STOCKENHANCEMENT ANDSEARANCHING - download.e …€¦ · Section 1: Present Situation of Stock...
Transcript of STOCKENHANCEMENT ANDSEARANCHING - download.e …€¦ · Section 1: Present Situation of Stock...
STOCK ENHANCEMENTAND SEA RANCHINGDEVELOPMENTS, PITFALLS
AND OPPORTUNITIES
Second Edition
EDITED BY
K.M. LEBERCenter for Fisheries Enhancement, Mote Marine Laboratory, Florida, USA
S. KITADAFaculty of Marine Science, Tokyo University of Marine Scienceand Technology, Japan
H.L. BLANKENSHIPNorthwest Marine Technology Inc., Washington, USA
T. SVASANDInstitute of Marine Research, Bergen, Norway
BlackwellPublishing
STOCK ENHANCEMENT ANDSEA RANCHING
STOCK ENHANCEMENTAND SEA RANCHINGDEVELOPMENTS, PITFALLS
AND OPPORTUNITIES
Second Edition
EDITED BY
K.M. LEBERCenter for Fisheries Enhancement, Mote Marine Laboratory, Florida, USA
S. KITADAFaculty of Marine Science, Tokyo University of Marine Scienceand Technology, Japan
H.L. BLANKENSHIPNorthwest Marine Technology Inc., Washington, USA
T. SVASANDInstitute of Marine Research, Bergen, Norway
BlackwellPublishing
� 2004 by Blackwell Publishing Ltd
Editorial Offices:
Blackwell Publishing Ltd, 9600 Garsington Road, Oxford OX4 2DQ, UK
Tel: þ44 (0)1865 776868
Blackwell Publishing Professional, 2121 State Avenue, Ames, Iowa 50014-8300, USA
Tel: þ1 515 292 0140
Blackwell Publishing Asia, 550 Swanston Street, Carlton, Victoria 3053, Australia
Tel: þ61 (0)3 8359 1011
The right of the Author to be identified as the Author of this Work has been asserted in accordance with
the Copyright, Designs and Patents Act 1988.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system,
or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or
otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the
prior permission of the publisher.
First published 2004 by Blackwell Publishing Ltd
A catalog record for this title is available from the Library of Congress
ISBN 1–4051–1119–4
A catalogue record for this title is available from the British Library
Set in 10/13pt Times
by Integra Software Services Pvt. Ltd, Pondicherry, India
Printed and bound in Great Britain
by MPG Ltd, Bodmin, Cornwall
The publisher’s policy is to use permanent paper from mills that operate a sustainable forestry policy,
and which has been manufactured from pulp processed using acid-free and elementary chlorine-free
practices. Furthermore, the publisher ensures that the text paper and cover board used have met
acceptable environmental accreditation standards.
For further information on Blackwell Publishing, visit our website:
www.blackwellpublishing.com
Contents
Preface
Section 1: Present Situation of Stock Enhancement
ix
1 Stock Enhancement and Sea Ranching as an Integrated Part of Coastal Zone Management in Norway Erlend Moksness 3
2 Marine Stock Enhancement in the USA: Status, Trends and Needs KennethM.Leber 11
3 Global Warming, Aquaculture, and Commercial Fisheries RichardJ.Beamish and DonaldJ.Noakes 25
4 Stock Enhancement and Sea Ranching in Developing Countries DevinM.Bartley, Abraham Born and Anton Immink 48
Section 2: Seed Quality and Techniques for Effective Stocking 59
5 Why Juvenile Quality and Release Strategies are Important Factors for Success in Stock Enhancement and Sea Ranching Terje Sva sand 61
6 Feats and Defeats in Flatfish Stocking: Determinants for Effective Stocking JosianneG.Støttrup 71
7 Behavioral Approaches to Fish Stock Enhancement: A Practical Review Reiji Masuda 83
8 Lessons for Marine Fish Enhancement: Experiences with Pacific Salmon C.V.W. Mahnken, W.T. Fairgrieve, F.W. Waknitz, D.J. Maynard and H.L. Blankenship 91
9 Releasing Technique in Striped Jack Marine Ranching: Pre-release Acclimation and Presence of Decoys to Improve Recapture Rates Hiroshi Kuwada, Reiji Masuda, Takashi Kobayashi, Takayuki Kogane, Taeko Miyazaki, Keinosuke Imaizumi and Katsumi Tsukamoto 106
Section3: Health ManagementofHatchery Stocks 117
10 Fish Health Management in Seed Production Keiichi Mushiake and Kiyokuni Muroga 119
v
1
vi Contents
Section 4: Methods for Evaluating Stocking Effectiveness 131
11 An Independent Scientific Evaluation of Washington State Salmonid Hatcheries H. Lee Blankenship and MichaelA.Kern 133
12 Experimental Ecological Tests with Stocked Marine Fish JohnM.Miller and CarlJ.Walters 142
13 Examining Genetic Effect Hypotheses of Hatchery Fish on Wild Populations: A Bayesian Approach Shuichi Kitada and Hirohisa Kishino 153
14 Behavior of Ongrown Juvenile Spiny Lobsters, Jasus edwardsii after Reseeding to a Coastal Reef in Tasmania, Australia DavidJ.Mills, Caleb Gardner and Sam Ibbott 168
15 Juvenile Release and Market Size Recapture of the Swimming Crab Portunus trituberculatus (Miers) Marked with Coded Wire Tags Kazutoshi Okamoto 181
16 Evaluation of Stock Enhancement Programs for Masu Salmon in Hokkaido, Northern Japan, by Two-stage Sampling Surveys of Commercial Landings Yasuyuki Miyakoshi, Mitsuhiro Nagata, Kei-ichi Sugiwaka and Shuichi Kitada 187
Section 5: Population Management in Stock Enhancement and Sea Ranching 199
17 Population Management in Stock Enhancement and Sea Ranching Ray Hilborn 201
Section6:ManagementofStocked Populations 211
18 Management of Restocking and Stock Enhancement Programs: The Need for Different Approaches Johann Bell 213
19 Regional Non-profit Corporations – An Institutional Model for Stock Enhancement WilliamW.Smoker 225
20 Management Options for Restocked Trochus Fisheries StevenW.Purcell 233
Section7: Ecological Interactions with Wild Stocks 245
21 Evaluation of the Biological Interaction between Wild and Hatchery Population for Sustainable Fisheries Management of Pacific Salmon Masahide Kaeriyama and RizalitaR.Edpalina 247
Contents vii
22 Risk/Benefit Considerations for Marine Stock Enhancement: A Pacific Salmon Perspective RobinS.Waples and Jonathan Drake 260
23 Effects of Hatchery Releases and Environmental Variation on Wild-stock Productivity: Consequences for Sea Ranching of Pink Salmon in Prince William Sound, Alaska Alex C. Wertheimer, William R. Heard and William W. Smoker 307
Section 8: Genetic Management of Hatchery and Wild Stocks 327
24 Broodstock Management for Stock Enhancement Programs of Marine Fish with Assistance of DNA Marker (a Review) Nobuhiko Taniguchi 329
25 Genetic Studies in Marine Stock Enhancement in Norway KnutE.Jørstad 339
26 Stock Structure and Effective Size of Red Drum (Sciaenops ocellatus) in the Northern Gulf of Mexico and Implications Relative to Stock Enhancement and Recruitment JohnR.Gold 353
27 Natural Selection after Release from a Hatchery Leads to Domestication in Steelhead, Oncorhynchus mykiss Reg Reisenbichler, Steve Rubin, Lisa Wetzel and Steve Phelps 371
Section9: Socio-economicsofStock Enhancement 385
28 Averting Food Crisis in the Twenty-first Century: The Role of Stock Enhancement and Sea Ranching I. Chiu Liao 387
29 The Role of Stock Enhancement in the Management Framework for New Zealand’s Southern Scallop Fishery Kim Drummond 397
Section 10: Case Studies 413
30 Enhancing the European Lobster (Homarus gammarus) Stock at Kvitsøy Islands: Perspectives on Rebuilding Norwegian Stocks A.L. Agnalt, K.E. Jørstad, T. Kristiansen, E. Nøstvold, E. Farestveit, H. Nœss, O.I. Paulsen andT.Sva sand 415
31 The Decline of Global Abalone (Genus Haliotis) Production in the Late Twentieth Century: Is there a Future? JeremyD.Prince 427
32 An Approach to Evaluating the Potential for Stock Enhancement of Brown Tiger Prawns (Penaeus esculentus Haswell) in Exmouth Gulf, Western Australia Neil R. Loneragan, Peter J. Crocos, Roger M. Barnard, Richard R. McCulloch, James W. Penn, Robert D. Ward and Peter C. Rothlisberg 444
viii Contents
33 Stock Enhancement of the Short-spined Sea Urchin Strongylocentrotus intermedius in Hokkaido, Japan Yuichi Sakai, Ken-Ichiro Tajima and Yukio Agatsuma 465
34 Enhancement of Pacific Threadfin (Polydactylus sexfilis) in Hawaii: Interactions between Aquaculture and Fisheries DavidA.Ziemann 477
35 Stock Enhancement of Barramundi, Lates calcarifer (Bloch), in a Coastal River System in Northern Australia: Stocking Strategies, Survival and Benefit-cost D.J. Russell, M.A. Rimmer, A.J. McDougall, S.E. Kistle and W.L. Johnston 490
36 Stocking Effectiveness of Black Rockfish Sebastes schlegeli Released in Yamada Bay Evaluated by a Fish Market Census Masahiro Nakagawa, Hiroyuki Okouchi and Junichi Adachi 501
Section 11: Posters 513
37 A Behavioral Character during the Metamorphosing Stage can Predict the Growth Performance of Juvenile Stage in Japanese Flounder Yoshitaka Sakakura, Katsumi Tsukamoto and Atsushi Hagiwara 515
38 Recapture Rates of Released Hatchlings of Giant Cuttlefish Sepia latimanus Quoy & Gaimard Masakazu Oka, Takashi Yamashita, Shin-Ichi Osumi and Katsuyuki Hamasaki 525
39 Development of a Nursery Reef for Released Juvenile Redspotted Grouper, Epinephelus akaara Shigenobu Okumura, Seiichi Tsumura and Keigo Maruyama 535
40 Release Strategies in Scallop (Pecten maximus) Sea Ranching Vulnerable to Crab Predation Ø. Strand, E.S. Grefsrud, G.A. Haugum, G. Bakke, E. Helland and T.E. Helland 544
Index 556
Preface
Stock enhancement (stocking cultured organisms to replenish or increase abundance
of wild stocks) and sea ranching (stocking for put-grow-and-take food fisheries) are
being recast in the new millennium as more useful fishery-management tools than
ever before. As this book shows, the science needed to develop a reliable stocking
technology is growing rapidly, shepherded by a healthy climate of scientific debate.
The new developments for this century-old fishery-management tool could not be
timelier. With the collapse of many of the world’s fisheries, the replenishment of fish
stocks through techniques such as stocking is of huge importance and interest across the
globe. Fishery management agencies worldwide are struggling with the paradox of trying
to conserve fish stocks and protect them from overfishing, while also meeting an increas-
ing demand for seafood. The steadily increasing demand, owing to population growth
and human health recommendations to increase seafood in the diet, is placing enormous
harvest pressure on wild fish and invertebrate stocks. Exacerbating this situation is
corresponding growth in saltwater sport fishing, degradation of essential fish habitat
from coastal development, and ecological change caused by fishing down the food web.
The alarming consequence of such high demand for seafood is that two-thirds of the
world’s coastal fisheries are now fully exploited, overexploited, or depleted and need to be
rebuilt. Many stocks have become so depleted that they can no longer support fishing.
As world population growth continues, demand for seafood is going to place even
greater pressure on wild fish populations. Clearly we cannot rely, in the future, only
on wild-caught seafood to satisfy demand. Seafood farming must fill the gap in
supply. Already, aquaculture is providing over 25% of the world’s seafood production.
Because of a surge in scientific developments over the past decade that is solving many
production bottlenecks, the marine aquaculture industry is in a phase of rapid growth.
As new culture technologies are developed and advances are made in stocking tech-
nologies, there is great potential to use stocking to help replenish recruitment-limited and
depleted stocks. However, as this book indicates, it is not a simple matter to ensure that
stocking is effective and actually achieves the objectives of a hatchery-release program.
Although stocking marine organisms has been practiced for well over a century, only
within the past two decades have scientists begun to develop the knowledge needed to
guide effective use of hatchery releases. There remain many critical uncertainties about
how to use stocking technology effectively. Consequently, there are few good examples
of clearly successful application of hatchery releases to enhance marine fisheries.
Faced with depleted stocks and the expanding gap in seafood supply, fishery
scientists worldwide are striving to resolve uncertainties about stocking. The result
is a rapidly increasing quantitative knowledge base about the effects and effectiveness
ix
of stocking cultured aquatic organisms to increase fishery production. There have been
many new research developments in this field since the First Symposium on Stock
Enhancement and Sea Ranching was held in Bergen, Norway, in 1997. This book
highlights many of these new achievements as well as opportunities for successful use
of stocking. A general theme is evident – to guide the effective use of stocking, much
research and development is still needed and interactions among stocked organisms and
wild populations must be better understood. Much caution is needed in stock enhance-
ment and sea ranching programs, as there remain many uncertainties about how to use
stocking successfully; there are clear risks to wild stocks from inadequate decisions
about hatchery-release protocols and when, where and how stocking should be used.
As we move from hunting and gathering wild fish stocks toward increased use of
farming to help meet seafood demand, the new production capabilities for species
never grown before is prompting development of new stocking programs worldwide.
The need for more effective stocking strategies is clear. The world must have
sufficient knowledge to use stocking productively in helping to manage fisheries.
If the current trend of increasing research and development of stock enhancement
and sea ranching technologies continues, we believe the number of successful
examples will greatly increase during the next decade.
To help guide future research in the emerging science of stock enhancement and sea
ranching, the principal issues considered in this volume are briefly summarized below.
. There is an evolution in fishery management that reflects a shift in priorities toward
long-term sustainability and a movement away from policies of open access to fishery
resources. Science must play a key role here as we make this shift and deal with a
variety of complex and interacting issues. Responsible stock enhancement requires
new information on rearing techniques, release strategies, disease defense, monitor-
ing, and evaluation of hatchery-release effects (genetic and ecological) on wild stocks.
Harvest rights may be needed to make stocking economically successful. Consider-
ation of ocean productivity is a key aspect of long-term enhancement strategy.
. Research documenting improvements in seed quality shows untapped potential to
increase survival and is a promising area for future improvement in the efficiency of
enhancement. Conditioning fish and invertebrates prior to release will play a major
role here. Much of the progress made in conditioning will result from acclimation
research on behavioral, physiological, developmental, ecological, environmental,
and feeding deficits in newly stocked organisms. Both short- and long-term atten-
tion is needed in field assessments of the effects of conditioning.
. The key issues in health management of hatchery stocks are disease-control
measures in seed production, evaluation of fish health prior to release, and the
presence and level of pathogens in wild stocks. Disease-control measures need
further development. Health control must be a high priority in stock enhance-
ment and sea ranching programs.
. Powerful molecular tools are now available to aid in genetic management of
stocked populations – for monitoring genetic structure of hatchery and wild
x Preface
stocks and monitoring inbreeding; for observing released fish (genetic tags, such
as genetic fingerprinting); for estimating survival and catch contribution. The
theoretical effects of stock enhancement and sea ranching on the fitness of wild
stocks (e.g. domestication, outbreeding depression, inbreeding, adaptability) are
potentially damaging, but difficult to measure. Best-practice guidelines are
needed in all stocking programs.
. Scientists in this field need to advance the theoretical context for selecting release
sites, release microhabitat and the magnitude of stocking; density-dependence and
carrying capacity are key considerations. Production and environmental variables
at release sites are not sufficient information for planning hatchery-releases.
. Improved methods for evaluating stocking effectiveness are needed. Experimen-
tal releases of cultured species, with a link to studying ecological processes, are
key to understanding many of the uncertainties about stocking success. A benign
tag with high information content is essential to evaluate survival and efficiency
of stocking strategies and key ecological issues, such as how to recognize and
incorporate carrying capacity considerations, habitat use, species interactions
and environmental influences in stocking decisions. Good designs are needed
for field studies to test hypotheses about density-dependent effects and genetic
effects of hatchery stocks, leading to better protocols for conserving wild stocks.
Risk benefit considerations must be addressed in a realistic and objective manner
in light of the specific objectives of a stocking program. Adaptive management is
a key to success.
. The competing hypothesis to the premise that large hatchery programs cause a
major increase in total production is the alternative that large hatchery programs
cause a major decline in wild-stock abundance through competitive displacement.
If density-dependence was not present, then populations would grow to infinity.
Thus, adding fish after the density-dependence stage should be a key consider-
ation in stocking programs. Replicates and experimental controls for treatment
effects are needed to evaluate stocking effects. Interactions of hatchery and wild
stocks should be expected and the effectiveness of increasing production with
hatchery releases needs to be tested on a large scale.
. To manage stocked populations effectively, there must be a ‘big-picture’ consider-
ation of the status of wild stocks as well as ecology, both on nursery grounds and
on fishing grounds. Success can be greatly improved when managers of stocking
programs consider institutional arrangements involving all stakeholders, the
social and legal framework, alternative management options, and when those
who will pay for enhancement are identified (fishers, processors, government).
An institutional framework is needed to integrate stocking plans with harvest
regulations, cost-recovery, fisheries management plans, user involvement, and to
identify the role of government.
. Developing countries present special challenges and opportunities. Reasons for
stocking may differ; information is sketchy and generally poor. Appropriate techno-
logy should be transferred or developed, especially in regard to co-management.
Preface xi
. More attention to the socio-economics of stock enhancement and sea ranching is
needed. Stocking has been shown to be economically effective in a few very
successful cases, but very few case studies have actually evaluated economics.
Economic models assume no reduction in growth and survival in natural stocks,
which may not be the case. It is difficult to try to evaluate an appropriate stocking
level. In Japan, though, several unenhanced stocks have much lower production
than enhanced stocks, showing promise for economically successful enhance-
ment. One way to increase value is by moving the location of fisheries closer to
user groups. Economic evaluation of stocking effects on non-target species is
recommended. Culture of non-target species may be needed. Gardening of sessile
organisms may be more effective than stocking them.
. Focus should be placed on how to progress toward predictability. Cooperation on
projects will make maximum progress, and significant programmatic funding is
absolutely essential. Hypothesis tests are needed in different ecosystems; piecemeal
studies will not suffice. For a reliable estimate of the economic potential of stocking
programs, long-term, wide-spatial, and ecosystem viewpoints are necessary.
We regard these as the principal issues today in stock enhancement and sea ranch-
ing. They were identified at the end of the conference in Kobe, Japan, (described
below) by the chairmen of the various topic sessions at the conference and are based
on the key ideas brought forth in each session. The sessions at the conference form
the 11 sections of this book.
We thank Koji Imamura, President of the Japan Sea Farming Association (JASFA),
which was recently integrated with Japan’s Fisheries Research Agency (FRA);
JASFA was reorganized under FRA as the National Center for Stock Enhancement
on October 1st, 2003. In 2002, Mr. Imamura convened and led a very successful
conference in Kobe, Japan, the 2nd International Symposium on Stock Enhancement
and Sea Ranching (SESR), which became the impetus for this book. We appreciate
the financial support provided by the Japan Fisheries Agency and JASFA. We thank
the staff members of JASFA, who worked hard preparing for the symposium.
This book, which contains fully peer-reviewed papers from the symposium, will be
of interest to fish and fisheries biologists, marine and aquatic scientists, managers of
natural resources, environmental biologists, ecologists, conservationists, and aqua-
culture scientists and personnel.
Finally, the editors wish to express their thanks to the SESR Steering Committee
and the SESR International Scientific Committee and to the numerous colleagues
who gave their time to constructively review the manuscripts.
Ken Leber
Shuichi Kitada
Lee Blankenship
Terje Svasand
xii Preface
�������
������ ��� ����� �� ����� �����������
�������
����� ����������� ��� ��� ��������
�� �� ���������� ��� �� ������� ����
���������� �� �����
������ ������������� �� ��� ����� ��� ���� ����� ������ ���� ���������� �� ��� ����� �� �������
� !"#$ %��� � &�'
!"������
�� ���� ���� �������� �� ������� �� ��� �� ���� �� !" ��� �� ����#$��� ��� ��
�����$�' �� �� � ����*��� $ +� �� +�� ��� ��$ �� ���� ��� <�� ������� =�� >
�� ����#��� $ �� + @� ��� ��� �� [#�� �� �\] �^ �� ���$ �� � �� ������' ��
������� =�� ��� ���$��������� + � #� $ ^�� �����*��� ^������ ��$ � �� �����' ��
^��� �� � ��_ + � ��$ ����� �� ������ +�� $ �� �� ���� �* � � � ^��� ������
�#�� �� ���� ���� �*���� �*������ � ����� <������ �� �����> ����� ��� `�����
��$ <(���� � ���> ����� ��� `����� ��$$��� <������ ����� ���������> ��$
��* ��� <������� �������>' ` �����^����� ���#�� �� �$ �^ ��*���� ������� � ��#�� � ��
���� ��� � �#�� �� ������� ��$ ����� <)�������� �� ���> � <*������� ��������>
���+ <����� ���� ��> ���� ���+ <)� �������� ������������> ��+�� � <%�� ��
����� ��> ��$ ��� ��' �_ � �� *��� ]� � ��� � �{��� ^������ �^ ������ ��$ ���#�
�� �� ������� =�� ��_ ���� �� $ |*�� ������� ��$ � ��� $ }"} ��� � �� � �� ����
��$ �� _��# [#��� �� ����� �^ �� ����� ���� ���� ^��� ��' ~� �$$����� �� �
�� �� � � ��� �� ���� �� $ $ ����� �^ �#��� *�*#������ �� �� ������� �� ��' ��
��#���� ��$ � �� ������� ^��� �� ��_ + � ������ $ �� ���� �� ��� ���� ]��
���#���� �_ � �� *��� �! � ���' �� *� � �� �� �$ ^��� ���� ����_��� ��� + �
����#��� $ �� + ���#�$ �! ��� � ^��� ���#���� ��$ ������ ��� �^ �� ����� � ��
������� ��$' ~� ���� + � ����� �� �� ����� ��$ �#**��� � � ����� $ _ ��*� �� �^
�� ��_��� � ��#�� � �� �� ������� =�� �� �� ^#�#� ' �� ���� ���� ������� ��
*��� $ � � � ��� �� ����� ����� � �� ��$ � � �������� �� �� �*���� �^ ����'
�� $�� �� +������#�$ �� ���� ��� �� �� ���� ���� � �������� ��������
<���> ���� ���� *��� + �� � �@@� ��$ �@@"' ���� ��� ���� �� *�����*� ����
���� ��� ��� ���� ��_ �� ����� �� ���_ ��' ���� +� ��� ���� �� ��$ ���� ����
���$����� ���� ����� ��� ���_ �� ^��� �� � �' ��+�� � ��$ ������* <)�����
��+����> ��_ + � �$ ���^� $ �� �� ^���� �* �� � �� ���� � � ����� ����� � ��
����_��� ��$ �� ��� �� �� ���� ��� � +����� ��_��� ������� ���� ^����� ��� �' ����
���*� � ^��#� � �� *� � �� ����� � �� �� ������� =�� #� ��$ *����� �� ^#�#� �^
������� =�� ����� � �� ��$ ��� ����� ����� � �� ��$ � � �������� ��� +
��� ���� $ �� *���� �^ ��'
]
������ �����
�_ � �� *��� �� � ��� ����� ����� � �� ��$ � � �������� �^ ����� �* �� � ��_
|* �� �� $ �� ���� �� $ ��� � �� ���� � �* �� �� +��� �#�+ � �^ �* �� � ����#$ $
��$ ��#���� � ��_��_ $' ����$��$ � *���� ��_ + � *#+���� $ �� _����#� ��*���
�#�� �� � � ���� ����� � �� ��������� +���� �^ ����� � �� ����� �� *��$#�����
^�� ����� � �� �_����� ���� ��*���� ������� ��$ �* ��^�� � � �� |* ��� ���
<� ��� �� �� ��' �@@@ ��$ *� � �� *��� $���>' ~� ������ �� ����_��� ����� $ ���
���� ��� � ��� ��� <�� �$�� �� ��' �@�}> +� � � ����� ���_�� ��$ <(���� � ���> ��
�� ������� =�� �^ ��#�� �� ������' �� ���� �+� ���_ ��� �� � $#� ���#��
^�#��#������ �� �� ������� ��$ ^��� �� ��$ �+���� � ���+� ���#�� �� �$' �� �@"� ��
� � �� � � ������ $ �����#� ��� *���^ �^ �����^����� ^^ �� �� �� ���#�� �� �$
<�_ �� �@"�> �����#�� �� �#�+ � �^ �#_ ��� � �**�� ���� ���� �� $ �� � ��� �� ���
�� �� <���� �� ��' ����>' ��� � |* ��� ���� � � �� � �^ � � ������� ���� $ ����{���
���_� ��_ ����� ���� �� + � ^��� �^ � � ����� ����{��� ���_� �� ��$ $ _ �� �����
<�������� � �� ��' �@@">'
` � � �**����� +� � � ����� �#_ ��� ��$ <����� �� � �� ���$ �@�}> ^��� $ ��
+���� �^ � ���� � ���� ���� *������� ' �� ���� ���� � �������� ��������
<�@@���@@"> |���� $ �� +��������� ��������� �#��$���� ��$ ������� � [#�� {
� ��� ^�� � � � ������� ��$#���� ��$ ����#$ $ ^�#� �* �� � ��� ���� � $�^^ � �� ��^
����� �� <_�� ���$ �� ��' �� *� ��>' �� ��� ����� �* �� � ������� ��$ ��$ ��+�� �
<%�� �� ����� ��> �* �$ �� �� ���� ��^ ���� �� �� ������� =�� ��$ �� � +�
+ ���� �� �� ����� �* �� � �� �� �� �' �� ��� ��� �� + ���� �� �� * ���$�� �* �� � ��
�� ������� =�� ' `������� ������ <���� ���� > �*��� �� �� ��_ �� ��$ �� �^^�*����
�* �$ #* �� ^�_ � ��� �� �� ��� ��_ �' `� ������ �� � � �_ �� ��_ �� ��$ ������ ��
�� �* � � � ^�� ^ $��� ��$ � �#�� �^� � �� �� ^�#� � ��� ^�� �*������' �� �������
=�� �� #� $ ^�� � ����� $ ��� $#���� ��������� ���� ^��� ��$ +��� �� �� ��_ �' ��
`����� ���� <���������� �������> �* �$ ���� �^ �� �� ��_ � �� ��� � �� ����� �� ������
��� _ � � �_ �� ��� � ���#���� ��$ �* �$ ]��}� $��� _ �� �#�� � �� �� �������
=�� ' �#���� ���� * ���$ �� � |* �� �� �� �� ���#�� � ���� ���� �� ' �� *��{
����� ��� + � _��#�� $ +� _�� ���$ �� ��' <�� *� ��> ��$ �� ���� � �#��� ��$����
���� _�������� �� � �#�� ��� ��$ �� � � �� � ��$ ����� $ ^^ �� �� �� ����� ^��� �� �'
���� ��$ ��$ ��+�� � ��#�$ ��_ � ^#�#� *�� ����� �^ �#_ ��� *��$#����� ���� ��
� $#� $ �����^������� <����� �� � ��� �@@" ����� �� �� ��' �@@�>' ��� �� �$ �^
�� *������� � � �������� � � ���� ����_��� � ��_ + � ����� $ �� ��+�� � ��$
$ _ ��*� �� �^ �� +����� �#���_����� �^ ������*� <)����� ��+����>' `� � $�� ��
� �#�� �^ �� *������� �� ���� ���� ������� �� $#���� �� �*���� �^ ����
*��� $ � � � ����� ����� � �� ��� ��$ �� � +� �* � $ �� �#���_����� �^ ��+�� �
��$ ������* �� �� ������� =�� $ ^�� $ �� �� �� � ����*��� $ +� �� +�� ��� ��$
�� ���� ��� '
�_ ���� �� ������� =�� � *� � ��� � ����� * �� ���� �^ �� ���+ �� �#�^�� +#� ��
������ *��$#���_ ��$ ��� � ���� +��{$�_ ����� <������=� �� ��' �@@">' �� � �� ��
���� �� $ ��� ����� ����$��$ �� ��*��_ ������� =�� ����� � �� <���> ���� ��
} ) ����� �������� ���/ 0����������
���� ���� �� �+���� �� �*����� ����{� �� #����=����� �^ �� ������� =�� ' �� $ ������
��$ ���#�$ + +�� $ �� ����� $� �^ �� $�^^ � �� ������ �� ��$ �� �� ����+������
<��� � ����>' �� ������� =�� �� ������ �������� � _ ��� $�^^ � �� ������ �� �����
� �������� �^ �� ��� �� ��$ ��_ �� �� �� � �^ ������� @� ��� ���' �� �� � ���$� +���
* ���� �� ��$ * ���$���� ��_��� � ��#�� �' `���� �� ���� � * ���$���� ^��� ������
�� �� ���� ���� �*���� �*������ � ����� <������ �� �����> ��$ �� ����� ���
`����� ��$' ���� �� �* �� � #� �� ������� =�� ^�� �*������ ��$ *����� �� � �#�� ��
�� � ^�� �� �� �^^�*����' �� +������ �^ �� ���� ���� �*���� �*������ � �����
�� � �� ����� �� �� ��� ��|��#� [#��� ������ ��� �' �� ����� _��# ^��� ��
^��� �� ��$ �[#��#��#� �� � ���+�� $ � *� � ��� ��� ���� �]'� +������ �^ �����
������ �[#��#��#� ������+#� � ������ !��' ` � � �� _��#����� �^ �� ^#�#�
*�� ����� ��$���� � ���� �� _��# ��� + ���� �� $ +� ��� ���� � � ��� � ������
�� � |� ]� � ��� <`���' �@@@>' ~���#$ $ �� �� ������ �^ ^#�#� *�� ����� �� ��
$ _ ��*� �� �^ �[#��#��#� ��$ ^��� �� � �� � � ���' ~ ��� � ����� ����� � ��
��$ � � �������� �� �� �^ �� ����� �� � ��� �#�� � ����' ~ ���� ^��#� �� ���
*�� ����� �� ��� <�> ���� �� �� �$ ^��� ��� ������� ^��� �� <�> �#����� �� $ _ ��*
��#���� ^������ ��$ <]> ���� �� ^��� +������ +� ��+���� � ���������'
������� #��� ����������$ ����� ����������� ��� ��� ��������
�� ������ =�� � *� � ��� � ���� ��$ $�_ �� �� � �^ ���#��� ���$ �� ��$ �������
*����+����� � � �#����� �� ��*��_��� [#����� �^ ��^ ��$ �������� ����� ������ �' ~�
������ �� � �� �� �� ��� � ��#���� � �� � �� �� ���� �� $ ��� ����� �� �� *� ��#�
�� ��$ #� �^ �� ������� =�� ' �� *� ��#� �� �� ������� =�� $# �� �#���
����_��� �� �� � �#��� $ ^� ����� � ^��� �� �� ����� �_����� �� �� � $#����� �� �_���{
�+� ��+����� ^�� ��_��� � ��#�� � #���*�������� ��|�� *���#���� ��$ �_ �{^������
��_ ���� �� $ �_ � �� � ��� ��$ �� |* �� $ �� ���� �� _ � ��� �� ��
������ � ���' �� #� �� �� ����� ^��� �����*��� �� ���� ����� ^������ ^���
�[#��#��#� ��$ ��$#���� ��$ ^��� � �� �����' �� ���^����� �� ���� + �� �
^��� �� � ��$ �[#��#��#� ��$ ���� �_����� ��$ ��������� |*��������� <^��� ��
�[#��#��#� ��$ ��� � #� ��>' �� +����� ��� �^ �� � ���^����� �� �� #� �^ �� �� �
������ �� ������� =�� ' �� ���� � �� �� � +����� $ *��|�� + �� � #� ��$
*��� �����' �� $�� ����� $ $��� ��$ ��^�������� �� �_����+� �� �� �+#�$���
��$ ����� �� �+#�$��� �^ ���� �* �� � ����+����� �� ������� =�� ' �� �������
=�� ��$ ��� ��_��� � ��#�� � �� � ���*� | ���# ��$ �� �� �� �� ����� � ��' ��
����� �� ^�� �� ^#�#� �� �� ���� �_����� �^ � ����� ��$ � ��{^#��������� �������
������ �� �� *��_�$ +��� ���$� ��$ � �_�� � �� �#������ �� �� ^#�#� ' �� ���� �
�� � �� _��#����� ���� �� ��� ���� ����� $� �^ ��_��� � ��#�� � ���� �#������+� ��$
�������� ���'
���� �� |� *���� �^ �� � � �� � �^ ��$ ��$ ��+�� � ���_� ����� ����� � ��
��$ � � �������� �� ������ ��_ ��� + � ��� � + ���$ �� |* ��� ���� ���� �'
�� ���� � ���� ^�� ���� �� ���� �� � �� � ���$����� �^ ^� ��� �� �� �� ������� =��
������ ��� ���������� �� � &�' !
��$ ����� $ � ��������� �� �� ^��� ��' ���� ���_ $� <�@@@> $���#�� � � _ ��� ���^�����
���� ���� ���� �� � ����� ����� � �� ��$ � � �������� �� �����$#� $ �� � * �{
��� �� +���� �� ������' ��� �$_�� �� ���� ���� �� � ����{� �� *��� �� ��$ �^ � � �
��� �� � � �������� �� �����$#� $ �� ��*� � ������� �^ �� ���#�$ + $�� �� * +�
�� *' ���� <�@@@> �� �� ��� � ���$ ��_ � � ����$��$ *���* ���_ �� ��*� � �������
�^ ����� ����� � �� ��$ � � �������� ���� �* ���� � ^ � �� �� ��*�� ��$ ������'
~� ��� �*����� �� � ��� ����� �� � �� �� ���� �� ����� �� �#����� ��$ ���� ��
������� ^��� �� �' � ���� �������� �*����= � �� ��*������ ���� �� � ����� �� �
���#�$ ��� ������ � �������� ���'
% � �� ����������
���� ����������
�� �#��* �� ��+�� � ����� �� � ���$ |��*� �^ ��� �� ���� + �� _ �� � �� �
*�� ����� ^�� ^#�#� � � ��������' �� ��+�� � ^��� �� �� ������ ����� $ ���#�$ �"��
��$ ���#�� ���$���� ��_ ���� _��� $ + �� � ]�� ��$ ��� �' ���� �� �$ �^ ��
�@��� �� ����� � ���� �� $ ��$ � ��� $ �]�� � �� �@]�' ���� �@}! �� �@�� ����� �
� � ��� ���� ��� � � ����' ` � ����_ �� �$ ����� $ ��$ ���� $ #���� �� �@���
<���_�� � �_ �� �@��>' ��� �� � �� �^^����� ����� � ��_ + � �+�#� ]� � � ����
[#������ ]']� �^ �� ��|��#� �� �$ ��$ !� �^ �� �_ ��� �� �$ �� �� *� _��#�
* ���$' �� ����� � �� � ��������� �^ ��+�� � ������ ����� �� ��#�� �� ��$ � �� ��
����� �^ ������ ��� + � +�� $ �� ���� $ � ����� ��$ �����#� � ��� ��= <��>'
��+�� �� � ��� �� �� ^�#� �� ��| � ���' � � �� $ ������� � � �� + ���_ �� $
������ �! � ��� �^ �� � � �� ' �� � � ��� _� � �� ���� �� � �#������ ���#�$ + _ �
��� ������ � �� �� ^#�#� ���� �� ���� �+� ���_ �� ���� �� �� ^#�#� �� �$ �^
�� ^��� ��'
�� � � �� � �^ ��+�� � �� �� ���� ���� � �������� �������� ��$ ��� ������
<�> � � �� � �^ �#_ ��� � ^�� � � �������� ��$ <�> � � �� � �� ���+������� ����
������ � ����� � �� �� ����� �_ �{^��� $ ������' �� ���� �����#���� ^��� ��
*������� <_�� ���$ �� ��' �� *� ��> �� ���� �� �� *����+� �� ���� �� �� �+#�$��� �^
��+�� � +� � � ����� �#_ ��� � ����� ���� �� �� �� � � � �� $ ��$ �� � � �� $
�#_ ��� � $� ��� � *��� ���$ ��+�� � +#� � *� � �� �� �$$����� �� �� ����� �����'
`� �� ���� ���� ������� �� *��� $ �� � � ����� ����� � �� ��� �� �* � $ �
� � �**����� �� �����#��#� ��$ � ���������� �� �* � ��� �� �� ������� �� �� ^��
^������' �^ �� ^�#� �* �� � ����#$ $ �� �� ���� ���� � �������� ��������
<�@@���@@"> ��+�� � ��� �� ���� *�������� �* �� � ^��� �� ��������� *���� �^
_� � <����� �� �� ��' �@@�>' ��^^ � �� ^��� ���� �^ �� ^�� ^��� � ���� ��_ �_ �
���� � $������ � ��+�� �� ���� �� � ����� $ �� � �� ���� �� �� � ��_ � ��� $' ���
�* �� � ��_ + � �$ ���^� $ �� ���� ���� ���� �^ ���� � � ^��� �^ �����#��#� ��+�� �
��$ ������* <)����� ��+����> +��� #���� �� � �^���� $#���� �� �� ������� ���� ' ��
+ ��_��_ $ �� ���� � � ^��� �^ �����#��#� � ��� �� �� � $ $ ^��� �� �#������� �
� ) ����� �������� ���/ 0����������
�� #� � $ ^�� $ �� �' `����$��� �� ���� � � ��� ���� ���� ��� ��_ � ��� �� ��$
� � �� �#_ ��� � ���� �� �* ��^�� �� � �� ����� $ �� ���_ �� ^��� ���� �� �' ���� ��
� � �� ���� ����� ��� + ��#� �^ � ����{��� ���+���� $ ���$����� ��#�$ ��_
^��� $ ����� � ����� $ +� � _ �� �* ��^�� ����������' ~� �#�� + �$$ $ ���� ^�� ^��� �
��$ ��� �� ��� ����� + ��#��� �� � ��� �� $ �� � ���� ��+�� �� ��$\�� ������*� ��
*��� �� $' `���� � � � $�� ����� �� ���� ��_ ��� ���� ����� � �� � ��������� �^
��+�� � ���� �� ���� � + ^^ ���_ �� � ��� �� $ �� � +#� ���� + �� � �*����+����� �^
�� ��� �� ���$ �' ~^ �� � � �������� �^ ��+�� � �� �#�� ��^#� �� �$$ $ _��# ^�� ���
���� �� �^ ��� � ���� [#�� �**��|���� �� �} �������'
�� � �� � _ ��� ���� ���' �� ��� �� ���$ �� ����� ��� �� �*����= �� �#����
�^ �� �� ����_���' �� �**����� ��#�$ + +� �*����=��� �� ��+���� ^�� ��+�� � +�
+��� #�$ ���� � |*������ ��$ �� ����� �^ ����� �� �� ��$ �� � +� �������� ��
��+���� ��$ $ ���$��� �� ��+���� ^�� ��� � �* �� �' ��+���� ��� ���� + ����� $ +�
�$$��� +�� #�$ ���� � ������#�����' ���� ��� �� �� *��+� �� ^�� ���� ����� ^���{
�� �' ~^ #� � ���^����� �� ���_ $ ��$ ��� �� ���$ �� ���� � �* �� ^�� �� ���#���
��+���� �� � ���#�$ + � ^#�#� *�� ����� ^�� � �����^����� ���� �� �� ���#�� �� �$
^��� �� ��+�� � ^��� �� �� ������' �����* �$ ���^� $ �� �� ��� � �* �� � ^�� � �
�������� ���� ��_ � ^#�#� *�� ����� �� � ��' ��� ����� $� �� � $ $ � ���$���
�#_ ��� *��$#����� ��$ �� � �^���� �#���_����� ���� '
1� ��� ������
�� ������� =�� ��� ������ + � �� ��*������ �� � ^�� ����� ���� ����� ^��� �� �
��$ ���� ��� ^��� �� �#**��� �� �� $���� *��� �� ����� ' � �� ������� ^��� �� � ��_
�� ��$ �� ��� � � *��� $ �� ���� ���#* ��$ ����� � � � ���#* �� ��#���� ^��� ��
��� + � �$$ $' �� ���� � ���#* �� $ ^�� $ �� ���{����+������ ^������ �� �������
��� ��' ~� �� � �� ������� ^��� �� �� � �� �� ��= ����� �� �� ��$ �� ���� ����������
+ ��� �� ���#�� �^ � �� * ����� $ ����� �� �� � ��|��#� ��� � ^������ � �� ]��
����� ��$ �� *��� �� ���*�' <�� � � ���������� �� ��� ����� $ �� ��$ ���� '> ~� ��
��#���� ^��� �� ���� ���${� �$ ����� �� ����� $' ���� #� � ���#* �� ��� ����� $ �� � �
�#� ^�| $ [#�*� ��' �� |* �� �� �� ��� � ��#���� � �� ���� �^ �� �� �$ ^��� ��#����
^��� �� $ ���� � �� � ��� � _ � ���� #� � ���#* ��_ � �� �� �� �� � �� � �� ���� �
����� �^ ^������ �#�� ��' ` � � �� ��_ ��������� <���� ���_ $� � �#�^^ ����> ���{
��� $ ���� �**��|���� �� �!� ��� * ����� *������*�� $ �� ��#���� ^������ �� ������
$#���� �� ����\���� � ���� ��$ �� ���#�� ���� �� �� ���� ���#* ��� + � ���
���� ]�� $#���� �� *��� �! � ���' �� �� �$ ^��� ���� ^��� �� ��� �**��|���� ��
�! ��� � $#���� �� ���� � ���� ��$ ��� �^ �� ����� � � � ��$' ~� ����� + |* �� $
���� �� ���� �� ����� ������# ^�� ��� ��� � ��� ��$ �� ^^ �� �� �� ����� ��$
������ �� $�^^��#�� �� ������ '
�� � � ���� �� ��$ �� �� ���� ���� � �������� �������� ��� �����^�����
��$ ���� *��� �� � _ ��� ��������� ����� �� �������� ' �� ���� � �#��� ^��� ��
��_ ���������� ��_ + � � *��� $ +� _�� ���$ �� ��' <����> ��$ *��� �^ �� �� �����#{
���� �� ���� � � �� $ �#��#� $ ��$ �$�*� � �� �� �� ���#��� �_����� �� ��$ �� �
������ ��� ���������� �� � &�' "
���� ������� ������ ��� � ��$ � � �� �� ��� *� � �� �� ���$ ��$ �� �� ��� �� �'
�� � ��*�#� ��� _��� $ + �� � � ��$ ]�� $ * �$��� �� �� � ��� ��$ ��= ��
� � �� ' �� � � �� $ ��$ ���� $ �� �� � � �� $ �� �' �� �*����� ��= �^ � �#_ ���
��$ ^�� � � �� �� + �� � �� ��$ ]� �� <_�� ���$ �� ��' �� *� ��> � �#����� �� ���
���� !� � �#�� ��� ' ~� �$$����� �� �������� ��*����� ��$ *��$#����� ��*����� ^��
��$ ������ � ��_ � �� � ��� ����� �����^������� ^��� � �� �� � ��' `� *� � �� �� �
�� �� ���$ � ���$� �_����+� �� *� $��� �#�� ����� �' �� � ���� �����#$ $ ����
���� �� $ ^������ *� ��#� �� ����� ��$ ������ $# �� � �� ������� ��$ ��#���� ^������
��#�$ ��� � � �� � � ��� �� ���� �� �� ���������� �� ��#���� ^������'
� �������� �^ ��$ ���� �� ���� �+� ���_ �� �#����� �� ��#���� ^������ ��#�$ +
^����� $ +� �����$#���� � ^������ ^ [#�� �� ��� * � * ���� * � � �� ��$ ��#�$
� �#�� �� �� ���#�� ����� �^ ��! �������' ~^ ���� ^ �� #� $ �� *��$#� ��$ �#_ ��� �
<*��$#����� ���� �^ �� * � ^���> � ����� �#�+ � �^ �! ������� �#_ ��� � ��#�$ +
*��$#� $ ^�� � � �� ' `� *� � �� �� |*��������� �� ��� � �_� �� �� ����� ��$
<_�� ���$ �� ��' �� *� ��> ��$ �� � �� � � $ �� �����$#� � � � ��������� ���� ����
���${� �$ ����� � ���#�$ + ����� $ �� +��� � �� ������� ��$ ��#���� ^��� �� ��$ ��$
� �� ���� � �� ���#�$ + � � �� $ +��� ���� �� � �' �|* ����� � � �#�� ��� [#�� ��
��� �^ ��$ ��� ���� � �� �� ���� �� �� �� �$ ���� [#�� �**��|���� �� ]��� � ��
��� �^ �� *� � �� �� �$ �� �� ��#���� ^������'
%�2���� ��� ����
�� � �* ^�� �� <3����� �� �'�� 2 ���> ����� �� ���� ���� ����� �� � _ �� *��$#��{
�_ ������ � ���� �� ���#�� *��$#����� + �� � � ��$ � �� $�� ���� � ��� � ����
<���#� �� ��' �@@!>' �� � �* ^�� �� ��� �� �������� $ ^�#�� ���� �� �_ ��� $ ����� �^
������ ���� ��������� * � *���� � *� � ����� �]� =��*������� �* �� � <������� �� ��'
�� *� *'>' �� � �� *� � ^�� � ���� � �#�+ � �^ ^��� ��$ � � +��$� ��$ �� �$$����� ��
� �* ^�� �� *��_�$ � ���$ �� �� � ^�� � ���� � �#�+ � �^ ���������' �#���� �� *���
]� � ��� �� �� ����� �� ����� �� ����� �^ ������ ��_ |* �� �� $ ���� � $#����� �^
�� � �* ^�� �� $# �� *� $����� +� � � #������ <�� ��'����� ��� � �2���������>
��$ �� ���#����� � �� �� + * ���� �� <��� � �@@!>' ������ � *���� ��_ + �
��$ ^��� ��� � ��#���� � <���� �� �@"! #������ �� ��' �� *� ��>' �� � �#���
��_ �����^����� ��*��� �� �� ������� ^��� �� ����� $ �� �� � �� �� �� �� ������
<�' ������� ���� * ��' ����'> ��$ ��*�� <#������ �� ��' �� *� ��>' � ��������� �^ � �
#����� �#�+� ��� ��� + ��#� $ +� ���� �� $ *������ {� ��� $ ��������� <��� � �@@�>�
��� _ � �� ����{� �� ^^ �� �� �� � �* ^�� �� �� [# ����� $' �� * ���� �� ���#{
����� ��� + � |*���� $ +� �� ^��� ���� � � #������ $� ��� ��_ ���* ������ ��
*� $����� �� �� �� � <���� ����� �@��>' ~� ��� + � � � ����� ��� *� $ ���� �� ����
��� �� � ���� �� � �* ^�� �� �� �#�� �� �� �� �� ������� �� �+#�$��� �^ � � #������'
#������ <�� *� ��> ��� �#�� �� $ � $#���� �� ���=��� *� ��#� ^��� � � #������
����� �� ��#��� �� ����� �^ ������$� ��*�� +� #���� ^ �� � �� ���� ����� ��_
_ ������ +� #���� ����� � +����� �� ���� �' ~� ������ �#�� � ���$� ��_ ���
+ � _��#�� $ ��� _ � ����� ����� � �� ��� + � �#�� �� $ �� �� �**�����
� ) ����� �������� ���/ 0����������
<�' ������� ���� * ��' ����'>' ������ ���^ ^��� <*�� ������ �����> ��_ + �
�$ ���^� $ �� � *�� ����� *� $���� �^ �� � � #������ <��� � � ���� �@@}>' ~�
��+������� |* ��� ��� � ���^ ^��� ��� �� + �� � ] ��$ } � � #������ $����
<� �� ��� ��� � � ���� �@@�>' �� ���� ����� �� �+#�$��� �^ ���^ ^��� �� �^^ �� $
�� �� +� � � ����� �#��#� $ ^��� �� �� + �� _ $ ���� �^ �� �+#�$��� ��$ ��= ���*��{
����� �� ����� �� ���^ ^��� ����� � $#� �� �+#�$��� �^ � � #������' �� $ ����� �^
� � #������ ��� + � ������ $ �� _��� + �� � }! ��$ "! ��$�_�$#��� ��� <��� �
�@@!>' ��*� ����#������� ���� �� ���� ��� �! ��� ���^ ^��� * � $�� �� �� ��� � �
#������ ������ �� �� � �^ ���� ��' �� � � ����� ��� ��� ^��� $ ���^ ^��� �� ��= ����
�^ ��� �� �� *�� ����� �� ���� �#�� � �#�+ � �^ ���^ ^��� ��#�$ �� ��� � � #������
������ �� �� � �^ � ���� �� $����' �� *��$#����� ���� �^ ��� ��� ���^ ^��� <��� ��>
���� + �**��|���� �� �]"! ���' ��� �#�� �� ����_��� �� + �#�� ��^#� �� ^������ ��
���^ ^��� �#�� + ���** $ ��$ �� �� � ���#�$ ��� ���$ ��� ���#��� *� $���� �^ ���^
^���' #�� �� ����_��� � $� �� + $��#� �� $' ~^ � � ��� ��� �+�#� ��� �* �� �
��� ���� � ����� #� ����� ����� � �� ^�� � ����� ��* � �^ ��+���� � ���������'
� ���$��� �� � �* ^�� �� � ��������� �� �_����� ���� + � ^��� �� �+_��#�' ��
� �#��� ���� + � �����^����� ���� �� �� +������ ��$ �* �� � $�_ �����' ` � ����� � �*
^�� �� ���� ^#������ �� �� ��*������ �#�� �� �� � ^�� ^�� ^��� � �#�� �� ��$' `� �_ ����
� �#�� ���� + � ���� � ^�#�� ���� ���� �� $ ^�� ^��� +������ �_����+� ^�� ���_ ��'
����� ����
���� ����� � �� ��$ � � �������� ��_ � ^#�#� *�� ����� ������ �� ���� ����
������� =�� ' `$$ $ _��# ��� + �� �� $ ������ ��� �� ��� +����� �#��#� �^
��+�� � ��$ ������*� � � �� � �^ �#_ ��� ��$ �� �#����� ��#���� ^��� ��� ��$ ��+����
� ��������� +� ���� ����� +������ ����#�� � � �� � �^ � � ����� *� $���� �#�� ��
���^ ^��� �� *� � �� � � #����� ������ $ ����� $ � �* ^�� ���'
����������
`���' <�@@@> � ��� ��������� 4� ���/������ ����� %��2 �/' � ��* ���_������ #���+ �$ � �_ ��+ �$�{
��#** #�$ � ���$ �� � ���` �� ���'
������� �' ���� �� � �'`' ���$ ���#� �'�' � ���� {�� �� � �' <�� *� *'> * �� � $�����+#���� ��$
��+���� |*��������� �^ ^�#�� �������� $ �� � �* <3����� �� �'�� 2 ���> �� �� ���� ���� �����'
������=� �' $�`�� �' $ ����� �' ���+ � ' ������ �' ������ �' ���+#�� ' �� � '
��� ��� �' ���# �� �' ������ �' #���� �' � _�� $ � � �� �' <�@@"> �� _��# �^ �� ����$��
������ � � �_�� � ��$ ���#��� ��*����' ���� � &'( �!]����'
��� � �'�' <�@@�> �����*�������� *�=����� $�� �� � � *�� ����� � ������� ^�� �� � ��������� �^ � �
#����� �#�+� ��� �� ����� �� ������' �� 5 6��' ) }�@�}"�'
��� � �'�' <�@@!> � �#�� �� $ ���#���_ ���=��� �^ �#�� ��������� �����#� � �* ^�� ��� +� �� � � �
#������ �� � ��^���$ � ����� �� ������' �� 5 0��5 ) �5 �� ' *& @!����'
��� � �'�' � ���� '�' <�@@�> �#�������� � �*��� �^ �� *� $����� `� ����� ��+�� � %�� ��
��� ������ <���� {�$���$�> ��$ `������� ���^^��� *�� ������ ����� <�'> �� ���� ����� �#�+ �� �^
�� �� � � � #����� �� ��'����� ��� � �2��������� <�#�� �>' 75 0+�5 �� 5 6��5 0��' +/ �@����'
������ ��� ���������� �� � &�' @
��� � �'�' � ���� '�' <�@@}> �|* ��� ���� �������� �^ ^������ ��^�# ����� �� ���� ������ + ��_��#�
�^ �� �� � � � #����� �� ��'����� ��� � �2��������� <�#�� �>' 75 0+�5 �� 5 6��5 0��' (;
��"����'
���� ���_ $� `' <�@@@> ����� � �� �^ ����� $ ������� ������ ������� ��$ ��� �� ���# �' ~�� ���/
0���������� ��� ��� �������� < $� �'�' ��� �� �' ����� �� � �' _�� ���$> **' }@]�!��' �������
� �� ����� �|^��$'
���� ���_ $� `' � �#�^^ ~' <����> ���� ��� ���' �� ����$�� �#����^��� � ���� ' ��� � � ��� � &�����
����� ���8� *�������� ����' ~� ���� ����'
���� ����� �'�' <�@��> ��*#������ +������ �^ �� � � � #����� �� ����� +��� ��' �� 5 0��5 ) �5 �� '
&& �@!�]��'
��� �� �'�' ����� �� �' � _�� ���$ �' < $�> <�@@@> ���/ 0���������� ��� ��� ��������' �������
� �� ����� �|^��$'
�������� � �'' ������$ '�' ��� ��� �' ��#�� � �'~' � _�� ���$ �' <�@@"> ������� � �^ ���_�� �#�_�_��
�^ ��$ <(���� � ��� �'> +� � � �� � �^ � � ������� ���� $ ����{��� ���_� ' 75 ����5 6��' +<#**� {
� �� `> ��}���]'
#������ �' ���� �' � �� �� �' ����� ���� � ���$� ^�� � �* ^�� �� $ _ ��*� �� �� �� �+��� �
���#�$� ����� �� ��#��� �� ����� �^ ������$� ��*��' ����5 ���' ;' <�� *� ��>'
���� �� �'�' <�@"!> �� �� � ���������* + �� � ����� *����� ��$ � � #������' 9����� 5 �� 5 6��5
*��5 ���' & ��]����'
���� �' <�@@@> ��� ��� ����� ����� � �� ��$ � � �������� � �* �#����� ��$ ���� �� ������� ^��� �� ��
~�� ���/ 0���������� ��� ��� �������� < $� �'�' ��� �� �' ����� �� � �' _�� ���$> **' �]���}@'
������� � �� ����� �|^��$'
����� �� �' � �� ���$ �' <�@�}> ������� ��$ � � �� |* ��� ��� �� �{���#* ������� ��$ <(����
� ��� �'> � �� $ �� �� �#�$��� +����' ~�� 1�� ) ������� �� ��$#� ����#� 3' < $� �' ����
�'' ���� ��� � �' ����� �� � �' �� �$��> **' "�"�"@}' ���$ _�� � ��**���� � '
����� �� �' � ��� �' <�@@"> ���_��#��#� �^ ����� ^��� ^�� � � �������� *#�*�� �� �� �� *��^���+� �
*:������� � ++ ]}��]!]'
����� �� �' ��� �' � _�� $ � � � � �' <�@@�> ���^���+����� �������� �^ � � �������� ���� `�������
����� <���� ���� > `����� ���� <���������� �������> ��$ �#��* �� ��+�� � <%�� �� ����� ��> ��
������' 6���5 �� 5 ���' ;* ��@��@@'
��� � '�' <����> �$#������ ^�� ��_ ����� �^ ������� ������ ��� �� $�� ������ �^ �� ����� �� ' 9����
; ������ ������' )& ]]��]}�'
���_�� �'�' � �_ �� ' <�@��> ` ����� ��� ��� �� �^ ��+�� � <%�� �� ����� ��> �� �� ���� ����
��� ���� �����' ���������� ���� ��� �� & ����'
���#� ' �� $���� � ' �# � �� �' � � �� �'�' <�@@!> ���������� ��#$� � �^ �� � �* 3����� ��
�'�� 2 ��� <�#�� �#�> ����� �� ������' ~�� 0���' �< �� ��� ������ =��� � < $�
�'�' ����$�� �' ��*���� '�' �������$ � �'�' � �����> **' !�!�!]�' ��� _� � �� �� �'�'
���� �'�' ������ � �' � �� �� �'�' ������ � �'�' ���� ��� � �'' �� �$�� �' � �_ �� '
<����> ` � ��#�� �^ ����*#������ � ��#��� �� �� ������� ��$ *�*#�������� �� ���$ _�� � |* �� �� '
��0� �� 5 ���5 �'��' *+ }���}�!'
�� �$�� �' ���� �' ���� ��� � �'' � ����� �� �' <�@�}> �� ��$ ����� �� �� ���$ _�� � �
+������#�$ ��$ � ����� �' ~�� 1�� ) ������� �� ��$#� ����#� 3' < $� �' ���� �'' ���� ��� �
�' ����� �� � �' �� �$��> **' �"�}!' ���$ _�� � ��**���� � '
_�� ���$ �' `����� `'{�' ����� � �' � ��+ �� � �' � ���+� � �'�' `� ��� ���� $ $ _ ��*� ��
*������� ^�� ����� ��������� �� ���� ���� |��*� ' �*9 ����5 1���5 )��' <�� *� ��>'
_�� ���$ �' �������� � �'' � $ �� � �' � � ��_�� � `'�' ��� �� � �' ��_$�� �' � ��$�_ $� �'
<����> �� ����� � �� �^ ��$ ������' ���� ����' �"]���]'
�_ �� ' <�@"�> ��#��#����� �� � ��{����� ��� ���� �^ ��$ ��$ *������ �� ��#�� ��� �� ���� ���� �������
��� �� $#���� �@����@�@' ���/�� 5 �/ 5 �� 5 %��>��� �' ; �!�"�'
�� ) ����� �������� ���/ 0����������
Chapter 2
Marine Stock Enhancement in the USA:
Status, Trends and Needs
KENNETH M. LEBERCenter for Fisheries Enhancement, Mote Marine Laboratory, Sarasota, Florida, USA
Abstract
Americans have had a fascination with the idea of stocking to enhance marine
fisheries dating back to the latter part of the nineteenth century. After the first
salmon hatchery in America was established in Maine in the 1870s, the first marine
finfish hatcheries were constructed in Woods Hole and Gloucester, Massachusetts.
The marine hatcheries produced and released into the sea millions of fish fry – cod,
flounder, haddock, pollock. But because only unmarked eggs and yolk-sac larvae
could be released, no indication of success was evident and marine fisheries
enhancement was curtailed in the United States for about 30 years. After the
closure of commercial fisheries for red drum in Texas in the early 1980s, private,
state and Federal funding became available to construct new marine fish hatcheries
there for extensive culture and release of this highly prized sport fish. Over the past
decade or so, new research-oriented marine stocking projects began in several
states: California, Connecticut, Florida, Hawaii, Maryland, Mississippi, New
Hampshire, North Carolina, South Carolina, Texas, Virginia and Washington.
These new programs are placing much greater emphasis on evaluation than ever
before. Marine fisheries enhancement in the US is strongly influenced by new
aquaculture and marking technologies. Culture systems have progressed from
extensive to semi-intensive and intensive rearing systems, and are now moving
toward recirculating systems and sea cages. The research programs typically use
chemical marks, coded wire tags, elastomer tags, and recently, sonic tags and
genetic fingerprinting to identify hatchery animals.
Fisheries enhancement research in the USA is now characterized by field
studies to determine genetic stock identification; comparison of natural levels of
diseases and parasites between hatchery and wild fish; release–recapture studies
to optimize release strategies and document contribution rate; behavioral studies;
ecological studies; use of hydro-acoustics to track movements of hatchery fish
and locate older released fish; increasing interest in evaluation of carrying cap-
acity and its effects on success rate; and a move toward adaptive management,
organization of research groups, and increased networking among scientists.
There is a clear need for better development of a science of fisheries enhancement
11
in order to understand how to achieve a predictable, controlled enhancement
effect. The priority research needs today are evaluation of density-dependent
effects on hatchery-release effect and field evaluation of genetic effects on wild
stocks.
Introduction
Advances in marine aquaculture and stocking techniques have made releases of
hatchery-reared organisms into aquatic ecosystems seem an attractive option for
managing coastal fisheries. But do we understand enough about the effects of stock-
ing to use it effectively? Here I consider the status, trends, and needs of marine stock
enhancement in the United States (US) in order to increase our understanding of this
management option.
The year 1871 was a formative one for fisheries enhancement in the United States. The
first US salmon hatchery was established in Maine, and soon after that the US Congress
funded shore-based marine finfish hatcheries. In addition to Atlantic salmon, cod,
haddock, pollock and flounder were produced, and eggs and yolk-sac fry were stocked
in an effort to replenish diminished fish stocks. A trend had started that set the focus of
US fisheries management for several decades (Richards & Edwards 1986, Blaxter 2000).
In 1938, the US Congress passed the Mitchell Act, amended in 1946, to mitigate in
perpetuity for habitat and salmon runs lost to federal water projects within the Columbia
River watershed (mainly hydro-electric dams) (US FWS 2000). The Mitchell Act
supports 25 major salmon hatcheries, which produce over 70 million smolts annually.
Meanwhile, after 70 years of stocking marine finfish, the US closed its marine
hatcheries, i.e. for organisms that spawn in seawater (Grimes 1995, Blaxter 2000).
Emphasis had been on the magnitude of hatchery production, not on yield per
stocked fish. After 70 years of stocking with no signs of success, the US Bureau of
Commercial Fisheries was still stocking only newly hatched fry when the hatcheries
at Woods Hole (1949) and Gloucester (1953) were closed.
While stocking to enhance marine fisheries was curtailed in the US, anadromous
species stocking programs expanded, particularly for restoring and supplementing
salmonids. The US Congress passed the Anadromous Fish Conservation Act in 1965
(US FWS 2000). This act mostly focused on increasing sportfishing opportunity by
stocking hatchery-reared fish. Over time, support for anadromous enhancement grew
with federal, state, industry and NGO support of US Pacific salmon fisheries, in
support of the large sport and commercial fisheries, much of which were focused in
the Pacific Northwest.
Current US public and private support for stocking Pacific salmon is substantial.
Sources of funding for some of the largest programs are Alaska’s private hatcheries
(�US$25 million); the Mitchell Act (�$13 million); Bonneville Power Company
(�$12 million); the Pacific Northwest Salmon Recovery Program (�$8 million);
Salmon Hatchery Reform (�$5 million); Pacific NW Indian Tribes; US–Canada
12 Present Situation of Stock Enhancement
Pacific Salmon treaty; Dingle Johnson/Wallop-Breaux sport fish restoration tax;
US Fish and Wildlife Service; NGOs & Industry support (US FWS 2000).
Current status of marine fisheries enhancement in the US
There is currently much renewed interest in marine stock enhancement in the US,
following advances in marine aquaculture. Marine aquaculture systems in the US
have progressed from extensive to semi-intensive and intensive rearing systems, and
are now moving toward recirculating systems and sea cages (Stickney & McVey
2002). Several states in the US are researching marine stock enhancement potential.
The research programs typically use chemical marks, coded wire tags, visible implant
elastomer tags and, recently, sonic tags and genetic fingerprinting to identify hatch-
ery animals (e.g. Leber et al. 1995, 1996, Willis et al. 1995, Smith et al. 1997, Blaylock
et al. 2000, Garbor 2001, Fairchild 2002, Bert et al. 2003, Friedlander & Ziemann
2003). Among these programs, only California, Florida, South Carolina and Texas
have state mandates to carry out marine fisheries enhancement, but there are also
well-funded research programs at various state, federal, and private laboratories,
which are designed to develop and test stock-enhancement technology. The states
with the greatest-funded programs among these include:
California Hubbs-Sea World Research Institute, in cooperation with California
Department of Fish and Game, is conducting research on stock enhancement of white
sea bass, California halibut, and rockfish (leader is Don Kent; see Kent et al. 1995).
Connecticut The National Marine Fisheries Service, Northeast Fisheries Science
Center’s Milford Laboratory, is researching bay scallop and tautog stock enhance-
ment (leader is Anthony Calabrese; see Goldberg et al. 2000).
Florida The Florida Fish and Wildlife Conservation Commission, in partnership with
Mote Marine Laboratory, is researching enhancement potential of red drum, common
snook, Gulf of Mexico sturgeon, bay scallops and (MML) red snapper (leaders: Bill
Halstead, Ken Leber, Alan Huff, Bill Arnold; see Willis et al. 1995, Bert et al. 2003).
Hawaii The Oceanic Institute is researching striped mullet, Pacific threadfin, and
red snapper stock enhancement (leader is David Ziemann; see Friedlander &
Ziemann 2003).
Maryland The University of Maryland Biotechnology Institute’s Center of Marine
Biotechnology is evaluating stock enhancement potential of blue crab (leaders are
Yonathan Zohar, Anson Hines; see Zohar & Mylonas 2001).
Mississippi The University of Southern Mississippi College of Marine Sciences,
Gulf Coast Research Laboratory is researching red snapper and blue crab stock
enhancement (leader is Bill Hawkins; see Pruder et al. 1999, Blaylock et al. 2000).
Marine Stock Enhancement in the USA 13
New Hampshire The University of New Hampshire Coastal Marine Laboratory is
researching winter flounder stock enhancement (leader is Hunt Howell; see Fairchild
& Howell 2000).
North Carolina North Carolina State University is researching blue crab and sum-
mer flounder stock enhancement (leader is Dave Eggleston; see Kellison et al. 2002).
South Carolina The South Carolina Department of Natural Resources, Marine
Resources, is researching stock enhancement of red drum, cobia, and black sea bass
(leader is Ted Smith; see Smith et al. 1997).
Texas The Texas Parks and Wildlife agency stocks red drum and spotted seatrout,
and is working to develop culture technology for tarpon. Texas was the first state to
re-establish stocking programs with marine fishes, and pioneered extensive pond
rearing technology for marine fishes in the US (leader is Robert Vega; see
McEachron et al. 1998).
Virginia The Virginia Institute of Marine Science of the College of William and Mary
is evaluating blue crab stock enhancement (leader is Rom Lipscius; see Seitz et al. 2003).
Washington The National Marine Fisheries Service, Northwest Fisheries Science
Center’s Manchester Laboratory, and the Washington Department of Fish and
Wildlife are researching lingcod, Pacific cod, rockfish and salmon stock enhancement
(leader is Conrad Mahnken; see Berejikian et al. 2000).
Marine fisheries enhancement is at an intermediate stage of development in the US
(see discussions in Blankenship & Leber 1995, Hilborn 1998, Leber 1999, 2002,
Blaxter 2000). It is clear by now that many cultured marine fishes will survive and
grow in the wild. The principal question in marine stock enhancement research today
is about identifying whether stocking truly increases fish production and the precau-
tions that are needed to ensure that cultured fish do not simply displace wild fish
without any net increase in total production (Hilborn 1999). Many other critical
uncertainties about stocking also remain unevaluated, e.g. the effectiveness and
efficiency of release strategies, cost-effectiveness, unregulated fishing-effort dynamics,
effects on wild stocks, effects on the ecosystem, sustainable replenishment versus
dependency on stocking, and whether yields achieved from stocking are greater than
yields from the alternatives – sound regulations and habitat management. Clearly,
much research is needed to develop the full potential of stock enhancement in the US.
Trends in fisheries enhancement in the US
Fishery management is undergoing dramatic evolution, as fish population dynamics
become better understood (Walters & Martell 2004). However, owing largely to the
lack of scientific information about interactions of hatchery fish with wild fish, there
14 Present Situation of Stock Enhancement
is much public and scientific debate in the US over stock enhancement. We have
debated for decades the ethical use of fish culture in fisheries management; now the
discussion has moved to the broader societal forum – the environmental community.
Fishery management objectives in the US are mainly determined by public demand.
For decades, the public has supported stocking initiatives. But now the criteria for
the use of cultured species are changing in response to evolving public fishery policy –
i.e. the precautionary principle (FAO 1995). Modern fishery management would ensure
maintenance of natural systems with native biota and optimal biodiversity. The polit-
ical climate among policy makers has shifted toward the greener side, following an
increase in new environmental groups in the US. The end result needs to be a sound
public policy that captures both the social and the economic benefits of renewable
common property fishery resources (Hilborn 1999, Walters & Martell 2004).
In part because of environmental concerns about fish stocking programs (e.g.
Hilborn 1999, Walters & Martell 2004), beginning about the early1990s researchers in
the US joined a worldwide trend toward much greater emphasis on the quantitative
research needed to develop and test stock enhancement theory before launching new
large-scale enhancement projects. New technologies such as coded wire tags, elastomer
tags, chemical, temperature and genetic stock identification, hydro-acoustics, and
aquaculture advances have greatly facilitated research. Much of the emphasis in stock
enhancement programs is now focused on applying a responsible approach to enhance-
ment (as in Cowx 1994, Blankenship & Leber 1995, Munro & Bell 1997).
Today in the US, as in many countries, various research groups are testing marine
stock enhancement impact and effectiveness in quantitative field studies. These include
experimental releases to evaluate survival, optimize release strategies, and deter-
mine the contribution of hatchery fish to fisheries (e.g. Drawbridge et al. 1995, Leber
et al. 1995, 1996, 1997, 1998, Roberts et al. 1995, Willis et al. 1995, Glazer et al. 1997,
Smith et al. 1997, McEachron et al. 1998, Stoner & Glazer 1998, Blaylock et al. 2000,
Fairchild & Howell 2000, Goldberg et al. 2000, 2001, Kellison et al. 2000, 2002, Masuda
& Ziemann 2000, Arnold 2001, Brennan & Leber 2002, Collins et al. 2002, Denson
et al. 2002, Hawkins et al. 2002, Bert et al. 2003, Friedlander & Ziemann 2003,
Brennan et al. in press, Ziemann & Friedlander in press). Many of the new studies
also involve research needed to develop genetic conservation protocols for stocking
(e.g. Campton et al. 1992, Bartley et al. 1995, Tringali & Leber 1999, Garber 2001, Bert
et al. 2003) and comparison of natural levels of diseases and parasites of hatchery and
wild fish (Blaylock et al. 2000, Bert et al. 2003). And studies have begun to examine
density-dependent processes and carrying capacity effects on stocking success and
recruitment of hatchery and wild fish (e.g., Leber et al. 1995, Kellison et al. 2000, 2002).
A clear sign of a more quantitative approach to stock enhancement in the US is the
increase in publications and symposia in this field within the past decade. A computer-
generated Web of Science search of peer-reviewed scientific journals using the
keywords stock enhancement or stocking found 49 references to US studies after 1993,
compared to only 2 US references for all years on record prior to 1993 (dating back
to 1949). US symposiums on stock enhancement reveal increasing emphasis on field
Marine Stock Enhancement in the USA 15
studies designed to test stocking effects – e.g. the American Fisheries Society Sym-
posium 15 (Schramm & Piper 1995); the Mote Symposium on Fisheries Ecology
(Coleman et al. 1998); and the US–Japan Cooperative Program in Natural Resources
(UJNR) Aquaculture Panel’s symposia on stock enhancement (Howell et al. 1998,
Nakamura et al. 2003).
Another sign of the expanding information base is that both Federal and state US
fisheries management agencies are incorporating active adaptive management
(Walters & Hilborn 1978, Hilborn & Walters 1992) as an integral part of the manage-
ment process. There is increasing focus in the US on advancing the scientific back-
ground needed for developing effective enhancement programs prior to conducting
large-scale stocking.
Fisheries enhancement needs in the US
First and foremost – predictable stocking effects
The gains would be great from developing a truly effective and reliable stocking
technology that could rapidly replenish depleted stocks, augment fisheries, and save
stocks that are on the brink of extinction. To achieve this capability, we must address
and solve the many questions that remain about how to ensure stocking objectives
are actually achieved. We must keep the more rapid development of a science of
fisheries enhancement as a top priority. A formidable amount of work is needed to
develop predictable, controlled results from stocking.
For stocking to become a practical fishery-management tool, cost-effective stock-
ing strategies must be clearly determined. To do this, stocking plans are needed with
protocols for critical stocking variables (size-at-release, release site, timing of releases,
release magnitude; e.g. Leber et al. 1996, Leber 1999, Blaxter 2000). And these
factors must be coupled with the tactics deemed necessary to control hatchery stock’s
interactions with wild stocks. Thus, the focus of marine enhancement studies needs to
move beyond evaluating post-release survival, and effects of release strategies on
survival, to new studies of interactions between hatchery and wild stocks.
To understand and control interactions between hatchery and wild stocks, such as
competitive exclusion, predation and cannibalism, genetic and health impacts, lit-
erally years of experimental field studies are needed. As we fill in the gaps in know-
ledge, the results need to be included in multispecies models focused on stocking
effect. The ecosystem models that must be developed for predicting enhancement
impact need to incorporate many ecological factors related to stocking that fishery
scientists and ecologists have not yet addressed.
Field evaluations of genetic effects of stocking must also be done to quantify
genetic impact and consequences. For example, are there threshold levels of out-
breeding depression below which stocks can quickly recover? What degree of genetic
change is detrimental?
16 Present Situation of Stock Enhancement