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Trichechus manatus ssp. manatus
– Endangered
Taxonomy
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Kingdom:
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ANIMALIA
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Phylum:
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CHORDATA
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Class:
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MAMMALIA
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Order:
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SIRENIA
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Family:
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TRICHECHIDAE
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Scientific Name:
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Trichechus manatus ssp. manatus
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Infra-specific Authority:
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Linnaeus, 1758
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Common Name/s:
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| English | — | ANTILLEAN MANATEE, CARIBBEAN MANATEE |
| French | — | LAMANTIN DES ANTILLES, LAMANTIN DES CARAIBES |
| Spanish | — | MANATI ANTILLIANO |
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Assessment Information
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Red List Category & Criteria:
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EN C1 ver 3.1 (2001)
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Year Assessed:
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2007
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Assessor/s:
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Deutsch, C.J., Self-Sullivan, C. & Mignucci-Giannoni, A.
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Evaluator/s:
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Reynolds J.E., III, Powell, J.A. & the IUCN/SSC Sirenia Specialist Group
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Justification:
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The Antillean manatee subspecies is listed as Endangered because the current population is estimated at less than 2,500 mature individuals and is predicted to undergo a decline of more than 20% over the next two generations (estimated at ~40 years for an unexploited population, based on T. m. latirostris data) without effective conservation actions, due to current and projected future anthropogenic threats (habitat degradation and loss, hunting, accidental fishing-related mortality, pollution, and human disturbance).
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History:
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| 1996 | - | Vulnerable (Baillie and Groombridge 1996) |
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Geographic Range
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Range Description:
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The Antillean Manatee (T. m. manatus) inhabits riverine and coastal systems in the tropical and subtropical Western Atlantic Coastal Zone from the Bahamas to Brazil, including the Caribbean Sea and Gulf of Mexico. Although at least one individual in the Bahamas is a known migrant from Florida (Reid 2000, 2001), the Bahamas is detailed in this T. m. manatus assessment rather than the T. m. latirostris assessment.
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Countries:
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Native:
Bahamas; Belize; Brazil; Cayman Islands; Colombia; Costa Rica; Cuba; Dominican Republic; French Guiana; Guatemala; Guyana; Honduras; Jamaica; Mexico; Netherlands Antilles (Bonaire, Curaçao, Netherlands Leeward Is. - regionally extinct); Nicaragua; Panama; Puerto Rico; Suriname; Trinidad and Tobago; Turks and Caicos Islands; Venezuela; Virgin Islands, British; Virgin Islands, U.S.
Regionally extinct:
Anguilla; Antigua and Barbuda; Aruba; Barbados; Dominica; Grenada; Guadeloupe (Guadeloupe, St. Martin-St. Barthélémy); Martinique; Montserrat; Saint Kitts and Nevis; Saint Lucia; Saint Vincent and the Grenadines
Possibly extinct regionally:
Haiti
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FAO Marine Fishing Areas:
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Native:
Atlantic-southwest; Atlantic-western central
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Population
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Population:
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There are no statistically derived population estimates for T. m. manatus within its range, which historically covers 41 countries in the Wider Caribbean Region. Peer-reviewed publications are sparse, but there has been a significant increase in research on Antillean manatees over the past 10 years, resulting in many theses, presentations at regional meetings, local reports, and adoption of management plans.
We compiled data gathered through an extensive literature review and personal communication with 45 scientists representing expertise in 29 countries, but exclusive of the Florida manatee population (which was assessed independently). Antillean manatee populations occur in 20 of the 37 countries assessed, with sightings of vagrants in additional countries. However, distribution is not continuous and populations are patchy and fragmented. Using these documents, supplemented by the questionnaires completed by local experts, we derived a very rough minimum population estimate for the subspecies. Our confidence in population estimates varies dramatically from country to country, depending on the nature and extent of recent research efforts. For that reason, we used orders of magnitude in an effort to establish some baseline population estimates for each of the 20 countries where populations are most probably extant and viable. Although the quality and quantity of data vary from country to country, there is consistency regarding a continuing decline in both manatees and the quality and quantity of available habitat.
Estimates by country, based on the best available data, range from less than 10 up to ~1,000 total animals, with the largest populations reported from Mexico and Belize (Table 1). No country reports an increasing country-wide population (except Bahamas with less than 10 animals). All publications and personal communications indicate country-wide populations are declining, stable, or unknown. In a few countries, localized populations may be increasing; in most countries, reports indicate a significant decline over the past 30-50 years, but this is based solely on anecdotal evidence and/or interviews with local people.
While the data in Table 1 suggest that approximately 2,600 individuals exist, scattered widely through the Caribbean region, optimistic "estimates" of the size of the manatee population (also based on interviews with experts in different countries, and not necessarily on empirical data) suggest that it may actually be in the range of 5,600 individuals. The age structure of the various manatee subpopulations of T. m. manatus is unknown, but the percentage of mature animals in Florida was estimated to be 70% through population modeling (Haubold et al. 2006) and 46% through carcass recovery (Hernandez et al. 1995, Marmontel 1995, Marmontel et al. 1997). The figure based on carcasses is biased low due to the presence of a large proportion of calves in the sample. We note that hunting and other threats in the Caribbean may lead to a very different age structure for T. m. manatus than for T. m. latirostris; in fact, if hunters target large (i.e., mature) manatees, the percentage of mature individuals for T. m. manatus could be substantially lower than is the case for T. m. latirostris. Therefore, we consider that the percentage of mature individuals for the Antillean subspecies is likely to lie somewhere between 46% and 70%.
Based on the above information, we feel it is likely that the actual population size is intermediate between the number counted (2,600; minimum population size) and the more optimistic suggestions (5,600); an average between those two numbers would place the actual population size at approximately 4,100 manatees. Using this average value, and the two percentages given above for mature animals, the number of mature individuals would therefore lie between 1,886 and 2,870. Selecting the average value between these numbers produces an estimate of 2,378 mature individuals. While we do not place much significance in these average values, it is reasonable to conclude - based on the available evidence and taking the precautionary approach - that the overall number of mature individuals in this subspecies is likely to be less the 2,500.
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Population Trend:
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Habitat and Ecology
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Habitat and Ecology:
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The habitat and ecology of the Antillean manatee is thought to be similar to its sister subspecies. However, given that the Florida manatee inhabits the most northern extent of the species range, behaviour and life history characteristics may be dissimilar in this tropical subspecies. Antillean manatees use rivers, lakes, coastal and inland lagoons, and coastal marine environments, including seagrass, mangrove, and coral reef ecosystems. Although they are able to survive in fresh, estuarine, or marine environments for extended periods of time, several lines of evidence indicate a dependence on periodic access to fresh water for osmoregulation (Ortiz et al. 1998, 1999; Lefebvre et al. 2001; Reid et al. 2003). As herbivores, access to aquatic vegetation is necessary for survival; seagrasses (Thalassia, Halodule, Halophila and Syringodium) appear to be favored in estuarine and marine areas. Osmoregulation and thermoregulation are behaviorally controlled by movements between activity centers. Quiet protected areas are necessary for resting and for cows with young calves; connections (travel corridors) between feeding, drinking, nursery, mating, and resting areas are very important. A discussion of the environmental factors influencing seasonal movements and migratory behavior in both subspecies is provided in Deutsch et al. (2003).
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System:
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Freshwater; Marine
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List of Habitats:
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| 5.1 | Wetlands (inland) - Permanent Rivers/Streams/Creeks (includes waterfalls) |
| 5.2 | Wetlands (inland) - Seasonal/Intermittent/Irregular Rivers/Streams/Creeks |
| 5.5 | Wetlands (inland) - Permanent Freshwater Lakes (over 8ha) |
| 5.6 | Wetlands (inland) - Seasonal/Intermittent Freshwater Lakes (over 8ha) |
| 5.7 | Wetlands (inland) - Permanent Freshwater Marshes/Pools (under 8ha) |
| 5.8 | Wetlands (inland) - Seasonal/Intermittent Freshwater Marshes/Pools (under 8ha) |
| 5.9 | Wetlands (inland) - Freshwater Springs and Oases |
| 9.8 | Marine Neritic - Coral Reef |
| 9.9 | Marine Neritic - Seagrass (Submerged) |
| 9.10 | Marine Neritic - Estuaries |
| 10.1 | Marine Oceanic - Epipelagic (0-200m) |
| 12.5 | Marine Intertidal - Salt Marshes (Emergent Grasses) |
| 13.4 | Marine Coastal/Supratidal - Coastal Brackish/Saline Lagoons/Marine Lakes |
| 13.5 | Marine Coastal/Supratidal - Coastal Freshwater Lakes |
| 15.2 | Artificial/Aquatic - Ponds (below 8ha) |
| 15.3 | Artificial/Aquatic - Aquaculture Ponds |
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Threats
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Threats:
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Major threats to survival of the Antillean manatee include habitat degradation and loss, hunting, incidental catch/accidental take, watercraft collisions, entanglement in fishing gear, pollution, natural disasters, and human disturbance. Although threats due to hunting are diminishing in some areas, all other threats are increasing in most areas. Illegal hunting for subsistence and profit was reported as a significant threat in Brazil, Colombia, Costa Rica, Cuba, Dominican Republic, French Guiana, Guatemala, Honduras, Mexico, Suriname, Trinidad & Tobago, and Venezuela. Pollution from agriculture and mining was consistently noted in reports from South American countries. Intrinsic factors that limit the population’s ability to withstand these anthropogenic impacts include low fecundity, slow growth, limited dispersal, and restricted range.
Of particular note were: (1) In Belize, watercraft related mortality was reported as the major threat, followed by illegal hunting and entanglement in fishing gear; and (2) In north-eastern Brazil, the stranding of live-orphaned calves was identified as the main recent threat to the species (Parente et al. 2004). Between 1981 and 2002, 74 stranded manatees were reported on the north-eastern coast of Brazil with 58% (n=43) being live dependent calves. This high percentage suggested that that the main threat may be human disturbance resulting in mother-calf separation. Disturbance in the area is due to shrimp farms, salt farms, a general increase in human activities in the coastal zone, and uncontrolled tourism. Additional major threats include hunting, entanglement in fishing nets, watercraft collisions, indiscriminate development of the coast, and degradation of aquatic environments.
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List of Threats:
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| 1.1.1.3 | Habitat Loss/Degradation - Agriculture - Crops - Agro-industry farming (present, future) |
| 1.1.6 | Habitat Loss/Degradation - Agriculture - Marine aquaculture (present, future) |
| 1.2.2 | Habitat Loss/Degradation - Land management of non-agricultural areas - Change of management regime (future) |
| 1.3.2.1 | Habitat Loss/Degradation - Extraction - Fisheries - Subsistence (ongoing) |
| 1.3.6 | Habitat Loss/Degradation - Extraction - Groundwater extraction (future) |
| 1.4.1 | Habitat Loss/Degradation - Infrastructure development - Industry (present, future) |
| 1.4.2 | Habitat Loss/Degradation - Infrastructure development - Human settlement (ongoing) |
| 1.4.3 | Habitat Loss/Degradation - Infrastructure development - Tourism/recreation (ongoing) |
| 1.4.5 | Habitat Loss/Degradation - Infrastructure development - Transport (water) (present, future) |
| 1.4.6 | Habitat Loss/Degradation - Infrastructure development - Dams (future) |
| 1.8 | Habitat Loss/Degradation - Other causes (future) |
| 3.1.1 | Harvesting (hunting/gathering) - Food - Subsistence use/local trade (ongoing) |
| 3.1.2 | Harvesting (hunting/gathering) - Food - Sub-national/national trade (ongoing) |
| 3.2.1 | Harvesting (hunting/gathering) - Medicine - Subsistence use/local trade (past) |
| 3.4.1 | Harvesting (hunting/gathering) - Materials - Subsistence use/local trade (past) |
| 3.4.2 | Harvesting (hunting/gathering) - Materials - Sub-national/national trade (past) |
| 3.4.3 | Harvesting (hunting/gathering) - Materials - Regional/international trade (past) |
| 3.5.1 | Harvesting (hunting/gathering) - Cultural/scientific/leisure activities - Subsistence use/local trade (past) |
| 4.1.1.2 | Accidental mortality - Bycatch - Fisheries-related - Netting (ongoing) |
| 4.1.1.3 | Accidental mortality - Bycatch - Fisheries-related - Entanglement (ongoing) |
| 4.2.3 | Accidental mortality - Collision - Other (ongoing) |
| 6.3.1 | Pollution (affecting habitat and/or species) - Water pollution - Agriculture (ongoing) |
| 6.3.3 | Pollution (affecting habitat and/or species) - Water pollution - Commercial/Industrial (ongoing) |
| 6.3.10 | Pollution (affecting habitat and/or species) - Water pollution - Noise pollution (future) |
| 7.1 | Natural disasters - Drought (future) |
| 7.2 | Natural disasters - Storms/flooding (future) |
| 7.3 | Natural disasters - Temperature extremes (present, future) |
| 7.7 | Natural disasters - Other (present, future) |
| 8.5 | Changes in native species dynamics - Pathogens/parasites (future) |
| 9.2 | Intrinsic factors - Poor recruitment/reproduction/regeneration (ongoing) |
| 9.3 | Intrinsic factors - High juvenile mortality (ongoing) |
| 9.5 | Intrinsic factors - Low densities (ongoing) |
| 9.7 | Intrinsic factors - Slow growth rates (ongoing) |
| 9.9 | Intrinsic factors - Restricted range (ongoing) |
| 10.1 | Human disturbance - Recreation/tourism (present, future) |
| 10.4 | Human disturbance - Transport (present, future) |
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Conservation Actions
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Conservation Actions:
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Conservation of the Antillean manatee at the regional level has been driven by the SPAW Protocol to the Cartagena Convention (Freestone 1991), resulting in the Regional Management Plan for the West Indian Manatee, Trichechus manatus (UNEP 1995). In all countries with extant populations there is protective legislation with some effort towards conservation through governmental agencies and/or non-governmental organizations. In a few countries efforts have increased significantly over the past decade. Conservation measures include: (1) policy-based actions such as protective legislation, management plans, recovery plans, and community management; (2) educational outreach programs and awareness activities; (3) research actions such as site specific and country-wide surveys, behavioural studies both in captivity and in situ, remote sensing projects, health assessments, and genetic studies; (4) habitat and site-based actions such as protected areas and community-based initiatives; and (5) species-based actions such as re-introductions, stranding networks, and rehabilitation programs.
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List of Conservation Actions:
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| 1.1.1 | Policy-based actions - Management plans - Development (in place) |
| 1.1.2 | Policy-based actions - Management plans - Implementation (in place, needed) |
| 1.2.1.1 | Policy-based actions - Legislation - Development - International level (in place) |
| 1.2.1.2 | Policy-based actions - Legislation - Development - National level (in place) |
| 1.2.1.3 | Policy-based actions - Legislation - Development - Sub-national level (in place, needed) |
| 1.2.2.1 | Policy-based actions - Legislation - Implementation - International level (needed) |
| 1.2.2.2 | Policy-based actions - Legislation - Implementation - National level (in place, needed) |
| 1.2.2.3 | Policy-based actions - Legislation - Implementation - Sub-national level (in place, needed) |
| 1.3.1 | Policy-based actions - Community management - Governance (in place, needed) |
| 1.3.2 | Policy-based actions - Community management - Resource stewardship (in place, needed) |
| 1.3.3 | Policy-based actions - Community management - Livelihood alternatives (in place, needed) |
| 2.1 | Communication and Education - Formal education (needed) |
| 2.2 | Communication and Education - Awareness (in place, needed) |
| 2.3 | Communication and Education - Capacity-building/Training (needed) |
| 3.1 | Research actions - Taxonomy (in place, needed) |
| 3.2 | Research actions - Population numbers and range (in place, needed) |
| 3.3 | Research actions - Biology and Ecology (in place, needed) |
| 3.4 | Research actions - Habitat status (in place, needed) |
| 3.5 | Research actions - Threats (in place, needed) |
| 3.6 | Research actions - Uses and harvest levels (in place) |
| 3.7 | Research actions - Cultural relevance (in place) |
| 3.8 | Research actions - Conservation measures (in place, needed) |
| 3.9 | Research actions - Trends/Monitoring (in place, needed) |
| 4.1 | Habitat and site-based actions - Maintenance/Conservation (in place, needed) |
| 4.2 | Habitat and site-based actions - Restoration (in place, needed) |
| 4.3 | Habitat and site-based actions - Corridors (needed) |
| 4.4.1 | Habitat and site-based actions - Protected areas - Identification of new protected areas (needed) |
| 4.4.2 | Habitat and site-based actions - Protected areas - Establishment (in place, needed) |
| 4.4.3 | Habitat and site-based actions - Protected areas - Management (in place, needed) |
| 4.4.4 | Habitat and site-based actions - Protected areas - Expansion (in place, needed) |
| 4.5 | Habitat and site-based actions - Community-based initiatives (in place, needed) |
| 4.6 | Habitat and site-based actions - Other (needed) |
| 5.1 | Species-based actions - Re-introductions (in place, needed) |
| 5.4 | Species-based actions - Recovery management (in place, needed) |
| 5.5 | Species-based actions - Disease, pathogen, parasite management (needed) |
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Bibliography
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Bibliography:
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Baillie, J. and Groombridge, B. (compilers and editors) 1996. 1996 IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland. For the full list of references, see the species-level assessment (Trichechus manatus)
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