AN ASSESSMENT OF THE EFFECTS OF POLLUTION ON FISHERIES AND AQUACULTURE IN JAPAN TABLE OF CONTENTS

by

Tokyo University of Fisheries
Tokyo, Japan

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M-45
ISBN 92-5-100117-5

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PREPARATION OF THIS REPORT

This report was prepared by the Tokyo University of Fisheries, under contract to FAO, as part of a cooperative project between FAO and the United Nations Environment Programme on Monitoring of Environmental Effects on Marine World Fishery Resources. A similar report on pollution off the west coast of the U.S.A. has been prepared under the same project.

	FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
	UNITED NATIONS ENVIRONMENT PROGRAMME

FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
Rome, October 1976 © FAO

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TABLE OF CONTENTS

Abstract

Preface

1.   AN OUTLINE OF WATER POLLUTION IN JAPAN

2.   THE PRESENT STATE OF FISHERIES DAMAGE DUE TO POLLUTION OF COASTAL WATERS

2.1   Damage to fisheries due to red tides

2.2   Damage to fisheries due to petroleum products and raw materials

3.   THE PRESENT STATE OF MARINE RESOURCES IN COASTAL WATERS

4.   A CASE STUDY ON THE EFFECTS OF WATER POLLUTION ON FISHERIES

4.1   The present state of pollution and fisheries in Tokyo Bay

4.1.1   Natural conditions

4.1.1.1   Geographical features
4.1.1.2   Meteorological characteristics
4.1.1.3   Hydrographic conditions

4.1.2   Background and causes of water pollution
4.1.3   Water quality and bottom deposit surveys
4.1.4   Changes in fishery yield

4.1.4.1   Shellfish
4.1.4.2   Squid and octopus
4.1.4.3   Crustaceans
4.1.4.4   Fishes
4.1.4.5   Laver

4.2   The present state of pollution and fisheries in the Seto Inland Sea

4.2.1   The present state of pollution

4.2.1.1   Red tides
4.2.1.2   Polychlorinated biphenyls
4.2.1.3   Mercury
4.2.1.4   Heavy metals and oysters
4.2.1.5   Pollution of bottom sediments
4.2.1.6   Oil pollution

4.2.2   The present state of the seaweed beds in the Seto Inland Sea
4.2.3   Fisheries and pollution
4.2.4   Counter measures for Seto Inland Sea pollution

4.2.4.1   Designation of water body classification and reinforcement of effluent standards
4.2.4.2   Adoption of a system applicable for the construction or remodelling of designated facilities
4.2.4.3   Basic policy decision-making for the approval and licensing of reclamation proposals
4.2.4.4   Promotion of pollution control programmes
4.2.4.5   Promotion of sewage treatment facilities
4.2.4.6   Development of waste oil treatment facilities
4.2.4.7   Surveillance and enforcement system for the quality of waste water
4.2.4.8   Monitoring and surveillance of water pollution

List and explanation of tables

Table 1 - Annual nation-wide statistics depicting the incidence of registered occurrences of marine pollution between 1969 and 1974. “I” denotes pollution cases related to petroleum resources and products; “II” indicates other types of pollution unrelated to oil; “T” denotes the sum total of I and II. Figures in parentheses show the number of red tide outbreaks. Data for the southwest sea area is that compiled after reversion of the Ryukyu Islands to Japan in 1972.

Table 2 - Frequency of samples exceeding the environmental quality standards for total mercury according to geographic region in Japan.

Table 3 - Regions which require(d) sediment removal operation as a counter measure of mercury pollution.

Table 4 - Execution of self-imposed control upon the taking of fish polluted with PCBs.

Table 5 - Results of a nation-wide survey on PCB pollution in water bodies, 1972.

Table 6 - Results of a nation-wide survey on the quantities of PCBs in sediments, 1972.

Table 7 - Regulations on the use of agricultural chemicals (as of 15 January 1975).

Table 8 - Changes in yields of some major fisheries (1960, 1965, 1970 and 1973).

Table 9 - Damages to cultured laver (“nori”) caused by oil pollution in Tokyo Bay (1967–1972).

Table 10 - Pollution trends in the Seto Inland Sea during the past several decades.

Table 11 - Water quality of the major industrial areas in the region of the Seto Inland Sea.

Table 12 - Surveillance results of environmental quality guidelines in the Seto Inland Sea and nation-wide.

Table 13 - Distribution of COD in the Seto Inland Sea, 1972–1974.

Table 14 - Red tide plankters which appeared in the Seto Inland Sea during outbreaks in 1974.

Table 15 - Localities of the Seto Inland Sea where concentrations of PCBs detected in fish exceeded the allowable limit of 3 ppm.

Table 16 - Pollution sources of mercury and its environmental levels in the Seto Inland Sea.

Table 17 - Average values of heavy metals in oysters from Hiroshima Prefecture, 1968–1972.

Table 18 - Area of reclaimed land in the Seto Inland Sea according to prefecture, 1955–1969.

Table 19 - Area of reclaimed land in the Seto Inland Sea according to zone: projected area of reclamation as of 1 December 1971.

Table 20 - Coastline utilization of the Seto Inland Sea, 1974.

Table 21 - Productivity of major fishery resources in the Seto Inland Sea, 1972.

List and explanation of figures

Figure 1 - The state of marine pollution in Japan as reflected by the number of registered cases of pollution outbreaks in various coastal waters (1974). From the “Maritime Safety White Paper”, the Maritime Safety Agency, 1975.

Figure 2 - Annual change in the number of registered cases of marine pollution between 1969 and 1974. Respective portions of the vertical bars of the histogram denote the following: vertical lines - oil discharged from tankers and other vessels; stippled - oil discharged from land; diagonal lines - petroleum-related cases from undetermined sources; blank - cases unrelated to oil. From the “Maritime Safety White Paper”, the Maritime Safety Agency, 1975.

Figure 3 - Outbreaks of marine pollution classified according to pollution source and type. Stippled areas of outer ring indicate oil-related pollution; unstippled areas denote pollution unrelated to petroleum (1974). From the “Maritime Safety White Paper”, the Maritime Safety Agency, 1975.

Figure 4 - Disposal of industrial wastes by means of dumping vessels (1974). Numerical figures are expressed in units of one thousand tons. Amounts of industrial wastes used for land reclamation are cited in certain cases. From the “Maritime Safety White Paper”, the Maritime Safety Agency, 1975.

Figure 5 - Geographical locations of fixed monitoring stations as well as pollutant waste dumping areas. Undarkened circle - water sampling stations; darkened circle - water and sediment sampling stations; darkened square - dumping area “A” for toxic chemicals such as mercury and cadmium; undarkened square, dumping area “B” for wastes such as slag and metallic rubbish. Principal bays are shown at the bottom; left to right: Tokyo Bay, Ise Bay, Osaka Bay and Ishinomaki Bay.

Figure 6 - The state of water pollution in some important lakes and bays. Values shown are those for chemical oxygen demand (COD) in units of parts per million (ppm). Data from the Environment Agency.

Figure 7 - Reference map illustrating geographical features around Tokyo Bay and water depth within the bay itself.

Figure 8 - Diagrammatic representation of the present state of reclamation works along the coastal areas of Kawasaki City, Tokyo, Funabashi City, Chiba City and Ichihara City. Historical development is denoted by cross-sectioned area (1951–1960), horizontal lines (1961–1965), diagonal solid lines (1966–1970), and diagonal dotted lines (1971–1973). Blank bordered areas are those still under construction. Areas enclosed by dotted lines represent dredged areas. Other symbols include those representing break-waters , shore protection works , quays or breakwaters , and wooden stockades . From the Tokyo Metropolitan Harbor Office, March, 1974.

Figure 9 - 1 - Map of surface water currents in Tokyo Bay during the winter season (mid-October to mid-April).

Figure 9 - 2 - Map of surface water currents in Tokyo Bay during the summer season (mid-April to mid-October).

Figure 10 - 1 - Map of tidal currents in Tokyo Bay at the time of the strongest northwest current.

Figure 10 - 2 - Map of tidal currents in Tokyo Bay at the time of the strongest southeast current.

Figure 11 - 1 - Salinity distribution of surface waters of Tokyo Bay during the summer (6 August 1973).

Figure 11 - 2 - - Vertical salinity distribution of Tokyo Bay during the summer (6 August 1973).

Figure 11 - 3 - - Vertical salinity distribution of Tokyo Bay during the winter (20 February 1974). Station 4 denotes the estuary of the Ara River.

Figure 12 - Fluctuations in the annual frequency of red tide outbreaks in the southern, central and northern parts, and also the entire Tokyo Bay. Abscissa denotes year; ordinate indicates the frequency of outbreaks.

Figure 13 - Seasonal differences in the frequency of red tide outbreaks in Tokyo Bay during previous years. Spring (March-May), Summer (June-August), Autumn (September-November), Winter (December-February).

Figure 14 - 1 - Yearly changes in the number of red tide species which have appeared in Tokyo Bay. By Y. Okada.

Figure 14 - 2 - Seasonal variation in the density of red tide organisms in Tokyo Bay. The red tide condition is denoted by the darkened areas; the normal condition is given by diagonal lines. By R. Hirano.

Figure 15 - Representative red tide organisms which have appeared during outbreaks. By Y. Okada.

Figure 16 - Seasonal changes in the degree of water transparency at some survey stations in Tokyo Bay. Chart to the right illustrates transparency during each month with figures indicating water depth given in units of meters. (April 1973 to March 1974)

Figure 17 - Annual fluctuations in the transparency of the water of Tokyo Bay. Inner part of the bay ; central part of the bay ; bay entrance . Report of the Chiba Fisheries Experimental Station, 1973.

Figure 18 - 1 - Surface water distribution of total organic carbon (TOC) in Tokyo Bay during the winter.

Figure 18 - 2 - Surface water distribution of total organic carbon (TOC) in Tokyo Bay during the summer.

Figure 19 - Monthly fluctuations in surface water chemical oxygen demand (COD) in Tokyo Bay. Analysis according to the alkaline method. Symbolic representation: C-12 (St-26) ; K-8 ; St.25 ; T-8 (St-4) .

Figure 20 - 1 - Distribution of total nitrates in the surface water of Tokyo Bay (October 1972).

Figure 20- 2 - Distribution of total phosphates in the surface water of Tokyo Bay (October 1972).

Figure 21 - 1 - Horizontal distribution of the mud content ratio (%) in Tokyo Bay.

Figure 21 - 2 - Horizontal distribution of values for ignition loss (%) in surface sediments of Tokyo Bay.

Figure 21 - 3 - Horizontal distribution of values for sulfide content (mg S/g) in surface sediments of Tokyo Bay.

Figure 22 - Concentrations of total mercury, cadmium, chromium, lead and arsenic in sediments of Tokyo Bay (on a dry weight basis). Position as well as size and shade of dots in groups of threes denote the year of sampling and concentration in ppm. Position of dot: Upper, 1971; Middle, 1972; Lower, 1973. Size and colouration of dot: Small white dot: less than 0.5 ppm; small black dot: 0.5 to 1.0 ppm; large black dot: greater than 1.0 ppm. Horizontal bar indicates the absence of sampling.

Figure 23 - Concentrations of five heavy metals (arsenic, cadmium, total mercury, chromium and lead) in sediments of Tokyo Bay. Values are shown as means on a dry weight basis while vertical bars show 95% confidence interval. Numbers along the abscissa denote sampling stations corresponding to those shown in Figure 16.

Figure 24 - 1 - Fisheries statistics for Tokyo Bay between 1960 and 1973. Representation of symbols: Total quantities ; shellfish ; fish ; other fisheries products .

Figure 24 - 2 - Fluctuations in the annual catch of several fish species in Tokyo Bay between 1953 and 1972. Representation of symbols: Sardine ; halibut and flounder (flatfish) ; common sea bass . Catches were taken in the inner part of the bay. (Chiba)

Figure 24 - 3 - Fluctuations in the annual catch of fisheries products in Tokyo Bay between 1953 and 1973. Representation of symbols: Total ; shellfish ; fishes ; other fisheries products ; seaweed ; number of operating days . (Chiba)

Figure 24 - 4 - Fluctuations in the annual catch of short necked clam , common shield clam , prawn , and cr crab in Tokyo Bay between 1953 and 1972. (Chiba)

Figure 24 - 5 - Fluctuations in the annual production and number of enterprises engaged in seaweed production in Tokyo Bay between 1953 and 1973. Representation of symbols: Chiba ; Tokyo ; Kanagawa . Dotted lines indicate the number of business enterprises engaged in the production of seaweed.

Figure 25 - Pathway of various pollutants into areas of the Seto Inland Sea.

Figure 26 - Distribution of chemical oxygen demand (COD) in surface waters of the Seto Inland Sea (1972). Data from the Environment Agency.

Figure 27 - Fluctuations in the number of cases of red tide in the Seto Inland Sea between 1967 and 1974. Numbers indicate the total cases as well as those which resulted in damage to fisheries (diagonally lined portion).

Figure 28 - Mercury pollution in Tokuyama Bay illustrating pollution source and areas designated for counter-measure operations. Areas with diagonal lines are those to be dredged, while those with stippling are to be subjected to land reclamation.

Figure 29 - Physicochemical measurements of bottom sediments of the Seto Inland Sea (October 1972). Values for COD, sulphur and ignition loss are shown.

Figure 30 - Annual number of oil pollution cases classified according to pollution source between 1969 and 1973. The three blocks constituting each vertical histogram represent the following sources of oil pollution: Land (upper); ship (middle); unknown (lower). Numbers within each block indicate the respective number of total cases. Data from the Maritime Safety Agency.

Figure 31 - The number of cases of oil pollution in different areas of the Seto Inland Sea. From “The Present Situation of Maritime Safety, 1974” by the Maritime Safety Agency.

Figure 32 - The number of cases of oil pollution according to vessel classification. From “The Present Situation of Maritime Safety, 1974” by the Maritime Safety Agency.

Figure 33 - Eel grass (“amamo”, Zostera) zones prior to 1965 in different regions of the Seto Inland Sea, and their rates of reduction up to 1965. Cross-hatched - area in which eel grass remains; blank - proportion of area from which eel grass has disappeared. Numbers show the area in hectares prior to 1965. Data from the Southwest Regional Fisheries Research Laboratory.

Figure 34 - Eel grass (“amamo”, Zostera) zones prior to 1965 in different regions of the Seto Inland Sea, and their reduction rates between the years 1965 to 1971. Symbolic representation and numerical denotations are the same as given in Figure 33. Data from the Southwest Regional Fisheries Research Laboratory.

Figure 35 - Changes in the area of reclaimed land in the Seto Inland Sea between 1955 and 1970. Data from the Southwest Regional Fisheries Research Laboratory.

Figure 36 - Changes in total catches of fisheries products in the Seto Inland Sea between 1928 and 1972. Data from the Southwest Regional Fisheries Research Laboratory, 1974.

Figure 37 - Changes in the amount of major fisheries products in the Seto Inland Sea. Data from the “Fishery and Aquaculture Yearbook” of the Ministry of Agriculture and Forestry for 1953, and the “Fisheries Statistics Table in the Seto Inland Sea” from the Chugoku-Shikoku Agricultural Administration Bureau for the years 1958 to 1973.

Figure 38 - Changes in the amount of major marine products (marine animals, shellfish, and seaweeds) in the Seto Inland Sea. Data from the “Fishery and Aquaculture Yearbook” of the Ministry of Agriculture and Forestry for 1953, and the “Fisheries Statistics Table in the Seto Inland Sea” from the Chugoku-Shikoku Agricultural Administration Bureau for the years 1958 to 1973.

Figure 39 - Changes in the catches of different fishes. Data from the “Fishery and Aquaculture Yearbook” of the Ministry of Agriculture and Forestry for 1953, and the “Fisheries Statistics Table in the Seto Inland Sea” from the Chugoku-Shikoku Agricultural Administration Bureau for the years 1958 to 1973.

Figure 40 - Areas of the Seto Inland Sea which have been designated as those where reclamation work should be avoided. Data from the Environment Agency.

Supplementary Figure I: Reference map of the Seto Inland Sea.

Supplementary Figure II: Reference map illustrating sea areas of the Seto Inland Sea.

Supplementary Figure III: Map illustrating the extent of oil dispersion following leakage of oil from a storage tank at the Mizushima oil refinery of the Mitsubishi Company Ltd. on 18 December 1974. Area of dispersion is according to the following representation on the dates and times indicated:

20 December, 1010 hours - Cross hatched grid
21 December, 0730 hours - Horizontal parallel lines
22 December, 0750 hours - Vertical parallel lines
23 December, 1200 hours - Stippling
24 December, 0800 hours - Diagonal parallel lines.

Data from the Maritime Safety Agency.

Abstract

This paper attempts to make a quantitative assessment of the impact of pollution on the fisheries around Japan. Shortage of data caused the study to be confined mainly to Tokyo Bay and the Seto Inland Sea, though these areas included a large proportion of the reported cases of pollution. The main cause of pollution in general, and of damage to fisheries was oil pollution, followed by red tide. The impact on fisheries was assessed from reports of direct damage, and also by examination of trends in catches. No significant decrease in total catch was observed, but within the total there were differences between species, certain species (e.g. oceanic types) tending to decrease and others increasing. The need for careful monitoring and control of pollution is stressed.

PREFACE

During the course of this study, some obstacles were encountered in the analysis of factors which affect fishery resources. The initial problems were largely those of logistics, planning and decision-making. The mode and logistics of data compilation were decided upon but the problem of data arrangement, interpretation, and assessment remained. Our work on these and related problems led to the discussion presented in the following pages.

The most difficult problem has been that of clearly identifying and measuring the impact of environmental pollution on fishery resources in general. This is due to the fact that various factors are responsible for yearly changes in fisheries production. These include impoverishment of fishing grounds due to overfishing, changes in the physical and chemical condition of the marine environment, advancements in the field of fishing techniques and gears, and consumer demand. The impact of these variables taken alone and their interplay on fisheries production still require considerable clarification and it is essential that this is taken into account when assessing the effects of environmental pollution on marine resources. Moreover, in the process of compiling nation-wide data, it became clear that an over-all assessment of trends is virtually impossible. We have therefore limited the bulk of this report to a presentation of case studies undertaken in the region of Tokyo Bay and the Seto Inland Sea. We would like to point out that data presented in this report has been collected from various isntitutions, laboratories, and fishery experimental stations. Consequently there is an admitted lack of homogeneity in terms of scope and precision, and intercalibration has been difficult or impossible. Needless to say, this has created difficulty in the assessment of actual relationships.

It is encouraging that environmental pollution in Japan has been gradually decreasing since 1972 due to the enactment of the Environmental Protection Law. We hope this trend will continue, but it will only be possible through the continuation of concerted counter-measure programmes and environmental monitoring.

As mentioned above, the regions of Tokyo Bay and the Seto Inland Sea were selected as the focal points of the discussions presented in this report. Factors which were relevant in this selection included the serious state of pollution in these areas, together with the fact that fishery statistics and results of environmental surveys are well documented for these two specific areas. We very much hope that a data base system will be set up for these specific areas to provide the foundation for accurate prediction and assessment of the effects of environmental pollution on fisheries production in the future.

The following members were responsible for the preparation of this report:

Dr. Tadayoshi Sasaki, President, Tokyo University of Fisheries

Dr. Tamao Yoshida, Professor of Environmental Protection Engineering, Department of Marine Environmental Technology, Tokyo University of Fisheries

Mr. Robert S. Izumo, M.Sc., Graduate Student (Ph.D. candidate), The University of Tokyo

Miss Harumi Kojima, Faculty Assistant, Tokyo University of Fisheries

Mr. Mannen Mishima, Graduate Student, Tokyo University of Fisheries