MARINE AND FISHERY SCIENCES 34 (1): 113-119 (2021)
https://doi.org/10.47193/mafis.3412021010305
ABSTRACT. Leatherback turtle (Dermochelys coriacea) is highly impacted by fisheries’
bycatch worldwide. This study updates and estimates the leatherback turtle stranding records from
2001 to 2014 in the Gulf of Venezuela. Eighty-seven stranded leatherback turtles were documented
in the coast of the Gulf of Venezuela. Immature leatherback turtles were the most affected (85.5%)
and the highest number of strandings were recorded during the dry season (56.3%). Our findings
represent the minimum estimate of stranding events for the Gulf of Venezuela, especially consider-
ing the current lack of fisheries regulations. This is the latest update for the leatherback turtle strand-
ings in the Gulf of Venezuela and could help to create new management solutions in the area aiming
to minimize the impact on leatherback turtle populations in the Caribbean.
Key words: Immature, marine turtle, strand, IUU fishing, Guajira Peninsula, southern Caribbean.
Tortugas cardón (Dermochelys coriacea) en el Golfo de Venezuela: una actualización sobre las
evaluaciones de los varamientos 2001-2014
RESUMEN. La tortuga cardón (Dermochelys coriacea) está altamente impactada por las captu-
ras incidentales a nivel global. Este estudio actualiza y calcula los registros de varamientos de la tor-
tuga cardón desde 2001 hasta 2014 en el Golfo de Venezuela. Se contabilizaron 87 animales varados
en la costa del Golfo de Venezuela. El segmento poblacional más afectado fueron los individuos
inmaduros (85,5%) y el mayor número de registro de varamientos ocurrió en época de sequía
(56,3%). Nuestros resultados representan el mínimo estimado de muertes por varamientos para el
Golfo de Venezuela, especialmente dadas las condiciones actuales de ausencia total de regulaciones
formales a las pesquerías. El presente trabajo representa la más reciente evaluación de los varamien-
tos para esta especie en el Golfo de Venezuela, la cual podría ayudar a crear nuevas y mejores medi-
das de manejo en el área de trabajo, disminuyendo el impacto que afectan a las poblaciones de tor-
tuga cardón en el Caribe.
Palabras clave: Juveniles, tortuga marina, varamiento, pesca INDNR, Península de La Guajira,
Caribe sur.
113
*Correspondence:
hector.barriosgarrido@my.jcu.edu.au
Received: 15 January 2021
Accepted: 9 February 2021
ISSN 2683-7595 (print)
ISSN 2683-7951 (online)
https://ojs.inidep.edu.ar
Journal of the Instituto Nacional de
Investigación y Desarrollo Pesquero
(INIDEP)
This work is licensed under a Creative
Commons Attribution-
NonCommercial-ShareAlike 4.0
International License
Marine and
Fishery Sciences
MAFIS
NOTE
Leatherback turtles (Dermochelys coriacea) in the Gulf of Venezuela: an
updated stranding assessment 2001-2014
DANIELA ROJAS-CAÑIZALES
1, 2, 3
, NÍNIVE ESPINOZA-RODRÍGUEZ
1, 2
, MARÍA A. RODRÍGUEZ
1, 3
, JORDANO PALMAR
1
,
MARÍA G. MONTIEL-VILLALOBOS
1, 4
, NATALIE E. WILDERMANN
1, 3, 5, 6
and HÉCTOR BARRIOS-GARRIDO
1, 3, 7, *
1
Grupo de Trabajo en Tortugas Marinas del Golfo de Venezuela (GTTM-GV), Maracaibo, Venezuela.
2
Centro de Rescate de Especies Marinas
Amenazadas (CREMA), Calle 114, 1.5 km Norte, 40201, Barva, Costa Rica.
3
Laboratorio de Ecología General, Centro de Modelado
Científico (CMC), Facultad Experimental de Ciencias, Universidad del Zulia (LUZ), 4004, Maracaibo, Venezuela.
4
Laboratorio de Ecología y
Genética de Poblaciones, Centro de Ecología, Instituto Venezolano de Investigaciones Científicas (IVIC), 1020-A, Caracas, Venezuela.
5
Texas
Sea Grant at Texas A&M University, 4115 TAMU, College Station, TX 77843- 4115, USA.
6
Harte Research Institute for Gulf of Mexico
Studies, 6300 Ocean Dr, Corpus Christi, TX 78412, USA.
7
TropWATER, Centre for Tropical Water and Aquatic Ecosystem Research; College
of Marine and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia
The leatherback turtle (Dermochelys coriacea)
is one of the five species of marine turtles that use
the feeding ground areas in the Gulf of Venezuela
(Guada and Sole 2000). It is currently listed as
Endangered at regional level and also at national
scale by the International Union for Conservation
of Nature (IUCN) (NALWG 2019), and by the
Red Book of Venezuelan species (Rondón-
Medicci et al. 2015).
Most of the information about the species in
the Gulf of Venezuela has been derived from
stranding data (Acuña and Toledo 1994; García-
Cruz et al. 2020). However, stranding trends are
still in early stage of evaluation. Previous
research found that there is still a lack of informa-
tion regarding the seasonality and impacts of arti-
sanal fishing over this species in the study area.
This study aims to update the results presented by
Barrios-Garrido and Montiel-Villalobos (2016)
and merge records from 2001 to 2014 in the Gulf
of Venezuela.
Following previous research and protocol, this
study was carried out in the three main areas at
the Venezuelan Guajira Peninsula (Gulf of
Venezuela): the Upper Guajira; Middle Guajira;
and Low Guajira (Barrios-Garrido and Montiel-
Villalobos 2016) (Figure 1). We covered an
extension of 188.7 km of coastline (11° 36′ 27.5″
N; 71° 53′ 48.7″ W) including 14 landing sites,
villages and fishing ports. The Gulf of Venezuela
has two distinct seasons: a dry season (100 mm
mean rainfall from December to April) and a
rainy season (200 mm mean rainfall from May to
November) (Rodríguez and Morales 2000). Also,
this marine area is considered a key foraging
ground for leatherback turtles in Venezuela
(Guada and Solé 2000; Barrios-Garrido and Mon-
tiel-Villalobos 2016).
We evaluated leatherback turtle stranding data
and merged stranding network databases: for
2001-2007 assessed by Barrios-Garrido and
Montiel-Villalobos (2016); plus data collected
between 2008-2014 by the NGO Marine Turtle
Working Group in the Gulf of Venezuela. We
assessed each stranded animal based on formal
stranding register: GPS location, biometrical
measurements, and life stage of the stranded tur-
tle (immature or adult-size animals) (see details
in Barrios-Garrido and Montiel-Villalobos 2016).
A t-test was conducted to determine differences
among the number of records during the years of
the sampling period.
We evaluated the geographical and temporal
(annually and quarterly) distribution of the strand-
ings across the three main areas. Additionally,
strandings were classify as: 0 (alive); 1 (alive, but
subsequently died); 2 (dead, fresh carcass); 3
(dead; carcass fair; decomposing but internal
organs intact); 4 (dead, carcass poor condition;
advanced decomposition); 5 (dead, mummified
carcass with skin holding bones together); 6
(dead, disarticulated bones) (Meager and Limpus
2012). Finally, strandings were categorized based
on the cause of stranding: unknown or human
activity-linked (e.g., bycatch) (Kotch et al. 2006).
We found 87 stranded leatherback turtles along
the coastline of the Gulf of Venezuela. The high-
est number of encounters was reported in 2003
(25.3%, n = 22) and 2013 (17.2%, n = 15) (Figure
2), while in 2004, 2010 and, 2012 no stranding
events were documented. Significant differences
were found among the number of records
throughout the years of the sampling period (t-
value = 4.24; df = 10; p = 0.001719).
The highest percentage of strandings was
recorded during the dry season (56.3%, n = 49);
with most encounters documented in February
and April (52.9%, n = 46) (Figure 2). Finally,
most stranding encounters were in categories 3 to
6 (78.9%, n = 15) and four among the categories
0 (5.5%, n = 1), 1 (5.5%, n = 1), and 2 (11.1%,
n = 2). The majority of the standings’ causes were
unknown (63.2%, n = 55) and the remains pre-
sented evidence of human interactions (36.8%,
n = 32), mainly bycatch and intentional take.
Leatherback strandings were more frequent in
the Low Guajira (58.6%, n = 51), followed by the
Upper Guajira (33.3%, n = 29), with sporadic
114
MARINE AND FISHERY SCIENCES 34 (1): 113-119 (2021)
115
ROJAS-CAÑIZALES ET AL.: TORTUGAS CARDÓN EN VENEZUELA
Figure 1. A) Geographical location of the study area. B) Detailed map including the three main locations in the Gulf of Venezuela
separated by double-lines (Upper Guajira, Middle Guajira, and Low Guajira). Map created using Maptool (2002. SEA-
TURTLE.ORG, Inc. Available at http://www.seaturtle.org/maptool/).
72° 00′ W 71° 50′
71° 40′ 71° 30′ 71° 20′ 71° 10′ 71° 00′
11° 50′ N
11° 40′
11° 30′
11° 20′
11° 10′
11° 00′
B
A
Figure 2. Annually and monthly stranding events of leatherback turtles (Dermochelys coriacea) between 2001 and 2014 along
the coastline of the Gulf of Venezuela (N = 87).
Number of strandings events
0
5
10
15
20
25
2001 2002 2003 2005 2006 2007 2008 2009 2011 2013 2014
Year
Dec
Oct
Sep
Aug
Jul
Jun
May
Apr
Mar
Feb
Jan
events in the Middle Guajira (8.0%, n = 7) (Fig-
ure 3). Mean curved carapace length (CCL ± SD)
was 125.6 cm ± 21.4, ranging between 80-195 cm
(n = 55). Based on the measurements taken, most
of the stranded turtles were immatures (85.5%,
n = 47) with only 14.5% (n = 8) adults.
Eighty-seven stranded leatherback turtles have
been documented in the coast of Gulf of
Venezuela. The number of encounters found was
low compared with leatherback bycatch in
Trinidad Tobago and the Eastern Caribbean (Gass
and Eckert 2006; Connor Blades et al. 2019). The
number of leatherback turtles stranded found was
likely a conservative estimate, especially consid-
ering that fisheries-related mortality is usually
partially reported (Hamann et al. 2010; Hamelin
et al. 2017; Connor Blades et al. 2019). Further
research is necessary to understand how this is
affecting the species regionally.
Most of the stranded turtles were documented
in the Low and Upper Guajira, possibly linked
to local currents, tides, winds converge in both
areas, and offshore fisheries in the Low Guajira
(Barrios-Garrido and Montiel-Villalobos 2016).
Only seven leatherbacks were documented in
the Middle Guajira, may be related to biophysi-
cal characteristics of this area (Rojas-Cañizales
et al. 2020). Winds and sea currents have an
important role in where or whether a marine tur-
tle get stranded or not (Epperly et al. 1996). It is
necessary to assess local oceanographic vari-
ables to understand how leatherback turtle car-
casses move within the Gulf of Venezuela to
monitor key stranding areas.
A large portion of recorded leatherback turtles
(85.5%) was immature. The Gulf of Venezuela is
likely a migratory route and a foraging area. It is
possible that the immature leatherbacks were
using this area to move with adult individuals
(Barrios-Garrido and Montiel-Villalobos 2016),
in a similar way as previously documented by
James et al. (2005) in Canadian waters. The num-
ber of immature leatherbacks stranded was alarm-
ing and could negatively impact Caribbean popu-
lations, as it occurred in the Eastern Pacific
Regional Management Unit (Wallace et al. 2013).
Further research such as satellite tracking is need-
ed to understand the movements and the impact at
regional scale of the stranding trend.
Most records documented occurred during the
dry season. This seasonality might be related to
the leatherback nesting season that starts in March
116
MARINE AND FISHERY SCIENCES 34 (1): 113-119 (2021)
Figure 3. Size intervals (cm) of stranded leatherbacks (Dermochelys coriacea) found in the Upper Guajira, Middle Guajira, and
Low Guajira (N = 54). Dashed line represents the minimum size (< 145 cm of CCL) recorded for leatherback nesters in
Atlantic Ocean (Eckert 2002; Stewart et al. 2007).
Number of strandings events
20
18
16
14
12
10
8
6
4
2
0
80-90
Size class (CCL)
90.1-100
100.1-110
110.1-120
120.1-130
130.1-140
140.1-150
150.1-160
160.1-170
170.1-180
180.1-190
190.1-200
Upper Guajira
Middle Guajira
Low Guajira
at surrounding nesting beaches in the Caribbean
(Rondón-Medicci et al. 2011, 2015; Borrero-Avel-
laneda et al. 2015). Leatherback turtles travelled
extensively from the Caribbean throughout the
Atlantic increasing the interaction with fisheries
(Hays et al. 2004; Hamelin et al. 2017; Connor
Blades et al. 2019). Morover, these movements
might be associated to local food occurrence and
distribution (Fossette et al. 2008). Barrios-Garrido
et al. (2020) reported an adult leatherback turtle
that was tagged in French Guyana and found later
in the Upper Guajira, therefore suggesting that
leatherback turtles use the foraging area after
reproductive seasons. It is necessary to study the
connections between the Gulf of Venezuela and
the nesting areas in the Caribbean and Atlantic to
identify hotspots for the species and create region-
al management plans.
Most of stranded leatherbacks documented
were found in an advanced state of decomposi-
tion (78.9%), being difficult to determine the
cause of death (Veléz-Rubio et al. 2013). Com-
monly, stranding events are closely influenced by
fishery interactions (Nicolau et al. 2016), which it
is likely to be occurring in the Gulf of Venezuela;
however, due to the nature of our data it is diffi-
cult to establish these interactions as the main
cause of death. Currently, there is an information
gap on the consequences of bycatch and inten-
tional take in the area and its implications in the
ecosystem. Applying standardized protocols
could provide useful information in the future to
better understand the main cause of strandings in
the Gulf of Venezuela.
ACKNOWLEDGEMENTS
We thank to all the fishers, Wayuú clan leaders,
and GTTM-GV’s volunteers that contributed to
this study. This research was authorized by
Venezuela’s Environmental Ministry via scientif-
ic licenses and 828, 886, and 1224.
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