NOAA Technical M m andum NMFS SYNOPSIS OF BIOLOGICAL DATA ON THE GREEN TURTLE IN THE HAWAIIAN ISLANDS George H. Balazs fi m NOM-TNHVMFS-S WFC-7 October 1980 U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Marine Fisheries Service Southwest Fisheries Center NOAA Technical Memorandum NMFS The National Oceanic and Atmospheric Administration (NOAA) was organized in 1970. It has evolved into an agency which establishes national policies and manages and conserves our oceanic coastal, and atmospheric resources. It provides managerial, research, and technical expertise to produce practical services and essential information for the programs concerned with such resources. The National Marine Fisheries Service (NMFS) provides the United States with an integrated program of management, research, and services concerned about the protection and rational use of living marine resources for their aesthetic, economic, and recreational value. NMFS determines the 4 consequences of the naturally varying environment and human activities on living marine resources. NMFS provides knowledge and services to foster the efficient and judicious use of those resources. NMFS provides for domestic and for international management and conservation of these living resources of the sea. To carry out its mission, the organization also provides for communication of NMFS information. In addition to its formal publications, NMFS uses the NOAA Technical Memorandum series for informal scientific and technical publications. These documents are specialized reports that require multiple copies when complete formal review and editorial processing are not appropriate or feasible. The management and control of Technical Memorandums has been delegated to the Research Centers, Regional Offices, and corresponding staff offices within NMFS. Therefore, requests for copies of Technical Memorandums should be sent to the author or to the originating office for the material. c c NOAA Technical Memorandum NMFS SYNOPSIS OF BIOLOGICAL DATA ON THE GREEN TURTLE IN THE HAWAIIAN ISLANDS George H. Balazs National Marine Fisheries Service Southwest Fisheries Center Honolulu Laboratory Honolulu, Hawaii 9681 2 October 1980 U.S. DEPARTMENT OF COMMERCE Philip M. Klutznick, Secretary National Oceanic and Atmospheric Administration Richard A. Frank, Administrator National Marine Fisheries Service Terry L. Leitzell, Assistant Administrator for Fisheries iii Adult female Hawaiian green turtle basking on Trig Island at French Frigate Shoals. The small depth recorder attached to the carapace was used to measure maximum diving depth during the internesting interval. (Photograph by G. H. Balazs, June 1979.) V TABLE OF CONTENTS Page TNTRODUCTION ................................................................ 1 1. IDENTITY 1.1 Nomenclature and Taxonomy. ........................................ 2 1.2 Common Names...,....... ........................................... 4 1.3 Size Categories ................................................... 4 1.4 Tagging and Measuring ............................................. 4 2. DISTRIBUTION 2.1 Total Area........................................................ 6 2.2 Differential Distribution............................,,........... 7 2.21 Adults ...................................................... 7 2.22 Hatchlings, juveniles and subadults ......................... 8 FL 3. ECOLOGY AND LIFE HISTORY 3.1 Reproduction ...................................................... 9 3.11 Sexuality ................................................... 9 3.12 Maturity .................................................... '9 3.13 ~ting...................................................... 10 3.14 Fertilization. .............................................. 11 3.15 Nesting and habitat characteristics......................... 11 3.16 Reproductive cycles ......................................... 14 3.17 Eggs .......................................... "............. 15 a 3.2 Hatchling Phase................................................... 16 3.3 Juvenile, Subadult and Adult Phase................................ 17 3.31 Longevity ................................................... 17 3.32 Competitors ................................................. 18 3.33 Predators................................................... 18 3.34 Epizoics, diseases, abnormalities and injuries. ............. 20 3.4 Nutrition and Growth.............................................. 23 3.41 Food sources.........................,...................... 23 25 3.42 Feeding behavior.. .. .. .. .. .. .. .. .. .. .. *. .. .. 3.43 Growth rates................................................ 27 Vi Page L 3.5 Post-Hatchling Movements .......................................... 29 3.51 Dispersal and developmental migrations ...................... 29 3.52 Remigrations ................................................ 31 3.53 Navigation and orientation.................................. 32 3.6 Basking ........................................................... 34 4 . POPULATION 4.1 Structure......................................................... 38 a- 4.11 Sex ratio ................................................... 38 4.12 Size composition ............................................ 39 4.2 Abundance and Density ............................................. 40 c 4.3 Reproduction Rates ................................................ 41 4.4 Mortality ......................................................... 41 4.5 Recruitment ....................................................... 42 c 5 . EXPLOITATION 5.1 Historical Overview ............................................... 43 5.2 Commercial Catch Reports .......................................... 45 Y 5.3 Noncommercial Catch ............................................... 47 6 . PROTECTION AND MANAGEMENT 6.1 Regulatory Measures ................................................ 48 6.2 Management Practices and Options .................................. 49 6.21 Artificial stocking ......................................... 49 6.22 Predator control............................................ 50 6.23 Enforcement and education ................................... 51 6.24 Aquaculture ................................................. 51 a BIBLIOGRAPHY ................................................................ 53 SUBJECT INDEX............................................................... 98 vii LIST OF TABLES Page Table 1. Number of CheZonk tagged throughout the Hawaiian Archipelago since 1973......................... .............. 100 Table 2. Straight carapace length and width of adult female green turtles at French Frigate Shoals....................... 101 Table 3. Curved carapace length and width of adult female green turtles at French Frigate Shoals..................oe... 102 Y Table 4. Summary of growth rates and projected years to maturity for green turtles sampled at resident foraging areas in the Hawaiian Archipelago ..................................... 103 Table 5. Number of egg clutches laid by green turtles at East Island, French Frigate Shoals ................................ 104 Table 6. Internesting intervals of green turtles at East Island, French Frigate 105 Table 7. Results of 40 precounted egg clutches excavated and examined at East Island following the natural L emergence of hatchlings...... ................................ 105 Table 8. Number of nesting green turtles tagged and subsequently recovered at East Island, French Frigate Shoals, 1973-1979... 106 Table 9. Food sources recorded for green turtles in the Hawaiian Archipelago .................................................. 107 Table 10. Major food sources of green turtles in the Hawaiian Archipelago .................................................. 110 Table 11. Growth rates of Hawaiian green turtles released from captivity and raised in captivity............................ 111 Table 12. Growth rates of adult green turtles recovered at French Frigate Shoals since June 1973............................... 112 Table 13. Growth rates of Hawaiian green turtles captured from the wild and held for extended periods in captivity at Sea Life Park.................,...........................~~.o~~~~ 113 Table 14, Movements of Hawaiian green turtles in the main islands after being held in captivity for extended periods........... 114 c viii Page Table 15. Locations and numbers of tag recoveries documenting long distance migrations by adult green turtles in the Hawaiian Archipelago ..................................... 115 Table 16. Long distance migrations of adult Hawaiian green turtles recovered since June 1973...... ...................... 116 Table 17. Mean weights of turtles from the Hawaiian Islands reported as being commercially captured, 1948-1973. .......... 118 Table 18. Maximum numbers of green turtles seen basking at one time during surveys in the Northwestern Hawaiian Islands since 1950 ................................................... 121 Table 19. Tiger sharks , GaZeocerdo cuvier , captured at locat ions in the Hawaiian Archipelago where turtles were found to be prey items. ............................................ 122 Table 20. Monthly number of turtles sold in the Honolulu Fish Market, 1900, 1902-1904 ...................................... 123 Table 21. Kilograms and percent of turtle from the-Hawaiian Islands reported as being commercially captured by various fishing methods, 1948-1973 ........................................... 124 Table