Table of Contents
Overview
Distribution
Range Description
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Geographic Range
The Central American river turtle, Dermatemys mawii, can be found in Central America from southern Mexico as far south as northern and eastern central Guatemala, excluding the Yucatan Peninsula. There have also been sightings of D. mawii reported in northern Honduras (Ernst and Barbour 1989; Pritchard 1979).
Biogeographic Regions: neotropical (Native )
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Distribution: Mexico (C/S Veracruz, Tabasco, N Chiapas, S Campeche, S Quintana Roo, but absent from most of the Yucatan Peninsula), N Guatemala, Belize, (Tetela, Oaxaca ?), NW Honduras (Pough et al. 1998).
Type locality: "South America" (in error); restricted to "Alvarado, Veracruz," Mexico, by Smith and Taylor 1950: 346.
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Mexico, Belize, Guatemala
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Physical Description
Morphology
Physical Description
In adulthood, D. mawii can grow to be quite big. At its largest, this animal can measure up to 65 cm in length and it can weigh approximately 20 kg.
The smooth, somewhat flattened carapace, the top portion of the shell, has a uniform olive-gray color and is only slightly domed. The underside, or plastron, is cream-colored, rounded at the front and serrated at the end. In adults, the carapace lacks a well-defined vertebral ridge running down its center and is smooth and unnotched around the outer edge. In juveniles of the species, this ridge is present as well as a notched posterior shell end that is somewhat outspread. Additionally, juveniles have a carapace that is browner in color and a keel, which is absent in adults. In addition to being smooth, the shell is quite thick and rather heavy. The bones that make up the shell can become so tightly fused together in older adults that the sutures, the structures that join the bones of the shell together, become almost invisible, even in dry, bony shells.
The head of D. mawii is rather small, its skull lacking several features present in most turtles. The turtle's slightly upturned nose is large, and shaped like a tube with wide nostrils. It is a rather prominent feature of the turtle's face because it projects rather strongly from the front of the head.
The majority of the fleshy parts of the Central American River Turtle are olive gray, the undersides being white or pale gray. Near its upper surface, the organism is reddish brown to yellow in color while its sides typically remain the olive-gray of the shell. Adult male turtles have a triangular patch covering the whole upper section of the head that is golden yellow in color, as well as yellow markings on each side of the head. Females and turtles that have not yet reached maturity, have dull patches and side markings that are barely visible. Juveniles, however, display a yellow stripe extending backwards from the eye. The tail of D. mawii is thick and longer in males than in females. It extends past the edge of the back of the carapace in males and just barely to that edge in females.
Incredibly thin and almost membrane-like, the turtle's scutes, keratin coverings over the bones that make up the shell, are very sensitive and prone to abbrasions when in contact with hard surfaces. If, for example, the animal comes in contact with concrete, it will only be a short time before the animal has almost worn itself away to the bone. While the damage that can be done will be repaired to some extent, it will never completely heal and become smooth again, as it once was. Sheets of dead bone will be shed to reveal a pitted, but healed surface. The scute boundaries, like the sutures, become virtually invisible in adults.
The legs of D. mawii are dark gray with no patterns. The feet are fully webbed and broad, each with large scales on the outside edges (Dawson 1998; Ernst and Barbour 1989; Konstant 2000; Pritchard 1979).
Range mass: 0 to 0 kg.
Average mass: 20 kg.
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Ecology
Habitat
Habitat and Ecology
Females reach maturity between 34.2–42.0 cm, while males become mature between 32.8-38.5 cm (Polisar 1996, Vogt unpublished data). Females grow larger than males; largest size reported is 60 cm and 22 kg (Alvarez del Toro et al. 1979), although none of 567 turtles examined by Polisar (1996) in North-Central Belize during 1989–1990 exceeded 49 cm. No information is available on age at maturity or on longevity.
Nesting begins during the height of the rainy season from September through December when water levels are at their annual peaks; up to three, exceptionally four, clutches of eggs are laid (Vogt and Flores-Vilela 1992, Polisar 1996). Reports in the literature describing the nesting season as March and April (Lee 1969, Moll 1986a) were based on turtles found in the markets that were most likely holding their eggs for an extended period due to their captive condition. Some females may lay their ultimate clutch for the season in late February or early March, but these are anomalies. Vitellogenesis begins in June and July with oviposition from September to March in the Rio Lacantun in Chiapas (Vogt unpublished data).
Nests are excavated within 3 m of the shoreline, usually within 1 m (Alvarez del Toro et al. 1979), often in saturated soil. Nests are often constructed under an overhanging river bank. Since the nests are scattered along a dynamic shoreline during the rainy season they often go undetected by predators. Often nests are exposed by flood waters creating the misconception that this species of turtle lays its eggs underwater (Vogt unpublished data). The earliest nests of the season are often inundated for weeks at a time with no effect on survivorship. Polisar (1992) documented 80–100% hatching success in eggs subjected to more than 30 days of submersion in water. The physiological mechanisms of this emybryonic diapause need to be investigated further.
Up to three clutches were laid per year in Chiapas, with clutch size ranging from 6-16 eggs. Incubation time in the laboratory varied from 115–223 days, this variation is attributed to embryonic dormancy. Diapause allows the eggs to remain at an early developmental stage when environmental conditions are not favorable for development, cool temperatures and flood conditions, diapause is broken by drying of the nests and warmer temperatures. Clutches laid over a 4 month time span hatch synchronously, stimulated by moistening of the soil during the first summer rains (Vogt unpublished data). In Belize Polisar (1992) reported 217–300 days between oviposition and hatchling emergence. Vogt and Flores-Villela (1992) reported that incubation temperatures in the laboratory above 28° C produced all females and temperatures of 25–26° C produced males.
Systems
- Terrestrial
- Freshwater
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Habitat
As long as there is an abundant food supply, D. mawii is not very particular about the environment it lives in. Individuals can inhabit just about any freshwater aquatic environment within their range, from deep, clean water bodies to muddy backwaters, oxbows, and temporary seasonal pools. Primarily, however, they live in large lagoons, lakes and rivers.
The presence of barnacles on the shells of some individuals indicates that salty environments do not pose a problem for this species of turtle and may show that D. mawii spends time in tidal areas near the mouths of large rivers (Ernst and Barbour 1989).
Aquatic Biomes: lakes and ponds; rivers and streams
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Trophic Strategy
Food Habits
The Central American River Turtle generally eats plants either submerged below the water or those that rise just above the water's surface. Typically, these include Russell river grass (Paspalum paniculatum), and fallen leaves and fruits from branches growing over the water.
Captured D. mawii will occasionally, however, eat fish. Juveniles in captivity tend to more readily accept animal matter as food which may show that young D. mawii are more apt to be carnivorous (Ernst and Barbour 1989; Konstant 2000; Poaceae 2000).
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Life History and Behavior
Life Expectancy
Lifespan/Longevity
Average lifespan
Status: captivity: 8.1 years.
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Lifespan, longevity, and ageing
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Reproduction
Reproduction
Nesting occurs continuously from September to November during the time when the rivers the turtles live in swell considerably due to flooding caused by seasonally increased rainfall. This phenomenon helps D. mawii reproduce because it allows females to lay eggs in more secluded areas away from the normal river channel. Normally, females could not reach these areas by foot but because they are flooded with the excess rainwater, they are easy to swim to.
Once females have reached a shallow rivulet, they dig out a nest, lay their eggs, and bury them at the edge of the water under mud and decaying vegetation.
Generally, D. mawii lays oblong eggs with white shells that are very thick and hard. Each clutch contains six to twenty eggs that are approximately 57-70 mm long and 30-34 mm wide.
Because the life of this turtle is so completely aquatic (and therefore difficult to study), little else is known about its development and early life (Ernst and Barbour 1989; Pritchard 1979).
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Molecular Biology and Genetics
Molecular Biology
Statistics of barcoding coverage: Dermatemys mawii
Public Records: 0
Species: 1
Species With Barcodes: 1
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Conservation
Conservation Status
IUCN Red List Assessment
Red List Category
Red List Criteria
Version
Year Assessed
Assessor/s
Reviewer/s
Contributor/s
Justification
History
- 1996Endangered
- 1994Vulnerable(Groombridge 1994)
- 1990Vulnerable(IUCN 1990)
- 1988Vulnerable(IUCN Conservation Monitoring Centre 1988)
- 1986Vulnerable(IUCN Conservation Monitoring Centre 1986)
- 1982Vulnerable
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Conservation Status
Because the meat of D. mawii is sold at markets near rivers for high prices, the turtles are highly sought after and have been over-exploited by hunters. The hunting problem is exacerbated by the fact that these turtles are easy to catch because of their passive nature. Legislation has been passed nationally and internationally to help D. mawii but enforcement of this legislation remains inadequate (Ernst and Barbour 1989; Konstant 2000; Pritchard 1979).
US Federal List: no special status
CITES: appendix ii
IUCN Red List of Threatened Species: critically endangered
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Status: Endangered
Date Listed: 06/22/1983
Lead Region: Foreign (Region 10)
Where Listed:
Population detail:
Population location: entire
Listing status: E
For most current information and documents related to the conservation status and management of Dermatemys mawii , see its USFWS Species Profile
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Trends
Population
Populations of Dermatemys are now so low in Mexico that recovery is perhaps not possible in most regions. The only viable populations of Dermatemys currently (in 2005) exist in inaccessible areas far from civilization. In the Rio Blanco of Veracruz there exists a recuperating population, with a proportion of subadults to adults that is extremely high. Normally at least 80 per cent of the population consists of adults when the population is not being over harvested (Vogt unpublished data). When there are few adults and few subadults and more hatchlings found than adults the population is in extremely fragile shape. When this population was trapped in the late 1990s it had a majority (80%) of subadults, signifying that the adults had recently been overharvested, but that there was sufficient reproductive stock being produced that the population was judged to be recuperating. How many decades this might take is unknown (Vogt unpublished data).
Dermatemys is legally protected by several laws and international agreements but these regulations have not stopped its capture or consumption, and populations of the species in Mexico have been almost eliminated (Vogt and Flores Villela 1992). In Guatemala the status of the population is not clear (Polisar and Horwich 1994). Moll (1986b) conducted countrywide surveys of river systems inhabited by Dermatemys, and market surveys, in 1983–1984. Polisar (1992) documented population structures in sections of the Belize River exposed to contrasting levels of exploitation, finding adults very scarce in the heavily exploited sections. There are reasonable probabilities that some populations in Belize are now afforded at least partial protection, such as sections of Rio Bravo and Irish Creek, Cox Lagoon, and part of the Sibun River (which is a village-originated Hickatee Conservation Area). While pressures in Belize can be assumed to be high, trends have been less disastrous and declines less rapid than in Mexico.
In Guatemala the status of the populations are not known (Polisar and Horwich 1994). A herpetofauna survey of Laguna del Tigre, Peten, Guatemala, in April 1999 focused on Morelet's Crocodile but also recorded the occurrence of Dermatemys, though in densities too low to quantify reliably (Castañeda Moya et al. 2000). Further surveys in Guatemala and follow-up evaluations in Belize are a priority.
It was listed in the 1982 IUCN Amphibia-Reptilia Red Data Book as Vulnerable (Groombridge 1982) and has been considered as a high priority by the IUCN Tortoise & Freshwater Turtle SG in its 1989 action plan; it was uplisted to Endangered in the 1996 IUCN Red List.
Population Trend
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Threats
Threats
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Management
Conservation Actions
In Belize, there is national legislation (Statutory Instrument No. 55, of April 1993) designed to control the level of harvest and establish some protected populations (Polisar 1994). The efficacy of this legislation needs to be evaluated and the nation-wide status of the species assessed.
Dermatemys is protected under Guatamalan law (Campbell 1998) but exact details are not available.
D. mawii is categorized as a highly protected species under the U.S. Endangered Species Act (Code of Federal Regulations, 1987).
Dermatemys is listed on Appendix II of CITES.
Laguna La Popotera, Veracruz, Mexico, was designated a RAMSAR site in 2005 with specific hopes of creating the first extensively managed wildlife reserve specifically for Dermatemys (Horne in litt. to TFTSG RLA, 27Jul 05). The species is present in Laguna del Tigre N.P. in Peten, Guatemala, and was recommended as a focal species for park management (Castañeda Moya et al. 2000).
Currently there are several ex situ populations of this species with which viable breeding colonies can be established in different zoos and farms. Some of these ex situ populations are: Nacajuca, Tabasco, with 880 turtles, La Florida, Veracruz, with 45 turtles, the Veracruz Aquarium with 2 animals, Chicago Zoo with 2 animals, Detroit Zoo with 2 animals, Philadelphia Zoo with 9 specimens, and the Guatemala City Zoo with one animal.
In 2004 a group for D. mawii conservation was established, proposing a program that includes raising the authorities' and people’s awareness on the species, its captive conservation that includes the genetic management of the captive populations, evaluating the wild populations and their habitat, improved enforcement of existing legal protection, promotion of harvest management measures for sustainable use, and the creation of a reintroduction program.
In summary, existing protective measures need to be implemented, populations inhabiting protected areas must be watched over carefully, and careful thought must be given to meeting some, if not all, of the intensive commercial demand for the species by sustainable production from farms.
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Relevance to Humans and Ecosystems
Benefits
Economic Importance for Humans: Negative
There are no known adverse effects of this species on humans.
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Economic Importance for Humans: Positive
The flesh of D. mawii is a high quality food source that can be obtained in high quantity from one turtle. Central American River Turtles eat aquatic plants that are of no use to humans and use them to produce turtle protein for human consumption. Not only could Central American River Turtles supply a valuable protein source if farmed successfully, they could also supply a valuable source of income for humans living near their habitat (Ernst and Barbour 1989).
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Wikipedia
Central American river turtle
 | This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (June 2008) |
The Central American river turtle or Mesoamerican river turtle (Dermatemys mawii) locally known as the "hickatee" or "tortuga blanca"-(white turtle) is the only living species in the family Dermatemydidae. Its closest relatives are only known from fossils
It is a nocturnal, aquatic turtle that lives in larger rivers and lakes in Central America, from southern Mexico to northern Honduras. It is one of the world's most heavily exploited turtles and is classified a Critically Endangered species by the IUCN and is listed as Endangered under the U.S. Endangered Species Act. The Central American river turtle has been intensely harvested, primarily for its meat, but also for its eggs and shell. The turtle has been nearly eliminated from much of its former range in southern Mexico.
Dermatemys species are fairly large turtles, attaining a maximum size of 65 cm (25 inches) in carapace length, and they can weigh in the range of 20 kg (44 lbs).
They have a flattened carapace, that is usually a solid grey or almost black in color. Their plastron is normally cream colored. In juveniles, a distinctive keel is found down the center of the carapace, and the outer edges have serrations. These features are lost as the turtle ages. Its skin is predominantly the same color as the shell, with reddish or peach colored markings around the neck and underside. Males can be differentiated from females by yellow markings on either side of their head, and a longer, thicker tail.
Contents |
Reproduction
Mating and nesting occurs in the fall, from September to November. Females lay clutches of 6–20 eggs on the banks of waterways that they otherwise would not normally be able to reach without the flooding caused by the seasonal rainfall.
Conservation status
Rarely found in captivity, the river turtle has been over-hunted because of its value in the food market. Even the hatchlings and eggs are sold as food. The species' normally passive nature makes them relatively easy to catch. As such, they have been listed as a CITES Appendix II to prevent exportation, and there are local laws in place to prevent them from being hunted.
Conservation efforts in Belize
On 7 December 2010, the first hickatee conservation forum[1] and workshop was held at the University of Belize, Belmopan campus presented by the Turtle Survival Alliance (TSA), in collaboration with the Belize Foundation for Research and Environmental Education (BFREE), the Environmental Research Institute at UB and the Belize Fisheries Department. The purpose of the workshop was to bring together members of the scientific community, government officials, NGO’s and civil society to share information regarding the critically endangered hicatee turtle (Dermatemys mawaii).
The Turtle Survival Alliance is an international conservation partnership that is committed to zero turtle extinctions. Focusing on species ranked critically endangered, the TSA supports projects or programs around the world with an emphasis on Madagascar and Asia. The mission of the TSA is: Transforming passion for turtles into effective conservation action through a global network of living collections and recovery programs. An important aspect of the meeting was to share the results of a recent country-wide survey of Hickatee and that was conducted in April–May of this year and was supported by TSA in conjunction with local NGO’s, and civil society under the authority of the Belize Fisheries Department. Results of the survey indicated the population is clearly headed towards extinction in Belize unless conservation measures are put in place. Local population extinctions have been documented, and current harvesting rates have been determined to be unsustainable. When compared to previous surveys, the most recent survey indicates that overall populations of Hicatee continue to decline across the nation.
Captive turtle breeding program in Belize
A study, managed by the Turtle Survival Alliance (TSA) and conducted on Belize Foundation for Research and Environmental Education (BFREE) property in Belize, began in early 2011 and is a low maintenance operation focused on generating Dermatemys food plants, while exploring husbandry details such as egg laying and incubation. Located in southern Belize along the Bladen River, BFREE encompasses 1,200 acres (4.9 km2) of forest and is situated among four protected areas (Bladen Nature Reserve, Cockscomb Basin Jaguar Reserve,Deep River Forest Reserve and Maya Mountain Forest Reserve), which enhances the possibility of a successful breeding program.
The goal of the program is to generate hatchlings and release them in order to repopulate already depleted wild populations and, ultimately, relieve pressures of local populations. The program has the potential to be expanded once it is determined that the species can be reliably reproduced in good numbers in captivity.
References
- ^ Rainwater, Thomas. "Finishing up the Hicatee Workshops in Belize". Turtle Survival Alliance blog. http://www.turtlesurvival.org/blog/1/129. Retrieved 12 June 2011.
- Vogt et al. (2005). Dermatemys mawii. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 11 May 2006. Database entry includes a range map and justification for why this species is critically endangered
- CITES(2009) Convention on International Trade in Endangered Species of Wild Fauna and Flora
- Ernest, C.H. and R.W. Barbour(1989) Turtles of the World, Smithsonian Institution Press, Washington, DC
- IUCN (2009) International Union for Nature and Natural Resources Red List of Threatened Species. Version 2009.02
- Lee, J.C. The Amphibians and Reptiles of the Yucatán Peninsula. Comstock Publishing Associates, Cornell University Press, Ithaca, New York.
- USFWS (2009) U.S. Fish and Wildlife Service Endangered Species Program
- Polisar, J. (1997) Effects of Exploitation on Dermatemys mawii populations in northern Belize and Conservation Strategies for Rural Riverside Villages. pp. 441–443
- Rainwater, Thomas, Tom Pop, Octavio Cal,Steve Platt and Rick Hudson (2010) "Catalyzing Conservation in Belize for Central America's Imperiled River Turtle," Turtle Survival Alliance Magazine, August 2010, pp. 79–82.
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