Surveys of Sea Turtle Populations and Habitats in the Western Atlantic
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NOAA Technical Memorandum NMFS-SEFC-91 I O F C 0* 9- SURVEYS OF SEA TURTLE POPULATIONS AND HABITATS IN THE WESTERN ATLANTIC "A'rES 0* Archie Carr, Anne Meylan, Jeanne Mortimer, Karen Bjorndal, and Thomas Carr March 1982 U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Marine Fisheries Service Southeast Fisheries Center Panama City Laboratory 3500 Delwood Beach Road Panama City, Florida 32407-7499 NOAA Technical Memorandum NMFS-SEFC-91 Technical Memorandums are used for documentation and timely communication of preliminary results, interim reports, or special-purpose information, and have not received complete formal review, editorial control, or detailed editing. 0 ATMO SURVEYS OF SEA TURTLE POPULATIONS AND 0 7- HABITATS IN THE WESTERN ATLANTIC Q, .0 ;q)^jMENT Of Archie Carr, Anne Meylan, Jeanne Mortimer, Karen Bjorndal, and Thomas Carr March 1982 U.S. DEPARTMENT OF COMMERCE Malcolm Baldrigb, Secretary National Oceanic and Atmospheric Administration John V. Byrne, Administrator National Marine Fisheries Service William G. Gordon, Assistant Administrator for Fisheries Table of Contents Interim,Report, April 1980..*.*ooo .... *o.oo .... os..qp ... Introduction........ oooooo&ooooo*oo*oooooooo*ooo&* .... Procedure o,*oooosoooooosooooo*oo*oeooooooooooooooo*mooooossoooo 2 Nesting Ground Surveysoosoooesoooesooooosesooo6*oo.oo..o*. 2 Interviews and Other Sources of Data.ooo*ooooo&oo*oooooooo 5 Suggestions for Conducting Interviews ....... see ...... 5 Provisional Questionnaireeteas ...... we ..... so,..# .... 8 Regional Summaries United States ....... Florida.*.*..*..* ..... see, .... so ...... oo..*# ... o ...... 11 Alabama, Mississippi, Louisiana and Texas ............ 13 Mexico ... *so ... *4o .... *a#.* .... * .... o ... o...014 Tamaulipas .......... o ... o..oo; ..... 14 Veracruz ... o.o.o..o .*.15 Tabasco ...... o ..... ... 16 ..... *16 Yucatano* ......... o 17 Quintana Rooo ...... Belize .... **.so ... ............ d..o..19 Guatemalao..eo ... 00 ........ .. 19 Honduras...^ ...... o ....... ........ *:..20 Nicaragua*..*.. .... 21 Costa Rica ..... ... so.* ....... 22 Panama ... ....... so ..... #so ...... i ..... is ... * ... *23 Colombia ................... 0 ... be. 25 Venezuela .... *.so .... Trinidad 'and Tobago..*.*.* .... os..ioo.o ........ *26 so .... o.so..27 Caicos Islands ............ ............... 4 ...... 30 Jamaica..*..* ......... o ............ so ....... o .... o ....... *31 Dominican Republic ....... 000.0.0.0 ........... ..32 Haiti.,........... 9 ..................... .:::..33 Puerto Rico, Mona, Culebra Island Group, and Vieques .... o.34 U.S. and British Virgin Islands ....... o ................... 35 Guadeloupe* ......... ...... o o ....... o .... 36 Dominica ....... o o ......... o,o ....... so ........ *.*37 Martiniquee .... s ............ o ...... 0, ---o ... 39 St. Lucia .... o ................... 40 St. Vincent.** .... *.so ...... Grenada.o.o ........ o .... o .... o ... o.43 Literature Cited ... * .... o .... so .... #see** ........... o ..... * ... *45 Figures 1-13 Distribution of ecologic and developmental stages of five species of west Atlantic sea ttirtles..47-60 Figures 1-3 Green turtle .............................. 48-50 Figures 4-6 Hawksbill. 1 -.0.,0, .51-53 Figures 7-9 Loggerhead: ... Figures 10-12 Kemp's ridley ................. o ......... 57-59 Figure 13 Leatherback ..... o ............. o .............. o.60 Interim Report, August'1981 .......... too ... too ... ... 61 Introduction ...... 0 .................. to ............ 9 ...... * .... 61 Regional Summarieso ................ to-o ...................... * .... 62 Nicaragua ........ to .... to .... *.62 Costa Rica ............. ......... 64 Panama..,.o ............ o ..... ....... ooo....'o...-65 San Andres Archipelago ..... o ............. to too,....... 67 San Andr(;s and General.-o-tio ........ ^.o ... oo..^-io.o..68 Providencia .................... 0.*..0. o ..... o*70 Eas t So u^theas t Cays (Cour town C-Ays),. o 70 Albuquerque Cays (Southwest Cays)oo, .... t P. ..^71 Serrana Ba'nk.o .... o ... ............ : ...... o'. o7l Quitasudno Bank .... 72'' Roncador Cay ....... ............ ... :72 Leeward to ......... o ............. ....... 72 Los Roques, Venezuela..o..0 ... to ...... 0 ...... 00 ... 0.0s.-...73 Tables 1-6 ............ .............. ...... *** .... 75-82 Figures 1-9 .................................. .............. 83-92 PREFACE This is & preliminary report of a survey to assess population levels and identify critical habitats of the five-genera and six species of sea turtles I (Chelonia mydas, green turtle; Eretmochelys imbricata, hawksbill; Caretta caretta, loggerhead;-Lepidochelys keppi, Kemp's ridley; L. olivacea, olive T7Idley; ___ " Dermochelys coriacea, leatherback) that occur in the American Atlantic. Results of this investigation will provide grounds for subsequent efforts to determine recent'population changes and their causes and for plans by which the species can be graduated from their present endangered and threatened status. This report presents results of field research conducted by.,the Caribbean Conservation Corporation under two consecutive contracts with the National Marine I I Fisheries Service. The periods of the wo rk extended from May, 1978 through April, 1980, and'from May, 1980 through August, 1981. The data obtained came from aerial and ground surveys and from an exhaustive series of standardized interviews with all persons who seemed likely to contribute useful information on occurrence, ecology, density, and density trends in the local sea turtle populations. In some cases the same geographic area was surveyed more than once. Because these are interim reports, complete coverage of the literature on marine turtles of the Caribbean area was not attempted. Field personnel for the project consisted of: Karen Bjorndal, David Carr, Peggy Carr, Thomas Carr (field manager during the first quarter), Anne Meylan, Peter Meylan, Jeanne Mortimer (managing editor and cartographer, 1980 interim report), and Archie Carr (Principal Investigator). Special contributions to the survey were made by Larry Ogren, Guillermo Cuellar, and Argelis Ruiz. Lynda Whitaker served as recording secretary for the project. This report was prepared by the authors for the Southeast Fisheries Center, National Marine Fisheries Service, under Purchase orders 03-78-DO8-0025 and NA 80-GA-C-00071. 1 Surveys of Sea Turtle Populations and Habitats in the West Atlantic Interim Report to National Marine Fisheries Service April 1980 Introduction Although none of the species of sea turtles in the Caribbean has become extinct, all are represented by remnants of once extremely abundant popula- tions. The major decline in their numbers took place long before the current concern over endangered and threatened species. The changes that have occur- red during the last few decades are relatively minor, compared with those of previous centuries. Destruction of green turtle and hawksbill colonies, especially, began with the very earliest explorations and has continued for 300 years. The abrupt decline of Kemp's ridley came much later, but has been cataclysmic. Destruction of loggerheads and leatherbacks has been less dras- tic, but even they have been reduced or depleted over wide areas. This his- torical background of drastic reduction must be understood if existing popula- tions are to be given the appropriate attention that will avert continued losses. Efforts to assess west Atlantic sea turtle populations and the fac- tors involved in their survival and rehabilitation are essential. An important extension of our original work plan, one that ought to be part of any new phase of the West Atlantic Survey, is to recognize the vital importance of longshore current systems and weed-line shears as habitats to be surveyed - wherever this can be done without unreasonable outlay for ship time. An understanding of shear-line geography is critical to the search for the "lost" post-hatchling stage of sea turtle ecology, as are also the places and times at which the juveniles leave that stage and invade the benthic littoral habitats in which they mature. Until this information is available our knowledge of the life cycle is seriously incomplete, and effective conser- vation is handicapped. To achieve better knowledge of shear-line distribution and seasonality seems essential to an understanding of sea turtle ecology. Another important aspect of the biology and ecology of these turtles that should be investigated is their reaction to winter temperatures in the temperate zone extensions of their ranges. These areas should be searched for hibernation sites and other evidence of overwintering. As more is learned of the seasonal distribution of size groups, overwintering may prove to be increasingly likely in some populations. 2 The most important remaining geographic gaps in coverage of the,region we set out to investigate are the island of Cuba, parts of the Bahamas, the Honduranian Miskitia, the Nicaraguan mainland shore, the Guajira Peninsula of Colombia and Venezuela, and the smaller islands and banks of the western Caribbean. That Cuba and the Guajira will be adequately surveyed at any early date seems unlikely. Most of the other areas will be visited in new phases of the survey, however, and additional field work will be done at some of the nesting grounds to determine seasonal changes in density. -Work in Brazil projected in our original contract proposal was deferred because of word that Surinam and Brazil were