BIOLOGICAL REPORT 88(14) MAY 1988 SYNOPSIS OF THE BIOLOGICAL DATA ON THE LOGGERHEAD SEA TURTLE CARETTA CARETTA (LINNAEUS 1758) Fish and Wildlife Service U.S. Department of the Interior Biological Report This publication series of the Fish and Wildlife Service comprises reports on the results of research, developments in technology, and ecological surveys and inventories of effects of land-use changes on fishery and wildlife resources. They may include proceedings of workshops, technical conferences, or symposia; and interpretive bibliographies. They also include resource and wetland inventory maps. Copies of this publication may be obtained from the Publications Unit, U.S. Fish and Wildlife Service, Washington, DC 20240, or may be purchased from the National Technical Information Ser- vice (NTIS), 5285 Port Royal Road, Springfield, VA 22161. Library of Congress Cataloging-in-Publication Data Dodd, C. Kenneth. Synopsis of the biological data on the loggerhead sea turtle. (Biological report ; 88(14) (May 1988)) Supt. of Docs. no. : I 49.89/2:88(14) Bibliography: p. 1. Loggerhead turtle. I. U.S. Fish and Wildlife Service. 11. Title. 111. Series: Biological Report (Washington, D.C.) ; 88-14. QL666.C536D63 1988 597.92 88-600 12 1 This report may be cited as follows: Dodd, C. Kenneth, Jr. 1988. Synopsis of the biological data on the Loggerhead Sea Turtle Caretta caretta (Linnaeus 1758). U.S. Fish Wildl. Serv., Biol. Rep. 88(14). 110 pp. Biological Report 88(14) May 1988 Synopsis of the Biological Data on the Loggerhead Sea Turtle Caretta caretta (Linnaeus 1758) C. Kenneth Dodd, Jr. U.S. Fish and Wildlife Service National Ecology Research Center 412 N.E. 16th Avenue, Room 250 Gainesville, FL 32601 FA0 Synopsis NMFS-149 Fish and Wildlife Service U.S. Department of the Interior Washington, DC 20240 Preparation of this Synopsis This review is the first to collate and synthesize the history, the many unknowns concerning its biology and published data on the biology and management require- habitat requirements, and the global threats to the ments of the loggerhead sea turtle. It is likely that much oceanic ecosystem illustrate the complexity in for- additional information may be found in little known or mulating effective management strategies. difficult to obtain unpublished reports or governmental documents. With the publication of this synopsis, it is I thank the many individuals who assisted me in hoped that those working on loggerhead projects will bringing together these literature sources, particularly be stimulated to publish their information and thus Kay Lindgren and Bert Charest of the National Ecology make it available to biologists and resource managers Research Center. I especially thank the following who who need it to plan for the conservation of this threat- generously donated reprints, translated articles, or ened species. General reviews of loggerhead biology reviewed the manuscript: Mehmet K. Atatur, George have been provided by Carr (1952), Ernst and Barbour Balazs, Karen Bjorndal, Richard Byles, Heike Charest, (1972), Hendry et al. (1982), and Nelson (1986). This Nat Frazer, Carol Hahn, Terry Henwood, Kazuo review follows the FA0 synopsis format prepared by Horikoshi, George Hughes, Anne Meylan, Jeffrey Rosa (1965). The purpose of the FA0 synopses is to Miller, Larry Ogren, David Owens, Peter Pritchard, make available existing data to biologists and, by doing J. Perran Ross, Hobart S. Smith, Rosalie Vaught, so, to draw attention to gaps in our knowledge and thus Myrna Watanabe, Jeanette Wyneken, and George Zug. stimulate research in areas needing study. Susan Strawn and Bert Charest prepared the figures. Preparation of this synopsis was supported by a grant Governments and conservation organizations from the Endangered Species Office, U.S. Fish and throughout the world have designated the loggerhead Wildlife Service, Albuquerque, New Mexico. I thank and other species of sea turtles as vulnerable or threaten- Jack Woody for arranging this support. This synopsis ed species in need of management in order to ensure is dedicated to the memory of the late Archie F. continued survival and evolutionary potential. The Carr, Jr., who inspired me, as he inspired others, with widespread distribution of the species, its elusive life his love of and concern for these giant reptiles. Ill Abstract This synopsis compiles and reviews the available of the loggerhead sea turtle, Caretta caretta (Linnaeus information on the identity, distribution, life history, 1758), a species threatened by exploitation and the populations, exploitation, protection, and management alteration and destruction of its habitat. Contents page . ... Preparation of this Report .................................................................. in Abstract.................................................................................. v 1. IDENTITY ........................................................................... 1 1.1 Nomencl ature................................................................... 1 1. 1. 1 Valid name .............................................................. 1 1.1.2 Synonymy ............................................................... 1 1.2 Taxonomy ...................................................................... 2 .- . 1.2.1 Allinities ................................................................. 2 1.2.2 Taxonomic status ......................................................... 3 1.2.3 Subspecies ............................................................... 3 1.2.4 Standard common names .................................................. 4 1.2.5 Definition of size categories ................................................. 4 1.3 Morphology .................................................................... 5 1.3.1 Externallinternal morphology and coloration .................................. 5 1.3.2 Cytomorphology ..........................................................13 1.3.3 Protein composition and specificity .......................................... 14 2 . DISTRIBUTION ......................................................................16 2.1 Total Area .....................................................................16 2.2 Differential Distribution .......................................................... 26 2.2.1 Hatchlings ...............................................................26 2.2.2 Juveniles, subadults, and adults ............................................. 27 2.3 Determinants of Distributional Changes ............................................ 27 ... 2.4 Hybridization ...................................................................28 3 . BIONOMICS AND LIFE HISTORY .................................................... 28 3.1 Reproduction ................................................................... 28 3.1.1 Sexuality ................................................................. 28 3.1.2 Maturity .................................................................29 3.1.3 Mating .................................................................. 29 ... 3.1.4 Fertilization ..............................................................31 3.1.5 Gonads ..................................................................31 3.1.6 Nesting Process ........................................................... 32 3.1.7 Eggs .................................................................... 38 3.2 Embryonic and Hatchling Phase ................................................... 43 3.2.1 Embryonic phase .......................................................... 43 3.2.2 Hatchling phase .......................................................... 47 3.3 Juvenile, Subadult, and Adult Phase ...............................................52 3.3.1 Longevity ................................................................ 52 3.3.2 Hardiness ................................................................ 53 3.3.3 Competitors .............................................................. 54 3.3.4 Predators ................................................................ 54 3.3.5 Parasites and commensals .................................................. 54 3.4 Nutrition and Growth ............................................................ 60 3.4.1 Feeding .................................................................. 60 3.4.2 Food .................................................................... 61 3.4.3 Growth rate .............................................................. 66 3.4.4 Metabolism .............................................................. 69 3.5 Behavior ....................................................................... 69 3.5.1 Migrations and local movements ............................................ 69 3.5.2 Schooling ................................................................ 71 . 3.5.3 Responses to stimuli ....................................................... 71 VII 4 . POPUL. ATION 4.1 Structure ....................................................................... 4.1.1 Sex ratio ................................................................. 4.1.2 Age composition .......................................................... 4.1.3 Size compos~tion.......................................................... 4.2 Abundance and Density .......................................................... 4.2.1 Average abundance and density ............................................. 4.2.2 Changes in abundance and density .........................................