BIOLOGICAL REPORT 97(1) AUGUST 1997 Synopsis of the Biological Data on the Green Turtle Harold F. Hirth Department of Biology University of Utah Salt Lake City, Utah 841 12 USA Fish and Wildlife Service U. S. Department of the Interior Washington, D. C. 20240 Preparation of this Synopsis This review of the green turtle, Chelonia mydas. has mitt= aided travel to libraries. Ms. Jeanette Stubbe gra- been prepared following the FA0 fisheries synopsis out- ciously and conscientiously typed several versions of the line of Rosa (1965) and as applied to marine turtles by manuscript. Mr. Keny Matz prepared the figures. Dr. ffirth (197Ib). John Roth; Chairman of the Biology Department, sup- The main purposes of this synopsis am to bring together parted the author with. some sabbatical leave time. the current and salient information on the biology of the Itis a pleasure to acknowledge Dr. David W. Ehrenfeld, green turtle and to draw attention to some of the major Dr. Nicholas Mrosovsky, Dr. Mark Nielsen and Dr. Peter gaps in our knowledge of the species. Because of the C. H. Pritchaid for their helpful comments after review- nature of a synopsis, i.e., that of providing an entry into ing an earlier version of the manuscript the literature, researchers should peruse die original pa- The author'thanks Drs. Leslie Dieraof and Richard pers for details of methodologies and conclusions. Byles, Ms. Susan MacMullin and Mr. Art Needleanan of The author is indebted to Ms. Linda Bums, Imerlibrary the Endangered Species Office,U. S. Fish and Wildlife Loan Supervisor, University of Utah, for helpful and Service, Albuquerque, New Mexico for help and for sup timely assistance in obtaining some rare publications. porting the publication of this synopsis. Assistance from the University of Utah Research Corn- I ii --- Abstract This document reviews the salient and current litera- studies on a few nesting beaches have disclosed signifi- ture on the biology of the green turtle, Chelonia my& cant annual fluctuations in numbers of nesters. Under (Linnaeus, 1758) including taxonmy, distribution,phy &- natural conditions there is high predation on eggs and ~logy,morphology, ecology, demography, exploitation hatchlings and low predarion on adults. Long life was and conservation. Fifteen figures and 17 tables supple- probably the norm for those that survived neonatal mor- ment the text. tality. before the advent of humans. A green turtle survi- In general, green turtles arelaige sea turtles well adapted vorship curve is roughly concave, under natural condi- to marine life. They are cireumglobal, conanonly occur- tions. Green turtles are host to a large variety of para- ring in warm, tropical seas. They occur in offshore wa- sites, and fibropapillomatosis is a significant disease in ters or on the nesting beaches of at least 139 countries ~inewidely scattered areas. Major food competitors on and terriiories. Most nesting sites are located between the seagrass pastures are dugongs, fishes and sea urchins. 30ÂN and 30 S latitudes. The green turtle is a morpho- As expected, studies have shown how many aspects of species, made-up of several distinct populations and the turtles' physiology are related to their feeding habits, meiapopulations. The total range of a population~en- reproductive cycles, prolonged swimming, diving and compassing the nesting beach, epipelagic habitat, feed- migrations. References are provided on morphological ing grounds and migrations~canbe very extensive. descriptions of the embryo, egg shell, skull, lung, kidney. Sex is determined by substrate temperatures during in- ovary and oviduct. cubation with wanner temperatures producing females, Some major gaps in our knowledge of green turtles are The diploid chroniosome number is 56 and there are no speciation rates, natural sex ratios, ecologies of hatchlings heteromorphic sex chromosomes. Hatchlings use visual and juveniles during the "lost years", biology of males, cues in crawling to the sea and then, in shallow water, survival rates of different size classes, and navigation they orient by swimming into the waves. Magnetic cues mechanisms. Obtaining information on some of these may be used for orientation in deep water. The cues used parameters can be aided by the development of reliable by navigating adult turtles in their long-distance gametic marking and tracking systems. migrations are unknown. Satellite telemetry may prove Because of many decades of overexploitation by hu- useful in this regard. Recent mWNA research supports-a roans, most green turtle populations are endangered or natal homing hypothesis. Hatchlings and small juveniles threatened today. Degradation of nesting beaches and are chiefly carnivorous (or omnivorous) while subadults oceanic pollution are additional threats to green turtle and adults are chiefly herbivorous. Trophic level changes survival almost everywhere now. Conservation of any are associated with ontogenetic habitat shifts. one population will almost certainly involve regional co* Much more is known about females than males because operation. All populations are important because they the former are easily studied on the nesting beaches. Green are the evolving units in nature and because they repre- turtles are characterized by slow growth, delayed sexual sent genetic diversity. For conservation purposes, each maturity, high fecundity, iteroparity, and a relatively long green turtle nesting population should be viewed as an reproductive life (under natural conditions). Reproduc- autonomous demographic entity. Preservation of the tive data, from many nesting sites, are provided in tabular turtles' critical habitats, education, and enforcement of form: sizes ofnesters, clutch sizes and number of clutches existing protective regulations are among (he management per season, egg and hatchling dimensions, remigration strategies discussed. intervals and hatching success. Long-range demographic ill Contents Preparation of &is Synopsis ........................................................................................................................................ ...ii Abstract ............................................................ ........,.................................................*.,............. ..................... ............ 111 1.1 Nomenclature .......................; .............................*..................................‘............................................... 1 1.1.1 Valid name ................................................................................................................................... 1 1.1.2 Synonymy ............................................ã...............................................................ã.................. 1 1.2 Taxonomy ................................................................................................................................................ 2 1.2.1 Afiimties ....................................................................; ................................................................. 2 1.2.2 Taxonomic status .................................................... .............................................................*....2 1.2.3 Subspecies .....-............................................................................................................................ 2 1.2.4 Standard common names ......-....................................................................................................5 1.2.5 Definition of size categories ................; ....................................................................................... 6 1.3 Morphology ...........................................................................; ................................................................. 6 1.3.1 External/internal morphology and coloration ............................................................................ 6 1.3.2 Cytomorphology ...............: ....................................................................................................... 11 1.3.3 Protein composition and specificity and general physiology .................................................... 12 DIS.TMBTJTION ................................................................................................................................................ 13 2.1 TotalArea .............................................................................................. ...................................... .... ....... 13 2.2 Differential Distribution ..........................................................................................................................14 2.2.1 Hatchlings ................................................................................................................................. 14 2.2.2 Juveniles. subadults. and adults ................................................................................................ 14 23 Determinants of Distributional Changes ................................................................................................25 2.4 Hybridization ................. :........ :..........................................,................................................................... 25 BIONOMICS AND LIFE HISTORY .................................................................................................................25 Reproduction ..........................................................................................................................................