|Table of Contents|
Table of Contents
Chapter 1. Introduction
Chapter 2. Human use patterns
Chapter 3. Harvest rates and demographics of marine turtles
Chapter 4. Reproductive characteristics and cyclicity of green turtles on a foraging ground
Chapter 5. Assessment of harvest levels and their impact on marine turtle populations
Chapter 6. Management implications, recommendations, and research needs
Appendix A. Minimum number and (percent) of marine turtles captured in the region Autonoma del Atlantico Norte, Nicaragua for the periods February 1994 to January 1995 and December 1995 to April 1997
Appendix B. Minimum number of marine turtles captured by community in the region Autonoma del Atlantico Sur, Nicaragua
Appendix C. Minimum number of green turtles, chelonia mydas, landed at each site on the Caribbean Coast of Nicaragua from 1991 to 1996
Appendix D. Pearson correlation coefficients for ten body measurements of green turtles, chelonia mydas, harvested from the Caribbean waters of Nicaragua
Appendix E. Regression analysis of curved carapace length (CLN) against nine other body measurements of harvested green turtles, chelonia mydas, by sex from the Caribbean waters of Nicaragua
Appendix F. Minimum number of hawksbill, eretmochelys imbricata; loggerhead, caretta caretta; and leatherback, dermochelys coriacea, turtles reported captured and/or harvested in the Caribbean waters of Nicaragua from 1991 to 1996
Appendix G. Summary statistics of body size parameters for harvested hawksbill, eretmochelys imbricata, turtles
MARINE TURTLE FISHERY OF CARIBBEAN NICARAGUA:
HUMAN USE PATTERNS AND HARVEST TRENDS
CYNTHIA JEAN LAGUEUX
A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
I could not have completed this dissertation without the technical assistance,
financial and emotional support of numerous people throughout these many years. With
deep appreciation and respect, I thank the members of my doctoral committee, Kent
Redford (Chair), Lou Guillette (acting Co-Chair), Jeanne Mortimer, Richard Bodmer,
George Tanner, and Lyn Branch. I am honored to have the opportunity to know and
work with each of them and I thank them for their inspiration, leadership, and support. A
special thank you to J. Mortimer for her tireless effort in improving my writing skills.
I would like to extend my sincerest appreciation to the people of the Caribbean
coast of Nicaragua who allowed me into their lives, if only for a short period, and without
whose cooperation and trust this study would not have been possible. I especially thank
the people of the communities of Awastara, Dakra, Rio Grande Bar, Sandy Bay, Sandy
Bay Sirpi, Set Net, and Tasbapaune for their friendliness, patience, and generosity in
sharing their knowledge, food, and homes with me.
I am indebted to the marine turtle butchers of Puerto Cabezas: Cecil Clark,
Winston Martinez, Cristina Ramos, Carolina Guillermo, David Kingsman, Nora Pablo,
Idincio Kingsman, Norma, Justis, Clasida, Aaron, Tano Chow, Marcia Hammer, Jack
Morris, Victoria Flores, Ilario Flores, Virginia and Stanford Humphries, Rosa and Raisil
Wilson, Sam Peralta, Norma Blair, Rina Ramos, Martin Martinez, Alberto Renales, and
Mejia. Night after night, they allowed me to measure and weigh their animals, and I am
grateful for their patience as I removed tissue samples while they butchered them. I am
especially thankful to have worked along side Cecil Clark, Alejandro Clark (Julio), and
Winston Martinez, who, with their many years of experience, skill, and knowledge,
taught me much about marine turtles and their anatomy.
I appreciate the dedication and hard work of the numerous community data
collectors. In many aspects, the success of this study and the strength of the conclusions
are based on their hard work, dedication, and conscientious manner in which they
collected the harvest data. I thank each of them: Rodrigo Renales, Eupreciano
Hoppington, and Orlando Grantt of Awastara; Aida Morris and Ermicinda Pong of
Dakra; Waldemar Brooks, Silvio Perera, and Guillermo Recta of Sandy Bay; Ejan Smith,
Emelina Smith, and Stanley Martinez of Sandy Bay Sirpi, Lorna Churnside of Rio
Grande Bar; Riley Carlos and Olivia Wilson of Tasbapaune; Francela Thomas of Set Net;
Joseph Humphries (Haulover) of Corn Island; and Cecil Clark, Julio Clark, Winston
Martinez, and Denis Castro of Puerto Cabezas. I especially would like to acknowledge
the work of Ejan Smith with whom I enjoyed many visits and conversations about sea
turtles. Ejan was lost at sea in December 1996, he is painfully missed.
I also thank Denis Castro for the many hours we have spent discussing the use and
conservation of natural resources on the Caribbean coast of Nicaragua, for his hard work,
his collaboration during the many weeks we have spent visiting communities along the
Nicaragua coast, and for sharing with me insight into his culture. I appreciate the
expertise of D. Castro for translating my dissertation abstract into Miskitu and Olga
Montenegro for translating it into Spanish.
I would like to acknowledge the many friends I made while living in Puerto
Cabezas with whom I shared cold beers, softball and baseball games, and I thank them
for their concern and care when I became ill. In particular, I thank Flor Francis, Lilia and
Nelbert Taylor, Berit Stokstad, Enrique and Erlinda Obregon, Ricky Newball, and Ana
Peachy for making my experiences in Puerto Cabezas memorable.
I am grateful to my very dear friends in Managua, Dofia Tulita Garcia, Carmen
Labr6, and Carmen Irene and Alejandrina (Alex) Hildeprandt for opening up their home
to me. They always welcomed me with good home cooking and a place to relax. I
appreciate their patience even when I filled up their home with many trunks of equipment
and supplies each time I entered the country and with the same number of trunks filled
with turtle bones, blood, urine, feces, and reproductive tracts each time I exited the
There have been several key people throughout the years whose technical
knowledge and skills were crucial in the completion of my dissertation: I would like to
thank my very own personal computer guru, Noel Ocampo, who, for the price of
chocolate, kept my computer up and running; Howard Kochman, my SAS mentor, for
sharing his priceless knowledge of SAS and ANCOVA's; Tim Gross for assisting me in
purchasing supplies and equipment; Cathy Cox, Andy Rooney, and Drew Cramin for
teaching me histological methods; and Jay Harrison and Scott Kowalski of the Institute of
Food and Agriculture Sciences, University of Florida, for their statistical consultations.
A special thank you to Cathi Campbell for assisting me with collecting turtle
samples, conducting statistical analyses, writing SAS programs, solving computer
software quirks, and editing drafts of the dissertation. I am also thankful to her for the
innumerable discussions about sea turtle ecology, human use of natural resources, and
conservation biology that we have had.
Numerous personnel of the Servicio de Areas Silvestres y Fauna, Ministerio del
Ambiente y Recursos Naturales (MARENA), Managua assisted me in obtaining research
permits. Staff of the CITES (Convention on International Trade in Endangered Species
of Wild Fauna and Flora) office in Managua and Washington D.C. were always helpful
and prompt in assisting me to obtain export and import permits. I am grateful to Cecil
Clark of Puerto Cabezas, Nicaragua; the Centro de Investigaciones y Documentaci6n de
la Costa AtlIntica, Bluefields, Nicaragua; and the Caribbean Conservation Corporation,
Gainesville, Florida for providing me with their unpublished harvest data.
I am indebted to the following organizations without whose financial support this
study would have remained only an idea: Wildlife Conservation Society, Inter-American
Foundation, Chelonian Foundation, The Nature Conservancy, Sigma Xi, Caribbean
Conservation Corporation, and the U.S. Agency for International Development.
I am very grateful to my mother, Lillian Minarik, who has always believed in me
and has been financially and emotionally supportive through all my endeavors.
Regardless of the project, she has always been interested in what I was doing and willing
to jump in and assist, from conducting necropsies on decomposing marine turtle carcasses
to assisting throughout the night with the collection of turtle blood, urine, feces, and
reproductive tracts. Her assistance in data entry and proofing were invaluable. I also
thank my father, Robert Minarik, for his financial support during the writing of the
And finally, I thank my friends and colleagues for their stimulating conversation
and support. Over the years, I have come to realize that I could not have attempted nor
completed this degree alone and my accomplishment is a tribute to everyone who
believed in me. Without all of the many components coming together at the right time
and place the dissertation which you are about to read would not be in front of you.
TABLE OF CONTENTS
ACKNOWLEDGMENTS ................................................ ii
A B STRA CT ............................................................ x
RESUM EN .......................................................... xii
K LU TKA ............................................................ xiv
1 INTRODUCTION .............................................. 1
Sea Turtles as a Resource ...................................... 1
Worldwide Status of Sea Turtles ........................... ... 2
Historical Harvest of Sea Turtles, Except Nicaragua................. 3
Historical Harvest of Sea Turtles from Caribbean Waters of Nicaragua 20
Marine Turtles and the Nicaragua Fishery ....................... 23
2 HUMAN USE PATTERNS ..................................... 27
Introduction ............................................... 27
M ethods .................................................. 31
Results ................................................... 39
Discussion ................................................ 54
Conclusions ............................................... 64
3 HARVEST RATES AND DEMOGRAPHICS OF MARINE TURTLES ... 66
Introduction ............................................... 66
M ethods .................................................. 69
Results ................................................... 77
Discussion ................................................ 96
Conclusions .............................................. 111
4 REPRODUCTIVE CHARACTERISTICS AND CYCLICITY OF GREEN
TURTLES ON A FORAGING GROUND ......................... 113
Introduction ................................... .......... 113
M ethods ................................................. 115
Results .................................................. 120
D discussion ............................................... 135
Conclusions .............................................. 142
5 ASSESSMENT OF HARVEST LEVELS AND THEIR IMPACT ON
MARINE TURTLE POPULATIONS ............................ 144
Introduction .............................................. 144
M ethods ................................................. 148
Results .................................................. 149
Discussion ............................................... 150
Conclusions .............................................. 160
6 MANAGEMENT IMPLICATIONS, RECOMMENDATIONS, AND
RESEARCH NEEDS .......................................... 162
Implications for Managing the Marine Turtle Fishery .............. 162
Management Recommendations ............................. 167
Recommendations for Future Research ........................ 171
A MINIMUM NUMBER AND (PERCENT) OF MARINE TURTLES
CAPTURED IN THE REGION AUTONOMA DEL ATLANTICO
NORTE, NICARAGUA FOR THE PERIODS FEBRUARY 1994 TO
JANUARY 1995 AND DECEMBER 1995 TO APRIL 1997. ......... 173
B MINIMUM NUMBER OF MARINE TURTLES CAPTURED BY
COMMUNITY IN THE REGION AUTONOMA DEL ATLANTICO
SUR, NICARAGUA ........................................... 176
C MINIMUM NUMBER OF GREEN TURTLES, CHELONIA MYDAS,
LANDED AT EACH SITE ON THE CARIBBEAN COAST OF
NICARAGUA FROM 1991 TO 1996 ............................. 182
D PEARSON CORRELATION COEFFICIENTS FOR TEN BODY
MEASUREMENTS OF GREEN TURTLES, CHELONIA MYDAS,
HARVESTED FROM THE CARIBBEAN WATERS OF NICARAGUA. 185
E REGRESSION ANALYSIS OF CURVED CARAPACE LENGTH
(CLN) AGAINST NINE OTHER BODY MEASUREMENTS OF
HARVESTED GREEN TURTLES, CHELONIA MYDAS, BY SEX
FROM THE CARIBBEAN WATERS OF NICARAGUA ............. 186
F MINIMUM NUMBER OF HAWKSBILL, ERETMOCHELYS
IMBRICATA; LOGGERHEAD, CARETTA CARETTA; AND
LEATHERBACK, DERMOCHELYS CORIACEA, TURTLES
REPORTED CAPTURED AND/OR HARVESTED IN THE
CARIBBEAN WATERS OF NICARAGUA FROM 1991 TO 1996. ....187
G SUMMARY STATISTICS OF BODY SIZE PARAMETERS FOR
HARVESTED HAWKSBILL, ERETMOCHELYS IMBRICATA,
TURTLES ................................................... 188
LITERATURE CITED ................................................. 189
BIOGRAPHICAL SKETCH ............................................. 214
Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy
MARINE TURTLE FISHERY OF CARIBBEAN NICARAGUA:
HUMAN USE PATTERNS AND HARVEST TRENDS
Cynthia Jean Lagueux
Chairperson: Kent H. Redford, Ph.D.
Major Department: Wildlife Ecology and Conservation
The Miskitu Indian marine turtle fishery of Caribbean Nicaragua was studied to
determine human use patterns and harvest trends in the fishery, and to evaluate its impact
on marine turtle populations. Specific objectives of the study were to 1) characterize
human use patterns, 2) quantify the number of animals harvested annually, 3) describe the
size and sex of harvested animals, 4) describe the reproductive cycle of green turtles
(Chelonia mydas), 5) evaluate the impact of the fishery on marine turtle populations, and
6) provide management and research recommendations.
Green turtles are targeted in the fishery, hawksbills (Eretmochelys imbricata) are
harvested opportunistically, and loggerheads (Caretta caretta) and leatherbacks
(Dermochelys coriacea) are captured incidentally in nets set for green turtles. Marine
turtles are a source of protein, provide income through the sale of meat and tortoiseshell,
and most recently, used as bait in other fisheries. Current minimum annual harvest levels
of green turtles are 10,000 to 11,000 animals, levels that are as high or higher than they
have probably ever been for this coast. The majority of harvested green turtles are
juvenile females. Like mature females, at least some of the mature males are not annual
breeders. Large juveniles and adult hawksbills, loggerheads, and leatherbacks are also
captured, although harvest levels are much lower than for green turtles.
Indications that green turtles are overharvested are the decrease in mean length
and mass of harvested animals, and decrease in the mesh size of nets used. Population
modeling studies of other long-lived, slow-maturing species indicate that increased
mortality ofjuveniles and adults affect population growth the most. Results of this study
do not indicate conclusively that marine turtle populations in Nicaragua are
overharvested. Based on the magnitude of the green turtle fishery and its focus on large
juveniles and adults, however, there is clearly cause for concern.
The development of a co-managed marine turtle fishery is recommended.
Restrictions on the number, size, and sex of animals harvested, as well as, other
recommendations to manage the fishery are made. Recommendations for future research
on characteristics of marine turtle populations in the region are also made.
Resumen de la Disertaci6n Presentada a la Escuela de Graduados
de la Universidad de Florida en Cumplimiento Parcial de los
Requisitos para el Grado de Doctor en Filosofia
PESQUERIA DE TORTUGAS MARINAS DE LA COSTA CARIBE
DE NICARAGUA: PATRONS DE USO HUMANS
Y TENDENCIES DE LA COSECHA
Cynthia Jean Lagueux
Asesor Principal: Kent H. Redford, Ph. D.
Departamento: Ecologia y Conservaci6n de Vida Silvestre
Se estudi6 la pesqueria de tortugas marinas entire los indigenas Miskitu en la costa
caribe de Nicaragua, con fin de determinar los patrons de uso human y las tendencies
en la cosecha y para evaluar su impact en las poblaciones de tortugas marinas. Los
objetivos especificos del studio fueron 1) caracterizar los patrons del uso human, 2)
cuantificar el numero de animals cosechados anualmente, 3) describir el tamafio y sexo
de los animals cosechados, 4) describir el ciclo reproductive de las tortugas verdes
(Chelonia mydas), 5) evaluar el impact de la pesqueria en poblaciones de tortugas
marinas, y 6) dar recomendaciones para el manejo e investigaci6n.
Las tortugas verdes son el blanco de la pesqueria, mientras que las carey
(Eretmochelys imbricata) son cosechadas en forma oportunista y los cabezones (Caretta
caretta) y baulas (Dermochelys coriacea) son capturados incidentalmente en las redes
puestas para las tortugas verdes. Las tortugas marinas son una fuente de protein,
proporcionan ingresos por venta de la came y el caparaz6n, y mas recientemente son
usadas como camrnada en otras pesquerias. Los actuales niveles anuales minimos de la
cosecha de tortugas verdes son de 10.000 a 11.000 animals, probablemente los niveles
mas altos que hayan existido para esta costa. La mayoria de las tortugas verdes
cosechadas son hembras juveniles. Igual que las hembras maduras, al menos algunos de
los machos adults no se reproducen anualmente. Los juveniles grandes y adults de
carey, cabezones y baulas tambien son capturados, aunque los niveles de cosecha son
much mas bajos que los de tortugas verdes.
Indicaciones de que las tortugas verdes son sobre cosechadas son la disminuci6n
en la longitud media y el peso de los animals cosechados y la disminuci6n en el tamaflo
del ojo de las redes usadas. Estudios que usan models de poblaci6n para otras species
de larga vida y maduraci6n lenta indican que la mortalidad de juveniles y adults es el
factor que mas afecta el crecimiento de la poblaci6n. Los resultados de este studio no
indican en conclusion que las poblaciones de tortugas marinas en Nicaragua son sobre
cosechadas. Sin embargo, con base en la magnitude de la pesqueria de tortuga verde y su
concentraci6n en juveniles grandes y adults, existe claro motive de preocupaci6n.
Se recomienda el desarrollo de una pesqueria co-manejada de las tortugas
marinas. Tambi6n se recomiendan restricciones en el n(mero, tamafno y sexo de los
animals cosechados, asi como otras sugerencias para el manejo de la pesqueria.
Igualmente se hacen recomendaciones para investigaciones futuras sobre las
caracteristicas de las poblaciones de tortugas marinas en la regi6n.
Tanka plikanka ulbanka Kunhku kum Skul tnata alkan ra
Marikanka kum daukan sa pura luanka ai skul ka ra tanka Florida
Universidad kara Daktar takaia dukiara tanka pliki kaiki brabrira kaia mata
LIH MISKANKA NICARAGUA LALMA KABUKA RA
YUS MUNANKA TNATKA BARA ALKANKA TANKA
Cynthia Jean Lagueux
Lih mairin kati 1998
Lalka: Kent H. Redford, Daktar
Waild nani raiaka an watla bila kan kahbaia aslika
Miskitu nani lih yus munanka tnatkaba tanka pliki kaikan kan Nicaragua lalma
kabuka unra, yus munanka tnanka bara alkanka tnatka ba wal tanka briaia dukiara, baku
sin dia pitka kat sauhkanka brih auiaba lih aslika ra. Dia mihta nitkan naha tanka pliki
kaikaia: 1) yus munan tnaka ba tanka briaia, 2) nahki pitka mani bani alkiba, 3) within ai
pawanka pitka alki ba tilara waihka baku mairin ba tanka kaikaia, 4) lih sahwanka tanka
ba kau briaia dukiara, 5) dia pitka kat sauhki aula miskanka tnatka ba bui, 6) kupia
kraukanka iaia yus munanka tnatka kum brih waia ba dukiara bakusin ai tanka pliki
Mamiskra nani brinka paliba lih (Chelonia mydas) sakuna axbil (Eretmochelys
imbricata) sans ra alkisa, lagrit (Caretta caretta), bara lih siksa (Dermochelys coriacea)
ba wal alkisa kuna lih tanka kahbuia ba tilara accident ra. Kabu lih ka ba aunhka ba
dukiara yus munisa, baku sin winka ba atki ilpka brisa, baku sin ai miskanka nani tnatka
walara yus munisa. Lih kau wiria alkiba 10,000 wina 11,000 kat alkisa, naha na aima
wala nani wal prakbia kaka nanara kau alkisa, baha pitka alkiba wina aihkika ba mairin
tiara lupia kau alkisa, tila bara mairin aiapra kum kum alkisa, bara sin waihka nani kum
kum ba mani bani sip alkras sa. Baku sin lagrit bara lih siksa wahma an almuk alkisa.
Lih ba uba alki ba tanka mamrikisa, ai paunkara kaikaia sipsma ai pawrikara bara
piu luia bani tan nakra kau sirpi daukisma bara. Tanka pliki kaiki naniba tnatka kum wal
mamrikisa daiwan nani rayaka yari briba wihkara ai kiamka sakisa bara man wahma an
tiara nani ikisma bara ai daknika pawanka ra sauhkisa. Naha tanka pliki kaikan na mai
wiras sa Nicaragua lih aslika ba tankas yus munanka kum barasa. Sakuna aima banira lih
aialkra nani kau ailal barasa baku sin lihka alkismaba wahma, tiara nani kau alkisa, baha
mihta sarka kum barasa lih aslika pawanka ba dukiara.
Baha mihta kupia kraukisa lih ba tankira miskaia wakanka tnatka kum wal. Baku
sin lih alkaia ba pitka kum bara kaiasa bara ai pawanka pitka kum sin bara kaiasa baha
pitka baman alkaia, bara sin waihka apia kaka mairin baman alkaia laka bara kaiasa. La
tnatka wala nani sin bara kaia sa lih yus munanka ra, bara sin lih raiaka tanka an ai
daknika pawanka tanka ba briaia wan klauna tasbaiara.
Humans use natural resources for food, shelter, medicine, tools, pets, curios,
barter, and as a source of income with which to procure other goods and services.
Current and historical uses of natural resources for subsistence and trade have been well
documented in the literature (e.g., Robinson and Redford 1991, 1994; Jorgenson 1993;
Rose 1993, 1996; Bodmer 1994; Bodmer et al. 1994; Jenkins and Broad 1994; Bissonette
and Drausman 1995; Jenkins 1995; Townsend 1995; Vincent 1996; Freese 1997). Use of
sea turtles dates back to early humans with the discovery of what appear to be green turtle
(Chelonia mydas) bones from excavations of Borneo caves (Harrisson 1962a, b, 1967),
and tortoiseshell products from hawksbill turtles (Eretmochelys imbricata) dating back to
the Han dynasty of China, beginning approximately 200 B.C. (Parsons 1972). The trade
in hawksbill shell dates back to the 15th century B.C. (Parsons 1972).
Sea turtles and their eggs have provided humans with a dependable resource for
thousands of years. Nesting females and their eggs are highly vulnerable to harvesting,
particularly the eggs, because they are an easy and relatively risk-free resource to exploit.
Sea turtle eggs, as well as nesting females, can be a long-term, predictable resource for
humans because 1) turtles nest on their natal beaches, 2) females are iteroparous, 3) most
species nest in relatively dense numbers, 4) nesting occurs seasonally (some species nest
year-around at some locations), and 5) several species can nest on the same beach during
different times of the year.
Unlike most other marine resources sea turtles can be kept alive, out of water, for
weeks and thus provide humans with a dependable source of fresh meat for prolonged
periods. Although nesting females and their eggs are more accessible for harvesting,
animals can also be captured in the water, however, more skill and equipment are
required. Some sea turtle species congregate on foraging grounds where they feed on
sessile prey, assemble offshore of their nesting beaches, or are predictable in their
migratory routes to and from the nesting beach. The concentration and predictability of
animals at known in-water locations during various times of the year or during their
lifespan makes them nearly as accessible to harvesting as nesting females and their eggs.
Worldwide Status of Sea Turtles
The current status of sea turtle populations worldwide is indicated by the
threatened status of the seven extant species (IUCN 1996). Overharvest of animals and
their eggs for human use, incidental capture, and habitat loss and degradation due to
coastal development are some of the primary causes of worldwide population declines
(e.g., Bjomdal 1982; National Research Council 1990; Eckert 1995; IUCN 1997;
Lutcavage et al. 1997). Currently, the international sale of sea turtles and their products
is illegal among the 142 (as of September 1997, Anon. 1997) signatory nations of the
Convention on International Trade in Endangered Species of Wild Fauna and Flora
(CITES). All seven species of sea turtles are listed under Appendix I, species threatened
with extinction (CITES 1992).
Historical Harvest of Sea Turtles, Except Nicaragua
The harvest of sea turtles for their meat, shell, oil, and calipee, and their eggs has
occurred for thousands of years, probably since hominids encountered female turtles,
their eggs, and hatchlings on coastal beaches. Human impact on turtle populations prior
to large-scale commercialization is unknown, however, population declines are well-
documented once exploitation for commercial purposes began (Ingle and Smith 1949;
Carr 1954; Parsons 1956, 1962, 1972; Rebel 1974; Cato et al. 1978; Bjomrndal 1982; Dodd
1982; King 1982; Milliken and Tokunaga 1987; Meylan 1997a). Although the eggs of all
seven sea turtle species are in demand, green and hawksbill turtles have received the
greatest pressure in both numbers of animals harvested and duration of exploitation
(Hornell 1927; Ingle and Smith 1949; Carr 1954; Parsons 1956, 1962, 1972; Freeman-
Grenville 1962; Rebel 1974; Cato et al. 1978; Bjomdal 1982; King 1982; Milliken and
Tokunaga 1987; Meylan 1997a). Tortoiseshell from hawksbill turtles was among the
items in demand and sought after by early civilizations (Parsons 1972). It carried prestige
and indicated wealth among the upper class. Cleopatra's bathtub was reportedly made
from hawksbill shell (Parsons 1972). Throughout various periods in history and for
shorter periods of time, the loggerhead (Caretta caretta), olive ridley (Lepidochelys
olivacea), Kemp's ridley (Lepidochelys kempi), leatherback (Dermochelys coriacea), and
flatback (Natator depressus) turtles have been in demand for their skin, oil, and meat
(Bjorndal 1982; Ross 1982). In addition to direct take, in-direct human-induced
mortalities also occur (National Research Council 1990; Lutcavage et al. 1997).
It is necessary to have, at least, a general awareness of the extent of historical and
contemporary levels of direct and in-direct take on sea turtle populations to avoid the
shifting baseline syndrome. This syndrome occurs when scientists view the baseline of
stock size or species composition from the start of their careers and not from a historical
perspective (Pauly 1995; Sheppard 1995). In addition, knowledge of the historical
decline of sea turtle populations worldwide provides a perspective with which to view
current population levels. Thus, the following section is a compilation of historical sea
turtle exploitation worldwide, except for Nicaragua and resulting population declines by
species and geographic region. The exploitation of sea turtles from Nicaragua will be
Mediterranean and East AtlanticRegions
Due to overexploitation, marine turtle populations off the coast of Israel and
Turkey have declined dramatically since the end of World War I (WWI) (Sella 1982). At
the peak of the season in the mid-1930s, an estimated 30,000 green and loggerhead turtles
were captured offshore of northern Israel (Sella 1982). Hornell (1934 cited in Sella 1982)
reported the export of 2,000 turtles a year from Palestine to Egypt. Between 1952 and
1965, up to 15,000 green and loggerhead turtles were harvested off the Turkish coast,
processed and the product sent to Europe (Sella 1982). Due to a decline in harvest rates
by the mid- 1960s the center of the fishery moved to another location along the coast and
by 1965 more than 10,000 turtles, mostly greens, were captured (Sella 1982).
By 1967, in Madeira, an estimated 1,000 loggerheads were killed annually,
primarily for human consumption and as wall hangings for the tourist trade (Brongersma
1982). By 1979, an estimated 2,000 loggerheads were killed annually and the primary
market had shifted to the tourist industry (Brongersma 1982).
In 1835, on Ascension Island, up to 40 or 50 green turtles were harvested from the
nesting beaches in a single night with an annual harvest of more than 2,500 animals
(Anonymous cited in Parsons 1962). In the 1840s and 1850s, between 600 and 800 green
turtles were harvested annually (Colonial Office Reports cited in Parsons 1962). By the
1920s, an average of 60 turtles a year were exported and by 1932 no mention of exports
were reported (Colonial Office Reports cited in Parsons 1962).
West Indian Ocean Region
Sea turtle populations in Tanzania have probably been reduced since prehistory
(Frazier 1982a). From the late 1800s until recently, Zanzibar was a major exporter of
tortoiseshell, however, the scutes originated from throughout the Indian Ocean and were
exported to Europe and Asia via Zanzibar (Frazier 1982a, b). Two thousand years of
exploitation have decreased the number of green and hawksbill turtles on the Kenya and
Somalia coasts (Parsons 1962; Frazier 1982a). In 1951, a turtle soup cannery was opened
in Kenya, and by 1954, an estimated 200 turtles were captured annually to supply the
cannery (Parsons 1962). From 1954 to 1959, 1,000 to 1,500 live turtles were exported
annually from Kenya to England (Parsons 1962). In Mauritius, sea turtles no longer nest
due to overexploitation (Frazier 1982b; Hughes 1982). In Madagascar, only the
hawksbill is exploited for export, however, the green, loggerhead, olive ridley, and
leatherback turtles are exploited mainly for local consumption (Hughes 1982).
Tortoiseshell has been an important export for Madagascar from 1613 to the early 1970s
(Hughes 1975). From the mid-1800s to the mid-1900s, a minimum of 1,600 adult
hawksbills were harvested annually (Hughes 1973, 1975). By WW I, tortoiseshell
exports declined sharply and by the mid-1970s annual exports were around 250 kg
(approximately 100 animals) (Hughes 1975). Based on a survey of the southwest coast of
Madagascar, Hughes (1971) calculated that over 13,000 turtles were harvested annually,
50% of the harvest comprised green turtles and the remainder of the catch distributed
approximately equally among loggerheads, hawksbills, and olive ridleys.
The harvest of green and hawksbill turtles from the Republic of Seychelles has
occurred since its discovery by Europeans in 1609 (Parsons 1972; Frazier 1982a;
Mortimer 1984; Stoddart 1984) and the decline of green turtles probably began in the late
1700s (Mortimer 1984) and hawksbills by the 1860s (Homell 1927). In 1780, 454 to 907
kg of hawksbill shell were harvested, and from 1893 to 1925, 42,727 kg of tortoiseshell
(z 30,500 animals) were exported (Homell 1927). From 1893 to 1968, Stoddart (1984)
reports the export of 60,780 kg of tortoiseshell (= 45,000 animals).
Green turtles in the Seychelles have been in demand for their meat, calipee, oil,
eggs, blood (drunk as a health tonic), shell, cawan (primarily plastron but also carapace
scutes), and bones (Homrnell 1927; Frazier 1975; Mortimer 1984). As early as 1860,
concern was expressed over the enormous numbers of green turtles killed for their cawan
(Hornell 1927). The most drastic decline in green turtles began in the early 20th century
(Hornell 1927; Mortimer 1984). From 1907 to 1909, Homrnell (1927) reported
approximately 20,500 green turtles were harvested. Between 1923 and 1925,
approximately 14,000 green turtles were harvested for only their calipee (cartilaginous
tissue located between the belly plates) and the remains of the animals were left on the
beach to rot (Hornell 1927; Parsons 1972). Indications that the population in the
Seychelles was in decline was the decrease in nesting females, decrease in the number of
animals harvested, and a decline in the heaviest animals (Homell 1927).
Between 4,000 and 5,000 sea turtles were captured annually in the southern Indian
state of Tamil Nadu, the time period was not given (Kar and Bhaskar 1982). Of 5,000
olive ridley egg clutches laid along a 50 km stretch of beach in Tamil Nadu,
approximately 90% were harvested by humans or predated by Canis spp. (Whitaker 1977
cited in Kar and Bhaskar 1982). Prior to 1975, the state government of Orissa sold
permits to collect approximately 2 million olive ridley eggs/yr (z= 100 eggs/clutch), which
were sold locally, regionally, and in Calcutta (Bustard 1980; Kar and Bhaskar 1982).
During a three month period, in 1978/1979, West Bengali fishers harvested over 21,000
olive ridleys in front of the Orissa nesting beach (Biswas pers. com. to Kar and Bhaskar
1982). During the 1981/1982 nesting season, an estimated 90,000 olive ridleys were
harvested, and during the 1982/1983 season, an estimated 10,000 ridleys were landed in
West Bengal and transported inland for sale (Silas et al. 1983). Due to overharvest for
tortoiseshell, hawksbills have been extirpated from the south coast of Sri Lanka (Frazier
At one time, five species of sea turtles were found in Thailand, and all were
exploited for their eggs. From the period 1963 1966 to the period 1972 1973, a 70%
decrease occurred in the number of eggs collected annually at one site (Polunin 1975;
Settle 1995). Today, green, hawksbill, olive ridley, and leatherback populations are
seriously reduced and the loggerhead is believed to be extirpated (Polunin 1975;
Mortimer 1988; Settle 1995).
The Rantau Abang leatherback rookery in the State of Terengganu, Malaysia, is
well known for its once large numbers of nesting leatherback turtles. Today, they are
critically endangered. In the late 1950s, an estimated 2,000 females laid approximately
10,000 egg clutches annually (Mortimer 1990). Since the 1950s, the nesting population
has declined steadily and catastrophically. A 1978 survey reported egg yields from
leatherbacks had declined 34% since 1956 (Siow and Moll 1982). In 1989, fewer than
200 egg clutches were laid, a 98% decrease in nesting activity (Mortimer 1990; Chan and
Liew 1995). In recent years, no more than 20 females nested annually (Mortimer pers.
com.). During the 1989 nesting season, Mortimer (1990) reports that as many as 1,000
tourists viewed a single nesting female. This catastrophic decline in nesting females is
attributed to a combination of factors, perhaps the most important being the nearly 100%
harvest of leatherback eggs laid during most of the present century but also adult
mortality caused by entanglement in fishing gear.
In addition to the leatherback rookery in the State of Terengganu, there is also
green, hawksbill, and on occasion olive ridley nesting (Siow and Moll 1982; Mortimer
1991). Between 1956 and 1978, green turtle egg production at Terengganu has declined
between 43% and 57%, (Siow and Moll 1982; Limpus 1994, 1997). The largest
concentration of green and hawksbill nesting in Terengganu occurs on Pulau Redang
Island (Mortimer 1991). Prior to 1984, nearly 100% of the green and hawksbill eggs laid
were collected for human consumption (Mortimer 1990). Since the late 1950s, declines
in the number of green, olive ridley, and hawksbill eggs laid in Terengganu ranged
between 52% and 85% (Mortimer 1990).
In 1839, on Talang Talang Kechil Island, Sarawak (one of three Sarawak islands
known for green turtle nesting) five to six thousand green turtle eggs were collected every
morning, the duration of this harvest rate was not reported (Hendrickson 1958; Keppel
1847 cited in Harrisson 1962a). By the mid-19th century, sections of beach were leased
by the government and nearly 100% of the green turtle eggs laid were collected
(Harrisson 1951, 1962b; Hendrickson 1958). Since 1927, there has been a > 90% decline
in egg production on Sarawak's turtle islands (Harrisson 1962b; Limpus 1994, 1997).
On Sabah, from 1947 to 1978, there has been more than a 50% decline, from
706,960 eggs (z 6,670 clutches) in 1947 to 322,102 eggs (z 3,039 clutches) in 1978, in
the number of green turtle eggs laid (Harrisson 1964, 1966, 1967; de Silva 1982; Limpus
1994). From 1951 to 1985, the green turtle nesting population of the Sulu Sea Turtle
Islands of Sabah, Malaysia/Philippines has declined > 75% and possibly as much as 90%
In Indonesia, between 1975 and 1978, an average 7,531 1,275 turtles/yr (species
not reported) were exported to Japan, Singapore, and the United States (Polunin and
Sumertha Nuitja 1982; Suwelo et al. 1982). An estimated 10,000 juvenile hawksbills
were captured annually from Sulawesi, and from 15,000 to 20,000 juvenile hawksbills
were captured annually from Sumatra, duration of the harvest was not given (Kajihara
1974 cited in Polunin and Sumertha Nuitja 1982). From the Java, Flores, and Banda seas,
approximately 5,000 adult hawksbills were captured annually prior to 1971 and 30,000
adults were captured annually after 1972 (Kajihara 1974 cited in Polunin and Sumertha
Nuitja 1982). During 1988 and 1989, over 1.5 tones ofbekko (Japanese term for
hawksbill shell) were exported in violation of CITES to Hong Kong, Taiwan, and
Singapore (Barr 1992). From 1934 to 1984, green turtle egg production declined more
than 80% (Limpus 1994). Barr (1992) estimated 7 to 9 million sea turtle eggs are
harvested annually in Indonesia, essentially 100% of the eggs laid.
One of the largest landings of green turtles in the world occurs in Bali (Barr 1992;
Limpus 1994, 1997). By 1950, local sea turtle populations around Bali were seriously
depleted (Sumertha Nuitja 1974 cited in Polunin and Nuitja 1982). From 1968 to 1970,
Sumertha Nuitja (1974 cited in Polunin and Nuitja 1982) reported the consumption of
28,800 turtles in two districts of Bali. In 1973, a Balinese company exported 5,000 to
6,000 stuffed sea turtles and leather from an additional 3,000 turtles each month (Polunin
1975). More than 30,000 turtles harvested annually from throughout the Indonesian
archipelago were landed in Bali at the height of the trade, no date was provided (Barr
1992; Limpus 1997). In the late 1980s, the World Wildlife Fund estimated the total
harvest of green turtles in Indonesia at 50,000 (Limpus 1997). In 1990, Greenpeace
investigators reported at least 21,000 sea turtles landed in southern Bali, although the
Indonesian government claimed harvest levels had decreased to approximately 10,000 to
15,000 animals annually (Barr 1992). Currently, 25,000 sea turtles, mostly large green
turtles, are imported annually into Bali from throughout Indonesia (Limpus 1997). In
1994, several thousand hawksbills, harvested from throughout Indonesia, were landed in
Bali (Limpus 1997).
Since 1956 in Irian Jaya, there has been a > 90% decline in nesting leatherback
turtles (Limpus 1994). Approximately 60% of the leatherback eggs laid on the world's
third largest leatherback nesting beach (north coast) were collected for local consumption
and sale (Starbird and Suarez 1994). In addition, approximately 200 leatherbacks are
currently harpooned off the southwest coast by local villagers for consumption (Suarez
and Starbird 1995). The annual harvest of green turtles in Papua New Guinea is
estimated between 10,000 and 20,000 animals (Limpus 1997). Apparently due to
overharvesting sea turtles are no longer found feeding offshore or nesting on beaches in
the vicinity of villages in Papua New Guinea (Spring 1982).
In 1953, over 1 million eggs were harvested from the Philippine Turtle Islands
(Parsons 1962). Kajihara (1974 cited in Polunin 1975) reported 5,000 adult hawksbill
and 50,000 large green turtles were captured annually in the Sulu Sea, and between 1961
and 1972, tortoiseshell from approximately 45,000 hawksbill were exported to Japan.
From 1951 to 1984, there has been a > 75% decline in green turtle egg production from
the Philippine Turtle Islands (Limpus 1994).
In Japan, between 1880 and 1890, 1,000 to 1,800 green turtles were harvested
yearly from Ogasawara Island and by the mid-1920s harvest rates had declined to fewer
than 250 animals. Since 1973, when the Japanese regained possession of the island,
harvest rates have been between 45 and 225 green turtles/yr (Horikoshi et al. 1994). In
addition, Japan has been the largest importer of sea turtle products in the world with
imports during the last 20 years representing over two million animals (Barr 1992).
In the 1920s at least two turtle processing factories operated on Northwest Islet
and one on Heron Island, Australia (Parsons 1962). During the 1924/1925 season,
approximately 1,600 green turtles were processed (Parsons 1962). During the 1928/1929
season so few nesting females were available on Heron Island that nesting animals on
nearby islands were harvested (Moorhouse 1933). For 40 years, prior to 1954, green
turtles were harvested on the Capricorn Reef, transported to Brisbane and shipped to
England (McNeill 1955 cited in Parsons 1962). On the west coast of Australia,
approximately 50 animals/wk were processed in a local turtle processing plant until 1951
(Caldwell 1951 cited in Parsons 1962). Although sea turtles are now protected in
Australia, indigenous people in Queensland and Western Australia are allowed to take
turtles for their own use (Limpus 1982). It is estimated that 10,000 green turtles are
harvested annually from the Torres Strait, of these approximately 4,000 are harvested by
Torres Strait Islanders and used locally, and the remainder are harvested by Papua New
Guineans and sold in their coastal markets (Daly 1990; Limpus 1982). Nearly 100% of
the eggs laid near indigenous communities are harvested (Limpus 1982).
Central Pacific Ocean Region
Coastal inhabitants throughout the Central Pacific Ocean have harvested marine
turtles for thousands of years. Marine turtle populations throughout the islands have
declined within historical times (Balazs 1982). In the Caroline Islands, the harvest of
marine turtle eggs is uncontrolled and occurs on all the islands in the group (McCoy
1982). Between 1985 and 1989, scutes from approximately 22,300 hawksbills were
exported to Japan from the Solomon Islands and Fiji (Daly 1990). Prior to mid-1994, an
estimated 2,000 hawksbills/yr were harvested from foraging grounds in Fiji (Limpus
Eastern Pacific Ocean Region
Mexico began the commercial exploitation of olive ridleys in 1961 (Marquez et
al. 1976; Cato et al. 1978). Both Mexico and Ecuador exported large quantities of olive
ridley and Pacific green turtle skins and leather to Japan, France, Spain, Italy and the
United States (Pritchard 1978; Mack et al. 1982; Milliken and Tokunaga 1987). From
1948 to 1956, approximately 60 tones of olive ridleys/yr were harvested and in the early
1960s, between 250 and 500 tones/yr were harvested. During the peak period of
exploitation, between 1965 and 1969, over 30,000 tones/yr of olive ridleys were
harvested (Marquez et al. 1976), representing approximately 700,000 animals (Marquez
unpubl. data cited in Cliffton et al. 1982). However, according to Carr (1972), the
Mexican government underestimated the total catch, he estimated more than a million
olive ridleys were harvested in 1968 alone. The harvest of olive ridleys had been so
intensive that at Piedra de Tlacoyunque, one of only four Pacific coast Mexican arribada
(Spanish for mass arrival of females on a nesting beach) nesting beaches, the aggregation
of turtles had been reduced from 30,000 to only a few hundred between 1968 and 1969
(Carr 1972; Pritchard 1979). By the early 1970s, three of the four Mexican olive ridley
arribada populations had been destroyed and the remaining location of mass nesting,
Playa Escobilla, Oaxaca, was being severely exploited (Carr 1967, 1979; Frazier 1981).
In 1977 and 1978, an estimated 70,000 and 58,000 olive ridleys were harvested
from Playa Escobilla, respectively (Cliffton et al. 1982). The decrease in size and
number of arribadas that occurred at Playa Escobilla indicated that the nesting
population was overharvested (Cliffton et al. 1982), however, the harvest continued.
From 1980 to 1985, the average annual harvest of olive ridleys was 32,343 (Hemrnandez
M. and Elizalde A. 1989 cited in Rose 1993). Harvest quotas were reduced from 48,944
in 1980 to 23,000/yr between 1986 to 1990 (Pefiaflores S. and Nataren E. cited in Rose
1993). In 1989, 2 to 12 boats illegally harvested 80 to 600 turtles/day in front of Playa
Escobilla (Blanco-Casillo 1990). In May 1990, Mexico declared a permanent ban on all
harvest and trade in sea turtles and their products (Aridjis 1990; Rose 1993).
At the turn of the century, an estimated 1,000 green turtles/mo were harvested
from Baja California and sent to San Diego, California (O'Donnell 1974). Green turtles
once nested along the coasts ofNayarit, Sinaloa; southern Sonora; and Baja California,
Mexico; however, today only the olive ridley nests in these areas (Felger and Cliffton
1977). The increase in human population and subsequent exploitation of nesting green
turtles are blamed for the disappearance of these northern Pacific Mexico nesting
populations (Felger and Cliffton 1977). As larger turtles became more scarce in the late
1960s, juvenile greens were harvested at a rate of approximately 250 to 360 turtles/day
(Cliffton et al. 1982). In the Gulf of California, for a three to four month period in the
winter of 1975, five turtle boats harvested an estimated 140 to 175 green turtles/wk as the
turtles lay dormant in the mud (Cliffiton et al. 1982). The number of turtles had declined
so drastically by 1975, Cliffton et al. (1982) reported that it took five boats of fishermen
with diving gear to capture as many turtles as one boat of Senri Indians with harpoons in
the 1960s. By 1977, Mexican fishermen had destroyed the population of dormant green
turtles in the Gulf of California (Felger and Cliffton 1977).
Green turtles also once nested along the southern Pacific coast of Mexico;
however, today only one major nesting site remains, Colola-Maruata Bay, Michoacan
(Cliffion et al. 1982). Nahuatl Indian informants reported there were 10 to 20 times more
nesting green turtles in 1970 than in 1979 (Cliffton et al. 1982). Over 4,500 metric tons
of green turtles were landed on the Pacific coast of Mexico (Mdrquez et al. 1976),
estimated to represent approximately 125,000 adult and subadults (Cliffton et al. 1982).
In the early 1970s, the Nahuatl Indians estimated they harvested 15,000 to 20,000
eggs/night at Maruata Bay and 70,000 eggs/night at Colola (Cliffton et al. 1982). In
1978, at least 10,500 green turtles were legally harvested from Michoacan and Jalisco (A.
Suarez pers. com. to Cliffton et al. 1982). In 1979, although a closed season had been
established, approximately 3,000 green turtles were illegally harvested (Cliffion et al.
In 1685, near Coiba Island, Panama, Dampier reported harpooning sea turtles
every day (Parsons 1962). Reports of abundant numbers of turtles continued in 1741 and
1794. By 1956, however, only a few turtles were reported (Parsons 1962). During the
1970s, marine turtle populations declined drastically (Cornelius 1982). From 1964 to
1976, over 96,000 kg of hawksbill shell, representing approximately 55,670 animals,
were officially exported from Panama (Vallester 1978 cited in Cornelius 1982).
In Ecuador, during the 1970s, at least six companies were involved in exporting
frozen sea turtle meat for human consumption and salted skin for the leather trade (Green
and Ortiz-Crespo 1982). From 1970 to 1978, up to 90,000 olive ridleys/yr were
processed and exported. For 1977 alone, Japan imported 66% and Italy imported 25% of
the skins exported from Ecuador (Green and Ortiz-Crespo 1982). The majority (72%) of
the meat was imported by the United States (Green and Ortiz-Crespo 1982).
In Peru, from 1965 to 1985, the mean annual turtle harvest was estimated at 1,222
1,636, and in 1987, it was estimated at > 22,200 animals (Aranda and Chandler 1989).
The harvest most likely represented a combination of greens, olive ridleys, and
leatherbacks, although the species harvested was not provided. The decrease in mesh size
of the nets used in the fishery from a 59 cm bar in 1979 (Hays Brown and Brown 1982)
to a 25 cm bar in the early 1990s (Vargas et al. 1994) could indicate a decrease in the
mean size of animals due to overharvest.
Eastern United States Region
At least four species of sea turtles were harvested along the east, Gulf of Mexico,
and west coasts of the United States. From 1880 to 1947, a minimum 1.5 million kg of
sea turtles or =z 10,700 animals (estimated number of animals based on R = 136.2
kg/green turtle (National Research Council 1990)), principally greens, were landed in
Florida (Ingle and Smith 1949; Rebel 1974). From 1950 to 1971, a minimum 509,500 kg
of green turtles or = 3,740 greens (estimated number of animals based on the same R =
136.2 kg/green turtle), and from 1951 to 1971, a minimum 66,535 kg of loggerheads and
Kemp's ridleys combined or from = 590 1,665 animals (estimated number of animals
based on 5 = 113 kg/loggerhead or 5 = 40 kg/Kemp's ridley (National Research Council
1990)), were landed in Florida (Rebel 1974). From 1890 to 1976, a minimum 4.3 million
kg of sea turtles (ranging from = 31,600 to 38,100 animals based on mean mass of green
or loggerhead turtles as described above) were landed at eight U.S. states and territories
(Witzell 1994). An estimated 11,000 turtles (loggerheads, Kemp's ridleys, and greens)
were unintentionally killed annually on the United States east coast and Gulf of Mexico
by shrimp trawlers (Henwood and Stuntz 1987). In the United States, indirect human-
induced mortality of loggerheads was estimated at 5,550 to 55,500 animals annually and
for Kemp's ridleys it was estimated at 555 to 5,550 animals annually. This mortality was
caused by shrimp trawls, discarded fishing gear and debris, other fisheries, dredging,
collisions with boats, oil-rig removal, and electric power plants (National Research
Gulf of Mexico Region
Up to the mid-1950s, as many as 2,000 nesting green turtles/yr were harvested
from the Yicatan Peninsula, Mexico and exported to the United States (Parsons 1962).
Between 1949 and 1969, > 3.6 million kg (R = 173,000 kg/yr) of green turtles and >
800,000 kg (R = 47,800 kg/yr) of loggerheads were harvested annually (Rebel 1974).
Annually, 200 kg of hawksbill shell was harvested from the Yicatan, no time period is
provided (Carranza 1967 cited in Rebel 1974). During the mid-1970s, the established
quotas for the east coast of Mexico ranged from 420 turtles to 2,000 turtles/yr, divided
evenly between greens and loggerheads (Cato et al. 1978). Populations of four of the five
species (hawksbill, loggerhead, green, and Kemp's ridley) of sea turtles that occur on the
east coast of Mexico have declined (Hildebrand 1982). The Kemp's ridley is the most
endangered of the seven species of sea turtles (Ross et al. 1989; Pritchard 1997). Decline
in the nesting population began prior to 1966 with high levels of egg exploitation
(Pritchard and Marquez 1973, Ross et al. 1989, Marquez 1994), and continues today due
to incidental capture by shrimp trawlers (Ross et al. 1989; National Research Council
1990; USFWS/NMFS 1992).
Greater Caribbean Region
In the greater Caribbean, sea turtles played an important role in the expansion and
dispersal of Europeans to the New World during the period of discovery, conquest, and
colonization (Carr 1954; Parsons 1962). Carr (1954) credited the green turtle as being the
single most important dietary factor that supported the opening up of the Caribbean to
European colonization. The green turtle provided ship crews with a source of fresh meat
and allowed for extended periods of travel (Carr 1954; Great Britain Colonial Office
Reports 1929 cited in Parsons 1962). Because of overexploitation, however, many
nesting and foraging populations throughout the greater Caribbean were depleted or
extirpated during early European expansion (Carr 1954; Parsons 1962, 1972; Dodd 1982;
Parsons (1962) suggests that commercial turtling in the west Atlantic probably
began in Bermuda, where at one time, there was a large assembly of nesting and foraging
green turtles (Ingle and Smith 1949; Parsons 1962). However, in spite of legislation
established in 1620 to protect sea turtles, within 150 years of English settlement sea turtle
populations around Bermuda were so reduced that a commercial harvest was no longer
profitable (Garman 1884b cited in Carr 1952; Parsons 1962). Carr (1954) suggests that
Bermuda was probably the first documented green turtle rookery to be extirpated. In
1671, Bahamian officials were asked to prepare legislation that would protect green
turtles against overexploitation, however, no action was taken (Great Britain Public
Record Office 1889 cited in Parsons 1962). By the 1700s, the Bahamian green turtle
population was also destroyed (Carr 1954; Dr. Archie Carr (interview) 1984).
The Cayman Islands were once known for the size of their green turtle rookery,
which supported the largest turtle fishery in the New World (Lewis 1940; Carr 1954;
Parsons 1962; King 1982). As early as 1503, Columbus recorded the massing of turtles
around the Cayman Islands (Carr 1954; Morison 1942 cited in Parsons 1962) and Long
(1774 cited in Lewis 1940) described how during the nesting season there were so many
turtles migrating towards the Cayman Islands that lost ships would navigate by the sound
of their swimming towards the Caymans. For almost 200 years, sailing ships from many
nations (e.g., British, Dutch, and French) arrived each summer to "turn turtle" (while on
the nesting beach female turtles are turned over on their backs to prohibit them from
returning to the water) (Parsons 1962). In 1684, it was reported that approximately 2,000
inhabitants of Port Royal, Jamaica, as well as, an unknown number of inland inhabitants,
fed daily on green turtle meat (Molesworth cited in Parsons 1962). By 1802, a little less
than 150 years after English settlement had begun, green turtle populations had become
so depleted that Cayman turtlers sailed first to the south coast of Cuba, then the Gulf of
Honduras, and finally to the Miskito coast of Nicaragua in search of ever dwindling
stocks of turtles (Lewis 1940; Carr 1954; Parsons 1962; King 1982).
Historical Harvest of Sea Turtles from Caribbean Waters ofNicaragua
Turtles have been harvested from Nicaragua's coastal waters and beaches for at
least the past 400 years (Carr 1954; Parsons 1962; Roberts 1965; Dampier 1968;
Nietschmann 1973; Mortimer 1981; Montenegro Jimdnez 1992; Lagueux 1993).
Unfortunately, no information is available on harvest rates prior to European arrival.
However, as early as 1633, the English had established a trading station at Cabo Gracias a
Dios (near the Honduras/Nicaragua border) (Parsons 1962). Parsons (1962) speculated
that the Miskitu Indians taught the English and their colonists how to turtle. By 1722,
Jamaican and possibly Cayman boats were annually visiting the Miskito Cays of
Nicaragua to catch and purchase green turtles and hawksbill shell from the Miskitu
Indians (Fernindez cited in Parsons 1962). However, turtling by the Cayman Islanders
off the coast of Nicaragua did not occur with any regularity until the early 1800s (Lewis
1940; Parsons 1962). Simmonds (cited in Parsons 1962) reported that by 1878, up to
15,000 turtles, although the species landed was not stated the majority were probably
green turtles, annually were landed in Europe, most of them having been caught by the
Cayman fleet which was known to harvest turtles in Nicaraguan waters.
During the first-half of the 20th century approximately 2,000 to 4,000 green
turtles were harvested annually from the Nicaragua coast by Cayman turtlers (Ingle and
Smith 1949; Parsons 1962). By the mid-1960s, after several hundred years of
exploitation, the Nicaraguan government no longer permitted Cayman Islanders to turtle
within their waters (Nietschmann 1973, 1976). Apparently, the Nicaraguan government
was not motivated by its concern for turtle conservation, but by its interest in securing a
constant supply of turtles for their newly established turtle processing plants (Rainey and
Pritchard 1972) and to decrease competition with other countries on the international
market. In late 1968, the first of three Nicaragua marine turtle packing plants began
processing green turtles for export (Nietschmann 1973, 1974). From 1966 to 1976,
Nicaragua exported 445,500 kg (equivalent to approximately 10,000 animals) of sea
turtle products into the United States alone during 7 of these 10 years (Cato et al. 1978).
From 1969 to 1976, up to 10,000 green turtles were harvested annually from the offshore
waters of Nicaragua for local and foreign consumption (Nietschmann 1972, 1973). By
1977, the processing plants were closed and Nicaragua became a signatory of CITES
(Hemley 1994). From 1985 to 1990, the sale of 16,700 green turtles was recorded in the
Puerto Cabezas, Nicaragua market (Montenegro Jimdnez 1992).
Hawksbills have been harvested from the offshore waters of Caribbean Nicaragua
and from the nesting beaches of the mainland and offshore cays for probably as long as
green turtles have been harvested from this region. Annual boat trips by the Miskitu
Indians to southern Nicaragua, Costa Rica, and to northern Panama to harvest hawksbills
is reported for as early as the 1600s (Parsons 1972; Nietschmann 1973). In the mid-18th
century, annual exports of tortoiseshell to Europe averaged 6,000 to 10,000 lbs (2,722 -
4,536 kgs) (Parsons 1956, 1972). The shell was traded by the Miskitus to the English for
cloth, guns, rum, and other goods (Parsons 1956, 1972; Nietschmann 1973). During a
12-mo period beginning in October 1968,41 hawksbills were harvested by one Miskitu
Indian village (Nietschmann 1972, 1973). For the first six months of 1969 compared to
the same time period in 1971 the harvest of hawksbills by one village increased almost
400%, from 27 to 107 animals (Nietschmann 1972, 1973). During the early 1970s,
approximately 1,000 to 1,200 hawksbills were harvested annually and exported to Japan
(Nietschmann 1981). Based on Japanese customs statistics, from 1970 to 1986,
Nicaragua exported 14,519 kg of tortoiseshell to Japan, representing approximately
13,000 hawksbills (Milliken and Tokunaga 1987). Although Nicaragua has been a
signatory of CITES since 1977 (Hemley 1994), approximately 20% of this trade occurred
post-1977 (Milliken and Tokunaga 1987).
Loggerhead and Leatherback Turtles
Very little is known about the loggerhead in Nicaraguan waters. Unconfirmed
reports indicate that loggerheads nest infrequently on Nicaragua's Caribbean coast (Carr
et al. 1982). Animals are captured incidentally in nets set for green turtles. Although
loggerhead meat is not eaten, throat and shoulder skin from loggerheads, as well as, green
and hawksbill turtles was exported to Europe (Nietschmann 1972, 1981; Bacon 1975).
Leatherback turtles are found in Nicaraguan waters and possibly nest in low numbers on
the mainland (Bacon 1975; Carr et al. 1982; this study). Prior to this study, nothing was
known about their capture from Nicaragua's Caribbean waters.
Marine Turtles and the Nicaragua Fishery
Today, the largest remaining foraging population of green turtles in the Atlantic
Ocean is located in coastal waters of eastern Nicaragua (Carr et al. 1978). The extended
continental shelf found in this region comprises cays, coral reefs, and extensive seagrass
beds. Green turtles use this area for foraging, developmental habitat, and as a migratory
pathway to the Tortuguero, Costa Rica nesting beach. Data from international tag
recoveries demonstrate that green turtles tagged in the Bahamas, Bermuda, Costa Rica,
Cuba, Florida, Grand Cayman, Mexico, Panama, and Venezuela have been captured in
Nicaragua's offshore waters (So6le 1994; Bjomdal and Bolten 1996; Bagley in litt.;
Bresette in litt.; Ehrhart pers. com.; Lagueux pers. obs.; Meylan in litt.; Moncada pers.
Marine turtles and their products no longer are legally exported from Nicaragua,
however, Miskitu and Rama Indians continue to conduct a legal marine turtle fishery for
local consumption centered on the green turtle. In 1965, the Nicaragua government
established a closed season to protect sea turtles in their Caribbean waters for several
months/yr, although turtles occur year around (Nietschmann 1972, 1973; Rebel 1974;
Weiss 1976; Bacon 1981; Peralta Williams 1991; Montenegro Jim6nez 1992; pers. obs.).
Because the law is not enforced, and some have argued, unenforceable (Nietschmann
1973; Peralta Williams 1991; D. Castro pers. com.), turtles continue to be harvested
during the closed season.
Hawksbill turtles are opportunistically captured by lobster divers, in nets set for
green turtles, and while nesting on mainland beaches or offshore cays. Juvenile and adult
hawksbills tagged in at least three countries (Costa Rica, Mexico, and the U.S. Virgin
Islands) throughout the greater Caribbean have been harvested in Nicaraguan waters
(Carr et al. 1966; Carr and Stancyk 1975; Bjomdal et al. 1985; Hillis 1994; Gardufio in
litt.; see Meylan 1997b for review). Green and hawksbill turtle meat are used for
subsistence and green turtle meat is sold in local markets. Hawksbill shell is sold to local
artisans who fashion various jewelry items that can be found for sale throughout the
Loggerhead and leatherback turtles are not targeted in the fishery, however, they
are also captured in nets set for green turtles. Two loggerheads, one tagged in Panama
(Meylan in litt.) and one in the Azores, Portugal (Bjomrndal in litt.) were recovered in
Nicaragua. Recently, there is a demand for loggerhead and green turtle meat as bait in
lobster traps and the hook and line fishery for shark. Almost nothing is known about
populations of loggerheads and leatherbacks in Caribbean waters of Nicaragua or their
use of this habitat.
The status of green, hawksbill, and possibly loggerhead populations in the greater
Caribbean, will depend, in part, on fishing activities of the Miskitu Indians. Offshore
waters of Caribbean Nicaragua are home to a large number of sea turtles representing
several species and nesting populations, as well as, the influx of animals from other areas
of developmental habitat throughout the greater Caribbean. Thus, the legal, unregulated
marine turtle fishery of Caribbean Nicaragua has the real possibility of severely
impacting marine turtle populations throughout the greater Caribbean and needs to be
To date, no attempt has been made to evaluate the impact of the Nicaragua marine
turtle fishery on turtle populations, although marine turtles have been harvested from
these waters for at least 400 years and the area supports the largest remaining green turtle
foraging population in the western Atlantic Ocean. Prior to the current study, only
cursory information about the fishery was available and nothing was known about its
current status. For these reasons, I focused my research on quantifying and describing 1)
human patterns and use of the marine turtle harvest and 2) biological parameters of the
animals harvested. From these data, I have conducted a preliminary evaluation of the
impact of this fishery on marine turtle populations in the region using absolute and
relative capture efforts and biological parameters of the harvested animals over time. The
evaluation of the fishery is based on data collected over a relatively short period of time
(in relation to generational time of the resource), however, these results provide base-line
information with which to compare subsequent years of harvest data. An evaluation of
the impact of the fishery is necessary to provide the basis for developing management
strategies to regulate the fishery.
This dissertation is organized into six chapters, including the current chapter. In
Chapter 2,1 describe and characterize the human patterns and use of the marine turtle
harvest, including a description of fishery participants, harvest locations, harvest methods
and their efficiency, and the human distribution of harvested animals. In Chapter 3, I
quantify the number of harvested animals by species, size, and sex for the majority of the
Caribbean coast of Nicaragua and analyze harvest rate and changes in size over time. In
Chapter 4, I describe the reproductive cycle and status of a subset of harvested green
turtles. In Chapter 5,1 conduct a preliminary evaluation on the impact of the fishery
based on historical information from the region, indices of current capture effort and
demographics of harvested animals over time, and results from the literature on
population modeling of long-lived organisms. In the final chapter, Chapter 6,1 make
recommendations for the development of a co-managed marine turtle fishery and provide
management recommendations for the fishery based only on biological constraints of the
species. Management options for the marine turtle fishery that can impinge on social,
economic, and cultural aspects of the turtlers, turtle butchers, and coastal inhabitants will
need to be discussed and agreed on among the turtlers, turtling-community
representatives, and regional and central government officials. I also provide
recommendations for future research.
HUMAN USE PATTERNS
Natural Resource Use
Throughout the world natural resources are harvested to meet dietary, medicinal,
cultural, religious, and financial human needs and wants (e.g., Robinson and Redford
1991, 1994; Jorgenson 1993; Rose 1993, 1996; Bodmer 1994; Bodmer et al. 1994;
Jenkins and Broad 1994; Bissonette and Drausman 1995; Jenkins 1995; Townsend 1995;
Vincent 1996; Freese 1997). As a result, many plant and animal populations have been
severely reduced or depleted. To mitigate negative impacts of human use or to aid in the
recovery of depleted populations, it is necessary to manage human resource use.
Effective resource management cannot occur without a knowledge of human use
patterns, such as, how and where resources are harvested, uses of the resources, and who
are the beneficiaries. It is also important to quantify harvest effort, yield, and distribution
of the harvest among resource consumers. These types of data can aid in the
development and implementation of management schemes that mitigate restrictions
imposed on resource users, meanwhile, improving compliance with regulations and the
probability of long-term resource availability. In addition, monitoring changes in human
use patterns, such as, harvest effort and rates, and areas of resource extraction, can
provide information about the sustainability of the harvest and the impacts of human use
on resource populations. Thus, the identification and quantification of human use
patterns are important for management schemes to be successful and can provide data
critical in monitoring population trends in a resource.
Human Use of Sea Turtles
Historical use of sea turtles by humans has been well documented in chronicles of
early travelers and by the scientific community because of strong interest in these animals
(Hornell 1927; Ingle and Smith 1949; Parsons 1962; Dampier 1968; O'Donnell 1974;
Frazier 1980; Bjorndal 1982). Marine turtles are exploited for their eggs, meat, shell,
skin, and other products. Although much of the literature is descriptive, a few studies
have quantified human use patterns of sea turtles, e.g., the use of olive ridley
(Lepidochelys olivacea) eggs in Honduras (Lagueux 1989, 1991) and green (Chelonia
mydas) and hawksbill (Eretmochelys imbricata) turtles in the Solomon Islands (Broderick
pers. com.), Seychelles (Mortimer 1984), and Nicaragua (Nietschmann 1972, 1973,
1979a; Weiss 1975, 1976).
Marine turtles on the Caribbean coast of Nicaragua have been harvested by
Amerindians since before the arrival of Europeans to the New World. These peoples,
now known as the Miskitu Indians, have long been recognized for their turtling skills
(Parsons 1962; Roberts 1965; Dampier 1968; Nietschmann 1972, 1973). Their turtle
harvesting methods were described in the early 1800s by Roberts (1965), in the mid-
1800s by Squier (1965) and Bell (1989) and in the early 1900s by Conzemius (1932).
Detailed accounts of natural resource use by two Miskitu turtling communities were
reported by Nietschmann (1972, 1973) and Weiss (1975, 1976).
Subsequent to the studies by Nietschmann (1972, 1973, 1979a) and Weiss (1975,
1976) in the late 1960s and early 1970s, there have been several major events in eastern
Nicaragua that have had a potential impact on human use patterns of marine turtles on
this coast. Between 1969 and 1977, three marine turtle slaughter houses opened and
closed; in 1977, Nicaragua became a signatory of the Convention of International Trade
in Endangered Species (CITES; Hemley 1994); and most recently, in 1990, the country
ended a 10-yr long civil war. As a result of these events, human use patterns described
by Nietschmann (1972, 1973, 1979a) and Weiss (1975, 1976) are probably no longer
indicative of current use patterns for the region. Their studies also lack a broader
perspective of Miskitu Indian turtling practices because they focused on resource use in
a single community.
The current Miskitu and Rama Indian marine turtle fishery is a legal, uncontrolled
harvest of green and hawksbill turtles. Although, in 1965, the Nicaragua government
established a closed season to protect green turtles in their Caribbean waters for several
months/yr (Nietschmann 1972, 1973; Rebel 1974; Weiss 1976; Bacon 1981; Peralta
Williams 1991; Montenegro Jim6nez 1992; pers. obs.) the closed season has been
ineffective. The duration of the closed season has, apparently changed from two months,
15 May to 15 July, in the 1970s (Nietschmann 1972, 1973; Rebel 1974; Weiss 1976;
Bacon 1981) to four months, 1 April to 31 July, in the 1980s and 1990s (Peralta Williams
1991; Montenegro Jimenez 1992 pers. obs). Although restrictions under the law are not
clear, the closed season has at different times varied in duration and included a total ban
against the harvest of turtles, a ban against the commercialization of marine turtles, and a
ban against the harvest of females (Nietschmann 1972, 1973; Weiss 1976; Montenegro
Jimdnez 1992). Several sources agree, however, that the law is not enforced, and some
have argued that it is unenforceable (Nietschmann 1973; Peralta Williams 1991; D.
Castro pers. com.). This is evident by the number of green turtles of both sexes landed
during the closed season months (see Chapters 2 and 3). In addition, in 1997,
enforcement of the closed season displaced the sale of green turtles from Puerto Cabezas
to the Rio Coco region of the country (D. Castro pers. com.), located on the border with
Honduras. Thus, in 1997, the result of the closed season was that green turtles were
distributed to non-traditional markets rather than reducing the harvest.
Human use patterns need to be determined to understand current impacts on turtle
populations, monitor changes in human use patterns, and to improve our ability to
successfully manage natural resource use. In this chapter, I characterize the following
aspects of the turtle fishery: who fishes for marine turtles, how and where turtles are
captured, and uses of marine turtles. In addition, I analyze the capture rate and human
distribution of harvested turtles on temporal and spatial scales. These data can be used as
a basis in the development of management recommendations for the marine turtle fishery.
These data are not only important in a current evaluation of the fishery but also for
establishing baseline levels with which future data can be compared. Identifying changes
in capture per unit effort also provides a means to indirectly monitor turtle population
trends and can be used as an indicator of overharvest and population decline.
Research was conducted on the Caribbean coast of Nicaragua (Figure 2.1).
Politically, the eastern one-third of the country, including the inhabited Corn Islands and
numerous offshore cays, is divided primarily into the Regi6n Aut6noma del Atlantico
Norte (RAAN) and the Regi6n Aut6noma del Atlntico Sur (RAAS). Three coastal
commercial centers are located in these regions: Puerto Cabezas in the RAAN, and
Bluefields and Corn Island in the RAAS. Outside these commercial centers people on the
coast reside in the following ethnically identified communities: Miskitu Indian, Miskitu
Indian/Creole mix, Carib, and Rama Indian. Creoles are a racial and cultural mixture of
African, European, and Amerindian traits (Hale and Gordon 1987). Caribs, or Garifunas
as they are also known, are of African and Amerindian descent. They arrived in
Nicaragua via Honduras as displaced slaves from the Caribbean island of St. Vincent
(Hale and Gordon 1987).
On the Caribbean coast of Nicaragua, turtlers are Miskitu Indians, Creoles, or
Rama Indians. In the RAAN, turtlers are Miskitu Indians. Most are bilingual, speaking
Miskitu and Spanish, and many of the older inhabitants are trilingual, also speaking
English. Miskitu is the language of everyday use in the RAAN and people identify
themselves ethnically as Miskitu.
Figure 2.1. Caribbean coastline of Nicaragua with coastal communities and towns.
840 830 82
5 Honduras Iralaya
Pahara_, Miskito Cays
Region Aut6noma Krukira-4-
140 del Atldntico Norte uerto Cabezas
......- ......... ...... S ea'
"130 Man O'War Cay a
y Sandy Bay irpyra Cay
Rio Grande Bar
,, wKings Cays
SetNe Pearl Cays
Regi6n Aut6noma .
del Atrantico Sur 0 Corn Islands
m .. -. -100 Fathom Contour Line
Rama Cay F c .. ......... Regional Boundary
| French Cay
Dept Rio San Juan "
Costa Rica I0
Tortuguero I kms
In the RAAS, the ethnic identity of the turtling communities is Miskitu Indian,
Miskitu Indian/Creole mix, or Rama Indian. In the Miskitu Indian/Creole mix
communities, inhabitants are from a Miskitu ancestry but many have assimilated a
Creole identity (Hale 1987; R. Carlos pers. com.). Creole English is spoken in the
Miskitu Indian/Creole mix communities, particularly among the younger inhabitants. In
one RAAS turtling community it was reported that many of the younger people no longer
speak Miskitu (R. Carlos pers. com.). Rama Indian communities are located south of
Bluefields. Residents from at least two of these communities harvest sea turtles.
The continental shelf of Nicaragua extends approximately 200 km at its widest
point eastward from Cabo Gracias a Dios (near the Honduras/Nicaragua border) to
approximately 20 km wide at its narrowest extension near the Costa Rican border. This
extensive shelf provides Nicaragua with a vast area of productive marine ecosystems
including mangrove and coral cays, underwater reefs, and seagrass pastures that supports
many commercially and locally valuable resources, such as, shrimp, lobster, scale fish,
and four species of marine turtles.
The marine turtle fishery occurs in Nicaragua's offshore Caribbean waters. The
main turtling area in the RAAN is located offshore approximately 48 to 80 km. The
Miskitu Indian/Creole mix communities located along the northern coast of the RAAS,
turtle in areas located approximately 16 to 24 km offshore. Rama Indian turtling areas
are located just offshore near French and Pigeon (located just north of French Cay) Cays.
In addition, turtles can be captured just offshore in the RAAN and RAAS as they migrate
to and from the nesting beach located at Tortuguero, Costa Rica (Figure 2.1).
Geographic and Temporal Distribution of Data Collection
In the RAAN, at the time of the study, five communities were known to fish for
green turtles. These were Awastara, Dakra, Krukira, Pahra, and Sandy Bay (Figure 2.1).
Beginning in April 1996 green turtles harvested by the community of Walpasiksa were
also landed at Puerto Cabezas. Data on the turtle harvest were recorded in the
communities of Awastara, Dakra, and Sandy Bay and when turtles were landed at the
commercial center of Puerto Cabezas. Data on the harvest of sea turtles by the
communities of Krukira, Pahra, and Walpasiksa were recorded only when turtles were
landed in Puerto Cabezas because there were insufficient funds and the residents of
Krukira were unwilling to participate in the study.
In the RAAS north of Bluefields, four communities were known to fish for green
turtles, at the time of the study. These were Rio Grande Bar, Sandy Bay Sirpi, Set Net,
and Tasbapaune (Figure 2.1). Along the southern coast of the RAAS, south of
Bluefields, at least two communities of Rama Indians also fish for turtles but were not
included in the study due to financial constraints. Data on the turtle harvest in the RAAS
were recorded in the four communities listed above. At the time of the study, no
additional Caribbean Nicaragua communities were known to fish for marine turtles.
I trained local community residents to collect the data. In addition, I conducted
informal interviews in communities and commercial centers during several short trips to
Nicaragua in April and May 1992, November and December 1995, December 1996, and
during a longer period of residence on the coast from November 1993 to February 1995.
Data on who participates in the turtle fishery, types of boats used, and methods used to
capture turtles were collected opportunistically. In the indigenous communities, my key
informants were community judges, secular and religious leaders, and turtlers; in
commercial centers they were the turtle butchers and employees of each municipality.
At each of the eight turtling communities and commercial center, one or two
residents of the site were employed as data collectors. Data collectors were selected
based on their: 1) acceptance in this role by community members, 2) interest and
availability in conducting the work, 3) ability to conduct the work, and 4) prior
experience in collecting and recording data. Three of the data collectors employed in this
study had worked previously with other researchers and had experience recording various
types of data. I trained each data collector and supervised data collection. When a turtle
boat arrived at any of the eight sites data collectors recorded the following: 1) turtlers
community of residence, 2) date, 3) number of days turtling, 4) capture method used, 5) if
nets were used, how many, 6) capture location, 7) number of animals of each species
captured, and 8) where captured turtles were consumed or sold.
The period for which data are available from each site varies and is not always
continuous (Table 2.1). Inconsistencies were due to the following factors: differing
initiation dates of data collection, insufficient funds to continue employment of
collectors, or unforseen circumstances (e.g. datasheets were stolen from the data collector
or damaged by rain). Depending on the site, the number of months for which data were
collected ranged from 29 mo for Awastara and Dakra to 64 mo in Sandy Bay Sirpi. The
percentage of months for which data were collected within the data collection period
ranged from 66.7% for Rio Grande Bar to 100% for Set Net (Table 2.1).
Table 2.1. Summary according to site of the time period during which data collection
occurred and the percent and number of months for which data were collected
on the landing of marine turtles on the Caribbean coast of Nicaragua.
Site of Data Time Period Percent of Months Data Collected
Collection (Duration of Period) (Number of Months)
Region Aut6noma del Athantico Norte
Awastara February 1994-April 1997 74.4
(39 months) (29)
Dakra February 1994-April 1997 74.4
(39 months) (29)
Puerto Cabezas b May 1991-April 1997 80.6
(72 months) (58)
Sandy Bay" May 1992-April 1997 83.3
(60 months) (50)
Region Aut6noma del Atlhntico Sur
Rio Grande Barc April 1991-December 1996 66.7
(69 months) (46)
Sandy Bay Sirpic January 1991-December 1996 88.9
(72 months) (64)
Set Net July 1994-December 1996 100
(30 months) (30)
Tasbapaune November 1993-December 94.7
1996 (38 months) (36)
Source of data for 1991: Cecil Clark, Puerto Cabezas, Nicaragua.
b Source of data for 1992 and 1993: Caribbean Conservation Corporation.
SSource of data for 1991-1993: Centro de Investigaciones y Documentaci6n de la Costa
Atldntica (CIDCA), Bluefields, Nicaragua.
Because the turtling grounds in the RAAN and RAAS are separated by
approximately 220 km of ocean, data were not combined for these two regions. Data
were analyzed either at the regional or community levels. Mean green turtle "Net
Capture Per Unit Effort" (N-CPUE) was calculated for each community and region. For
each trip, the N-CPUE was calculated using the following parameters: 1) "Days" =
number of days turtling, 2) "Nets" = number of nets used, 3) "Turtles" = number of green
turtles captured, and 4) "Net-Days" were calculated as "Nets" "Days"; thus N-CPUE =
"Turtles" "Net-Days". Informal interviews with turtlers, indicated that turtle nets are
approximately the same length, depth, and mesh size.
Tasbapaune was the only community that reported the capture of green turtles by
both entanglement nets and harpoons. Thus, data collected in Tasbapaune were used to
compare the relative effectiveness of nets and harpoons for capturing turtles. In order to
make this comparison, I devised a more general index of CPUE (G-CPUE) for each trip
using the following parameters: 1) "Days" = number of days turtling, 2) "Persons" =
number of turtlers, 3) "Person-Days" = "Persons" "Days"; thus G-CPUE = "Turtles" +
All statistical analyses were conducted using SAS software (SAS Institute, Inc.
1989). Univariate procedures were used to determine if distributions approximate
normality and a t-test was used to test for equality of variances. When assumptions for
parametric analyses were not met, non-parametric tests were used. Means 1 S.D. are
Turtlers and Living Conditions on the Turtlin&Grounds
Turtlers are male, usually older than 12 years of age, although younger boys can
accompany turtlers and assist in preparing food, tending the fire, cooking, cleaning, and
guarding the living quarters. Living conditions on the turtling grounds differ between the
RAAN and RAAS. In the RAAS, fishers (including men from all fishing activities
except for mechanized shrimp boats) have constructed semi-permanent structures on
several of the numerous coralline cays. In the RAAN, however, offshore cays are
covered with mangroves and are not habitable. In the RAAN, fishers eat and sleep on
their boats or spend the night in casitas (shelters constructed over shallow water from
mangrove poles, wood planks, palm thatch, and corrugated tin). On the boats, food is
cooked over wood fires contained in a metal kettle and fishers sleep on the floor.
Transportation and Capture Methods
In the RAAN, turtlers use wood-planked sail boats, referred to locally as "dories".
Dories are approximately 9 m long with a depth of 1 m from the gunwale to the boat floor
and approximately 1.8 m at the widest point. They are constructed from hand-sawn
planks of hardwood and powered by a main sail and jib. In the RAAS, turtlers that set
nets use boats powered by 10-15 hp outboard motors to reach the turtling grounds,
however, once they have arrived oars are used to set the nets and move between net-sets.
Outboard motor boats used for turtling are approximately 9 m long, 0.6 m deep, and 0.6
m wide between the gunwales at the widest point. Turtle harpooners use "cayucos",
which are dug-out canoes powered by sail and paddles. Cayucos are approximately 4 m
in length and 0.8 m deep.
In the RAAN, a fishing trip is usually focused on only one resource, however
lobster divers also capture turtles, and harvest conch opportunistically. In the RAAS, a
fishing trip is not resource specific. During a single trip the crew could set nets for
turtles, dive for lobster, set lobster pots, and fish for shark. It was not possible to
determine the number of active turtle boats per community in either the RAAN or RAAS
because boats can be 1) used to harvest different resources from week to week, 2) under
repair or construction, 3) rented out to a neighboring community, or 4) renamed once the
boat is repaired or repainted.
In both the RAAN and RAAS, green turtles are captured primarily with
entanglement nets. However, turtlers in Set Net and Tasbapaune (RAAS) continue to
strike turtles with harpoons. Entanglement nets are constructed from No. 18 nylon twine
and are from 21 to 27 m long and approximately 7.5 m deep, with a 40 to 47-cm bar mesh
size. Discarded flotation material found on the beach is strung on the headline and pieces
of coral, harvested from the reefs, are tied-in to the footline of the net to maintain it
vertical in the water column. A larger piece of coral is used as an anchor. Nets are set
during the day, over reefs or coral outcroppings, where green turtles are known to return
after having foraged on grassbeds throughout the day. At night, when an animal rises to
the surface to breath it entangles in the net. Rarely is more than one turtle captured in a
net at a time. Turtles rarely die in the nets because they are able to rise to the surface
while entangled in the net and breath throughout the night. In the early morning, nets and
any captured turtles are retrieved. Flippers are restrained by binding together each
anterior flipper with a posterior flipper with twine passed through a slit made in the distal
portion of each flipper. In the RAAN, animals are stored on their carapace (upside down)
in the bottom of the dory until the end of the trip. In the RAAS, animals are stored in
turtle crawls, or on their carapace on the cays for the duration of the fishing trip. Turtle
crawls are pens enclosed by mangrove poles set vertically in shallow water. Animals are
allowed to move freely within them.
Harpoons are constructed with a mahogany or palm wood shaft approximately 3
m in length. Inserted into one end of the shaft is a removable, triangular, 3-barbed point
approximately 5.5 cm in length made from a metal file. The point is attached to a rope
and at the other end of the rope is attached a wooden float. The shaft of the harpoon can
also be attached to the rope. Two-man crews, a "striker" and a "captain", search for
turtles early and late in the day. The striker poses on the bow of the boat ready to strike
any turtle that surfaces within their range, approximately 12 m (D. Castro pers. com.).
When a turtle is spotted the striker throws the harpoon, releasing the shaft and lodging the
point in the carapace causing the point to detach from the wooden shaft. The captain
quickly paddles the boat so that the striker can retrieve the float and shaft. The rope and
turtle are hauled into the boat.
Although green turtles are the focus of the turtle fishery other species are
sometimes captured. Hawksbill, loggerhead (Caretta caretta), and leatherback
(Dermochelys coriacea) turtles are captured incidentally in nets set for green turtles.
Hawksbills are also captured by harpoon, and by hand when diving for lobster.
Spatial and temporal comparison of entanglement nets
From December 1995 to December 1996, RAAS turtlers captured more than twice
as many green turtles/net-day as RAAN turtlers (R N-CPUE = 0.26 0.17 in the RAAS
and 0.12 + 0.08 in the RAAN; Wilcoxon rank-sums, P < 0.0001). The RAAS turtlers
spent fewer days turtling, used fewer nets, and captured more turtles/trip then RAAN
turtlers (Table 2.2). By community, the highest R N-CPUE in the RAAN (0.14 0.08 for
Sandy Bay) is similar to the lowest R N-CPUE in the RAAS (0.13 0.07 for Rio Grande
Bar) (Table 2.2).
Temporal change in mean monthly N-CPUE was analyzed for all sites combined
in the RAAN and RAAS separately, and for the community of Sandy Bay Sirpi, RAAS.
In the RAAN, mean monthly N-CPUE was calculated from December 1995 to April 1997
(17 mo) and in the RAAS, from December 1995 to December 1996 (13 mo). By region,
there was no correlation between mean N-CPUE and month, and neither slope was
significantly different from zero (RAAN, P = 0.36, r = 0.03; RAAS, P = 0.85, r = 0.06).
For Sandy Bay Sirpi, mean monthly N-CPUE was calculated from January 1991 to
December 1996 (data are available for 48 mo of the 72 mo period). There is a weak
correlation between mean N-CPUE and month, however, the slope is not significantly
different from zero (P = 0.22, r = 0.37).
Table 2.2. Comparison of green turtle, Chelonia mydas, capture effort using
entanglement nets by community and combined for the Regi6n Aut6noma del
Atlantico Norte (RAAN) and Regi6n Aut6noma del Atlantico Sur (RAAS),
Nicaragua from December 1995 to December 1996. Mean 1 S.D. is
followed by range and sample size. Means were calculated per trip.
Location Turtles Nets Turtling Net-Days" N-CPUEb
Rio Grande Bar
Sandy Bay Sirpi
'Net-Days / Trip = (Number of nets / Trip) (Number of days turtling / Trip).
'Net-Days / Trip = (Number of nets / Trip) (Number of days turtling / Trip).
b Net Capture per Unit Effort = (Number of turtles / Trip) / (Net-Days / Trip); mean green turtle N-CPUE is
significantly different between the RAAN and RAAS (Wilcoxon rank-sums, P < 0.0001).
Set Net and Tasbapaune are the only two communities where harpoons were
reportedly still in use. Between July 1994 and December 1996, Set Net reported the use
of harpoons for only two turtling trips, therefore data on the capture effort of turtles with
harpoons will be analyzed only for Tasbapaune. From December 1995 to December
1996 (13 mo), harpoons were used during 55 turtling trips. The mean G-CPUE was 2.7
0.9 (Table 2.3).
Table 2.3. Comparison of the efficiency of harpoons and entanglement nets as methods
for capturing green turtles, Chelonia mydas, by the community of Tasbapaune,
Nicaragua from December 1995 to December 1996. Mean + 1 S.D. is
followed by range and sample size. Means were calculated per trip.
Method Turtles Persons Days Turtling Person-Days" G-CPUEb
Harpoons 5.6 1.8 2.0 0.0 1.0 0.2 2.10.4 2.7 0.9
2-12 2-2 1-2 2-4 1.0-6.0
55 55 55 55 55
Nets 13.9 3.9 3.0 0.5 2.9 1.0 8.6 3.3 1.8 0.8
3-24 1-4 1-6 3-20 0.7-6
167 166 167 166 166
Person-Days / Trip = (Number of persons / Trip) (Number of days turtling / Trip).
b G-CPUE = (Turtles captured / Trip) / (Person-Days / Trip); mean green turtle G-CPUE is significantly
different between the use of harpoons and nets (ANOVA, P < 0.0001).
Harpoons and entanglement nets compared
Since Tasbapaune turtlers did not use harpoons and nets during the same turtling
trip, the effectiveness of netting and harpooning turtles can be compared statistically.
From December 1995 to December 1996 (13 mo), the G-CPUE was significantly higher
using harpoons (2.7 0.9) than nets (1.8 0.8; ANOVA, F1,219 = 60.7, P < 0.0001).
However, because netters spent nearly three times as many days turtling per trip than
harpooners they captured more than twice as many turtles per trip (Table 2.3).
Capture Locations: Regi6n Aut6noma del Atldntico Norte (RAAN)
Between May 1992 and April 1997 (60 mo), a total of 66 capture locations for
green turtles were recorded for the RAAN. Capture locations are places where turtlers
claim to capture turtles with either nets or harpoons. The approximate surface area of
capture locations range from 0.1 km2 to 6.5 km2. Hawksbills were captured at 23 of the
66 (34.8%) capture locations between December 1993 and April 1997 (41 mo), and
loggerheads at 27 of the 66 (40.9%) capture locations between September 1994 and April
1997 (32 mo).
A total of 41 green turtle capture locations were reported by turtlers from
Awastara, Dakra, Sandy Bay, and Puerto Cabezas for the same period (February 1994 to
January 1995, and December 1995 to April 1997, 29 mo). Hawksbills were captured at
20 (48.8%) and loggerheads at 25 (61.0%) of these 41 capture locations. The greatest
percentage of green turtles (40.5%, n = 4,702), hawksbills (26.9%, n = 21), and
loggerheads (39.9%, n = 252) were captured at Witties. An additional 27.6% (n = 174) of
loggerhead captures occurred at Leimarka. Each of the remaining capture locations
produced less than 11% of the turtles captured for the three species. Only trips with no
more than one capture location reported were included in these analyses. See Appendix
A for a detailed compilation of RAAN capture locations for each species.
The RAAN communities overlapped in their use of capture locations. Twenty-
one of 41 (51.2%) capture locations were used by more than 1 of the 6 communities
(including data collected from the communities of Krukira, Pahra, and Walpasiksa when
they landed their turtles at Puerto Cabezas) and 6 (14.6%) capture locations were used by
4 or 5 communities. None of the capture locations were used by all six communities. Of
the 19 (46.3%) capture locations used by only 1 community, 11 (26.8%) locations were
used exclusively by Sandy Bay, 6 (14.6%) exclusively by Awastara, 2 (4.9%) exclusively
by Dakra, and 1 location was used only by Walpasiksa (Appendix A).
Capture Locations: Regi6n Aut6noma del AtliAntico Sur (RAAS)
Between January 1991 and December 1996 (72 mo), a total of 77 capture
locations for green turtles were recorded for the RAAS. From August 1994 to December
1996 (29 mo), hawksbills were captured at 30 (39.0%) and loggerheads at 24 (31.2%) of
the 77 capture locations. However, a large proportion of animals for each species was
captured from a small proportion of the capture locations.
There was nearly complete partitioning of the turtling grounds between the four
RAAS communities. Turtlers from Rio Grande Bar and Sandy Bay Sirpi shared three
capture locations and turtlers from Set Net and Tasbapaune shared only one capture
location. Rio Grande Bar and Sandy Bay Sirpi did not share any capture locations with
Set Net or Tasbapaune. Because there was almost no overlap in the use of the 77 capture
locations among the RAAS turtling communities results for each community are
presented separately. See Appendix B for a detailed compilation of RAAS capture
location data for each community and species.
Rio Grande Bar. For 46 mo, between April 1991 and December 1996, 24 green
turtle capture locations were recorded. The majority of green turtles (53.8%, n = 3,027)
were captured at three locations (Half-way, Vietnam, and Karmutra Banks). The
remaining 21 capture locations each yielded less than 8% of the green turtles captured by
Rio Grande Bar turtlers. Hawksbills were captured at eight (33.3%) and loggerheads at
six (25.0%) of the 24 capture locations reported by Rio Grande Bar. Half-way Bank
yielded the greatest percentage of hawksbills (25.0%, n = 3), whereas, De Tronco yielded
the greatest percentage of loggerheads (40.0%, n = 4).
Sandy Bay Sirpi. For 64 mo, between January 1991 and December 1996, 34
green turtle capture locations were recorded. Three locations (Wainwin, South Schooner,
and Half-Way Bank) accounted for 34.6% (n = 1,709) of the green turtles captured. The
remaining 31 capture locations each yielded less than 8% of the green turtles captured by
Sandy Bay Sirpi turtlers. Hawksbills were captured at 9 (26.5%) and loggerheads at 8
(23.5%) of the 34 capture locations reported by Sandy Bay Sirpi. Three locations,
Hawksbill Bank, Halfway Bank, and Lousiksa accounted for 72.3% (n = 26) of the
hawksbills captured and two locations, Family Shoal and Diamond Spot, accounted for
64.3% (n = 18) of the loggerheads captured.
SetNeI. During the 30 mo period from July 1994 to December 1996, 7 green
turtle capture locations were recorded. One location, Fowlshit Bank, accounted for
64.2% (n = 488) of the green turtles captured. Hawksbills were captured at 5 (71.4%) and
loggerheads at 3 (42.9%) of the 7 capture locations. Long Reef accounted for 50.0% (n =
9) of the hawksbills captured and together with Fowlshit Bank accounted for 95% (n =
19) of the loggerheads captured.
Tasbapaune. For 36 mo, between November 1993 and December 1996, 14 green
turtle capture locations were recorded. Four locations (Haulover, Rivas, Buscan, and
Middle Banks) accounted for 71.6% (n = 4,392) of the green turtles captured. The
remaining 10 locations each yielded less than 9% of the green turtles captured by
Tasbapaune turtlers. Hawksbills were captured at 9 (64.3%) and loggerheads at 7
(50.0%) of the 14 capture locations. One location, Haulover Bank, accounted for 30.8%
(n = 20) of the hawksbills captured. The capture of loggerheads was more evenly
distributed, with 3 of the 7 capture locations each accounting for between 23% and 32.5%
of the total loggerhead captures.
Use and Human Distribution of Harvested Turtles
Green turtle meat is traditionally consumed by humans. It is either used for
subsistence by the turtlers, their families and friends, or sold in local and regional
markets. More recently, the meat is also used as bait in lobster pots and for shark fishing.
Turtles are transported to markets by the turtlers or purchased from the turtlers at sea or in
their communities and transported to other markets by the buyer.
Region Aut6noma del Atlntico Norte(RAAN). Green turtles were distributed
among at least 11 local and regional markets between November 1993 and April 1997 (42
mo). These markets are located as far north as Iralaya, Honduras and as far south as
Bluefields and Corn Island (Figure 2.1). The relative amounts of meat consumed within
and outside the turtlers community of residence differed between the three turtling
communities. For the period from February 1994 to January 1995, and from December
1995 to April 1997 (29 mo), for which monthly data collection occurred for all three
communities, Awastara turtlers sold the majority of their green turtles (85.2%) outside
their community of residence, whereas, the majority of turtles harvested by Sandy Bay
(84.1%) and Dakra (60.9%) were consumed in the turtlers community of residence (Table
2.4). Less than 5.5% of the turtles harvested by each community were consumed during
turtling trips (Table 2.4).
Of the green turtles sold to other markets, 82.0% (n = 5,895) were sold in the
commercial center of Puerto Cabezas. The remaining 18.0% (n = 1,291) were sold
among at least nine other markets (Table 2.4). A small amount of turtles sold by
Awastara (1.5%) and Dakra (2.1%) were sold to the turtling community of Sandy Bay.
Region Aut6noma del At"ntico Sur (RAAS). Green turtles were distributed
among at least 15 local markets between January 1991 and December 1996 (72 mo).
These markets are located between Sandy Bay Sirpi and Corn Island (Figure 2.1). For
the period from January to December 1996 (12 mo), for which monthly data collection
occurred for all four communities, Rio Grande Bar (89.0%), Sandy Bay Sirpi (60.5%),
and Set Net (61.1%) turtlers sold the majority of their green turtles outside their
community of residence. Tasbapaune, however, consumed the majority (71.5%) of the
Table 2.4. Number and (percent) of green turtles, Chelonia mydas, by location of
consumption for three Regi6n Aut6noma del Atldntico Norte (RAAN) turtling
communities from February 1994 to January 1995 and December 1995 to
April 1997 (29 mo). All markets are located within Nicaragua unless
RAAN TURTLING COMMUNITIES
Location of Consumption Awastara Dakra Sandy Bay Total
Community 774 1,022 3,351 5,147
(10.7) (60.9) (84.1) (39.9)
Bihmuna 0 63 5 68
(0) (3.8) (0.1) (0.5)
Bluefields 174 0 0 174
(2.4) (0) (0) (1.4)
Cabo Gracias a Dios 0 71 23 94
(0) (4.2) (0.6) (0.7)
Corn Island 382 20 15 417
(5.3) (1.2) (0.4) (3.2)
Iralaya, Honduras 0 41 2 43
(0) (2.4) (0.1) (0.3)
Koom 0 0 10 10
(0) (0) (0.3) (0.1)
Puerto Cabezas 5,215 364 316 5,895
(72.2) (21.7) (7.9) (45.7)
Rio Coco 0 0 8 8
(0) (0) (0.2) (0.1)
Sandy Bay 107 35 0 142
(1.5) (2.1) (0) (1.1)
Sold on caysa 202 0 48 250
(2.8) (0) (1.2) (1.9)
Unknown 72 13 0 85
(1.0) (0.8) (0) (0.7)
Turtling Trip 297 48 207 552
(4.1) (2.9) (5.2) (4.3)
Not Consumed (died) 3 0 0 3
(0.04) (0) (0) (0.02)
Total 7,226 1,677 3,985 12,888
a Sold to Colombian, Cuban, Honduran, and Nicaraguan commercial fishing boats for human consumption,
and lobster trap and shark bait.
turtles harvested by their turtlers. Less than 6.5% of the turtles harvested by each
community were consumed during turtling trips (Table 2.5).
Of the green turtles sold to other markets, 67.4% (n = 1,571) were sold in the
commercial center of Bluefields. The remaining 32.6% (n = 760) were sold among nine
other markets (Table 2.5). Rio Grande Bar sold 15.2% (n = 144) of the turtles it sold to
other markets to the turtling community of Sandy Bay Sirpi.
Temporal change in human distribution of harvestedurtes. The human
distribution of harvested green turtles was compared between years for five turtling
communities using a Chi-square test. Data were compared between 1994 and 1996 for
Awastara, Dakra, Sandy Bay, and Sandy Bay Sirpi; and between 1995 and 1996 for
Tasbapaune. There was a significant difference in the human distribution of harvested
green turtles from one year to the next for each turtling community (Chi-square test, P <
0.001, Table 2.6). From 1994 to 1996, for the three RAAN communities (Awastara,
Dakra, and Sandy Bay), there was an increase in the proportion of animals consumed in
the community, whereas, for the two RAAS communities (Sandy Bay Sirpi and
Tasbapaune) there was an increase in the proportion of animals sold outside the
community. For four of the five communities, the percent of green turtles consumed
during the turtling trip increased from 1994 to 1996, however, this category still
represents a small proportion ( 6.6%) of the fate of harvested green turtles (Table 2.6).
Hawksbills are harvested for their scutes. The meat can be consumed by the
turtler and his family, given to others for consumption, or discarded. From January 1991
Table 2.5. Number and (percent) of green turtles, Chelonia mydas, by location of
consumption for the Regi6n Aut6noma del Atldntico Sur (RAAS) turtling
communities from January 1996 to December 1996 (12 mo). All markets are
located within Nicaragua. RGB = Rio Grande Bar, SBS = Sandy Bay Sirpi,
SN = Set Net, TA = Tasbapaune.
RAAS TURTLING COMMUNITIES
Location of Consumption RGB SBS SN TA Total
Sandy Bay Sirpi
Sold on caysa
Not Consumed (died)
a Sold to Honduran and Nicaraguan commercial fishing boats.
Table 2.6. Human distribution of harvested green turtles, Chelonia mydas, compared
between years for five turtling communities. Percent of year's total is
followed by (number) of green turtles. Years within a community were
compared using a Chi-square test.
DISTRIBUTION OF HARVESTED GREEN TURTLES
Consumed in Sold Outside Consumed
Community Year Community Community on Trip P
1994 4.5(132) 94.7 (2,771) 0.8(23)
Awastara < 0.001
1996 14.5(440) 78.8 (2,385) 6.6(201)
1994 45.6(453) 53.6(532) 0.8(8)
Dakra < 0.001
1996 89.4(330) 4.9(18) 5.7(21)
1994 78.6 (1,279) 18.2(296) 3.3(53)
Sandy Bay < 0.001
1996 88.9(1,428) 4.8(77) 6.3(101)
Sandy Bay 1994 48.7(384) 51.3(404) 0(0) <0.001
San dy Bay --------------< 0.001
Sirpi 1996 37.1(418) 60.6(683) 2.3(26)
1995 79.9(127) 9.4(15) 10.7(17)
Tasbapaune < 0.001
1996 71.4 (1,759) 23.3(573) 5.3(130)
through 1996, at least 272 hawksbills were captured in the RAAN and RAAS (see
Chapter 3 and Appendix F). Although most captured hawksbills are killed, key
informants reported that sometimes scutes are removed from live animals by leaving
them in the hot sun, holding the carapace over a fire, or peeling off the scutes with the hot
blade of a knife. The live, scuteless animal is then released. Coastal inhabitants reported
seeing marked animals with regenerated scutes, however, the regeneration of scutes has
not been verified nor have mortality rates from this practice been quantified. Scutes are
dried and stored until a buyer is found. Local artisans make various types ofjewelry
from hawksbill shell which can be found for sale throughout the country including in
commercial centers along the coast, at the international and national airports, and at
tourist markets in Managua.
Loggerhead turtles are either released from the nets unconscious, killed and
discarded, or harvested for shark and lobster trap bait; the meat is not consumed because
of its strong flavor. Turtlers kill or club loggerheads unconscious to facilitate removal
from the nets, and to avoid the risk of being bitten. Mortality is high even among those
animals that are discarded while still alive because clubbed loggerheads are usually
discarded prior to regaining consciousness and most probably drown. From January 1994
through 1996 at least 825 loggerheads were reported captured (see Chapter 3 and
The capture methods described by Nietschmann (1972, 1973, 1974) and Weiss
(1975, 1976) are relatively unchanged except that outboard motors are now used by
RAAS net-turtlers, but not by harpoon-turtlers. Outboard motors are a relatively recent
addition and are a result of negotiations to end the civil war in the mid-1980s (D. Castro
pers. corn.). The RAAS fishers were provided with loans from the central government.
In the RAAN, however, turtlers continue to use sailing dories. Outboard motors are used
in the RAAS to travel between the mainland and turtling grounds, but not to aid in the
capture of turtles. Their use decreases travel time to and from the turtling grounds, but
because motors are not used to set or retrieve nets the use of outboard motors in the
RAAS does not account for the greater net capture rate.
Entanglement nets is the principal method in use today to capture turtles. Nets
were introduced to the Miskitu Indians by Cayman Island turtlers sometime before 1915
(Conzemius 1932). Prior to their introduction, Miskitu Indians used harpoons. Today,
only two of the Miskitu and Miskitu Indian/Creole mix communities (Tasbapaune and
Set Net) continue to use harpoons. In the late 1960s, the use of both nets and harpoons
by Tasbapaune turtlers was reported but no mention was made as to the relative
prevalence of either method (Nietschmann 1972, 1973). At least as early as 1971,
harpoons were no longer used by Sandy Bay Sirpi turtlers (Weiss 1975) and this pattern
The use of nets provides an advantage for neophyte turtlers, however, the
harvesting of coral to anchor-down the nets could be detrimental to the environment.
Because net-setters work in crews of 3 to 6 men, an inexperienced turtler has the
advantage of working with more experienced turtlers and will be successful at capturing
turtles and thus profit immediately. The opportunity to learn from more experienced
turtlers while sharing in the profits derived from their success could explain the
prominent use of nets today. One of the drawbacks to the use of nets is the indiscriminate
harvest of coral for use as weights on the footline and to anchor the net. Studies are
needed to quantify the amount of coral harvested and to evaluate the extent of damage to
Historically, harpoons were the sole method of capture, however, today, they are
seldom used. Their decreased use could reflect the need to be more skillful in order to be
successful. Harpooners probably spend more time practicing and need more patience to
become proficient, and the technique necessitates good communication and cooperation
between the striker and captain. Nevertheless, the increased investment in time needed to
be a proficient harpooner can be worthwhile in the long-run because harpoons are a more
efficient method of capturing turtles, at least during this study. However, Nietschmann
(1973) reported nets were more efficient, although the basis for this conclusion is not
On average, RAAN turtlers spend more days turtling and use more nets/trip but
capture fewer green turtles than turtlers in the RAAS. The difference between the regions
in the mean number of days spent turtling/trip is probably due to the distance of the
turtling grounds to the communities and the mode of travel. The RAAN turtlers travel
more than twice the distance than RAAS turtlers to reach most of their turtling grounds
and they travel by sail-powered dories compared to the use of motorboats by RAAS
turtlers. Because of the greater time invested by RAAN turtlers to reach the turtling
grounds it's not surprising that they spend more days turtling/trip.
The higher net capture rate of green turtles in the RAAS could reflect either
higher turtle density or better turtling skills by RAAS turtlers. Both regions of the
country, however, have been turtling for several hundred years, have been exposed to
similar outside influences and technology, and currently use the same netting technique.
Therefore the observed difference in capture rates is more likely explained by a difference
in green turtle abundance due to physiognomic and biotic habitat variation, turtle
migration patterns, or exploitation rates during the recent past. Mortimer (1981) found
that stomach contents of green turtles differed among several capture locations along the
Nicaragua coast suggesting that floristic composition varied among locations. Other
parameters, such as substrate type, current direction and flow rate, water depth and clarity
could also influence capture efficiency. In addition, storms can cause local perturbations
affecting habitat and subsequently sea turtle populations. Green turtles feed selectively
on young blades of turtle grass, Thalassia testudinum, thereby, decreasing the proportion
of lignin and increasing the proportion of protein consumed (Bjorndal 1980a). In 1988,
Hurricane Joan struck the coast of Nicaragua near Bluefields (Roth 1992). Although no
studies were conducted to identify changes that occurred to the offshore underwater
habitats in the RAAS as a result of the storm, its possible that the disturbance caused by
the hurricane stimulated new growth among the seagrass beds resulting in higher green
turtle population densities.
Secondly, funneling of turtles into a relatively narrow pathway as they migrate
south towards the nesting beach at Tortuguero, Costa Rica could increase turtle density
seasonally as turtles from the RAAN and farther north migrate south through the RAAS.
Turtles reportedly often use a longshore route when passing through Nicaraguan waters
during breeding migrations, traveling along the coast in nearshore waters (Carr 1954).
Therefore, in Nicaragua, when turtles use these longshore routes turtlers set their nets
over the shallow, mud flats, referred to as a "mudset", located within 3 km of shore
between Prinzapolka and Set Net point (see Figure 2.1, Carr 1954; Nietschmann 1973;
A third possibility is that exploitation levels in the two regions have differed
during the recent past, thus affecting current resource abundance. In the RAAN, during
the civil war, turtlers were only allowed to make trips to the offshore cays that originated
from Puerto Cabezas. For the period 1985 to 1990 (during the Sandinista/Contra war),
16,700 green turtles (R = 2,783 turtles/yr, S.D. = 681, range = 1,619 3,375, n = 6) were
harvested from the RAAN and landed in Puerto Cabezas (Montenegro Jimdnez 1992).
For the RAAS, harvest levels of marine turtles during the war are not available, however,
turtling activities were more severely decreased or suspended because of the large
military presence and battles fought near the communities. Thus, the higher capture rate
of turtles in the RAAS could be due to a higher density of turtles because of reduced
harvest pressure during the war compared to the RAAN.
Mean, monthly, N-CPUE in the RAAN, RAAS, and for Sandy Bay Sirpi does not
indicate, at this time, that the abundance of turtles within the size range of animals
harvested has declined during the study period. The trend in the N-CPUE for all three
analyses indicates there has been no change in the number of green turtles captured/net-
day. However, analyses were conducted over very short time periods (from 13 to 72 mo)
and could be too short to detect a change in the abundance of the foraging population. A
problem with using CPUE to estimate stock abundance is that fishers go where the fish or
turtles are and CPUE can remain high until the stock is seriously depleted, a situation
described as hyperstability by Hilbom and Walters (1992).
The N-CPUE for Sandy Bay Sirpi has increased 850% since the study conducted
by Weiss (1975) in 1972/1973, assuming net length, depth, and mesh size have remained
constant. Based on data provided by Weiss (1975), I calculated a mean of 0.02
turtles/net-day captured for Sandy Bay Sirpi turtlers for a one-year period beginning in
mid-1972 compared to a mean of 0.19 + 0.15 turtles/net-day calculated for the period
December 1995 to December 1996 (this study). The low N-CPUE realized in 1972/1973
could reflect declines in the turtle population resulting from the estimated 6,000 10,000
animals harvested annually from the coast between 1969 and 1973. Current harvest
levels for the coast are similar to those reported for the late 1960s and early 1970s.
Although this harvest level has not been continuous since the 1970s, Sandy Bay Sirpi
harvest levels have been relatively constant since at least 1991 (see Chapter 3). In 1990,
the country ended a decade-long civil war during which the exploitation of natural
resources by both nationals and foreigners was greatly reduced (Nietschmann 1995). The
harvest of turtles in the RAAS may not be as intense and the number of turtlers may have
decreased since the 1970s because today many men also fish for lobster and shark.
Whereas, in 1972, Weiss (1976) reported the only other major source of income in Sandy
Bay Sirpi was as temporary wage laborers on shrimp and fishing boats.
The 141 capture locations for marine turtles range in surface area from 0.1 km2 to
6.5 km2. Because of their vast size, each location has within it numerous sites where nets
are set. Marine turtle capture sites are dynamic, with new sites identified and known sites
abandoned due to low productivity. Turtlers identify potential new capture sites by
looking for submerged rocks on sunny, clear days. Nets are set and if turtles are captured
the site is given a name. According to the turtlers, each turtle uses several different
"sleeping rocks". Because sites within capture locations can be temporarily
unproductive, turtlers do not set their nets at the same site every day. Capture sites can
also become unproductive for long periods, e.g., in December 1995, P. Hills, a Rio
Grande Bar turtler, reported 13 unproductive capture sites. No information is available as
to how long a capture site can remain unproductive.
Partitioning of turtling grounds among the communities differs between the
RAAN and RAAS. In the RAAN, communities overlap extensively in their use of turtle
capture locations, whereas, in the RAAS, there is almost complete partitioning by the
communities. The lack of partitioning in the RAAN is probably because the distance to
the turtling grounds is approximately the same regardless from which community a trip
originates. Geographically, the RAAN communities are located relatively close to each
other but the turtling grounds are distant. In the RAAS, turtling grounds are located
offshore of each community decreasing the need to overlap on the turtling grounds or
travel farther than necessary. This partitioning of capture locations by community in the
RAAS was recognized as early as 1972 (Weiss 1975).
In the RAAN, managing the use of capture locations should be discussed at a
regional level with representation from each of the turtling communities. For example,
one of 35 capture locations in the RAAN (Witties) provided a large percentage of the
green (40.5%), hawksbill (26.9%), and loggerhead (39.9%) turtles captured. Therefore, if
reduction in the use of this one capture location could be agreed upon by all RAAN
turtlers a decrease in the capture rate of all three species could be realized.
The fact that some communities overlap in their use of capture locations could
facilitate enforcement. For example, compliance with regulations on the use of capture
locations could be enhanced by intercommunity surveillance. Because the proportion of
each community's harvest is not the same from each capture location, however, some
form of compensation might have to be devised so that any hardships can be more
equitably distributed among the communities.
In contrast, the establishment of regulations governing the use of capture locations
in the RAAS would best be approached on a community by community basis. Although
selection and agreement of regulations on the use of capture locations could be easier to
establish on a community by community basis, compliance and self-surveillance could be
more difficult to achieve. Since turtles are not confined in their movements by
community partitioning of capture locations, but probably move among the RAAS
capture locations and possibly between RAAN and RAAS foraging areas it will also be
important for the RAAS communities to develop a regional management plan, as well as,
inter-regional agreements for the use of this shared resource.
Human Distribution of Harvested Turtles
Approximately 50% of the green turtles captured are sold outside the turtlers
communities of residence, both in the RAAN (55.7%) and the RAAS (48.0%). The
percent of turtles distributed to outside markets varies greatly from one community to the
next, from a low of 10.8% for Sandy Bay to a high of 89.0% for Rio Grande Bar. The
decision to sell the harvest outside the community probably depends on the size of the
community, purchasing power of the community, and the turtlers need to obtain money.
Dakra, Sandy Bay, and Tasbapaune, communities with the largest number of
inhabitants, consumed more than 60% of the green turtles harvested by their turtlers. In
1994, the populations of Dakra and Sandy Bay were approximately 1,400 and 4,000
inhabitants, respectively (Comisi6n Nacional Interinstitucional 1995). In 1996,
Tasbapaune had approximately 3,200 inhabitants (R. Carlos pers. com.). In addition, the
capacity of Sandy Bay inhabitants to consume turtles was apparently greater than the
number of turtles harvested because they purchased 1.5% of Awastara's and 2.1% of
Dakra's turtle harvests.
The ability of a community to purchase turtles is dependent on the communities
overall purchasing power. The higher the median income in a community the more
money available to purchase goods and services, including turtle meat. Beginning in
1995, Sandy Bay and Dakra received assistance from private companies to enter into the
lobster trap fishery (D. Castro pers. com.). This has probably increased the median
income in each community. The increase in the percent of turtles consumed in Sandy
Bay and Dakra from 1994 to 1996 is possibly a result of this additional source of income.
Rio Grande Bar, Awastara, Set Net, and Sandy Bay Sirpi consumed the smallest
percent of their harvests in their communities, 9.1%, 10.7%, 32.7%, and 37.1%,
respectively. Of these communities, Rio Grande Bar and Set Net had the fewest
inhabitants, with approximately 150 and 200 inhabitants, respectively in 1996 (L.
Chumrnside pers. com.; F. Thomas pers. com.). In contrast, Awastara and Sandy Bay Sirpi
are large communities with approximately 1,200 inhabitants in 1994 (Comisi6n Nacional
Interinstitucional 1995) and 1,100 inhabitants in 1995 (E. Smith pers. com.), respectively.
Compared to Sandy Bay and Dakra, two other RAAN turtling communities, Awastara
has fewer sources of income and although they increased their community consumption
of turtle meat from 4.5% in 1994 to 14.5% in 1996 they still consume a relatively small
proportion of their turtle harvest.
The human distribution pattern of harvested turtles by Sandy Bay Sirpi is less
easily explained. Although Sandy Bay Sirpi is one of the largest of the turtling
communities it sold over 71% of its harvested turtles outside the community. However, it
also purchased 13.5% of Rio Grande Bar's turtles. For Sandy Bay Sirpi, the incentive to
sell a large majority of its green turtle harvest outside the community might be motivated
by a higher price/lb of meat sold in the Bluefields market compared to a lower price for
live turtles purchased from another turtling community. Turtle meat is sold in the
communities for approximately 1/3 to 1/2 the price/lb of meat sold in the commercial
centers (Lagueux unpubl. data).
The proportion of the harvest sold outside the turtlers community of residence
during this study is lower than the proportion sold to the turtle processing plants in the
early 1970s, for the two communities for which data are available. In 1971, Tasbapaune
sold 66% of its harvest to the plants (Nietschmann 1972, 1973) compared to 23.3% of the
harvest sold outside the community today. For a one-yr period, from 1972 to 1973,
Sandy Bay Sirpi sold 81.4% of its harvest to the plants (Weiss 1976) compared to 60.5%
of the harvest sold outside the community today.
These data probably underestimate the amount of trade occurring on the foraging
ground themselves. Because of the expanse of the area and the number of boats fishing
on Nicaragua's continental shelf there is a large potential for trade in sea turtles with
other boats. Informants report that on the cays, turtles are purchased to feed the crews of
fishing and lobster boats from San Andres Colombia, Cuba, Honduras, and Nicaragua,
and also purchased for transport to the Cayman Islands and San Andres Colombia to be
sold in their markets. More effort is needed to determine, for each species, the number of
animals purchased for bait, purchased by fishing boats for food, and transported to other
The patterns of human use of sea turtles in Nicaragua today are not much different
than during the past several hundred years of resource use on this coast. Since prior to
European contact, Miskitu Indians have harvested marine turtles from their coastal waters
for personal use, to trade for other goods, and to sell for income with which to purchase
other goods and services. Although the current harvest of marine turtles is no longer to
supply international markets, the local and regional (within Nicaragua) demand for a
source of inexpensive protein and tortoiseshell could be just as devastating to the marine
turtle foraging populations. As Frazier (1980) has noted, the issue is not whether the
exploitation of a resource is "good" or "bad" but whether or not the resource can sustain
harvest levels and patterns of resource use.
Data presented in this chapter are needed for the establishment of a management
plan for the Miskitu marine turtle fishery. These data are important to our understanding
of current human use patterns of marine turtles and are beneficial in making management
decisions. In addition, these data provide a basis with which to monitor changes in the
fishery which may result from management actions or due to external forces.
HARVEST RATES AND DEMOGRAPHICS OF MARINE TURTLES
Throughout history the harvest of sea turtles and their eggs have occurred
virtually wherever people and turtles coincide. Although the eggs of all species have
been harvested, animals of the seven species have been exploited to varying degrees.
Most harvests of marine turtles have targeted green turtles (Chelonia mydas) and
hawksbills (Eretmochelys imbricata) (Homell 1927; Ingle and Smith 1949; Carr 1954;
Parsons 1956, 1962, 1972; Hirth and Carr 1970; Nietschmann 1972, 1973; Rebel 1974;
Frazier 1975, 1979; Cato et al. 1978; Bjomdal 1982; Dodd 1982; King 1982; Milliken
and Tokunaga 1987; Mortimer 1984; Meylan 1997a). Harvests of the olive ridley
(Lepidochelys olivacea) (Carr 1967, 1972, 1979; Pritchard 1979; Frazier 1981), Kemp's
ridley (Lepidochelys kempi) (Pritchard and MArquez 1973), loggerhead (Caretta caretta)
(Brongersman 1982), and leatherback (Dermochelys coriacea) (Starbird and Suarez 1994;
Suarez and Starbird 1995) have either occurred for a shorter duration or have been more
localized. The endemic flatback turtle (Natator depressus) has played a limited role in
marine turtle harvests in Australia (Bustard 1972).
In Nicaragua, marine turtles have been harvested from beaches and offshore
waters of the Caribbean coast by indigenous coastal inhabitants and foreigners for over
400 years (Parsons 1962; Roberts 1965; Dampier 1968; Nietschmann 1973; Montenegro
Jimdnez 1992; Lagueux 1993). Four of the world's seven extant marine turtle species are
found offshore on Nicaragua's vast continental shelf-- greens, hawksbills, loggerheads,
and leatherbacks. Nicaragua's coastal area provides foraging and developmental habitat
for the largest green turtle foraging population in the Atlantic Ocean (Carr et al. 1978).
Juvenile and adult turtles immigrate to Nicaragua's coastal waters from throughout the
greater Caribbean. Green turtles also use these waters as a migratory pathway for travel
to and from the nesting beach at Tortuguero, Costa Rica (Carr 1954). Juvenile and adult
hawksbill turtles can be found foraging among offshore coral reefs and seagrass beds
(Nietschmann 1973, 1981; Lagueux pers. obs.). The hawksbill is the only species that
has been confirmed to nest on mainland beaches and offshore cays of Caribbean
Nicaragua (Nietschmann 1973, 1981). Almost nothing is known about the use of
Nicaragua's beaches and offshore waters by loggerheads and leatherbacks. Unconfirmed
reports, however, indicate that green, loggerhead, and leatherback turtles nest
infrequently on Nicaragua's mainland beaches (Bacon 1975; Carr et al. 1982; this study).
In the Nicaragua fishery, the green turtle is the principal species targeted.
Hawksbill turtles are harvested opportunistically whenever they are encountered.
Loggerhead and leatherback turtles, although not targeted in the marine turtle fishery, are
captured incidentally in nets set for green turtles.
Historically, only rough estimates have been made on the magnitude of the
Nicaragua marine turtle fishery (Lewis 1940; Ingle and Smith 1949; Carr 1954; Parsons
1962; Nietschmann 1973; Weiss 1975) and demographics of harvested animals have
never been reported. Because Nicaragua's marine turtle fishery is legal and not
clandestine, collecting data on the fishery and harvested animals is more easily
accomplished. Data on the number of animals captured by species, and size and sex of
harvested animals are needed to evaluate the impact of the fishery on marine turtle
populations that occur within Nicaraguan waters, as well as, the greater Caribbean region.
In addition, the sex ratio and size distribution of captured green turtles are probably
indicative of the foraging population because there is no evidence that net capture
methods are biased towards either sex or size, within the size range of animals captured in
the fishery. These data are also important in regulating and monitoring resource use.
In this chapter, I quantify the number of animals harvested by species per year and
describe the size and sex of harvested animals. The magnitude of the harvest for each
species is analyzed to determine seasonal and long-term trends. The size and sex ratio of
harvested animals by species are determined to provide baseline information on the
segment of each population impacted by the fishery, and to compare the demographics of
harvested green turtles between regions of the coast. The size distribution of harvested
female green turtles is compared to the size distribution of nesting females to determine
the proportion of harvested animals that are smaller than reproductive size. A temporal
analysis is conducted to determine if changes have occurred in the mean size of harvested
The turtling communities and commercial center where data were collected are
described in Chapter 2. The initiation date for the collection of harvest data on each turtle
species differed. Partial data on the harvest of green turtles from both the Regi6n
Aut6noma del Atlantico Norte (RAAN) and the Regi6n Aut6noma del Atlantico Sur
(RAAS) have been available at least since 1991 and are included in this study. Data
collection on the harvest of hawksbills was initiated January 1991 in the RAAS and
December 1993 in the RAAN. Data collection on the capture of loggerheads and
leatherbacks was initiated January 1994 in the RAAS and September 1994 in the RAAN.
For all species, data collected through April 1997 in the RAAN and December 1996 in
the RAAS are included.
In 1991, Cecil Clark, head of the marine turtle butchers cooperative recorded
landings of turtles at Puerto Cabezas. From 1991 to 1993, the collection of harvest data
in the communities of Rio Grande Bar and Sandy Bay Sirpi was conducted by the Centro
de Investigaciones y Documentaci6n de la Costa AtlAntica (CIDCA). Beginning in April
1992 in the RAAN and in November 1993 in the RAAS, I trained local data collectors.
Supervision of data collection has been conducted by Denis Castro, my Miskitu Indian
counterpart, and me. Selection and employment of data collectors are described in
Types of Harvest Data Collected
Harvest and demographic data on marine turtles were recorded when a boat
returned from a turtling trip. For each turtling trip, the following data were recorded: 1)
turtlers community of residence, 2) date trip terminated, and 3) total number of turtles of
each species captured. For as many individual turtles as possible, the following data were
also recorded: 1) species, 2) plastron length (PL), and 3) sex. Plastron length was
measured along the midline from the anterior junction of the skin and intergular scute to
the posterior termination of the plastron midline with a 150-cm flexible tape measure.
Although plastron length is not the preferred measurement taken among sea turtle
biologists it was the most practical because animals are transported and stored upside
down. Sex was based on the examination of external sex characteristics, i.e., tail length
and the size and shape of the anterior flipper claws.
During a preliminary study conducted from May 1992 to March 1993 in Puerto
Cabezas and from May 1992 to December 1993 in Sandy Bay, the following turtle
measurements were recorded: 1) minimum (notch-to-notch) curved carapace length
(CLN), 2) minimum (notch-to-notch) straight carapace length (SLN), 3) body mass (WT),
and 4) sex. A 150-cm flexible tape measure was used for all curved measurements and a
127-cm tree caliper was used for all straight measurements. Minimum carapace lengths
were measured along the midline from the anterior edge of the nuchal scute to the
posterior termination of the midline to the nearest 0.1 cm. Body mass was determined to
the nearest 2.5 lb with a 500-lb spring scale and converted to kilograms.
Calculation of Harvest Rates
The annual harvest rates of marine turtles are minimum estimates because harvest
data were not collected from every Miskitu Indian and Miskitu/Creole turtling
community nor from any of the Rama Indian communities (see Chapter 2). In addition,
not all turtles captured were necessarily reported to the data collectors and none of the
turtles captured incidental to other fisheries were reported. Monthly harvest rates for
each data collection site were calculated based on the numbers of turtles actually recorded
and estimated to have been landed. For a variety of reasons, however, data were not
collected during every month of the study period at all data collection sites (see Methods
in Chapter 2). For those months for which data were not available, I estimated the
monthly harvest rate based on known monthly harvest rates for each site, for each year.
In 1995, data were collected for only two to three months in Awastara, Dakra, and Sandy
Bay. Thus, I estimated the monthly harvest rates for each data collection site based on 12
months of known harvest rates, 6 months prior and 6 months post the period of missing
Care was taken not to include the same harvested animal more than once in the
totals. Because, in the RAAN, turtle boats dock at more than one data collection site it
was possible for animals to be recorded twice. To avoid overestimating the harvest rate, I
excluded from the total, animals recorded at one site but sent to another site in which a
data collector was employed. However, if turtles were sent to a site where no data
collector was employed then these animals were included in the total.
A series of 11 body measurements were used to attempt to characterize
morphological differences between male and female turtles foraging in Nicaragua.
Because sea turtle biologists record any of eight different carapace lengths (Pritchard et
al. 1983), it is difficult to make comparisons among studies. Therefore, regression
equations were developed to predict the other measurements from minimum curved
carapace (CLN). For green turtles, measurements were taken from a stratified random
sample of animals landed at Puerto Cabezas between November 1993 and January 1995.
Each month I attempted to measure a minimum of 40 harvested animals, 10 from each of
the following four categories: "small" males, "large" males, "small" females, and "large"
females. The cut-off between "small" and "large" was based on the size of the smallest
nesting females at Tortuguero, Costa Rica in 1988 (Caribbean Conservation Corporation
unpubl. data). Animals smaller than 89.8 cm minimum straight carapace length were
categorized as "small". The sex of animals was verified when they were butchered (see
Chapter 4). All hawksbills were measured whenever possible. No loggerheads or
leatherbacks were measured because they are not landed at Puerto Cabezas. Any
measurement that might have been affected by deformities or mutilations were excluded
from the analyses.
The 11 body measurements I recorded were the following: 1) minimum (notch-
to-notch) curved carapace length (CLN), 2) minimum (notch-to-notch) straight carapace
length (SLN), 3) maximum (tip-to-tip) curved carapace length (CLT), 4) maximum (tip-
to-tip) straight carapace length (SLT), 5) plastron length (PL), 6) plastron to vent length
(VENT), 7) tail length (TAIL), 8) length of each anterior flipper claw (CLEN), 9)
minimum basal diameter of each anterior flipper claw, 10) maximum basal diameter of
each anterior flipper claw, and 11) body mass (WT). Maximum carapace lengths were
measured from the most anterior to the most posterior projections of the carapace. Vent
and tail lengths were measured from the posterior termination of the plastron midline to
the center of the vent (VENT) and to the tip of the straightened tail (TAIL). Length of
each anterior flipper claw was measured from the junction of the skin and claw to the tip
of the claw along the outer curvature and the mean CLEN/turtle (RCLEN) was calculated
from right and left measurements. Minimum and maximum basal diameters of each
anterior flipper claw were measured with a dial caliper to the nearest 0.05 mm and used to
calculate the basal area of each anterior flipper claw. Basal area was calculated using the
formula for the area of an ellipsoid:
A = iab
where it is 3.14, a is one-half the shortest diameter, and b is one-half the longest
diameter. Mean basal area of anterior claw/turtle (RCBASE) was calculated from right
and left measurements. All other measurement are as previously described (see Types of
Harvested Data Collected in Methods). A 127-cm tree caliper was used for straight
carapace measurements. Unless otherwise stated, measurements were made with a 150-
cm flexible tape measure.
Accuracy of Sex Identification of Green Turtles
The ability of the Puerto Cabezas data collector to sex animals based on external
characteristics was evaluated to determine the accuracy of the data obtained. He first
sexed each animal externally, and I noted whether or not external sex characteristics were
obvious (as described above). Sex was then verified based on gonadal examination of the
butchered animals. Turtles were grouped into 2.5-cm size classes based on plastron
length in order to identify the minimum plastron length at which an animal can be sexed
using external characteristics.
Size and Life Stage Distribution of Harvested Green Turtles
Two data sets were analyzed to identify the life stage of green turtles impacted in
the fishery. One data set is from the harvested animals landed at Puerto Cabezas during
the preliminary study between May 1992 and March 1993. Only female carapace lengths
recorded during the preliminary study were compared to nesting females at Tortuguero,
Costa Rica. Data from the preliminary study were used because the data collectors ability
to accurately sex animals based on external characteristics was found to be highly reliable
(see Results on Sex ratio of harvested green turtles). The second data set is from the
harvested animals measured and sexed between February 1994 and December 1996 at
eight data collection sites where turtles were landed.
Using the preliminary data set, minimum straight carapace lengths (SLN) of
harvested female green turtles landed at Puerto Cabezas, Nicaragua were compared to the
maximum straight carapace lengths (SLT) of reproductively mature females measured on
the nesting beach at Tortuguero, Costa Rica (Caribbean Conservation Corporation unpubl
data). Predicted SLN measurements were calculated from measured SLT of Tortuguero
turtles. A regression equation to predict SLN was calculated from carapace lengths of
animals I measured in Puerto Cabezas (see Methods on Turtle Morphometrics).
Using data collected at eight sites, the number of harvested male and female green
turtles that were reproductively immature and mature were estimated for the RAAN and
RAAS because smaller animals cannot be reliably sexed based on external characteristics
(see Results on Sex ratio of harvested green turtles). For males, reproductive maturity
was based on the presence of sperm, although this does not indicate that animals have
reproduced (see Chapter 4). For females, reproductive maturity was based on the
presence of corpora lutea in the ovaries (see Chapter 4) and the minimum size of females
at the Tortuguero, Costa Rica rookery. Minimum plastron lengths of "mature" males and
females were used as a cut-off between mature and immature animals. Estimates for the
number of harvested males and females of reproductively immature and mature status
were calculated by multiplying the number of harvested animals that were below and
above the cut-off sizes for each sex by the proportion of harvested animals of each sex
calculated for each region (see Results on Sex ratio of harvested green turtles).
Seasonal and temporal harvest trends
Pearson correlation coefficient was used to determine if there was a relationship
between the monthly number of green turtles harvested in the RAAN and monthly
rainfall recorded at Puerto Cabezas. Daily rainfall was recorded by either an assistant or
Analysis of variance was used to compare the RAAN mean monthly harvest rate
of green turtles during this study with the mean monthly harvest rate calculated by
Montenegro Jimenez (1992) from 1985 to 1990. Although data from Montenegro
Jimenez (1992) were collected from landings of turtles only at Puerto Cabezas, her data
represent the total harvest of animals in the RAAN at that time because fishing activities
were restricted during the Nicaragua civil-war. For the RAAS, time series analysis was
used to examine the trend in the monthly harvest of green turtles. Time series analysis
also was used to examine the trend in the monthly recorded harvest of hawksbills and
capture of loggerheads for all data collection sites combined. Trend data were examined
for the possibility of autocorrelated residuals. A regression model with autoregressive
errors was used when autocorrelation among error terms was significant at P 0.05;
however, when they were not, a simple linear regression model was used.
Pearson correlation coefficient was used to determine the relationship between
body measurements and carapace length. Analysis of covariance was used to determine
if males and females differed in their relationship between CLN and other body
measurements. Dependent variables were log transformed when the assumptions of
regression analysis were not met. Regression equations are reported separately when
intercepts and slopes were significantly different between males and females, otherwise
data were pooled and regression equations were recalculated.
Evaluating sex ratios
McNemar's test of dependent samples was used to analyze the accuracy of the
Puerto Cabezas data collector to determine sex of animals based on external
characteristics (Zar 1996). A Chi-square test was used to determine if the sex ratio of
harvested green turtles in the RAAN and RAAS differed. A normal approximation to a
binomial distribution (One-sample Proportion test) was used to determine if the sex ratio
of harvested animals differed from a one-to-one ratio.
All statistical analyses were conducted using SAS software (SAS Institute, Inc.
1989). Univariate procedures were used to determine if distributions approximate
normality and a t-test was used to test for equality of variances. When assumptions for
parametric analyses were not met, non-parametric tests were used. Means 1 S.D. are
From 1991 to 1993, the estimated annual harvest ranged from 6,169 to 9,440
green turtles based on extrapolations of data collected at three or four sites, depending on
the year (Figure 3.1). From 1994 to 1995, the estimated annual harvest ranged between
9,413 to 11,077 green turtles based on extrapolations of data collected at eight collection
sites. In 1996, the minimum annual harvest was 10,166 green turtles based on
12000 1 3 ESTIMATED
(n = 8)
(n =4) (n = 8)
8000 (n 4)
1991 1992 1993 1994 1995 1996
Figure 3.1. Minimum (i.e., recorded) and estimated (i.e., extrapolated) annual harvest of green turtles, Chelonia
mydas, landed on the Caribbean coast of Nicaragua per year from 1991 to 1996. Sample size for
each year refers to the number of sites where data were collected. See text for an explanation of how
estimated data were calculated and see AppendixC for a list of sites represented in each year. Data
were, in part, provided by C. Clark for 1991, Centro de Investigaciones y Documentaci6n de la
Costa Atlintica for 1991-1993, and Caribbean Conservation Corporation for 1992-1993.
data recorded at the same eight sites (Figure 3.1). Detailed harvest levels for each
community are compiled in Appendix C.
Seasonal and temporal trends of harvest levels
Mean monthly rainfall from April 1994 to May 1995 was 221.6 mm 176.1
(range = 13.7 547.0 mm, n = 14). There was no correlation between monthly rainfall
recorded in Puerto Cabezas and the number of green turtles harvested in the RAAN (P =
0.87, r = 0.05).
In the RAAN, from 1985 to 1990 (during the Sandinista/Contra war), 16,700
green turtles (R = 245.6 turtles/mo 18.8, range = 0 739 turtles/mo, n = 68) were
reported harvested (Montenegro Jimdnez 1992). From February 1994 to January 1995
and from December 1995 to April 1997 (post Sandinista/Contra war), 14,017 green
turtles (R = 483.3 turtles/mo 142.7, range = 131 745 turtles/mo, n = 29) were
harvested in the RAAN (Figure 3.2). There was a significant increase in the number of
green turtles harvested/mo from the Sandinista/Contra war to the post-war period
(ANOVA, F,95 = 49.98, P < 0.0001).
In the RAAS, from August 1994 to December 1996, 10,019 green turtles (R =
345.5 turtles/mo 171.8, range = 47- 718 turtles/mo, n = 29) were harvested by four
communities. Although the harvest rate has not changed significantly (P = 0.29, based on
a regression model of autoregressive errors) there has been an increase of 58.7 turtles/yr
during this 2.5-yr period (Y = 269.2 + 4.9X, where X is the number of months elapsed;
Figure 3.3). Data for one RAAS community, Sandy Bay Sirpi, were available for a six-yr
period which allowed the evaluation of harvest trends for a longer time period. From
W 200 I
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997
Figure 3.2. Number of green turtles, Chelonia mydas, harvested in the Regi6n Aut6noma del Athintico Norte
(RAAN), Nicaragua from January 1985 to April 1997 (149 mo). No data are available
for months that appear as zeros. There was a significant increase in the mean number of turtles
harvested/mo between the periods 1985 1990 and February 1994 April 1997 (ANOVA, F1,95
49.98, P < 0.0001). Data for 1985 to 1990 taken from Montenegro Jimenez (1992).
0.., n o r.].
.:.- 0..:.- d _-
Number of green turtles, Chelonia mydas, reported harvested in the Regi6n Aut6noma del
AtlAintico Sur (RAAS), Nicaragua from August 1994 to December 1996 (29 months).
There was no significant change in the number of turtles harvested/mo. The line is based
on a least squares regression (turtles/mo = 269.2 + 4.9X, where X is the number of months
elapsed; P = 0.29).
January 1991 to December 1996 (72-mo period), 5,036 green turtles (5 = 85.4 turtles/mo
52.3, range = 3 237 turtles/mo, n = 59) were harvested. Based on a simple regression
model the harvest rate of green turtles by Sandy Bay Sirpi turtlers has remained
essentially constant at a decrease of 1.1 turtles/yr (P = 0.78) during this 6-yr period
Morphometric parameters of harvested turtles
A total of 634 turtles were measured. For animals where sex was confirmed by
dissection, minimum (notch-to-notch) curved carapace lengths (CLN) for females ranged
from 75.0 113.2 cm (n = 276) and for males it ranged from 72.2 108.6 cm CLN (n =
282). Pearson correlation coefficients are high (r > 0.89) among the various carapace
lengths (i.e., CLN, minimum straight carapace (SLN), maximum curved carapace (CLT),
maximum straight carapace (SLT)); plastron (PL); and body mass (WT) for sexes
combined or separate. Correlation coefficients for each of plastron-to-vent length
(VENT), tail length (TAIL), and mean claw basal area (xCBASE); regressed with each of
CLN, SLN, CLT, SLT, PL, and WT are higher when sexes are separated (r > 0.69) than
when sexes are combined (r < 0.52). Mean claw length (xCLEN) is more highly
correlated with all but one (PL, r = 0.66) of the other eight body measurements for males
(r > 0.73) than for females (r < 0.67). Between 23% and 55% more of the variation in
xCLEN of males than females can be attributed to other body measurements.
Coefficients are high among measurements of sexually dimorphic external characters
(RCBASE:VENT or TAIL) for males and sexes combined (r 0.92) and lower for
females (r = between 0.72 and 0.76). Plastron and VENT are highly correlated with
41..IP..AHHHI Il f.3 .f .l.f.j.JgfljJ.*.l.
1991 1992 1993 1994 1995 1996
Figure 3.4. Number of green turtles, Chelonia mydas, reported harvested at Sandy Bay Sirpi, Nicaragua
from January 1991 to December 1996 (72 months). There was no significant change in the
number of turtles harvested/mo. The line is based on a least squares regression (turtles/mo =
89.0 0.092X, where X is the number of months elapsed; P = 0.78). No data are available
for months that appear as zeros. Data for 1991 1993 provided by Centro de Investigaciones
y Documentaci6n de la Costa AtlAntica.
X- x m x ---- .7 r .- ...%IA
TAIL for sexes combined or separate (r > 0.97). Correlation coefficients for all ten body
measurements are shown in Appendix D.
There was no significant difference between males and females for the
relationship between CLN and each of SLT, log PL, and log WT; therefore, data were
pooled. There was, however, a significant difference between males and females for the
relationship between CLN and each of CLT, SLN, log VENT, log TAIL, log RCBASE,
and log RCLEN; therefore, regression equations were calculated separately by sex.
Although analysis of covariance showed a significant difference between males and
females for CLN:CLT and CLN:SLN, there is no apparent sexual dimorphism as
indicated by the very high coefficients for the sexes combined and separate (r = 0.99 for
both). Regression equations and statistical results are summarized in Appendix E.
Scatter plots of the 10 body measurements (each plotted against the other for a
total of 45 pairs) were visually evaluated to determine if any pairs of measurements
provide a means to distinguish between males and females. For 24 of the 45 pairs of
measurements, divergence between males and females is obvious. However, not all pairs
were equally divergent, nor was there complete divergence between males and females
for any pair, particularly among the smaller sizes of animals. The greatest divergence
between the sexes was observed in the plot of TAIL:WT, although TAIL plotted with
CLN, SLN, CLT, SLT, PL (body lengths) were also highly divergent. Using the plot of
TAIL:WT measurements, I developed a key to distinguish between males and females
(Table 3.1). Although TAIL and WT were more easily distinguished on the scatterplot
Table 3.1. Keys to distinguish between male and female green turtles, Chelonia mydas,
using tail length with either body mass or minimum curved carapace length
(CLN). Scatterplots of tail length with body mass, and tail length with
carapace length were used to distinguish between the sexes. For some
measurements, however, sexes were indistinguishable (IND). Keys are based
on confirmed males (n = 278) and females (n = 275). Cut-off measurements
to distinguish between the sexes are approximate. Tail length = distance from
posterior termination of the plastron midline to the tip of the straightened tail.
CLN = distance along the midline from the anterior edge of the nuchal scute
to the posterior termination of the midline. All animals measured were landed
at Puerto Cabezas, Nicaragua between November 1993 and January 1995.
Tail Body Mass (kg) Carapace Length (cm)
(cm) oo IND od IND
<86 >102 86-102
<92 >100 92-100
33-35 <110 >110
35-37 <110 >110
< 75 > 87 75 87
< 78 > 87 78 87
> 93 83 93
< 88 > 93 88 93
< 94 > 100 94-100
< 94 > 99 94 99
< 93 > 96 93-96
< 96 > 96
< 97 > 97