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We report the occurrence of the reef manta ray Manta alfredi Krefft 1868 in the Bohol Sea, Philippines, based on photographic evidence from boat-based surveys and a fishery specimen. Despite previous anecdotal reports from the diving industry and over a century of extensive targeted fisheries for mobulid rays in the Philippines, it was not until recently that the species was first confirmed in the country at the Tubbataha Reefs Natural Park, Palawan. Our results confirm the presence of M. alfredi in the Visayas region of the Philippines, extending the current range for the species from the Sulu Sea over 600 km eastwards. Its presence in a region with an active mobulid fishery has important implications for the conservation and management of M. alfredi in the country. We highlight the need to understand the distribution of M. alfredi in the region and make management recommendations based on the present study.

Seven species of mobulid rays occur in the Philippines, six of which, including the Giant Manta Ray (Manta birostris) are caught directly or indirectly. In the Bohol Sea, mobulids have been fished since at least the nineteenth century yet the extent is not well-understood. A second species of manta, Manta alfredi was taxonomically resurrected in 2009 and also only recently been confirmed to occur in the Philippines. This study aimed to identify and describe the presence of and fishery for M. alfredi in a previously unknown area of occurrence in the Philippines. Key informant interviews, observation of catch landings, and tissue sample collection were conducted in a fishing village off Dinagat Island. Based on morphological examination and through DNA barcoding using the mitochondrial DNA CO1 gene of tissue samples it was verified that the species targeted in this area is the reef manta ray, Manta alfredi. Local ecological knowledge of the fishers provided important information on the extent and characteristics of the fishery. This relatively recent ray fishery in the Surigao Strait is the source of mobulids during the off-fishing season in Bohol with fishers from this area transporting and selling their processed catches to Bohol. The description of this fishery and habitat for the reef manta ray in the Surigao Strait is important in the understanding of the status of the species in the Philippines and in designing a management framework.

Temporal variation in demographic processes can greatly impact population dynamics. Perturbations of statistical coefficients that describe demographic rates within matrix models have, for example, revealed that stochastic population growth rates (log(λs)) of fast life histories are more sensitive to temporal autocorrelation of environmental conditions than those of slow life histories. Yet, we know little about the mechanisms that drive such patterns. Here, we used a mechanistic, functional trait approach to examine the functional pathways by which a typical fast life history species, the macrodetrivore Orchestia gammarellus, and a typical slow life history species, the reef manta ray Manta alfredi, differ in their sensitivity to environmental autocorrelation if (a) growth and reproduction are described mechanistically by functional traits that adhere to the principle of energy conservation, and if (b) demographic variation is determined by temporal autocorrelation in food conditions. Opposite to previous findings, we found that O. gammarellus log(λs) was most sensitive to the frequency of good food conditions, likely because reproduction traits, which directly impact population growth, were most influential to log(λs). Manta alfredi log(λs) was instead most sensitive to temporal autocorrelation, likely because growth parameters, which impact population growth indirectly, were most influential to log(λs). This differential sensitivity to functional traits likely also explains why we found that O. gammarellus mean body size decreased (due to increased reproduction) but M. alfredi mean body size increased (due to increased individual growth) as food conditions became more favorable. Increasing demographic stochasticity under constant food conditions decreased O. gammarellus mean body size and increased log(λs) due to increased reproduction, whereas M. alfredi mean body and log(λs) decreased, likely due to decreased individual growth. Our findings signify the importance of integrating functional traits into demographic models as this provides mechanistic understanding of how environmental and demographic stochasticity affects population dynamics in stochastic environments.

This paper presents an end-to-end deep learning approach for the fine-grained identification of individual manta rays (Manta alfredi) based on characteristic ventral coat patterns where training is restricted to sparse photographic sets of

Manta rays (Manta spp.) are among the largest elasmobranch fishes and currently comprise two recognised species, the reef manta ray Manta alfredi and the giant manta ray Manta birostris. Both Manta spp. have circumglobal distributions in tropical and temperate oceans, however, M. alfredi is more commonly encountered in coastal environments, whereas M. birostris is generally more elusive and typically sighted offshore. As such, collection of information on the feeding ecology, and the identification of drivers of habitat use for M. birostris has been difficult, particularly given the paucity of accessible and predictable locations where this species occurs.A newly discovered aggregation site at Isla de la Plata, off mainland Ecuador, hosts the largest known population of M. birostris from June to October each year, with over 2400 individuals recorded since 2009. However, the drivers for this seasonal aggregation within the Humboldt upwelling system are unknown. As aggregative behaviour of planktivorous elasmobranchs is often attributed to food availability, the aim of this study was to examine whether feeding opportunities constitute the primary driver of this sizeable aggregation of M. birostris at Isla de la Plata.We first define the inter-annual and seasonal variation in recorded numbers of M. birostris and investigate the relationship between M. birostris sightings and environmental variables at Isla de la Plata. The primary source of variability in physical processes and biological production in the Humboldt Current upwelling system is the El Nino-Southern Oscillation (ENSO), where primary production declines during the negative El Nino phase, and increases during the positive La Nina phase. Data comprising the daily sightings of M. birostris were collected over a five-year period (2011 – 2015), and a generalised linear model was used to identify the effect of El Nino on the presence of individual M. birostris. Overall, month and ENSO activity explained 27.7 % of the variability in M. birostris sightings between years. The number of individual M. birostris sighted off mainland Ecuador was significantly higher during years with La Nina and neutral ENSO conditions in comparison to El Nino conditions, suggesting that overall food availability in this region is likely to be important for this species.To investigate the importance of local food availability and occurrence of M. birostris at Isla de la Plata, we determined near-surface zooplankton biomass, size structure and community composition in relation to M. birostris daytime foraging activity. When M. birostris was feeding there was higher zooplankton biomass in comparison to background non- feeding events. However, foraging activity was rarely observed at this aggregation site (6 % of all observations), which suggests that local food availability at Isla de la Plata during the day is not a major driver of M. birostris aggregative behaviour. In comparison, cleaning was the most common behaviour recorded during daytime hours (54 % of all observations), with significant predictors conducive to efficient cleaning interactions such as, weak currents and good water clarity, explaining 44.8 % of the total variance in M. birostris sightings at Isla de la Plata. As boat-based plankton sampling and observations of M. birostris were only possible around Isla de la Plata during the daytime, M. birostris activity and location during night time hours were not able to be determined.Non-lethal and minimally-invasive molecular methods were used to indirectly examine the feeding ecology and habitat use of M. birostris. To investigate the contribution of near-surface zooplankton to the long-term diet of M. birostris, we conducted bulk stable isotope (SIA) and fatty acid (FA) analyses on M. birostris muscle biopsies, as these provide an integrated (‘time-averaged’) signal of overall dietary intake. In addition, we conducted SIA on epidermal mucus, a rapid-to-medium turnover rate ‘tissue’, collected from M. birostris to assess the importance of near-surface zooplankton to the recent diet of this species. There was large variation in M. birostris mucus and muscle δ15N and δ13C values among individuals, indicating either a generalist feeding strategy or a population made up of individual specialists. Trophic position (TP) estimates from M. birostris muscle δ15N placed this species at a secondary consumer level, however, the broad range of δ15N values and subsequent calculated TPs are likely indicative of the targeting of higher level trophicprey, as well as primary producer baseline shifts. There was a broader range in mucus δ13C values in comparison to muscle, suggesting that resource use during aggregative behaviour off Ecuador is broader, but with no obvious resource switching. Manta birostris muscle tissue δ13C values were not consistent with this species feeding predominantly on surface zooplankton. Further, the FA profiles between M. birostris muscle and surface zooplankton were markedly different, with the FA profile of M. birostris muscle depleted in polyunsaturated fatty acids, which were the dominant constituent of surface zooplankton FA profiles. Instead, the FA profile of M. birostris was dominated by 18:1w9 isomers, which are commonly found in high proportions in deep-sea organisms. Taken together, findings from SIA and FA challenge the traditionally held view that surface zooplankton is the dominant component of M. birostris diet, and instead, suggest that the majority of dietary intake for M. birostris is mesopelagic in origin.The rarity of observed M. birostris feeding activity at the Isla de la Plata does not provide support for aggregative behaviour of this species being driven by daytime feeding opportunities. Alternatively, it is possible that this daytime aggregation of M. birostris is related to the presence of cleaning stations at Isla de la Plata, and that the island is an important cleaning site given the prevalence of cleaning behaviour. However, as sightings of M. birostris increased during La Nina conditions, when increased upwelling creates a more favourable food environment in the eastern Pacific, the broader, regional availability of food may ultimately drive M. birostris to aggregate at this site. The diet of M. birostris was dominated by mesopelagic prey sources, which may be targeted by M. birostris in offshore, possibly shelf-edge habitats, where they could feed on vertically migrating prey assemblages, such as euphausiids during night time hours. This possibility is consistent with the fact that Isla de la Plata is situated

Populations of mobulid rays are declining globally through a combination of directed fisheries and indirect anthropogenic threats. Understanding the movement ecology of these rays remains an important priority for devising appropriate conservation measures throughout the world’s oceans. We sought to determine manta movements across several temporal and spatial scales with a focus on quantifying site fidelity and seasonality in the northern Farasan Banks, Red Sea. We fitted manta rays with acoustic transmitters (n = 9) and pop-up satellite archival transmitting (PSAT) tags (n = 9), including four with GPS capability (Fastloc), during spring 2011 and 2012. We deployed an extensive array of acoustic receivers (n = 67) to record movements of tagged mantas in the study area. All acoustically tagged individuals traveled frequently among high-use receiver locations and reefs and demonstrated fidelity to specific sites within the array. Estimated and realized satellite tag data indicated regional movements

Manta rays (Manta spp.) are plankton-feeding elasmobranchs classified as vulnerable to extinction on the IUCN Red List for Threatened Species. Despite increasing public and scientific interest in manta rays, major knowledge gaps concerning their movement ecology and dispersal capabilities remain. Here, we used pop-off satellite-linked archival transmitting tags to examine the horizontal movements and habitat use patterns of reef manta rays (M. alfredi) departing Lady Elliot Island in the southern Great Barrier Reef, Australia. Tagged individuals moved across a latitudinal range of 1035 km, travelling up to 2441 km in 118 d, diving down to 294.5 m and venturing up to 155 km off the continental shelf. Using random walk simulations, we showed that manta rays spent significantly more time in an offshore region characterised by the mesoscale cyclonic Capricorn Eddy than would be expected by chance. A behaviour-switching state-space model suggested this area to be an important foraging ground for M. alfredi off eastern Australia. We document the movements of 1 individual using offshore waters between 2 known aggregation regions off eastern Australia. Reef manta rays thus not only occupy inshore continental shelf and shelf-edge waters but also use offshore environments to exploit productive hotspots and travel long distances. Our findings highlight the need to better understand their movement ecology for effective management.

Quantifying the ecological importance of individual habitats to highly mobile animals is challenging because patterns of habitat reliance for these taxa are complex and difficult to observe. We investigated the importance of lagoons to the manta ray, Manta alfredi, a wide-ranging and vulnerable species in a less-disturbed atoll ecosystem. Lagoons are highly sensitive to anthropogenic disturbance and are known to be ecologically important to a wide variety of mobile species. We used a novel combination of research tools to examine the reliance of M. alfredi on lagoon habitats. Stable isotope analysis was used to assay the recent energetic importance of lagoons to M. alfredi; high-resolution tracking data provided information about how M. alfredi utilised lagoonal habitats over long and short time periods; acoustic cameras logged patterns of animal entrances and departures from lagoons; and photo identification/laser photogrammetry provided some insight into why they may be using this habitat. M. alfredi showed strong evidence of energetic dependence on lagoon resources during the course of the study and spent long periods of residence within lagoons or frequently transited into them from elsewhere. While within lagoons, they demonstrated affinities for particular structural features within this habitat and showed evidence of temporal patterning in habitat utilization. This work sheds light on how and why M. alfredi uses lagoons and raises questions about how this use may be altered in disturbed settings. More generally, these observations contribute to our knowledge of how to assess the ecological importance of particular habitats situated within the broader home range of mobile consumers. © 2014 Springer-Verlag Berlin Heidelberg.

The reef manta ray Manta alfredi aggregates at several sites along the east coast of Australia. Photographic identification and mark–recapture methods were used to report on the site affinity, size and structure of this population of M. alfredi. A total of 716 individuals were identified in 1982–2012, including 636 at Lady Elliot Island (LEI), southern Great Barrier Reef. Over 60 % of individuals identified were resighted at least once during the study period. Multiple resightings within and among years imply a high degree of site affinity by individuals to aggregation sites. One individual was sighted 11 times at LEI over a 30-yr period. The sex ratio of this population was significantly biased towards females (1.2:1 female-to-male ratio), and females were more commonly resighted than males. Robust design population models were used to estimate the population size of the winter aggregation at LEI over a 4-yr period. The models estimated up to 456 (95 % CI 399–535) M. alfredi individuals in the population within one winter season and a high annual apparent survival. This study demonstrated that waters around LEI form a key aggregation site for a large portion of the M. alfredi population in east Australian waters.

Fatty acid (FA) signature analysis has been increasingly used to assess dietary preferences and trophodynamics in marine animals. We investigated FA signatures of connective tissue of the whale shark Rhincodon typus and muscle tissue of the reef manta ray Manta alfredi. We found high levels of n-6 polyunsaturated fatty acids (PUFA), dominated by arachidonic acid (20:4n-6; 12–17 % of total FA), and comparatively lower levels of the essential n-3 PUFA—eicosapentaenoic acid (20:5n-3; ~1 %) and docosahexaenoic acid (22:6n-3; 3–10 %). Whale sharks and reef manta rays are regularly observed feeding on surface aggregations of coastal crustacean zooplankton during the day, which generally have FA profiles dominated by n-3 PUFA. The high levels of n-6 PUFA in both giant elasmobranchs raise new questions about the origin of their main food source.

Sightings of planktivorous elasmobranchs at their coastal aggregation sites are often linked to biological, environmental and temporal variables. Many large planktivorous elasmobranchs are also globally threatened species, so it is necessary to try and separate population trends from environmentally driven, short-term fluctuations. We investigated the influence of environmental variables on sightings of 3 species of planktivorous elasmobranchs off Praia do Tofo, Mozambique: the reef manta ray Manta alfredi, giant manta ray M. birostris and whale shark Rhincodon typus. We used 8- (2003 to 2011) and 6-yr (2005 to 2011) logbook data for manta rays and whale sharks, respectively, and constructed a generalised linear model with animal sightings as the response. Predictors included temporal (year, month, time of day), biological (plankton categories), oceanographic (water temperature, time from high tide, current direction and strength and wave height) and celestial (moon illumination) indices. These predictors best fitted reef manta ray sightings, a coastal species with high residency, but less so for the wider-ranging giant manta rays and whale sharks. We found a significant decline in the standardised sightings time series for the reef manta ray (88%) and whale shark (79%), but not for the giant manta ray.

An adult, female, reef manta ray (Manta alfredi) was evaluated for abnormal swimming and coelomic distention after colliding with a floating dock in an exhibit. Initial clinical signs included abnormal posture and swimming. Clinical signs progressed to include muscle wasting, poor body condition, and coelomic distention. Further diagnostics revealed excessive exhibit substrate within the gastrointestinal tract, gastric ulcers, free coelomic fluid, possible spinal lesion, possible uterine abnormality, and hematologic changes. The ray was treated with repeated gastroscopic examinations to remove substrate from the stomach. Psyllium and mineral oil were administered in gel food to assist with passage of substrate through the gastrointestinal tract. Gastric ulcers were treated with sucralfate. Vitamin B complex, iron dextran, and Yunnan Paiyao were used to treat the anemia. Amikacin and sulfadimethoxine-ormetoprim were administered for suspected bacterial and coccidial infections, respectively. Over the course of 11 mo the ray returned to normal health.

BackgroundThe trade in manta ray gill plates has considerably increased over the last two decades. The resulting increases in ray mortality, in addition to mortality caused by by-catch, has caused many ray populations to decrease in size. The aim of this study was to ascertain how yearling and juvenile growth and survival, and adult survival and reproduction affect reef manta ray (Manta alfredi) population change, to increase our understanding of manta ray demography and thereby improve conservation research and measures for these fish.MethodsWe developed a population projection model for reef manta rays, and used published life history data on yearling and juvenile growth and adult reproduction to parameterise the model. Because little is known about reef manta ray yearling and juvenile survival, we conducted our analyses using a range of plausible survival rate values for yearlings, juveniles and adults.ResultsThe model accurately captured observed variation in population growth rate, lifetime reproductive success and cohort generation time in different reef manta ray populations. Our demographic analyses revealed a range of population consequences in response to variation in demographic rates. For example, an increase in yearling or adult survival rates always elicited greater responses in population growth rate, lifetime reproductive success and cohort generation time than the same increase in juvenile survival rate. The population growth rate increased linearly, but lifetime reproductive success and cohort generation time increased at an accelerating rate with increasing yearling or adult survival rates. Hence, even a small increase in survival rate could increase lifetime reproductive success by one pup, and cohort generation time by several years. Elasticity analyses revealed that, depending on survival rate values of all life stages, the population growth rate is either most sensitive to changes in the rate with which juveniles survive but stay juveniles (i.e., do not mature into adults) or to changes in adult survival rate. However, when assessing these results against estimates on population growth and adult survival rates for populations off the coasts of Mozambique and Japan, we found that the population growth rate is predicted to be always most sensitive to changes in the adult survival rate.DiscussionIt is important to gain an in-depth understanding of reef manta ray life histories, particularly of yearling and adult survival rates, as these can influence reef manta ray population dynamics in a variety of ways. For declining populations in particular, it is crucial to know which life stage should be targeted for their conservation. For one such declining population off the coast of Mozambique, adult annual survival rate has the greatest effect on population growth, and by increasing adult survival by protecting adult aggregation sites, this population’s decline could be halted or even reversed.

International audience; Large tropical and sub-tropical marine animals must meet their energetic requirements in a largely oligotrophic environment. Many planktivorous elasmobranchs, whose thermal ecologies prevent foraging in nutrient-rich polar waters, aggregate seasonally at predictable locations throughout tropical oceans where they are observed feeding. Here we investigate the foraging and oceanographic environment around Lady Elliot Island, a known aggregation site for reef manta rays Manta alfredi in the southern Great Barrier Reef. The foraging behaviour of reef manta rays was analysed in relation to zooplankton populations and local oceanography, and compared to long-term sighting records of reef manta rays from the dive operator on the island. Reef manta rays fed at Lady Elliot Island when zooplankton biomass and abundance were significantly higher than other times. The critical prey density threshold that triggered feeding was 11.2 mg m(-3) while zooplankton size had no significant effect on feeding. The community composition and size structure of the zooplankton was similar when reef manta rays were feeding or not, with only the density of zooplankton changing. Higher zooplankton biomass was observed prior to low tide, and long-term (similar to 5 years) sighting data confirmed that more reef manta rays are also observed feeding during this tidal phase than other times. This is the first study to examine prey availability at an aggregation site for reef manta rays and it indicates that they feed in locations and at times of higher zooplankton biomass.

Background. The trade in gill plates of devil and manta rays has increased greatly over the last two decades. The resulting increased mortality, in addition to mortality caused by by-catch, means that many ray populations are declining in size. The aim of this study was to ascertain the main demographic drivers of population change in reef manta rays (Manta alfredi) to increase our understanding of their demography and hence provide insight into potential conservation measures. Methods. We developed a population projection model for reef manta rays and used published life history data to parameterise the model and also used these data as points of reference to compare our model output to. Because little is known about yearling and juvenile survival of reef manta rays, we conducted our analyses across a range of plausible survival rate values of yearlings, juveniles, and also adults. Results. The model accurately captured observed patterns of variation in population growth rate, lifetime reproductive success and cohort generation time for different reef manta ray populations around the world. Varying the survival rates of the different life stages revealed that increasing adult annual survival rate always positively and additively affected population growth rate, lifetime reproductive success and cohort generation time. Variation in yearling and juvenile annual survival rate, however, had different and varying effects on the latter three population descriptors, highlighting the importance of obtaining accurate estimates of these survival rates from natural populations. Our elasticity analysis revealed that for both declining and stable populations, the population growth rate is most sensitive to changes in either juvenile or adult survival rate, depending on yearling and adult annual survival rate values. Discussion. Many reef manta ray populations are declining, resulting in local extinction unless effective conservation measures are taken. Based on our detailed demographic analysis, we suggest that reef manta ray conservation would particularly benefit from focusing on increasing juvenile and adult survival.

We isolated and characterised ten microsatellite loci from the reef manta ray, Manta alfredi. Loci were screened for 60 individuals from Japan. The number of alleles per locus ranged from 2 to 10 and observed heterozygosity ranged from 0.033 to 0.867. Cross-species amplification was successful in the sister species M. birostris (9/10 loci) and other mobulids, Mobula japanica (7/10), M. thurstoni (8/10) and M. tarapacana (5/10). These loci provide new tools for assessing population genetic structuring and genetic monitoring.

The Mobulidae are zooplanktivorous elasmobranchs comprising two recognized species of manta rays (Manta spp.) and nine recognized species of devil rays (Mobula spp.). They are found circumglobally in tropical, subtropical and temperate coastal waters. Although mobulids have been recorded for over 400 years, critical knowledge gaps still compromise the ability to assess the status of these species. On the basis of a review of 263 publications, a comparative synthesis of the biology and ecology of mobulids was conducted to examine their evolution, taxonomy, distribution, population trends, movements and aggregation, reproduction, growth and longevity, feeding, natural mortality and direct and indirect anthropogenic threats. There has been a marked increase in the number of published studies on mobulids since c. 1990, particularly for the genus Manta, although the genus Mobula remains poorly understood. Mobulid species have many common biological characteristics although their ecologies appear to be species-specific, and sometimes region-specific. Movement studies suggest that mobulids are highly mobile and have the potential to rapidly travel large distances. Fishing pressure is the major threat to many mobulid populations, with current levels of exploitation in target fisheries unlikely to be sustainable. Advances in the fields of population genetics, acoustic and satellite tracking, and stable-isotope and fatty-acid analyses will provide new insights into the biology and ecology of these species. Future research should focus on the uncertain taxonomy of mobulid species, the degree of overlap between their large-scale movement and human activities such as fisheries and pollution, and the need for management of inter-jurisdictional fisheries in developing nations to ensure their long-term sustainability. Closer collaboration among researchers worldwide is necessary to ensure standardized sampling and modelling methodologies to underpin global population estimates and status.

The Alfred manta, Manta alfredi, is economically important in the Maldives due to the large number of tourists attracted to SCUBA dive and snorkel with them. It is important to understand the size of populations around main diving points and throughout the Maldives so that manta based tourism activities can be developed more successfully and the impact of tourism can be monitored. Using natural markings to identify individual manta rays, Petersen and Jolly-Seber probabilistic estimators were used to assess population size for main dive sites and the central atolls of North Male, Ari and Baa. Between 2000 and 2009, 1835 individual mantas were identified from 3373 sightings. There was a significant gender bias with a male: female ratio of 1:1.8. Only 24.7% of manta rays were re-sighted between 1 and 34 times with a maximum gap of 7 years and 11 months between sightings. Estimates for populations around main dive sites were 181–562. The estimated population of M. alfredi for North Male atoll is 537 (SE ± 53.2). Estimated atoll populations were extrapolated to obtain an estimate of Manta alfredi population for the entire Maldives of 9,677 individuals.

In resident manta rays (Manta alfredi) off Maui, sexual maturity appears delayed until growth exceeds 90% of maximum size, an indicator that large body size provides a reproductive advantage at the expense of a shorter reproductive time period. In this study, 286 surveys were conducted between 2005 and 2010 using photo-identification and photogrammetry to study the reproductive ecology of a resident population of manta rays off Maui, Hawaii, and investigate the reproductive benefits of large body size in each sex. Although reproductive activities occurred year-round, mating trains and late-term pregnant females were significantly more likely to be observed during the winter months. Some females were pursued by males during both winter and summer of the same year, suggesting multiple ovulations may be possible in a single year. Males likely detect a female’s reproductive state by positioning directly behind her, or passing through her bodily excretions. The mean pregnancy rate was estimated at 0.56 pregnancies/adult female/year with larger females pregnant more often, and more likely in consecutive years. The operational sex ratio was heavily skewed with 2.68 adult males per reproductively available female. Although males appear to compete with one another for females within a mating train, no direct physical competition was ever observed between males. Evidence of highly dynamic mating trains lasting more than one day suggests endurance rivalry may be the primary mating strategy among males, during which larger males may benefit from greater energy reserves. The study area appears to be an important staging area for mating individuals in this population.

Late maturity, few offspring and a residential nature are typical characteristics of Manta alfredi that make this species vulnerable to localized anthropogenic threats. Improving its life history information is crucial for successful management. A total of 229 surveys was conducted from 2005 to 2009 at a manta ray aggregation site off Maui, Hawaii, to qualitatively and quantitatively describe the abundance, movements and temporal habits of this population. Photo-identifications revealed 290 unique individuals, but a discovery curve showed no asymptotic trend, indicating that the number of individuals using the area was much larger. Resightings and manta ray follows revealed that this pop- ulation and a population off the Big Island may be independent, island-associated stocks. High resighting rates within and across years provided strong evidence of site fidelity. Findings were con- sistent with a population of manta rays moving into and out of the Maui aggregation area, with a varying portion of the total population temporarily resident at any given time. Males, accounting for 53% of all individuals, resided for shorter periods than females around the study area. Manta rays were usually absent at first light with numbers increasing throughout the day. More frequent mating trains were observed during the winter months. Shark predation was evident in 33% of individuals, and 10% had an amputated or non-functional cephalic fin. This small, demographically independent population appears vulnerable to the impacts from non-target fisheries, primarily from entanglement in fishing line, and could suffer from exploitation by commercial, unregulated 'swim-with manta ray' programs. Management on an island-area basis is recommended.

The size and structure of a photographically identified population of reef manta ray, Manta alfredi, were examined at aggregation sites over a four-year period in southern Mozambique. The use and standardisation of photo-ID techniques was examined as a minimally-intrusive means to study this species. Using these techniques, we report on the size, structure and seasonality of this population of M. alfredi. In total, 449 individuals were identified during this time period, 40.5% of which were re-sighted on at least one occasion. The longest period between re-sighting events was 1,252 days. During the study period, annual population size estimates for M.alfredi ranged from 149 to 454 individuals. The superpopulation size estimate for the entire study period was 802 individuals, the first reported for M. alfredi at a monitored aggregation site. A highly significant sex bias was evident with a female:male ratio of 3.55:1. The majority of rays (89.9% males; 49.7% females) were considered mature, with most individuals between 3.0 and 4.9 m in disc width. Manta alfredi were observed at the study sites in each month of the calendar year. The maximum number of individual rays seen per dive was 30. Large numbers of rays (20 + per dive) were seen in the months of November, December and January, which coincide with the breeding season. Natural markings were unique to individuals and did not change substantially with time, which provided further support for their use in the identification of individual M. alfredi over multiple years. Multiple re-sightings of individual M. alfredi suggest that many individuals in this population exhibit site fidelity to the examined aggregation sites. As target subsistence fishing for M. alfredi exists along the Mozambican coastline, management efforts to monitor and prevent overexploitation at these critical habitats should be a priority.

The Republic of Maldives in the central Indian Ocean is home to large numbers of manta rays, Manta alfredi. They are known to undertake seasonal migrations within the Maldives, but these movements have not been well documented. The aims of this study were to map the seasonal distribution of manta rays within the Maldives, and to provide some indications of the physical and biological oceanographic processes affecting their distribution. The seasonal distribution of mantas was determined from a national survey of fishermen, interviews with experienced divers and personal observations. The data demonstrate that the distribution of mantas is strongly influenced by the seasonally reversing monsoon currents. Mantas occur on the downstream sides of the atolls, and are rare on the upstream sides, switching sides biannually as the monsoon currents change direction. These seasonally alternating currents are driven by monsoon winds which also alternate according to the season, and bring clear oceanic water to the upstream sides of the atolls. As the currents pass over the Maldives ridge, nutrient-rich waters are lifted to the surface, promoting phytoplankton blooms (as demonstrated by the distribution of chlorophyll-a) on the downstream sides of the atolls. This manifestation of the island mass effect supports an abundance of zooplankton, which in turn supports the manta rays.

Shark bite injuries on reef manta rays Manta alfredi off the coast of Inhambane, Mozambique, were examined over a three-year period (2003–2006). The frequency and seasonality of attacks, the rate of wound healing, and the possible identities of attackers were explored. This study presents the first examination of bite wounds on manta rays in the wild and the role sharks may play in the natural mortality of this species. The reported incidence of shark-inflicted injuries is high with over three-quarters of the sampled population affected. In total, 571 bite injuries were observed on 283 identified individuals. The number of bite injuries varied from one to seven, with a mean of 1.54 bite wounds. There was no significant difference in the frequency of bite injuries in male and female rays. The majority (96%) of the observed bite wounds were healed. Fresh wounds occurred throughout the year, with no obvious seasonality. The bull shark Carcharhinus leucas and tiger shark Galeocerdo cuvier are suggested as the...

Despite the worldwide distribution of manta ray (Manta alfredi) in tropical and subtropical regions, there is very little published information on their biology or ecology. Knowledge of the abundance of mantas and their migration patterns is essential for conservation, and the first stage in any study is a method to identify individuals. The purpose of this paper is to present a method of visual identification of individuals of manta which can be used at any site where mantas are regularly observed. In mantas, each individual has a characteristic pattern of dark markings on the ventral side. The most important individual identifying marks are patterns of ovals in the area between the gill slits, supported by distinctive patterns of mottles and spots in the lower abdominal area (posterior to the gill slits) and areas of dark pigmentation around the head and posterior wing margins. Significant changes in ventral makings have not been observed in observation periods exceeding 5 years. Scars and miss...

Morphometrics are useful for describing and managing animal populations, but mea- surements can be difficult to obtain, especially on large free-ranging aquatic animals. The accuracy and precision of paired-laser photogrammetry were tested as a simple and non-invasive remote sens- ing system for measuring the body size of free-ranging, resident manta rays Manta alfredi, a newly described species that is poorly understood. Based on repeated measurements of a pipe of known size, the paired-laser system proved accurate (mean error of 0.39%) and precise (CV = 0.54%). Repeated measurements on 154 different manta rays visiting a cleaning station off Maui, Hawaii, produced a mean CV of 1.46%. Disc length (DL) measurements were more precise than disc width (DW) measurements, and an empirically derived disc ratio (DR) function was applied to convert DL to DW measurements for standard comparison with other studies. Sexual dimorphism was present with the largest female (3.64 m DW) 18% larger than the largest male (3.03 m DW). Sexual maturity in females, based on evidence of pregnancy and mating scars, was conservatively determined to be 3.37 m DW. The DW at which 50% of the males were likely to be mature (based on clasper length) was between 2.7 and 2.8 m. The absence of individuals < 2.5 m DW suggests that age class segrega- tion occurs in this population. Paired-laser photogrammetry proved to be a simple, non-invasive, accurate, and precise method for sizing free-ranging manta rays. Repeated measurements on known individuals over time could provide population growth parameters needed for adequate manage- ment of this poorly understood species.

The taxonomic history of the genus Manta has been questionable and convoluted, with Manta having one of the most extensive generic and species synonymies of any living genus of cartilaginous fish. Having previously been considered a monotypic genus with a single recognized species, Manta birostris (Walbaum 1792), new evidence, in the form of morphological and meristic data, confirm that two visually distinct species occur, both with wide ranging distributions through many of the world’s oceans. Manta birostris stands as the most widely distributed member of the genus, while Manta alfredi (Krefft 1868), resurrected herein, represents a smaller, more tropical species. Separation of the two species is based on morphometric measurements and external characters including colouration, dentition, denticle and spine morphology, as well as size at maturity and maximum disc width. The two species of Manta are sympatric in some locations and allopatric in other regions. A visual key was constructed which highlights the conspicuous, diagnostic features of the two species using data collected throughout their respective geographical ranges. A third, putative species, referred to here as Manta sp. cf. birostris, in the Atlantic may be distinct from M. birostris, but further examination of specimens is necessary to clarify the taxonomic status of this variant manta ray. The results of this study will aid in the differentiation of members of this genus both in the field and in preserved specimens. The splitting of this long-standing monospecific genus will help to highlight the specific threats facing the different species of Manta (e.g. targeted fishing, bycatch fisheries, boat strikes and habitat degradation) and will ultimately assist in the correct assessment of their respective worldwide conservation status.

Despite their large size and frequent occurrence in near-shore tropical habitats, little published information is available on the movements and behaviors of the giant manta ray, Manta birostris, and what factors influence visitation patterns. To examine the movements of manta rays in the Komodo Marine Park, Indonesia, an acoustic array was installed at up to seven sites in the park between 2000 and 2003. A total of 41 acoustic tags were deployed in three separate deployments in 2000, 2001 and 2002. Mantas were recorded in the park for up to 526 days with an average duration of 183 ± 136 days, when mantas made from 3 to 303 individual visits to different sites (median 58 visits). There was a clear preference for three sites that comprised over 90% of manta activity. The most popular site (German Flag) was off the southern tip of Komodo Island in an area with a high degree of bathymetric structure. Examination of the longest records suggests some site preference with 5 of 7 individuals spending greater than 90% of their time at the location where they were tagged. Using a general linear model it was possible to examine the effects of daytime, lunar phase, aggregation site, season and tidal phase on visitation patterns. The vast majority of visits were recorded during daylight hours at all sites. The strongest effects of both the lunar and tidal phase were apparent in the northern sites with the most visits occurring when tidal intensity was the greatest during full and new moons. The strongest seasonal pattern was observed in the south where no mantas were recorded during the first quarter in any year. This coincides with an increase in temperature and reduction of productivity in this region associated with monsoonal shifts. The long-term fidelity indicates that marine-protected areas centered around aggregation sites could help protect this species from overexploitation.

An analysis of 79 underwater photographs of Manta birostris gathered over a period of nine years in a marine protected area in southeastern Brazil suggests a high predictability of manta ray occurrences in the region during the austral winter (June–September). The reasons for this are probably related to the seasonal oceanographic conditions, as characterized by the presence of a coastal front at the study site in winter and consequent plankton enrichment, which provides a feeding opportunity for manta rays. In addition, a melanistic individual in the Atlantic Ocean that is similar in color to the Pacific Ocean’s “black manta” is reported for the first time.

© 2014 Elsevier Inc. Manta and devil rays are an iconic group of globally distributed pelagic filter feeders, yet their evolutionary history remains enigmatic. We employed next generation sequencing of mitogenomes for nine of the 11 recognized species and two outgroups; as well as additional Sanger sequencing of two mitochondrial and two nuclear genes in an extended taxon sampling set. Analysis of the mitogenome coding regions in a Maximum Likelihood and Bayesian framework provided a well-resolved phylogeny. The deepest divergences distinguished three clades with high support, one containing Manta birostris, Manta alfredi, Mobula tarapacana, Mobula japanica and Mobula mobular; one containing Mobula kuhlii, Mobula eregoodootenkee and Mobula thurstoni; and one containing Mobula munkiana, Mobula hypostoma and Mobula rochebrunei. Mobula remains paraphyletic with the inclusion of Manta, a result that is in agreement with previous studies based on molecular and morphological data. A fossil-calibrated Bayesian random local clock analysis suggests that mobulids diverged from Rhinoptera around 30 Mya. Subsequent divergences are characterized by long internodes followed by short bursts of speciation extending from an initial episode of divergence in the Early and Middle Miocene (19-17 Mya) to a second episode during the Pliocene and Pleistocene (3.6 Mya - recent). Estimates of divergence dates overlap significantly with periods of global warming, during which upwelling intensity - and related high primary productivity in upwelling regions - decreased markedly. These periods are hypothesized to have led to fragmentation and isolation of feeding regions leading to possible regional extinctions, as well as the promotion of allopatric speciation. The closely shared evolutionary history of mobulids in combination with ongoing threats from fisheries and climate change effects on upwelling and food supply, reinforces the case for greater protection of this charismatic family of pelagic filter feeders.

Recent successful efforts to increase protection for manta rays has highlighted the lack of basic ecological information, including vertical and horizontal movement patterns, available for these species. We deployed pop-up satellite archival transmitting tags on nine reef manta rays, Manta alfredi, to determine diving behaviors and vertical habitat use. Transmitted and archived data were obtained from seven tagged mantas over deployment periods of 102–188 days, including three recovered tags containing 2.6 million depth, temperature, and light level data points collected every 10 or 15 seconds. Mantas frequented the upper 10 m during daylight hours and tended to occupy deeper water throughout the night. Six of the seven individuals performed a cumulative 76 deep dives (>150 m) with one individual reaching 432 m, extending the known depth range of this coastal, reef-oriented species and confirming its role as an ecological link between epipelagic and mesopelagic habitats. Mean vertical velocities calculated from high-resolution dive data (62 dives >150 m) from three individuals suggested that mantas may use gliding behavior during travel and that this behavior may prove more efficient than continuous horizontal swimming. The behaviors in this study indicate manta rays provide a previously unknown link between the epi- and mesopelagic layers of an extremely oligotrophic marine environment and provide evidence of a third marine species that utilizes gliding to maximize movement efficiency.

On 11 July 1997, the mating behavior of wild manta rays,Manta birostris, was observed while skin diving off Chichijima. Ogasawara Islands, Japan, and recorded with 49 underwater photographs and about 20 minutes of video tape. The female manta ray involved was estimated as being approximately 5 m in dise width (DW) and the two males involved, approximately 4 m DW. Copulatory behavior of the two males appeared to be almost the same, copulation itself being of the abdomen-to-abdomen type. Initially, the males chased the female for 20–30 minutes, all animals swimming at approximately 10 km/h. Each copulation event occurred within one meter of the surface, during which time the participating male grasped the tip of the female's left pectoral fin with his mouth. The clasper was inserted for 90 seconds (Male No. 1) and 60 seconds (Male No. 2), respectively. The mating behavior sequence of the manta rays involved following five steps. 1.: Male chases behind the tail of the female, attempting (several times) to grasp the latter's pectoral fin (chasing behavior). 2.: Male bites the tip of the female's pectoral fin, before positioning itself against the latter's underside (biting behavior). 3.: Male inserts a clasper into the cloaca of the female (copulating behavior). 4.: Male removes the clasper from the cloaca of the female, but continues biting the latter's pectoral fin (post-copulating behavior). 5.: Male releases the pectoral fin of the female, setting her free (separating behavior).

Following a recent taxonomic revision, two manta species (Manta alfredi and Manta birostris ) have been advocated based on meristic and morphological characteristics (Marshall et al. 2009). Subsequent genetic analyses of the two species using mitochondrial and nuclear markers confirmed two distinguishable genetic groups (Kashiwagi et al. 2012). Using the above taxonomic and genetic criteria, we provide evidence for the first record of a living Manta alfredi ×Manta birostris hybrid. The Manta individual (Fig. 1a, b) was non-lethally sampled from a known manta aggregation site in Dunganab Bay, Sudan, Red Sea, in October 2012. The individual was identified in the field as Manta alfredi based on distinguishing morphological criteria: dorsoventral colouration/spot patterns, mouth and pectoral fin colouration, and absence of remnant spine (Fig. 1b; Marshall et al. 2009). DNA was recovered from a fin clip using standard molecular genetic protocols. The mitochondrial gene ND5 (1,154 bp) and nuclear gene RAG1 (646 bp) were amplified following Kashiwagi et al. (2012), and sequenced. Recovered sequences (GenBank accession nos. KF574269-KF574270) were aligned with those previously reported (Kashiwagi et al. 2012) and a haplotype network was constructed in TCS 1.21 (Clement et al. 2000). TheManta specimen was confirmed to carry a newManta alfredi mtDNA haplotype (red in Fig. 1). However, the RAG1 sequence indicates that this individual is an interspecific hybrid. The twoManta species are reciprocally monophyletic at the RAG1 locus, which contains two species-specific single nucleotide polymorphisms (SNPs): at position 73 (M . alfredi : G; M . birostris : A) and position 507 (M . alfredi : A; M . birostris : C) following Kashiwagi et al. (2012). The hybrid individual is heterozygous at both SNPs (see inset chromatograms). Heterozygosity was confirmed by sequencing this individual in triplicate in both forward and reverse directions at RAG1 . Our finding indicates that reproductive isolation among M . alfredi and M . birostris may be less complete than previously thought, or alternatively, that species-specific taxonomic and genetic differentiation is not as unambiguous as currently suggested. Given the designation of the two discrete species as vulnerable on the IUCN Red List and their recent listing on CITES appendix II following concern over increasing global R. P. Walter (*) : S. T. Kessel :A. T. Fisk :D. D. Heath : N. E. Hussey University of Windsor – GLIER, Windsor, Canada e-mail: rwalter@uwindsor.ca

Assessing the trophic role and interaction of an animal is key to understanding its general ecology and dynamics. Conventional techniques used to elucidate diet, such as stomach content analysis, are not suitable for large threatened marine species. Non-lethal sampling combined with biochemical methods provides a practical alternative for investigating the feeding ecology of these species. Stable isotope and signature fatty acid analyses of muscle tissue were used for the first time to examine assimilated diet of the reef manta ray Manta alfredi, and were compared with different zooplankton functional groups (i.e. near-surface zooplankton collected during manta ray feeding events and non-feeding periods, epipelagic zooplankton, demersal zooplankton and several different zooplankton taxa). Stable isotope δ(15)N values confirmed that the reef manta ray is a secondary consumer. This species had relatively high levels of docosahexaenoic acid (DHA) indicating a flagellate-based food source in the diet, which likely reflects feeding on DHA-rich near-surface and epipelagic zooplankton. However, high levels of ω6 polyunsaturated fatty acids and slightly enriched δ(13)C values in reef manta ray tissue suggest that they do not feed solely on pelagic zooplankton, but rather obtain part of their diet from another origin. The closest match was with demersal zooplankton, suggesting it is an important component of the reef manta ray diet. The ability to feed on demersal zooplankton is likely linked to the horizontal and vertical movement patterns of this giant planktivore. These new insights into the habitat use and feeding ecology of the reef manta ray will assist in the effective evaluation of its conservation needs.

The preserved stomach contents from the manta ray, collected in 1935, that provided the basis for the 2009 taxonomic resurrection of the species Manta alfredi, were examined. The majority of the material comprised calanoid copepods (61.7%) and trypanorhynch cestodes (34.6%), with minor contributions by arrow worms, a barnacle larva and a nematode. Comparison of the size-frequency distributions of stomach contents with that of zooplankton from the Great Barrier Reef region suggest that this manta ray preferentially ingested large copepods, or that the filter mechanism used to extract prey from the water was selective for prey items over 0.8mm in length. This is the first description of the diet of M. alfredi from stomach contents, and is consistent with previous inferences about what this species consumes.

As manta rays face increased threats from targeted and bycatch fisheries, manta ray watching tourism, if managed properly, may present an attractive economic alternative to consumptive use of these species. Both species in the genus Manta (Manta alfredi and Manta birostris) are classified by the International Union for the Conservation of Nature Red List as species Vulnerable to extinction in the wild, and are considered unsustainable as fisheries resources due to their conservative life history characteristics, which considerably reduce their ability to recover population numbers when depleted. Utilising dive operator surveys, Internet research, and a literature review, this study provides the first global estimate of the direct economic impact of manta ray watching tourism and examines the potential socio-economic benefits of non-consumptive manta ray watching operations relative to consumptive use of manta rays as a fishery resource. In the 23 countries in which manta ray watching operations meeting our criteria were identified, we estimated direct revenue to dive operators from manta ray dives and snorkels at over US$73 million annually and direct economic impact, including associated tourism expenditures, of US$140 million annually. Ten countries account for almost 93% of the global revenue estimate, specifically Japan, Indonesia, the Maldives, Mozambique, Thailand, Australia, Mexico, United States, Federated States of Micronesia and Palau. In many of the areas where directed fisheries for manta rays are known to occur, these activities overlap with manta ray tourism sites or the migratory range of the mantas on which these sites depend, and are likely to be unsustainable and detrimental to manta ray watching tourism.

The fishery for mobulid rays, also known as devil rays, has been practiced in the Bohol Sea for over a century yet very little is known about its history and characteristics. This study provides the first detailed description of the mobulid ray fishery in the Bohol Sea, Philippines. It describes the history and evolution of the fishery from the 19th century to 2013. It characterizes the fishery based on the species targeted, gears used, the organization, catch distribution, processing, monetary value, and the market of its by-products. This paper also analyses the changes that occurred through time, the management of the fishery and the drivers of the fishery. A multi-disciplinary approach was employed by combining ethno-historical research methods and catch landing monitoring in four primary sites within the Bohol Sea. This fishery began as an artisanal fishery using sail and row boats equipped with harpoons and gaff hooks practiced in at least four coastal villages in Bohol, Camiguin and Limasawa. The fishing fleet has decreased since the beginning of the 20th century however, with the motorization of the fishery and shift to the use of gillnets, the extent of the fishing grounds and market of the products have expanded. Four species of mobulid rays are caught in the Bohol Sea: Manta birostris, Mobula japanica, Mobula thurstoni and Mobula tarapacana. A fifth species, targeted by a fishing community off Dinagat as an off-shoot of the Bohol fishery is most likely the Manta alfredi. Currently, the fishery for mobulids is centered in Bohol Province where it has been practiced longest. The monetary value of mobulids in this region has increased and the dependence of fishing communities for their livelihood is significant. The unique characteristics of this fishery and the socio-cultural context within which it operates merits a thorough investigation in order to design the appropriate management strategy.

For species which bear unique markings, such as natural spot patterning, field work has become increasingly more reliant on visual identification to recognize and catalog particular specimens or to monitor individuals within populations. While many species of interest exhibit characteristic markings that in principle allow individuals to be identified from photographs, scientists are often faced with the task of matching observations against databases of hundreds or thousands of images. We present a novel technique for automated identification of manta rays (Manta alfredi and Manta birostris) by means of a pattern-matching algorithm applied to images of their ventral surface area. Automated visual identification has recently been developed for several species. However, such methods are typically limited to animals that can be photographed above water, or whose markings exhibit high contrast and appear in regular constellations. While manta rays bear natural patterning across their ventral surface, these patterns vary greatly in their size, shape, contrast, and spatial distribution. Our method is the first to have proven successful at achieving high matching accuracies on a large corpus of manta ray images taken under challenging underwater conditions. Our method is based on automated extraction and matching of keypoint features using the Scale-Invariant Feature Transform (SIFT) algorithm. In order to cope with the considerable variation in quality of underwater photographs, we also incorporate preprocessing and image enhancement steps. Furthermore, we use a novel pattern-matching approach that results in better accuracy than the standard SIFT approach and other alternative methods. We present quantitative evaluation results on a data set of 720 images of manta rays taken under widely different conditions. We describe a novel automated pattern representation and matching method that can be used to identify individual manta rays from photographs. The method has been incorporated into a website (mantamatcher.org) which will serve as a global resource for ecological and conservation research. It will allow researchers to manage and track sightings data to establish important life-history parameters as well as determine other ecological data such as abundance, range, movement patterns, and structure of manta ray populations across the world.

We conducted an ultrasonographic experiment on a pregnant manta ray, Manta alfredi (Chondrichthyes, Batoidea). This study showed how the embryo of the live-bearing elasmobranchs respires in the body of the female. In the embryonic stage, the manta ray embryo takes in uterine fluid by buccal-pumping. After birth, the manta ray shifts its respiratory mode from buccal-pumping to ram-ventilation. The rapid reduction of the spiracle size in the young manta ray may reflect this shift of respiratory mode. Unlike mammals or some carcharhinid sharks that acquire oxygen through a placenta and umbilical cord, the manta ray embryo does not have a direct connection with the mother. Thus, the manta ray embryo obtains oxygen by buccal-pumping of the uterine fluid, in the same way that the embryos of egg-laying species obtain oxygen from the water in the egg case. This finding extends our understanding of the diversity of embryonic respiratory systems in live-bearing vertebrates.