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Dynamic Changes in Marine Ecosystems: Fishing, Food Webs, and Future Options Dynamic Changes IN MARINE ECOSYSTEMS Fishing, Food Webs, and Future Options Committee on Ecosystem Effects of Fishing: Phase II—Assessments of the Extent of Change and the Implications for Policy Ocean Studies Board Division on Earth and Life Studies NATIONAL RESEARCH COUNCIL OF THE NATIONAL ACADEMIES THE NATIONAL ACADEMIES PRESS Washington, D.C. www.nap.edu
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Dynamic Changes in Marine Ecosystems: Fishing, Food Webs, and Future Options THE NATIONAL ACADEMIES PRESS 500 Fifth Street, N.W. Washington, DC 20001 NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance. This study was supported by Contract/Grant No. DG133R04CQ0009 between the National Academy of Sciences and the National Oceanic and Atmospheric Administration. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the organizations or agencies that provided support for the project. This report is funded in part by a contract from the National Oceanic and Atmospheric Administration. The views expressed herein are those of the author(s) and do not necessarily reflect the views of NOAA or any of its subagencies. International Standard Book Number 0-309-10050-X (Book) International Standard Book Number 0-309-65475-0 (PDF) Library of Congress Catalog Number 2006927390 Cover art by Ray Troll, “North Pacific Marine Life,” © 1986 Additional copies of this report are available from the National Academies Press, 500 Fifth Street, N.W., Lockbox 285, Washington, DC 20055; (800) 624-6242 or (202) 334-3313 (in the Washington metropolitan area); Internet, http://www.nap.edu. Copyright 2006 by the National Academy of Sciences. All rights reserved. Printed in the United States of America
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Dynamic Changes in Marine Ecosystems: Fishing, Food Webs, and Future Options THE NATIONAL ACADEMIES Advisers to the Nation on Science, Engineering, and Medicine The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Wm. A. Wulf is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. Wm. A. Wulf are chair and vice chair, respectively, of the National Research Council. www.national-academies.org
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Dynamic Changes in Marine Ecosystems: Fishing, Food Webs, and Future Options COMMITTEE ON ECOSYSTEM EFFECTS OF FISHING: PHASE II—ASSESSMENTS OF THE EXTENT OF CHANGE AND THE IMPLICATIONS FOR POLICY1 JOHN J. MAGNUSON (Chair), University of Wisconsin, Madison JAMES H. COWAN, JR., Louisiana State University, Baton Rouge LARRY B. CROWDER, Duke University, Beaufort, North Carolina DORINDA G. DALLMEYER, University of Georgia, Athens RICHARD B. DERISO, Inter-American Tropical Tuna Commission, La Jolla, California ROBERT T. PAINE, University of Washington, Seattle ANA M. PARMA, Centro Nacional Patagónico, Chubut, Argentina ANDREW A. ROSENBERG, University of New Hampshire, Durham JAMES E. WILEN, University of California, Davis Staff CHRISTINE BLACKBURN, Program Officer SUSAN PARK, Associate Program Officer NANCY CAPUTO, Research Associate PHILLIP LONG, Program Assistant The work of this committee was overseen by the Ocean Studies Board. 1 The committee and staff biographies are provided in Appendix A.
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Dynamic Changes in Marine Ecosystems: Fishing, Food Webs, and Future Options OCEAN STUDIES BOARD SHIRLEY A. POMPONI (Chair), Harbor Branch Oceanographic Institution, Fort Pierce, Florida LEE G. ANDERSON, University of Delaware, Newark JOHN A. ARMSTRONG, IBM Corporation (retired), Amherst, Massachusetts WHITLOW AU, University of Hawaii at Manoa ROBERT G. BEA, University of California, Berkeley ROBERT DUCE, Texas A&M University, College Station MARY (MISSY) H. FEELEY, ExxonMobil Exploration Company, Houston, Texas HOLLY GREENING, Tampa Bay National Estuary Program, St. Petersburg, Florida DEBRA HERNANDEZ, Hernandez and Company, Isle of Palms, South Carolina CYNTHIA M. JONES, Old Dominion University, Norfolk, Virginia WILLIAM A. KUPERMAN, Scripps Institution of Oceanography, La Jolla, California FRANK E. MULLER-KARGER, University of South Florida, St. Petersburg JOAN OLTMAN-SHAY, NorthWest Research Associates, Inc., Bellevue, Washington ROBERT T. PAINE, University of Washington, Seattle S. GEORGE H. PHILANDER, Princeton University, New Jersey RAYMOND W. SCHMITT, Woods Hole Oceanographic Institution, Massachusetts DANIEL SUMAN, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Florida STEVEN TOMASZESKI, Rear Admiral, U.S. Navy (retired), Fairfax, Virginia ANNE M. TREHU, Oregon State University, Corvallis Staff SUSAN ROBERTS, Director DAN WALKER, Scholar FRANK HALL, Program Officer SUSAN PARK, Associate Program Officer ANDREAS SOHRE, Financial Associate SHIREL SMITH, Administrative Coordinator JODI BOSTROM, Research Associate NANCY CAPUTO, Research Associate SARAH CAPOTE, Senior Program Assistant
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Dynamic Changes in Marine Ecosystems: Fishing, Food Webs, and Future Options Preface Challenges to sustaining the productivity of oceanic and coastal fisheries have become more critical and complex as these fisheries reach the upper limits to ocean harvests. In addition, it is now clear that we are managing interactive and dynamic food webs rather than sets of independent single-species populations. Fisheries products cannot be extracted from the sea without ecosystem effects; even though we all know this, we have not incorporated the consequences of fishing food webs and modifying trophic structure and species interactions into the scientific advice that informs policy and management systems. This insufficiency has come at a cost of collapsed fisheries and unintended consequences. Fisheries influence non-targeted as well as targeted species. Some of the non-targeted species are part of the bycatch, but others have been affected profoundly by the complex interactions in food webs initiated by fisheries that reduce the abundance of their predators or prey. Publicity accompanying the publication of several prominent articles in the scientific literature on the influence of fisheries on apex predatory fishes and on the changing structure of marine food webs generated public concern that the oceans had been “fished out” quite literally. Our committee was charged with the review and evaluation of the current literature (including these high visibility papers) on the impacts of modern fisheries on the composition and productivity of marine ecosystems. After discussions about this assignment with the sponsor at our first committee meeting, it became clear that neither the committee nor the sponsor wanted a detailed peer review or a reanalysis of those scientific reports that attracted so much public attention. Instead, we determined that this study should provide an overview of the topic, including a review of these highly
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Dynamic Changes in Marine Ecosystems: Fishing, Food Webs, and Future Options visible papers in the context of the broader body of literature now available. The report provides an overview of the influence of fisheries on marine food webs and productivity. We were also asked to discuss the relevance of these findings for U.S. fisheries management and to identify areas for future research and analysis. Lastly, we were asked to characterize the stewardship implications of our findings for living marine resources. This report and its findings will challenge scientists and managers to implement new approaches to fisheries policy and management. The committee recognized from the onset that ecosystem effects on fishery productivity include other issues related to water quality and pollution, habitat modifications and loss, land use, invasive species, climatic change, and other factors. These need to be incorporated into an ecosystem-based approach to managing oceans and coasts. Such concerns were not in our charge, and we did not deal with them here. However, these drivers do impact fisheries dynamics and are as important to sustaining fishery productivity as those we do address. We believe that moving from a single-species approach toward a food-web management approach is an important step forward in achieving an ecosystem approach to fisheries management. In this new context for fisheries management, scientists will be challenged to provide policy-relevant options; managers will be challenged to broaden their concerns and experiment openly; and policy makers will be challenged to act unselfishly on behalf of the broader community of people who value and depend on ocean ecosystems. As the committee addressed its charge—to review and evaluate the impacts of modern fisheries on the composition and productivity of marine ecosystems and their relevance to U.S. fisheries management, future research and stewardship of living marine resources—certain overarching principles and concepts emerged repeatedly. Taking a long-term and broad spatial view at multiple scales of resolution and extent is essential. Synthesis and food-web modeling provide alternative scenarios that can more robustly inform harvest strategies than can analyses of single populations. Social sciences and the tradeoffs between different fisheries and fishermen infuse all decisions on how best to harvest different components of food webs and to allocate these ocean resources among users. Sustaining ecosystem services from the ocean is equally as important as managing consumptive uses such as fisheries. Unfortunately, non-consumptive uses and ecosystem services are poorly accounted for and represented in fishery research, policy, and management. We have a vision of how to incorporate food-web considerations into fisheries management, but we do not have a practice or a handbook; iterative examination and response to changes in fish populations and communities will be the rule if we are to better steer marine ecosystems using fishery policies. The committee of nine included three fishery scientists, four aquatic ecologists, and two social scientists with broad knowledge of the issues. More specific information on the issues was presented by a broad group of scientists at the three
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Dynamic Changes in Marine Ecosystems: Fishing, Food Webs, and Future Options meetings of the committee. We greatly appreciated their contributions to our deliberations. I thank the committee members for their many contributions of text, ideas, and knowledge and their willingness to review, debate, and reach consensus. All members contributed and brought new information and insight to the process and valued judgment to the table. I thank and congratulate Dr. Christine Blackburn, our study director, who met the challenge of her first study committee at the National Research Council. I have been most pleased to work with her. I especially appreciate her dedication to the purpose of our task, her tireless effort to complete the report, her ability to learn, her demand for accuracy of the presented information, and her unselfish openness to debate and deliberation in order to reach consensus and synthesis. I thank Ms. Nancy Caputo, Research Associate, who has been a resourceful team member and whose imprint has greatly improved our report both broadly and in detail. I thank Mr. Phillip Long, Program Assistant, for facilitating our committee, our travels, and our teleconferences. These three are a good group. John J. Magnuson, Chair
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Dynamic Changes in Marine Ecosystems: Fishing, Food Webs, and Future Options Acknowledgments This report was greatly enhanced by the participants of the three workshops held as part of this study. The committee would first like to acknowledge the efforts of those who gave presentations at meetings: Villy Christensen, University of British Columbia; Jeremy Collie, University of Rhode Island; Joshua Eagle, University of South Carolina; Timothy Essington, University of Washington; David Fluharty, University of Washington; Michael Fogarty, Northeast Fisheries Science Center, National Oceanic and Atmospheric Administration; Anne Hollowed, Alaska Fisheries Science Center; James Kitchell, University of Wisconsin; Phillip Levin, National Oceanic and Atmospheric Administration; Steven Murawski, National Oceanic and Atmospheric Administration; Daniel Pauly, University of British Columbia; Alison Rieser, University of Maine; Michael Sissenwine, National Oceanic and Atmospheric Administration; and William Sydeman, Point Reyes Bird Observatory. These talks helped set the stage for fruitful discussions in the closed sessions that followed. This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the National Research Council’s Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making its published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We wish to thank the following individuals for their participation in their review of this report:
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Dynamic Changes in Marine Ecosystems: Fishing, Food Webs, and Future Options JEREMY S. COLLIE, University of Rhode Island, Narragansett SERGE GARCIA, U.N. Food and Agriculture Organisation (FAO), Rome, Italy RAY W. HILBORN, University of Washington, Seattle JEREMY B. JACKSON, University of California, San Diego, La Jolla MICHAEL K. ORBACH, Duke University, Beaufort, North Carolina PIETRO PARRAVANO, Commercial Fisherman, Half Moon Bay, California CLARENCE G. PAUTZKE, North Pacific Research Board, Anchorage, Alaska VICTOR RESTREPO, International Commission for the Conservation of Atlantic Tunas, Madrid, Spain CARL J. WALTERS, University of British Columbia, Vancouver, Canada JAMES WILSON, University of Maine, Orono Although the reviewers listed above have provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations nor did they see the final draft of the report before its release. The review of this report was overseen by John E. Burris, Beloit College, Beloit, Wisconsin, and May R. Berenbaum, University of Illinois, Urbana, who were appointed by the National Research Council, and who were responsible for making certain that an independent examination of this report was carried out in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this report rests entirely with the authoring committee and the institution.
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Dynamic Changes in Marine Ecosystems: Fishing, Food Webs, and Future Options Contents SUMMARY 1 1 INTRODUCTION 13 Policy Context, 15 Scientific Context, 17 Policy Choices and the Role of Science, 17 Moving Toward Ecosystem-Based Management, 19 Committee Approach and Report Organization, 20 2 EVIDENCE FOR ECOSYSTEM EFFECTS OF FISHING 23 Changes in Abundance and Biomass, 24 Genetic Changes in Populations, 32 The Phenomena of Shifting Baselines, 33 Altered Food Webs, 35 Trophic Cascades, 41 Fishing Down and Through the Food Web, 45 Responding to Regime Shifts, 51 Recovery, Stability, and Multiple Stable States, 53 Major Findings and Conclusions for Chapter 2, 56 3 CONSIDERING THE MANAGEMENT IMPLICATIONS 59 Fisheries Management Implications of Ecosystem Interactions, 60 Management Implications Aside from Trophic Interactions and Tradeoffs, 63
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Dynamic Changes in Marine Ecosystems: Fishing, Food Webs, and Future Options Developing Multiple Stock Harvest Strategies, 66 Mechanisms for Implementing Multi-Species Harvesting Strategies, 69 Overcoming Regulatory Constraints to Setting Multi-Species Reference Points, 74 Major Findings and Conclusions for Chapter 3, 75 4 INFORMING THE DEBATE: EXAMINING OPTIONS FOR MANAGEMENT AND STEWARDSHIP 77 Evaluating Strategic Management Options, 78 Projecting Recovery Strategies and the Effects of Shifting Baselines, 83 Strategies for Informed and Inclusive Decision Making, 84 Major Findings and Conclusions for Chapter 4, 90 5 SCIENCE TO ENABLE FUTURE MANAGEMENT 93 Improving Ecosystem Models and Scenario Analysis, 94 Analyzing Historical Time-Series Data, 99 Contributions from Social and Economic Science, 101 Major Findings and Conclusions for Chapter 5, 105 6 FINDINGS AND RECOMMENDATIONS 109 Recommendations, 110 REFERENCES 119 APPENDIXES A Committee and Staff Biographies 133 B List of Acronyms 139 C Committee Meeting Agendas 141 D Glossary 147