WWF -

Field report to Belize Marine Program

2009-05-21

A presentation on sea turtles, their nesting behavior, and identification characteristics was given at the WCS research facility on Middle Cay, Glover's Reef Marine Reserve.

The presentation included detailed information on identification of adults, hatchlings, eggs, and tracks of three species of turtles that occur at GRMR. Nesting habitat needs and threats, natural and man-made, were discussed.

Participants included six Fisheries Department staff, including the Managers of Bacalar Chico Marine Reserve, South Water Caye Marine Reserve, and GRMR, as well as a biologist and two rangers from the GRMR.

In addition, two land owners of GRMR cayes attended, and three WCS/Belize staff.

After the presentation, we visited Long Caye and Northeast Caye and discussed nesting habitat condition and artificial lighting. Handouts on species identification characteristics and artificial beach lighting were provided.

Hawksbill sea turtles: can phylogenetics inform harvesting?

2009-05-19

In their recent articles, Mortimer et al. (2007) and Bowen et al. (2007) imply that historical declines in hawksbill sea turtle (Eretmochelys imbricata) populations in the Caribbean together with new phylogenetic data provide solid evidence that hawksbills cannot be harvested on a sustainable level.

We suggest that broad inferences on the impacts of harvesting based on phylogenetic data alone are insufficient as an argument against sustainable use of sea turtles.

Rather, we recommend that the merits of harvesting schemes should be assessed on a case-by-case basis, which should enable beneficial and sustainable projects to proceed and also discourage unsustainable ones.

Extensive hybridization in hawksbill turtles nesting in Brazil

2009-05-19

Bahia state hosts over 90% of hawksbill (Eretmochelys imbricata) nests registered in the main nesting sites monitored by Projeto Tamar-IBAMA in Brazil. The genetic diversity of this hawksbill population (n=119) was assayed through the analyses of 752 bp of the mitochondrial DNA control region in nesting females.

Seven distinct haplotypes, defined by 125 polymorphic sites, were found. Most of the individuals (n=67) display four typical hawksbill haplotypes, 50 individuals display two haplotypes characteristic of the loggerhead turtle (Caretta caretta) and two individuals had a haplotype affiliated with the olive ridley (Lepidochelys olivacea). These results demonstrate hybridization between the hawksbills and two species that nest along the Bahia coast. Of special interest is the high occurrence of loggerhead x hawksbill hybrids (42%), which display loggerhead mtDNA haplotypes but are characterized morphologically as hawksbills.

The true hawksbill haplotypes present only three variable sites and low genetic diversity values (h=0.358±0.069; p=0.0005±0.0001). The occurrence of several nesting individuals with identical mtDNA from another species may also suggest a long history of introgression between species producing likely F2 or further generation hybrids. Marine turtle hybrids have been previously reported, but the high frequency observed in Bahia is unprecedented.

Such introgression may influence evolutionary pathways for all three species, or may introduce novel morphotypes that develop apart from the parental species. The presence of a unique hybrid swarm has profound conservation implications and will significantly influence the development and implementation of appropriate management strategies for these species.

Turning the Tide: Exploitation, Trade and Management of Marine Turtles

2009-05-19

This comprehensive review of exploitation, trade and management of marine turtles in the Wider Caribbean Region (WCR) highlights findings related to the legal framework for marine turtle management, patterns of domestic exploitation and use and international trade, and a variety of core management issues, including population monitoring, fishery controls and law enforcement.

While there have been many advancements over the past half-century in our understanding of marine turtle biology and of the management needs of these species, the review concludes that actual management of marine turtles, and of marine turtle exploitation in particular, has in many ways not kept pace with this understanding nor with the contemporary scope of threats to their survival.

The report documents the implications of management shortcomings in one country for the management and conservation efforts being made in others and, finally, calls attention to a range of activities that are being undertaken at the national level to address these problems and which could be expanded or adapted across the region.

Report on the 2007 green turtle program at Tortuguero, Costa Rica

2009-05-19

During 2007, a total of 39 track surveys were conducted along the entire 18 miles of beach between Tortuguero river mouth and Jalova lagoon.

Green turtle nesting was observed between March and November, 2007; although false crawl emergences were seen from mid-February until December. Peak nesting was recorded on 2 September, 2,193 nests were counted in a single night.

An estimated 177,620 green turtle nests were laid during 2007.A total of 21.0% of all green turtle nests recorded during track surveys were deposited between Tortuguero river mouth (mile –3/8) and mile 5, where all night patrols took place.

Jaguars killed a minimum of 12 green turtles in 2007. Hawksbill nesting density was very low throughout the season, with only two nests recorded; one in May, the other in July. During daily track surveys conducted by RAs between 13 June and 31 October, a total of 24,499 green turtle nests and 23,324 green turtle false crawls were recorded between the Tortuguero river mouth and the mile 5 marker.

Whose turtles are they, anyway?

2009-05-15

The hawksbill turtle (Eretmochelys imbricata), listed since 1996 by the IUCN as Critically Endangered and by the Convention on International Trade in Endangered Species (CITES) as an Appendix I species, has been the subject of attention and controversy during the past 10 years due to the efforts of some nations to re-open banned international trade.

The most recent debate has centred on whether it is appropriate for Cuba to harvest hawksbills from shared foraging aggregations within her national waters. In this issue of Molecular Ecology, Bowen et al. have used molecular genetic data to show that such harvests are likely to have deleterious effects on the health of hawksbill populations throughout the Caribbean.

Impacts of coastal development on hawksbill

2009-05-15

The impacts of coastal development on survival and swimming success were investigated for hatchling hawksbill turtles (Eretmochelys imbricata) swimming away from artificially lighted and dark nesting beaches in Barbados. The overall predation rate was 6.9%. Predation rates were not significantly affected by offshore substrate type or beachfront lighting.

However, of those hatchlings leaving lighted beaches that successfully escaped predation, a significantly smaller percentage (32.9%) were able to swim the prescribed distance seawards during the observation period.

Moonlight significantly improved the swimming success of hatchlings leaving lighted beaches, particularly when the moon was full, but also significantly influenced predation rates, which were highest during the full moon (12.6%).

Some hatchlings released from dark beaches were attracted by lights from neighbouring beaches, which only became visible after they were a substantial distance from shore.

Artificial light may override the effects of wave cues in the low wave energy conditions characteristic of leeward Caribbean beaches, making swimming hawksbill hatchlings especially vulnerable to the effects of beachfront lighting.

Ecology of hawksbill turtles (Eretmochelys imbricata) on a western Caribbean foraging ground

2009-05-15

We present results of an inwater research program focusing on basic ecology of juvenile hawksbill turtles (Eretmochelys imbricata) in the Cayman Islands. We made 206 captures of 135 hawksbills in Little Cayman (LC) and 103 captures of 97 hawksbills in Grand Cayman (GC). The Cayman Islands aggregation demonstrated a broad size distribution (20.5–62.6 cm straight carapace length), slow growth rate (3.0 ± 0.9 cm yr−1), and multiple recaptures, suggesting long-term residence in some individuals.

Demonstrated home range was small (mean distance from capture to recapture 545 ± 514 m, range 2–2080 m) although an international tag return suggested a long-range developmental migration. Vertical features provided important habitat in LC, and larger turtles were generally captured in deeper waters. Behavior at sighting varied by habitat: resting, swimming, and feeding were observed in coral reef, reef wall, and hardbottom colonized by sponges and gorgonians, and resting was frequently observed in uncolonized hardbottom.

Images obtained from underwater photographers enhanced understanding of hawksbill foraging behavior: turtles fed on sponges (particularly the leathery barrel sponge, Geodia neptuni), by scraping the reef, and occasionally by consuming thimble jellyfish Linuche unguiculata. Intra- and interspecific interactions were recorded: an apparently commensal feeding relationship was noted with gray Pomacanthus arcuatus, French Pomacanthus paru, and queen angelfish Holacanthus ciliaris and aggressive, possibly territorial, interactions between hawksbills were observed. We also documented causes of injury and mortality in the study area – including legal, illegal and incidental take, vessel collisions, hurricanes, and natural predation.

In-water Surveys of Marine Turtles at Glover's Reef Marine Reserve, September 2007

2009-05-15

The in-water survey team was comprised of up to five WCS staff, six Belize Fisheries staff, and a local resident assisted during one afternoon.

The weather, particularly high wind, and resulting water conditions provided some challenges to the September survey effort.

In addition, some invertebrates that sting/bite and cause irritation to snorkellers were abundant in some areas. Despite these conditions in-water surveys were conducted from 24 – 27 September 2007.

New participants were trained in measuring,weighing, and collecting tissue samples, and for repeat participants methods presented in April 2007 were reinforced.

Diving behavior and movements of juvenile hawksbill turtles (Eretmochelys imbricata) on a Caribbean coral reef

2009-05-15

As historically abundant spongivores, hawksbill turtles (Eretmochelys imbricata) likely played a key ecological role on coral reefs. However, coral reefs are now experiencing global declines and many hawksbill populations are critically reduced. For endangered species, tracking movement has been recognized as fundamental to management.

Since movements in marine vertebrates encompass three dimensions, evaluation of diving behavior and range is required to characterize marine turtle habitat.

In this study, habitat use of hawksbill turtles on a Caribbean coral reef was elucidated by quantifying diel depth utilization and movements in relation to the boundaries of marine protected areas. Time depth recorders (TDRs) and ultrasonic tags were deployed on 21 Cayman Islands hawksbills, ranging in size from 26.4 to 58.4 cm straight carapace length.

Study animals displayed pronounced diel patterns of diurnal activity and nocturnal resting, where diurnal dives were signiWcantly shorter, deeper, and more active. Mean diurnal dive depth (§SD) was 8 § 5 m, range 2–20 m, mean nocturnal dive depth was 5 § 5 m, range 1–14 m, and maximum diurnal dive depth was 43 § 27 m, range 7– 91 m. Larger individuals performed signiWcantly longer dives.

Body mass was signiWcantly correlated with mean dive depth for nocturnal but not diurnal dives. However,maximum diurnal dive depth was signiWcantly correlated with body mass, suggesting partitioning of vertical habitat by size. Thus, variable dive capacity may reduce intraspeciWc competition and provide resistance to degradation in shallow habitats.

Larger hawksbills may also represent important predators on deep reefs, creating a broad ecological footprint over a range of depths.

Increase in hawksbill sea turtle nesting in Barbados, West Indies

2009-05-15

Nesting by hawksbill sea turtles (Eretmochelys imbricata) in Barbados, West Indies, has been monitored since 1992. Data from the index beach indicate that the number of nests may have increased as much as 8-fold over this period.

The estimated abundance of nesting females on Barbados is 1250, suggesting that this eastern Caribbean island now hosts one of the largest rookeries in the wider Caribbean, with over 230 females nesting on the index beach alone. Given its extreme easterly position and the prevailing north-westerly current flow into the Caribbean Sea, Barbados is likely to be a significant contributor to foraging grounds throughout the region.

Primary females,which are untagged and without tag scars, made up the majority of females encountered on nesting beaches in most years, suggesting that reductions in juvenile and sub-adult mortality, both nationally and regionally, are significant to the increase in number of nesting females.

Females nest every 2.47 yr on average, although remigration intervals of individual females vary (range: 1 to 6 yr), suggesting environmental influences on nesting periodicity.

The average clutch frequency estimated from the index beach was 4.1 nests per female, but that calculated from less intensively surveyed beaches was lower. Primary and Remigrant females differed in length, mass and clutch frequency; the results must be viewed with caution, however, as preliminary laparoscopic examinations revealed that some Primary females were not in fact nesting for their first season, and because differences in nest site fidelity between the 2 groups of females could potentially cause the differences in clutch frequencies estimated.

An Assessment of the Status and Exploitation of Marine Turtles in Anguilla

2009-05-13

At least three species of marine turtle (leatherback, green and hawksbill turtles) nest in Anguilla, but in critically low numbers and much needs to be done to ensure the continued existence of the nesting populations and facilitate their recovery.

Foraging marine turtles (generally green and hawksbill turtles) are widespread in Anguillian coastal waters and appear to be locally abundant at some sites.

Until 1995, there was a turtle fishery in Anguilla and, from information gathered through the TCOT Socio-Economic Questionnaire, it appears that thousands of green turtles and hundreds of hawksbill turtles were caught each year. The 5-year moratorium on turtle fishing introduced in 1995 was extended for a further 5 years in 2000.

To date, there has been no consistent monitoring of marine turtle populations, but there is a general perception amongst the local population that the number of turtles in Anguillian waters is on the increase. By all accounts, direct exploitation has been drastically reduced by the moratorium with only occasional take for personal use.

An Assessment of the Status and Exploitation of Marine Turtles in Bermuda

2009-05-13

The nesting marine turtle populations that once used the beaches of Bermuda are now extinct. Currently, large numbers of juvenile green turtles are found in Bermuda's waters along with a smaller number of hawksbill turtles.

Loggerheads and leatherbacks rarely visit Bermuda's waters. There are historical records of Kemp's ridleys from Bermuda, but none have been encountered in recent memory.

A long-term green turtle monitoring project has been in operation in Bermuda for over 30 years and has produced valuable data on population structure, migrations, genetic identity and habitat use. Methodological variance over the three decades hinders interpretation of trend data on marine turtle abundance.

Limited data regarding the perceptions of fishers and others subject to the TCOT socioeconomic questionnaire suggest that, although most species are generally perceived to have decreased in the long term, in the last 5 years the green turtle populations are generally perceived to have increased.

Although formerly the site of a marine turtle fishery, turtles are no longer subject to direct harvest in Bermuda, although boat strikes, fatalities due to marine debris, incidental capture in marine fisheries and loss of sea grass habitat are considered threats to Bermuda's sea turtles worthy of further investigation.

Monitoring and conservation of critically reduced marine turtle nesting populations

2009-04-24

Historically, nesting marine turtles were abundant in the Cayman Islands and were an integral part of the economy and culture. Today, nesting of loggerhead turtle (Caretta caretta) and green turtles (Chelonia mydas) takes place at very low levels.

Hawksbill (Eretmochelys imbricata) nesting has not been recorded since 1999. We overview highly detailed monitoring data gathered over a 6-year period allowing insight into the magnitude and spatial and temporal patterns of marine turtle nesting, cost-effectiveness of monitoring such reduced populations, impacts of development on reproductive success and current threats to the recovery of the population.

Nesting is diffuse and widely distributed for both nesting species on Grand and Little Cayman. Modelled nesting detection profiles for Grand Cayman show that in order to maintain data resolution, most sandy coastline must be surveyed throughout each season.

However, in Little Cayman it may be possible to reduce effort. Legal take of adults and illegal take of eggs may be significantly impacting the remaining population. Surprisingly, we observed no significant
correlation between density of coastal development and clutch density, adult emergence success or hatching success for either species.

A significant relationship exists however, between density of coastal development and incidence of misorientation events in loggerhead hatchlings but not in green turtle hatchlings. Effective protection of known nesting habitat and the elimination of exploitation of remaining adults and eggs within the population are critical to its recovery.

Tortuga carey del Caribe; biología, distribución y estado de conservación.

2009-02-02

Este texto se basa en los documentos generados entre el 2001 y el 2002 por el Grupo de Especialistas en Tortugas Marinas de la Unión Internacional para la Conservación de la Naturaleza durante el proceso de diálogo de la tortuga carey del Caribe gestado por CITES (Convención sobre el comercio internacional de especies amenazadas de fauna y flora silvestre), específicamente los trabajos de Frazier, J. y Meylan, A.
Por otro lado, se utilizan una variedad de documentos que anteriormente se produjeron y que analizaron temáticas asociadas a esta especie, tales como Groombridge y Luxmoore (1989) para la Secretaría de la CITES. En 1999, la revista Chelonian Conservation and Biology dedicó un volumen al examen de esta especie, incluyendo la "Justificación del estado de enlistado como especie críticamente en peligro de la tortuga carey (Eretmochelys imbricata) en 1996 según la lista roja
de la UICN para animales amenazados" por Meylan y Donnelly y "El estado de la tortuga carey (Eretmochelys imbricata) en la región del Caribe" por Meylan.

Migration of hawksbill turtles from Tortuguero, Costa Rica

2006-11-07

The hawksbill turtle (Eretmochelys imbricata) is a widely distributed and critically endangered species that feeds on sponges and fills an important ecological role in the coral reef ecosystem. At Tortuguero, Costa Rica, trend analyses indicate considerable decline in nesting estimated at 77.2% - 94.5% between 1956 and 2003, as a result of excessive turtle fishing.

Hawksbill Turtles of Barbados

2006-01-01

Hawksbills have long been harvested for their shell, meat and eggs resulting in populations that are severely depleted globally. Barbados has one of the largest hawksbill nesting populations in the insular Caribbean. Shy and secretive, hawksbills emerge under the cover of darkness to make their nests, preferring the narrow, relatively steeply sloping coral sand beaches that typify the leeward coasts of tropical islands like Barbados.

Sea turtles are amongst the most fascinating of species. Marine, but dependent on the land to reproduce; they may spend decades migrating over vast areas of ocean, before homing back to the beach they were born on to lay their own eggs.

Witnessing the emergence from the sea of one of these mysterious creatures or watching hatchlings disappearing into the waves are unforgettable experiences, experiences that continue to thrill and amaze even after years of working with them. Largely due to the efforts of the Barbados Sea Turtle Project, the hawksbill is now protected from harvest in Barbados. However, much remains to be done to ensure their recovery.

Rumbo a la COP 3

2005-03-01

International Movements of Immature and Adult Hawksbill Turtles in the Caribbean Region

2005-01-01

International movements of 19 adult and 9 immature hawksbills in the Caribbean region are summarized. Adult hawksbills traveled minimum distances of 110–1936 km, immatures traveled 46–900 km. These data and results of molecular genetic studies in the Caribbean refute the hypothesis that hawksbills are non-migratory. Compared with other marine turtle species, relatively few hawksbills have been tagged - an approximate cumulative total of 2500 individuals at the major nesting sites in the Caribbean during the last 40 years.

International recapture rates of adult female hawksbills tagged on the nesting beach are on the order of 0–3.5%, which is comparable to those of other species of marine turtles that are considered to be highly migratory. High rates of local recapture of immatures on feeding grounds suggest long-term residency in developmental habitats. Knowledge of the schedules and routes of migrations is crucial to the effective management of hawksbills on both regional and multinational levels.

A Map - Based Indicator of Threats to the World's Coral Reefs

2005-01-01

Until half a century ago, the worst threats to coral reefs were storms, volcanic eruptions, periodic ice ages, and occasional comets striking the Earth. However, since the 1950s, and at an accelerating pace, humankind has added significant new pressures ranging from outright mining of coral for building materials, widespread pollution, and destructive fishing practices to loss of vital related mangrove and seagrass ecosystems.

Concern has been growing for decades about the fate of coral reefs, especially in recent years as more and more people have access to these underwater worlds and have come to realize their value for reasons that both embrace and transcend aesthetic, scientific, economic, and environmental considerations. Many more who have not seen these notorious "rainforests of the sea" for themselves have been made aware of their importance and are motivated to want to do something to stay their swift loss. In 1997, which the United Nations declared as the "International Year of the Reef," many questions were raised about just how widespread the problems are and what can be done to help protect what remains of healthy systems - and restore those that are damaged.

Although coral reefs have become the subject of thousands of research projects in the past few years, remarkably little has been done to attempt a global assessment of where and what are the most pressing problems.