Dynamic Changes IN MARINE ECOSYSTEMS
Fishing, Food Webs, and Future Options
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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.
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Cover art by Ray Troll, “North Pacific Marine Life,” © 1986
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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
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.
The committee and staff biographies are provided in Appendix A.
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
University of Hawaii at Manoa
ROBERT G. BEA,
University of California, Berkeley
Texas A&M University, College Station
MARY (MISSY) H. FEELEY,
ExxonMobil Exploration Company, Houston, Texas
Tampa Bay National Estuary Program, St. Petersburg, Florida
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
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
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
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
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
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
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
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:
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.