Lake Biwa: Interactions between Nature and People

Lake Biwa: Interactions between Nature and People

Editors Hiroya Kawanabe • Machiko Nishino • Masayoshi Maehata Assistant Editors Kazuhiro Masunaga • Mark Joseph Grygier • Robin James Smith Chapter Editors Chapter 1: Keiichi Takahashi Chapter 2: Machiko Nishino Chapter 3: Machiko Nishino Chapter 4: Masaharu Yoda Chapter 5: Masayoshi Maehata Chapter 6: Masahisa Nakamura & Michio Akiyama Chapter 7: Masayoshi Maehata Appendix: Machiko Nishino, Masaharu Yoda & Masayoshi Maehata Editors Hiroya Kawanabe Machiko Nishino Lake Biwa Museum Lake Biwa Environmental Research Institute 1091 Oroshimo-cho 5-34 Yanaga-saki Kusatsu, Shiga 525-0001 Otsu, Shiga 520-0022 Japan

Masayoshi Maehata Lake Biwa Museum 1091 Oroshimo-cho Kusatsu, Shiga 525-0001 Japan

ISBN 978-94-007-1782-4 ISBN 978-94-007-1783-1 (eBook) DOI 10.1007/978-94-007-1783-1 Springer Dordrecht Heidelberg New York London

Library of Congress Control Number: 2012935426

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Springer is part of Springer Science+Business Media (www.springer.com) Preface

Lake Biwa is situated in the centre of Island in the Japanese Archipelago. It is 670.3 km2 in area, and 41.2 m and 103.6 m in mean and maximum depth, respectively. Th e lake is separated into two parts, the northern main and deeper basin and the southern small and shallower one. Th e transparency at the centre of the main basin has been decreasing during the past 50 years but is still 4–9 m, while that of the south basin is 2–3 m. It is one of the world’s ancient , having been formed originally about 4.5 million years BP about 50 km south of its present site. Around 400,000 years BP it came to its present site and became deeper. Fossils of the same species or a close relative of the largest fi sh found in the lake at present, the Biwa catfi sh Silurus biwaensis, have been discovered even in sediments from the oldest age of the lake. Some other endemic fi sh species in the lake, however, evolved in situ, especially aft er the lake deepened. In such cases, the newly derived species have a more pelagic mode of life or live in open water or show adaptations for survival in rocky shores, compared to the ancestral species which are mainly sandy or muddy littoral inhabitants with a benthonic mode of life. Th ere is a species fl ock of pleurocerid snails, Semisulcospira (Biwamelania), and its supposed ancestor S. (B.) habei had already appeared by 400,000 years BP. It is believed that human beings have lived around Lake Biwa for more than 20,000 years, and archaeological evidence demonstrating the relation of human beings and the lake goes back to 8,000 years BP. Most remarkable is the Awadu Lake Bottom sites, around 5,000 years BP, from which it is clear many species of fi shes and molluscs were eaten by ancient human settlers for a rather long time. Traces of special fi shing installations remain since ancient days: i.e. a ‘yana’ fi shweir at a river mouth and ‘eri’ pound-net for fi sh since 2,000 and 1,500 years BP, respectively. Both wooden fl oats for angling and many types of ceramic net-sinkers have also been discovered, dating since the third century. Various historical documents pertaining to the lake fi sheries survive back to the eighth century. For example, an edict promulgated in 863 prohibited any offi cer from taking fi sh away for the imperial court from the fi shing grounds around the lake except from fi shweirs located in the 4 specifi ed rivers. In 927, the ‘Engi-shiki’, a collection of laws and regulations, was promulgated, whereby we know that in Ohmi Province surrounding Lake Biwa the following goods were produced and sent to the imperial court: ‘fi sh cheese’ of crucian carp and of Biwa salmon, crucian carp with soy sauce, salted crucian carp, boiled ayu-fi sh with salt, and juvenile ayu-fi sh. Given its archaeological and historical background, Lake Biwa is not only an ancient lake in the geological and biological senses but also in a cultural sense, because the relation between human beings and nature, especially the lake, can be traced back to several thousand years BP. In other words, Lake Biwa has developed as a ‘life-culture complex’ over a long time. Th e present book on Lake Biwa is written from this point of view. * Around the lake there are many academic institutions. Th e oldest are the Shiga Fishery Research Station and the Otsu Hydrobiological Station (now the Center of Ecological Research) of University, established in 1900 and 1914, respectively. Th e staff s of these stations have devoted their eff orts to limnological, biological, and fi sheries research continuously since then, and many scientifi c results have been cumulated up to now. Rather recently, the Lake Biwa Research Institute, LBRI (now Lake Biwa Environmental Research Institute, LBERI), was established in 1982 and the Lake Biwa Museum (LBM) in 1996, both being set up and operated by the Shiga Prefectural Government. Th e former is dedicated mainly to research on environmental problems and issues related to the planning of prefectural policy, and the latter is a research-oriented museum dedicated to the ‘relation between lake and people’, with exhibitions, nature observations, lectures, etc. and with much involvement of the general public. Concerning Lake Biwa many scientifi c books has been published up to now but most of them are written in Japanese. In 1975, ‘Productivity of freshwater communities in Lake Biwa’ edited by the JIBP-PF Research Group of Lake Biwa (chief: T. Miura) was published as a chapter in the book “Productivity of Communities in Japanese Inland Waters”. Its coverage was restricted, however, mainly to Shiodu Bay, at the northern end of the lake, as one result of the International Biological Programme in Japan. In 1984 the book “Lake Biwa” (ed. S. Horie) appeared as a volume of the series “Monographiae Biologicae”. It was a rather comprehensive book that included six chapters conveying general features, geoscientifi c features, modern limnology (meteorology, physical, chemical and biological limnology, and metabolism), vi Preface

paleolimnology (non-biological features, Pleistocene climatic change, ancient lake viewed from paleobiostratigraphy and paleogeochemistry), biogeography, and infl uence of human activities. In particular it was based on the results of analyses of several boring cores taken from the lake sediments in the 1970s and early 1980s. In 1997, the ‘International Conference on Ancient Lakes: Th eir Biological and Cultural Diversities’ was held at the Lake Biwa Museum, and most papers read at the conference appeared in three books: “Ancient Lakes, their Cultural and Biological Diversity” (ed. H. Kawanabe, G. W. Coulter and A. C. Roosevelt 1999), “Ancient Lakes: , Ecology and Evolution” (ed. A. Rossiter and H. Kawanabe 2000), and “Archaeology of World Lakes” (ed. A. Matsui and K. Makino 2000). In these volumes, respectively, 2, and 3, 8 chapters were dedicated to various aspects of Lake Biwa. * Th e concept of the present book was fi rst suggested in 1999 by Professor David L. G. Noakes, Oregon State University, and several members of LBM and LBERI have discussed in recent years how to achieve it. As was mentioned above Lake Biwa is a ‘Life-culture complex’. To refl ect this the book includes the following seven chapters: (1) Geological history; (2) Biology; (3) Ecological change; (4) Historical relations of people and the lake; (5) People’s use of the lake and their life-style; (6) History of the lake and basin management; and (7) Environmental conservation. Each chapter had section editor(s) as indicated in the contents. As the general supervisor of this book, I would like to extend my sincere thanks to my old friend David L. G. Noakes for his kind suggestion and for establishing our connection to the publisher, and to Drs. M. Akiyama (University of ), M. Maehata (LBM), M. Nakamura (former Director of LBRI), M. Nishino (LBERI), K. Takahashi (LBM), and M. Yoda (LBM) for their eff orts as each section editor for their extreme eff orts to make this book. Th anks are also given to Drs. M. J. Grygier (LBM) and R. Smith (LBM) for polishing the English of much of the submitted manuscripts.

21st January, 2012: Th e starting day of the coldest 2 weeks in Japan according to traditional beliefs

Lake Biwa Museum, 1091 Oroshimo-cho, Kusatsu Hiroya Kawanabe Shiga 525-0001, Japan e-mail: [email protected]

References

Horie S (ed) (1984) Lake Biwa. Monographiae Biologicae, vol 54. Dr. W. Junk Publishers, Dordrecht JIBP-PF Research Group of Lake Biwa (chief: Miura T) (ed) (1975) Productivity of freshwater communities in Lake Biwa. In: Mori S, Yamamoto G (eds) JIBP Synthesis, vol 10, productivity of communities in Japanese Inland waters. University of Press, Tokyo, pp 1–45 Kawanabe H, Coulter GW, Roosevelt AC (ed) (1999) Ancient lakes: their cultural and biological diversity. Kenobi Productions, Ghent. Matsui A, Makino K (ed) (2000) Archaeology of world lakes. Kuba Pro., Tokyo (in Japanese with English summary) Rossiter A, Kawanabe K (ed) (2000) Ancient lakes: biodiversity, ecology and evolution. Advances in ecological research, vol 31. Academic Press, San Diego. Profile of Lake Biwa

Area of Shiga Prefecture 4,017.00 km2 Catchment area of the lake 3,174.00 km2 Nagahama city 2 Shiotsu-hama Area of the lake 670.25 km Length (North-South) 63.49 km Takashima Maximum width (East-West) 22.80 km city Minimum width (East-West) 1.35 km Aiba Nagahama city 22.8 km Shimo-sakahama Circumference 235.20 km Elevation 85.614 m above the lowest North Basin sea level of Osaka Bay 84.371 m above mean sea 63.49 km level of Tokyo Bay Maximum depth 103.58 m Otsu city 1.35 km Mean depth (North Basin) 44.0 m Ima-katata Moriyama city Konohama-cho Mean depth (South Basin) 3.5 m South Basin Volume 27.5 billion m3 Residence time of water 5.5 years Otsu city Number of the first grade river 118 Tomonoura flowing into the lake Number of natural outlet 1 (Seta River ) Age of the present lake ca. 400,000 years

References

Geographical Survey Institute (2010) Zenkoku Todofuken Shikuchoson-betsu Menseki-shirabe [The area of the prefectures and cities in Japan] (in Japanese) Kitamura S, Tsurumaki M, Endo S (1983) Shusuiiki no suimon-kankyo to suiri-kankyo [Hydrological and hydraulic environment of the catchment area]. In: Biwako Henshu-iinkai [Committee of ‘Lake Biwa’] (ed), Biwako: sono Shizen to Shakai [Lake Biwa: its nature and society], Sanraizu Shuppan, Hikone, pp 53–61 (in Japanese) Shiga Prefecture (2010) Environment of Shiga. http://www.pref.shiga.jp/multilingual/english/environment/files/2syo.pdf (25 Jan 2011)

Topic 1 The Naming of Lake Biwa Yo s h i h i r o K i m u r a

Lake Biwa, which is one of the oldest lakes in the world, of Chinese poetry composed by Keijoshurin, a monk of formed near its present location about 4 million years ago. Shokokuji temple in Kyoto. Th e use of the name Biwa-ko Despite its long history, the current name of the lake, became common aft er 1689 because of the popular diary Biwa-ko in Japanese, was introduced to the public only of the Confucianist scholar Kaibara Ekiken. In his diary, quite recently, approximately 320 years ago. Th e origin of aft er describing the overall shape of the lake and that of the name is described here. the stringed instrument biwa, he explicitly stated, “it is Literature sources reveal that the lake had various therefore called Biwa-ko .” Th ereaft er, this name started to names in the beginning, before being called Biwa-ko . In appear in literature, ukiyo-e (a genre of Japanese wood- Keiranshuyoshu, a book compiled in the early fourteenth block prints), and maps, and its use became ubiquitous. In century, it was mentioned for the fi rst time that the lake’s particular, Ino Tadataka, a famous geographical surveyor outline resembled the shape of a biwa , a traditional in the mid-eighteenth century, completed an accurate map Japanese (see Color page 1). According to this book, of the lake using the name of Biwa-ko . the name-giver of the lake was Benzaiten, the goddess As for how the name Biwa-ko became popular, its enshrined on the island of Chikubushima in the northern relation with the sound of the biwa might be one reason. part of the lake. Benzaiten was originally the goddess of Words describing waves have been commonly used since water, Sarasvati, who presided over a mystical river of the ancient times in Japanese poetry as epithets, or makurako- same name in Hindu mythology, and she is depicted as toba, in reference to Lake Biwa. Th e sound of the biwa is holding a biwa . As a guardian deity of water and , reminiscent of the sound of waves lapping on the shore. she was brought to Japan along with Buddhism in the Nara Benzaiten is also known by the name of Myo’onten or Period (710–794 AD), from India through . Bionten, who presides over sound. Why would the shape of the lake be associated with the Th ere are countless lakes in the world, among which biwa held by Benzaiten? Koso (1274–1347), a famous monk Lake Kinneret (the Sea of Galilee) in Israel is one of those of Enryakuji temple on Mt. Hiei overlooking the lake, who named aft er an instrument, like Lake Biwa. Th e name wrote Keiranshuyoshu , viewed Benzaiten as a goddess Kinneret originated from kinnor , a Hebrew word for harp. protecting both Mt. Hiei and the lake. From the top of the Th e local people believe that it is derived from the sound mountain at a height of 843 m, he may have contemplated of the waves, resembling the tones of a harp. If so, this the shape of the lake while being inspired by the biwa held by constitutes a remarkable parallel with the naming of Lake Benzaiten. Actually, the top of Mt. Hiei off ers a greater view of Biwa. It can draw inference from this fact that the shape of Lake Biwa than any other mountains surrounding the lake. the lake and the similarity in the sound of biwa and lapping Th e current Japanese name of Lake Biwa fi rst appeared waves of the lake are deeply associated with the naming of in a literature source in the early sixteenth century. Th is Lake Biwa. It is a precious lake providing us with beautiful was Kojo Hakkei (Eight Views of the Lake), a collection scenery along with cultural aff ection.

Y. Kimura () Seian University of Arts and Design, 4-3-1 Oginosato-higashi, Otsu, Shiga 520-0248, Japan e-mail: [email protected]

Contents

Profi le of Lake Biwa ...... vii Topic 1 Th e Naming of Lake Biwa ...... ix Yoshihiro Kimura

1 Geological History and Transition of the Biota of Lake Biwa ...... 1 Keiichi Takahashi 1.1 Geomorphology of Lake Biwa and the Surrounding Region ...... 3 Yoshihiro Uemura 1.2 Geological History of Lake Biwa ...... 9 Yasufumi Satoguchi 1.3 Origin and Temporal Succession of the Cyprinid Fish Fauna in Lake Biwa ...... 17 Tsuneo Nakajima Topic 2 Fossil Biwa Catfi sh, Silurus biwaensis, from Paleo-lake Biwa ...... 25 Midori Kobayakawa 2 Biodiversity of Lake Biwa ...... 31 Machiko Nishino 2.1 Protozoa of Lake Biwa ...... 37 Yasushi Kusuoka 2.2 Characteristics of the Phytoplankton Flora and Long-term Changes in the Phytoplankton Community of Lake Biwa ...... 41 Shigeo Tsujimura · Satoshi Ichise 2.3 Submerged and Waterside Plant Changes ...... 49 Etsuji Hamabata 2.3.1 Submerged Macrophyte Flora and its Long-term Changes ...... 51 Etsuji Hamabata · Yoshihito Yabu’uchi 2.3.2 Wetland Plants Growing on the Shore of Lake Biwa: Littoral, Hygrophyte, and Psychrophyte Floras ...... 61 Shinji Fujii · Yuko Kaneko 2.4 Benthic and Pelagic Invertebrate Fauna of Lake Biwa ...... 71 Machiko Nishino 2.4.1 Diversity and Distribution of Freshwater Sponges (Porifera: Spongillidae) in Lake Biwa ...... 73 Yoshiki Masuda 2.4.2 Flatworms (“Turbellarians”) and Ribbon Worms (Nemerteans) of Lake Biwa ...... 77 Masaharu Kawakatsu · Machiko Nishino 2.4.3 Diversity and Distribution of Aquatic Oligochaetes (Annelida, Clitellata) in Lake Biwa ...... 79 Akifumi Ohtaka · Machiko Nishino xii Contents

2.4.4 of Lake Biwa and its Long-term Changes ...... 85 Machiko Nishino 2.4.5 Crustacea of Lake Biwa ...... 89 Machiko Nishino 2.4.5(1) Cladocera of Lake Biwa ...... 91 Susumu Tanaka 2.4.5(2) Pelagic Copepods ...... 93 Keiichi Kawabata 2.4.5(3) Malacostraca ...... 97 Machiko Nishino 2.4.5(4) Ostracods of Lake Biwa ...... 99 Robin J. Smith 2.4.6 Aquatic Insects ...... 103 Machiko Nishino 2.4.6(1) Mayfl ies of Lake Biwa ...... 105 Shin-ichi Ishiwata · Machiko Nishino 2.4.6(2) Order Trichoptera ...... 109 Makoto Uenishi · Kazumi Tanida 2.4.6(3) Chironomid Fauna (Diptera: Chironomidae) of Lake Biwa, with Emphasis on the Changes in Recent Years ...... 113 Eiso Inoue · Tadashi Kobayashi · Machiko Nishino 2.4.6(4) Th e Dragonfl y and Damselfl y Faunas of Lake Biwa and their Long-term Changes ...... 117 Kazuhiro Masunaga 2.5 Characteristics of the Ichthyofauna of Lake Biwa, with Special Reference to its Long-term Changes ...... 119 Masayoshi Maehata 2.6 Amphibians and Reptiles in and around Lake Biwa ...... 123 Masafumi Matsui 2.7 Characteristics and Long-term Trends of the Avifauna of Lake Biwa ...... 129 Hiroshi Hashimoto · Hisashi Sugawa · Kayoko Kameda Topic 3 Endemic Diatoms of Lake Biwa ...... 135 Taisuke Ohtsuka Topic 4 Biology of the Common Reed (Phragmites australis) surrounding Lake Biwa ...... 137 Yuko Kaneko Topic 5 Leeches of Lake Biwa ...... 139 Tetsuya Itoh Topic 6 Extinction of the Japanese Otter Lutra nippon ...... 141 Motokazu Ando Contents xiii

3 Ecological Changes in Lake Biwa...... 155 Machiko Nishino 3.1 Ecological Changes in the Littoral of Lake Biwa and its Adjacent Areas ...... 157 Machiko Nishino · Yoshihiro Azuma · Masaru Tatsumi · Yuko Kaneko 3.1.1 Th e Changes in Lakeshore Landforms of Lake Biwa ...... 161 Masaru Tatsumi 3.1.2 Characters and Changes of Shore Vegetation of Lake Biwa ...... 169 Yasushi Sasaki · Yuhide Murakami · Yuko Kaneko 3.1.3 Long-term Changes of Submerged Macrophytes in the South Basin of Lake Biwa ...... 175 Hiroki Haga 3.1.4 Non-indigenous Species in and around Lake Biwa ...... 179 Katsuki Nakai · Yuko Kaneko 3.2 Ecological Changes in the Off shore of Lake Biwa ...... 189 Machiko Nishino 3.2.1 Lake Biwa’s Off shore and its Biogeochemical Processes ...... 191 Kazuhide Hayakawa · Shigeo Tsujimura 3.2.2 Measurement of Primary Productivity in Lake Biwa ...... 197 Toshiyuki Ishikawa 3.2.3 Fish Predation on Pelagic Zooplankton ...... 201 Keiichi Kawabata 3.2.4 A Food Web and its Long-term Dynamics in Lake Biwa: A Stable Isotope Approach ...... 205 Noboru Okuda · Tomohiro Takeyama · Takefumi Komiya · Yoshikazu Kato · Yutaka Okuzaki Jin’ichi Karube · Yoichiro Sakai · Michio Hori · Ichiro Tayasu · Toshi Nagata 3.3 Warming and Hypoxia in Lake Biwa ...... 211 Toshiyuki Ishikawa · Michio Kumagai Topic 7 An Analysis of the Lake Biwa Shoreline Changes using GIS ...... 217 Yoshihiro Azuma · Masaru Tatsumi Topic 8 Occurrences of Uroglena Red Tides and Cyanobacterial Blooms in Lake Biwa ...... 223 Shigeo Tsujimura · Kanako Ishikawa Topic 9 Impacts of Water Movements on Dissolved Oxygen Concentrations in the Central Basin of Lake Biwa ...... 225 Chunmeng Jiao Topic 10 Microbes as Indicator Species in Low Oxygen Environments ...... 231 Kanako Ishikawa · Seiko Furuta · Takuo Nakajima 4 History of the Relationship between People and Lake Biwa ...... 239 Masaharu Yoda 4.1 Period of Coexistence ...... 241 Masaharu Yoda 4.1.1 Life in the Jomon and Yayoi Periods ...... 243 Fumio Ueda xiv Contents

4.1.2 Technologies and Roles of Ancient Watercraft s on Lake Biwa ...... 249 Yozo Yokota 4.1.3 Th e Leaders of the Kofun Period and Transportation on Lake Biwa ...... 257 Shuhei Hosokawa 4.2 Period of Utilization ...... 263 Masaharu Yoda 4.2.1 Ancient Ports of Lake Biwa ...... 265 Nobuya Ohashi 4.2.2 Medieval Social Relationships and Lake Biwa Fisheries ...... 269 Michinori Hashimoto 4.2.3 Development of Water Transportation on Lake Biwa and Prosperity of the Port Towns ...... 275 Eiji Hatanaka 4.2.4 Maruko-Bune and its Role in Lake Transportation...... 281 Kumi Makino 4.3 Period of Exploitation ...... 285 Masaharu Yoda 4.3.1 People’s Livelihoods and Utilization of Attached Lakes ...... 287 Shizuyo Sano 4.3.2 Th e Long-held Idea of a Lake Biwa ...... 293 Masaharu Yoda 4.3.3 Th e Recent Shift in the Role of Lake Biwa from Transportation to ...... 295 Masaharu Yoda Topic 11 Mysteries of Underwater Remains in Lake Biwa ...... 299 Osamu Hama Topic 12 Otsu-Kyo: Th e Lakeshore Capital ...... 301 Hiromichi Hayashi Topic 13 Castles built on the Shores of Lake Biwa; from Nobunaga’s Era through to Hideyoshi’s Era...... 303 Masayuki Kido Topic 14 Festivity and Folklore of Lake Biwa ...... 305 Yoshikazu Hasegawa 5 Th e Use of Lake Biwa and People’s Lifestyle ...... 309 Masayoshi Maehata 5.1 Fisheries in and around Lake Biwa ...... 311 Masayoshi Maehata 5.1.1 Recent Changes in the Lake Biwa Fisheries ...... 313 Yasuhiro Fujioka · Masayoshi Maehata 5.1.2 Various Methods Developed in and around Lake Biwa ...... 317 Yasuhiro Fujioka · Masayoshi Maehata 5.1.3 Propagation and Conservation of Fishery Resources ...... 327 Yasuhiro Fujioka · Masayoshi Maehata Contents xv

5.2 Rural Daily Lives and Water Use Cultures in the Lake Biwa Area...... 331 Atsushi Makino 5.2.1 People’s Subsistence Activities in the Lake Biwa Basin ...... 333 Atsushi Makino 5.2.2 People’s Use of River Water around Lake Biwa ...... 337 Miki Kawata 5.2.3(1) Traditional Culinary Culture of Shiga Prefecture ...... 343 Masako Horikoshi 5.2.3(2) Tap Water, Sewage Systems and the Modern Irrigation System ...... 349 Atsushi Makino Topic 15 Fishery Rights and Management ...... 353 Yasuhiro Fujioka Topic 16 Utilization of Young Ayu Fish ...... 355 Yasuhiro Fujioka Topic 17 Invasions of New Fish Diseases to the Lake ...... 357 Yasuhiro Fujioka Topic 18 Waterside Living and Landscape ...... 359 Ping Yang Topic 19 Th e Traditional Baths used in Houses in Shiga Prefecture ...... 361 Fumiko Oi Topic 20 Female Farmers in Shiga Prefecture ...... 365 Tamaki Kashio 6 Evolving History of Lake Biwa and Yodo River Basin Management ...... 371 Masahisa Nakamura · Yoshihiko Ogino · Michio Akiyama · Kunihiro Moriyasu Introduction ...... 371 6.1 Overview of Lake Biwa and Yodo River Basin ...... 371 6.1.1 Physical and Geographical Features ...... 371 6.1.2 Flood Control ...... 372 6.1.3 Water Resources Development ...... 372 6.1.4 Lake Biwa Comprehensive Development ...... 373 6.1.5 Evolving Challenges ...... 374 6.2 Brief History of Lake Biwa Flood Control ...... 374 6.2.1 A Legacy of Lake Biwa Flood Control ...... 374 6.2.2 From Premodern to Early Modern Times ...... 376 6.2.3 Dawn of Full-Fledged Lake Biwa and Yodo River Flood Control Infrastructure Development ...... 377 6.2.4 From the LBCDP Era to the Present ...... 381 6.3 Water Resource Development in Lake Biwa Region ...... 384 6.3.1 Overview ...... 384 6.3.2 Water Needs and Management Challenges ...... 386 xvi Contents

6.3.3 Low Flow Regulation: Some Dictating Facts...... 386 6.3.4 Key Water Resource Development Issues ...... 387 6.3.5 Developing the Lake Biwa Comprehensive Development Plan ...... 388 6.3.6 Irrigation Improvement Projects in Lake Biwa Surroundings ...... 389 6.3.7 Water Use Changes in Urban and Industrial Areas ...... 392 6.3.8 From Water Supply Management to Water Demand Management ...... 395 6.4 LBCDP: Its Frameworks, Accomplishments and Emerged Issues ...... 396 6.4.1 Legal Framework ...... 396 6.4.2 Financial Framework ...... 396 6.4.3 Extension of the Act and Inclusion of Water Quality Improvement Projects ...... 398 6.4.4 LBCDP Accomplishments and Legacies ...... 398 6.4.5 Environmental Conservation Problem and Lake Biwa Lawsuit ...... 404 6.5 Post-LBCDP Developments ...... 404 6.5.1 Changes in Downstream Water Demands ...... 404 6.5.2 Restoration of Ecosystem Integrity and Water Quality ...... 406 6.5.3 Th e Changed Agenda...... 408 6.6 Th e Challenges Ahead ...... 413 Topic 21 Lake Biwa ...... 415 Masayoshi Maehata 7 Environmental Conservation of Lake Biwa ...... 419 Masayoshi Maehata 7.1 , Citizens Movements, and Administrative Countermeasures ...... 421 Masayoshi Maehata 7.1.1 Water Conservation Policy of Shiga Prefectural Government ...... 423 Toshiaki Kagatsume 7.1.2 Th e Soap Movement ...... 429 Atsushi Makino 7.1.3 Issues for Reduction of Pollution Loads from Point and Nonpoint Sources...... 433 Takuya Okubo 7.1.4 New Issue—COD Increase in the Water of Lake Biwa ...... 441 Kazuhide Hayakawa · Takahiro Okamoto 7.2 Deterioration of the Lake’s Ecosystem and Conservation Measures ...... 447 Machiko Nishino 7.2.1(1) Shiga Prefectural Government Measures for the Conservation and Restoration of Common Reed Marshes: Ordinance on the Conservation of Reed Beds around Lake Biwa ...... 449 Yuko Kaneko · Minako Ashiya Contents xvii

7.2.1(2) Loss and Reestablishment of Water Networks comprising Rice Fields, Waterways, and Lake Biwa: Implications for Fish Populations ...... 455 Masayoshi Maehata 7.2.1(3) Water Level Management Trials for Conserving the Lake Biwa Ecosystem ...... 459 Masayoshi Maehata · Kunihiro Moriyasu 7.2.2 Toward the Restoration of the Reclaimed “Hayasaki Lagoon” around Lake Biwa, Central Japan ...... 463 Machiko Nishino · Northern Shiga Offi ce of Environmental and General Aff airs, Shiga Prefectural Government 7.2.3 Th e Explosive Development and Control of Aquatic Weeds ...... 469 Etsuji Hamabata · Shigenori Sugimura · Kanako Ishikawa 7.2.4 Countermeasures Against Invasive Non-indigenous Species ...... 475 Katsuki Nakai 7.2.4(1) Regulations and Control of Invasive Non-indigenous Species ...... 477 Katsuki Nakai 7.2.4(2) Invasive Alien Plant Species in the Shore Areas surrounding Lake Biwa ...... 485 Yuko Kaneko 7.2.5 Population Increase of the Great Cormorant Phalacrocorax carbo and Measures to Reduce its Damage to the Fisheries and Forests of Lake Biwa ...... 491 Kayoko Kameda 7.2.6 New Challenge of Citizen Participation for Environmental Conservation ...... 497 Yuichi Sato Topic 22 Project for Restoring Paddy Fields as Nursery Grounds for Fishes...... 503 Masayoshi Maehata · Akihiro Hori Topic 23 Ramsar Convention and Wintering Waterbirds in Lake Biwa ...... 505 Hisashi Sugawa · Hiroshi Hashimoto Topic 24 Future Vision of a Sustainable Shiga and the Roadmap for Its Actualization by 2030...... 507 Jaegyu Kim · Takashi Iwakawa

Appendix ...... 515 Machiko Nishino · Masaharu Yoda · Masayoshi Maehata

Species Index ...... 733

Subject Index ...... 737

Color Plates

‘Biwa’: Japanese traditional instrument. Lake Biwa is named after this instrument. See Topic 1 (photo courtesy of Museum) Aerial view of Lake Biwa showing Chikubushima Island in the foreground (photo courtesy of Shiga Prefectural Government)

Aerial view of Lake Biwa: around the Biwa-ko Ohashi Bridge (photo courtesy of Shiga Prefectural Government)

Aerial view of the southern part of Lake Biwa: residential and business districts of Otsu City, the Omi-Ohashi Bridge, and an eri-fishing trap in the foreground (photo by R. J. Smith) Changing seasons around Lake Biwa

Spring: Oura is known for its magnificent cherry trees (photo courtesy of Shiga Prefectural Government)

Summer: Omi-Maiko Beach, one of many swimming beaches in the western shore of Lake Biwa (photo courtesy of Shiga Prefectural Government)

Autumn: Chikubushima Island before sunset: a small island in northern Lake Biwa. See Topic 1 (photo by M. Matsuda)

Winter: Lake Biwa becomes a paradise for waterfowl in this season (photo by M. Maehata) Chapter 1 Geological history of Lake Biwa and its biota

Outcrop of the Ko-Biwako Group in the Hattori River. This area was the site of the first paleo-lake, ca. 3.5 Ma. See Chapter 1-2 (photo by Y. Satoguchi)

This clay bed formed on the bottom of Lake Katata. Faults like that in this photo occurred around Lake Biwa after ca. 0.4 Ma. See Chapter 1-2 (photo by Y. Satoguchi)

Eb-Fukuda Tephra. This bed of volcanic ash from 1.75 Ma represents fallout from an explosive volcanic eruption 200 km away to the east. See Chapter 1-2 ( photo by Y. Satoguchi)

Pharyngeal tooth fossils of Cyprinus (Mesocyprinus) okuyamai unearthed from the Oyamada clay layer formed ca. 3.5 Ma. See Chapter 1-3 (photo by T. Nakajima) Chapter 2 Biodiversity and its changes in Lake Biwa

(1) Extinct organisms in and around Lake Biwa

Japanese rose bitterling, Rhodeus ocellatus kurumeus, 4-5 cm standard length (SL) (photo by H. Akiyama)

Japanese otter Lutra nippon: Stuffed specimen at the Shimono-kae Elementary School, Kochi Prefecture, Shikoku Island. See Topic 6 (photo by M. Ando)

Kissing loach (Parabotia curta), 15-20 Golden venus fish (Hemigrammocypris Potamogeton dentatus from cm SL (photo by H. Akiyama) rasborella), 4-6 cm SL. This fish has not been Lake Tega-numa, Chiba found in Lake Biwa for near 30 years (photo by Prefecture, the Kanto District H. Akiyama) (photo by E. Hamabata) (2) Endemic species & varieties of protists and plants of Lake Biwa

Aulacoseira nippo nica Stephanodiscus suzukii Pediastrum biwae Difflugia biwae (photo by S. Ichise) (photo by S. Ichise) (photo by S. Ichise) (photo by S. Ichise)

Vallisneria asiatica var. biwaensis (photo by E. Hamabata) Potamogeton biwaensis (photo by E. Hamabata) (3) Endemic benthic invertebrates of Lake Biwa (photographs by M. Nishino)

See Chapter 2

Hyriopsis schlegeli (adult: 22.4 cm SL) Oguranodonta ogurae Inversiunio reinianus (adult: 7.7 cm SL) (adult: 4.75 cm SL)

Corbicula sandai (adult: ca. 41 mm SL (left); Pisidium kawamurai Radix onychia (adult: 11.1 mm SH (left); live: small shell; 4.8 mm SL (right)) (adult: 5.1 mm SL) ca. 11.0 mm SH (right))

Valvata biwaensis (adult: 4.2 mm SW) Gyraulus biwaensis (adult: 3.8 mm SW)

Semisulcospira (Biwamelania) multigranosa Semisulcospira (Biwamelania) Semisulcospira (Biwamelania) (adult: 27.7 mm SH; embryonic: 5.0 mm, reticulata (adult: 43.3 mm SH; ourense (adult: 28 mm SH; 3.2 mm SH) embryonic: 3.6 mm SH) embryonic: 2.6 mm SH) (3) (continued) Endemic of benthic invertebrates of Lake Biwa (photographs by M. Nishino)

Jesogammarus Ephoron limnobium (larva:13.0 mm BL, (left); male: BL (Annanogammarus) annandalei Kamaka biwae, (male: 2.4 mm unmeasured (right) (photos by S. Ishiwata) (male: 10.9 mm BL) long (upper); female: 2.5 mm long (lower))

Bdellocephala annandalei (adult: 21 mm BL (left); Copulating Apatania biwaensis cocoon: 2.7 mm in diameter (right)) (4) Endemic species & subspecies of fish of Lake Biwa, See Chapter 2-5 (Photographs courtesy of Lake Biwa Museum (LBM))

Biwa salmon, male (Oncorhynchus masou subsp.), Biwa ayu (Plecoglossus altivelis subsp.), 8-10 cm SL 30-60 cm in standard length (SL)

Oily minnow (Sarcocheilichthys Biwa minnow (Sarcocheilichthys Sugo gudgeon (Squalidus chankaensis biwaensis), 15-17 cm SL variegatus microoculus), 13-20 cm SL biwae), 10-13 cm SL (4) (continued) Endemic species & subspecies of fish Lake Biwa, See Chapter 2-5

Round crucian carp (Carassius auratus grandoculis), 20-35 cm SL Biwa culter (Ischikauia steenacheri), 25-40 cm SL

Deep-bodied crucian carp (Carassius cuvieri), Willow minnow (Gnathopogon Yodo gudgeon (Biwia 20-40 cm SL caerulescens), 8-13 cm SL yodoensis) 5-6 cm SL

Biwa striated spined loach Biwa yellow-gill (Rhinogobius sp. (Cobitis sp. S), 7-8 cm SL BW), 3-4 cm SL

Biwa sculpin (Cottus reinii), 10-12 cm SL

Large striated striped loach Biwa goby (Gymnogobius isaza), (Cobitis sp. L), 8-11 cm SL 6-8 cm SL

Rock catfish (Silurus lithophilus), 50-60 cm SL Biwa catfish (Silurus biwaensis), 70-110 cm SL Chapter 4 (partially Chapter 5) History of the relationship between people and Lake Biwa

The last Maruko-bune. See Chapter 4-2-4 (photo by Investigation of remains under water. See Topic 11 (photo M. Yoda) courtesy of Shiga Prefectural Board of Education)

The Awazu Site on the lake-bottom. See Chapter Hiyoshi San’nosai [San’no Festival of the Hiyoshi Grand Shrine]. See 4-1-1 (photo courtesy of Shiga Prefectural Board Topic 14 (photo by M. Yoda) of Education)

Funa-zushi. See Chapter 5-2-3(1) (photo by Awazu Goku [Offering to the lake god]. See Topic 14 (photo by M. Yoda) M. Maehata) Chapter 5 The use of Lake Biwa and people’s lifestyle: Fishing in and around Lake Biwa

Funa Sashi-ami fishery (gill net for crucian carp) (left) and crucian carp (right) caught. See Chapter 5-1-2 (photos by T. Sato)

Eri fishery. See Chapter 5-1-2 (photo by M. Maehata) Yotsude-ami fishery in the lower reaches of the Ado River. See Chapter 5-1-2 (photo courtesy of Lake Biwa Museum [LBM])

Jibiki-ami (seine net) fishery formerly operated at Oki-shima Island, northern basin of Lake Biwa. See Chapter Yana fishery (Kattori-yana) in th Ado River. See Chapter 5-1-2 5-1-2 (photo courtesy of LBM) (photo by M. Yoda) Chapter 6 Evolution toward integrated basin management in Lake Biwa and the Yodo River basin

Seta River Wier (left ‘Setagawa Araizeki’ in Japanese); water level of Lake Biwa is controlled by this wier. Its maximum flow is 800 tons/sec. A portion of its predecessor, the Nango Wier (right, ‘Nango Araizeki’ in Japanese), built in 1905 ( Era) is preserved just upstream from the present wier. See Chapter 6-1-3 (photos courtesy of Biwako Rivers Office, Kinki Regional Development Bureau, the Ministry of Land Infrastructure, Transport and Tourism of Japan (right) and M. Maehata (left))

Lakeside Road (lake levee), which was built as part of Oki-shima port in Omi-Hachiman city, one of the renewed the Lake Biwa Comprehensive Development Project, ports built as part of the Lake Biwa Comprehensive interrup ting the continuity between water and land of Development Project (photo by M. Maehata) the water ecotone (photo by M. Maehata) Chapter 7 Environmental conservation of Lake Biwa Alien fishes of North American origin caught by seine net at Kitakomatsu beach, north basin of Lake Biwa. See Chapter 7-2-4(1) (photo by M. Maehata)

Jibiki-ami (seine net) fishing, which is now undertaken only several times per year to entertain tourists. In this event, the fishes caught are usually used as the basis for environmental education benefiting the participants. See Chapter 5-1-2 (photo by M. Maehata) Chapter 7 (continued) Environmental conservation of Lake Biwa

Water lettuce (Pistia stratiotes) growing thickly in Akanoi Bay, 2007. See Chapter 7-2-3(1) (photo by M. Maehata)

Extermination of Senegal tea plant (Gymnocoronis spilanthoides) by voluneers. See Chapter 7-2-3(1) (photo by K. Nakai)

Extermination of alien plant, water lettuce (Pistia stratiotes), using a waterweed mowing craft. See Chapter 7-2-3(1) (photo by K. Nakai)

Damage by the Great Cormorant (Phalacrocorax carbo) is observed in the forest of the Isaki Peninsula, Omi-Hachiman city, overlooking the beach in the north basin of Lake Biwa. See Chapter 7-2-4 (photo by M. Maehata)

Hayazaki-naiko [Hayazaki attached lake], site of restoration experiment. See Chapter 7-2-1(4) (photo by M. Nishino)

Lake Biwa is a paradise for waterfowl. In winter, various waterfowl, firstly many kind of duck coming from northern countries, are obsererved. See Topic 25 (photo by M. Maehata)