Sawfishes, Guitarfishes, Skates and Rays: Part 2

LEVANTAMENTO DAS ESPÉCIES DE ELASMOBRÂNQUIOS CAPTURADOS POR APARELHOS-DE-PESCA QUE ATUAM NO BERÇÁRIO DE CAIÇARA DO NORTE (RN)Survey of elasmobranch species caught by fishing gears that operate on the nursery ground of Caiçara do Norte, Rio Grande do Norte State

Article

Nov 2008

A proteção de áreas de berçário é uma ferramenta eficaz para o recrutamento futuro de populações sob pressão pesqueira. Estas áreas costumam ocorrer em águas costeiras, protegidas e de alta produtividade, fornecendo uma ampla gama de itens alimentares e a atenuação do risco de predação, condições para que os jovens cresçam rápido e se juntem à parte adulta da população. A zona costeira de Caiçara do Norte (RN) é considerada como berçário primário e/ou secundário para 12 espécies de elasmobrânquios: Gymnura micrura, Dasyatis guttata, Rhinobatos cf percellens, Narcine brasiliensis, Aetobatus narinari, Dasyatis americana, Rhinopterasp. e Manta birostris , entre as raias, e Rhizoprionodon porosus, Carcharhinus acronotus, C. falciformis e C. limbatus , entre os tubarões. Ocorrem ainda jovens dePrionace glauca, Ginglymostoma cirratum e C. signatus. O presente estudo teve como proposta descrever as artes de pesca que capturam elasmobrânquios nessa região, através de amostragens quinzenais durante o período de janeiro a julho de 2008, com o acompanhamento da frota artesanal que possibilitou um total de 1.043 indivíduos de seis espécies de raia e quatrode tubarão.

Pelvic fin musculature in skates: Morphological variation, phylogeny, and locomotor implications (Chondrichthyes: Batoidea: Rajiformes)

Article

Full-text available

Apr 2022
ANAT REC

Karla Soares

Skates of the order Rajiformes are known to perform benthic locomotion by using their specialized bilobed pelvic fins and thus walking or punting on the substrate. Several studies have investigated the pelvic fin and girdle skeleton but little is known about the muscles responsible for walking performance. The goals of this study, therefore, are to investigate, describe, and illustrate the morphological variation in pelvic musculature among skate species and to discuss the phylogenetic and locomotor implications of the conditions observed. Specimens belonging to 19 of the 36 skate genera currently valid for the order Rajiformes were manually dissected and specimens of Narcine, Tetronarce, and Zapteryx were also examined as comparative material. The pelvic musculature varies among skates, mainly regarding the extension of ventral and dorsal muscles related to the anterior lobe of pelvic fin. All rafijorms examined and the torpediniforms Narcine and Tetronarce possess a complex pelvic musculature associated to the anterior pelvic lobe, which is herein suggested as a synapomorphy of Batoidea with independent losses in guitarfishes and stingrays. Nevertheless, the examination of additional taxa is required to better understand the evolution of pelvic musculature within batoids. The morphological variation observed could indicate different walking abilities as discussed herein but further studies on the locomotion behavior in skates are needed to confirm these assumptions.

Reproductive biology of the whitespotted eagle ray Aetobatus narinari (Myliobatiformes) captured in the coast of Paraíba and Pernambuco, Brazil

Article

Full-text available

Mar 2022
J FISH BIOL

The present study analysed aspects of reproductive biology based on macroscopic and microscopic structures of whitespotted eagle ray Aetobatus narinari captured by artisanal fishing off the coast of Paraíba and Pernambuco (7° 30′ S, 34° 49′ W; 7° 47′ S, 34° 51′ W), northeast Brazil. Of the 71 individuals in the sample, 55% were female (disc width – WD: 532–1698 mm) and 45% were male (WD: 442–1410 mm). The body size at which 50% of the individuals are mature (WD50) for males was 1155.8 mm; the clasper length varied between 24 and 184 mm. The WD50 for females was 1293.9 mm; the diameter of the largest vitellogenic follicle varied between 11 and 31 mm; and only the left ovary and uterus were functional. The microanatomy of the reproductive tract of males and females agrees with that of other elasmobranch species. In males, the highest hepato‐somatic index (IH) average and gonado‐somatic index (IG) average occurred in the third bimester of the year, whereas in females the highest values (average IH and IG, respectively) were in the second bimester of the year. Based on the information on reproduction of A. narinari from this study, it will be possible to contribute to the correct management and protection of this species.

Molecular evidence supporting the expansion of the geographical distribution of the Brazilian cownose ray Rhinoptera brasiliensis (Myliobatiformes: Rhinopteridae) in the western Atlantic

Article

Full-text available

Nov 2017

The genus Rhinoptera is composed of eight species widely distributed in tropical, subtropical and temperate coastal waters, which inhabit bays, estuaries and river mouths. Cownose ray Rhinoptera bonasus has been reported to inhabit the Western Atlantic including the Gulf of Mexico and the Caribbean, whereas the Brazilian cownose ray R. brasiliensis has been considered endemic to the coast of Brazil. Recent reports of R. brasiliensis in the Gulf of Mexico bring about the question of whether the species has a wider range than previously reported. Here, the mitochondrial genes COI, Cytb, NADH2 and the nuclear gene RAG1 were used to distinguish among species and to confirm the presence of R. brasiliensis in the Gulf of Mexico. R. brasiliensis specimens collected along the southern Gulf of Mexico showed a remarkable genetic and morphological affinity when compared with R. brasiliensis specimens from Brazil, supporting the presence of the species in Mexico (from Veracruz through Campeche) and providing evidence that its distribution ranges from Brazil to the Caribbean Sea and the Gulf of Mexico. Both species overlap geographically to a large degree, leading to a reassessment of their conservation status. Our results also show that R. bonasus distribution in the Gulf of Mexico may be restricted to the northern portion, in US waters.

Morphological conservation of rays in the genus Rhinoptera (Elasmobranchii, Rhinopteridae) conceals the occurrence of a large batoid, Rhinoptera brasiliensis Müller, in the northern Gulf of Mexico

Article

Jul 2017
ZOOTAXA

In 2007, three rays identified as Rhinoptera brasiliensis based on tooth series counts were captured in the northern Gulf of Mexico, a region far outside their accepted range of the coastal waters of southern Brazil. Genetic analyses confirmed that these individuals were distinct from R. bonasus, the only recognized indigenous rhinopterid in the Gulf of Mexico. Further analyses of over 250 specimens confirmed the widespread occurrence of two species in the northern Gulf of Mex-ico and revealed that the anomalous individuals related most closely to vouchered specimens of R. brasiliensis from Bra-zil. Discriminant function analyses of morphological data identified several potential discriminating characters, but the degree of overlap of the measurements and counts between the two species rendered most impractical for identification purposes. However, the shape of the supracranial fontanelle appeared to be consistently reliable in differentiating between the two species. Tooth series counts (R. bonasus = 5 to 15, R. brasiliensis = usually 7 to 13) were significantly different between the two species but exhibited considerable overlap. This is the first study to verify the occurrence of R. brasilien-sis in the northern Gulf of Mexico; however, the close genetic relationships to other rhinopterid species, as well as the morphological similarity of the group as a whole, require additional research.

A new subfamily, Styracurinae, and new genus, Styracura, for Himantura schmardae (Werner, 1904) and Himantura pacifica (Beebe & Tee-Van, 1941) (Chondrichthyes: Myliobatiformes)

Article

Full-text available

Oct 2016

A new subfamily (Styracurinae, subfam. nov.) and genus (Styracura, gen. nov.) are erected for Trygon schmardae Werner, 1904 (type species) and Dasyatis pacificus Beebe & Tee-Van, 1941, species placed in Himantura Müller & Henle, 1837 since 1953 but which differ significantly from it and all dasyatid genera in many morphological features. Recent molecular phylogenetic hypotheses based on the entire protein-coding mitochondrial genome have recovered Styracura as the sister group of the Neotropical freshwater stingrays (Potamotrygonidae), agreeing with previous morphological and molecular phylogenies. The Styracurinae, subfam. nov., is therefore placed in the Potamotrygonidae to reflect the current phyloge-netic view. Morphological characters of phylogenetic relevance of the dermal denticles, ventral lateral-line canals, hyoid arch, cranial musculature, and pectoral and pelvic girdles are discussed and compared to other stingrays, in particular to dasyatids and potamotrygonins (now ranked as a subfamily). Inferred derived characters of Styracura and potamotry-gonins require homoplasy (they are absent from Paratrygon and Heliotrygon), and ventral lateral-line canal patterns and morphology of the scapular process and pelvic girdle generally reveal an affinity to different dasyatid genera, but one most likely based on plesiomorphies or independent evolution; Styracura is considered more closely related to potamotry-gonins.

Population ecology and biology of the reef manta ray Manta alfredi in eastern Australia

Thesis

Full-text available

Jun 2013

Lydie I. E. Couturier

Mobulid rays (family Mobulidae) are epipelagic zooplanktivores separated into two genera, Manta (2 species) and Mobula (9 species). Despite their economic importance in the tourism industry, mobulid rays currently face severe fisheries pressures worldwide which threatens the survival of many populations. These rays are considered long-lived and have low fecundity, which make them particularly vulnerable to fisheries exploitation. The paucity of data on the ecology and biology of these species has hindered the ability to effectively assess their conservation status and needs. Available information on mobulid species in peer-reviewed and grey literature was reviewed in this study to identify the critical knowledge gaps on their biology, ecology and conservation. The current lack of baseline data on mobulid species relates to the inherent challenges associated with studying large, wide-ranging pelagic animals. Manta rays (Manta spp.) predictably aggregate at particular sites where they can be easily approached by divers. These aggregation sites provide unique opportunities for scientists to investigate population dynamics of these otherwise elusive species. This thesis examined the population of the reef manta ray Manta alfredi off eastern Australia at several aggregation sites. The reef manta ray is the most common mobulid species encountered in east Australian waters and, although the species is a popular tourist attraction, information on its population biology and ecology was non-existent in this part of the world prior to this study. Photographic identification techniques were used to identify individual reef manta rays at eight sites along the coast between Osprey Reef, northern Great Barrier Reef, Queensland and the Solitary Island Marine Park, New South Wales. A total of 716 individuals were identified between 2007 and 2012, including 636 at Lady Elliot Island (LEI), southern Great Barrier Reef. Over 60% of individuals identified along this coastline were resighted at least once between 2007 and 2012 and the mean number of sightings per individual was 3. The sex ratio of this population was significantly biased toward females with an overall 1.3:1 female-to-male ratio observed. Reef manta rays are present all year around at LEI, although they are seen in higher numbers in winter, whereas they are mainly seen off North Stradbroke Island and Byron Bay from mid-spring to mid-autumn. Seasonal movements were observed between these locations with 56 individuals identified at both LEI and North Stradbroke Island (c. 380 km to the south), 12 at LEI and Byron bay (c. 500 km to the south) and one at LEI and North Solitary Island (c. 650 km to the south). Robust design population models were used to estimate the population size of the winter aggregation at LEI over a four-year period using the program MARK. The model estimated up to 532 individuals in the population within one winter season and that survivorship of reef manta rays between consecutive iii years was exceptionally high (φ=1). This abundance estimate is the largest assessed for a seasonal aggregation of reef manta rays at a single site. The superpopulation size estimate of this winter aggregation at LEI was 601 individuals over the 4-year study period. This study demonstrated that the habitat around LEI forms a key aggregation site for a large portion of the reef manta ray population in east Australian waters. Passive acoustic telemetry techniques were used to examine the residency and site fidelity patterns of the reef manta ray at LEI. Five acoustic receivers were moored around the island between June 2009 and September 2012 and a total of 33 acoustic transmitters were deployed on reef manta rays. All tagged animals returned to this site within their recorded period with some individuals visiting the area for up to 23 consecutive days. Using a general linear mixed effects modelling approach, we analysed the hourly visitation patterns of manta rays with respect to environmental and temporal parameters. Diel phase, wind direction, month, wind speed and moon phase all had significant effects on the presence of manta rays at LEI. Individuals were significantly more likely to be present during daytime and in calmer weather conditions, which may be linked with behavioural thermoregulation and cleaning activities. A strong seasonal pattern was detected with more individuals present in winter around LEI. Sea temperature was not directly linked with this pattern. It is hypothesised that food availability may be a key parameter for this seasonal aggregation. The high degree of site fidelity of some individuals at LEI underpins the importance of this site as a key habitat for reef manta rays. Stable isotope and fatty acid signature analyses were conducted on reef manta ray muscle tissue biopsy samples to examine the species’ assimilated diet. Muscle tissue δ15N and δ13C values, and the fatty acid signature were compared to those derived from 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). A trophic position estimate of three was derived from stable isotope δ15N values, and the relatively high levels of the fatty acid trophic marker 18:1ω9 (>13% of total fatty acids) confirmed that the reef manta ray is a secondary consumer. Near-surface and epipelagic zooplankton fatty acid composition indicated a dominant flagellate-based food source with high levels of docosahexaenoic acid (>20% of total fatty acids). The reef manta ray had relatively high levels of docosahexaenoic acid (>10% of total fatty acids) also indicating a flagellate-based food source in the diet. High ω6 fatty acid levels (>17% of total fatty acids) and slightly enriched δ13C values (-17.3‰) in reef manta ray tissue suggest that the species does not feed predominantly on near surface pelagic zooplankton, but obtains a major part of its diet from another source. The closest match is with demersal zooplankton, suggesting it is an important part of the reef manta ray diet. The ability to feed on demersal zooplankton is likely linked to iv the horizontal and vertical movement patterns of the reef manta ray. 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 current study has expanded our knowledge of a regionally important population of the reef manta ray, and has provided new insights into key aspects of the species’ ecology. This thesis used a combination of methods based on practical and rigorous approaches and brings new perspectives to the study of wide ranging marine species. ‘Citizen science’ provided important empirical data on the longevity, site affinity, seasonal movement and distribution of the reef manta ray population along the eastern seaboard of Australia. Robust sampling design and appropriate population models were used to estimate the population size of a large annual aggregation of manta ray across several consecutive years. Acoustic telemetry data were analysed through an original statistical approach able to integrate individual behaviour of the tagged individuals. Non-lethal approaches were used to study the diet of reef manta rays and provided results that challenge key aspects of the current paradigm about the diet and feeding ecology of the species. These methods are replicable and will contribute to the standardisation of methodologies and modelling in mobulid species research.

Whitespotted eagle ray (Aetobatus narinari) age and growth in wild (in situ) versus aquarium-housed (ex situ) individuals: Implications for conservation and management

Article

Full-text available

Sep 2022

Elasmobranchs typically display slow growth, late maturity and low fecundity life history characteristics, making them vulnerable to fishing pressures and environmental perturbations. The whitespotted eagle ray (Aetobatus narinari), a large pelagic migratory ray with an endangered status on the IUCN Red List, fits this pattern based on available literature. Historically, age and growth parameters for this ray have been reported through vertebral ageing methods. However, the periodicity of vertebrate band pair formation, which is used for ageing, has not been validated for this species, making ageing accuracy and thus the resulting growth parameters uncertain. In this study, we used both a frequentist and Bayesian method of estimating sex-specific von Bertalanffy growth parameters (DW ∞, k) in wild recaptured versus aquarium-housed rays. Additionally, we estimated growth from repeated measurement data collected from aquarium-housed rays, as an alternative approach to obtain growth parameters while allowing for individual variability. Between 2009 and 2020, 589 whitespotted eagle rays were caught, measured, tagged and released along the southwest coast of Florida. Of these rays, 34 were recaptured between 5–1413 days at liberty. Nineteen additional rays were collected during the same period, transported and maintained at Georgia Aquarium, Atlanta, where they were regularly weighted and measured. Data from Association of Zoos and Aquariums accredited facilities provided prior information on maximum size for the Bayesian estimations, and size at birth, size at maturity, and maximum life span. These data were used to plot and interpret von Bertalanffy growth curves. Wild whitespotted eagle rays were found to grow faster and mature earlier than previously thought, with Bayesian estimates of k = 0.28 year⁻¹ in females, and k = 0.30 year⁻¹ in males. Aquarium-housed individuals seemed to grow slower and reach smaller sizes, although data provided by the aquariums showed variable growth patterns depending on the facility. Longevity was estimated at 14-15 years in wild rays while maximum lifespan observed in aquariums was 19-20+ years. Life history parameters and growth trajectories generated from this study offer valuable information to aid with future conservation management strategies of this endangered species.

Mulheres que pesquisam Elasmobrânquios e formam redes: as experiências do simpósio online ELASMulheres

Article

Full-text available

Jan 2022

The southernmost record and an update of the geographical range of the Atlantic chupare, Styracura schmardae (Chondrichthyes: Myliobatiformes)

Article

Full-text available

May 2020
J FISH BIOL

The present study established the southernmost distribution range for the Chupare stingray Styracura schmardae based on a specimen caught on the easternmost portion of Ceará State, northeastern Brazil. Identification was based on diagnostic morphological characters and molecular data (sequence of the mitochondrial DNA gene nd2; 1046 bp). This record expands the known distribution range for this species by more than 1200 km and confirms that S. schmardae is distributed in more than one biogeographical province. Significance statement There are few records of the Atlantic Chupare stingray for Brazil and most of them are associated with the Amazon River mouth. New records indicate that this species is also present in the South Atlantic portion of the Brazilian coast. Apparently having a low abundance throughout its range, these new records increase the range of occurrence of this species.

Seasonal aggregation and diel activity by the sicklefin devil ray Mobula tarapacana off a small, equatorial outcrop of the Mid-Atlantic Ridge

Article

Oct 2018
J FISH BIOL

The present study aimed to analyse occurrence patterns, relative abundance and habitat use by the sicklefin devil ray Mobula tarapacana in the Saint Peter and Saint Paul Archipelago (SPSPA), Brazil, located in the Mid-Atlantic Ridge. Sampling was conducted between December 2008 and December 2012 by surface surveys and tagging with conventional tags and acoustic transmitters. Mobula tarapacana were sighted in the SPSPA year round but the highest frequency of occurrence was observed from January to June, probably due to greater food availability during this season. However, M. tarapacana might also use the area for reproductive purposes based on evidence of mating behaviour. The residency period of tagged rays measured by three autonomous acoustic receivers deployed around SPSPA spanned from 1 to 74 days with most of the detections occurring during daytime. These results suggest that the SPSPA could be an ecologically-important aggregation area for M. tarapacana, possibly providing the species with a feeding or resting habitat while transiting in the equatorial Atlantic Ocean.

Southernmost record of the Giant Manta Ray Mobula birostris (Walbaum, 1792) in the Eastern Pacific

Article

Full-text available

Nov 2017

Background; Manta rays (Mobulidae), Mobula birostris and Mobula alfredi, are widely distributed in tropical and temperate waters. Still, little is known about their movements and their ecological interactions (e.g. behavior and diet). In Peru, M. birostris has only been reported along the northern shore within the Tropical East Pacific Marine Province. No official reports exist from central or south Peru within the Warm Temperate Southeastern Pacific Marine Province. Methods; On December 22nd 2015, a rare sighting of a ~4 m disc width mobulid ray was recorded as video footage near the Palomino Islets, Lima, Peru. ResultsIn situ observations and subsequent analysis of the footage confirmed that this single mobulid was a M. birostris with a melanistic color morph. Conclusions; This sighting could be explained by the warm El Niño, primary (chl-a), and secondary (zooplankton) productivity events during that same period. This represents the southernmost record of M. birostris in the southeastern Pacific (12°S) and the first report of this species in the Warm Temperate Southeastern Pacific Marine Province and in the Humboldt Current Large Marine Ecosystem.

Population Structure and Seasonal Migration of the Spotted Eagle Ray, Aetobatus narinari

Article

Full-text available

Mar 2015

Few studies have reported on the fine-scale population genetics of batoid species in the Atlantic basin. Here, we investigate the genetic diversity and population structure of the spotted eagle ray, Aetobatus narinari, sampled in the northeastern and southwestern parts of the Gulf of Mexico and in the northwestern Caribbean Sea. Samples were collected from 286 individuals sampled across 3 geographic localities. Estimates of divergence based on the mitochondrial cytochrome b gene and 10 nuclear microsatellite loci reveal weak but significant genetic structure among A. narinari populations in this region. Analysis of molecular variance estimates based on both marker types indicate significant differentiation between Florida and Mexico populations, while comparisons with Cuba suggest high levels of gene flow with rays from both Mexico and Florida. Conflicting results were found from the different marker types when sexes were analyzed separately underscoring the importance of applying multiple marker types when making inferences about population structure and sex-biased dispersal. Results from Bayesian clustering analyses suggest rays may be migrating south out of the Gulf of Mexico and into the northwestern Caribbean Sea. Given the impacts of fisheries on this species, coupled with the lack of population genetic data available, these findings offer valuable information to aid with conservation management strategies. © The American Genetic Association 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Spatial patterning of Manta birostris in United States east coast offshore habitat

Article

Mar 2012
APPL GEOGR

This study aims to identify patterns in spatial distribution of Manta birostris along American East Coast by analyzing presence data using a suite of geostatistical techniques. Analysis of data from 1979 to 2008 revealed that the spatial patterns exhibited by the M. birostris include a strong clustering zone off the North Carolina from (however, not all years are represented in that range), Virginia and Maryland coast. Their presence is high near the coastal shelf edge and along the edge of the Gulf Stream. The mix of warm water and high chlorophyll concentration throughout the year in the region seem to create an ideal environment for this clustering pattern. However, in seasons with warmer water temperature, manta rays spread further north and inshore, possibly to avoid competition for prey. The results of geographic weighted regression indicate the role of sea surface temperatures on Manta presence or absence off the main current of the Gulf Stream near North Carolina and Virginia. Knowledge of the spatial distribution of M. birostris can assist in further protecting the species especially from dangers of by-catch and habitat degradation.

Non-food uses of sharks in southern Bahia, Brazil

Article

Full-text available

Sep 2024

Sharks are a highly threatened group, and the threats these animals face also affect the cultural ways artisanal fisher communities interact with them. Consequently, local knowledge arising from human interactions with these animals also becomes threatened, as well as the potential of fisheries management through ethnoconservation. In this sense, this study examines the dynamics of shark use by fishers in northeastern Brazil. In 2012, data was collected through semi-structured interviews about shark uses applied to 65 traditional fishers who use sharks differently. The ways fishers use these fish are changing mainly because fishers informed an overall reduction in shark catches. Thus, the analysis of their uses comprises a historical-anthropological record, as specific interactions are quickly disappearing. Therefore, the variety of utilitarian connections and changes in shark use patterns over time reveal both ecologic and cultural extinction threats of the traditional shark fisheries in this area. We suggest implementing anthropological and biological studies that aim to contribute to the maintenance of the livelihoods of populations that interact with sharks and seek to guarantee the sustainable exploitation of these animals.

Revisión del estatus taxonómico de los Batomorphii fósiles de la cuenca Limón Sur, Costa Rica y descripción de una nueva especie de Dasyatidae Review of the taxonomic status of fossil Batomorphii from Southern Limon Basin, Costa Rica and description of a new species of Dasyatidae

Article

Full-text available

Dec 2021

A taxonomic review of the rays [Batoidea] faunal assemblage from the Locality of Alto Guayacán, initially described by Laurito (1999), was made, same that was recovered from sediments of the Uscari Formation. The reason for making such revision is the remarkable advance in the knowledge of the dentition and the phylogenetic relationships of the recent and fossil rays. This is complemented by the multiple investigations on fossil Chondrichthyes from southern Central America and the Caribbean that have undoubtedly revolutionized the fossil record of the region. Many of the new species, then described for the Southern Limón Basin, have been validated and recognized by the scientific community and registered in other locations. However, it was necessary to review some of the previous determinations, in order to have an updated taxonomic record. RESUMEN: Se procedió a hacer una revisión taxonómica de la fauna de rayas [Batoidea], descritas inicialmente por Laurito (1999) para la Localidad de Alto Guayacán, misma que fue recuperada de sedimentos de la Formación Uscari. La razón para hacer tal revisión, es el notable avance en el conocimiento que se tiene de la dentición y de las relaciones filogenéticas de las rayas actua-les y fósiles. Lo que se complementa con las múltiples investigaciones sobre Chondrichthyes fósiles del sur de América Central y el Caribe que sin duda han revolucionado el registro fósil de la región. Muchas de las especies nuevas, entonces descritas para la Cuenca de Limón Sur, han sido validadas y reconocidas por la comunidad científica y registradas en otras localidades. Sin embargo, se hacía necesario revisar algunas de las determinaciones previas, a fin de tener un registro taxonómico actualizado.

Reproductive cycles of the southern banded guitarfish Zapteryx xyster and the Velez ray Raja velezi caught as bycatch in a bottom-trawl fishery

Article

Full-text available

Mar 2021

The southern banded guitarfish, Zapteryx xyster, and the Velez ray, Raja velezi, are two endemic elasmobranchs in the eastern Tropical Pacific that are commonly caught by the bottom-trawl fishery. Reproductive cycles of these batoids were inferred from the hepatosomatic and gonadosomatic indexes (males and females) and the oviductal gland width and the yolk follicle diameter (females) of mature specimens collected along the Pacific of Costa Rica between 2010 and 2011. Z. xyster females have a partially defined annual cycle with one reproductive peak in June and July, with most neonates and gravid females occurring during December and January (beginning of the dry season). The gestation period of Z. xyster can range between four and six months; males are probably capable of mating continuously throughout the year. Females and males of R. velezi have a continuous reproductive cycle with no clear peaks. Management and conservation measures of these batoids should consider their reproductive ecology, which may be linked to the degree of vulnerability to fishing. Based on our findings, we recommend reducing fishing pressure when mating (June-July) and pupping (December-January) of Z. xyster occur. In contrast, a reduction of fishing pressure on previously identified nursery grounds of R. velezi in the southern Pacific of Costa Rica may benefit their population.

S-shaped versus V-shaped transfer functions for binary Manta ray foraging optimization in feature selection problem

Article

Full-text available

Sep 2021
NEURAL COMPUT APPL

Feature selection (FS) is considered as one of the core concepts in the areas of machine learning and data mining which immensely impacts the performance of classification model. Through FS, irrelevant or partially relevant features can be eliminated which in turn helps in enhancing the performance of the model. Over the years, researchers have applied different meta-heuristic optimization techniques for the purpose of FS as these overcome the limitations of traditional optimization approaches. Going by the trend, we introduce a new FS approach based on a recently proposed meta-heuristic algorithm called Manta ray foraging optimization (MRFO) which is developed following the food foraging nature of the Manta rays, one of the largest known marine creatures. As MRFO is apposite for continuous search space problems, we have adapted a binary version of MRFO to fit it into the problem of FS by applying eight different transfer functions belonging to two different families: S-shaped and V-shaped. We have evaluated the eight binary versions of MRFO on 18 standard UCI datasets. Of these, the best one is considered for comparison with 16 recently proposed meta-heuristic FS approaches. The results show that MRFO outperforms the state-of-the-art methods in terms of both classification accuracy and number of features selected. The source code of this work is available in https://github.com/Rangerix/MetaheuristicOptimization.

S-Shaped versus V-Shaped Transfer Functions for Binary Manta Ray Foraging Optimization in Feature Selection Problem

Preprint

Full-text available

May 2020

Feature selection (FS) is considered as one of the core concepts in the areas of machine learning and data mining which immensely impacts the performance of classification model. Through FS, irrelevant or partially relevant features can be eliminated which in turn helps in enhancing the performance of the model. Over the years, researchers have applied different meta-heuristic optimization techniques for the purpose of FS as these overcome the limitations of traditional optimization approaches. Going by the trend, we introduce a new FS approach based on a recently proposed meta-heuristic algorithm called Manta Ray Foraging Optimization (MRFO) which is developed following the food foraging nature of the Manta rays, one of the largest known marine creatures. As MRFO is apposite for continuous search space problems, we have adapted a binary version of MRFO to t it into the problem of FS by applying eight different transfer functions belonging to two different families: S-shaped and V-shaped. We have evaluated the eight binary versions of MRFO on 18 standard UCI datasets. Of these, the best one is considered for comparison with 16 recently proposed meta-heuristic FS approaches. The results show that MRFO outperforms the state-of-art methods in terms of both classification accuracy and number of features selected.

Reproductive biology and diet of the longtail butterfly ray Gymnura poecilura (Shaw, 1804) along western Bay of Bengal

Article

May 2020

The reproductive biology and diet of the longtail butterfly ray Gymnura poecilura is described based on 630 specimens (N = 377 females and 253 males). The mean disc width ( WD ) of females and males was 576.7 mm (range = 190–920 mm) and 416.3 mm (230–550 mm), respectively. Sexual dimorphism in size was seen, with the maximum size of males being only 60% of the maximum female size. The disc widths at 50% maturity ( WD50 ) were estimated to be 506.5 mm (females) and 435.9 mm (males). The mean uterine fecundity was 3.3 (range = 1–8). The size at birth was between 190 and 220 mm WD . Year-round reproduction was indicated, due to the presence of mature males and gravid females throughout the year, neonates in multiple months and large variations in embryo size within months. Feeding intensity increased with body size. Fish accounted for 80.9% of the diet (Index of Relative Importance, IRI), followed by crustaceans (18.9%) and molluscs. The species was found to be a specialized feeder.

A critical appraisal of appendage disparity and homology in fishes

Article

Aug 2019
FISH FISH

Fishes are both extremely diverse and morphologically disparate. Part of this disparity can be observed in the numerous possible fin configurations that may differ in terms of the number of fins as well as fin shapes, sizes and relative positions on the body. Here, we thoroughly review the major patterns of disparity in fin configurations for each major group of fishes and discuss how median and paired fin homologies have been interpreted over time. When taking into account the entire span of fish diversity, including both extant and fossil taxa, the disparity in fin morphologies greatly complicates inferring homologies for individual fins. Given the phylogenetic scope of this review, structural and topological criteria appear to be the most useful indicators of fin identity. We further suggest that it may be advantageous to consider some of these fin homologies as nested within the larger framework of homologous fin‐forming morphogenetic fields. We also discuss scenarios of appendage evolution and suggest that modularity may have played a key role in appendage disparification. Fin modules re‐expressed within the boundaries of fin‐forming fields could explain how some fins may have evolved numerous times independently in separate lineages (e.g., adipose fin), or how new fins may have evolved over time (e.g., anterior and posterior dorsal fins, pectoral and pelvic fins). We favour an evolutionary scenario whereby median appendages appeared from a unique field of competence first positioned throughout the dorsal and ventral midlines, which was then redeployed laterally leading to paired appendages.

Smalltooth sawfish (Pristis pectinata Latham) in the Casamance River, Senegal – a historical perspective

Article

Jun 2018

1. A study of euryhaline elasmobranchs was conducted in the Casamance River, southern Senegal, between June 1974 and October 1975. 2. Data were collected from 159 sawfish, comprising 158 smalltooth sawfish (Pristis pectinata Latham, 1794) and one largetooth sawfish (Pristis pristis Linnaeus, 1758). 3. The mean total rostral tooth count for P. pectinata was 46 (range 41–53), significantly lower than the total tooth counts for the western Atlantic population. No sexual dimorphism in rostral tooth counts was apparent, in contrast to findings from the western Atlantic. 4. The total rostral length averaged 22.9% of the total length. 5. One hundred and forty‐four individuals were caught within the river system itself, all of them were juveniles. Fifteen adults, including the single largetooth sawfish documented during the study, were caught at the river mouth or at sea. 6. Six sawfish, caught between May and July, bore rostral sheaths, indicating that they had recently been born. 7. Although the Casamance and Gambia rivers are only 120 km apart, the findings from this study combined with published data collected from the Gambia River during the same period suggest the partitioning of juvenile habitats by the two sawfish species present in the region, to the level of different river systems. Both species are likely to have used the same coastal habitats as adults. 8. The Casamance River was clearly an important habitat for smalltooth sawfish some 40 years ago, but it is unknown whether the species persists there. Intensive artisanal fisheries for sharks and rays in the region poses a significant threat to any remaining sawfishes, and a challenge for elasmobranch fisheries management.

ESPÉCIES DE ELASMOBRÂNQUIOS DESEMBARCADAS NO PORTO DE ITAJAÍ, SUL DO BRASIL

Article

Full-text available

Dec 2010

Fishing activity in the Itajai harbor (SC) has concentrated a large fishing fleet, operating with many different methods of capture. This paper presents a checklist of the species of elasmobranchs landed in Itajai, and analyses the respective landing frequencies in the fishing methods. Elasmobranchs were observed in catches of purse seine, single trawl, double rig trawl, pair trawl, surface longline, bottom longline, surface gillnet, bottom gillnet and traps. In total, 85 species were found (54 sharks and 31 skates and rays) and of them, 22 shark species and 6 skates were very abundant in at least one fishing art.

Elasmobranchs from marine and freshwater environments in Colombia: A review

Chapter

Apr 2013

There is increasing interest in elasmobranch biology and diversity in the marine and continental environments of Colombia. The number of elasmobranch species are estimated to be about 124, but this number is likely to increase as more elasmobranchs are reported. Of these, eight species are freshwater stingrays. Populations of sharks and rays have been reducing in Colombia since the 1960s. Shark, ray and chimera fishery landings were about 157 T from 1958 to 1970 which reduced to about 76 T between 2001 and 2009 in the Colombian Atlantic Ocean. Shark, ray and chimera catches have diminished from 539 T from 1981 to 1990 to 353 T between 2001 and 2009 in the Colombian Pacific Ocean. However, catches from illegal fishing vessels of national and international origin are unreported so the actual rate of attrition is unknown. Broad taxonomic information has been gathered by the Colombian environmental and governmental institutions since 1957. Little research has been conducted on elasmobranch feeding ecology in the Colombian Atlantic and Pacific Oceans when compared to the total amount of elasmonbranch species reported for Colombia. Most studies in marine environments have focused on demersal elasmobranchs. Elasmobranch reproduction has been reported off the Atlantic and Pacific coasts and on the Magdalena River. Shark movements have been studied off the Colombian Pacific Ocean. Evidence exists from both scientists and fishermen that sharks venture into Colombian rivers. Colombia recently developed a National Action Plan for Conservation and Management of sharks, rays and chimeras. Elasmobranch fisheries in Colombia are not well documented. According to FAO (Food and Agriculture Organization) fisheries statistics, both Pacific and Atlantic oceans show a decrease in elasmobranch landings since the 1960s. More research is needed by Colombian scientists to better understand elasmobranch biology in the waters of northern South America.

The population dynamics of little skate Leucoraja erinacea, winter skate Leucoraja ocellata, and barndoor skate Dipturus laevis: Predicting exploitation limits using matrix analyses

Article

Jun 2002

Over the past thirty years catches of skates have increased in the western Atlantic as a result of targeted fisheries and as by-catch. Presently, sustainable harvest levels for skates in the western Atlantic are unknown. Available life history information was used to model three western Atlantic skate species, little skate Leucoraja erinacea, winter skate Leucoraja ocellata, and barndooor skate Dipturus laevis, to determine their population growth rate and susceptibility to population decline under exploitation. Population characteristics were estimated using age-based matrix analyses for little and winter skate and a stage-based matrix approach for barndoor skate. The intrinsic rate of population increase (r) for little, winter and barndoor skates were 0.21, 0.13 and 0.20, respectively. Fishing mortality resulting in equilibrium conditions, where the intrinsic rate of increase is zero, were 0.35 for little skate, 0.16 for winter skate and 0.20 for barndoor skate. Elasticity analyses indicated that juvenile survival contributed most to population growth in little skate and winter skate, and adult survival contributed the most in barndoor skate. Thus, conservation measures should focus on juvenile and adult stages of these species. In the absence of fishing mortality, elasticity of fecundity was low for all species, however; at high exploitation levels the contribution of fecundity to population growth rate increased. Stochastic analyses were performed by varying first year mortality (egg stage to the completion of one year of life), and model parameters for each species to generate estimates of the distributions of biological reference points. Our study supports the finding that long-lived, slower growing, late maturing species are highly vulnerable to exploitation. © 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights reserved.

Population Structure of Aetobatus narinari (Myliobatiformes) Caught by the Artisanal Fishery in Northeast Brazil

Article

Full-text available

Jun 2024
Diversity

In Brazil, the Whitespotted Eagle Ray Aetobatus narinari is considered data-deficient due to the scarcity of basic information on its biology, ecology, and vulnerability to capture. Despite this, the species is caught by artisanal fishing along most of the coast, especially in the northeast of Brazil. This study analyzed mitochondrial DNA data in specimens of A. narinari caught by artisanal fishing in the northeast coast of Brazil to understand their population structure. For this, 42 individuals were sequenced at three mitochondrial genes: cytochrome oxidase 1 (COI), cytochrome b (Cytb), and NADH dehydrogenase subunit 4 (ND4). Concatenated COI-Cytb-ND4 sequences yielded 14 haplotypes, with moderate haplotype diversity (h = 0.646), low nucleotide diversity (π = 0.00087), and low fixation index ΦST values, indicating no population structure. Our results suggest that there is only one population of A. narinari in the study area. Genetic studies can contribute to improving management plans in these areas, avoiding the overexploitation of this and other species.

The distribution of manta rays in the western North Atlantic Ocean off the eastern United States

Article

Full-text available

Apr 2022

In 2018, the giant manta ray was listed as threatened under the U.S. Endangered Species Act. We integrated decades of sightings and survey effort data from multiple sources in a comprehensive species distribution modeling (SDM) framework to evaluate the distribution of giant manta rays off the eastern United States, including the Gulf of Mexico. Manta rays were most commonly detected at productive nearshore and shelf-edge upwelling zones at surface thermal frontal boundaries within a temperature range of approximately 20–30 °C. SDMs predicted highest nearshore occurrence off northeastern Florida during April, with the distribution extending northward along the shelf-edge as temperatures warm, leading to higher occurrences north of Cape Hatteras, North Carolina from June to October, and then south of Savannah, Georgia from November to March as temperatures cool. In the Gulf of Mexico, the highest nearshore occurrence was predicted around the Mississippi River delta from April to June and again from October to November. SDM predictions will allow resource managers to more effectively protect manta rays from fisheries bycatch, boat strikes, oil and gas activities, contaminants and pollutants, and other threats.

Morphological abnormality in thornback ray Raja clavata in the Irish Sea

Article

Full-text available

Jun 2021

Leo J Clarke

A free-swimming thornback ray Raja clavata specimen demonstrating significant morphological abnormality is reported, captured by beam trawl in the Irish Sea off north Wales, UK. The anterior sections of both pectoral fins were separated from the head section for a length of approximately 140 mm extending from the rostrum tip to a point posterior of the spiracles, along with abnormal morphology of the gill slits. This phenomenon has been observed elsewhere but is the first documented example of this abnormality in the eastern Irish Sea, despite widespread targeting of the species across the region by commercial and recreational fishers. Possible causes and consequences of the observed abnormality are discussed.

Report of zonetail butterfly ray, Gymnura zonura (Bleeker, 1852) and mangrove stingray Urogymnus granulatus (Macleay 1883) (Chondrichthyes: Myliobatiformes) from Andaman waters, India

Article

Full-text available

Apr 2022

This paper reports the occurrence of two stingray species from Andaman waters, India; the zonetail butterfly ray Gymnura zonura (Bleeker, 1852) (695 mm DW) which represents a new distributional range, and the mangrove stingray Urogymnus granulatus (Macleay 1883) (395 mm DW) which represents a rare occurrence. These occurrences suggest hidden stingray diversity in this region. Morphological descriptions of both species, as well as a molecular barcode of G. zonura, were generated in the present study to clarify the taxonomic information. The current report assists in improving the understanding of the local diversity and distribution of batoids in Andaman waters, which is crucial for developing fishery management strategies.

Complete Mitochondrial DNA Genome of Nine Species of Sharks and Rays and Their Phylogenetic Placement among Modern Elasmobranchs

Article

Full-text available

Feb 2021

Chondrichthyes occupy a key position in the phylogeny of vertebrates. The complete sequence of the mitochondrial genome (mitogenome) of four species of sharks and five species of rays was obtained by whole genome sequencing (DNA-seq) in the Illumina HiSeq2500 platform. The arrangement and features of the genes in the assembled mitogenomes were identical to those found in vertebrates. Both Maximum Likelihood (ML) and Bayesian Inference (BI) analyses were used to reconstruct the phylogenetic relationships among 172 species (including 163 mitogenomes retrieved from GenBank) based on the concatenated dataset of 13 individual protein coding genes. Both ML and BI analyses did not support the “Hypnosqualea” hypothesis and confirmed the monophyly of sharks and rays. The broad notion in shark phylogeny, namely the division of sharks into Galeomorphii and Squalomorphii and the monophyly of the eight shark orders, was also supported. The phylogenetic placement of all nine species sequenced in this study produced high statistical support values. The present study expands our knowledge on the systematics, genetic differentiation, and conservation genetics of the species studied, and contributes to our understanding of the evolutionary history of Chondrichthyes.

Stingray spines embedded in the skull of a cobia

Article

Jul 2020

Steve Huskey

Improved Environmental DNA Reference Library Detects Overlooked Marine Fishes in New Jersey, United States

Article

Full-text available

May 2020

An accurate, comprehensive reference sequence library maximizes information gained from environmental DNA (eDNA) metabarcoding of marine fishes. Here, we used a regional checklist and early results from an ongoing eDNA time series to target mid-Atlantic U.S. coastal fishes lacking reference sequences. We obtained 60 specimens representing 31 species from NOAA trawl surveys and institutional collections, and analyzed 12S and COI barcode regions, the latter to confirm specimen identification. Combined with existing GenBank accessions, the enhanced 12S dataset covered most (74%) of 341 fishes on New Jersey State checklist including 95% of those categorized abundant or common. For eDNA time series, we collected water samples approximately twice monthly for 24 months at an ocean and a bay site in New Jersey. Metabarcoding was performed using separate 12S primer sets targeting bony and cartilaginous fishes. Bioinformatic analysis of Illumina MiSeq fastq files with the augmented library yielded exact matches for 90% of the 104 fish amplicon sequence variants generated from field samples. Newly obtained reference sequences revealed two southern U.S. species as relatively common warm season migrants: Gulf kingfish (Menticirrhus littoralis) and Brazilian cownose ray (Rhinoptera brasiliensis). A beach wrack specimen corroborated the local presence of Brazilian cownose ray. Our results highlight the value of strengthening reference libraries and demonstrate that eDNA can help detect range shifts including those of species overlooked by traditional surveys.

Dietary composition and trophic level of Hypanus marianae (Myliobatiformes: Dasyatidae), captured off Pernambuco coast, Brazil

Article

Full-text available

Nov 2019

Hypanus marianae, a stingray endemic to Brazil, inhabits coastal coral reef areas occurring in the landings of artisanal fisheries. The present study aimed to characterize the diet of this species captured off Pernambuco. We obtained 77 stomachs with contents: 52.27% female, 47.72% male. DW ranged from 15 to 37.80 cm mean of 26.53 ± 4.82 cm. Four higher taxonomic prey categories were identified: Arthropoda, Annelida, Chordata and Sipuncula. The most important item in the diet was Polychaeta (40.65% IRI), followed by Leptochela serratorbita (30.35% IRI), suborder Dendrobranchiata (10.18% IRI), order Isopoda (4.19% IRI), and Meiosquilla schmitti (3.56% IRI). H. marianae displays specialized predatory habit (BA = 0.06) primarily based on shrimps (42.36% IRI) and polychaetes (40.65% IRI). There was no significant difference in the diet by sex or in sexual development stages. However, neonates fed on decapods crustaceans (70.68%) and polychaetes (17.09%). For immatures, decapod crustaceans (69.5%) and polychaetes (25.86%) made up most of their diet. The adults feed mainly on polychaetes (62.79%) and crustacean decapods (30.47%), with a slight increase of fish (5.46%). The trophic level (TL) estimated was based on stomach content analysis was 3.66 and estimated on the analysis of stable isotopes being 3.29, which classified the species as a mesopredator.

CHAVES PARA A IDENTIFICAÇÃO DOS PEIXES DO OCEANO ATLÂNTICO ORIENTAL, MAR MEDITERRÂNEO E MAR NEGRO* KEYS TO THE FISHES OF THE EASTERN ATLANTIC OCEAN, MEDITERRANEAN SEA AND BLACK SEA* 1 – Myxini; Petromyzontida; Chondrichthyes

Article

Full-text available

Dec 2019

RESUMO. No presente trabalho os autores apresentam chaves de identificação para os peixes cartilagíneos que foram até à data referenciados para o Oceano Atlântico oriental, desde o norte da Noruega até à África do Sul, incluindo os mares Mediterrâneo e Negro e tendo como limite oeste uma linha arbitrária que acompanha grosseiramente a Crista Médio-Atlântica. Ao todo são consideradas 257 espécies, pertencentes a 49 famílias. Para cada espécie é apresentado um pequeno mapa de distribuição. PALAVRAS-CHAVE. Peixes, Myxini, Petromyzontida, Chondrichthyes, Oceano Atlântico oriental, Mediterrâneo, Mar Negro, chave de identificação, distribuição. ABSTRACT. Keys to the species of hagfishes, chimaeras, sharks and batoid fishes ocurring in the eastern Atlantic Ocean, from northern Norway until South Africa, including the Mediterranean and Black Seas are presented. The western limit adopted is an arbitrary line roughly following the Mid-Atlantic Ridge. A total of 257 species and 49 families are presente in the área. For each species a small distribution map is given. KEYWORDS. Pisces, Myxini, Petromyzontida, Chondrichthyes, eastern Atlantic Ocean, Mediterranean Sea, Black Sea, identification keys, distribution.

Notes on the reproductive biology of the Brazilian electric ray Narcine brasiliensis (Elasmobranchii: Narcinidae)

Article

Jan 2016
J FISH BIOL

First record and DNA Barcoding of Oman cownose ray, Rhinoptera jayakari Boulenger, 1895 from Andaman Sea, India

Article

Full-text available

Feb 2018

Strategically located to the southeast of the Bay of Bengal and northwest of the Malay Peninsula, the Andaman Sea houses rich and varied biological diversity both in its flora and fauna which is under explored. The present study reports the occurrence of Oman cownose ray, Rhinoptera jayakari Boulenger, 1895 as a new record from this region. A male specimen with a disc width of 494 mm was landed by a motorized longline boat in Junglighat fishing harbour. Port Blair, Andaman and Nicobar Islands fills the wide gap in the known distribution range of the species. A detailed morphological description of freshly collected specimen in comparison with those from the previous published reports elsewhere was carried out. Molecular marker based taxonomical annotation using Mitochondrial COI gene sequencing confirmed the identity of the specimen.

Ocorrência de vertebrados holocênicos marinhos, Elasmobranchii e Cetacea, no "Sambaqui de Camboinhas", Itaipu, Niterói, estado do Rio de Janeiro

Article

Full-text available

Jun 2017

O ''sambaqui de Camboinhas" foi descoberto no interior de uma "duna fóssil", dentro das cotas altimétricas de 7-8m acima do nível do mar, num trecho da Praia de ltaipu, Niterói, RJ. O referido sítio arqueológico foi pesquisado pelas arqueólogas Dras. Lina M. Kneip - Museu Nacional, UFRJ, Luciana Palestlini e Philomena Chiara - Museu Paulista, USP, no ano de 1979. As escavações arqueológicas favoreceram a descoberta de representantes da fauna marinha ligados ao meio ambiente, tais como Elasmobranchii (raias e tubaróes), Teleostei (piraúna, xaréu e bagre) e Cetacea (golfinho e baleia), juntamente com os invertebrados Crustacea e Mollusca Acompanhamos parte das atividades de campo e verificamos, cJentro das superfícies expostas das escavações, alguns restos esqueletais, incompletos, porém ordenados. Apresentamos aquí, os resultados das pesquisas elaboradas sobre os restos de vertebrados marinhos.

Adult and offspring size in the ocean: A database of size metrics and conversion factors

Article

Feb 2016

The purpose of this dataset was to compile adult and offspring size estimates for marine organisms. Adult and offspring size estimates of 408 species were compiled from the literature covering >17 orders of magnitude in body mass and including Cephalopoda (ink fish), Cnidaria (“jelly” fish), Crustaceans, Ctenophora (comb jellies), Elasmobranchii (cartilaginous fish), Mammalia (mammals), Sagittoidea (arrow worms) and Teleost (i.e. Actinopterygii, bony fish). Individual size estimates were converted to standardized size estimates (carbon weight, g) to allow for among-group comparisons. This required a number of size estimates to be converted and a compilation of conversion factors obtained from the literature are also presented. Mean species-specific adult and offspring size estimates resulting from these databases are given in Neuheimer et al. (in press, Ecology, Supplement 1). This article is protected by copyright. All rights reserved.

Sympatric and syntopic occurrence of cownose rays: Neonatal strategies for survival?

Article

Full-text available

Mar 2017
J APPL ICHTHYOL

Segmentations of the cartilaginous skeletons of chondrichthyan fishes by the use of state-of-the-art computed tomography

Article

Full-text available

Dec 2016

Aim: To apply dual-source multidetector computed tomography (DSCT) scanning technology in conjunction with computationally assisted segmentation in order to explore and document skeletal variation that has occurred over the course of evolution. Methods: We examined 4 divergent species of elasmobranchs with high-resolution 3(rd) generation DSCT. The formalin prepared species examined were: Aptychotrema vincentiana, Mitsukurina owstoni, Negaprion brevirostris and Dactylobatus armatus. Results: All three structures of the hyoid arch (hyomandibular, ceratohyal, and basihyal) were clearly visible whereas in the two batoids, the hyomandibular was the prominent feature, the ceratohyal was not visible and the basihyal was more reduced and closer to the gill arches. The general shape of the puboischiadic bar, or pelvic girdle, illustrated a closer relationship between the two sharks and the two batoids than between the two groups. Conclusion: In exquisite detail, DSCT imaging revealed important morphological variations in various common structures in the four elasmobranch specimens studied, providing insights into their evolutionary diversification.

Re-description of the longtail butterfly ray, Gymnura poecilura (Shaw, 1804) (Gymnuridae: Myliobatiformes) from Bay of Bengal with a neotype designation

Article

Aug 2016

The longtail butterfly ray, Gymnura poecilura, was originally described as Raja poecilura by Shaw 1804 without any type material, based on Russell’s (1803) illustration of “Tenkee kunsul” from Vizagapatam (present day Visakhapatnam), India. Because of the absence of detailed taxonomic accounts for G. poecilura, characters mentioned for its identification are often misleading and unreliable, leading to frequent misidentification of the species with congeners in the region. In the absence of type specimens or detailed taxonomic work on the genus Gymnura from the Indian Ocean region, species G. poecilura is considered to be undefined. In an effort to clear up the taxonomic vagueness of the species, this article re-describes G. poecilura from fresh materials, designates a neotype from Visakhapatnam, India (western Bay of Bengal) and also reports the presence of a distinct Gymnura species from the northern Arabian Sea with genetic support. Reports of two butterfly rays, G. japonica and G. micrura, from Indian waters are clarified as misidentifications and so must be excluded from the Indian elasmobranch faunal list.

Adult and offspring size in the ocean: a database of size metrics and conversion factors

Article

Full-text available

Apr 2016
ECOLOGY

The purpose of this dataset was to compile adult and offspring size estimates for marine organisms. Adult and offspring size estimates of 408 species were compiled from the literature covering >17 orders of magnitude in body mass and including Cephalopoda (ink fish), Cnidaria (“jelly” fish), Crustaceans, Ctenophora (comb jellies), Elasmobranchii (cartilaginous fish), Mammalia (mammals), Sagittoidea (arrow worms) and Teleost (i.e., Actinopterygii, bony fish). Individual size estimates were converted to standardized size estimates (carbon weight, g) to allow for among-group comparisons. This required a number of size estimates to be converted and a compilation of conversion factors obtained from the literature are also presented.

Terminologie en determinatie van haaien- en roggentanden.

Article

Full-text available

Dec 2013

Taco Bor

Terminology and identification of shark and batoid teeth [in Dutch].

Complete mitochondrial DNA genome of bonnethead shark, Sphyrna tiburo, and phylogenetic relationships among main superorders of modern elasmobranchs

Article

Full-text available

Feb 2016

Elasmobranchs are one of the most diverse groups in the marine realm represented by 18 orders, 55 families and about 1200 species reported, but also one of the most vulnerable to exploitation and to climate change. Phylogenetic relationships among main orders have been controversial since the emergence of the Hypnosqualean hypothesis by Shirai (1992) that considered batoids as a sister group of sharks. The use of the complete mitochondrial DNA (mtDNA) may shed light to further validate this hypothesis by increasing the number of informative characters. We report the mtDNA genome of the bonnethead shark Sphyrna tiburo, and compare it with mitogenomes of other 48 species to assess phylogenetic relationships. The mtDNA genome of S. tiburo, is quite similar in size to that of congeneric species but also similar to the reported mtDNA genome of other Carcharhinidae species. Like most vertebrate mitochondrial genomes, it contained 13 protein coding genes, two rRNA genes and 22 tRNA genes and the control region of 1086 bp (D-loop). The Bayesian analysis of the 49 mitogenomes supported the view of sharks and batoids are separate groups.

Occurrence and use of an estuarine habitat by giant manta ray Manta birostris

Article

Full-text available

Apr 2015

Based on the knowledge of local artisanal fishermen and on direct observations, this study presents evidence that the giant manta ray Manta birostris uses the Paranaguá estuarine complex in south Brazil, south-western Atlantic Ocean, in a predictable seasonal pattern. Behavioural observations suggest that the estuary can act as a nursery ground for M. birostris during the summer. © 2015 The Fisheries Society of the British Isles.

Global list of cold-water corals (order Scleractinia; sub-order Filifera; subclass Octocorallia, order Antipatharia) from waters deeper than 200 m, vulnerable species, and draft recommendations for the production of identification guides

Chapter

Full-text available

Jan 2011

Marcelo Visentini Kitahara

molecular plylo Mobulidae

Data

Full-text available

Dec 2014

A dated molecular phylogeny of manta and devil rays (Mobulidae) based on mitogenome and nuclear sequences

Article

Nov 2014
MOL PHYLOGENET EVOL

Inshore occurrences of the pelagic stingray, Pteroplatytrygon violacea, (Bonaparte, 1832) (Elasmobranchii: Dasyatidae), in São Paulo coast, southeastern Brazil

Article

Full-text available

Nov 2012

Inshore occurrences of the pelagic stingray, Pteroplatytrygon violacea, (Bonaparte, 1832) (Elasmobranchii: Dasyatidae), Abstract. Fifteen specimens of the pelagic stingray, Pteroplatytrygon violacea were caught in depth between 9 and 50 m off São Paulo State coast, among them the largest recorded size in nature with 90 cm disk width. Resumo. Ocorrências costeiras da raia-pelágica, Pteroplatytrygon violacea, (Bonaparte, 1832) (Elasmobranchii: Dasyatidae), na costa do Estado de São Paulo, Sudeste do Brasil. Quinze espécimes da raia-pelágica, Pteroplatytrygon violacea foram capturados entre 9 e 50 metros de profundidade na costa de São Paulo, entre eles um recorde de tamanho na natureza com 90 cm de largura de disco.

in São Paulo State, southeastern Brazil

Article

Full-text available

Jan 2011

Inshore occurrences of the pelagic stingray, Pteroplatytrygon violacea, (Bonaparte, 1832) (Elasmobranchii: Dasyatidae), Abstract. Fifteen specimens of the pelagic stingray, Pteroplatytrygon violacea were caught in depth between 9 and 50 m off São Paulo State coast, among them the largest recorded size in nature with 90 cm disk width. Resumo. Ocorrências costeiras da raia-pelágica, Pteroplatytrygon violacea, (Bonaparte, 1832) (Elasmobranchii: Dasyatidae), na costa do Estado de São Paulo, Sudeste do Brasil. Quinze espécimes da raia-pelágica, Pteroplatytrygon violacea foram capturados entre 9 e 50 metros de profundidade na costa de São Paulo, entre eles um recorde de tamanho na natureza com 90 cm de largura de disco.

Sawfishes, Guitarfishes, Skates and Rays: Part 2

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