Dugong Habitat Research Articles

Spatial prioritization of dugong habitats in India can contribute towards achieving the 30 × 30 global biodiversity target

Indian coastal waters are critical for dugong populations in the western Indian Ocean. Systematic spatial planning of dugong habitats can help to achieve biodiversity conservation and area-based protection targets in the region. In this study, we employed environmental niche modelling to predict suitable dugong habitats and identify influencing factors along its entire distribution range in Indian waters. We examined data on fishing pressures collected through systematic interview surveys, citizen-science data, and field surveys to demarcate dugong habitats with varying risks. Seagrass presence was the primary factor in determining dugong habitat suitability across the study sites. Other variables such as depth, bathymetric slope, and Euclidean distance from the shore were significant factors, particularly in predicting seasonal suitability. Predicted suitable habitats showed a remarkable shift from pre-monsoon in Palk Bay to post-monsoon in the Gulf of Mannar, indicating the potential of seasonal dugong movement. The entire coastline along the Palk Bay-Gulf of Mannar region was observed to be at high to moderate risk, including the Gulf of Mannar Marine National Park, a high-risk area. The Andaman Islands exhibited high suitability during pre- and post-monsoon season, whereas the Nicobar Islands were highly suitable for monsoon season. Risk assessment of modelled suitable areas revealed that < 15% of high-risk areas across Andaman and Nicobar Islands and Palk Bay and Gulf of Mannar, Tamil Nadu, fall within the existing protected areas. A few offshore reef islands are identified under high-risk zones in the Gulf of Kutch, Gujarat. We highlight the utility of citizen science and secondary data in performing large-scale spatial ecological analysis. Overall, identifying synoptic scale ‘Critical Dugong Habitats’ has positive implications for the country's progress towards achieving the global 30 × 30 target through systematic conservation planning.

Seagrass, dugong, and people: Lessons learned from community-based conservation in Tolitoli Regency, Sulawesi Tengah, Indonesia

Dugong (Dugong dugon) is a protected mammal in Indonesia. Hunting for dugongs is still very high, so that the status of this animal is threatened, one of which is in Tolitoli Regency, Central Sulawesi. Hence, conservation efforts need to be carried out, both species and habitat area. Based on observation and interviews, dugong conservation in Tolitoli Regency was community-based habitat management. Kelompok Masyarakat Pengawas or Monitoring Community Group (Pokmaswas) was a form of community-based management in charge of maintaining, protecting, and preserving the existence of dugong and seagrass protection. From a community perspective, significant indicators in the management of dugong habitats were community awareness, seagrass percentage, and management quality. There was 11 kind of seagrass species have been identified in Tolitoli Regency. Seagrass conditions in all three villages were characterized by less than 60% of seagrass cover, especially seagrass that was close to the shoreline. The appearance of dugongs is based not only on good seagrass conditions but also on sea conditions and ship traffic.

Behavioral and Biophysical Studies of Dugong (Dugong dugon) Habitat in Waters Mali Beach, Kabola District, Indonesia.

Dugongs are generally shy animals, so observing their existence is very limited to hundreds of meters. In contrast to the behavior of Dugong who lives in the coastal waters of Mali, Kabola Regency, Indonesia. Its uniqueness can interact with humans at a very close distance and can even be on the back. It is, therefore, necessary to explore other behavioral patterns and habits and biophysical habitats of Dugongs as information to maintain their survival. This research aims to find out the behavior and biophysics of dugong habitat in the coastal waters of Mali, Kabola Subdistrict, Indonesia. The study uses direct observation methods in the form of observing the characteristics and biophysical conditions of dugong habitats including (1) determining dugong activity areas using GPS coordinates; (2) observe habitat characteristics and biophysical conditions by observing biotic and abiotic conditions, and (3) measuring physicochemical parameters, namely temperature, salinity, and pH. Next, to observe the daily behavior of dugongs when interacting with their habitat environment in the form of time: breathing, going around the boat, swimming at the bottom, swimming on the surface, swimming in the water column, resting at the bottom, eating and exposing the back. In the observations, dugongs swimming around the ship immediately responded and then approached and rubbed his body to the leg then through the pectoral fins that tried to hug to get a leg on the model being tested. Then turn under the boat and remove the penis. In general, the biophysical conditions of sandy and dense habitats are overgrown with seagrass.

Dugongs in Kenya – a survey on status and Trends

Purpose: The purpose of this study was to assess Dugongs' status distribution of dugongs (Dugong dugon) in Kenya. A dugong is a herbivorous marine mammal of the tropical and subtropical Indo-West Pacific and the Indian Ocean. Globally, IUCN classified the Dugong as rare; Kenya has done the same under the Wildlife Conservation and Management Act 2013, thus making Dugongs a conservation priority. The study's main objective was to assess dugongs' distribution and status for conservation in Kenya since the 1960s.&#x0D; Methodology: The study employed a concurrent triangulation design to corroborate findings from three methods. The study used a literature review, semi-structured questionnaires, guided interviews, and focus group discussions with respondents on obtaining socio-economic data. Data was collected in fishing villages with documented and or anecdotal records of the availability of dugongs. Experiences 378 fishers were reached for the study. The study aggregated the number of dugongs sited by decades from the six sampled study sites and presented the data on a line graph. Further, the study computed the rate of change in dugongs from one decade to the next.&#x0D; Findings: More than 100 dugongs occurred in the Kenyan waters in the 1960s; their population has declined considerably since then. The dugong habitat and feeding area have also shrunk over the same period, further aggravating the situation. There were more than thirty known dugong feeding areas in the study areas; only 10 of them are still known to host dugongs. An estimated 20 dugongs are known to be present in the Kenyan marine waters in the current times.&#x0D; Unique contribution to theory, practice and policy: This study confirmed the presence of dugongs in Kenya. Further, the dugong numbers are very small, thus showing an urgent need for their conservation. Dugongs are found in Kiunga and Kisite Marine Protected Areas (MPAs) and their immediate surroundings; this amplifies the conservation value of the MPAs.

Measuring the nonuse value of the dugong (Dugong dugon) in Thailand

The dugong is an herbivorous marine mammal species, being vulnerable to extinction throughout its range in the Indo-Pacific region. This article used the choice experiment method to elicit the nonuse value, or the nonusers’ willingness to pay for conserving the dugongs in Thailand. A face-to-face interview was used to obtain data from 300 residents in five selected districts of Bangkok. The results show that the average willingness to pay for the most preferred dugong conservation scheme (a marker buoy system, recreating habitats, and slowing down the population decline) was 4,382 Thai Baht (USD122) annually per household. Significantly, developing the marker buoy system to identify dugong habitats was the most valued by the general public. However, the respondents were not willing to pay for educating local fishers about the conservation of dugongs. Our results imply that a conservation policy should concentrate on the participation of key fishers in dugong protection projects using incentive measures. We also suggest the government to create protected areas as dugong sanctuaries that consistently support the remaining dugong population.

Evidence of behavioural thermoregulation by dugongs at the high latitude limit to their range in eastern Australia

Many species of marine mammals have evolved behavioural adaptations to minimize heat loss to the surrounding water. We tracked 21 dugongs (Dugong dugon Müller 1776) using acoustic and satellite/GPS transmitters in 2012, 2013 and 2014 in Moreton Bay, Queensland at the high latitude limit of the species' winter range in eastern Australia to examine if there was a relationship between movements and environmental temperature that might suggest behavioural thermoregulation. Oceanic waters immediately outside the bay where the dugong's seagrass food is unavailable exhibited temperatures from 5.5 °C warmer to 3 °C cooler than the Eastern Banks, the major dugong habitat in the bay. All tracked dugongs made at least one (and up to 66) return trip(s) from the Eastern Banks to the adjacent oceanic waters. The probability of making an outgoing trip was highest in 2014 and lowest in 2013 when the water temperature inside the bay was higher than the other two years. The odds of making an outgoing trip were lower when temperature differences (outside minus inside) were small or negative but increased by a factor of up to 2.12 for each 1 °C positive difference. Individual dugongs were most likely to travel out of the bay between midnight and noon on an outgoing tide or at slack high water and return to the bay on an incoming tide or slack low water between noon and midnight. The amount of time a dugong spent outside the bay on each trip was relatively short with an overall median of 5.9 h. The dugongs' individual activity spaces generally declined as winter progressed suggesting a change in the cost-effectiveness of moving outside the bay. Our analysis adds to the evidence that dugongs undertake behavioural thermoregulation at least at the high latitude limits of their range.

A low-cost solution for documenting distribution and abundance of endangered marine fauna and impacts from fisheries.

Fisheries bycatch is a widespread and serious issue that leads to declines of many important and threatened marine species. However, documenting the distribution, abundance, population trends and threats to sparse populations of marine species is often beyond the capacity of developing countries because such work is complex, time consuming and often extremely expensive. We have developed a flexible tool to document spatial distribution and population trends for dugongs and other marine species in the form of an interview questionnaire supported by a structured data upload sheet and a comprehensive project manual. Recognising the effort invested in getting interviewers to remote locations, the questionnaire is comprehensive, but low cost. The questionnaire has already been deployed in 18 countries across the Indo-Pacific region. Project teams spent an average of USD 5,000 per country and obtained large data sets on dugong distribution, trends, catch and bycatch, and threat overlaps. Findings indicated that >50% of respondents had never seen dugongs and that 20% had seen a single dugong in their lifetimes despite living and fishing in areas of known or suspected dugong habitat, suggesting that dugongs occurred in low numbers. Only 3% of respondents had seen mother and calf pairs, indicative of low reproductive output. Dugong hunting was still common in several countries. Gillnets and hook and line were the most common fishing gears, with the greatest mortality caused by gillnets. The questionnaire has also been used to study manatees in the Caribbean, coastal cetaceans along the eastern Gulf of Thailand and western Peninsular Malaysia, and river dolphins in Peru. This questionnaire is a powerful tool for studying distribution and relative abundance for marine species and fishery pressures, and determining potential conservation hotspot areas. We provide the questionnaire and supporting documents for open-access use by the scientific and conservation communities.

Differences in Vocalisation Patterns of Dugongs Between Fine-Scale Habitats Around Talibong Island, Thailand

Examining characteristics of a species’ fine-scale habitat use contributes to effective and practical spatially explicit conservation. Dugongs (Dugong dugon) are endangered herbivorous mammals that use vocalisation for communication. In a small, specific area of Thai waters, classified here as a “vocal hotspot,” vocalisation rates are elevated, implying that in this area acoustic communication plays an important role. We recorded dugong calls in the vocal hotspot and a nearby feeding area. We then compared temporal patterns of vocalisation between the two sites to investigate the degree of variability in vocalisation between fine-scale habitats, which is important for understanding dugong habitat use by passive acoustic monitoring. From the 489 total hours of recording, 6607 and 2032 calls were observed in the vocal hotspot and feeding area, with mean vocalisation rates (calls per hour) 13.5 and 4.2, respectively. Vocalisation rate had distinctive 24-h periodicity in only the vocal hotspot. Environmental factors that correlated with changes in detected vocalisation rate also differed between the two locations. Water level correlated with vocalisation rate in the feeding area; in contrast, current direction correlated with vocalisation rate in the vocal hotspot. In conclusion, the vocalisation pattern for dugongs differed between the two sites, and we suggest that their habitat use varies at fine spatial scales.

What the skull and scapular morphology of the dugong (Dugong dugon) can tell us: sex, habitat and body length?

The dugong (Dugong dugon, Müller) is an endangered marine mammal species. We examined the relationship between sex, habitat and body length based on the skull and scapular morphology and morphometrics of 81 dugong samples in Thailand. A total of 58 parameters from the skull and scapula (25 from the cranium, 23 from the mandible and 10 from the scapula) as well as tusks were used in this study. Data were analyzed by univariate analysis, followed by discriminant analysis and multivariate linear regression. Here we show, 100% and 98.5% accuracy rates for sexing using large tusks and the skull, respectively. Scapular morphology using the caudal border tubercle and coracoid process showed 91.30% and 96.15% accuracy rates for identifying males and females. Skull morphometrics could categorize dugong habitat, i.e. living in the Andaman Sea or Gulf of Thailand, with 100% accuracy. Moreover, our model could be used to estimate body length with coefficient of determination (R2) of 0.985. The results of our study showed that skull morphology and morphometric measurements could be used as a tool for sex identification, location identification and estimation of body length. But scapular morphology is the best tool for sex identification in dugongs.

Spatial mismatch between marine protected areas and dugongs in New Caledonia

Marine protected areas (MPAs) are a powerful tool for conserving marine biodiversity when designed using ecological information and conservation goals and targets. Dugongs (Dugong dugon) were not an explicit target in the design of the network of MPAs in New Caledonia, despite being one of the region’s World Heritage values. Our study retrospectively assessed the capacity of the New Caledonia MPA network to protect dugongs from anthropogenic threats. We developed a spatially explicit model of dugong distribution and relative density based on information collected from ∼10years of aerial surveys. We quantified the amount of overlap between areas supporting high densities of dugongs and MPAs. We found that most of the important dugong habitats of New Caledonia had a low coverage of MPAs that provide high levels of restriction on anthropogenic activities. We identified several important dugong habitats along the west and the north-east coast that were not covered by MPAs and should be a priority for future management. The spatial mismatch between MPAs and dugongs was likely caused by weaknesses in the planning process, including the: (1) lack of explicit conservation goals and targets; (2) omission of spatial information on species’ distribution; (3) mismatch of spatial scales; (4) cost considerations; and (5) incorrect application of the IUCN protected area categories. We provide guidance on how these shortcomings can be avoided for marine species of conservation concern in New Caledonia and other regions.

Is acoustic tracking appropriate for air-breathing marine animals? Dugongs as a case study

Marine animals face increased pressure through expanded shipping and recreational activities. Effective conservation and management of large species like marine mammals or sea turtles depend on knowledge of movement and habitat use. Previous studies have used data collected from either satellite or acoustic telemetry but rarely both. In this study, data from satellite and acoustic technologies were used to: determine the efficacy of satellite and acoustic telemetry to define dugong movement patterns; compare the benefits and limitations of each approach; examine the costs of each approach in relation to the amount and type of data provided; and relate telemetry data to the boundaries of a Go Slow area designed to protect dugongs and turtles from vessel strike within an urbanised coastal embayment (Moreton Bay, Queensland, Australia). Twenty-one dugongs were captured in seagrass habitats on the Eastern Banks of Moreton Bay in July–September 2012 and July 2013 and fitted with GPS and acoustic transmitters. Both satellite and acoustic telemetry produced reliable presence and movement data for individual dugongs. When the dugongs were within the range of the acoustic array, there was relatively good correspondence between the overall space use measures derived from GPS and acoustic transmitters, demonstrating that acoustic tracking is a potentially valuable and cost-effective tool for monitoring local dugong habitat use in environments equipped with acoustic receiver arrays. Acoustic technology may be particularly useful for species that establish home ranges with stable residency especially near large urban or port environs. However, the relative merits of the two technologies depend on the research question in the context of the species of interest, the location of the study and whether the study site has an established acoustic array.

Informing Species Conservation at Multiple Scales Using Data Collected for Marine Mammal Stock Assessments

BackgroundConservation planning and the design of marine protected areas (MPAs) requires spatially explicit information on the distribution of ecological features. Most species of marine mammals range over large areas and across multiple planning regions. The spatial distributions of marine mammals are difficult to predict using habitat modelling at ecological scales because of insufficient understanding of their habitat needs, however, relevant information may be available from surveys conducted to inform mandatory stock assessments.Methodology and ResultsWe use a 20-year time series of systematic aerial surveys of dugong (Dugong dugong) abundance to create spatially-explicit models of dugong distribution and relative density at the scale of the coastal waters of northeast Australia (∼136,000 km2). We interpolated the corrected data at the scale of 2 km * 2 km planning units using geostatistics. Planning units were classified as low, medium, high and very high dugong density on the basis of the relative density of dugongs estimated from the models and a frequency analysis. Torres Strait was identified as the most significant dugong habitat in northeast Australia and the most globally significant habitat known for any member of the Order Sirenia. The models are used by local, State and Federal agencies to inform management decisions related to the Indigenous harvest of dugongs, gill-net fisheries and Australia's National Representative System of Marine Protected Areas.Conclusion/SignificanceIn this paper we demonstrate that spatially-explicit population models add value to data collected for stock assessments, provide a robust alternative to predictive habitat distribution models, and inform species conservation at multiple scales.

Status of Dugong Dugong dugon and Australian Snubfin Dolphin Orcaella heinsohni, in the Solomon Islands

Dugong Dugong dugon are listed as Vulnerable on the IUCN Red List and are thought to be in global decline. The species has become extirpated from many areas in its range in the Indo-Pacific, and the largest remaining population is believed to occur in the coastal waters of northern Australia and Melanesia. This study is the first survey done to assess the current status of dugongs in the Solomon Islands, an archipelago potentially providing extensive dugong habitat within the many coastal lagoons and seagrass meadows. In a region where traditional hunting of dugong is carried out, in addition to the increasing threats to its coastal habitat, the survival of the dugong is uncertain. Interview surveys were conducted to assess abundance, distribution, level of traditional hunting and mortality, and community attitude towards conservation of the species. The surveys provide a provisional insight into the dugong population and mortality in the Solomon Islands. The surveys also obtained sighting data for the Australian Snubfin Dolphin Orcaella heinsohni, a species endemic to Australia and Melanesia, but for which little occurrence information is available. The results indicate that dugong occur throughout the Solomon Islands, but rates of anthropogenic mortality are of concern, emphasising the potential value of protected areas and community engagement projects for the conservation of dugongs in this region.

Community interviews on the status of the dugong (Dugong dugon) in the Gulf of Mannar (India and Sri Lanka)

The World Conservation Union (IUCN) Red List of Threatened Species lists the dugong (Dugong dugon) as vulnerable throughout its range (IUCN 2006). The Gulf of Mannar and Palk Strait, located between northwest Sri Lanka and southeast India (Fig. 1) in the northern Indian Ocean, is known to be an area where dugongs were abundant historically (Haley 1883, Phillips 1927). Dugongs are presently considered endangered in both countries and are legally protected under the Fauna and Flora Protection Ordinance of Sri Lanka (1970) and theWildlife Protection Act of India (1972). Marine protected areas (MPAs) in both countries cover small parts of the known dugong habitat in the Gulf of Mannar, the Bar Reef Marine Sanctuary (306.7 km2 in extent) in Sri Lanka, and the Gulf of Mannar Marine Biosphere Reserve (21 islands on the Indian side of the Gulf of Mannar) in India.

A spatial assessment of the risk to a mobile marine mammal from bycatch

Abstract Several species of marine mammals are at risk of extinction from being captured as bycatch in commercial fisheries. Various approaches have been developed and implemented to address this bycatch problem, including devices and gear changes, time and area closures and fisheries moratoria. Most of these solutions are difficult to implement effectively, especially for artisanal fisheries in developing countries and remote regions. Re‐zoning of the Great Barrier Reef World Heritage Area (GBRWHA) in 2004 closed 33% of the region to extractive activities, including commercial fishing. However, the impact of re‐zoning and the associated industry restructuring on a threatened marine mammal, the dugong (Dugong dugon), is difficult to quantify. Accurate information on dugong bycatch in commercial nets is unavailable because of the large geographic extent of the GBRWHA, the remoteness of the region adjacent to the Cape York Peninsula where most dugongs occur and the artisanal nature of the fishery. In the face of this uncertainty, a spatial risk‐assessment approach was used to evaluate the re‐zoning and associated industry restructuring for their ability to reduce the risk of dugong bycatch from commercial fisheries netting. The new zoning arrangements appreciably reduced the risk of dugong bycatch by reducing the total area where commercial netting is permitted. Netting is currently not permitted in 67% of dugong habitats of high conservation value, a 56% improvement over the former arrangements. Re‐zoning and industry restructuring also contributed to a 22% decline in the spatial extent of conducted netting. Spatial risk assessment approaches that evaluate the risk of mobile marine mammals from bycatch are applicable to other situations where there is limited information on the location and intensity of bycatch, including remote regions and developing countries where resources are limited. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Incorporating dugong habitats into the marine protected area design for the Great Barrier Reef Marine Park, Queensland, Australia

Dugong habitats were considered in the design for the new zoning network for the Great Barrier Reef Marine Park as part of the Representative Areas Program. One of the specific design guidelines developed as part of the biophysical operational principles recommended that 50% of all high priority dugong habitats should be incorporated in the network of no-take areas. The high priority dugong habitat incorporated in no-take protection increased from 1396 to 3476 km 2 (or 16.9–42.0% of all identified sites). Although this increase in protection fell short of the recommended 50%, overall the level of protection afforded by the Great Barrier Reef Marine Park Zoning Plan 2003 increased for all the locations identified.

Atypical associations between dugongs (Dugong dugon) and dolphins in a tropical lagoon

Several types of relationships link organisms to each other, including competition, predation and various types of associations. This paper presents the first case of association/interaction between dugongs, Dugong dugon, the only strictly marine herbivorous mammal, and three species of tropical dolphins in and around the lagoon of Mayotte (45°10'E 12°50'S), in the western tropical Indian ocean. Data were collected opportunistically from 1999 to 2005 in the surrounding waters of Mayotte from boat (N=2 observations) and ULM (ultra-light motorized vessel, N=2). The dolphin species involved in associations with dugongs were Indo-Pacific bottlenose dolphin, Tursips aduncus, Indo-Pacific humpback dolphin, Sousa chinensis, and spinner dolphin, Stenella longirostris. In one case, dugongs were associated with both bottlenose and humpback dolphins. Associations were observed in the protected waters of the lagoon and outside, along the external slope of the barrier reef. Group size, activity and group structure of each species were recorded. Behavioural observations suggest that dugongs and dolphins were engaged in similar activities, such as travelling, on several occasions and were clearly associated when group formation was tight. If dolphins and dugongs may not associate for feeding purposes, then these interactions may occur: (1) for predation avoidance toward sharks; or (2) without any ecological reasons due to dolphin and dugong habitat overlap around the island.

Seagrass as pasture for seacows: Landscape-level dugong habitat evaluation

A 24 km 2 seagrass meadow in Hervey Bay, Queensland, Australia, was confirmed as important dugong habitat by a satellite tracking study. Marine videography, near-infrared spectroscopy (NIRS) and geographic information systems (GIS) were used to survey, analyse and map seagrass species composition, nutrient profile and patch structure at high resolution (200 m). Five species of seagrass covered 91% of the total habitat area. The total above and below-ground seagrass biomass was estimated to be 222.7 ± 19.6 t dry-weight. Halodule uninervis dominated the pasture (81.8%, 162.2 t), followed by Halophila ovalis (35.3%, 16.5 t), Zostera capricorni (15.9%, 22.2 t), Halophila spinulosa (14.5%, 21.9 t), and traces of Halodule pinifolia. Because seagrass distributions overlapped, their combined percentage totalled >100% of the survey area. The seagrass formed a continuous meadow of varying density. Abiotic variables explained relatively little of the spatial patterns in the seagrass. For all seagrass species, the above-ground component (shoots and leaves) possessed greater total nitrogen than the below-ground component (roots and rhizomes), which possessed greater total starch. Because of the relatively low intraspecific variation in nutrient composition, nutrients were concentrated according to seagrass biomass density. Halodule uninervis was the most nutritious seagrass species because of its superior whole-plant nitrogen (1.28 ± 0.05% DW) and starch (6.42 ± 0.50 DW %) content. Halodule uninervis formed large, clustered patches of dense biomass across the pasture and thus nitrogen and starch were concentrated where H. uninervis was prevalent. This seagrass meadow appears to be utilised well below its potential dugong carrying capacity. The survey and analytical techniques used enabled rapid, economical and accurate quantification and characterisation of seagrass habitat at scales relevant to a large forager.

Investigation of the northern limit of dugong habitat in the Tokara Islands and Amami-Oshima in the Ryukyu archipelago, Japan

Investigation of the northern limit of dugong habitat in the Tokara Islands and Amami-Oshima in the Ryukyu archipelago, Japan

Observations on dugongs at Calauit Island, Busuanga, Palawan, Phillipines

A simultaneous monitoring system that used a team of local observers to count dugongs around Calauit Island, Busuanga, Palawan, Philippines, from eight vantage points was employed from March 1989 to May 1990 to identify important dugong habitats around the island. On average, five dugongs were seen per survey day. More dugongs were observed during March and July 1989 than in other months. These periods coincided with the bimodal peaking of seagrass biomass in the region and the lull between monsoons for that year. The site where dugongs were most often sighted was about 1.5 m deep, had the largest area of seagrass on the island (approximately 50 ha) and supported a seagrass (above-ground) biomass averaging 1060 g m-2 (wet weight). The dugongs were shy, making observations difficult. They were observed to graze at the study sites once per day, usually starting in the late afternoon or at night. Animals usually stayed on the seaward side of the spur-and-groove sections of the reefs. Short seagrasses such as Halophila ovalis, Halodule uninervis, Cymodocea rotundata, C. serrulata, Syringodium isoetifolium and Thalassia hemprichii showed more evidence of being grazed than the taller Enhalus acoroides. By direct observations of the area grazed by a single dugong, an average consumption rate of 30.5 kg (wet weight) of seagrass (above ground only) per day was estimated. The methodology developed in this study may be used to identify reserve areas for the protection of dugong habitats in the Philippines. The dugong populations of Palawan require further attention and implementation of conservation measures.