Two hundred years after a commercial marine turtle fishery: the current status of marine turtles nesting in the Cayman Islands

AbstractLarge populations of marine turtles breeding in the Cayman Islands were drastically reduced in the early 1800s. However, marine turtle nesting still occurs in the islands. The present-day status of this nesting population provides insight into the conservation of marine turtles, a long-lived species. In 1998 and 1999, the first systematic survey of marine turtle nesting in the Cayman Islands found 38 nests on 22 beaches scattered through the three islands. Three species were found: the green Chelonia mydas, hawksbill Eretmochelys imbricata and loggerhead Caretta caretta turtles. Comparison with other rookeries suggests that the small number of sexually mature adults surviving Cayman's huge perturbations may be impeding population recovery. This shows the need to implement conservation measures prior to massive reductions in population size.

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Placing Madagascar's marine turtle populations in a regional context using community-based monitoring

Oryx ◽

10.1017/s0030605315001398 ◽

2016 ◽

Vol 51 (3) ◽

pp. 542-553 ◽

Cited By ~ 4

Author(s):

Frances Humber ◽

Brendan J. Godley ◽

Tanguy Nicolas ◽

Olivier Raynaud ◽

Florence Pichon ◽

...

Keyword(s):

Western Indian Ocean ◽

Marine Turtle ◽

Current Status ◽

The West ◽

Community Based ◽

Building Capacity ◽

Marine Turtles ◽

Nesting Sites ◽

The Status ◽

Nesting Aggregation

AbstractMadagascar is an important foraging ground for marine turtles in the Western Indian Ocean, yet the status of the country's nesting aggregations remains poorly documented. We assess the current status and trend in nesting throughout Madagascar, including data recorded by a community-based monitoring project in the Barren Isles (western Madagascar). We contextualize the findings in comparison with data from Madagascar's closest neighbouring states. Reports indicate that nesting levels have declined at many coastal sites, with no known recordings since 2000 at > 40 nesting sites. We estimate there are a minimum of 1,200 nests per year in Madagascar, with the largest recorded nesting aggregation (< 1,000 nests per year) found on islands off the west and northern coasts. The majority of nesting aggregations, including those recorded by the community-based monitoring project in the Barren Isles, are relatively small, in the order of < 50 nests per year, yet they are potentially important sources of regional genetic diversity. Nesting on many of the islands (e.g. Tromelin, Europa) around Madagascar has increased over the last 20 years, despite the fact that thousands of turtles probably originating from these sites are taken by fishers in the waters of Madagascar annually. We discuss the importance of protecting small nesting populations, and how community-based monitoring could be an important tool for conserving remote and vulnerable populations and building capacity for natural resource management.

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Plastic ingestion by freshwater turtles: a review and call to action

Scientific Reports ◽

10.1038/s41598-021-84846-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Adam G. Clause ◽

Aaron J. Celestian ◽

Gregory B. Pauly

Keyword(s):

Marine Species ◽

Marine Turtle ◽

Freshwater Turtle ◽

Freshwater Turtles ◽

Plastic Pollution ◽

Potential Threat ◽

Implementation Quality ◽

Turtle Species ◽

Marine Turtles ◽

Conservation Concern

AbstractPlastic pollution, and especially plastic ingestion by animals, is a serious global issue. This problem is well documented in marine systems, but it is relatively understudied in freshwater systems. For turtles, it is unknown how plastic ingestion compares between marine and non-marine species. We review the relevant turtle dietary literature, and find that plastic ingestion is reported for all 7 marine turtle species, but only 5 of 352 non-marine turtle species. In the last 10 years, despite marine turtles representing just 2% of all turtle species, almost 50% of relevant turtle dietary studies involved only marine turtles. These results suggest that the potential threat of plastic ingestion is poorly studied in non-marine turtles. We also examine plastic ingestion frequency in a freshwater turtle population, finding that 7.7% of 65 turtles had ingested plastic. However, plastic-resembling organic material would have inflated our frequency results up to 40% higher were it not for verification using Raman spectroscopy. Additionally, we showcase how non-native turtles can be used as a proxy for understanding the potential for plastic ingestion by co-occurring native turtles of conservation concern. We conclude with recommendations for how scientists studying non-marine turtles can improve the implementation, quality, and discoverability of plastic ingestion research.

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Status of Marine Turtles in British Columbia Waters: A Reassessment

The Canadian Field-Naturalist ◽

10.22621/cfn.v118i1.885 ◽

2004 ◽

Vol 118 (1) ◽

pp. 72 ◽

Cited By ~ 3

Author(s):

Donald F. McAlpine ◽

Stan A. Orchard ◽

Kelly A. Sendall ◽

Rod Palm

Keyword(s):

British Columbia ◽

Marine Environment ◽

Chelonia Mydas ◽

Marine Turtle ◽

Dermochelys Coriacea ◽

Concerted Effort ◽

Leatherback Turtles ◽

Marine Turtles ◽

Green Turtles

Marine turtles in British Columbia have previously been considered off course stragglers. Here we document 20 new reports for Green Turtles, Chelonia mydas, and Leatherback Turtles, Dermochelys coriacea, for the province. Until recently there had been no concerted effort to acquire data on marine turtle abundance or frequency off British Columbia. Observations presented here allow a reassessment of marine turtle status in British Columbia waters. We suggest Green Turtles and Leatherbacks should be considered rare vagrants and uncommon seasonal residents, respectively, off British Columbia and that they are a natural part of the British Columbia marine environment.

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Natal foraging philopatry in eastern Pacific hawksbill turtles

Royal Society Open Science ◽

10.1098/rsos.170153 ◽

2017 ◽

Vol 4 (8) ◽

pp. 170153 ◽

Cited By ~ 6

Author(s):

Alexander R. Gaos ◽

Rebecca L. Lewison ◽

Michael P. Jensen ◽

Michael J. Liles ◽

Ana Henriquez ◽

...

Keyword(s):

Genetic Research ◽

Eastern Pacific ◽

Marine Turtle ◽

Natal Philopatry ◽

Eretmochelys Imbricata ◽

Turtle Species ◽

Marine Turtles ◽

Complex Processes ◽

Natal Homing ◽

Hawksbill Turtles

The complex processes involved with animal migration have long been a subject of biological interest, and broad-scale movement patterns of many marine turtle populations still remain unresolved. While it is widely accepted that once marine turtles reach sexual maturity they home to natal areas for nesting or reproduction, the role of philopatry to natal areas during other life stages has received less scrutiny, despite widespread evidence across the taxa. Here we report on genetic research that indicates that juvenile hawksbill turtles ( Eretmochelys imbricata ) in the eastern Pacific Ocean use foraging grounds in the region of their natal beaches, a pattern we term natal foraging philopatry. Our findings confirm that traditional views of natal homing solely for reproduction are incomplete and that many marine turtle species exhibit philopatry to natal areas to forage. Our results have important implications for life-history research and conservation of marine turtles and may extend to other wide-ranging marine vertebrates that demonstrate natal philopatry.

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Late Cretaceous non-marine turtles of Asia: a review of taxonomic diversity and paleobiogeography

10.7287/peerj.preprints.1087 ◽

2015 ◽

Author(s):

Igor Danilov ◽

Ekaterina Obraztsova ◽

Vladimir Sukhanov

Keyword(s):

Late Cretaceous ◽

Environmental Conditions ◽

Geographical Area ◽

Temporal Distribution ◽

Taxonomic Diversity ◽

Coastal Areas ◽

Marine Turtle ◽

Marine Turtles ◽

Middle Asia ◽

Different Ages

Background. This report reviews data on taxonomic diversity and paleobiogeography of Late Cretaceous (K2) non-marine turtles of Asia accumulated since latest reviews in 2000s. K2 non-marine turtles of Asia are known from four main geographical areas: Middle Asia-Kazakhstan (MAK), Mongolia (MO), China (CH) and Japan (JA). Methods. We critically reviewed composition of non-marine turtle assemblages of the K2 for each of the mentioned geographical area to make estimates of taxonomic diversity for different ages of the K2. Based on these data we analyzed temporal distribution of taxa of non-marine turtles and change in taxonomic diversity of turtle assemblages. Results. K2 turtles of MAK are represented by eight suprageneric taxa – Adocidae (Ad), Carettochelyidae (Ca), Lindholmemydidae (Li), Macrobaenidae (Ma), Nanhsiungchelyidae (Na), Trionychidae (Tr), Eucryptodira indet. (Eu), and Testudines indet. (Te), of which Ad, Li, Ma and Tr are known from the Cenomanian(CE) – early Campanian(CA), whereas other taxa only from the CE-early Turonian(TU). Taxonomic diversity changes from 10–12 species and genera, 6–8 suprageneric taxa in the CE to 7 species and genera, 4 families in the late TU early CA. K2 turtles of MO are represented by seven suprageneric taxa – Ad, Ca, Li, Ma, Meiolaniformes (Me), Na, and Tr, of which Li, Na and Tr are known from the CE-Maastrichtian(MA), Ad, Ca, and Ma, from the CE-Santonian(SA), and Me, only from the MA. Taxonomic diversity changes from 12 species, 10 genera, 6 families in the CE – SA, 8–9 species, 7–9 genera, 3 families in the CA, and 9 species, 7–8 genera, and 4 suprageneric taxa in the MA. K2 turtles of CH are represented by three suprageneric taxa (Li, Na, and Tr), but their precise temporal distribution is poorly known. Taxonomic diversity in the K2 is 12 species, 11–12 genera, and 3 families. K2 turtles of JA are represented by six suprageneric taxa (Ad, Ca, Na, Tr, Eu, and Te), of which Na are known from the CE-SA, Tr from the Coniacian(CO)-CA, and other taxa from the CO-SA. Taxonomic diversity changes from 1 species, genus, and family in the CE-TU to 7 species and genera, and 5–6 suprageneric taxa in the CO-SA. Discussion. In MAK, most significant transformation of turtle assemblages occurred in the CE-TU, whereas transformation in the SA-CA was less significant. On the contrary, in MO, most significant transformation occurred in the SA-CA, and less significant in the CA-MA.The patterns of transformation of the K2 turtle assemblages of CH and JA are not clear. The differences in the patterns of diversity and transformations of the K2 turtle assemblages in different geographical areas of Asia may be explained by different environmental conditions in these areas at that time and influence of such factors as transgressions in coastal areas (MAK and JA) and cooling and aridizations in inland areas (MO and CH).

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Evidence-based management to regulate the impact of tourism at a key marine turtle rookery on Zakynthos Island, Greece

Oryx ◽

10.1017/s0030605312000385 ◽

2013 ◽

Vol 47 (4) ◽

pp. 584-594 ◽

Cited By ~ 29

Author(s):

Kostas A. Katselidis ◽

Gail Schofield ◽

Giorgos Stamou ◽

Panayotis Dimopoulos ◽

John D. Pantis

Keyword(s):

Sea Level ◽

Marine Turtle ◽

Evidence Based ◽

Marine Turtles ◽

Nest Placement ◽

Conservation Effort ◽

Natural Nest ◽

The Impact ◽

Scientific Tool ◽

Beach Use

AbstractThis study evaluates how key beach features influence suitability for nesting by Endangered loggerhead marine turtles Caretta caretta at an internationally important rookery on Zakynthos Island, Greece. During 2007–2009 we assimilated information on beach structure (elevation above sea level and width), the distribution of all nesting (turtle tracks that resulted in nests) and non-nesting (turtle tracks that did not result in nests) turtle emergences from the sea along 6 km of beach, nest placement parameters (distance from sea and elevation above sea level), and beach use by visitors. We found that turtles preferentially emerged on steeper sections of beach, with higher nesting densities occurring on the most environmentally stable beaches. Elevation was a more reliable indicator of nest placement (1 m above sea level) than distance to shore. However, because nests on steeper slopes are located closer to shore, the risk of damage by tourism is increased in such areas. We calculated a potential 36% overlap of natural nest locations with use of the beach by tourists; however, the recorded overlap was 7% because of existing management protocols. This overlap could be further reduced by focusing conservation effort (i.e. further restricting use by people) on beach sections with the steepest inclines. For example, slopes of > 22° comprise 1 km of total beach area annually, the closure of which (above the immediate shoreline to allow passage) would completely protect 50% of nests. This study shows the value of evidence-based management as a practical scientific tool to conserve threatened species in dynamic protected areas that are of both environmental and economic importance.

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A Global Analysis of Anthropogenic Development of Marine Turtle Nesting Beaches

Remote Sensing ◽

10.3390/rs12091492 ◽

2020 ◽

Vol 12 (9) ◽

pp. 1492

Author(s):

Sarah J. Biddiscombe ◽

Elliott A. Smith ◽

Lucy A. Hawkes

Keyword(s):

Global Analysis ◽

Earth Satellite ◽

Google Earth ◽

Coastal Development ◽

Marine Turtle ◽

Intergovernmental Panel ◽

Sea Levels ◽

Marine Turtles ◽

Coastal Squeeze ◽

Nesting Beaches

The Intergovernmental Panel on Climate Change predicts that sea levels will rise by up to 0.82 m in the next 100 years. In natural systems, coastlines would migrate landwards, but because most of the world’s human population occupies the coast, anthropogenic structures (such as sea walls or buildings) have been constructed to defend the shore and prevent loss of property. This can result in a net reduction in beach area, a phenomenon known as “coastal squeeze”, which will reduce beach availability for species such as marine turtles. As of yet, no global assessment of potential future coastal squeeze risk at marine turtle nesting beaches has been conducted. We used Google Earth satellite imagery to enumerate the proportion of beaches over the global nesting range of marine turtles that are backed by hard anthropogenic coastal development (HACD). Mediterranean and North American nesting beaches had the most HACD, while the Australian and African beaches had the least. Loggerhead and Kemp’s ridley turtle nesting beaches had the most HACD, and flatback and green turtles the least. Future management approaches should prioritise the conservation of beaches with low HACD to mitigate future coastal squeeze.

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Exploring drivers and deterrents of the illegal consumption and trade of marine turtle products in Cape Verde, and implications for conservation planning

Oryx ◽

10.1017/s0030605316000107 ◽

2016 ◽

Vol 51 (3) ◽

pp. 428-436 ◽

Cited By ~ 5

Author(s):

Joana M. Hancock ◽

Safiro Furtado ◽

Sonia Merino ◽

Brendan J. Godley ◽

Ana Nuno

Keyword(s):

Policy Decision ◽

Cape Verde ◽

Marine Turtle ◽

Marine Turtles ◽

Awareness Campaigns ◽

Key Stakeholders ◽

Apparent Decrease ◽

Illegal Harvesting ◽

Policy Decision Making ◽

Human Predation

AbstractConservation regulations aimed at restricting resource use are commonly used to manage and protect natural resources but their implementation depends on the compliance of resource users. The design of effective regulations should be informed by an understanding of the factors that affect compliance, considering contextual socio-economic information. Changes have been implemented in the national legislation protecting marine turtles in the Cape Verde archipelago, where historical and recent records indicate heavy human predation pressure on nesting and foraging marine turtles. We present an assessment of levels of illegal harvesting and consumption of marine turtle products on two of the islands, Boa Vista and Santiago, and an analysis of their potential drivers. Key stakeholders were interviewed to investigate the perceived impact of the main interventions employed in Cape Verde to reduce illegal harvesting, trade and consumption of marine turtles. Despite an apparent decrease in harvesting and consumption, our results suggest there has been a shift from subsistence harvesting to trade in Boa Vista. The existence of laws to protect marine turtles was perceived as a deterrent to harvesting, and awareness campaigns and a lack of availability were perceived as reasons for the decrease in consumption in Boa Vista and Santiago, respectively. Aiming to inform ongoing discussions, we recommend a multi-targeted approach focusing on both suppliers and consumers to magnify conservation effectiveness. Regular impact evaluation focusing on harvest and consumption is needed to improve the design of regulations and inform policy decision making.

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Defending against disparate marine turtle nest predators: nesting success benefits from eradicating invasive feral swine and caging nests from raccoons

Oryx ◽

10.1017/s0030605314000805 ◽

2014 ◽

Vol 50 (2) ◽

pp. 289-295 ◽

Cited By ~ 18

Author(s):

Richard M. Engeman ◽

David Addison ◽

J.C. Griffin

Keyword(s):

Nest Predation ◽

Sus Scrofa ◽

Nesting Success ◽

Marine Turtle ◽

Financial Cost ◽

Feral Swine ◽

Predator Species ◽

Marine Turtles ◽

Nest Protection ◽

Nesting Season

AbstractNest predation can threaten marine turtle nesting success, and having to address dissimilar predator species complicates nest protection efforts. On Florida's Keewaydin Island predation by raccoons Procyon lotor and invasive feral swine Sus scrofa are disparate, significant threats to marine turtle nests. Using 6 years of nesting data (mostly for loggerhead marine turtles Caretta caretta) we examined the impacts of swine predation on nests and the benefits of swine eradication, caging nests to protect them from raccoon predation, and the effects of nest caging on swine predation. Nest predation by swine began in mid nesting season 2007, after which swine quickly annihilated all remaining marine turtle nests. During 2005–2010 raccoon predation rates for caged nests (0.7–20.4%) were significantly lower than for uncaged nests (5.6–68.8%) in every year except 2009, when little raccoon predation occurred. The proportions of eggs lost from raccoon-predated nests did not differ between caged and uncaged nests. Caging did not prevent destruction by swine but median survival time for caged nests was 11.5 days longer than for uncaged nests, indicating that caged eggs in nests have a greater chance of hatching before being predated by swine. The financial cost of the eradication of swine greatly outweighed the value of hatchlings lost to swine predation in 2007.

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