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-CAÑIZALES1, 2, 3, NÍNIVE ESPINOZA-RODRÍGUEZ1, 2, MARÍA A. RODRÍGUEZ1, 3, JORDANO PALMAR1,

MARÍA G. MONTIEL-VILLALOBOS1, 4, NATALIE E. WILDERMANN1, 3, 5, 6 and HÉCTOR BARRIOS-GARRIDO1, 3, 7, *

1Grupo de Trabajo en Tortugas Marinas del Golfo de Venezuela (GTTM-GV), Maracaibo, Venezuela. 2Centro de Rescate de Especies Marinas

Amenazadas (CREMA), Calle 114, 1.5 km Norte, 40201, Barva, Costa Rica. 3Laboratorio de Ecología General, Centro de Modelado

Científico (CMC), Facultad Experimental de Ciencias, Universidad del Zulia (LUZ), 4004, Maracaibo, Venezuela. 4Laboratorio de Ecología y

Genética de Poblaciones, Centro de Ecología, Instituto Venezolano de Investigaciones Científicas (IVIC), 1020-A, Caracas, Venezuela. 5Texas

Sea Grant at Texas A&M University, 4115 TAMU, College Station, TX 77843- 4115, USA. 6Harte Research Institute for Gulf of Mexico

Studies, 6300 Ocean Dr, Corpus Christi, TX 78412, USA. 7TropWATER, 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′

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

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

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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