along the coast of Kansai International Airport, which is located on an artificial island
in Osaka Bay, a gentle slope of natural rocks and stones rather than a vertically uplifted
concrete wall was used in the construction of the airport. This environmentally friendly,
gentle slope provided an appropriate site for seaweed beds and a suitable habitat for
many kinds of organisms. As a result, the artificial structure is now working as a newseaweed bed and habitat. As the original site on which the airport was constructed
was an area of muddy sea bottom, this is a good example of environmentally friendly,
creative regeneration of the environment. Although the effect of the artificial island
should be evaluated correctly, the effect of a more natural gentle slope itself should also
be evaluated since the newly created seaweed bed plays a mitigating role in the widely
lost seaweed bed in Osaka Bay.
As to restoration of the effects of large-scale sea-sand dredging, environmental change
is being monitored and the basic design for a restoration plan has been discussed but practicalrestoration activities have not yet been achieved.

4.4 FUTURE DIRECTIONS
The results of the preliminary examination of the environmental health of the Seto
Inland Sea made clear the deterioration in habitat conditions. Hence, restoration of such habitats
in shallow water, including tidal flats and seaweed beds, is one of the most pressing actions
that needs to be taken in the Seto Inland Sea. Therefore, one of the major directions in future
should be creative restoration and possibly, the creative regeneration of a new Seto Inland Sea(Matsuda, 2007).
A new concept, "Sato Umi", was proposed by the Research Institute for the Seto Inland
Sea. "Sato Umi" means, in Japanese, a coastal sea under the harmonization of sustainable, wise
use with conservation of an appropriate natural environment and habitat (Yanagi, 2007). Comparedwith a deteriorating coastal environment, "Sato Umi" is able to provide a higher biologicaldiversity as habitat, and higher biological production as fishing grounds. These characteristicsof "Sato Umi" are also suitable for demonstrating the multi-functional roles of fisheries.
Development of a new holistic approach for sustainable biological production and controlof eutrophic levels is a prerequisite for establishing functionally efficient "Sato Umi" in each
local coastal area. It is recommended the promotion of integrated environmental management
towards environmental remediation and restoration of a wide variety of habitats be undertaken− 81 −

Chapter4 FUTURE TASKS AND CHALLENGES FACING THE SETO INLAND SEA
in the near future. This should involve the international exchange of information, ideas andmethodologies.
However, with respect to the future direction of habitat conservation and resource
management, top priority should be given to the original objective. In the case of seaweed bed
restoration, this includes the high performance restoration of seaweed beds. However, otherviewpoints are also important. Future methods of habitat restoration and resource management
should be examined from the viewpoint of low environmental impact, high recycling of material
used, low cost with high cost performance, energy saving technology, and applicability ofadaptive management. Continuous monitoring after restoration activities is also very importantin evaluating the effectiveness of the restoration methods that have been used.
Important and practical future directions are itemized below:
Active creation of a new environment in the Seto Inland Sea
蘆 Preferable habitat environments and recreational spaces to recover seaweed beds, tidal
flats and other shallow water areas
蘆 The strict control of reclamation and excavation
蘆 Promoting fisheries from the view point of the multi-functional role of fisheries
Regeneration of forests, rivers and the sea, with effective participation and partnerships among thevarious stakeholders
蘆 Preferable water and material cycling, recognizing the interactions between forests, river
basins and coastal seas
Establishment of mitigation systems
蘆 Minimizing waste dumping in the area
蘆 The wise and efficient use of vacant land along the coast
蘆 Securing new environments in areas that are disappearing but of historical significanceComprehensive management
蘆 Wide-ranging cooperation among the national government, local governments, local citizens,companies and other entities
A unified authority to be organized with all rights on management of the Seto Inland
Sea
In conclusion, the development of a new holistic approach for sustainable biologicalproduction and control of eutrophic levels, or a kind of new creative restoration, is a priority.
Promotion of integrated environmental management, including watershed management, should
be adopted from the viewpoint of interrelated water and material cycling in the river basin,
forest and coastal seas. The concept of "Sato Umi", originating from the traditional ideas of thelocal people for the wise and sustainable use of coastal areas, can support this new creative
restoration of the environment and habitat in the Seto Inland Sea.

− 82 −

Chapter 5 REFERENCES
5REFERENCES− 83 −

84

Chapter5 REFERENCES
5.REFERENCES
2.4 OCCURRENCE OF RED TIDES
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Fisheries Agency (2000) Red Tides in the Seto Inland Sea and Fisheries Damage (1970〜1998).
112 pp. (in Japanese)
Fisheries Agency (2005) Red Tides in the Seto Inland Sea (2004). 70 pp. (in Japanese)
Fisheries Agency (2006) Red Tides in the Seto Inland Sea (2005). 73 pp. (in Japanese)
Fukuyo Y, Imai I, Kodama M, Tamai K (2002) Red tides and other harmful algal blooms inJapan. In: Harmful Algal Blooms in the PICES Region of the North Pacific, PICES Scientific
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Furuhata K, Kakino J, Miyama Y, Fukuyo Y (1996) Elimination of cysts of the toxic dinoflagellates
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Hallegraeff G (1993) A review of harmful algal blooms and their apparent global increase.
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Hiroshima Prefecture (1996) Manual on Countermeasures for Red Tides in Hiroshima Prefecture.
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Honjo T (1992) Harmful red tides of Heterosigma akashiwo. NOAA Technical Report NMFS 111: 27-32.
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found in bottom sediments of northern Hiroshima Bay, Japan. Nippon Suisan Gakkaishi 59:
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Imai I, Itoh K (1987) Annual life cycle of Chattonella spp., causative flagellates of noxious red
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Imai I, Itoh K (1988) Cysts of Chattonella antiqua and C. marina (Raphidophyceae) in sedimentsof the Inland Sea of Japan. Bull Plankton Soc Japan 35: 35-44.
Imai I, Sugioka H, Nishitani G, Mitsuya T, Hamano Y (2003) Monitoring of DSP toxins in small-sizedplankton fraction of seawater collected in Mutsu Bay, Japan, by ELISA method: relation withtoxin contamination of scallop. Mar Poll Bull 47: 114-117.
Imai I, Yamaguchi M, Hori Y (2006) Eutrophication and occurrences of harmful algal blooms in
the Seto Inland Sea, Japan. Plankton Benthos Res 1: 71-84.
Itakura S, Yamaguchi M (2001) Germination characteristics of naturally occurring cysts of
Alexandrium tamarense (Dinophyceae) in Hiroshima Bay, Inland Sea of Japan. Phycologia 40:
263-267.
Iwataki M, Wong MW, Fukuyo Y (2002) New record of Heterocapsa circularisquama (Dinophyceae)
from Hong Kong. Fisheries Sci 68: 1161-1163.

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Kim DI, Nagasoe S, Oshima Y, Yoon YH, Imada N, Honjo T (2004) A massive bloom of
Cochlodinium polykrikoides in the Yatsushiro Sea, Japan in 2000. In: Harmful Algae 2002 (eds.
Steidinger KA, Landsberg JH, Tomas CR, Vargo GA). Florida Fish and Wild Life Conservation
Commission and IOC-UNESCO, St. Pete, Florida, pp. 83-85.
Kim HG, Lee SG, Jeong CS, Bae HM (2002) Current situation of harmful algal blooms and mitigation
strategies in Korean coastal waters. In: Prevention and Extermination Strategies of Harmful
Algal Blooms (eds Hiroishi S, Imai I, Ishimaru T). Koseisha-kouseikaku, Tokyo, pp. 134-150. (inJapanese)
Koizumi Y, Kohno J, Matsuyama Y, Uchida T, Honjo T (1996) Environmental features and themass mortality of fish and shellfish during the Gonyaulax polygramma red tide occurred inand around Uwajima bay, Japan, in 1994. Nippon Suisan Gakkaishi 62: 217-224. (in Japanesewith English abstract)
Kotani Y, Koyama A, Yamaguchi M, Imai I (1998) Distribution of resting cysts of the toxic
dinoflagellates Alexandrium catenella and/or A. tamarense in the coastal areas of western Shikoku
and Kyushu, Japan. Bull Jpn Soc Fish Oceanogr 62: 104-111. (in Japanese with English abstract)
Kotani Y, Tamai K, Yamaguchi M, Okubo S, Matui K, Nakamura T (2004) Historical and current
status of red tides and shellfish poisonings in Japan. In: Harmful Algae Management and
Mitigation (eds Hall S, Etheridge S, Anderson DM, Kleindinst J, Zhu M, Zou Y). APEC Publication,
Singapore, pp. 25-33.
Kumamoto Prefecture (1980) The annual report for the developments of countermeasures to
red tides (1979): Examination of clay spraying for flocculation of red tides. 43pp. (in Japanese)
Manabe T, Ishio S (1991) Bloom of Coscinodiscus wailesii and DO deficit of bloom water in Seto
Inland Sea. Mar Poll Bull 23: 181-184.
Matsuoka K, Iwataki M (2004) Present status in study on a harmful unarmored dinoflagellate
Cochlodinium polykrikoides Margalef. Bull Plankton Soc Japan 51: 38-45. (in Japanese with English
abstract)
Matsuyama Y (1999) Harmful effect of dinoflagellate Heterocapsa circularisquama on shellfish
aquaculture in Japan. JARQ 33: 283-293.
Montani S (2000) Ecological approaches to environmental management in fishing farm. In: Mechanisms,
Prediction, and Mitigation of Harmful Algal Blooms in Japan (eds Ishida Y, Honjo T, Fukuyo
Y, Imai I). The Japan Fisheries Resource Conservation Association, Tokyo, pp. 236-256. (inJapanese)
Nagai S (2000) Occurrence mechanisms and prediction of the blooms of a giant diatom Coscinodiscus
wailesii. In: Mechanisms, Prediction, and Mitigation of Harmful Algal Blooms in Japan (eds
Ishida Y, Honjo T, Fukuyo Y, Imai I). The Japan Fisheries Resource Conservation Association,
Tokyo, pp. 71-100. (in Japanese)
Okaichi T (1997) Red tides in the Seto Inland Sea. In: Sustainable Development in the Seto
Inland Sea, Japan - From the Viewpoint of Fisheries (eds Okaichi T, Yanagi T). Terra Scientific
Publishing Company, Tokyo, pp. 251-304.
Shiraishi T, Hiroishi S, Taino S, Ishikawa T, Hayashi Y, Sakamoto S, Yamaguchi M, Imai I (2008)
Identification of overwintering vegetative cells of the bivalve-killing dinoflagellate Heterocapsa
circularisquama in Uranouchi Inlet, Kochi Prefecture, Japan. Fisheries Sci 73 : in press
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In: Physiological Ecology of Harmful Algal Blooms (eds Anderson DM, Cembella AD, Hallegraeff
GM). Springer, Berlin, pp. 113-131.
Smayda TJ (2002) Adaptive ecology, growth strategies and the global bloom expansion of
dinoflagellates. J Oceanogr 58: 281-294.
Tamai K (1999) Current status of outbreaks and fisheries damages due to Heterocapsa circularisquama.
Bull Plankton Soc Japan 46: 153-154. (in Japanese with English abstract)
Yamaguchi M, Itakura S, Imai I, Ishida Y (1995) A rapid and precise technique for enumerationof resting cysts of Alexandrium spp. (Dinophyceae) in natural sediments. Phycologia 34: 207-214.
Yamaguchi M, Itakura S, Nagasaki K, Imai I (1996) Distribution and abundance of resting cysts− 85 −

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of the toxic dinoflagellates Alexandrium tamarense and A. catenella in sediments of the eastern
Seto Inland Sea, Japan. In: Harmful and Toxic Algal Blooms (eds Yasumoto T, Oshima Y,
Fukuyo Y). IOC-UNESCO, Paris, pp. 177-180.
Yamaguchi M, Itakura S, Nagasaki K, Kotani Y (2002) Distribution and abundance of restingcysts of the toxic Alexandrium spp. (Dinophyceae) in sediments of the western Seto InlandSea, Japan. Fisheries Sci 68: 1012-1019.
Yamaguchi M, Itakura S, Nagasaki K, Matsuyama Y, Uchida T, Imai I (1997) Effects oftemperature and salinity on the growth of the red tide flagellates Heterocapsa circularisquama(Dinophyceae) and Chattonella verruculosa (Raphidophyceae). J Plankton Res 19: 1167-1174.
Yamaguchi M, Yamaguchi H, Nishitani G, Sakamoto S, Itakura S (2008) Morphology and germination
characteristics of the cysts of Chattonella ovata (Raphidophyceae), a novel red tide flagellate in
the Seto Inland Sea, Japan. Harmful Algae 7: in press.
Yamatogi T, Sakaguti M, Takagi N, Iwataki M, Matsuoka K (2005) Effects of temperature, salinity
and light intensity on the growth of a harmful dinoflagellate Cochlodinium polykrikoides Margalef
occurring in coastal waters of West Kyushu, Japan. Bull Plankton Soc Japan 52: 4-10. (inJapanese with English abstract)
Yoon YH (2001) A summary on the red tide mechanisms of the harmful dinoflagellate, Cochlodinium
polykrikoides in Korean coastal waters. Bull Plankton Soc Japan 48: 113-120. (in Japanese withEnglish abstract)
Yuki K, Yoshimatsu S (1989) Two fish-killing species of Cochlodinium from HarimaNada, Seto
Inland Sea, Japan. In: Red Tides: Biology, Environmental Science, and Toxicology (eds Okaichi
T, Anderson DM, Nemoto T). Elsevier, NY, pp. 451-454.
2.5 MARINE POLLUTION BY OIL SPILLS AND OTHER CAUSES
Association for the Environmental Conservation of the Seto Inland Sea (2006) Environmental
Conservation of the Seto Inland Sea, 2004 Data. 163 pp. (in Japanese)
Fisheries agency (2006) Explanatory Pamphlet on Dioxins in Seafood. 13 pp. (in Japanese)
Horiguchi T (2000) Endocrine disruptors in wild animals, and the chemicals responsible for thephenomenon: Molluscs. In: Problems of Endocrine Disruptors in Fisheries Environment (eds
Kawai S, Koyama J). Koseisha-kouseikaku, Tokyo, pp. 54-72. (in Japanese)
Horiguchi T, Shiraishi H, Shimizu M, Morita M (1997) Imposex in sea snails, caused by organotin(tributyltin and triphenyltin) pollution in Japan: a survey. Appl Organomet Chem 11: 451-455.
International EMECS Center (1999) Environmental Conservation, the Seto Inland Sea. 57 pp.
Ishii J (1998) A long-term volunteer activity. In: Heavy Oil Pollution: For Tomorrow, Can"Nakhodka"Change Japan? (ed Ocean Engineering Research). Ocean Engineering Research, Inc,Tokyo, pp. 80-106. (in Japanese)
Kawai S, Yamamoto Y (2004) Human and Environment in the Future, 3rd eds. Kagaku-Dojin,
Kyoto, 270 pp. (in Japanese)
Kojima A (2005) On the activity of JEAN. Sci Forum Seto Inland Sea 42: 1-7. (in Japanese)
Komatsu T, Nakaoka M, Kawai H, Yamamoto T, Marine Life Research group of Takeno, Ohwada
K (2005) Impact assessment of the heavy-oil pollution on the intertidal ecosystems after the'Nakhodka' oil spill by using GIS. In: Effects of Oil Spill Accidents onto Marine Environmentswith Special Attention to Nakhodka Case (eds Ohwada K, Koyama J, Hiroishi S). Koseishakouseikaku, Tokyo, pp. 120-134. (in Japanese)
Kurashige K (2004) The trends of the marine debris problem in Japan. Bull Kagoshima Women'sColl 39: 71-78.
Maruyama A (2005) Marine oil-degrading microbes and bioremediation. In: Effects of Oil Spill
Accidents onto Marine Environments with Special Attention to Nakhodka Case (eds Ohwada
K, Koyama J, Hiroishi S). Koseisha-kouseikaku, Tokyo, pp. 54-73. (in Japanese)
NOAA Marine Debris Program: http://marinedebris.noaa.gov/
Okaichi T (1997) Marine environmental problems caused by oil spill. J Jpn Soc Water Environ− 86 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

20: 632-638. (in Japanese)
Okaichi T, Tatsumi S (1975) Heavy Oil Pollution in the Seto Inland Sea: Monitoring Record andRemote Sensing. Shorinsha, Takamatsu, 182 pp. (in Japanese)
Schecter A, Birnbaum L, Ryan JJ, Constable JD (2006) Dioxins: An overview. Environ Res 101:
419-428.
Setouchi Net: http://www.seto.or.jp/seto/index.htm
Shiwaku S (2005) Real status of marine debris on the sea bottom floor in the Seto Inland Sea- Investigation record collected by Mizushima Foundation. Sci Forum Seto Inland Sea 42: 8-12.
(in Japanese)
U.S. EPA: http://www.epa.gov/owow/oceans/debris/
Yamada H (1999) Studies on behaviour of organotin compounds in marine environment andbioaccumulation by marine fish. Bull Natl Res Inst Fish Environ Inland Sea 1: 97-162.
3.6 POLLUTANT LOADS AND THEIR CONCENTRATION IN THE SURFACE WATER IN
THE SETO INLAND SEA
Matsuda, O. : Chapter, Environmental problems in coastal zone. In "Asia-Pacific Coasts andTheir Management : States of Environments", ed. By N.Mimura, Springer, New York.
4.4 FUTURE DIRECTION
Matsuda, O. : Chapter, Environmental problems in coastal zone. In "Asia-Pacific Coasts andTheir Management : States of Environments", ed. By N.Mimura, Springer, New York.
Yanagi,T. (2007) Sato-Umi -New concept for coastal sea management-. Terra Scientific Publishing
Company, Tokyo. 86 p.

− 87 −

Chapter 6 APPENDIXCONTROL LAW SYSTEM IN A COASTAL ZONE

90

6.2 ENVIRONMENTAL CHRONOLOGY OF JAPAN91

6.3 AREA-WIDE TOTAL WATER POLLUTANT LOAD CONTROL

93

6.1

SCHEME FOR ENCLOSED COASTAL SEAS IN JAPAN ;PROGRESS AND FUTURE DIRECTION
6.4 MEASURES TO PREVENT EUTROPHICATION IN ENCLOSE

102

COASTAL SEAS
6.5 THE SPECIAL LAW FOR THE CONSERVATION OF THE

104

ENVIRONMENT OF THE SETO INLAND SEA
6.6 BASIC ACT ON OCEAN POLICY− 89 −

114

Chapter6 APPENDIX
6.1 CONTROL LAW SYSTEM IN A COASTAL ZONE
The control law system which made a coastal region the subject is various.
The use of coastal zone and the main legal system about environment protection are as follows.

（Comprehensive National Land Use）
・Comprehensive National Land Development Law
・The National Land Use Planning Act
・The Act Concerning Development of Osaka Bay Areas（Land Use）

・Public Water Body Reclamation Law

・City Planning Law
・Forest Law
・Agricultural Land Act
・Land Improvement Law
・Factory Location Law
・Promotion of Power Resources
Development Law（Fishery）
・Fisheries Law, Law on Provisional Measures
Relating to the fisheries Zone
・Fisheries resources Protection Act
・Promotion of Marine Fishery Resources
Development Law (Tentative Name)
・Coastal Fisheries Grounds Enhancement andDevelopment Program Law
・Fishing Port Law（Mineral Resources）
・Quarrying Law

・Gravel Extraction Law
・Mining Law（Marine Traffic）
・Port Regulation Law
・Marine Transportation Law
・Law for Preventing Collisions at Sea
・Regulation for the Carriage and Storage ofDangerous Goods in the Ships
・Port and Harbor Law（National Land Conservation）
・Sand Control Law

・River Law

・The Seacoast Law（Waste／Marine）
・Law Relating of the Prevention of Marine Pollution
and Maritime Disaster
・Law of Regional Offshore Environmental Improvement Center・Waste Disposal and Public Cleansing Law（Environmental Conservation）
・Environment Basic Law
・Natural Conservation Law
・Natural Parks Law
・Environmental Impact Assessment Law
・Water Pollution Control Law
・Sewage water Law
・Law Concerning Provisional Measures for Conservation of the Environment of the Seto Inland Sea
・Law Regulating the Commercial transactions in Endangered Species of Wild Fauna and Flora・Wildlife Protection and Hunting Law
Territorial-sea Law

Continental Areas

Waterfront Line

Marine Area

Note ：This figure takes up a typical law related to use in area of sea and conservation, put it inorder, didn't net any laws and doesn't also choose an expression as strict legal interpretation.
Source：Environment protection council of the Seto Inland Sea 4th planning meeting(1998.7.2)submission material− 90 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

6.2 ENVIRONMENTAL CHRONOLOGY OF JAPAN
FY

EVENT

1891

The Ashio Copper Mine issue discussed in Diet session

1897

Ashio Copper Mine Pollution Investigation Group organized

1948

Agricultural Chemical Registration Law enacted

1949

Mine Safety Law enacted
Tokyo Metropolitan Regulation to Control Factory Pollution enacted

1956

Minamata Health Center discovers a 'strange disease 'Industrial Water Law enacted

1958

Water Quality Conservation Law and Factory Effluent Control Law enacted
Sewerage Law enacted

1961

Foul odor from fish on and off the Coast of Mizuhima becomes an issue
Law Concerning the Regulation of Pumping-up of Ground Water for Use in
Buildings enacted

1965

Special Committee for Environmental Pollution established in both the Upper andLower Houses
Second outbreak of Minamata disease along the Agano River (Niigata)

1967

Basic Law for Environmental Control enacted

1970

Headquarters for Countermeasures for Environmental Pollution established
Environmental Quality Standards for Water Pollution established at cabinet meeting
Basic Law for Environmental Pollution Control amended, Water Pollution Control
Law enacted, and Agricultural Land Soil Pollution Prevention Law enacted (atthe 'Environmental Diet')

1971

Environment Agency establishedCentral Council on Environmental Pollution Control established
Agricultural Chemical Registration Law (Standard for withholding registration
strengthened, among other changes) amended

1972

Large-scale red tide in the Seto Inland Sea damages fisheries
Water Pollution Control Law amended (Absolute liability introduced)

1973

The Interim Law for Conservation of the Environment of the Seto Inland Sea
enacted1978

The Basic Plan for Conservation of the Seto Inland Sea approved
The special law for the conservation of the environment of the Seto Inland Sea
enacted Water Pollution Control Law amended (Areawide total water pollutant
load control institutionalized)

1979

Areawide total pollutant load control implemented in Tokyo Bay, Ise Bay and theSeto Inland Sea

1980

Request for voluntary restraint from use of organic phosphorus detergent

1981

The Prefectural Plan for Conservation of the Environment of the Seto Inland Sea
established

1984

The Special Law for the Conservation of the Environment of the Seto Inland Sea
enacted− 91 −

Chapter6 APPENDIX
FY

EVENT

1985

Nitrogen and phosphorus control standards relating to lakes and reservoirs were
established Outline of Measures for Preventing Ground Subsidence for the Nobi
Plain and Chikugo-Saga Plain established1987

Second areawide water pollutant load control implemented

1989

Setting of regulatory standards for trichloroetheylene and tetrachloroetheylene
Water Pollution Control Law amended (Preventive measures against groundwaterpollution institutionalized)

1990

Water Pollution Control Law amended (Measures against domestic effluent
institutionalized)

1991

Third areawide water pollutant load control implemented
Outline of Measures for Preventing Ground Subsidence for the northern part of
Kanto Plain established
Environmental Quality Standards for soil established1993

The Ministry of Environment adds many new substances to Environmental
Quality Standards relating to the protection of human health, and makes standard
values more stringent
Basic Environment Law enacted

1994

Basic Environment Plan approved by the cabinet
Law to Take Special Measures for the Preservation of Water Quality in
Headwaters Areas for the Purpose of Preventing Specific Trouble in the
Drinking Water Supply enacted
Scope of the Environment Quality Standards for Soil made tougher and broader
in scope

1995

National Contingency Plan for Preparedness and Response to oil pollution

1996

Water Pollution Control Law amended (Institutionalization of measures against
groundwater pollution and oil flown out by accidents）
Fourth areawide water pollutant land control implemented

1997

Environmental Quality Standards for Groundwater established1998

Human-health items of water quality standard increased in strictness and scope

1999

Law Concerning Special Measures Against Dioxins
Policies for investigation and countermeasures for soil and groundwater were
established

2000

New Basic Environment Plan approved by the cabinet
Basic plan for environmental conservation of Seto Island Sea completely amended

2001

Ministry of the Environment established
Fourth areawide water pollutant land control implemented

2002

Soil Pollution Control Law enacted
Law on Special Measures to Restore the Ariake and Yastsuhiro Seas enacted

2003

Basic Law on Restoration of the Ariake and Yashiro Seas enacted
Ariake and Yatsushiro Sea Study Council established2007

Basic Act on Ocean Policy enacted− 92 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

6.3 AREA-WIDE TOTAL WATER POLLUTANT LOAD CONTROL SCHEME
FOR ENCLOSED COASTAL SEAS IN JAPAN ; PROGRESS AND
FUTURE DIRECTION
Office of Environmental Management of Enclosed Coastal Seas,
Environmental Management Bureau, Ministry of the Environment.
1-2-2 Kasumigaseki, Chiyoda-ku, Tokyo 100-8975, Japan
Abstract
The area-wide total pollutant control system has been implemented in order to prevent
water pollution in the Tokyo Bay, the Ise Bay and the Seto Inland Sea for every five
years since 1979. Under the system, a target amount of reduction in terms of chemical
oxygen demand (COD), nitrogen and phosphorus was established to be achieved in eachsea area by target year. At present, relevant measures are being implemented based on
the 5th total pollutant load control program with the target year 2004.
In respond to the request of the Minister of the Environment, the Central Environment
Council, Minister's advisory board, set up an expert committee in 2004 to formulate a new
strategy of the total pollutant load control system with a target year 2009. The committee
reviewed compliance with the 5th total pollutant control system and current status of water
environment in each sea area. They also examined water pollution mechanism such as
internal production of COD as well as purification function of tidal lands. Based on thereport from the expert committee, the Central Environment Council submitted a report to
the Minister of the Environment on May 18, 2005. The following shows the outline of thereport which shows future direction and challenges of the 6th pollutant load control program.
Introduction
The area-wide total pollutant load control system aims to prevent water pollution inextensive enclosed coastal sea areas in which the population and industrial activities arehighly concentrated. The system was introduced in 1978 as a result of the revision of theWater Pollution Control Law and the Law Concerning Special Measures for Conservationof the Environment of Seto Inland Sea.
The specified sea areas that come under the area-wide total pollutant load control system
are the Tokyo Bay, the Ise Bay and the Set Inland Sea. The specified land areas subject
to control are catchment basins in 20 prefectures including the Tokyo Metropolis and thespecified items are the chemical oxygen demand (hereinafter referred to as COD), nitrogenand phosphorus.
Under the area-wide total pollutant load control system, the Minister of the Environment
decides on a basic policy for total pollutant load reduction in each specified sea area, indicating
the target year and the target amount of pollutant load to be reduced in each source category
and in each prefecture. Based on the basic policy, the governor of each prefecture develops
a total pollutant load reduction plan aiming to reach its target amount of reduction.
Concrete means to reach the target amount of reduction include 1) development of household
sewage treatment facilities, 2) the application of total amount control standards to industrial
wastewater (50m3 or more per day on an average), and 3) the provision of guidance forsmall scale and non-controlled industries and, farmers, stock raisers.
A target amount of reduction is to be established within practicable limits, with mattersas population and industrial trends, the technical level of sewage treatment, and expected
progress of sewer system construction taken into account.
The 1st to the 4th total pollutant load control programs, which set COD as a specified item,
were implemented with 1984, 1989, 1994 and 1999 as the respective target years. As aresult, the COD load in each specified basin was steadily reduced. As a result of the reduction− 93 −

Chapter6 APPENDIX
of COD load, water quality was improved in some sea areas but the situation was far fromreaching the Environmental Quality Standard (hereinafter referred to as EQS) of COD andthere arises eutrophication gave rise to environmental problems such as red tide and oxygendeficient water mass.
Thus, starting from the 5th area-wide total pollutant load control program for 2004 as its
target year, nitrogen and phosphorus, which are causal elements for internal production of
COD (organic pollution resulted from multiplication of phytoplankton), were added to thespecified items for further improvement of COD and the prevention of eutrophication in
the specified sea areas.
1. Trends of Water Pollutant Loads in Specified Basin(1) COD Loads
The COD loads in 1979, the starting year of area-wide total pollutant load control system,
were 477 tons/day in the Tokyo Bay, 307 tons/day in the Ise Bay and 1,012 tons/day in
the Seto Inland Sea. The promotion of pollutant load control measures is expected todecrease them to 228 tons/day, 203 tons/day and 630 tons/day respectively by 2004, theyear targeted by the basic policy on the 5th total pollutant load control program. The ratiosof reduction in a period between 1979 and 2004 come to 52%, 34% and 38% respectively
for the Tokyo Bay, the Ise Bay and the Seto Inland Sea.
(2) Nitrogen and Phosphorus Loads
In 1999, the nitrogen loads amounted to 254 tons/day in The Tokyo Bay, 143 tons/day in
the Ise Bay and 596 tons/day in the Seto Inland Sea. These were intended to be reduced
to 249 tons/day, 137 tons/day and 564 tons/day respectively by 2004, representing reduction
ratios of 2%, 4% and 5% in a period from 1999 to 2004.
The phosphorus loads in 1999, which were 21.1 tons/day in the Tokyo Bay, 15.2 tons/dayin the Ise Bay and 40.4 tons/day in the Seto Inland Sea, were aimed to be decreased to19.2 tons/day, 14.0 tons/day and 38.1 tons/day respectively by 2004. The aimed decreases
represent 9% for the Tokyo Bay, 8% for the Ise Bay and 6% for the Seto Inland Sea ina period from 1999 to 2004.
In the prefectures concerned, the pollutant loads of nitrogen and phosphorus had been
estimated before these two substances were added to the specified items under the area-wide
total pollutant load control system. The nitrogen loads thus estimated for 1979 amounted
to 364 tons/day in the Tokyo Bay, 188 tons/day in the Ise Bay and 666 tons/day in the
Seto Inland Sea and those of phosphorus were 41.2 tons/day, 24.4 tons/day and 62.91 tons
/day respectively. When the pollutant loads of nitrogen and phosphorus in 1979 are comparedto the reduction targets for 2004 for reference' sake, expected decreases in nitrogen andphosphorus loads would be respectively by 32% and 53% in the Tokyo, 27% and 43% in
the Ise Bay, and 15% and 39% in the Seto Inland Sea.
2. Measures to Reduce Total Pollutant Loads(1) Measures to Reduce Household Pollutant Load
Between 1979 and 1999, the populations in the specified basins increased by 16% in theTokyo Bay region, by 15% in the Ise Bay region and by 7% in the Seto Inland Sea region,
their populations being about 26 millions, 11 millions and 30 millions in 1999. The specified
basins covering less than 20% of the gross land area of Japan have more than 50% of its
total population.
In the specified basins with increasing populations, wastewater treatment facilities such as
sewers and household sewage treatment tanks have been developed and/or improved toreduce the household pollutant load, resulting in a rise of household sewage treatment ratios,that is, an increase from 48% in 1979 to 87% in 1999 in the Tokyo Bay region, from 30%
to 59% in the Ise Bay region and from 35% to 67% in the Seto Inland Sea region.

− 94 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

In sewer systems in the specified basin, advanced treatment (including that for COD) is
progressing steadily and the penetration rates among their populations increased from 4.5%
in 1999 to 8.5% in 2003 in the Tokyo Bay region, from 9.9% to 22.2% in the Ise Bay region
and from 14.1% to 24.2% in the Seto Inland Sea region. Combined sewer system is being
improved in order to reduce the load of pollutants overflowed with rainfall from the
combined sewer system.
(2) Measures to Reduce Industrial Pollutant Loads
To decrease the industrial pollutant load, as well as the area-wide total water pollutant
control programs carried out for quite a long time, the national government set the effluent
standards in terms of nitrogen and phosphorus, the local governments gave guidance for
reduction, and factories also addressed the problem independently.
Generally, industrial wastewater is treated by a biological treatment, coagulation, filtrationor combinations of them. In addition to the above treatment methods, some of large-scaleindustries employ such measures to reduce COD as incineration of thick liquid-waste, oxygen
aeration of active sludge, chemical oxidization; and for the reduction of nitrogen, incinerationof thick liquid-waste, biological denitrification, ammonium stripping, and nitric acid collection
by means of membrane. As for phosphorus, coagulation treatment is commonly used.
As for small-scale industries that are not subject to the regulation, local governments set
more stringent effluent standards and/or other effluent standard by their ordinances, andprovide them with guidance in reducing pollutant loads.
(3) Measures to Reduce Other Pollutant Loads
Since 1992, Environmentally-Friendly Farming has been built up across Japan. The Law
for Promoting the Introduction of Sustainable Agricultural Production
Practices was enacted in 1999, and it gives farmers incentives to make efforts to reducethe consumption of chemical fertilizer by tax favors and financial supports. To optimize
the use of fertilizer, the fertilizing standards have been reviewed by the prefectures andtechnology contributing to the reduction in the consumption of fertilizer is being introduced.
In the field of livestock farming, the Law concerning the Appropriate Treatment and Promotionof Utilization of Livestock Manure was enacted in 1999 and put in full effect in 2004. The
Law set management standards of livestock feces to be applied to stock raisers above acertain scale. In this connection, facilities needed for proper management of livestock feces
such as compost sheds and wastewater treatment facilities have been developed.
As for fish-farming, the Law to Ensure Sustainable Aquaculture Production was enacted in
1999. In accord with the Law, fisheries cooperative associations formulate a plan to improve
environment in farm-fishing field. Standards for developing and popularizing formula feedthat can keep pollutant loading on a farm-fishing field as low as possible are set forth andthe development of an efficient feeding system to minimize residual feed are in progress.
(4) Measures to Conserve and Restore Tidal Wetlands
Tidal wetlands function to purify water, maintain biological diversity and provide people
with opportunities to be in contact with nature. On the coastal zones of the specified sea
areas, reclamation was abundant mainly in the period of high economic growth in order tosecure land for industrial use and port development, resulting in quick disappearance oftidal wetlands. So as to restore such lost tidal wetlands in coastal zones, tidal wetland
restoration projects are being promoted in the specified sea areas.
3. Current Status of Water Environment in Specified Sea Areas(1) Trend of Water Quality (COD, Nitrogen and Phosphorus)
Among the specified sea areas, the Tokyo Bay has the highest level of COD, followed by− 95 −

Chapter6 APPENDIX
the Osaka Bay, the Ise Bay and the Seto Inland Sea (excluding the Osaka Bay). In the
period from 1981 to 2003, COD tended to fall in the Tokyo Bay and the Osaka Bay. Although
it is not certain whether the same applies to the Ise Bay and the Seto Inland Sea (excluding
the Osaka Bay), the Ise Bay (excluding the Mikawa Bay) and the Seto Inland Sea haveshown a slight decrease in COD since 1989 or so when their data are corrected by reducing
recent COD increments in the Pacific coast.
Like COD, the concentrations of nitrogen and phosphorus in the specified sea areas are at
the highest level in the Tokyo Bay, followed by the Osaka Bay, the Ise Bay and the Seto
Inland Sea (excluding the Osaka Bay). From 1981 to 2003, a downward tendency wasobserved in the Tokyo Bay and the Osaka Bay. Although it is not certain whether there
are any decreasing tendency in the Ise Bay and the Seto Inland Sea (excluding the Osaka
Bay) on a long term basis, their concentrations in the Seto Island Sea have fallen slightly
since 1999.
(2) Achievement Ratio of Environmental Quality Standards
The achievement ratios of Environmental Quality Standard (hereinafter referred to as EQS)of COD in the specified sea areas in 2003 amounted to 68.4% in the Tokyo Bay, 50.0% in
the Ise Bay, 66.7% in the Osaka Bay and 70.0% in the Seto Inland Sea (excluding the
Osaka Bay). There was no improvement of EQS achievement ratio between 1981 and 2003
in any of the specified sea areas. As noted above, level of COD has decreased in some ofsea areas but the reduction in level of COD has not led to improvement of EQS achievement
ratios.
In 2003, the EQS achievement ratio of nitrogen and phosphorus were 50.0%, 57.1%, 100%and 96.5% respectively in the Tokyo Bay, the Ise Bay, the Osaka Bay and the Seto Inland
Sea (excluding the Osaka Bay). In Osaka Bay, the EQS achievement ratio of nitrogen andphosphorus reached 100% for the first time in 2003. Nevertheless, preliminary observation
data for 2004 suggested that the EQS achievement ratio in the Osaka Bay would fail tobe met in 2004.
While the EQS achievement ratios between 1999 and 2003 leveled off in the Tokyo Bay, it
was improved from 42.9% to 57.1% in the Ise Bay, from 66.7% to 100% in the Osaka Bay,and from 85.0% to 96.5% in the Seto Inland Sea (excluding the Osaka Bay).
(3) Red Tide
In the Tokyo Bay, the occurrence of red tide changed little in the number between 1979
and 2003, staying around 50 /year. In the Ise Bay, it decreased from 159 in 1979 to about
50/year in 1993 and has been leveling off in recent years. In 1970s, 200 to 300 cases of
red tide occurred in the Seto Inland Sea. However, there is a lowering tendency on a long-termbasis, and the number is remaining to be 100 or so annually in recent years. A comparisonof the ratios of the areas in which red tide occurred to the total areas of the bays andthe seas of the Seto Island Sea in 2000 indicates that it was conspicuously high in the
Osaka Bay.
The Seto Inland Sea, in which fish-farming is one of the major industries, suffers from damages
resulted from red tide. Damage done to fishery by red tide amounted to 39 cases a year
in a peak period but 10 or so in recent years.
(4) Oxygen-Deficient Water Mass
The water mass, which has extremely low level of dissolved oxygen (hereinafter referred
to as DO) and has harmful effects on marine animals, is called oxygen-deficient water mass.
The water in the Tokyo Bay, Ise Bay and Osaka Bay is stratified mainly in summer andoxygen-deficient masses appear in bottom layers. The Ministry of the Environment's investigations
showed that low levels of DO below 3mg/L were observed at a number of measurement
points. Further, investigations by the prefectures concerned and others revealed that large-scale
oxygen-deficient masses stayed for a few months.

− 96 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Such oxygen-deficient masses do harm to living of benthos. For example, according to asurvey on benthos in the Tokyo Bay carried out by the Ministry of the Environment in
2003, DO was low in the center area of the Tokyo Bay in summer and a scarcity ofbenthos both in population size and in the number of species was confirmed. A fall of DO
also causes an increase in the amount of nitrogen and phosphorus liquating from bottom
sludge.
When an oxygen-deficient mass rises to a coastal area due to climatic conditions, it becomesblue tide, which may sometime inflict damage such as annihilation of shellfishes. Compared
to a period around 1985, the occurrence of blue tide has decreased in the Tokyo Bay andthe Ise Bay.
In the Seto Inland Sea (excluding the Osaka Bay), lower DO than 3mg/L was not observedin recent investigations, but occurrence of oxygen-deficient masses was reported in somehighly stagnant sea areas.
4. Water Pollution Mechanism in Specified Sea Areas
An enclosed coastal sea hardly exchanges its seawater for that of the open sea and so
pollutants easily deposit inside the sea area. In summer, stratification develops due to higher
surface temperature and inflow of fresh water from rivers. This prevents the seawater fromvertical mixing and DO in the bottom layer easily fall. Therefore, enclosed coastal sea has
higher COD, nitrogen and phosphorus than those in the open sea, and it is frequently
threatened by such problems as red tide and oxygen-deficient masses.
Major factors affecting water pollution in enclosed coastal seas include the inflow of organic
pollutants and nutritive salts from land areas, inflow of fresh water from rivers, internal
production of organic matters, sedimentation, deposit and decomposition, elution of nutritive
salts from bottom sludge, seawater-exchange with the open sea, and displacement and stirringof seawater by a tidal current. In addition, weather conditions like water temperature andthe amount of solar radiation, animals' food chain, taking up from a sea area by fishing,denitrification under an anaerobic condition and so forth complicate the water pollution
mechanism.
(1) Pollutant Load
The relation between the pollutant load on a unit area of water and the water quality inthe specified sea areas is: In a sea area with a larger pollutant load per unit area of water,
the concentration is higher. In a sea area with a larger amount of reduction in pollutant
load per unit area of water, a downward tendency of the concentration is more apparent.
(2) Internal Production of Organic Matters
The internal production of organic matters resulted from multiplication of phytoplankton is
activated particularly in summer. Therefore, COD in the specified sea areas undergoes aseasonal change to rise in summer. The ratio of contribution of internal production to COD
in a specified sea area (an annual average), calculated by the delta COD method, is about
40% in the Tokyo Bay and the Ise Bay and about 30% in the Seto Inland Sea.
(3) Elution from Bottom Sludge
Nitrogen and phosphorus eluted from bottom sludge influence the water quality of thespecified sea area. The amount of these substances eluted from bottom sludge tends toincrease as the bottom layer becomes anoxic. When nitrogen and phosphorus eluted frombottom sludge are transported to the surface layer by diffusion and mixing, they are
consumed by phytoplankton, leading to internal production of organic matters.
(4) Purification of Water in Tidal wetland
A tidal wetland functions as habitats of a variety of wildlife, namely, benthos, fish, plankton− 97 −

Chapter6 APPENDIX
and birds. Their water is purified as organic matters and nutritive salts are taken into animals
through a food chain. The tidal wetland itself has such water purifying functions as filtration
through its sand and earth layer and denitrification in its reducing layer.
(5) Recovery of Nitrogen and Phosphorus from Sea Area through Fishing Activities
Fishery in the specified sea areas leads to recovery of nitrogen and phosphorus directlyfrom the sea. The pollutant loads of nitrogen and phosphorus recovered through fishingactivities amount to a few percent in the Tokyo Bay and the Ise Bay and to 15% or so in
the Seto Inland Sea of the load of pollutant inflow from land.
(6) Impact of Inflowing Rivers
The inflow of fresh water from rivers affects water exchange with the open sea. In a sea
area in which the ratio of the inflow of fresh water to its capacity is larger, as in thecases of the Tokyo Bay, the Ise Bay and the Osaka Bay, COD in the water area tends todecrease in a period when the inflow of fresh water increases.
(7) COD in the Open Sea
It was found that the levels of COD in Japan's coastal sea areas of the Pacific, which extend
closely along the course of the Japan Current are on a rising trend these years. Such anincrease in COD in the open sea is considered to have influence also on the COD in thespecified sea areas.
(8) Estimated Effect of Reduction in Pollutant Load and Restoration of Tidal wetlands on
Improvement of Water Quality in the Tokyo Bay
A water quality estimation model developed by the National Institute for Environmental
Studies was used to examine the impact of reduction in pollutant load and restoration of
tidal wetlands on the improvement of water quality. Since the new model is of a transient
analysis incorporating the elution of nutritive salts from bottom sludge, the flow rates ofrivers and changes in the load of pollutants from land, all of which are not reproducible
by previous water quality estimation models, it is capable of reproducing the quality ofwater that keeps changing in terms of time and space more in detail.
A simulation study of the Tokyo Bay using this model gave the following results: If theactual pollutant loads in terms of COD, nitrogen and phosphate in 1999 are reduced by,for example, 30%, the concentrations of all the quality items will be reduced throughout
the water area; if, in addition to the reduction in pollutant loads, a tidal wetland covering
an area of about 2,700 ha. is restored in the inner part of the bay, the water quality will
be further improved; and oxygen-deficient masses which form on a large scale mainly insummer will be decreased in their scale by the reduction in the pollutant loads and therestoration of the tidal wetland.
6. Future Direction of the 6th Area-wide Total Pollutant Load Control(1) Need to Improve Water Environment in Specified Sea Areas
In discussing the need of improving water environment in the specified sea areas, the
EQS achievement ratios (COD, nitrogen and phosphorus), which are the benchmarks ofwater environment, will serve as an important index. This may not suffice, however, insome water areas. For instance, if in a sea area, oxygen-deficient masses make the environment
unsuitable for benthos to live, it is a problem requiring close attention.
With low percentages of EQS achievement, the Tokyo Bay, the Ise Bay and the Osaka
Bay are suffering from large-scale oxygen-deficient masses. Further effort to improve thewater environment in these three bays will be necessary.
In the Seto Inland Sea (excluding the Osaka Bay), the EQS achievement ratios in terms of− 98 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

nitrogen and phosphorus have improved to 96.7%, their standard values being almost reached.
As for COD, the improvement of EQS achievement ratio remained unsatisfactory, but thelevel of COD remains lower than in the Tokyo Bay, the Ise Bay and the Osaka Bay. Oxygen-deficientmasses are seen only in limited water areas.
As stated above, the quality of water in the Seto Inland Sea (excluding the Osaka Bay) being
higher than in the other specified sea areas, and in terms of nitrogen and phosphorus, itwill be appropriate to maintain the present levels of nitrogen and phosphorus, both ofwhich almost fulfilled the EQS. With regard to COD, while taking measures required toprevent the present quality level from deteriorating, the quality of water aimed at specificallyfor the Seto Inland Sea should be examined, taking into account the possibility that theproperties of organic pollutants may have changed in a long period of time.
When the conditions of the bays and the seas of the Seto Inland Sea are looked at individually,some of them show a rising tendency of COD in recent years and the appearance of oxygendeficient masses is reported in a few of others. How to cope with these problems requires
continued study.
(2) How Should Countermeasures Be?
As mentioned above, loading of pollutants from land and internal production of organic
substances are major determinants of the quality of water in the specified sea areas. Elution
from bottom sludge and water purification function of tidal wetlands also has effect. These
must be kept in mind in developing new countermeasures.
(a) Reduction of Pollutant Loads
As for the Tokyo Bay, the Ise Bay and the Osaka Bay, of which the water environment
need to be further improved, target amounts of reduction at the 6th area-wide total pollutant
load control program should be decided, considering the contents and the degree of difficultyof the measures so far taken, costs vs. effect, a seasonal change in the removal ratio andso forth, so as to reduce pollutant loads in terms of nitrogen and phosphorus effectively.
As concrete measures, the following should be included. They have to be pushed forwardwith cooperation of the relevant parties and agencies concerned.
- The household pollutant load has been reduced but its percentages in the total pollutant
load are rising as illustrated by 68% in the Tokyo Bay, 53% for the Ise Bay and 68% for
the Osaka Bay in 1999. To deal with this, domestic sewage treatment facilities should befurther improved. In order to reduce the pollution loads in terms of nitrogen and phosphorus,
conventional treatment methods should be replaced by advanced treatment process. For
sewers, advanced treatment facilities should be promoted through economic instruments.
The maintenance of septic tanks should be thoroughly improved.
- The COD load from the industry in the specified area has been reduced considerably by
the 1st to 5th area-wide total water pollutant load control programs. Area-wide total waterpollutant control standards should be newly set considering pollutant load reduction measurespreviously taken by the industries, latest development of treatment technology. As for nitrogenand phosphorus, which were added to the list of specified items from the 5th programand for which the full-scale application of control was started on April 1, 2004, total pollutant
load control- As for industrial sources not subject to the area-wide total pollutant load control including
small factories, following measures should be promoted; Effluent control by fixing affluent
standards by prefectures, guidance for the reduction of pollutant loads, and upgrading thetreatment efficiency with improved sewer systems.

− 99 −

Chapter6 APPENDIX- Environmentally-friendly agriculture will be further promoted, particularly enhancing reasonable
use of fertilizers. Proper management of livestock farming will be promoted under the Law
concerning the Appropriate Treatment and Promotion of Utilization of Livestock Manure,by measures such as promotion of construction of livestock feces treatment facilities.
- As for fish farming, fish farm improvement plan will be promoted under the Law to Ensure
Sustainable Aquaculture Production. Development of mixed feed with lower pollution load
will be also enhanced.
- As for the combined sewer system, following measures will be promoted; promotion ofstormwater reservoirs, construction of stormwater infiltration facilities, enhancement of thecapacity of intercepting sewers, improvement of the weir height of overflow and the installationof screens.
As for the Seto Inland Sea (excluding the Osaka Bay), it is necessary promote measuresfor household waste waters and continue existing measure including industrial wastewater(b) Conservation/Restoration of Tidal wetlands
A number of tidal wetlands with water purifying and other functions have disappeared in
the specified sea areas. It is necessary to preserve remaining tidal wetlands and to restore
lost tidal wetlands need be promoted.
In order to suppress elution of nutritive salts from bottom sludge, measures to improve
bottom materials by removal of bottom sludge or cover sand should be forwarded.
The specified sea areas are dotted with large hollows which are sites where reclamationmaterials were collected. These hollows are one of the factors to cause oxygen-deficientmasses. Therefore, it is believed to be necessary to carry out backfilling in the future
while collecting and evaluating data on the effect of backfill of large hollows on the improvementof water environment in the surrounding sea areas.
Further, seaweed beds which attract various species of wildlife to live or breed should bepreserved and/or restored while investigating and studying their function to purify water.
(c) Target year
The target year of the 6th area-wide total pollutant load control program should be FY2009.
7. Future Challenges
Besides the implementation of the 6th area-wide total pollutant load control program, following
issues should be addressed.
(1) Consideration on the water quality to be targeted
The total COD load has been reduced significantly through the past programs, even though
the population and industrial activities in the relevant coastal areas has increased. Since
the advance of effluent treatment methods focusing on biological treatment considerably
contributes to this achievement, among organic matters flowing into the specified sea areas,
those which are slow in consuming oxygen in the sea areas grow in percentage. Thissuggests the probability that the percentage of organic substances consuming oxygen slowly
may increase among the organic substances in the seawater identified as COD. Knowledge
on such an environmental change in the sea areas needs to be advanced.
While continuing to carry out various measures, the quality of water aimed at for each of
the specified sea areas and how to evaluate it should be discussed by taking environmental
changes in the sea areas and new scientific knowledge into account.

− 100 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA(2) Promotion of Investigations and Research and Examination of Countermeasures
There is a need to promote investigations and research about the mechanism causing waterpollution in an enclosed coastal sea, namely, the impact of nutritive salts, which flow inand out accompanying water exchange with the open sea, on the water quality of thespecified sea areas; the effect of natural or artificial changes of the landforms of the coastal
zones on the movement of seawater in the specified sea areas and their water exchangewith the open sea; as well as loading of pollutants from land and internal production.
Acquired knowledge about these problems should be used in deciding on measures toimprove the water environment in enclosed coastal seas more effectively.
(3) Supply and Diffusion of Information and Public AwarenessPollutant loads in the specified areas are attributed to various entities' social and economic
activities. To reduce them, strenuous effort of all the parties involved is indispensable.
Information on the water environment in the specified sea areas should be provided toand spread among them and they should be enlightened in this regard so that they canadvance viable measures to reduce pollutant loads from their own positions.

Mechanism of the Total Pollutant Load Control System
Basic Policy for Areawide Total pollutant Load Control-Minister of the environment formulates a basic policy
for each specified body of water-The policy includes quantitative reduction targets

Areawide Total pollutant Load reduction Plan
-The governor of each prefecture makes a plan andsubmits it to Minister of the Environment for approval-The plan includes the pollutant load reduction target foreach pollution source and means for achieving the target

Regulation of Pollutant load
through Total Pollutant Load
Control Standards-Factories and other commercial
facilities with effluent volumes of
50m3/day or more are obligatedto comply-Obligation to measure pollutionload(concentration x exhaust
volume)Guidanace for reducing Pollution
Load of Effluents,etc.
-Small commercial facilities-Livestock,fish farming,agriculture-Households,etc.

− 101 −

Project Implementation
・Improvement of sewerage
and johkasou systems
・Advances in household
wastewater treatment
・Others

Chapter6 APPENDIX
6.4 MEASURES TO PREVENT EUTROPHICATION IN ENCLOSEDCOASTAL SEAS
In enclosed coastal seas, such as the inner bay and inner sea, the degradation of water
quality - what we call eutrophication - occurs due to the excessive growth of plankton andalgae, which is caused by nutrients such as nitrogen, phosphorus and so forth, as a result of
human activities. In these sea areas, not only do problems related to environmental conservationarise, including damage to fisheries due to red tide and anoxic water, but the scenic landscapesfor recreation are also destroyed.
To prevent eutrophication in such enclosed coastal seas, the Japanese Ministry of theEnvironment established an environmental standard and water emission standard with respect
to nitrogen and phosphorus in 1993. The water emission standard, concerning nitrogen andphosphorus was based on the Water Pollution Control Law, and applies to those sea areas withenclosed natural habitats above a certain level. Currently, 88 seas, including Tokyo Bay, Ise
Bay and Seto Inland Sea, have been designated as specified locations for water discharge andeffluent regulation was implemented in October, 1993. The enclosed index indicating the degreeof closure can be worked out according to the chart below and those sea areas with an index
higher than 1 are designated as targets for regulation. In addition, the environmental standard
concerning nitrogen and phosphorus was applied to major enclosed coastal seas such as Tokyo
Bay, Ise Bay and the Seto Inland Sea in April 1998, and the Ariake Sea in March 2000.

Explanation of parameters for degrees of closure
Width of Baymouth

The width of the entrance to the sea area：W

Area

The square measure of the Inner section of the sea area：S

Max. Depth of Inner
Section of the Bay

The depth at the deepest part of the sea area：D1

Max. Depth of Baymouth

The depth at the deepest part of the entrance to the sea area：D2

Enclosed Index

A high value indicates a high risk of eutrophication due to thenegative situation of water circulation . According to the Water
Pollution Control Law, sea areas with a value higher than 1 aredesignated as targets of regulation.

Ｓ×Ｄ１
Ｗ×Ｄ２

b

S
W
a

D2

D1

− 102 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA● Environmental Standard Designated Water Area
To prevent the pollution of water for public use, the Ministry of the Environment
establishedan environmental standard with the protection of people's health and the conservation of
their living conditions as the desirable goals of water conservation administration.
Regarding standards related to the conservation of the living environment, rivers, lakes
and seas are classified into various types of water bodies and are set up with various standard
values depending on their various water usages.
Category

Water Usage

pH

Chemical
OxygenDemand(COD)(mg/l)

Standard values
Dissolved
Coliform
Oxygengroup(DO)number(mg/l)(MPN/100ml)

n-hexane extract（oil content etc.）(mg/l)A

Fishery Class1・bathing・conservation ofnatural environment・ 7.8〜8.3
and usages listed in
B- C

2 or less

7.5 or more

Below 1,000

Not detectable

B

Fishery Class2・
industrial water and 7.8〜8.3
all usages listed in C

3 or less5 or more―

Not detectable

C

Conservation ofliving environment

8 or less2 or more――

7.0〜8.3

Remarks : Number of coliform groups shall be less than 70MPN/100ml in oyster cultures for fresh consumption
in fishery class 1 in category A.
（Notes） 1. Conservation of the natural environment conservation of nature and other natural resources.
2. Fishery Class 1 Fishing such as red sea-bream, yellow tail, seaweed (wakame) and that for Fishery
Class 2
Fishery Class 2 Fishing such as gray mullet, seaweed (nori) etc.
3. Conservation of the environment no unpleasant odors at the seaside or beach

Environmental standard related to conservation of the living environment of sea areas
Standard values
Category

Water Usage

Conservation of natural environment andⅡ, Ⅲ, Ⅳ
（except Fishery Class 2 and 3）
Fishery Class 1,Marine recreation/bathing and Ⅲ, Ⅳ
II （except Fishery Class 2 and 3）
Fishery Class 2 and Ⅳ
III （except Fisherｙ Class3）
Fishery Class3, Protection of benthic organisms,
IV industrial water supply
I

Total nitrogen(mg/l)

Total phosphorus(mg/l)

0.2 or less0.02 or less

0.3 or less0.03 or less

0.6 or less0.05 or less1 or less0.09 or less

Notes) 1. Conservation of the natural environment conservation of nature and natural resources
2. Fishery class 1： High variety, stable and well-balanced fishery production is possible, including
benthic fish.
Fishery class 2： High fishery production except for some bottom fish
Fishery class 3： Catches only for pollution-tolerant species
3. Protection of benthic organisms survival of benthic organisms throughout the year

●Area-wide Total Pollutant Load Control Area
An Area-wide Total Pollutant Load Control system has been established to decrease
the amount of pollution load in wide-area enclosed seas. Sea areas that can barely reach or
maintain the environmental standard by controlling the concentration level of the substancesdischarged from factories are designated as targets for this regulation, and the full regulation
for the amount of pollutant load and emissions will be implemented in the factories. The target
areas (designated water bodies) are registered as Area-wide Total Pollutant Load Control Areas.

− 103 −

Chapter6 APPENDIX
6.5 THE SPECIAL LAW FOR THE CONSERVATION OF THE
ENVIRONMENT OF THE SETO INLAND SEA
Law No. 110 of October 2, 1973
Amended by LawNo.35ofMay28,l976,
Law No. 47 ofJune1,1976and
Law No. 68 ofJunel3,1978
ChapterⅠ General Provisions (Article 1〜Article 2)
ChapterⅡ Plan for Conservation of the Environment of the Seto Inland Sea (Article 3〜Article 4-2).
ChapterⅢ Special Measures for Conservation of the Environment of the Seto Inland Sea
Section1 Restriction on the Installation of Specified Facilities, etc. (Article 5〜Article 12-3).
Section2 Prevention of the Occurrence of Damage from the Eutrophication (Article 124〜
Article 12-6).
Section3 Conservation of the Natural Seashore etc. (Article 12-7〜Article 13)
Section4 Promotion of Projects for Conservation of Environment, etc. (Article l4〜Article l9)
Chapter IV Miscellaneous Provisions (Article 20〜Article 23)
ChapterⅤ Penal Provisions (Article 24〜Article 27)
CHAPTER I
GENERAL PROVISIONS(Purpose)
Article 1
The purpose of this Law is to promote the conservation of the environment of the Seto Inland
Sea by stipulating matters necessary for the formulation, etc. of a plan for the conservation of
the environment of the Seto Inland Sea in order to promote the implementation of effective
measures in the conservation of the environment of the Seto Inland Sea and by providing
special measures in connection with restrictions on the installment of specified facilities, preventionof damage from the eutrophication and with the conservation of the natural seashore, etc.
(Definitions)
Article 2
1. The term " Seto Inland Sea" as used in this Law shall mean sea are a enclosed by thestraight lines described herein below the shore lines, and other sea areas designated by
Cabinet Order:(1) Straight lines drawn from Kii Hinomisaki Lighthouse Wakayama Prefecture to Ishima,
Maejima of Tokushima Prefecture and then to Gamoda Misaki of the same prefecture;(2) A straight line drawn from Sata Misaki of Ehime Prefecture to the Sekizaki Lighthousein Oita Prefecture; and(3) A straight line drawn from the Hinoyamashita Light house in Yamaguchi Prefecture to
the Mojizaki Lighthouse in Fukuoka Prefecture.
2. The term "prefectures concerned" shall mean Osaka Prefecture, Hyogo Prefecture, Wakayama
Prefecture, Okayama Prefecture, Hiroshima Prefecture, Yamaguchi Prefecture, Tokushima
Prefecture, Kagawa Prefecture, Ehime Prefecture, Fukuoka Prefecture, Oita Prefecture andother prefectures designated by Cabinet Order being related to the environmental conservationof the Seto Inland Sea.
3. The term "governors of prefectures concerned" shall mean the governors of the prefecturesconcerned.

− 104 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

CHAPTER II
PLAN FOR CONSERVATION OF THE ENVIRONMENT OF THE SETO INLAND SEA(Basic Plan for Conservation of the Environment of the Seto Inland Sea)
Article 3
1. In View of the benefits of the Seto Inland Sea, both as a place of scenic beauty unmatchedby any in the country or elsewhere in the world and as a storehouse of rich fishery resourcesand of the fact that the Seto Inland Sea should rightly be enjoyed equally by all citizens of
the nation and bequeathed to posterity, it be hooves the national government to formulate
basic plan (to be referred to as the "Basic Plan" hereafter in this Chapter) for the conservationof the environment of the Seto Inland Sea in respect of preservation of water quality, conservationof scenic beauty, etc. of the Seto Inland Sea in Order to promote the implementation ofeffective measures.
2. In determining or altering the Basic Plan, the Prime Minister shall in advance hear theopinions of the Seto Inland Sea Environmental Conservation Council and the governors ofprefectures concerned.
3. When the Basic Plan has been determined or altered, the Prime Minister shall, without delay,
send the Basic plan or the change therein to the governors of prefectures concerned and,in addition, publicly announce the same.
(Prefectural Plan for Conservation of the Environment of the Seto Inland Sea)
Article 4
1. The governors of the prefectures concerned shall, on the basis of the Basic Plan, establish
prefectural plan for conservation of the Seto Inland Sea in respect of the measures to be
implemented for the conservation of the environment of the Seto Inland Sea in the area ofthe prefectures concerned (to be referred to as the "Prefectural Plan" hereafter in this chapter)
2. The governors of the prefectures concerned shall, when they intend to establish the PrefecturalPlan, report the content thereof to the Prime Minister in accordance with what is prescribedby Ordinance of the Prime Minister's Office.
3. When the Prime Minister has received the report mentioned in the preceding paragraph, hemay, upon consulting with the heads of the administrative organs concerned, issue necessary
instructions regarding the drafting of the Prefectural Plan concerned.
4. When the governors of the prefectures concerned have established the Prefectural Plan, theyshall, without delay, send it to the municipalities concerned and in addition, publicly announce
the same.
5. The provisions of the preceding three paragraphs shall apply mutatis mutandis to Changes
in the Prefectural Plan.
(Promotion of the Achievement of the Basic Plan and the Prefctural Plan)
Article 4-2
The State and local public bodies shall endeavor to take measures required for achievement of
the Basic Plan and the Prefectural Plan.
CHAPTER III
SPECIAL MEASURES FOR CONSERVATION OF THE ENVIRONMENT OF THE SETO
INLAND SEA
Section 1
Restrictions, etc. on the Installation of Specified Facilities(Permit for the Installation of Specified Facilities)
Article 5
1. When a person who discharges effluents into a public water area [meaning a public waterarea stipulated in Article 2 paragraph the Water Pollution Control Law, Law No. 138 of 1970
; the same hereinafter] from a factory or an establishment in the area of prefectures concerned− 105 −

Chapter6 APPENDIX(excluding areas designated by Cabinet Order ) plans to install a specified facility [meaninga specified facility stipulated in Article 2 paragraph 2 of the same Law but not including a
specified facility installed in a factory or an establishment from which the maximum quantityof effluents (meaning the effluents stipulated in paragraph 3 of the same Article; the same
here in after) discharged per day does not exceed fifty cubic meters or a specified facility
prescribed by Cabinet Order; the same here in after], he shall obtain a permit from thegovernor of the prefecture in accordance with what is prescribed by Ordinance of the Prime
Minister's Office.
2. A person seeking to obtain the permit mentioned in the preceding paragraph shall file withthe governor of the prefecture an application describing matters set for thin the following
sub-paragraphs;(1) Name or appellation and address, and, in the case of a juridical person, the name of its
representative;(2) Appellation of the factory or establishment and its address;(3) Kind of the specified facility;(4) Structure of the specified facility;(5) Method of operation of the specified facility;(6) Method of treatment of sewage or waste liquid (hereinafter referred to as "sewage, etc.")
discharged from the specified facility;(7) Quantity of effluents (including the quantity for each drain age system);(8) State of pollution of the effluents (including state of pollution of effluents by each drainage
system) and such other matters as are stipulated by Ordinance of the Prime Minister's Office.
3. The application referred to in the preceding paragraph shall be; accompanied by a statement
describing matters concerning prior assessment based on the findings of investigation on
the impact which the proposed installation of the specified facility is likely have on theenvironment.
4. Upon receipt of an application for permit referred to in paragraph 1, the governor of theprefecture shall, without delay, make an announcement of an outline thereof and shall makethe statement referred to in the preceding paragraph open to the inspection by the public
for three weeks from the date of such announcement.
5. When the governor of the prefecture has made the announcement referred to in the preceding
paragraph, he shall, without delay, notify the governor(s) of those other prefectures concerned
and the head(s) of those municipalities which are relevant on the ground of environmental
preservation to the proposed installation of the specified facility and shall seek the opinionsof the said governors of the prefectures concerned and the heads of the municipalities, fixing
a period for their reply.
6. When the announcement referred to in paragraph 4 is made, any person who has interestin the proposed installation of the specified facility may file with the said governor of theprefecture a statement of opinion on matters regarding the prior assessment referred to inparagraph 3 any time up to the last day of the period for public inspection referred to inparagraph4 hereof.
7. Matters to be dealt with in the statement of prior assessment referred to in paragraph 3
shall be prescribed by Ordinance of the Prime Minister's Office.
(Criteria for Permitting the Installation of Specified Facilities)
Article 6
1. The governor of the prefecture shall not issue the permit referred to in paragraph 1 of thepreceding Article unless he finds that the proposed installation of the specified facility
covered by an application filed under the provisions of said paragraph meets either of thefollowing conditions:(1) That the proposed facility is concerning a factory or establishment the purpose of whichis to treat waste;− 106 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

or(2) That the sewage, etc. discharged from the proposed facility present no serious hindrance
to the conservation of the environment of the Seto Inland Sea.
2. Even when the specified facility covered by an application for permit filed under the provisionof paragraph 1 of the preceding Article meets the condition set forth in sub-paragraph (1)of the preceding paragraph, the governor of the prefecture shall take into account the impact
which the installation of such specified facility may have on the environment in relation to
the permit referred to in paragraph 1 of the preceding Article.
(Transitory Measures Relating to Specified Facilities)
Article 7
1. A person who has a facility in the area designated by Article 5 paragraph 1 (including
persons who are in the process of installing a facility) at the time the facility is designatedas a specified facility and who discharges effluents shall be deemed to have obtained thepermit referred to in said paragraph with respect to the facility.
2. Persons who are deemed to have obtained the permit referred to in Article 5 paragraph 1
under the provision of the preceding paragraph shall file with the governor of the prefecture
concerned a notification of the matters referred to in the sub-paragraphs of paragraph 2 ofthe same Article in accordance with the provisions of Ordinance of the Prime Minister's
Office within thirty days from the date on which such facility was designated as a specified
facility.
(Changes in the Structure, etc. of Specified Facilities)
Article 8
1. A person who has obtained the permit referred to in Article 5 paragraph 1 shall obtain apermit before he effects any change in the matters set forth in sub-paragraphs (4) through(7) inclusive of paragraph 1 of the same Article covered by such permit from the governorof the prefecture in accordance with the provisions of Ordinance of the Prime Minister's
Office. This shall not apply to such minor changes as defined by Ordinance of the Prime
Minister Office.
2. Any person who seeks to obtain the permit referred to in the preceding paragraph shall filewith the governor of the prefecture an application stating the matters prescribed in Ordinanceof the Prime Minister's Office.
3. The provisions of paragraph 3 to paragraph 7 inclusive of Article: 5 shall apply mutatis
mutandis to an application for the permit mentioned in paragraph 1 of this Article (excluding
those application prescribed by Ordinance of the Prime Minister's Office) and provisions ofArticle 6 shall apply mutatis mutandis to an application for the permit mentioned in thesame paragraph.
4. When a person who obtained the permit referred to in Article 5 paragraph 1 has effectedany minor change defined by the Ordinance of the Prime Minister's Office referred to in
the proviso of paragraph 1, the person shall file a notification of such effect with the governorof the prefecture within thirty days from the date of such change.
(Changes in Name, etc.)
Article 9
When a person who obtained the permit referred to in Article 5 paragraph 1 has effected anychange in the matters set forth in sub-paragraphs (1), (2) or (8) of paragraph 2 of the same
Article, or when a person has discontinued the use of a specified facility covered by a permit,
such person shall file a notification of such effect with the governor of the prefecture within
thirty days from the date of such change.

− 107 −

Chapter6 APPENDIX(Succession)
Article 10
1. A person who takes over or rents the specified facility covered by the permit referred toin Article 5 paragraph 1 from the person who has obtained such permit shall succeed tothe status of such person with respect to the specified facility.
2. When inheritance or merger takes place in respect of a person who obtained the permit
referred to in Article 5 paragraph 1, the successor or the juridical person which continues
to exist after the merger or which is for med as a result of the merger shall succeed tothe status of such person.
3. A person who has succeeded to the status of the person who obtained the permit referred
to in Article 5 paragraph 1 under the provisions of the preceding two paragraphs shall filea notification of such effect with the governor of the prefecture within thirty days from thedate of such succession.
(Order of Measures against Contravention)
Article 11
In the event that any person has installed a specified facility in contravention of the provisionsof Article 5 paragraph 1, or that any person has effected any change in matters prescribed in
Article 8 paragraph 1, in contravention of the provisions thereof, the governor of the prefecture
may order the person to remove or discontinue the operation of the facility or take such othermeasures as may be necessary to remedy the situation caused by such contravention.
(Application of the Water Pollution Control Law, etc.)
Article 12
1. The provisions of Article 5 to Article 10 inclusive, Article 11 Paragraph 1 to paragraph 3
inclusive and Article 23 paragraph 3 to Paragraph 5 inclusive of the Water Pollution Control
Law (only those parts of these provisions which are related to Articles 5, 7, 8, 8-2,10 and 11of the same Law), and those of Article 37 paragraph 1 of the Law relating to the Preventionof Marine Pollution and Maritime Disaster(Law No. 136 of 1970) shall not apply to thespecified facilities installed in factories or establishments located in the area designated in
Article 5 paragraph 1.
2. With respect to the application of the provisions of Article 22 Paragraph I of the Water
Pollution Control Law to the area designated in Article 5 paragraph 1, the term "this Law"
appearing in the same paragraph shall read "this Law (The special law for the conservationof the environment of the Seto Inland Sea, Law No. 110 of l973)."
3. (omission)
4. (omission)
5. Concerning application of the provisions of Article 12 to Article 19 and paragraph 2 toparagraph 4 of Article 35 of the Law Concerning Special Measures Against Dioxins (limited
to the sections relating to Article 12, Article 14 to Article 16,Article 18 and Article 19 of
the same Law), specified facilities relating to persons discharging effluents from factories or
establishments, in which a specified facility is to be installed, in areas stipulated in Article
5, paragraph 1 shall be regarded as not being target facilities for water quality standards
as stipulated in Article 12, paragraph 1, no.6 of the same Law.
6. Concerning application of the provisions of Article 34, paragraph 1 of the Law Concerning
Special Measures against Dioxins to areas stipulated in Article 5, paragraph 1,the phrase "this Law" in said paragraph shall mean "this law [ including the provisions in Article 5through Article 11 of the The special law for the conservation of the environment of the
Seto Inland Sea (Law No.110 of 1973)] .

− 108 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Article 12-2(omission)(Reduction of Total amount of Pollution Load)
Article 12-3
1. In order to prevent water pollution in terms of chemical oxygen demand in the Seto InlandSea, the Prime Minister shall, in respect of the area stipulated in Article 5 paragraph 1 ,establish the fundamental policy for reduction of area wide total pollutant load mentioned in
Article 4-2 paragraph I of the Water Pollution Control Law relative to the reduction of thetotal amount of pollution load expressed in terms of chemical oxygen demand.
2. As regards the application of the provisions of the Water Pollution Control Law relative tothe fundamental policy for reduction of area wide total pollutant load mentioned in the preceding
paragraph and the reduction of the total amount of pollution load on the basis of the same
policy, the parts of the provisions of the same Law which read "Pollution Load", "Specified
Water Areas", "Specified Items" and "Specified Regions" shall read" pollution load expressedin terms of chemical oxygen demand", "Seto Inland Sea as stipulated in Article 2 paragraph
1 of the The special law for the conservation of the environment of the Seto Inland Sea","chemical oxygen demand" and "area stipulated in Article 5 paragraph 1 of the The special
law for the conservation of the environment of the Seto Inland Sea", respectively.
Section 2
Prevention of the Occurrence of Damage from Eutrophication(Guideline for Reduction of Specified Substances)
Article 12-4
1. When the Director General of the Environment Agency deems it necessary for the preventionof the occurrence of damage to the living environment by eutrophication in the Seto InlandSea, he may, in accordance with what is prescribed by Cabinet Order, instruct the governorsof the prefectures concerned to establish a guideline for reduction of specified substances(referred to as the "guideline" hereafter in this Section) relative to the reduction of phosphorus
and other substances specified by Cabinet Order(referred to as("specified substances" hereafterin this Section) discharged into the public water areas in the area stipulated in Article
5 paragraph 1, indicating the reduction target, the target fiscal year and other necessary
matters.
2. In the guideline, there shall be stipulated the policy for guidance relative to reduction of thespecified substances and other matters for the purpose of realizing the aim of attaining the
reduction target in the target fiscal year.
3. When the governors of the prefectures concerned intend to establish a guideline or make achange in the same, they shall, in accordance with what is prescribed by Ordinance of thePrime Minister's Office, report to the Director General of the Environment Agency on thematters mentioned in the preceding paragraph.
4. When the governors of the prefectures concerned have established a guideline or made achange in the same, they shall publicly announce the guidelines or the change therein.
(Guidance, etc.)
Article 12-5
The governors of prefectures concerned may, in accordance with the guideline, give a person
who discharges a specified substance into a public water area in the area stipulated in Article
5 paragraph 1, any guidance, advice or recommendation which may be required.
(Collection of Reports)
Article 12-6
The governors of prefectures concerned may, when he deems it necessary for giving guidance,
advice or recommendation under the preceding Article, request a person who, in connection− 109 −

Chapter6 APPENDIX
with his business activities, discharges a specified substance into a public water area in thearea stipulated in Article 5 paragraph1, and who is designated by Cabinet Order, to submit areport on his method of treating sewage or waste liquid and any other necessary matters.
Section 3
Conservation of the Natural Seashore, etc.
(Designation of Natural Seashore Conservation Areas)
Article 12-7
The prefectures concerned may, in accordance with what is prescribed by an ordinance,
designated as a natural seashore conservation area those parts of the seashore and its adjacentsea areas of the Seto Inland Sea which fall under either of the following subparagraphs;(1) Those parts where sand beaches, reefs or other similar natural conditions are maintainednear the water-boundary line.
(2) Those parts which are used by the public for sea bathing, gathering sea shells and othersimilar purposes and which hare recognized as being suitable for such use both at present
and in the future.
(Notification of Acts, etc.)
Article 12-8
The prefectures concerned may, in accordance with what is prescribed by an ordinance, requirea person who intends to build a new structure, change the form or nature of the land, mine
minerals, quarry stones or conduct other acts in a natural seashore conservation area to submit
a notification and may give a person who submitted such a notification any recommendation
or advice necessary to assure the conservation and proper utilization of the natural seashore
conservation area.
(Special Consideration Given to Reclamation, etc.)
Article 13
1. In considering the license referred to in Article 2 paragraph 1 of the Public Water Body
Reclamation Law (Law No. 57 of l92l) or the approval referred to in Article 42 paragraph
1 of the same Law for projects undertaken in the Seto Inland Sea, the governor of theprefecture concerned shall take into account the peculiarities of the Seto Inland Sea referred
to in Article3 paragraph I hereof.
2. The basic policy of the application of the provision of the preceding paragraph shall be
studied and considered by the Seto Inland Sea Environmental Conservation Council.
Section 4
Promotion of Projects for Conservation of Environment, etc.
(Construction of Sewerage Works and Waste Disposal Facilities, etc.)
Article 14
In view of the current state of water pollution of the Seto Inland Sea, the State and the local
public bodies shall make endeavors to promote the construction of sewerage works and waste
disposal facilities, the dredging of bottom deposit, the installation of facilities and equipments
for monitoring and measuring the water quality, and other projects necessary for the conservationof water quality in the Seto Inland Sea.
(Financial Assistance, etc.) A
Article 15
The State shall make endeavors to extend financial assistance to, arrange loans of necessary
funds for and make other forms of assistance available to, those who undertake the projects
referred to in the preceding Article.

− 110 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA(Formulation of Plans for Projects Designed to Purify the Seto Inland Sea)
Article 16
The national government shall make endeavors for the formulation of plans for large-scale
projects designed to purify the polluted water of the Seto Inland Sea and in this regards shallpromote the development of the technology, etc. necessary for such projects and take necessaryfinancial measures.
(Prevention, etc. of the Spillage of Oil through Marine Disaster)
Article 17
In order to prevent the pollution of the Seto Inland Sea by Oil, the national government shall,in connection with the prevention of the spillage of large volumes of oil through marine disasterand the elimination of spilled oil, make efforts to strengthen its guidance and control, organizea system for the elimination of spilled oil and take any other necessary measures.
(Promotion for the Development of Technology, etc.)
Article l8
The national government shall promptly make efforts to clarify the mechanism by which redtides occur and to develop technology for the prevention and elimination thereof and also makeefforts to develop technology for treatment of oil in ships and other technology for the conservationof the environment of the Seto Inland Sea, and shall take necessary measures based on the
result of such technological development.
(Relief for Persons Engaged in Fishery Suffering Damage Caused by Red Tides, etc.)
Article l9
In view of the large number of instances of fishery damage caused by red tides and oil spillage
in the Seto Inland Sea, the national government shall promptly take necessary measures forthe relief for persons engaged in fishery who are suffering such fishery damage.
CHAPTER IVMISCELLANEOUS PROVISIONS(Recommendations or Advice)
Article 20
1. The Director General of the Environment Agency may, when he finds it necessary for ensuring
proper and smooth implementation of this Law, give the governors of the prefecturesconcerned necessary recommendation or advice.
2. The Director General of the Environment Agency may request the governors of prefecturesconcerned to submit a report on the measures taken in compliance with the recommendation
given to them under the provision of the preceding paragraph.
(Transitory Measures)
Article 2l
In case that an order under the provisions of this Law is established, amended or repealed,certain transitory measures (including those relating to penal provisions) may be prescribed in
the order to the extent that it is judged to be reasonably necessary for the provisions established,amended or repealed thereby(Delegation of Administrative Services, etc.)
Article 22
1. The administrative services which come under the authority of the governors of the prefecture
under this Law may be delegated, in accordance with what is prescribed by Cabinet Order,
to the mayors of cities designated by Cabinet Order.
2. The mayors of cities designated by the Cabinet Order mentioned in the preceding paragraph− 111 −

Chapter6 APPENDIX
shall notify the governor of the prefecture of such matters necessary for the implementationof this Law as are stipulated by Ordinance of the Prime Minister's Office.
(The Seto Inland Sea Environmental Conservation Council)
Article 23
1. The Seto Inland Sea Environmental Conservation Council shall be established within theEnvironment Agency (here in after referred to as "Council").
2. The Council shall study and examine important matters relating to the conservation of theenvironment of the Seto Inland Sea upon request from the Director General of the Environment
Agency or other ministers concerned.
3. The Council may present its opinions to the Director General of the Environment Agency
or other ministers concerned on important matters relating to the conservation of the environmentof the Seto Inland Sea.
4. The Council shall be composed of not more than thirty-four members appointed by the Prime
Minister from among persons of learning and experience.
5. In addition to the matters referred to in the preceding two paragraphs, matters necessary
for the organization and operation of the Council shall be prescribed by Cabinet Order.
6. (omission)
CHAPTER VPENAL PROVISIONS
Article 24
Any person who falls under the following sub-paragraphs shall be imprisoned not more than
one year or fined not more than five hundred thousand yen(￥500,000):(1) Any person who violates the provision of Article5 paragraph1 or Article 8 paragraph 1;(2) Any person who contravenes an order issued under the provision of Article 11.
Article 25
Any person who falls under either of the following subparagraphs shall be punished with a finenot more than one hundred thousand yen(￥100,000):(1) Any person who fails to file the notification mentioned in Article 7 paragraph 2, or who
files a false notification under the same paragraph.
(2) Any person who fails to submit the report mentioned in Article I2-5 paragraph 1, or who
submits a false report under the same paragraph.
Article 26
When the representative of any juridical person, or an agent, servant or any other employee
of a juridical person or a person commits an unlawful act referred to in the preceding two
Articles with respect to the business of such juridical person or person, the person who
committed the act shall be punished, and in addition, the juridical person or person shall be
imposed with a punishment.
Article 27
Any person who fails to file the notification referred to in Article 8 paragraph 4, Article9 or
Article 10 paragraph 3 hereof or who files false notification shall be fined not more than one
hundred thousand yen (￥100,000).
SUPPLEMENTARY PROVISIONS(Excerpts)(Date of Enforcement)
Article 1
This Law shall be enforced on the day immediately following the expiration of one month fromthe Date of its promulgation(October 2, l973).

− 112 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA(Transitory Measures)
Article 2
1. In an area referred to in Article 5 paragraph 1 prior to the enforcement of this Law, any
person who has filed a notification under the provision of Article 5 of the Water Pollution
Control Law with respect to a specified facility and who is not subject to regulation imposed
under the provisions of Article 9 of said Law at the time Law is enforced and who has filed
a notification under the provisions of Article 6 of said Law shall be considered as having
obtained the permit referred to in Article 5 paragraph I with respect to such specified
facility.
2. In an area referred to in Article 5 paragraph 1 hereof, at the time this Law is enforced withrespect to a specified facility any person who is subject to regulation under the provisionsof Article 9 of the Water Pollution Control Law the provisions of Article 5 paragraph 1,
Article 8 paragraph 1 and Article 12 paragraph 1 shall not apply to such person while such
person is subject to such regulation.
3. If any person referred to in the preceding paragraph becomes no longer subject to regulation
under the provisions of Article 9 of the Water Pollution Control Law, such person shall beconsidered as having obtained the permit referred to in Article 5 paragraph 1 or Article 8paragraph 1 with respect to such specified facility.
4.〜 7. (omission)
Article 3
Application of penal provisions to acts done prior to the enforcement of this Law and to thosedone after the enforcement of this Law with respect to an order issued under the provisionof Article 8 of the Water Pollution Control Law or the regulation imposed under the provisionof Article 9 paragraph I thereof shall be as here to fore.
SUPPLEMENTARY PROVISIONS(Excerpts from Law No. 68 of June l3, 1978)(Date of Enforcement)
Article 1
The date of enforcement of this Law shall be the day prescribed by Cabinet Order within one
year of the promulgation of this Law. However, the revisional provisions in Article 1 which
delete Article 4 and Article 5 of the Supplementary Provisions from the Interim Law forConservation of the Environment of the Seto Inland Sea (passage omitted) shall been forced fromthe day of promultation.
(Transitory Measures)
Article 2
The basic plan for the conservation of the environment of the Seto Inland Sea established inaccordance with the provisions of Article 3 of the Interim Law for Conservation of the Environmentof the Seto Inland Sea (referred to hereinafter as the "Interim Law") before revision shall bedeemed to have been established in accordance with the provisions of Article 3 of the The
special law for the conservation of the environment of the Seto Inland Sea (referred to hereinafteras the "Special Measures Law") after revision.

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Chapter6 APPENDIX
6.6 BASIC ACT ON OCEAN POLICY (ACT No. 33 of APRIL 27, 2007)
by CABINET SECRETARIAT of Japan
Table of contents
Chapter I General Provisions (Art.1-15)
Chapter II Basic Plan on Ocean Policy (Art.16)
Chapter III Basic Measures (Art.17-28)
Chapter IV Headquarters for Ocean Policy (Art.29-38)
Supplementary Provisions
Chapter I General Provisions
Article 1 (Purpose)
The purpose of this Act is, with regard to the oceans, to stipulate the basic principles, toclarify the responsibilities of the State, the local governments, business operators and the citizens
as well as to formulate the basic plan with regard to the oceans and other basic matters withregard to the measures on the oceans, by establishing the Headquarters for Ocean Policy inorder to promote measures with regard to the oceans comprehensively and systematically,
through contributing to the sound development of the economy and society of our State andto improve the stability of the lives of citizenry as well as to contribute to the coexistence ofthe oceans and mankind, in consideration of the fact that the oceans, occupying broad portionof the globe, are indispensable factors for maintaining the lives of the living beings including
mankind, and the fact that it is important to realize a new oceanic State in harmonization of
the peaceful and positive development and use of the oceans with the conservation of themarine environment, under the international cooperation, as our State surrounded by the oceans,
based on the United Nations Convention on the Law of the Sea and other international agreements
as well as on the international efforts on the realization of the sustainable development anduse of the oceans.
Article 2 (Harmonization of the Development and Use of the Oceans with the Conservationof Marine Environment)
With regard to the oceans, in consideration of the fact that the development and use of theoceans are the basis of existence for the economy and society of our State, and that securing
the marine biological diversity and conserving other better marine environment are the basisof the existence of mankind and also indispensable for prosperous and affluent lives of thecitizenry, the positive development and use of the oceans shall be executed, aiming at allowing
for the sustainable development and use of the oceans with conservation of marine environment
in order to enjoy the benefit of the oceans in the future.

Article 3 (Securing the Safety and Security on the Oceans)With regard to the oceans, in consideration of the fact that securing the safety and security
on the oceans is important for our State surrounded by the oceans, efforts to secure the safety
and security of the oceans shall be positively promoted.
Article 4 (Improvement of Scientific Knowledge of the Oceans)
In consideration of the fact that scientific knowledge of the oceans is indispensable for the properdevelopment and use of the oceans and conservation of the marine environment, while many
scientifically unsolved fields remain with regard to the oceans, the scientific knowledge of theoceans shall be improved.
Article 5 (Sound Development of Ocean Industries)
With regard to the industries bearing the development, use and conservation of the oceans− 114 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA(hereinafter referred to as "Ocean Industries"), in consideration of the fact that they are thebasis for the sound development of the economy and society of our State and of stabilizationand improvement of the lives of the citizenry, their sound development shall be promoted.
Article 6 (Comprehensive Governance of the Oceans)
Governance of the oceans shall be executed comprehensively and integrally with respect tothe development, use and conservation of the oceans, in consideration of the fact that the matterswith regard to ocean resources, marine environment, maritime traffic and the safety and securityof the oceans interrelate closely with each other, and such matters shall be examined as awhole.
Article 7 (International Partnership with regard to the Oceans)
In consideration of the fact that the oceans are the common heritages of mankind, and thatthe economy and society of our State have been conducted in close international interdependent
relationship, promotion of measures with regard to the oceans shall be executed under theinternational partnership, aiming at bearing the leading role for the formation and developmentof the international order.
Article 8 (Responsibilities of the State)
The State shall be responsible for comprehensively and systematically formulating and implementing
measures with regard to the oceans, in conformity with the basic principle prescribed in Article
2 to the preceding article inclusive(hereinafter refer to as "basic principle").
Article 9 (Responsibilities of the Local Governments)
Based on an appropriate sharing role with the State, the Local Governments shall be responsible
for formulating and implementing the measures that suit the natural and social conditions of
their districts with regard to the oceans, in conformity with the basic principle.
Article 10 (Responsibilities of Business Operators)
The business operators of Ocean Industries shall endeavor to conduct their business, pursuant
to the basic principles, and to cooperate with the State and the Local Governments in implementing
measures with regard to the oceans.
Article 11 (Responsibilities of Citizens)
Citizens, in recognition of the benefit of the oceans, shall endeavor to cooperate with the Stateand the Local Governments in implementing measures with regard to the oceans.
Article 12 (Coordination and Cooperation among the Relevant Parties)
The State, the Local Governments, business operators of Ocean Industries and other relevant
parties, including organizations executing activities with regard to the oceans, shall endeavor tocooperate in mutual communication, in order to realize the basic principles.
Article 13 (Events of the Ocean Day)
The State and the local governments shall endeavor, on the Ocean Day as stipulated in Article
2 of the National Holidays Act (Act No. 178 of 1948), to hold the events that enable the citizens to have better understanding and deeper interests of the oceans.
Article 14 (Legislative Measures, etc.)
The Government shall take necessary legislative, fiscal or financial measures, and other measuresin order to implement measures with regard to the oceans.

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Chapter6 APPENDIX
Article 15 (Preparation of the Documents and Publicizing)
The Government shall prepare documents on the situation of the oceans and the implemented
measures by the Government with regard to the oceans, and shall publicize them in an
appropriate way as needed.
Chapter II Basic Plan on Ocean Policy
Article 16(1) The Government shall formulate a basic plan with regard to the oceans (hereinafter referred
to as "Basic Plan on Ocean Policy"), in order to promote measures with regard to the oceanscomprehensively and systematically.
(2) The Basic Plan on Ocean Policy shall prescribe the following matters:(i) The basic policy of measures with regard to the oceans(ii) The measures that the Government shall implement with regard to the oceans comprehensively
and systematically(iii) In addition to what are listed in the preceding two items, any items necessary for promoting
measures with regard to the oceans comprehensively and systematically(3) The Prime Minister shall seek a cabinet decision on the draft of the Basic Plan on Ocean
Policy.
(4) When the cabinet decision prescribed in the preceding paragraph has been made, Prime
Minister shall publicize the Basic Plan on Ocean Policy without delay.
(5) Bearing in mind the changes on the situation with regard to the oceans, as well as basedon an evaluation of the effect of measures with regard to the oceans, the Government shallreview the Basic Plan on Ocean Policy almost every five years, and shall make necessarychanges.
(6) The provisions of paragraph 3 and paragraph 4 shall apply mutates mutandis to makechanges to the Basic Plan on Ocean Policy.
(7) The Government shall endeavor to take necessary measures for the smooth implementationof the Basic Plan on Ocean Policy by, for example, appropriating its budget each fiscal year,
to the extent permitted by the State's finances, in order to secure funds necessary to ensure
payment of the expenses required for the implementation of the plan.
Chapter III Basic Measures
Article 17 (Promotion of Development and Use of Ocean Resources)
The State shall take necessary measures on conservation and management of living aquatic
resources, conservation and improvement of the growing environment for aquatic plants andanimals, increase of the fishing ground productivity, promotion of the development and use of
petroleum, inflammable natural gas, other mineral resource including manganese ores, cobalt
ores existing on and under the sea floor, establishment of the system for the above mentioned
missions and execution of others, in order to promote the positive development and use of theoceans, considering conservation of the marine environment and to allow for the sustainable
development and use of the ocean resources in the future.
Article 18 (Conservation of Marine Environment, etc.)(1) The State shall take necessary measures to conserve the marine environment including
securing the biodiversity in the oceans with conservation and improvement of the habitat,
reduction of the pollution load caused by water flow into the oceans, prevention of thedischarge of waste materials to the oceans, prompt prevention of the oil spill caused by
accidents of the vessels and others, conservation of the seascape and others, in considerationof the fact that the oceans make a great impact on the conservation of the global environment
such as the prevention of global warming and others.
(2) The State, from the view points of preventing adverse effect on the marine environment,
based on the scientific knowledge, shall execute the measures prescribed in the preceding
paragraph and make efforts to review them properly.

− 116 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

Article 19 (Promotion of Development of Exclusive Economic Zone, etc.)
The State, in consideration of the fact that it is important to strengthen the efforts with regard
to the development, use and conservation and others of the Exclusive Economic Zone and otherareas (the term "the Exclusive Economic Zone and other areas" shall means the Exclusive
Economic Zone defined by Article 1, paragraph 1 of the Law on the Exclusive Economic Zone
and the Continental Shelf (Law No.74 of 1996) and Continental Shelf defined by Article 2 of
the Law. The same shall apply hereinafter)(hereinafter referred to as "Development and othersof the Exclusive Economic Zone and other areas") shall take necessary measures in order topromote the Development and others of the Exclusive Economic Zone and other areas including
the Development and others of the Exclusive Economic Zone and other areas according to thecharacteristics of its sea areas, prevention of the infringement on the sovereign rights of ourState in the Exclusive Economic Zone and other areas and execution of others.
Article 20 (Securing Maritime Transport)
The State shall take necessary measures to secure the efficient and stable maritime transport,
including securing of Japanese vessels, raising and securing seafarers, developing hub ports in
the international maritime transport network and executing others.
Article 21 (Securing the Safety and Security of the Oceans)(1) The State, in consideration of the fact that, for the economy and society of our State,surrounded by the oceans and dependent on import for major portion of the resources, it isessential to secure the development and use of the marine resources, the safety of themaritime transport and others as well as to maintain the order in the oceans, with regard
to the oceans, shall take necessary measures to secure the peace and safety of our State aswell as to secure the maritime safety and public order.
(2) The State shall take necessary measures with regard to the prevention of natural disaster,
prevention of damage expansion in case of occurrence of natural disaster and recovery fromdisaster (hereinafter referred to as "Disaster Prevention"), in order to protect national land
as well as life, body and property of the citizens from disasters such as tsunamis, storm
surges and others.
Article 22 (Promotion of Ocean Survey)(1) The State, in order to formulate and implement the measures with regard to the oceansproperly, shall make efforts to execute the necessary survey including the grasp of theocean situation, the prediction of the change of marine environment and other survey toformulate and implement the measures with regard to the oceans (hereinafter referred toas "Ocean Survey"), as well as to establish systems for monitoring, observing, measuring andother activities necessary to the Ocean Survey.
(2) The State shall make efforts to provide the information obtained by Ocean Survey, in order
to contribute to the formulation and implementation of measures by the Local Governmentswith regard to the oceans as well as to contribute to the activities by the business operatorsand others.
Article 23 (Promotion of Research and Development of Ocean Science and Technology, etc.)
The State, in order to promote the research and development and to disseminate the resultwith regard to the science and technology of the oceans (hereinafter referred to as "Ocean Scienceand Technology), shall take necessary measures including establishing the research systems,
promoting research and development, nurturing researchers and technicians, strengthening
coordination among such research institutions as the State, Incorporated Administrative Agency(referring to the Incorporated Administrative Agency set forth in the Act on General Rules
for Incorporated Administrative Agency (Act No.103 of 1999), Article 2, paragraph 1; the same
shall apply hereinafter), the prefecture, and Local Incorporated Administrative Agency (referring− 117 −

Chapter6 APPENDIX
to the Local Incorporated Administrative Agency set forth in the Act on Local Incorporated
Administrative Agency (Act No.118 of 2003), Article 2, paragraph 1; the same shall apply
hereinafter), universities and private bodies, and executing others.
Article 24 (Promotion of Ocean Industries and Strengthening the International Competitiveness)
The State, in order to promote the Ocean Industries and to strengthen the international
competitiveness, shall take necessary measures with regard to the Ocean Industries, to promote
the cutting-edge research and development, to upgrade the level of technology, to nurture andsecure the human resources and to reinforce the management basis with the improvement ofcompetitive conditions and others as well as to exploit new businesses and to execute others.
Article 25 (Integrated Management of the Coastal Zone)(1) The State shall take necessary measures for the coastal sea areas and land areas, whererecognized suitable for the measures to be implemented in a unified manner upon thenatural and social conditions, to be managed properly, by the regulatory and other measures
to the activities implemented in the integrated manner, in consideration of the fact that
there are difficulties in keeping on enjoying the benefit brought by the resources, naturalenvironment and others of the coastal sea areas in the future only by implementing themeasures with respect to the coastal sea areas when issues in the coastal sea areas are
originated by the activities on land.
(2) The State shall give enough consideration, when executing the measures prescribed in thepreceding paragraph, to securing the protection of the seacoasts from hazards caused bytsunamis, storm surges, high waves and other movement of seawater or ground deformation,and to securing improvement and conservation of the coastal environment as well as topromoting proper use of the seacoasts by the public, in consideration of such fact thatseacoasts have severe natural condition with characteristic landscape, while supporting andraising a great variety of life.
Article 26 (Conservation of the Remote Islands, etc.)
The State, with regard to the remote islands, shall take necessary measures including conserving
the seacoasts and others, securing the safety of navigation as well as establishing the facilities
for the development and use of ocean resources, conserving natural environment in adjacentsea areas, maintaining infrastructure for the life of inhabitant and executing others, in considerationof such fact that the remote islands bear an important role in conserving our territorial sea
and the Exclusive Economic Zone and other areas, and in securing the safety of navigation in
the development and use of ocean resources as well as in conservation of the marine
environment.
Article 27 (Securing International Coordination and Promotion of InternationalCooperation)(1) The State shall take necessary measures to secure the international coordination with regard
to the oceans including subjective involvement in the formation of international agreements
and others with regard to the oceans as well as execution of others.
(2) The State shall take necessary measures, with regard to the oceans, to promote theinternational corporation related to ocean resources, marine environment, Ocean Survey,
Ocean Science and Technology, crime control at sea, Disaster Prevention, maritime rescue
and others, in order to accomplish the role positively in the international society.
Article 28 (Enhancement of Citizen's Understanding of the Oceans, etc.)(1) The State shall take necessary measures, in order that citizens shall have a better understandingof and deeper interests in the oceans, to promote school education and social education withregard to the oceans, propagation and enlightenment of the United Nations Convention on
the Law of the Sea and other international agreements as well as international efforts to− 118 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA

realize the sustainable development and use of the oceans, and popularization of ocean
recreation.
(2) The State shall take necessary measures to promote interdisciplinary education and researchat universities and others, in order to nurture human resources with knowledge and capability
required to meet the political issues appropriately with regard to the oceans.
Chapter IV Headquarters for Ocean Policy
Article 29 (Establishment)
In order to promote measures with regard to the oceans intensively and comprehensively,
Headquarters for Ocean Policy (hereinafter referred to as "the Headquarters") shall be establishedin the Cabinet.
Article 30 (Affairs under the Jurisdiction)
The Headquarters shall take charge of affairs listed in the following items:(i) Matters with regard to drafting and to the promotion of execution of Basic Plan on Ocean
Policy.
(ii) Matters with regard to synthesis coordination of measures of implementation by relevant
administrative bodies based on Basic Plan on Ocean Policy.
(iii) In addition to the tasks referred to in the preceding two Paragraphs, matters with regard
to planning and drafting of important measures with regard to the oceans as well as
synthesis coordination.
Article 31 (Organization)
The Headquarters shall consist of the Director-General of the Headquarters for Ocean Policy,
the Vice Director-Generals of the Headquarters for Ocean Policy, and Members of the Headquarters
for Ocean Policy.
Article 32 (Director-General of the Headquarters for Ocean Policy)(1) The Headquarters shall be headed by the Director-General of the Headquarters for Ocean
Policy (hereinafter referred to as "Director-General"), the post which shall be served as Prime
Minister.
(2) The Director-General shall be in charge of general coordination of the affairs of the Headquarters,
and shall direct and supervise the relevant officials.
Article 33 (Vice Director-General of the Headquarters for Ocean Policy)(1) The Vice Director-General of the Headquarters for Ocean Policy (hereinafter referred to as"Vice Director-General") shall be assigned in the Headquarters, and The Chief Cabinet Secretary
and the Minister for Ocean Policy (the Minister of the State, in charge of assistance to thePrime Minister, with regard to intensive and comprehensive promotion of measures withregard to the oceans upon the direction of the Prime Minister) shall serve as the Vice
Director-General.
(2) The Vice Director-Generals shall assist the duties of the Director-General.
Article 34 (Members of the Headquarters for Ocean Policy)(1) Members of the Headquarters for Ocean Policy (hereinafter referred to as "Members") shallbe assigned in the Headquarters.
(2) The Members shall be assigned with all Ministers of the State other than the DirectorGeneral and Vice Director-General.
Article 35 (Submission of Materials and Other Forms of Cooperation)(1) The Headquarters may, if it considers it necessary for implementing affairs under the jurisdiction,
demand submission of materials, statements of opinions, explanations and other required− 119 −

Chapter6 APPENDIX
cooperation from the heads of the relevant administrative organs, Local Governments,
Incorporated Administrative Agencies and Local Incorporated Administrative Agencies andthe representatives of statutory juridical persons (Corporations which are directly establishedby Acts or juridical persons which are established according to their statute of establishment
provided by special Act, under provision of Paragraph 15 of Article 4 of the Act for Establishmentof the Ministry of Internal Affairs and Communications(Act No. 91 of 1999)).
(2) The Headquarters may also demand required cooperation from parties other than thoseprescribed in the preceding paragraph, if it considers it especially necessary for implementing
affairs under the jurisdiction.
Article 36 (Affairs)
Affairs concerning the Headquarters shall be processed within the Cabinet Secretariat andadministered by the Assistant Chief Cabinet Secretary under commission.
Article 37 (Competent Minister)
The competent Minister as set forth in the Cabinet Act (Act No. 5 of 1947) for the matterspertaining to the Headquarters shall be the Prime Minister.
Article 38 (Delegation to Cabinet Orders)
In addition to what is provided for in this Act, necessary matters concerning the Headquarters
shall be prescribed by a Cabinet Order.
Supplementary Provisions(Effective Date)(1) This Act shall come into effect as from the date specified by a Cabinet Order within aperiod not exceeding three months from the day of promulgation.
(Review)(2) With regard to the Headquarters, comprehensive review shall be executed in five years after
entering into force of this Act, and necessary measures shall be taken based on the resultsof the review.
Note:
This English translation of the Basic Act on Ocean Policy (Effective July 20, 2007) has been
prepared in compliance with the Standard Bilingual Dictionary March 2007 edition. This is anunofficial translation. Only the original Japanese texts of laws and regulations have legal effect,
and the translations are to be used solely as reference material to aid in the understanding ofJapanese laws and regulations.
The Government of Japan shall not be responsible for the accuracy, reliability or currency ofthe legislative material provided in this Website, or for any consequence resulting from use of
the information in this Website. For all purposes of interpreting and applying law to any legal
issue or dispute, users should consult the original Japanese texts published in the Official
Gazette.
http://www.cas.go.jp/jp/seisaku/hourei/data/BAOP.pdf− 120 −ENVIRONMENTAL CONSERVATION OF THE SETO INLAND SEA
Published in January 2008
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