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DECLINE OF THE SEA TURTLES
DECLINE 0' THE SEA TURTLES CAUSES AND PREVENTION Committee on Sea Turtle Conservation Board on Environmental Studies anc! Toxicology Boarcl on Biology Commission on Life Sciences National Research Council NATIONAL ACADEMY PRESS Washington, D.C. 1990
NATIONAL ACADEMY PRESS 2101 Constitution Avenue, N.W. Washington, D.C. 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 report has been reviewed by a group other than the authors according to proce- dures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The project was supported by the Department of Commerce under contract number 50 DGNC 9 00080. Cover: Loggerhead turtle. Photograph courtesy of the Florida Audubon Society. Frontispiece: Thousands of fish and a loggerhead turtle caught in a shrimp trawl. The turtle is alive and apparently uninjured. The fish are dead. Photograph: Michael Weber, Center for Marine Conservation. Photographs on chapter-opening pages are courtesy of Peter Pritchard and the Florida Audubon Society, and Michael Weber, Center for Marine Conservation. Library of Congress Cataloging-in-Publication Data Decline of the sea turtles: causes and prevention / Committee on Sea Turtle Conservation, Board on Environ- mental Studies and Toxicology, Board on Biology, Com- mission on Life Sciences, National Research Council. p. cm. Includes bibliographical references and index. ISBN 0-309-04247-X: $14.95 1. Sea turtles. 2. Endangered species. 3. Wildlife conservation I. National Research Council (U.S.). Committee on Sea Turtle Conservation. QL666.C536D43 1990 639.9'7792--dc20 Copyright ~1990 by the National Academy of Sciences 90-38318 CIP No part of this book may be reproduced by any mechanical, photographic, or electronic process, or in the form of a phonographic recording, nor may it be stored in a retrieval sys- tem, transmitted, or otherwise copied for public or private use, without written permission from the publisher, except for the purposes of official use by the U.S. government. Printed in the United States of America
Decline of the Sea Turtles CommiNee on Sea Turde Conservation ,lohn,,. Magnuson, Chair, University of Wisconsin, Madison Karen A. Bjorndal, University of Florida, Gainesville William D. DuPaul, Virginia Institute of Marine Science, College of William and Mary, Gloucester Point Gary L. Graham, Texas A&M University, College Station David W. Ovens, Texas A&M University, College Station Charles H. Peterson, University of North Carolina, Morehead City Peter C. H. Pritchard, Florida Audubon Society, Maitland James I. Richardson, University of Georgia, Athens Gary E. Saul, FTN Associates, Austin, Texas Charles W. West, Nor'Eastern Trawl Systems, Bainbridge Island, Washington Project Staff David,,. Policansky, Program Director Dave,iohnston, Project Director Norman Grossblatt, Editor Bernidean Williams, Information Specialist Linda B. Kegley, Project Assistant
iv Decline of the Sea Turtles Board on Environmental ShJdies and Toxicology Gilbert S. Omenn, Chair, University of Washington, Seattle Frederick R. Anderson, Washington School of Law, American University, Washington, D.C. John Bailar, McGill University School of Medicine, Montreal, Quebec Lawrence W. Barnthouse, Oak Ridge National Laboratory, Oak Ridge, Tennessee David Bates, University of British Columbia, Vancouver Joanna Burger, Rutgers University, Piscataway, New Jersey Yoram Cohen, University of California, Los Angeles John L. Emmerson, Eli Lilly & Company, Greenfield, Indiana Robert L. Harness, Monsanto Agricultural Company, St. Louis, Missouri Paul,}. Lloy, UMDNI-Robert Wood Johnson Medical School, Piscataway, New Jersey bane Lubehenco, Oregon State University, Corvallis Donald Mattison, University of Arkansas for Medical Sciences, Little Rock Duncan T. Patten, Arizona State University, Tempe Nathaniel Reed, Hobe Sound, Florida William H. Rodgers, University of Washington, Seattle F. Sherwood Rowland, University of California, Irvine Liane B. Russell, Oak Ridge National Laboratory, Oak Ridge, Tennessee Milton Russell, University of Tennessee, Knoxville John H. Seinfeld, California Institute of Technology, Pasadena I. Glenn Sipes, University of Arizona, Tucson Bruce M. Alberts bex officioJ, University of California, San Francisco Donald Hornig Sex officio", Harvard School of Public Health, Boston, Massachusetts Paul Risser (ex officio", University of New Mexico, Albuquerque Staff ,iames,,. Reisa, Director David,}. Policansky, Applied Ecology and Natural Resources Program Director Robert Smudge, Exposure Assessment and Risk Reduction Program Director Richard D. Thomas, Human Toxicology and Risk Assessment Program Director Lee R. Paulson, Manager, Toxicology Information Center
v Decline of the Sea Turtles Board on Biology Francisco,'. Ayala, Chair, University of California, Irvine Nina V. Fedoroff, Carnegie Institution of Washington, Baltimore Maryland Timothy H. Goldsmith, Yale University, New Haven, Connecticut Ralph W. F. Hardy, Boyce Thompson Institute for Plant Research, Ithaca, New York Ernest G.,laworski, Monsanto Company, St. Louis, Missouri Harold A. Mooney, Stanford University, Stanford, California Harold,,. Morowitz, George Mason University, Fairfax, Virginia Mary Lou Pardue, Massachusetts Institute of Technology, Cambridge David D. Sabatini, New York University, New York Michael E. Soule, University of Michigan, Ann Arbor Malcolm S. Steinberg, Princeton University, Princeton, New Jersey David B. Wake, University of California, Berkeley Bruce M. Alberts (ex officio", University of California, San Francisco Oskar R. Zaborsky, Director
vi Decline of the Sea Turtles Commission on Life Sciences Bruce M. Alberts, Chair, University of California, San Francisco Bruce N. Ames, University of California, Berkeley Francisco,}. Ayala, University of California, Irvine ,'. Michael Bishop, University of California Medical Center, San Francisco Freeman,'. Dyson, Institute for Advanced Study, Princeton, New lersey Nina V. Fedoroff, Carnegie Institution of Washington, Baltimore, Maryland Ralph W. F. Hardy, Boyce Thompson Institute for Plant Research (Cornell University), Ithaca, New York Leroy E. Hood, California Institute of Technology, Pasadena Donald F. Hornig, Harvard School of Public Health, Boston, Massachusetts Ernest G.,iaworski, Monsanto Company, St. Louis, Missouri Marian E. Koshland, University of California, Berkeley Harold A. Mooney, Stanford University, Stanford, California Steven P. Pakes, University of Texas, Dallas Joseph E. Rall, National Institutes of Health, Bethesda, Maryland Richard D. Remington, University of Iowa, Iowa City Paul G. Risser, University of New Mexico, Albuquerque Richard B. Sallow, Brookhaven National Laboratory, Upton, New York, New York Torsten N. Wiesel, Rockefeller University, New York, New York John E. Burris, Executive Director
Preface The Committee on Sea Turtle Conservation was formed on March 1, 1989, under the auspices of the Board on Environmental Studies and Tox- icology (BEST) and the Board on Biology of the National Research Coun- cil's Commission on Life Sciences. The committee was formally charged as follows: The task of this committee is to perform a study mandated by the Endangered Species Act Amendments of 1988, reviewing scientific and technical information pertaining to the conserva- tion of sea turtles and the causes and significance of turtle mortality, including that caused by commercial trawling. The committee's report will provide information on the population biology, ecology, and behavior of five endangered or threat- ened species: the Kemp's ridley, loggerhead, leatherback, hawksbill, and green sea turtles. The committee will also review information on the effectiveness of current and needed programs to increase turtle populations. The resulting report will be used by the Secretary of Commerce to assess the effec- tiveness of and need for regulations requiring the use of turtle- excluder devices (TEDs) by commercial shrimp-trawlers. . . v''
vial Decline of the Sea Turtles In addition to this final report, the committee was required to prepare an interim report on the status of the Kemp's ridley (see Section 1008 of the Endangered Species Act Amendments of 1988 in Appendix A). The interim report on Kemp's ridley is enclosed as Appendix B. The committee met on May 4-5, June 26-29, September 28-30, and November 16-18, 1989. In addition, a writing group met in Washington, D.C., on December 4-5, 1989. The committee was fortunate to have as members experts on turtle biology, physiology, and conservation, shrimp fishing and gear technolo- gy (in particular, trawl and TED technology), fishery biology and manage- ment, and technology transfer and fishery extension programs. All these kinds of expertise were required to address the complex issues of sea tur- tle conservation. I was especially pleased by the new analyses and syn- theses that the committee was able to make that allowed us to reach a number of important conclusions with more certainty than I originally had expected. To gain further knowledge of TEDs and other gear operations, the committee sailed for a day off the coast of Jekyll Island, Georgia, on the RV/Georgia Bulldog. The trip was made possible through the courtesy of David Harrington. We were assisted greatly by the National Research Council staff, in par- ticular, Dave Johnston, our project director, and Linda Kegley, our project assistant. We also acknowledge the guidance of David Policansky, pro- gram director; James ]. Reisa, director of BEST; and Joanna Burger, our BEST liaison. In addition to those persons, other BEST staff jumped in to help when needed. Bernidean Williams, information specialist, helped to check references. Norman Grossblatt of the Commission on Life Sciences and Lee ' Paulson of BEST edited the report. My personal thanks to them all. We also thank a number of persons who either prepared presentations for the committee or made original data available to the committee for analysis and interpretation. 'Those who provided testimony were Michael Weber (Center for Marine Conservation), Larry Ogren (National Marine Fisheries Service), Earl Possardt (U.S. Fish and Wildlife Service), Charles Oravetz (National Marine Fisheries Service), Tee John Mialjevich (Con- cerned Shrimpers of America), Carol Ruckdeschel (Cumberland Museum), David Harrington (University of Georgia Marine Extension Service), Joe Webster (Commercial Shrimp Fisherman), David Blouin (Department of Experimental Statistics, Louisiana State University), Elizabeth Gardner (leg- islative assistant to Senator Howell Heflin), and David Cottingham (National Marine Fisheries Service). Those who provided data include Wendy Teas, Nancy Thompson, Terry Henwood, Warren Stuntz, Edward F. Klima, Ren Lohoefener, Ernie Snell, James Nance, and Guy Davenport,
ix Decline of the Sea Turtles all with the National Marine Fisheries Service; Alan Bolten (University of Florida); Michael Harris (Georgia Department of Natural Resources); Tom Henson (North Carolina Nongame Endangered Wildlife Program); and Sally Murphy (South Carolina Wildlife and Marine Resources). Without their assistance we would not have been able to make our report current. I wish to thank my own colleagues in the Center for Limnology at the University of Wisconsin-Madison, who assisted with analyses and data transfer: Chris Carr, Barbara I. Benson, Inga Larson, Norma D. Magnuson, Mark D. McKenzie, Mary Rose Lawocki Smith, and Joyce M. Tynan. Assis- tance to other committee members was provided by Nancy Balcom (Vir- ginia Institute of Marine Science), David Rostal (Texas A&M University), and Hal Summerson and Alberto Reyes-Campo (University of North Car- olina, Institute of Marine Sciences). We dedicate this volume to the peaceful coexistence of sea turtles and shrimp fisheries. John J. Magnuson Chairman April 23, 1990
x Decline of the Sea Turtles The National Academy of Sciences is a private, nonprofit, self-perpetu- ating society of distinguished scholars engaged in scientific and engineer- ing 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. Frank Press is president of the National Academy of Sci ences. 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 Sci- ences the responsibility for advising the federal government. The Nation- al Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recog- nizes the superior achievements of engineers. Dr. Robert M. White 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. Samuel O. Thier is president of the Institute of Medicine. The National Research Council was organized by the National Acade- my 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 princi- pal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the govern- ment, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Frank Press and Dr. Robert M. White are chairman and vice chairman, respectively, of the National Research Council.
Contents EXECUTIVE SUMMARY 1 INTRODUCTION 2 BIOLOGY................. Kemp's Ridley, 23 Loggerhead, 28 Green Turtle, 32 Hawksbill, 35 Leatherback, 39 Olive Ridley, 41 3 POPULATION TRENDS Kemp's Ridley, 43 Loggerhead, 47 Green Turtle, 48 Hawksbill, 48 Leatherback, 49 Summary, 49 .16 X! .42
xii Decline of the Sea Turtles 4 DISTRIBUTION OF SEA TURTLES IN U.S. WATERS 51 Sources of Information, 51 Distribution, 54 Onshore, Offshore, and Depth Distribution, 58 Summary, 60 5 NATURAL MORTALITY AND CRITICAL LIFE STAGES . Biotic Sources of Mortality, 62 Abiotic Sources of Mortality, 66 Quantitative Studies of Natural Mortality, 67 Summary, 72 ....... 61 6 SEA TURTLE MORTALLY ASSOCIATED WITH HUMAN AClIVlT~S 74 Mortality of Sea Turtle Eggs and Hatchlings, 77 Mortality of Sea Turtle Juveniles and Adults, 82 Summary, 116 7 CONSERVATION MEASURES Rationale and Objective of the Recovery Plan, 119 Description of Conservation Measures, 120 Reducing Adult and Subadult Mortality Associated with Human Activities, 125 Education and Technology Transfer, 140 Conservation Efforts in Other Jurisdictions, 142 8 CONCLUSIONS AND RECOMMENDATIONS Conclusions, 144 Recommendations, 146 REFERENCES APPENDIXES .118 144 154 A. ENDANGERED SPECIES ACT AMENDMENTS OF 1988 175 B. INTERIM REPORT, COMMIT1't;E ON SEA TURTLE CONSERVATION 179
xiii Decline of the Sea Turtles C. ILLUSTRATIONS OF TURTLE EXCLUDER DEVICES 193 D. AERIAL SURVEY DATA OF SEA TURTLES IN FISHING ZONES.................................................................. .199 E. SEA TURTLE STRANDING DATA 202 F. SHRIMP FISHING EFFORT G. ANNOTATED AND CHRONOLOGICAL LIST OF EDUCATIONAL EFFORTS ON TEDs FOR FISHERMEN BY NATIONAL MARINE FISHERIES SERVICE 218 .215 H. ANNOTATED AND CHRONOLOGICAL LIST OF EDUCATIONAL EFFORTS ON TEDs FOR FISHERMEN BY SEA GRANT 224 I. NEWSLE'l~l'~RS AND NOTICES PERTAINING TO TEDs 238 J. BIOGRAPHIES OF COMMI'l~l'~E MEMBERS........................................................... .249 INDEX 253