Table Of ContentSpringer
Tokyo
Berlin
Heidelberg
New York
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London
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K. Aida, K. Tsukamoto
K. Yamauchi
(Eds.)
Eel Biology
With 209 Figures, Including 7 in Color
Springer
Katsumi Aida, Ph.D.
Professor, Department of Aquatic Bioscience
Graduate School of Agricultural and Life Sciences
The University of Tokyo
1-1 c 1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
Katsumi Tsukamoto, Ph.D.
Professor, Ocean Research Institute
The University of Tokyo
1-15-1 Minamidai, Nakano-ku, Tokyo 164-8639, Japan
Kohei Yamauchi, Ph.D.
Professor, Division of Marine Biosciences
Graduate School of Fisheries Sciences
Hokkaido University
3-1-1 Minatomachi, Hakodate 041-8611, Japan
ISBN 978-4-431-65909-9 ISBN 978-4-431-65907-5 (eBook)
DOI 10.1007/978-4-431-65907-5
Library of Congress Cata10ging-in-Pub1ication Data
Eel biology I K. Aida, K. Tsukamoto, K. Yamauchi (eds.)
p.cm.
Includes bibliographical references and index.
1. Eels. I. Aida, K. (Katsumi), 1944-II. Tsukamoto, K. (Katsumi), 1948-III.
Yamauchi, K. (Kohei), 1942-
QL637.9.A5E452003
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Preface
The eel has long been esteemed in Japan as an important food fish that has a unique
taste. We consume as much as 130 000 tons of eel per year, and the grilled eel dish
called kabayaki is now one of the representative dishes of traditional Japanese
food culture. In Europe, eels also have been an integral part of the cuisine. How
ever, the decreases in eel resources have been a serious concern in recent years,
and the catches of glass eels as seedlings for aquaculture have shown a long-term
decrease in both Europe and East Asia. It is not yet clear if this has been caused by
global changes in the ocean-atmosphere system, the human impacts of overfish
ing and environmental disruption, or other biological factors.
To counteract these decreases in eel resources, we need to understand the causes
and mechanisms, and to develop effective management strategies for maintaining
stable eel populations. Therefore, the first goal should be to use an ecological ap
proach to gain a complete understanding of the mysterious life cycle of the fresh
water eel, which has fascinated naturalists since the age of Aristotle. We need to
start by gaining a complete understanding of the exact factors that determine the
spawning locations of each species and of how global-scale environmental changes
may affect their spawning success and glass eel recruitment.
Another high priority is the establishment of techniques for artificially matur
ing and spawning adults and rearing their larvae in order to supply sufficient num
bers of reared glass eels to meet the demand of aquaculture facilities, irrespective
of fluctuations in wild stocks. Therefore, fundamental research on the reproduc
tive physiology of eels and on the feeding behavior, nutrition, and physiological
defense mechanisms of eel larvae is needed. To attain our final goals, both ecolo
gists and physiologists must closely collaborate with each other to elucidate the
iife cycle of the freshwater eel and to succeed in the artificial production of glass
eels.
Based on this strategy, we implemented a comprehensive 5-year research project
titled "The Elucidation of the Life Cycle of the Eel and Artificial Control of Its
Reproduction" beginning in 1997. Funding for this project was provided by the
Research for the Future program of the Ministry of Education, Culture, Sports,
Science and Technology, and by the Japan Society for the Promotion of Science.
This project has resulted in breakthroughs in ecological research on the spawning
VI Preface
area and migration of the eel, and in research on the reproductive physiology and
larval rearing of the Japanese eel.
Therefore, in 2001, the last year of the project, we hosted a historic international
symposium titled "Advances in Eel Biology" and invited many experts on eel re
search from around the world to discuss recent findings about the ecology, popu
lation biology, physiology, and artificial production of seedlings of freshwater eels
in order to facilitate further progress in these research fields. In response to our
invitation, many scientists attended the symposium and presented the results of
their scientific work. Motivated by the fruitful discussions in that meeting, we be
lieve that now is an exc~llent time to publish a book that compiles all the impor
tant recent findings in one volume. We have titled this book Eel Biology, and it is
unique because it integrates the present state of knowledge concerning all aspects
of eel biology and ecology from the perspective of many authors.
We would like to express our sincere thanks to all the authors who have kindly
contributed to this landmark book on eel biology and to congratulate them on
making this work such a valuable contribution to the literature on anguillid eels.
We also express our sincere gratitude to the Ministry of Education, Culture, Sports,
Science and Technology and to the Japan Society for the Promotion of Science
whose funding has enabled us to organize one of the largest international eel sym
posia ever held and to publish this book.
Katsumi Aida
Katsumi Tsukamoto
Kohei Yamauchi
July 2003
Contents
Preface ........................................................................................................................ V
Part 1 Taxonomy, Phylogeny, Population Structure, and Speciation
1 Taxonomy of the Freshwater Eels, Genus Anguilla Schrank, 1798
s. Watanabe ........................................................................................................... 3
2 Origin and Evolution of the Freshwater Eels, Genus Anguilla
J.Aoyama ............................................................................................................. 19
3 Catadromous Eels of the North Atlantic: A Review of Molecular
Genetic Findings Relevant to Natural History, Population Structure,
Speciation, and Phylogeny
J.C.Avise .............................................................................................................. 31
Part 2 Life History
4 Leptocephali
N. Mochioka ........................................................................................................ 51
5 Metamorphosis
T. Otake ................................................................................................................ 61
6 The Glass Eel
o. Tabeta and N. Mochioka ................................................................................ 75
7 The Yellow Eel
C. Moriarty............. ................................. ............ .......... .......... ........................ .... 89
8 The Silver Eel
J. Aoyama and M.J. Miller ...................................•............................................ 107
Part 3 Migration
9 Spawning Area of the Japanese Eel
K. Tsukamoto, T.-W. Lee, and H. Fricke .......................................................... 121
VIII Contents
10 Spawning Areas of the Atlantic Eels
J.D. McCleave .................................................................................................... 141
11 The Worldwide Distribution of Anguillid Leptocephali
M.J. Miller .......................................................................................................... 157
12 Larval Transport of the Japanese Eel
S. Kimura ........................................................................................................... 169
13 The Processes of Onshore Migration of the Japanese Eel Anguilla japonica
as Revealed by Otolith Microstructure
W.-N. Tzeng ....................................................................................................... 181
14 A Review of Upstream Migration and Movements in Inland Waters by
Anguillid Eels: Toward a General Theory
E. Feunteun, P. Laffaille, T. Robinet, C. Briand, A. Baisez,
J.-M.Olivier,andA.Acou ................................................................................. 191
15 Downstream Migration of Silver-Phase Anguillid Eels
A. Haro ;. ............................................................................................................. 215
16 Migration from Continental Waters to the Spawning Grounds
EW. Tesch and N. Rohlf .................................................................................... 223
Part 4 Resources
17 Status of the European Eel Stock and Fisheries
W. Dekker .......................................................................................................... 237
18 Dynamics of Resources of the American Eel, Anguilla rostrata: Declining
Abundance in the 1990s
J.M. Casselman .................................................................................................. 255
19 The Distribution and Biology of the South Pacific Species of Anguilla
D.J. Jellyman ...................................................................................................... 275
20 Eel Resources in East Asia
K. Tatsukawa ..................................................................................................... 293
Part 5 Regulatory Mechanisms of Reproduction
21 Oogenesis in the Japanese Eel, Anguilla japonica
S. Adachi, S. Ijiri, Y. Kazeto, and K. Yamauchi ................................................ 301
22 Spermatogenesis in the Japanese Eel
T. Miura, C. Miura, and K. Yamauchi .............................................................. 319
23 The Physiology of Silvering in Anguillid Eels: Androgens and Control of
Metamorphosis from the Yellow to Silver Stage
P.M. Lokman, D.H. Rohr, P.S. Davie, and G. Young ........................................ 331
24 GTH and GnRH Molecules and Their Expression in the Japanese Eel
H. Suetake, K. Okubo, Y. Yoshiura, and K. Aida .............................................. 351
Contents IX
25 Reproductive Endocrinology of the European Eel, Anguilla anguilla
S. Dufour, E. Burzawa-Gerard, N. Le Belle, M. Sbaihi, and B. Vidal ............. 373
Part 6 Techniques for Artificial Induction of Maturation
26 Induction of Vitellogenesis
N. Sato, I. Kawazoe, Y. Suzuki, and K. Aida ..................................................... 387
27 Artificial Induction of Oocyte Maturation and Ovulation
H. Kagawa .......................................................................................................... 401
28 Induction of Sperm Maturation
H. Ohta and T. Unuma ..................................................................................... 415
Part 7 Larval Rearing and Physiology
29 Techniques for Larval Rearing
H. Tanaka ........................................................................................................... 427
30 The Digestive System of Eel Larvae
T. Kurokawa and B.H. Pedersen ...................................................................... 435
31 Hatching Enzymes in the Japanese Eel
J. Hiroi, S. Yasumasu, K. Kawazu, and T. Kaneko ........................................... 445
32 Chloride Cells in the Japanese Eel During Their Early Life Stages and
Downstream Migration
T. Kaneko, S. Hasegawa, and S. Sasai .............................................................. 457
33 Nonspecific Defense Mechanisms of the Eel
Y. Suzuki and S. Tasumi ................................................................................... 469
Subject Index ........................................................................................................... 485
Part 1
Taxonomy, Phylogeny, Population Structure,
and Speciation
1
Taxonomy of the Freshwater Eels, Genus
Anguilla Schrank, 1798
Shun Watanabe
1. Introduction
The freshwater eels of the genus Anguilla Schrank, 1798, are widely distributed in
the world and have unique characters such as a catadromous life history strategy, a
long spawning migration, and a long leptocephalus larval period. Although there
have been a large number of studies on their ecology and physiology, there have
been relatively few studies on their taxonomy. Comprehensive revisions of the ge
nus Anguilla using most or all the presently recognized species were done by Kaup
(1856), Gunther (1870), and Ege (1939) with morphological analysis. However, rela
tively little work has been done after the milestone study of Ege (1939). This lack
may have been due to the extensive nature of his study, in which he carefully ex
amined a large number of specimens of all the species of the genus Anguilla from
throughout the world. As a result, it may have been generally thought that all the
problems of the taxonomy of the genus Anguilla were completely solved. However,
the freshwater eels have several groups of species that have very similar morpho
logical features, making them difficult to distinguish, and a recent reexamination
of Ege's (1939) study found that there were still several important problems re
maining in the present taxonomy of the freshwater eels. The purpose of this chap
ter is to introduce the history of the taxonomy of the freshwater eels, to evaluate
the presently accepted taxonomy, and to propose a new taxonomy to solve the prob
lems of Ege's (1939) study.
Department of Marine Bioscience, Ocean Research Institute, The University of Tokyo, 1-15-1
Minamidai, Nakano-ku, Tokyo 164-8639, Japan
Tel. +81-3-5351-6520; Fax +81-3-5351-6514
e-mail: [email protected]
