FAO Fisheries Synopsis No. 137 FIR/S137 (Distribution restrictei) SAST - Hawlcsbill turtle 5,31(07)017,01 bk)PSIS OF BIOLOGICAL DA N THE HAWKS LL TURTL Eretmoch1ys 1mb icata (Liae 17) PrepaLed ry W.N. Witzell F O FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS FISHERIES SYNOPSES This series of documents, issued by FAO, CSIRO, INP and NMFS, contains comprehensive reviews of present knowledge on species and stocks of aquatic organisms of present or potential economic interest. The Fishery Resources and Environment Division of FAO is responsible for the overall coordination of the series. The primary purpose of this series is to make existing information readily available to fishery scientists according to a standard pattern, and by so doing also to draw attention to gaps in knowledge. It is hoped that synopses in this series will be useful to other scientists initiating investigations of the species concerned or of related ones, as a means of exchange of knowledge among those already working on the species, and as the basis for comparative study of fisheries resources. They will be brought up to date from time to time as further information becomes available. The documents of this Series are issued under the following titles: Symbol FAO Fisheries Synopsis No. FIR/S SI RO Fisheries Synopsis No. D FO/S I NP Sinopsis sobre la Pesca N° IN P/S NM FS Fisheries Synopsis No. NMFSIS Synopses in the series are compiled according to a standard outline described in Fib/Si Rev. 1(1965). FAO, CSIRO, INP and NMFS are working to secure the cooperation of other organizations and of individual scientists in drafting synopses on species about which they have knowledge, and welcome offers of help in this task. Additions and corrections to synopses already issued will also be most welcome. Comments on individual synopses and requests for information should be addressed to the coordinators and editors of the issuing organizations, and suggestions regarding the expansion or modification of the outline to FAO: FAO: CSIRO: Fishery Resources and Environment Division CSIRO Division of Fisheries and Oceanography Marine Resources Service Box 21 Food and Agriculture Organization of the United Nations Cronulla, N.S.W. 2230 Via delle Terme di Caracalla Australia 00100 Rome, Italy INP: NM FS Instituto Nacional de Pesca Scientific Publications Office Subsecretaria de Pesca National Marine Fisheries Service, NOAA Secretaría de Pesca 1107 N.E. 45th Street Secretaría de Industria y Comercio Seattle, WA. 98105, USA Carmona y Valle 101-403 México 7, D.F. Consolidated lists of species or groups covered by synopses issued to date or in preparation will be issued from time to time. Requests for copies of synopses should be addressed to the issuing organization. The following synopses in this series have been issued since January 1981: FIRIS128 Synopsis of biological data on the western rock lobster, Panu/irus cygnus George, 1962 - B.F. PHILLIPS, G,R. MORGAN and C.M. AUSTIN 1980 NMFSIS124 Synopsis of biological data on frigate tuna, Aux is thazard, and bullet tuna, A. rochei - R.N. UCHIDA 1981 NM FS/S1 27 Synopsis of biological data on the swordfish, Xiphias gladius Linnaeus - B.J. PALKO, G.L. BEARDSLEY and W.J. RICHARDS 1981 NMFSIS13O Synopsis of biological data on dolphinfishes, Coryphaena hippurus Linnaeus and Coryphaena equise/is Linnaeus - J.B. POLKS, G.L. BEARDSLEY, and W.J. RICHARDS 1982 FI R/Si 31 Exposé synoptique des données biologiques sur Heterotis nioticus (Cuvier, 1829) J. MOREAU 1982 FIR/S132 Exposé synoptique des données biologiques sur Lates nioticus (Linnaeus, 1762) J. MOREAU 1982 FIR/8129 Exposé synoptique des données biologiques sur les mérous, Epinephe/us aeneus and E. guaza de l'océan Atlantique et de la Méditerranée - J. BRUSLE inpreparation NMFS/S133 Synopsis of biological data on grunts, Haemu/on auro/ineatum and H. plum/en - G.H. DARCY in press NM FSIS1 34 Synopsis on biological data of the pigfish, Orthopristis chrysoptera - G.H. DARCY in press FI R/S135 Synopsis ofbiologicaldata on the grass carp Ctenopharyngodon ide/Ia (Cuvier and Valenciennes, 7844) - J.V. SHIREMAN and C.R. SMITH in press NMFS/S136 Synopsis on biological data on skipjack tuna, Katsuwonus po/amis (Linnaeus, 1758) - W.M. MATSUMOTO, R.A. SKILLMAN and A.E. DIZON in press FAO Fisheries Synopsis No. 137 FIR/S137 (Distribution restricted) SAST - Hawksbill turtle - 5,31 (07) 017,01 SYNOPSIS OF BIOLOGICAL DATA ON THE HAWKSBILL TURTLE Eretmochelys imbricata (Linnaeus, 1766) Prepared by W.N. Witzell US Department of Commerce National Oceanic and Atmospheric Administration National Marine Fisheries Service Southeast Fisheries Center 75 Virginia Beach Drive Miami, Florida 33149 USA FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Rome 1983 11 FIR/Sl37 Hawksbill turtle PEEPAR.ATION OF THIS SYNOPSIS This review is the first attempt to collate and synopsize the existing fragments of hawksbill data which are scattered throughout a myriad of published and unpublished reports. In order to address all pertinent categories of data, this review follows the FAO species synopsis format pre- pared by Rosa, Jr (1965). The hawksbill sea turtle has been harvested for centuries for its meat and its beautiful mottled carapace scutes, called "tortoise shell". However, hawksbills appear to be dwindling rapidly over much of their range due to overexploitation and habitat destruction. The world-wide scientific and conservation community has therefore declared the hawksbill an endangered species, The basic biology and population dynamics of the hawksbill turtle, needed by resource managers, is poorly understood. The hawksbill is an elusive animal, diffusely nesting over extended nesting seasons on scattered tropical beaches throughout its range. They may be ubiquitous in shallow waters surrounding tropical reefs but are not often seen, and the females are generally very rapid nesters, making them difficult to study. They are opportunistic omnivores with little apparent tendency to migrate great distances en masse, Also, the hawksbill turtle, unlike many marine vertebrates, apparently consists of many separate populations that mate and nest independently at site specific locations. These factors combined illustrate the complexity of formulating rational management strategies. ABSTRACT This synopsis compiles and reviews the scattered information on the identity, distribution, life history, populations, exploitation, protection, management and mariculture potential of the hawksbill turtle, Eretmochelys imbricata (Linnaeus, 1766), harvested for centuries for its meat and carapace scutes, Distribution For bibliographic purposes this document should be cited as follows: Author FAO Fisheries Department Witzell, W,N., Synopsis of biological FAO Regional Fisheries Officers 1983 data on the hawksbill turtle, Regional Fisheries Councils and Eretmochelys imbricata Commissions (Linnaeus, 1766). FAO Fish. Selector SM Synop., (l37):78 p. The designations employed and the presentation of material in thia publication do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization oftheUnitedNationsconcerningthelegal statua of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. M-42 ISBN 92-.5.'..101356X Allrights reserved. No part of thispublicationmay be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic,mechanical, photocopying or otherwise, without theprior permission of the copyright owner.Applications for such permission, with a statement of the purpose and extent of the reproduction, should be addressed to the Director, Publications Division, Food and Agriculture Organization of the United Nations, Vis delle Terme di Caracalla, 00100 Rome, Italy. © FAO 1983 FIR/S137 Hawksbill turtle CONTENTS Page IDENTITY 1 1.1 Nomenclati.ire i 1.1.1 Valid name 1 1.1.2 Synonymy 1 1.2 Taxonomy i 1.2.1 Affinities i 1.2.2 Taxonomie status I 1.2.3 Subspecies i 1.2.4 Standard common names 3 1.2.5 Definition of size categories 3 1.3 Morphology 3 1.3.1 External/internal morphology and colouration 3 1.3.2 Cytomorphology - 7 1.3,3 Protein composition and specificity 8 DISTRIBUTION 8 2.1 Total Area 8 2.2 Differential Distribution 16 2.2.1Hatchiings 16 2.2.2 Juveniles, subadults and adults 16 2.3 Determinants of Distributional Changes 16 2.4 Hybridization 16 3. BIONONICS AND LIFE HISTORY 16 3.1 Reproduction 16 3.1.1Sexuality 16 3.1.2Maturity 16 3,1.3 Mating 17 3.1.4Fertilization 18 3.1.5 Gonads'2/ 3,1.6Nesting process 18 3.1.7 Eggs 21 3.2Embryonic and Hatching Phase 25 3.2.1Embryonic phase 25 3.2.2Hatchling phase 26 3.3 Juvenile, Subadult and Adult Phase 28 3.3.1Longevity 28 3.3.2 Hardiness 28 3.3.3 Competitors 30 3,3.4Predators 30 3.3,5 Parasites and commensals 30 3.4 Nutrition and Growth 35 3,4.1 Feeding 35 3.4.2 Food 35 3.4.3 Growth rate 35 3.4.4 Metabolism iv FIR/S137 Hawksbill turtle Page 3,5 Behaviour 43 3.5.1 Migrations and local movements 43 3.5,2 Schooling 43 3.5.3 Responses to stimuli 43 4. POPULATION 44 4.1 Structure 44 4.1,1 Sex ratioLl' 4,1.2Age composition 44 4,1.3 Size composition 44. 4.2 Abundance and Density 44 4.2.1 Average abundance and density 44 4.2.2 Changes in abundance and density 45 4.3 Natality and Recruitment 45 4,3.1 Reproduction rates .45 4.3.2 Factors affecting reproduction 45 4.3.3 Recruitment' 4.4 Mortality 45 4.4,1Mortality ratesL/ 4,4.2Factors causing or affecting mortality 45 4.5 Dynamics of Population 46 4,6 The Population in the Community and the Ecosystem 46 5, EXPLOITATION 46 5.1 Fishing Equipment and Methods 46 5.2 Fishing Areas 48 5.3 Fishing Seasons 48 5.4 Fishing Operations and Results 48 PROTECTION AND MANAGEMENT 50 6.1 Regulatory Measures 50 6.2 Management Strategies 51 6,3 Artificial Stocking 51 MARICIJLTURE 52 REFERENCES 53 1/ No information available FIR/S137 Hawksbill turtle 1 1.