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This study analysed sea turtle strandings on the coast of Paraíba State, Northeastern Brazil, from August 2009 to July 2010. A total of 124 strandings were recorded in this period: green turtle Chelonia mydas (n = 106), hawksbill Eretmochelys imbricata (n = 15), olive ridley Lepidochelys olivacea (n = 2) and loggerhead Caretta caretta (n = 1). Of all turtles for which the Curved Carapace Length (CCL) was measured (n = 122), only 12 individuals (9.7%) were adults. Twenty individuals had synthetic anthropogenic debris in the gastrointestinal tract. Other traces of human interactions were observed in 43 individuals, such as injuries caused by entanglement in fishing lines or nets, collisions with vessels, direct contact with oil spills and lesions caused by sharp or spiked objects. Moreover, in 28.5% of the stranded turtles, the presence of external tumors was noticed, suggestive of fibropapillomatosis and in 9.7%, shark bite marks were observed. Of the 107 individuals that were sexed, 76 were females and 31 were males. Most turtles (72.6%) became stranded during the spring/summer (between October and March). We found evidence of human interactions (injuries) in half of the strandings, but in most cases it was not possible to determine if such interactions were the cause of death. A logistic regression found a significant relationship between CCL, ingestion of debris and lesions caused by sharks or spiked objects. Systematic data collection from stranded sea turtles can provide useful biological information, such as seasonal and spatial patterns in their occurrence and mortality, age structure, sex ratio and diet, as well as possible mortality causes.
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Braz. J. Biol., 2014, vol. 74, no. 2, p. 283-289 283283 Original Article
Patterns and inferred processes associated with sea turtle
strandings in Paraíba State, Northeast Brazil
Poli, C.a,b*, Lopez, LCS.a, Mesquita, DO.a, Saska, C.a,b and Mascarenhas, R.a,b
aDepartamento de Sistemática e Ecologia, Centro de Ciências Exatas e da Natureza, Universidade Federal da Paraíba - UFPB,
Cidade Universitária, Castelo Branco, CEP 58059-900, João Pessoa, PB, Brazil
bProjeto Tartarugas Urbanas, Associação Guajiru: Ciência - Educação - Meio Ambiente,
Av. Litorânea, Intermares, CEP 58310-000, Cabedelo, PB, Brazil.
Received July 16, 2012 – Accepted February 14, 2013 – Distributed May 31, 2014
(With 1 gure)
This study analysed sea turtle strandings on the coast of Paraíba State, Northeastern Brazil, from August 2009 to
July 2010. A total of 124 strandings were recorded in this period: green turtle Chelonia mydas (n = 106), hawksbill
Eretmochelys imbricata (n = 15), olive ridley Lepidochelys olivacea (n = 2) and loggerhead Caretta caretta (n = 1).
Of all turtles for which the Curved Carapace Length (CCL) was measured (n = 122), only 12 individuals (9.7%) were
adults. Twenty individuals had synthetic anthropogenic debris in the gastrointestinal tract. Other traces of human
interactions were observed in 43 individuals, such as injuries caused by entanglement in shing lines or nets, collisions
with vessels, direct contact with oil spills and lesions caused by sharp or spiked objects. Moreover, in 28.5% of the
stranded turtles, the presence of external tumors was noticed, suggestive of bropapillomatosis and in 9.7%, shark
bite marks were observed. Of the 107 individuals that were sexed, 76 were females and 31 were males. Most turtles
(72.6%) became stranded during the spring/summer (between October and March). We found evidence of human
interactions (injuries) in half of the strandings, but in most cases it was not possible to determine if such interactions
were the cause of death. A logistic regression found a signicant relationship between CCL, ingestion of debris and
lesions caused by sharks or spiked objects. Systematic data collection from stranded sea turtles can provide useful
biological information, such as seasonal and spatial patterns in their occurrence and mortality, age structure, sex ratio
and diet, as well as possible mortality causes.
Keywords: threatened species, human impact, beach strandings, green sea turtle.
Padrões e inferências associadas com encalhes de tartarugas
marinhas no Estado da Paraíba, Nordeste do Brasil
Este estudo analisou encalhes de tartarugas marinhas na costa do Estado da Paraíba, Nordeste do Brasil, de agosto
de 2009 a julho de 2010. Neste período, 124 encalhes foram registrados: tartaruga-verde Chelonia mydas (n = 106),
tartaruga-de-pente Eretmochelys imbricata (n = 15), tartaruga-oliva Lepidochelys olivacea (n = 2) e cabeçuda Caretta
caretta (n = 1). Dentre todas as tartarugas que tiveram o Comprimento Curvilíneo da Carapaça (CCC) medido
(n = 122), apenas 12 indivíduos (9,7%) foram considerados adultos. Vinte indivíduos tinham detritos antropogênicos
sintéticos no trato gastrointestinal. Em 43 indivíduos, outros vestígios de interações humanas foram observados, tais
como lesões causadas por emaranhamento em linhas ou redes de pesca, colisões com embarcações, contato direto com
derramamentos de óleo e lesões causadas por objetos perfurocortantes. Além disso, em 28,5% das tartarugas encalhadas,
foi observada a presença de tumores externos sugestivos de bropapilomatose e em 9,7%, foram observadas marcas
de mordidas de tubarão. Dos 107 indivíduos sexados, 76 eram fêmeas e 31 eram machos. A maioria das tartarugas
(72,6%) encalhou durante a primavera/verão (entre outubro e março). Foram encontrados sinais de interações humanas
(lesões) em metade dos encalhes, mas na maioria dos casos, não foi possível determinar se tais interações foram a causa
da morte. A regressão logística encontrou uma relação signicativa entre CCC e ingestão de detritos, lesões causadas
por objetos perfuro-cortantes e ataques de tubarões. A coleta sistemática de dados de tartarugas marinhas encalhadas
pode fornecer informações biológicas úteis, tais como padrões sazonais e espaciais na sua ocorrência e mortalidade,
estrutura etária, razão sexual, dieta, bem como possíveis causas de mortalidade.
Palavras-chave: espécies ameaçadas, impacto humano, encalhes de praia, tartaruga verde.
Braz. J. Biol., 2014, vol. 74, no. 2, p. 283-289
Poli, C. et al.
1. Introduction
Sea turtles are long-distance migratory animals and
occupy niches in different marine environments and
geographical regions throughout their different life cycle
stages, usually ranging from pelagic environments, as
hatchlings, to several coastal areas in their juvenile and
adult stages (Bolten, 2003). Due to migratory habits, sea
turtles are susceptible to threats in both offshore and coastal
environments (Bolten, 2003). Five sea turtle species use the
Brazilian coast for reproduction and feeding: loggerhead
(Caretta caretta Linnaeus, 1758), green (Chelonia mydas
Linnaeus, 1758), leatherback (Dermochelys coriacea
Vandelli, 1761), olive ridley (Lepidochelys olivacea
Eschscholtz, 1829) and hawksbill (Eretmochelys imbricata
Linnaeus, 1766) (Marcovaldi and Dei Marcovaldi, 1999).
All species are listed as threatened by extinction globally
(IUCN, 2011) and nationally (Martins and Molina, 2008).
Sea turtles face a wide variety of stressors, mainly
anthropogenic (Lutcavage et al., 1997). In Brazil, a
major cause of sea turtle mortality is linked to incidental
capture in shing artifacts (Mascarenhas et al., 2005;
Marcovaldi et al., 2006; Bugoni et al., 2008). Marine
pollution is another serious threat that causes habitat
degradation and turtle death through debris ingestion or
entanglement (Bjorndal et al., 1994; Ivar do Sul and Costa,
2007). Along most of the Brazilian coast, ingestion of
marine debris by sea turtles has frequently been reported
(Bugoni et al., 2001; Mascarenhas et al., 2004; Tourinho et al.,
2010; Guebert-Bartholo et al., 2011). Moreover, although
prohibited in most of the world, all sea turtle species have
been used for decades as a protein source, entailing the
consumption of their meat or eggs, or as raw material in
the manufacture of ornaments and artifacts (Marcovaldi
and Dei Marcovaldi, 1999; Campbell, 2003).
In addition to human threats, sea turtles suffer the impacts
of many types of disease, among which bropapillomatosis
(FP) is the most studied (Herbst, 1994). FP is a debilitating
disease and can be lethal, or may impair the animal’s ability
to feed or swim (George, 1997).
Part of the dead or debilitated animals end up stranded on
beaches, and this performs a fundamental role in ecological
studies and species conservation (Epperly et al., 1996).
Systematic data collection from stranded sea turtles can
provide useful biological information, such as seasonal
and spatial patterns in their occurrence and mortality, age
structure, sex ratio, diet, interannual variations associated
with climatic or anthropogenic events, as well as possible
causes of mortality (Bjorndal, 1999). In Paraíba State,
Northeastern Brazil, strandings of green, hawksbill, olive
ridley and loggerhead sea turtles have been recorded
(Mascarenhas et al., 2005; Mascarenhas and Iverson, 2008).
Given the current vulnerability of all sea turtle species,
the systematic study of strandings, with an emphasis on
research into their causes, is becoming increasingly urgent.
This study aimed to examine sea turtle strandings on the
coast of Paraíba State from August 2009 to July 2010,
testing the following hypotheses: (1) The occurrence of
different species strandings is not homogeneous among
species and seasons; (2) There is signicant difference in
the occurrence of strandings among life stages and sexes;
(3) There is a relationship between Curved Carapace Length
(CCL) and events associated with stranding.
2. Material and Methods
The study was conducted from August 2009 to July
2010 on the coast of Paraíba State, Northeastern Brazil,
along 15 km of urban beaches in the municipalities of João
Pessoa (7°08’S and 34°48’W) and Cabedelo (7°01’S and
34°49’W) (Figure 1). Daily monitoring was performed
between Bessa (7°05’S and 34°49’W) and Ponta de
Campina (7°01’S and 34°49’W). For the remaining area
(Cabo Branco, Tambaú and Manaíra beaches), stranding
observations were reported to the researchers through
partnerships with environmental agencies and the local
community, via a telephone line, “SOS Turtles”.
In the case of dead individuals, the external data were
collected at the stranding location, such as the carcass
decomposition stage, evidence of anthropogenic interaction,
presence of tumors, presence of individual marks and
evidence of interaction with other fauna. The carcass
decomposition stage was divided into categories: a) without
decomposition evidence; b) moderate decomposition; and
c) advanced decomposition. CCL and the Curved Carapace
Width (CCW) were measured using a exible tape with
0.1 cm accuracy. Individuals were classied as juveniles
or adults based on CCL measurements, considering the
minimum values of nesting females in nearby beaches (see
Baptistotte et al., 2003; Grossman et al., 2007; Marcovaldi
and Chaloupka, 2007; Silva et al., 2007; Santos et al., 2010
for reference values).
After the collection of external data, carcasses were
necropsied to collect additional data such as sex by
gonad examination, observation of internal tumors and
digestive tract analysis in search of anthropogenic material.
Gastrointestinal tracts were removed from the esophagus
to the nal portion of the intestine, and each organ was
analysed separately. Gastrointestinal content was washed
using sieves and, when present, anthropogenic debris was
Figure 1. Strandings distribution in the different months
between August 2009 and July 2010 on the Paraíba coast.
Braz. J. Biol., 2014, vol. 74, no. 2, p. 283-289 285
Patterns associated with turtle strandings
separated from organic items. Animals stranded alive were
moved to rehabilitation in the “Projeto Tartarugas Urbanas”
after external data collection. Animals that died during
rehabilitation underwent the same necropsy procedure.
Homogeneity in the occurrence of different stranded
species was conrmed using a Kolmogorov–Smirnov
test (Ayres et al., 2007). Other tests were performed only
for species where the number of strandings was above
20 individuals. A Chi-square test was applied to verify
homogeneity in the occurrence of juvenile and adult strandings
(Ayres et al., 2007). We performed a Kolmogorov–Smirnov
test (Ayres et al., 2007) to test whether the occurrence of
anthropogenic interactions was homogeneous. We also
performed a logistic regression (Fox, 2005) between
the CCL and the possible causes of stranding in order to
determine whether there was a relationship between the
size of the turtle and the different interactions observed. A
Chi-square test was applied to verify homogeneity in the
occurrence of male and female strandings (Ayres et al.,
2007). A Chi-square test was applied to conrm differences
in the occurrence of strandings in the winter and summer,
and a Rayleigh test was also performed in order to highlight
the period of highest stranding occurrence (Ayres et al.,
2007). For all statistical analyses, results were considered
signicant at an alpha 0.05 level (Zar, 1999).
3. Results
From August 2009 to July 2010, 124 sea turtle strandings
were recorded in the study area. Fifteen turtles (12.1%)
were stranded alive but died during the rehabilitation
period. Regarding the decomposition status of the carcass,
19 (17.4%) were fresh, 29 (26.6%) were moderately
decomposed and 61 (56.0%) were in an advanced state
of decomposition. Parts of the carcasses were missing
in 20 individuals (16.1%). A total of 98 necropsies were
performed. The occurrence of stranded species was not
homogeneous (Kolmogorov–Smirnov maximum deviation
= 0.604, p < 0.01): 106 green turtles (85.4%), 15 hawksbill
(12.1%), two olive ridley (1.6%) and one loggerhead (0.9%).
Regarding age class, for all stranded turtles that were
measured (n = 122), only twelve individuals (9.7%) could
be considered adults (Table 1). The CCL and CCW of two
green turtles could not be measured due to the lack of a
partial or whole carapace. There was a signicant difference
between the occurrence of juvenile and adult green turtles
YATE S = 40.9, p = 0.0001), with nine adults observed
(8.6%, n = 9/104); for the other species, three hawksbills
and the only loggerhead were considered adult (Table 1).
A total of 98 gastrointestinal tracts were analysed,
of which 20 (20.4%) contained synthetic anthropogenic
debris: 13 green turtles (65.0%), 5 hawksbill (25.0%) and 2
olive ridley (10.0%). Moreover, 43 individuals (41.3%) of
the 104 whole carcasses showed other evidence of human
interactions, such as injuries caused by entanglement in
lines or nets (33.6%), collisions with vessels (3.8%), sharp
or spiked objects (3.8%) and direct contact with oil spills
(0.96%). The proportion of anthropogenic interactions was
not homogeneous for green turtles (Kolmogorov–Smirnov
maximum deviation = 0.383, p < 0.01).
In addition to the evidence of human interactions, other
carcasses showed signs that could be linked to causes of
debilitation that had possibly resulted in the stranding. In
28.5% (n = 30/105) of the stranded turtles, considering
the carcasses that were intact, the presence of external
tumors was noted, suggestive of FP, and even those that
were incomplete showed the same type of tumors. All
individuals that presented these tumors were green turtles,
with CCLs ranging between 37.9 and 76.4 cm (= 54 cm).
Shark bite marks were observed in 9.7% (n = 124) of the
carcasses. Of the 12 animals that showed evidence of
interactions with sharks, only two had a CCL < 75 cm,
indicating that they were either large juveniles or adults.
A logistic regression, performed for green sea turtle
data, showed a signicant relationship between the CCL
and ingestion of anthropogenic debris (estimate = –0.048,
p = 0.03); between the CCL and injuries caused by sharp
or spiked objects (estimate = 0.072, p = 0.01); and between
the CCL and interactions with sharks (estimate = 0.046, p =
0.001). The regression revealed no signicant relationship for
the remaining observations of possible causes of stranding
(entanglement in lines and nets, collisions with vessels,
contact with oil and tumors suggestive of FP_ Table 2).
Regarding sex, in 17 carcasses (13.7%) it was not
possible to determine gender due to the advanced stage
of decomposition. Of the 107 individuals sexed, 76 (71%)
were females and 31 (29%) were males. Female green
sea turtles predominated (χ
= 8.8, p = 0.003): of
91 individuals sexed, 66 (72.5%) were females and 25
(27.5%) were males. Regarding seasonality, strandings
predominated in the spring/summer (76.6%, n = 90;
= 12.3, p = 0.0004). A Rayleigh test conrmed
that the distribution of stranding occurrences was not
uniform (R = 38.9, p < 0.01), indicating a higher incidence
of strandings between October and February (Figure 1).
Table 1. Curved Carapace Length (CCL) and Curved Carapace Width (CCW) (mean and standard deviation) of the turtle
species collected in strandings on the Paraíba coast between August 2009 to July 2010. The maximum and minimum are in
Species CCL (cm) CCW (cm)
C. mydas (n = 104) 56.6 ± 21.5 (24.0-123.5) 52.2 ± 20.3 (22.2-111.7)
E. imbricata (n = 15) 48.8 ± 21.6 (30.9-91.2) 43.3 ± 19.9 (26.0-84.7)
L. olivacea (n = 2) 61.6 ± 2.3 (60.0-63.3) 66.0 ± 2.2 (64.4-67.6)
C. caretta (n = 1) 93.5 86
Braz. J. Biol., 2014, vol. 74, no. 2, p. 283-289
Poli, C. et al.
4. Discussion
Our results corroborate the study of Mascarenhas et al.
(2005) in the same area, showing that green turtles are
the most frequently stranded species. The same results
have been found along the Brazilian coast, such as in
Rio de Janeiro (Reis et al., 2009), Rio Grande do Sul
(Bugoni et al., 2001) and Paraná (Guebert-Bartholo et al.,
2011). Green turtles are found in many feeding grounds
on the Brazilian coast (Marcovaldi and Dei Marcovaldi,
1999; Grossman et al., 2007), including the coral reefs of
the Paraíba coast (Mascarenhas et al., 2005), which may
explain the predominance of this species in strandings.
Hawksbills occurred in signicantly lower numbers
compared to green sea turtles; despite the Paraíba beaches
having been recognised as a nesting site for this species
(Mascarenhas et al., 2003), only three individuals were
considered sexually mature, and so these strandings
were not associated with their presence during the period
of reproductive activity in the area. It is probable that
hawksbill, olive ridley and loggerhead specimens died
and became stranded between the migration from their
nesting area to different foraging grounds. Whiting et al.
(2007), in a study of olive ridley turtles in Australia,
suggest that after the nesting season all turtles travel
between 180 and 1050 km to different foraging areas, using
coastal and continental habitats, and are able to forage
during migration before reaching their foraging grounds.
Telemetry studies in Brazil indicate that hawksbills migrate
between nesting areas in Bahia and foraging grounds in
Ceará State (Marcovaldi et al., 2011), and that there is a
migratory corridor along the entire coast of Northeastern
Brazil for loggerheads (Santos et al., 2011). Telemetry
studies for olive ridley turtles in Brazil highlight that there
is a displacement from the Espírito Santo coast to Pará
State (Castilhos et al., 2011). Beyond telemetry studies,
analysis of strandings along the Brazilian coast indicates
that turtles could be migrating to more southern feeding
areas, such as in the study of Reis et al. (2010a), which
suggests that feeding areas for olive ridley turtles are
found on the Rio de Janeiro coast. Considering this large
home range, and all the natural and anthropogenic risks to
which these animals are exposed, it is very plausible that
they were stranded during migration from their nesting
area to different foraging grounds.
Relative to life stage, similar studies in Brazil and
elsewhere have also reported a higher incidence of juvenile
strandings, irrespective of species (Bugoni et al., 2001;
Chaloupka et al., 2008; Reis et al., 2009). One explanation
for the high incidence of juvenile strandings is based on
their cycle life. Juveniles of the green, hawksbill, olive
ridley and loggerhead turtles usually migrate from ocean
areas to neritic environments, where they complete their
development and where there is greater food availability
(Bolten, 2003). However, coastal areas typically support
greater human activity and a greater accumulation of debris
(Aguirre and Lutz, 2004), which makes the sea turtles more
susceptible in these environments. Regarding sex ratio,
females predominated, as is the case in previous reports
of the area (Mascarenhas et al., 2005). Grossman et al.
(2007), in a study on green turtles in Atol das Rocas, also
report a higher frequency of females. The greater number
of females stranded is probably due to the fact that females
are more common in natural populations, in spite of there
being no studies that report females to be more susceptible
to threats than males in the marine environment.
It is evident in the present study and has been reported
elsewhere that human activity remains the main cause
of sea turtle mortality worldwide. In the present study,
shing activities followed by marine pollution were found
to be the main threats to turtles on the Paraíba coast. The
predominance of entanglement with shing apparatus as
the main human interaction registered in the stranded turtles
corroborates other studies where shing activity appears to
be one of the most important anthropogenic-related sources
of sea turtle mortality in the world (Marcovaldi et al., 2006;
Bugoni et al., 2008; Casale et al., 2010). In Paraíba State,
shing is mainly artisanal, comprising sailboats and small
motorboats shing in shallow waters near the coast and in
estuaries, deploying gillnets, hook-and-lines and shing
by manual collection (IBAMA, 2008). In lobster shing
on the Paraíba coast, 73% of the shermen carry out their
activities on the reefs and 24% between the reefs and the
beaches, using gillnets in 49% of cases (Oliveira et al.,
2009). Is important to note that this type of shing activity
is very dangerous for sea turtles, as has been reported by
Lima et al. (2010).
The present study showed that ingestion of marine
debris, especially plastic, is an important threat to sea
turtles, with the smaller green sea turtles having a higher
Table 2. Results of logistic regression performed between CCC and the possible causes of Chelonia mydas strandings.
Possible cause of stranding Estimate Stand. Error Z value Pr(>|z|)
Ingestion of marine debris –0.048 0.023 –2.076 0.03*
Entanglement in nets and lines 0.001 0.010 0.129 0.8
Collisions with vessels –0.017 0.033 –0.514 0.6
Injuries caused by sharp or spiked objects 0.072 0.030 2.364 0.01*
Contact with oil spills –0.138 0.139 –0.994 0.3
Shark attack 0.046 0.014 3.107 0.001*
Tumors suggestive of FP –0.007 0.010 –0.745 0.4
* Statistical signicance.
Braz. J. Biol., 2014, vol. 74, no. 2, p. 283-289 287
Patterns associated with turtle strandings
probability of ingesting plastic debris compared to larger
ones, conrming the results of previous studies (Balazs,
1985; Plotkin and Amos, 1990). Synthetic materials are
currently recognised as an important pollutant in marine
and coastal environments, and are reported in many studies
as the main type of debris found in these habitats (Ivar do
Sul and Costa, 2007; Ryan et al., 2009). The physical and
chemical effects of ingesting marine debris on sea turtles are
widely described in the literature (McCauley and Bjorndal,
1999; Bugoni et al., 2001; Tourinho et al., 2010). These
effects can be sub-lethal or lethal (Mascarenhas et al.,
2004; Tourinho et al., 2010), and therefore this interaction
is regarded as an important cause of stranding. Sea turtles
are prone to the ingestion of solid residues, which may
occur intentionally, when these residues are confused with
their natural foods or accidentally, when they are ingested
with food (Mrosovsky et al., 2009). Green sea turtles are
particularly prone to ingesting a large amount of marine
debris, mainly plastic, since it usually adheres to their main
food resource, the algae (Reis et al., 2010b).
In addition to the ingestion of anthropogenic debris, it
was possible to observe extreme oil contamination in the
entire body of a single individual, including the oral and
nasal cavities. The individual observed in this study was
an isolated case of visible contamination by oil, indicating
that the number of sea turtles on the Paraíba coast affected
by contact with oil spills would appear to be low.
Collision with vessels is further evidence of human
interaction being related to strandings, and is often the
cause of sea turtle death. Casale et al. (2010) point out
that collision with vessels was the second most common
cause of sea turtle death in the Mediterranean. However,
in the present study this interaction was not very common:
the strandings indicated that collisions occurred with the
carcass, not with a living turtle. Regarding evidence of
intentional injuries caused by sharp or spiked objects, two
main reasons are sustained to justify these activities: the use
of turtle meat for food and of the carapace keratin plates
for manufacture of ornamental items, or shing artifact
protection when animals, particularly large ones, are caught
and, in their struggle, rip the nets. This is corroborated by
logistic regression, which showed that larger individuals are
more susceptible to these types of injuries. The use of the
meat for consumption, and the carapace for the preparation
and sale of ornamental items has been reported in some
Brazilian cities (Marcovaldi and Dei Marcovaldi, 1999).
The occurrence of tumors in green turtles was expected,
since FP disease is recognized as more frequently affecting
this species (Aguirre and Lutz, 2004; Foley et al., 2005;
Reis et al., 2010b). Mascarenhas and Iverson (2008) report
tumors suggestive of FP in 26% of the strandings observed
on the Paraíba coast. Compared to that study, the results of
the present study showed a small increase in the incidence
of these tumors, and, moreover, we observed the presence
of both external and internal tumors in three animals,
especially in the lungs and intestine. The higher incidence
of tumors in individuals with CCLs of between 30 and
80 cm corroborates previous studies that report juveniles
as those that are mostly affected by FP (Aguirre and Lutz,
2004; Chaloupka et al., 2008). Foley et al. (2005) suggest
that the lack of FP in the smaller size classes (up to 30 cm)
could be explained by a lack of sufcient time for disease
symptoms to appear and, later, when these individuals
begin to migrate to coastal areas, they are exposed to a
greater concentration of pollutants (a possible co-factor
associated with FP), which could contribute to triggering
the disease. The sharp fall in the prevalence of the disease
in animals with CCLs < 80 cm could be explained by a
regression of tumors with age, or as a result of mortality
of individuals with FP before they have reached a larger
size (Foley et al., 2005). In addition, Van Houtan et al.
(2010) in their study reveal the relationship between turtle
size, eutrophication of foraging areas and the incidence of
invasive algae with the emergence of FP in green turtles.
By correlating disease with environmental factors, the
occurrence of FP can be used to evaluate ecosystem health
(Reis et al., 2010b).
The signicant seasonality observed in the occurrence of
strandings is probably related to the increase of anthropogenic
activities combined with the turtles migrating to their
nesting grounds. Fishing activities are more intense along
the Paraíba coast during the spring and summer (IBAMA,
2008). Moreover, during this period the movement of tourist
boats and the accumulation of marine debris on beaches
are both greater in this area (Mascarenhas et al., 2008).
We conclude that, despite conservation efforts and the
current Brazilian laws that penalize harmful practices that
threaten species, a range of human activities still endanger
sea turtle survival in the long-term. Fishing remains a
serious problem on the Paraíba coast, and interaction with
anthropogenic debris, as well as the signicant incidence of
FP, reveals a worrying environmental degradation. Urgent
measures are necessary, such as an increase in environmental
education activities and programs of regeneration and
environmental protection. Although there are numerous
studies on strandings of all sea turtle species, continued
monitoring is necessary along the entire Brazilian coast.
Furthermore, studies of population size, including tagging,
genetic analyses and behavioural studies, will be extremely
important in estimating the impact of mortality in this
specic population.
Acknowledgements – We would like to thank the entire team
of volunteers of Projeto Tartarugas Urbanas (Associação
Guajiru) for their help in eld work, the Coordenação de
Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
for their nancial support, CNPq for a research fellowship
for DOM, and the Programa de Pós-graduação em Ciências
Biológicas da Universidade Federal da Paraíba for supporting
this study.
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... Analysis of sea turtle stranding data is an important source of information on species biology, as spawning areas and feeding sites, in addition to providing subsidies for implementing sustainable practices and conservation plans Poli et al. 2014;Senko et al. 2014;Reis et al. 2017;López-Mendilaharsu et al. 2020). The registration of stranded marine organisms has been recurrent on the coast of Brazil (Coelho 2009;Lopes-Souza et al. 2015;Monteiro et al. 2016) including the Rio de Janeiro State (Reis et al. , 2010(Reis et al. , 2017Carvalho et al. 2015;Werneck et al. 2018;Tagliolatto et al. 2019a), due to the efforts of beach monitoring projects and the constant threats to the diverse populations in the marine ecosystem. ...
... Stranded sea turtles are commonly found dead at the various points already sampled along the South Atlantic coast (Reis et al. , 2017Vélez-Rubio et al. 2013;González-Carman et al. 2014;Poli et al. 2014;Lopez-Souza et al. 2015;Tagliolatto et al. 2019a). The large number of juveniles in an advanced state of decomposition indicates the large time interval between death and stranding, being an indication that they are suffering severe threats in the marine ecosystem, accelerating the decline in population densities (Guebert et al. 2013;Carvalho et al. 2016). ...
... Seasonality did not show a significant relationship with the richness and abundance of sea turtle stranding; however, the largest records number occurred in summer and spring, as observed in other coastal regions of Brazil (Poli et al. 2014;Lopes-Souza et al. 2015). During these seasons, sea turtles migrate to the coast to complete their reproductive periods and nest on the beaches (Camillo et al. 2009). ...
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The south-western region of the Atlantic Ocean has feeding and nesting areas for the five species of sea turtles registered in Brazil, which are in different degrees of extinction threat, mainly due to an- thropogenic factors. Fishing and the ingestion of solid waste, were identified as causing stranding and the mortality of sea turtles. In this work, data from the monitoring of beaches in the Municipalities of Macaé and Rio das Ostras, important oil zone in Brazil, in the north-central region of the State of Rio de Janeiro, were used in order to analyse the effects of seasonality on the sea turtle stranding. The monitoring was carried out daily from September 2017 to June 2019, in a study area covering 23.8 km long beach. Stranding data were obtained from active (n = 126) and passive (n = 66) monitoring of beaches and included the records of Chelonia mydas (n = 151), Caretta caretta (n = 23), Lepido- chelys olivacea (n = 14), Dermochelys coriacea (n = 2) and Eretmochelys imbricata (n = 1). The largest stranding record occurred in the summer (n = 61) and spring (n = 60), a period compatible with the reproductive season of the species. The results obtained in this study emphasise the importance of the analysis of strandings of sea turtles, which provide relevant data on the biology of the group, the intra and interspecific dynamics and the state of conservation of these animals.
... 1766), and Lepidochelys olivácea (E. 1829) (Schwartz 2000;Barbieri 2009a;Poli et al. 2014. ...
... 1766), and Lepidochelys olivácea (E. 1829) (Schwartz 2000;Barbieri 2009a;Poli et al. 2014. ...
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Stranded is the term used to refer to a marine animal found on land that does not have the ability to return to the sea (Branco et al. 2015). Stranded marine animals are often observed on beaches around the world, and the reasons for this are varied, ranging from anthropic and fishery interaction to disease, marine pollution, and even due to the occurrence of storms (Barbieri 2009a, b). There are studies that attempt to investigate which are the factors more determinants for the marine animals that end up dead on the beaches. The stranding monitoring is a useful tool to know and learn more about the species and their relationship with the environment. Meteorological and oceanographic phenomena can generate intense winds and wave heights above normal, intensify marine currents, and cause the heating or cooling of sea surface temperatures (Tavares et al. 2016; Melo 2017). These events may affect the survival of a species due to exhaustion, which influences the displacement of individuals and their search for food, as well as the arrival of these animals on the beaches by drifting carcasses (Barbieri et al. 2007). The study of these stranded animals may provide the necessary knowledge to direct conservation efforts and provide data for assessing the mortality rate of taxonomic groups, causes of death, seasonality of events, and associations with oceanographic, meteorological, and anthropogenic variables
... Previous studies in this region have recorded considerably less stranding records-in the order of tens (e.g. Poli et al., 2014), hundreds (Table 3), organized by components of the stranding probability (time, space, occurrence, death, drift). (a) Austral seasons, (b) latitude (degree), (c) sex (proportion of female/male), (d) body size (average curved carapace length, m), (e) average chlorophyll-a concentration (mg m À3 ) at the 20-50 km isobaths, (f) average sea surface temperature ( C) at the 20-50 km isobaths, (g) average salinity (practical salinity units) at the 20-50 km isobaths, (h) body condition (proportion bad/good), (i) pathology (proportion presence/absence), (j) decomposition state (mean decomposition code), (k) average Significant wave height (m) at the 20-50 km isobaths. ...
Sea turtles are globally threatened due to short-and long-term exposure to anthropogenic activities. Many life-history traits make it difficult to study these species in the wild. Stranding events provide invaluable data to infer key aspects of sea turtle ecology, such as regional occurrence , health status, mortality rates, and potential threats. In this study, we investigate spatial and temporal patterns of sea turtle occurrence and mortality in the southwestern Atlantic Ocean based on a systematic, large-scale survey programme covering 1040 km of coastline during 732 d of two consecutive years. From the 12 571 animals recovered, juvenile green turtles were the most common (90.4%), but four other species were also recorded. A significant non-linear effect of time and space in the number of stranding events was observed. The most parsimonious mixed linear model further indicated that stranding events were influenced by individual (sex, size), health (body condition, pathologies, decomposition), and oceanographic factors (chlorophyll-a, sea surface temperature, salinity, wave height). More than simply V C International Council for the Exploration of the Sea 2020. All rights reserved. For permissions, please describing the spatiotemporal occurrence and aspects of sea turtles' life history in an otherwise understudied area, this intensive field study provides evidence for relatively high mortality rates-an essential baseline information for guiding conservation efforts.
Shipwrecks have been accidentally and deliberately deployed worldwide, becoming artificial reefs for tourist attractions and habitats for marine species. Recreational divers often visit wrecks and post images on Instagram – a popular social network for image circulation. Here we evaluated if such images could be used as a data source for surveying sea turtles in shipwrecks and assessing diver–sea turtle interactions. We targeted the coast of Pernambuco in Brazil, which has over 100 shipwrecks. We inspected public videos and photos posted on Instagram from October 2010 to April 2020. We used 20 tags in our search, which led to 2353 images (210 videos; 2143 photos). A total of 220 posts depicted sea turtles (189 photos and 31 videos; 41 sea turtles in videos and 199 in photos) and their enhanced quality‐facilitated species identification. We detected Caretta caretta (loggerhead sea turtle), Chelonia mydas (green sea turtle) and Eretmochelys imbricata (hawksbill sea turtle). Turtles were found in 13 shipwrecks, all with bathymetry up to 30 m. Photos and videos provided the same proportion of images of each turtle species. Nevertheless, from a temporal perspective, this scenario changed. All three species were observed in photo posts in 4 of the 9 full years considered, whereas all three species were only observed in 1 year in the video posts. We registered four types of diver–turtle interactions from videos: ‘abrupt approach, chase, touch and pose’. We classified ‘abrupt approach, chasing and touching’ behaviours as major disturbances as they altered the turtles’ behaviours. We classified ‘pose’ as a minor disturbance as it caused no apparent change in turtle behaviour. Chasing was the most frequently observed interaction. Instagram is a useful complementary tool that can aid in the surveillance of sea turtles in shipwrecks. However, the limitations of this type of data and adequate data filtering criteria must be considered. Instagram can be used as a complementary tool that can aid in the surveillance of sea turtles in shipwrecks. However, the limitations of social media data and adequate data filtering criteria must be considered.
The ingestion of anthropogenic plastic debris by marine wildlife is widespread in the Mediterranean Sea. The endangered status (in the IUCN Red List) of Loggerhead turtle (Caretta caretta, Linnaeus, 1758) is a consequence of its vulnerability. In this study, macro-/meso-plastics (5–170 mm) collected from faeces of twelve loggerhead turtles rescued (live) in the Aeolian Archipelago (Southern Tyrrhenian Sea, Italy) were analyzed by size, weight, shape, color and polymer type through Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR). The defecation rate during hospitalization (7–14 days) varied among turtles (from 0.08-0.58). The mean number of plastic expulsions (2.7 ± 1.8 items for turtle) was higher during the 5th day of hospitalization (Kruskal-Wallis test, P = 0.01). However, the mean number of plastic-like items defecated during the common days of hospitalization did not vary among turtles (Kruskal-Wallis test, P > 0.05). All turtles were found to have ingested plastic. A total of 114 debris items were recovered from their faeces, 113 of which were identified as plastic. Their color was mostly white-transparent (64.9%) and light (19.3%). Shape was mainly fragments (52.6%), sheets (38.6%), followed by nylon, net-fragments, elastic plastic, foamed plastic and industrial granules (8.8%). Meso-plastics (5–25 mm) represented 72% of the total number of debris and were found more frequently in turtle with Curved Carapace Length (CCL) ≤ 60 cm (CCL = 30–60 cm, n = 5) than those with CCL >60 cm (CCL = 60–71 cm, n = 7). Plastic items were composed mainly of polyethylene (48.2%) and polypropylene (34.2%). Polypropylene (R² = 0.95, P < 0.001) and polyisoprene (R² = 0.45, P = 0.017) were more common in meso-plastics while polyethylene (R² = 0.44, P < 0.01) in macro-plastics. Finally, high-density polyethylene, polyvinyl chloride, polyamide and polyurethane were also found in some turtles. This study reveals high spreads of plastic contamination in faeces of both turtles with CCL ≤60 cm and CCL >60 cm, particularly vulnerable to the increasing quantity of floating plastic into their foraging sites highlighting the need of further research to associate debris ingestion with turtle diet and their size.
For decades, the Brazilian north-east coast has been a recognized feeding area for five sea turtle species. However, it still lacks information about stranding patterns. A decade of a beach monitoring programme (from 2010–2019) provided information on the composition, abundance and spatio-temporal distribution of stranded sea turtle species along a semiarid coast in the western equatorial Atlantic. A total of 905 individuals of four species were recorded in a route of ~130 km. The most stranded group was the juvenile green turtles ( Chelonia mydas ), followed by Lepidochelys olivacea , Eretmochelys imbricata and Caretta caretta . The strandings present a seasonal and geographic pattern, and therefore any conservation measure to be implemented must consider these patterns. Also, the possible occurrence of fibropapillomatosis tumours calls for additional studies to understand its causes. Lastly, stranded sea turtles eventually show marks of fishery interaction, which indicate the need for environmental education programmes with fishing communities.
For the first time, the qualitative and quantitative characteristics of marine debris ingested by six hawksbill (Eretmochelys imbricata) and seven olive ridley (Lepidochelys olivacea) sea turtles from the Gulf of Oman coast of the United Arab Emirates were investigated. The numeric and gravimetric proportions of ingested marine debris obtained from the esophagus, stomach and intestines were quantified following categories of presumed sources, Marine Strategy Framework Directive (MSFD), rigidity, color and plastic polymer types. Marine debris was observed in 28.6% of olive ridley (x‾: 2.00 items; 4.83 g) and 83.3% of hawksbill specimens (x‾: 6.00 ± 2.32 items; 0.32 ± 0.24 g). Overall, the results of this preliminary study suggest that hawksbill sea turtles were ingesting marine debris at higher frequencies and that plastics were observed to be the most predominant debris ingested. However, non-plastic rubbish, particularly metallic fishing gear (fish hooks and fish traps), were observed to present lethal hazards for both species.
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Sea turtles are subject to a wide range of human threats. Information collected from sea turtles found dead or debilitated (termed strandings) can provide valuable insights into these threats. In recent years, extensive beach monitoring projects implemented along the entire coast of Brazil (7,367 km) have facilitated data collection on regional sea turtle strandings. Here, we compiled stranding data from the Santos Basin in the state of Rio de Janeiro, Brazil, from 19 September 2016 to 19 September 2019. During this period, we recorded 3,957 sea turtle strandings of which 3,508 were dead turtles. We recorded five turtle species including 3,587 Green Turtles (Chelonia mydas), 242 Loggerhead Turtles (Caretta caretta), 76 Olive Ridley Turtles (Lepidochelys olivacea), 18 Leatherback Turtles (Dermochelys coriacea), eight Hawksbill Turtles (Eretmochelys imbricata), and 26 unidentified individuals. From all species, 12 were oceanic-stage juveniles, 3,663 were neritic-stage juveniles, and 147 were adults. A total of 539 strandings (13.6%) showed signs of anthropogenic interactions: 318 involved fishing gear, 125 involved watercrafts, 90 showed evidence of direct injuries from humans, four involved plastic items, and two involved oil pollution. Our results suggest that fisheries bycatch and watercraft collisions (mainly in bays) are the predominant threats to Green Turtles in the state Rio de Janeiro. It also appears that mortality of Loggerhead, Olive Ridley, and adult Leatherback Turtles is associated with fishing activities in feeding areas or in migratory corridors between feeding and breeding areas.
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The present study aims to describe the ontogenetic changes in the skull of the loggerhead turtle, Caretta caretta by focusing on the stages of development in the western South Atlantic Ocean. Our hypothesis is based on the premise that changes in feeding habits will reflect changes in the shape and/or size of the skull. The existence of changes in skull of the loggerhead turtle were analyzed using traditional and geometric morphometrics on skulls collected from stranded individuals in the southern Brazilian coast. As a general result, a transformation pattern was observed: from younger specimens with smaller, elongated and flattened skulls towards a larger, rounded and more robust skull in older specimens. It is suggested that these skull changes are associated with the diet shift of the loggerhead turtle specimens, providing the skull with greater mechanical resistance and enabling a change in feeding strategy from soft organisms to hard-shelled preys. This result highlights the importance of southern Brazilian coast for the life cycle of the loggerhead turtle. In this region, the individuals undergo the process of ontogenetic diet shift, changing their skull shape to adapt to the newly occupied niche and ensuring the ecological success of the species.
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O diagnóstico da pesca foi realizado entre os meses de julho e outubro de 2007, através de entrevistas baseadas em 37 questões, visando o levantamento socioeconômico da comunidade pesqueira e investigar o interesse dessa população em participar de atividades produtivas que complementassem a sua renda familiar. Foram entrevistados 100% dos pescadores em atividade na região, após a realização de um censo prévio na comunidade. A renda mensal média da maioria dos lagosteiros varia entre R$ 201,00 e R$ 400,00. Aqueles que têm renda inferior a R$ 200,00 complementam a mesma com atividades paralelas como construção civil, atividades de caráter informal e comércio. As comunidades de lagosteiros das praias do Seixas e da Penha caracterizam-se pelo atual ingresso de indivíduos mais jovens, que fazem uso do recurso (38% tem até 20 anos), pela modificação gradativa na arte de pesca, segundo as modificações impostas pela lei, e pela ausência de fiscalização quanto às políticas públicas que visam à sustentabilidade da captura da lagosta na região.