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Fishes of the Western North Atlantic. Part Two. Sawfishes, Guitarfishes, Skates and Rays [and] Chimaeroids
... Sawfish species (family Pristidae) and sawshark species (family Pristiophoridae) have among the most extreme examples of elongated rostra. Rostra of sawfish compose up to 25% of the total body length, and both sawfishes and sawsharks have tooth-like scales referred to as rostral teeth along the lateral margins of their rostra (Bigelow and Schroeder, 1953;Miller, 1974Miller, , 1995Last and Stevens, 2009). These groups are thought to have evolved their rostra independently (Slaughter and Springer, 1968), indicating that broad or shared advantages of rostrum elongation span the deepwater habitats of sawsharks and the shallowwater habitats of sawfishes (Last and Stevens, 2009;Poulakis et al., 2011). ...
... The gross morphology and microscopic anatomy of these sheaths has not been investigated, and for sawfishes, the coverings have been described as "transparent cartilaginous tissue" (Southwell, 1910), a "membrane" (Hussakof, 1912;Setna and Sarangdhar, 1948), and "gelatinous" (Abel and Grubbs, 2020). Although they apparently refer to the sheath as both "skin" and an unspecified "narrow band," Bigelow and Schroeder (1953) indicated that the rostral teeth of sawfish embryos are "entirely enclosed in the skin until birth, while a narrow band along each margin of the saw is naked, both below and above." Contrary to the description by Bigelow and Schroeder (1953) of rostral teeth as soft until birth, rostral teeth form and calcify early in gestation and the sheath forms around the entire tooth-bearing portion of the rostrum (Miller, 1995). ...
... Although they apparently refer to the sheath as both "skin" and an unspecified "narrow band," Bigelow and Schroeder (1953) indicated that the rostral teeth of sawfish embryos are "entirely enclosed in the skin until birth, while a narrow band along each margin of the saw is naked, both below and above." Contrary to the description by Bigelow and Schroeder (1953) of rostral teeth as soft until birth, rostral teeth form and calcify early in gestation and the sheath forms around the entire tooth-bearing portion of the rostrum (Miller, 1995). The sheath prevents the rostral teeth of embryos from damaging 1) siblings and the uterus during gestation and 2) the female's cloaca during parturition (Setna and Sarangdhar, 1948). ...
... A família Dasyatidae inclui raias marinhas e estuarinas que apresentam ferrão em uma cauda longa que se assemelha a um chicote, sendo conheci das em inglês como "whiptail stingrays" (Bigelow & Schroeder, 1953;Compagno, 1999a,b). ...
... O gênero Himantura (Muller & Henle, 1837) pertence à família Dasyatidae e apresenta espécies com uma distribuição predominante tropical do Indo-Pacifico oeste, sendo encontradas poucas espé cies nas porções tropicais do Atlântico oeste e Paci fico leste (Compagno, 1999b). Os registros de ocor rência apontam a existência de duas espécies anfiamericanas: Himantura schmardae (Werner, 1904) na costa Atlântica (sul da América do Norte, América Central e extremo norte da América do Sul) e Himantura pacifica (Beebe & Tee-Van, 1941) na costa Pacifica (sul da América do Norte e América Central) (Beebe & TeeVan, 1941;Lopez & Bussing, 1982;Bigelow & Schroeder, 1953;CastroAguirre, 1978;Cervigón et al., 1992). A distribuição de H. schmardae era conheci da como sendo desde o Suriname até a região de Ta basco, no México, passando por Cuba, Jamaica e Trindade (Bigelow & Schroeder, 1953;CastroAguirre, 1978;Cervigón et al., 1992). ...
... Os registros de ocor rência apontam a existência de duas espécies anfiamericanas: Himantura schmardae (Werner, 1904) na costa Atlântica (sul da América do Norte, América Central e extremo norte da América do Sul) e Himantura pacifica (Beebe & Tee-Van, 1941) na costa Pacifica (sul da América do Norte e América Central) (Beebe & TeeVan, 1941;Lopez & Bussing, 1982;Bigelow & Schroeder, 1953;CastroAguirre, 1978;Cervigón et al., 1992). A distribuição de H. schmardae era conheci da como sendo desde o Suriname até a região de Ta basco, no México, passando por Cuba, Jamaica e Trindade (Bigelow & Schroeder, 1953;CastroAguirre, 1978;Cervigón et al., 1992). ...
A distribuição das espécies do gênero Himanturaé conhecida para a região do Indo-Pacífico e América Central (Oceanos Atlântico e Pacífico) em águas doces e estuarinas. Este é o primeiro registro do gênero e da espécie Himanturaschmardae na costa do Brasil. Quatro exemplares desta espécie foram capturados em diferentes pescarias com rede-de- arrasto de fundo nos meses de setembro de 1996 e abril de 1997 na foz do Rio Amazonas. Um exemplar macho imaturocom comprimento total de 128 cm e largura de disco de 54 cm encontra-se depositado na Coleção Ictiológica do Museu Paraense Emílio Goeldi (número de registro MPEG 3547). A espécieH. schmardae é conhecida pelo nome vulgar eminglês de chupare stingray e regionalmente recebe nome de arraia-redonda. O registro de ocorrência desta espécie na foz do Rio Amazonas pode ser significativo para auxiliar a esclarecer uma das hipóteses sobre a origem das raias de água doce(Potamotrygonidae).
... All specimens from the northern coast of South America (Colombia to Brazil) were found to be very variable in most morphological characteristics but to be identical in skeletal structure. Based on overlapping proportional measurements and a lack of distinguishing characters (both internal and external), D. altenai Boeseman 1963 is synonymized with D. pictus Palmer 1950, and the placement of D. guamachensis ~lartin 1957 in synonymy with D. pictus by Bigelow and Schroeder (1962) is verified. Three subspecies are recognized within D. pictus: D. pictus l}ictus Palmer, D. pictus guamachensis Martin, and D. pictus colombiensis new subspecies. ...
... His work suggests that Torpediniformes is a monophyletic group derived from the guitarfishes (Rhinobatiformes) and distinguished by the following derived characters: huge pectoral electric organs; no supraorbital crests on the neurocranium, anteriorly directed, fanor antler-shaped antorbital cartilages, extending to but not articulating with propterygia of pectoral fins; and unique pectoral girdles, with a strut-supported posterior tube-like extension holding a rhinobatoid-like articular surface for the pectoral basals (Compagno 1977). Phylogenetically, the Torpediniformes are something of an enigma: while they exhibit some plesiomorphic character states and are most often allied with primitive batoid groups (Gegenbaur 1865;Daniel 1934;Bigelow and Schroeder 1953;Compagno 1977), they possess several highly derived character states that are not shared with any other orders of Batoidea (Heemstra and Smith 1980). Torpediniformes are also the last batoid group to appear in the fossil record (Romer 1966), and recent work on chromosome number and genome size suggests a more advanced phylogenetic position for this group (Donahue 1974;Stingo 1979). ...
... Diplobatis Bigelow and Schroeder 1948 has a subcircular disc with a moderately convex anterior edge, normal functional eyes, nostrils subdivided into two apertures, and a narrow lateral fold on the tail. Representatives are found in the eastern Pacific Ocean from the Gulf of California to Colombia and in the western Atlantic Ocean from Colombia to the mouth of the Amazon River (Bigelow and Schroeder 1953). Considerable confusion exists as to the number of distinct species within Diplobatis. ...
We examined the morphological characters and internal anatomical features of the electric ray genus Diplobatis (Torpediniformes, Narcinidae) in order to determine the taxonomic status of the various forms. All specimens from the northern coast of South America (Colombia to Brazil) were found to be very variable in most morphological characteristics but to be identical in skeletal structure. Based on overlapping proportional measurements and a lack of distinguishing characters (both internal and external), D. altenai Boeseman 1963 is synonymized with D. pictus Palmer 1950, and the placement of D. guamachensis Martin 1957 in synonymy with D. pictus by Bigelow and Schroeder (1962) is verified. Three subspecies are recognized within D. pictus: D. pictus pictus Palmer, D. pictus guamachensis Martin, and D. pictus colombiensis new subspecies. D. ommata (Jordan and Gilbert 1890), from the Pacific coasts of Mexico and Central America, is found to be identical to D. pictus in skeletal anatomy and similar to its congener in most proportional measurements. D. ommata is distinguished from D. pictus by its dorsal color pattern and differing clasper morphology. The genus and species of Diplobatis are redefined, and the three subspecies are described. Finally, the four genera of Narcinidae (Benthobatis, Diplobatis, Discopyge, and Narcine) are compared and found to be very conservative anatomically. A phylogenetic analysis based on synapomorphic character states shows Discopyge and Narcine to be the sister group to the other narcinids.
... scient, tech. Océanogr On trouve ce Sélacien sur les deux rives de l'Atlantique ; le long des côtes occidentales, Bigelow et Schroeder (1953) notent, en effet, sa capturedepuis la nouvelle Angletene jusqu'au brésil, au large de Rio-de-Janeiro et de l'embouchure du rio Grande. Sur la bordure orientale, G. altavela est mentionnée dans le golfe de Gascogne (région d Arcachon) par Cazaux et Labourg (1971), le long du littoral portugais) Albuquerque, 1954Albuquerque, -1956, des côtes marocaines (Collignon et Aloncle, 1972), mauritaniennes (Maurin et Bonnet, 1970), sénégalaises (Cadenat, 1951 ) et guinéennes (Blache, Cadenat et Stauch, 1970). ...
... G. altavela est bien connue sur le plan systématique et a fait l'objet de descriptions approfondies au moins en ce qui concerne la morphologie générale, certains caractères spécifiques comme les dents, ... (Garman, 1913 ;Lozano Rey, 1928 ;Bigelow et Schroeder, 1953 ;Albuquerque, 1954Albuquerque, -1956Tortonese, 1956 ;Bini, 1967). En revanche, il n'existe que peu de travaux relatifs à l'anato mie du neurocrâne, de la ceinture pelvienne (illustration donnée par Garman, 1913) et des ptérygopodes (brève description de la morphologie externe donnée par Leigh-Sharpe, 1926). ...
... Les dents sont disposées en rangées le plus souvent en quinconce, de 7 à 11 rangées. Le nombre de rangées de dents semble varier d 'après les auteurs : 98-138/78-1 K) (Bigelow et Schroeder, 1953), 50-100 (Fowler, 1936 ;Albuquer que, 1954), 150/110-120 (Bini, 1967. Comme Bigelow et Schroeder, nous avons constaté que le nombre de rangées de dents augmente avec la taille des individus et nous avons trouvé comme formule dentaire 88-120/76-112 en consi dérant les chiffres extrêmes. ...
... In the eastern Atlantic, P. pectinata inhabited coastal waters from Mauritania to Angola, but no viable populations are thought to remain (Carlson, Wiley & Smith, 2013). In the western Atlantic, historical literature indicates that P. pectinata occurred from Uruguay to the US and throughout the Caribbean (Bigelow & Schroeder, 1953). The only known remaining viable populations are restricted to the south-eastern US, and The Bahamas (Carlson, Wiley & Smith, 2013). ...
... Within the US, P. pectinata once occurred in coastal waters from Texas to North Carolina, but by the 1980s were restricted to south and southwest Florida (SWFL), specifically Charlotte Harbor to the Florida Keys, hereafter referred to as the 'core range' (Bigelow & Schroeder, 1953;NMFS, 2009; Figure 1). Historical surveys noted Galveston Bay, the mouth of the Mississippi River, Lake Pontchartrain, Pascagoula Bay, Mobile Bay, Tampa Bay, and the Indian River Lagoon (IRL) as areas where specimens were collected, or large numbers of individuals were observed (Goode, 1884;Jordan & Swain, 1884;Henshall, 1891;Henshall, 1895;Evermann & Bean, 1898). ...
... Some works even mention gravid females or small juveniles in Galveston Bay, Biloxi Bay, Charlotte Harbor, Florida Bay, and the IRL (e.g. Evermann & Bean, 1898;Bigelow & Schroeder, 1953). Although individuals have also been reported on the US east coast north of Florida, the presence of a consistent, yearround historical population in these waters is unlikely based on the lack of mangrove habitat and low average winter water temperatures (≤12 C; Poulakis et al., 2011;Brame et al., 2019). ...
• Formerly common in tropical and subtropical waters of the Atlantic Ocean, the Critically Endangered smalltooth sawfish, Pristis pectinata, underwent severe declines over the past century, restricting population(s) to south and south-west Florida in the US, and Bahamian waters.
• Anecdotal evidence (e.g. encounter reports from the public) suggests that P. pectinata have recently been observed in historically occupied US waters; however, no directed surveys have been conducted to verify their extent of occupancy.
• Here, environmental DNA (eDNA) surveys were used to investigate the occurrence of P. pectinata in three formerly occupied estuaries in US waters. Water samples were collected in the summer from the Indian River Lagoon and Tampa Bay, Florida, in 2018 and 2019, and from Mississippi Sound, Mississippi, in 2018, and screened for target DNA using a highly sensitive Droplet Digital™ polymerase chain reaction assay.
• Target DNA was detected at four sites in the Indian River Lagoon in 2018 and at one site in 2019 (average concentration: 0.086 copies μl⁻¹; SE = 0.004), but was not detected in either year in Tampa Bay. Target DNA was also detected at three sites near Deer Island in Mississippi Sound in 2018 (average concentration: 0.090 copies μl⁻¹; SE = 0.005). These surveys provide additional lines of evidence that P. pectinata is re-occurring within two historically occupied estuaries in US waters.
• More comprehensive eDNA surveys in historically occupied regions, combined with clearly defined post-survey management actions, can direct additional research and outreach initiatives in emerging priority areas, fostering recovery of this Critically Endangered species.
... To test these hypotheses, we examined two ecologically similar congeners, the Atlantic stingray, H. sabinus (Lesueur 1824) and the bluntnose stingray, H. say (Lesueur 1817). Both stingray species occur in shallow, inshore, coastal and estuarine habitats (Bigelow and Schroeder 1953;Thorson 1983;Snelson et al. 1988) and are sympatric in the Western Atlantic and Gulf of Mexico (Bigelow and Schroeder 1953;Robins and Ray 1986;Snelson et al. 1989). Hypanus say can grow to a larger size (52-73 cm disc width, (Snelson et al. 1989)) than H. sabinus (27-45 cm disc width, (Last et al. 2016)), but they share a similar diet of gastropods, worms, and bivalves (Bigelow and Schroeder 1953;Michael 1993;Dulvy and Reynolds 1997;Smith 1997). ...
... To test these hypotheses, we examined two ecologically similar congeners, the Atlantic stingray, H. sabinus (Lesueur 1824) and the bluntnose stingray, H. say (Lesueur 1817). Both stingray species occur in shallow, inshore, coastal and estuarine habitats (Bigelow and Schroeder 1953;Thorson 1983;Snelson et al. 1988) and are sympatric in the Western Atlantic and Gulf of Mexico (Bigelow and Schroeder 1953;Robins and Ray 1986;Snelson et al. 1989). Hypanus say can grow to a larger size (52-73 cm disc width, (Snelson et al. 1989)) than H. sabinus (27-45 cm disc width, (Last et al. 2016)), but they share a similar diet of gastropods, worms, and bivalves (Bigelow and Schroeder 1953;Michael 1993;Dulvy and Reynolds 1997;Smith 1997). ...
... Both stingray species occur in shallow, inshore, coastal and estuarine habitats (Bigelow and Schroeder 1953;Thorson 1983;Snelson et al. 1988) and are sympatric in the Western Atlantic and Gulf of Mexico (Bigelow and Schroeder 1953;Robins and Ray 1986;Snelson et al. 1989). Hypanus say can grow to a larger size (52-73 cm disc width, (Snelson et al. 1989)) than H. sabinus (27-45 cm disc width, (Last et al. 2016)), but they share a similar diet of gastropods, worms, and bivalves (Bigelow and Schroeder 1953;Michael 1993;Dulvy and Reynolds 1997;Smith 1997). Their overlapping ranges, similar ecologies, and congeneric relationship would lead us to hypothesize that their spine morphology and puncture/withdrawal forces should be generally similar. ...
A diagnostic characteristic of stingrays in the Family Dasyatidae is the presence of a defensive, partially-serrated spine located on the tail. We assessed the contribution of caudal spine morphology on puncture and withdrawal performance from two congeneric, co-occurring stingrays, the Atlantic stingray, Hypanus sabinus, and the bluntnose stingray, Hypanus say. Spines exhibited a high degree of morphological variability. Stingray spines were serrated along 50.8% (H. sabinus) or 62.3% (H. say) of their length. Hypanus say had a greater number of serrations along each side of the spine (30.4) compared to H. sabinus (20.7) but pitch did not differ between species. We quantified spine puncture and withdrawal forces using porcine skin as a model for human skin. Puncture and withdrawal forces did not differ significantly between species, or within H. say, but withdrawal force was greater than puncture force for H. sabinus. We incorporated micro-CT scanning to quantify tissue mineral density and found that for both species, the shaft of the spine was more heavily mineralized than the base, and midway (50%) along the length of the spine was more heavily mineralized than the tip. The mineralization variability along the spine shaft may create a stiff structure that can fracture once embedded within the target tissue and act as an effective predator deterrent.
... Both species are benthopelagic and indigenous to tropical and temperate shallow waters along continental shelves (Last et al., 2016). Historically, tooth series counts were used to distinguish between these two species, despite ambiguity arising from overlap in series counts (Bigelow & Schroeder, 1953). Recent research documented changes in tooth morphology with age, making this characteristic unreliable (Jones et al., 2017). ...
... The range of R. bonasus extends from New England in the United States to northern Argentina (Last et al., 2016). Historically, R. brasiliensis was considered endemic to Brazil, restricted to the waters of southern Brazil (Barker, 2006;Bigelow & Schroeder, 1953). Recent literature extended the range of R. brasiliensis to include Central America (McEachran & Carvalho, 2002), the southern Gulf of Mexico (Palacios-Barreto et al., 2017), and the northern Gulf of Mexico (Jones et al., 2017), using a combination of morphological and molecular methods in species identifications. ...
... data), one of unknown size from North Carolina with an unknown capture date in 2008 (Naylor et al., 2012), and one from a deceased specimen of unknown size found on a beach in New Jersey in summer (August) 2017 (Stoeckle et al., 2020). There is one additional historic record from North Carolina, but since this identification was based on tooth series counts alone (Bigelow & Schroeder, 1953), it is not considered reliable. Despite these records, the Atlantic was not considered part of the accepted range of R. brasiliensis in subsequent accounts (e.g., ...
We report 24 new records of the Brazilian cownose ray Rhinoptera brasiliensis outside its accepted geographic range. Sequencing of a 442‐base pair portion of the mitochondrial NADH dehydrogenase subunit 2 gene for 282 Rhinoptera samples revealed eight records off the east coast of the USA and 16 from the eastern Gulf of Mexico. Both sexes of all life stages were documented in all seasons over multiple years in the Indian River and Lake Worth lagoons, Florida, indicating that their range extends further in the western North Atlantic than previously described.
... In the guitarfish Z. brevirostris and all skates examined, this nasal flap is expanded laterally and completely covers the excurrent nasal aperture and posterior nasal flap (23, 1). Despite of what was described by previous authors (Bigelow & Schroeder, 1953;Hubbs & Ishiyama, 1968;Leible, 1988), anterior nasal flaps are not fused together to form a nasal curtain in rajiforms since both flaps display free margins that can be moved independently from each other ( 28. Pelvic fin: (0) not subdivided, (1) divided in two distinct lobes [ch. ...
... In Rioraja and Atlantoraja, the pectoral propterygium does not reach the rostral appendix, and the same condition is also observed in Amblyraja radiata, D. cf. leptocauda, L. garmani, M. senta, Raja miraletus and Rajella sadowskii (62, 0; see also Bigelow & Schroeder, 1953;Carvalho et al., 2005;Ishiyama, 1958;Jeong & Nakabo, 2008). The propterygium of pectoral girdle extends anteriorly to the rostral node in B. nigriventralis, C. rugosa, G. atlantica, N. azurea, P. extenta, S. acuta and S. bonapartii (62, 1). ...
The tribe Riorajini is composed of four species, Rioraja agassizii , Atlantoraja castelnaui , A. cyclophora and A. platana , which are endemic to the inshore waters of the Southwestern Atlantic Ocean. Previous studies have hypothesized the monophyly of this group but interrelationships within its members remain not fully understood. In this study, we analysed quantitative as well as qualitative morphological characters related to external morphology, squamation, neurocranium, visceral arches, pectoral and pelvic girdles and claspers, totalizing 82 characters, representing a greater number than previously used in studies focused on rajiform systematics. 24 terminal taxa were included, and two different analyses were carried out testing Narcine brasiliensis and Pseudobatos horkelii as roots of the cladogram. The monophyly of Riorajini is supported by five quantitative and three discrete characters, including a caudal length smaller than disc length, sensory pores and mucous canals darkly pigmented on ventral surface of disc, and preorbital flange present. Clasper morphology was phylogenetically informative since it contributes to diagnose Rioraja in which an accessory terminal 2 cartilage is absent and to support a sister relationship between A. cyclophora + A. platana . Squamation, teeth and neurocranial morphology need to be thoroughly investigated in order to revise their terminology, propose and test hypotheses of homology and improve our knowledge on morphological variation regarding ontogeny and sexual dimorphism.
... Ces deux espèces ont souvent été confondues. Si Bigelow et Schroeder (1953) d'une part, Blache, Cadenat et Staucii (1970) d'autre part, semblent considérer T. (T.) mackayana comme dis¬ tincte de T. (T.) nobiliana, il apparaît, comme l'ont souligné Quiîro et coll. (1976), que les illustrations publiées sous le nom de T. noèiZianaparCADENAT (1950( ) et parPoLL(1951 corres¬ pondent à la figure qui accompagne la description de T. mackayana par Metzelaar (1919). ...
... Notons que chez ces dernières la cuspide est très légèrement incurvée vers l'extérieur ( fig. 6). Le nombre de dents semble augmenter progressivement avec la taille, ce qui explique les chiffres souvent différents donnés par les auteurs : 36/34 (Garman, 1913), 38/38 chez les jeunes et 48/46 à 66/61 chez les adidtes (Bigelow et Schroeder, 1953), 66/66 (Tortonese, 1956), 38-66/38-61 (Bini, 1967). Nous avons fait des observations identiques pour les spécimens des côtes tunisiennes mais le phénomène est encore plus marqué après la maturité sexuelle comme l'indiquent la figure 7 et le tableau I qui montrent la relation existant entre la taille et le nombre de rangées de dents de la mâchoire supérieure. ...
... Fowler (1941) considered this spices to be synonym of T. marmorata. Ahmad and Niazi (1975), Bigelow and Schroeder (1953), Belgvad (1944) and Mould (1997) consider this to be synonym of Torpedo panthera. Compagno (1999), Eschmeyer (2021), Prashad (1920) and Setna and Saranghdhar (1949) consider this to be a valid species. ...
... This darkly mottled or spotted colour pattern clearly distinguishes this species from T. adenensis as well as from T. panthera. Bigelow and Schroeder (1953) placed T. zugmayeri in the synonymy of T. panthera, but without elaborating, and overlooking the clear distinctions in coloration present in the original description. According to , it could be either a junior synonym of T. fuscomaculata, because of the described similarities in dorsal colour, a junior synonym of T. sinuspersici, or a valid species. ...
Electric rays (Order Torpedoniformes) represented by 13 species belonging to 4 genera and 3 families are reported from Pakistan. Genus Narcine is reported by 6 species, Torpedo by 5 species and Benthobatis and Narke by 1 species each. Torpedo zugmayeri was described from Gwadar Pakistan by Englehardt (1912) which was generally included in the synonym of T. panthera, T. fuscomaculata or T. sinuspersici, however, during the present study a number of specimens collected from Pakistan were examined and it was concluded that it is valid species. Based on the available specimens, two species Torpedo adenensis and Narcine oculifera are reported for the first time from Pakistan coast. Although no specimen of Narcine atzi from Pakistan was examined but considering its wide distribution in the Arabian Sea and Bay of Bengal, its presence in Pakistan cannot be overruled. There seems to be little knowledge available about abundance and distribution of various species of electric ray occurring in the area. Evaluation of International Union for Conservation of Nature (IUCN) Red listing is available for 11 out of 13 species occurring in Pakistan. Two species Torpedo zugmayeri and Narcine brunnea were not evaluated mainly because, these were included in synonymy of other species whereas one species Benthobatis moresbyi was rated as least concern (LC). Torpedo adenensis was rated as Endangered (EN). Remaining species are considered as data deficient (DD). Considering limited available information, it was stressed to study biology, ecological role in the benthic ecosystem and stock abundance of electric rays from Pakistan.
... There is evidence to suggest that their growth follows Bergmann's rule (Mayr 1956;Lindsey 1966). The reported maximum total length of Clearnose Skate from Massachusetts, North Carolina, and South Carolina typically ranges from 700 to 745 mm, 570 to 687 mm, and 568 to 640 mm, respectively (Bigelow and Schroeder 1953;Schwartz 1996). The length at maturity is estimated to be between 560 and 650 mm from New England skates (Sosebee 2004) and between 535 and 568 mm from South Carolina and northern Florida skates. ...
... Some individuals visit Cape Fear River, North Carolina, between February and November, with an occasional absence in June and July when temperatures are highest (Schwartz 2000). It has been noted that Clearnose Skate between South Carolina and eastern Florida remain in coastal waters year-round (Bigelow and Schroeder 1953). ...
Skates (family Rajidae) are benthic elasmobranchs that are highly vulnerable to incidental fishery bycatch, are discarded at sea, and are poorly accounted for in catch records. Many aspects of skate life history, such as population structure, are not well understood. Without this knowledge, indiscriminate removal may have deleterious effects on scientific, conservation, and management efforts. The Clearnose Skate Rostroraja eglanteria is seasonally migratory and widely distributed in the coastal waters of the eastern United States and in the northeastern Gulf of Mexico. This study used molecular techniques to assess the population structure of Clearnose Skate for use as a biological reference point for further research and management. Specimens were collected from 2014 to 2019 by fisheries‐independent surveys. High‐throughput genotyping‐by‐sequencing was used to identify single nucleotide polymorphisms, resulting in two data sets: one consisting of 8,914 loci (outlier and neutral) and the other comprised of 30 outlier loci. Results from all analyses and using both data sets indicated a high level of genetic differentiation between specimens from the Gulf of Mexico and specimens from the U.S East Coast. Using the outlier data set, a low but significant level of genetic differentiation was also found among specimens from the U.S. East Coast, with a subtle break near the North Carolina and South Carolina border. Genetic differences along the U.S. East Coast were spatially autocorrelated, indicating a latitudinal genetic gradient. The level of observed genetic differentiation between the Gulf of Mexico and the U.S. East Coast is likely due to physical barriers such as Florida and the Gulf Stream current, while the subtle structure along the U.S. East Coast is likely attributable to isolation caused by dispersal limitations and local temperature preferences. The results from this investigation of Clearnose Skate population structure can be used to better monitor and manage this vulnerable elasmobranch.
... Ces deux espèces ont souvent été confondues. Si Bigelow et Schroeder (1953) d’une part, Blache, Cadenat et Staucii (1970) d’autre part, semblent considérer T. (T.) mackayana comme dis¬ tincte de T. (T.) nobiliana, il apparaît, comme l’ont souligné Quiîro et coll. (1976), que les illustrations publiées sous le nom de T. noèiZianaparCADENAT (1950( ) et parPoLL(1951 corres¬ pondent à la figure qui accompagne la description de T. mackayana par Metzelaar (1919). ...
... Notons que chez ces dernières la cuspide est très légèrement incurvée vers l’extérieur ( fig. 6). Le nombre de dents semble augmenter progressivement avec la taille, ce qui explique les chiffres souvent différents donnés par les auteurs : 36/34 (Garman, 1913), 38/38 chez les jeunes et 48/46 à 66/61 chez les adidtes (Bigelow et Schroeder, 1953), 66/66 (Tortonese, 1956), 38-66/38-61 (Bini, 1967). Nous avons fait des observations identiques pour les spécimens des côtes tunisiennes mais le phénomène est encore plus marqué après la maturité sexuelle comme l’indiquent la figure 7 et le tableau I qui montrent la relation existant entre la taille et le nombre de rangées de dents de la mâchoire supérieure. ...
... CCNHM 5584 and ChM PV 9834 are close in morphology and size to the gigantic holotype specimen of "Ceratoptera unios" (ANSP 8069). The flat dermal buckler (CCNHM 5583) and the smaller caudal buckler (ChM 5075.2) are close in morphology to B. centroura, owing to the deep radial grooves and ridges around the crown (Bigelow and Schroeder 1953;Purdy et al. 2001), and given their large size, are probably referable to Bathytoshia or B. centroura, following Purdy et al. (2001). It is possible, if not likely, that the suite of unusually large dermal tubercles and bucklers (including "Ceratoptera unios") represent the same taxon-possibly B. centroura. ...
... Few anatomical studies of extant dasyatid dermal elements have been published, limiting the capacity for evaluating whether these may belong to a different species of dasyatid (e.g., Bor et al. 2012). For example, other sympatric species like Dasyatis americana, Dasyatis guttata, Dasyatis sabina, and Fontitrygon geijskesi also possess mid-dorsal tubercles, albeit not as large (relatively or absolutely) as in B. centroura (Bigelow and Schroeder 1953). Descriptions, measurements, illustrations, or photographs are not available for most of these, and only preliminary data on the dermal elements of B. centroura are available from a single specimen (Silas and Selvaraj 1985)-although this specimen was likely misidentified and belongs to a different, as yet undetermined dasyatid (Weigmann 2016). ...
batoid dermal elements is an isolated fossil tubercle originally interpreted as a manta ray caudal stinger and named Ceratoptera unios Leidy, 1877 from an unknown locality near Charleston, South Carolina. Though recently considered to be a stingray (Dasyatidae), the lack of stratigraphic provenience for the specimen has hampered attempts to identify it. A new collection of gigantic dermal tubercles and bucklers from the Lower Pleistocene Waccamaw Formation of South Carolina includes mid-dorsal tubercles similar in morphology to “Ceratoptera unios” and dermal bucklers similar in morphology to those of the extant roughtail stingray Bathytoshia centroura (Mitchill, 1815). Mid-dorsal tubercles and bucklers suggest gigantic stingrays in excess of 3 m disc width. These new specimens suggest that C. unios may have originated from upper Pliocene or Pleistocene deposits, and possible synonymy with Bathytoshia centroura, pending careful study of extant dasyatid dermal elements.
... Consequently, certain extreme deformities were mistakenly identified as new species 4 . An illustrative example is Day's classification of an abnormal Gymnura poecilura specimen as a distinct species, which he named Ceratoptera chrenbergii 5,6 . Over recent decades, several studies have documented morphological abnormalities in elasmobranchs, particularly in skates and rays 3,7−9 . ...
This study documents the morphological deformities in Brevitrygon imbricata (Bengal whipray) and Chiloscyl-lium arabicum (Arabian carpetshark) from the Indian coast. Notable deformities include a rostral irregularity in B. imbricata, resulting in a horn-like expansion, and a bifurcated second dorsal fin in C. arabicum. These findings highlight the need for further research into the causes of such deformities, which could be linked to various environmental stressors. The study emphasises the importance of monitoring these deformities for conservation and fisheries management.
... Rays were identified using taxonomic references (Bigelow and Schroeder 1953;Last et al. 2016;Petean et al. 2020), with the following species recorded: Hypanus guttatus (Bloch and Schneider, 1801), Gymnura aff. micrura (Bloch and Schneider, 1801), Hypanus geijskesi (Boeseman, 1948), Styracura schmardae (Werner, 1904), Aetobatus narinari (Euphrasen, 1790), Hypanus berthalutzae Petean et al. 2020, andPseudobatos percellens (Walbaum, 1792). ...
The behavioral plasticity of non-marine elasmobranch species allows these animals to strategically inhabit areas where salinity aligns with their physiological needs. Thus, this study aimed to investigate habitat use by rays in an Amazonian estuary, following a categorization of non-marine species based on the type of environment in which critical life history phases occur. Data on the capture of ray species in fishing weirs were acquired through a monitoring program conducted from March 2011 to April 2012. One hundred and forty-five coastal-estuarine rays, representing seven species, were sampled over 1 year in the estuary, across a salinity range from 12.9 to 41.3 ppt (26.8 ± 11.6 ppt). The dominant presence of neonates and juveniles, constituting approximately 70% of the total rays captured year-round, is noteworthy. Additionally, the presence of pregnant females with embryos at various developmental stages indicates the importance of the study area for the life cycle of various elasmobranch species. Our data suggest that Hypanus guttatus and Hypanus geijskesi fit into the estuarine generalist category, and Gymnura aff. micrura fits into the non-marine transient category. We identify salinity as a key driver of ray temporal distribution within the Amazonian coast, a crucial region for elasmobranch conservation. Future studies should, therefore, aim to understand how climate change might impact elasmobranch habitat use in this region.
... The smalltooth sawfish (Pristis pectinata) was the third identified batoid of the order Rhinopristiformes from among the analyzed specimens. While once found on both sides of the Atlantic Ocean (e.g., Bigelow and Schroeder, 1953), this species is now restricted to waters surrounding Florida, particularly within the Everglades National Park, and the Bahamas (Carlson et al., 2013;Simpfendorfer and Wiley, 2005;Wiley and Simpfendorfer, 2007). The species is present all year in south Florida coastal waters, and individual animal size tends to correlate with habitat preferences; with small individuals or juveniles observed in shallow coastal habitats, such as mangroves and estuaries, while larger juveniles or adults are observed among deeper or open waters (Waters et al., 2014). ...
Introduction
Elasmobranchs, such as sharks and rays, are among the world’s most endangered vertebrates, with over 70% loss in abundance over the past 50 years due to human impacts. Zooarchaeological baselines of elasmobranch diversity, distribution, and exploitation hold great promise for contributing essential historical contexts in the assessment of contemporary patterns in their taxonomic diversity and vulnerability to human-caused extinction. Yet, the historical ecology of elasmobranchs receives relatively less archaeological attention compared to that of ray-finned fishes or marine mammals, largely due to issues of taxonomic resolution across zooarchaeological identifications.
Methods
We explore the use of Zooarchaeology by Mass Spectrometry (ZooMS) for species identification in this unstudied group, using an archaeological case study from the marine environments of the Florida Keys, a marine biodiversity hotspot that is home to an array of elasmobranch species and conservation efforts. By comparison with 39 modern reference species, we could distinguish 12 taxa within the zooarchaeological assemblage from the Clupper archaeological site (Upper Matecumbe Key) that included nine sharks, two rays and a sawfish.
Results and discussion
The results indicate that, through additional complexity of the collagen peptide mass fingerprint, obtained due to the presence of the cartilaginous type II collagen, ZooMS collagen peptide mass fingerprinting provides exceptionally high taxonomic resolution in this group, yielding species-level identifications in all cases where sufficient reference material was used. This case study also highlights the added value of ZooMS for taxa that are more difficult to distinguish in zooarchaeological analyses, such as vertebrae of the Atlantic sharpnose shark (Rhizoprionodon terraenovae) and the hammerhead sharks (Sphyrna spp.) in the Florida Keys. Therefore, the application of collagen peptide mass fingerprinting to elasmobranchs offers great potential to improve our understanding of their archaeological past and historical ecology.
... External morphometric measurements were taken by vernier caliper to one tenth of a millimeter (mm) from the RV 'Vityaz' specimens prior to preservation and from the other two specimens preserved in 70% ethanol or 4% formaldehyde. Measurements were taken between perpendicular lines where relevant and largely following Bigelow and Schroeder [25]. Exceptions: prenasal snout length from snout tip to transverse line through anterior edge of nostrils, and orbit plus spiracle length after Clark [26]; ventral head length from snout tip to transverse line through fifth gill slits after Ishiyama [27]; tail and nasal curtain measurements after Hubbs and Ishiyama [28]; spiracle length measured diagonally as aperture proper; length of pelvic lobes measured from the point of articulation of the anterior lobe according to Stehmann [29]. ...
Simple Summary
Skates of the genus Leucoraja Malm, 1877, are small to medium-sized skates that usually have a short, obtusely angled snout. Until now, 14 valid species of this genus have been identified mostly in the Atlantic, but also in the Indian Ocean. In the 1970s and 1980s, a total of eight specimens of an unusual skate species were collected by researchers working on the Madagascar Ridge, an elevated area of seabed in the southwestern Indian Ocean. Despite their long snouts, the specimens could unambiguously be assigned to the genus Leucoraja due to the typical features of their claspers. Comparisons with congeners clearly indicated that these remarkable specimens represent a species new to science. It can easily be distinguished from all 14 congeners by the long and acutely pointed snout. Furthermore, it appears to occur only on the Madagascar Ridge, distant from the known distribution areas of all congeners, and shows several unique aspects in its clasper morphology. Due to the importance of the clasper features, 3D modeling is introduced as a new tool for the visualization of clasper characters. The newly described species is named Brown longnose skate.
Abstract
A remarkable new deep-water skate, Leucoraja longirostris n. sp., is described based on eight specimens caught during different expeditions to the southern Madagascar Ridge in the southwestern Indian Ocean. The new species differs from all congeners by its remarkably long and acutely angled snout (horizontal preorbital length 17.2–22.6% TL vs. 8.5–11.9% TL and 4.2–6.1 vs. 1.7–3.5 times orbit length, snout angle 65–85° vs. 90–150°). Furthermore, it is apparently endemic to the Madagascar Ridge, distant from the known distribution areas of all congeners. In addition to L. fullonica and L. pristispina, L. longirostris n. sp. is also the only species with plain dorsal coloration. Furthermore, the new species is the only Leucoraja species with an external clasper component dike and, besides L. wallacei, the only one with four dorsal terminal (dt) cartilages. The shape of the accessory terminal 1 (at1) cartilage with four tips is also unique within the genus. A new approach for the visualization of the clasper characters is introduced based on 3D models of all skeletal and external features. This enables a much easier and much more precise interpretation of every single clasper component, of the entire structure, and, in particular, the relationship between external features and skeletal cartilages. A new English translation of the first diagnosis of Leucoraja is provided, along with a revised generic diagnosis and a key to the species of Leucoraja in the Indian Ocean.
... However, their phylogenetic position among chondrichthyans remains uncertain (Séret 1986). Some authors consider them as the sister group to sharks, which represent the Selachii clade (Müller and Henle 1841;Günther 1870;Regan 1906;Garman 1913;White 1937;Berg 1940;Bigelow and Schroeder 1953;Norman 1966;Da Cunha et al. 2017;Kousteni et al. 2021), while others suggest that batoids are nested within Selachii (Goodrich 1909;Jordan 1923;Bertin 1939;Arambourg and Bertin 1958;Compagno 1973Compagno , 1977Shirai 1996;Carvalho 1996;Aburatani et al. 2020). ...
... Photographs of the sample were taken and its identification was confirmed based on Last et al (2016a) and Kumar et al (2021). Morphological measurements of specimen were based on batoid measurements proposed by Bigelow and Schroeder (1953), Compagno and Roberts (1982), Manjaji (2004), which are based on modifications of Compagno J. Exp. Zool. ...
... Ribeiro-Prado et al. (2008) studied the Pteroplatytrygon violacea (Pelagic stingray) species abnormality of deep irregular curves of the pectoral fins with its head collected from the off coast of south-eastern Brazil, which corroborates with the present study. The absence of the fused and irregular curve on the pectoral fin was considered as congenital disorders and it affects the secondary growth stages of embryos in elasmobranchs; therefore, deformity occurred at the initial stages of ontogeny (Bigelow and Schroeder, 1953;Rosa et al., 1996). Based on the earlier reports and the current record on the deformity of M. bineeshi, it may be due to their birth defects, and its congenital abnormalities might be due to the environmental degradation of endogamy, parasites and huge pollutants that affected their entire life cycle (Tortonese, 1956;Klumpp et al., 2002;Sari et al., 2008;Kelly et al., 2009;Blanco-Parra and Niño-Torres, 2011;Escobar-Sanchez et al., 2009;Barrera-García et al., 2012). ...
... The total length of specimens was taken from tip of snout to caudal fin end (TL) and measured to the nearest millimeter. Identification of specimens, descriptions, terminology for morphometric characters, external and morphometric measurements were taken following standard taxonomic works 3,4,5 . ...
A species of torpedo electric ray, Torpedo polleni (Bleeker, 1865) has been reported for the first time from Indian waters. Six specimens of T. polleni measuring 147-397 mm TL were collected from shrimp trawl by-catches at Visakhapatnam, central eastern coast of India. The present paper provides description and comparison of morphometric data of T. polleni with closely resembling species of genus Torpedo thus helping in clearing taxonomic ambiguities. The present study suggests that T. polleni (Bleeker, 1865) with 6-8 knob-like papillae on the posterior margin of spiracle, the central papilla being larger, distance between eye and spiracle less than eye diameter, nasal curtain short and wide, its length more than half the length of inter narial width, first dorsal fin originating entirely above the pelvic fin base and base ending little beyond the pelvic fin, dorsal surface showing ornate appearance with close set of brownish-black spots, few spots very closely set or joined together forming vermiculations and dark brown lines is a valid species.
... The yellow stingray, Urobatis jamaicensis (Cuvier, 1816) is the only member of the genus found in the Western Atlantic and Caribbean waters, with a latitudinal range from Florida to Venezuela (Lesniak et al. 2015). However, it also has been reported in North Carolina, south to Brazil, and in the Gulf of Mexico (Bigelow and Schroeder 1953;Robins et al. 1986;Hoese and Moore 1998;McEachran and Fechhelm 1998;McEachran and de Carvalho 2002;Spieler et al. 2013). ...
Eight specimens of Urobatis jamaicensis were collected from four localities of the Yucatan Peninsula, Mexico, of which four specimens were infected with cestodes of two new species of Acanthobothrium . Acanthobothrium garciaprietoi sp. nov. differs from congeners by a combination of characters including the size of the scolex and bothridia, length of the cephalic peduncle, length of the axial and abaxial prongs and total length of the abaxial prongs of the hooks, size of the cirrus sac and testes in mature proglottids, and the total number of proglottids. The most prominent characteristic distinguishing A. pulidofloresae sp. nov. from other species of the Atlantic Ocean/Caribbean Sea/Gulf of Mexico is the form of the scolex, which has the “clover leaf” configuration. In addition, it can be distinguished by the total length of the worm, total number of proglottids, small accessory suckers, the form of the bothridia, length of the axial and abaxial prongs and total abaxial prong length of hooks, and the number of testes. According to the current category scheme, A. garciaprietoi sp. nov. and A. pulidofloresae sp. nov. , belong to categories 1 and 5, respectively.
... Sawfishes (family Pristidae) are a small group of large, shark-like rays that occur in nearshore habitats of tropical and subtropical waters, including estuarine and freshwater ecosystems (Bigelow & Schroeder, 1953;Poulakis & Seitz, 2004). They are characterized by an elongated, tooth-studded rostrum used for feeding and defence (Wueringer et al., 2009). ...
The Bahamas is among the last remaining refuges for the Critically Endangered smalltooth sawfish, Pristis pectinata , and the presence of a distinct ‘beacon of hope’ population on Andros Island may prove critical to their recovery. Although legislation in The Bahamas protects sharks from exploitation, no such national protection exists for rays, which include sawfishes. Targeted efforts to protect essential habitats coupled with community‐led conservation actions provide a path forward for sawfish conservation and recovery.
Structured interviews were conducted in 2021 ( n = 77) with community members that frequent Andros waters to describe the temporal and spatial patterns of sawfish distribution in Andros, and to identify key regions or habitats for sawfish‐specific monitoring and potential protection.
Sawfish encounters ( n = 99) included all life stages and were located throughout coastal and tidal waters of Andros. Comparable numbers of animals were encountered along both coastlines, predominantly on shallow (<2 m), muddy flats close to shore (<1 km). Most notable were encounters with young‐of‐the‐year sawfishes in new regions of Andros, indicating the potential discovery of undocumented nursery habitats. Although most encounters were sightings, 22% ( n = 20) of the sawfishes were caught, with just under half of these harvested for food, bait, and/or to keep the rostrum as a decorative item.
There is an urgent need for more expansive protection and monitoring of smalltooth sawfishes across their range in Andros and improved education and outreach to prevent further harvest. Recommendations include: (i) the formal development of a national strategy for sawfish conservation; (ii) adding sawfish to the existing shark sanctuary to provide national protective measures; and (iii) community‐led outreach and education activities to develop and lead conservation initiatives, including ecotourism and wildlife guiding and a Bahamian sawfish reporting network.
... yes on their dorsal surface of the body whereas they mouth and five (5) gill slits are present on the ventral side of the specimen's body. Their tail is narrow which is sometimes as long as their body's length whereas in some species of rays, the tail is double of their body length, the anal fins are totally absent in all the species of Rajiformes (Bigelow and Schroeder. 1953). Rays are the species which are found worldwide most commonly in the tropical, subtropical and in the temperate waters. All the species of rays have whip like tail and mostly the tails are with the venomous spine which can harm to the humans as well. The distinguish between female specimen and male specimen can be done easily as the ma ...
This paper presents the updated and brief information about five
(5) ray species found among catches landed in the Karachi Fish Harbor (KFH) 24.8491° N, 66.9761° E. Surveys were made during
February 2015 and March-April 2019 at the KFH, situated at West Wharf, Karachi. During fields, subjected ray species were observed
in very small quantities, which have been recognized as rare species of ray faun seen on the site. Observed species were identified as
Aetobatus ocellatus, Gymnura poecilura, Himantura uarnak, Mobula kuhlii and Pastinachus sephen. Mobula kuhlii All five species
have been recognized as endangered species and have been listed in IUCN red list of endangered species. Despite the fact, still these
species often caught by fishermen and sold in market. Unfortunately, there is no check and balance thus there is an utmost need to take
corrective measures to conserve these species by implementing regulations.
... Fecundity of 23 eagle ray species ranges from 1 to 12 with 14 species less than 2 (Figure 14A), putting the relatively high fecundity of Naru eagle rays into phylogenetic perspective. From an anatomical perspective, fecundity for Myliobatidae and Aetobatidae species with paired uteri was higher compared with Rinopteridae and Mobulidae species with one functional uterus and usually, only one offspring (Bigelow and Schroeder, 1953;Notarbartolo-di-Sciara and Serena, 1988;White et al., 2006;Mendonça et al., 2012). The Naru eagle ray is the only Aetobatid species with paired uteri and females had higher fecundity and smaller neonates at birth than similarly sized congener females ( Figure 14B). ...
Batoids comprise five of the seven most threatened families of sharks and rays. The East Asian endemic Naru eagle ray Aetobatus narutobiei is a large bodied ray whose estuarine habitat overlaps with an economically valuable bivalve fishery. In response to decreased bivalve yields, the government initiated a predator control program and as a result, Naru eagle rays have faced intense and targeted fishing pressure during the last two decades. The long-term impacts of the predator control program on the population of rays and bivalves and their balance in the ecosystem are unknown because the life history of the Naru eagle ray has not been characterized. To begin to fill these critical knowledge gaps, the reproductive life history of the Naru eagle was described. Females mature at a larger size than males and require nearly twice as many years to reach maturity (DW50, 952.0 mm vs. 764.2 mm; Age50, 6.0 years vs. 3.5 years). Both males and females reproduce annually and their reproductive cycles are synchronized and seasonal. Females have a single ovary and paired uteri, are viviparous, and reproduce via matrotrophic histotrophy. Mating occurs in August and September and gestation lasts approximately 12 months including a 9.5-month diapause that begins soon after mating and ends in June of the following year, leaving 2.5 months for embryos to complete development. Fecundity ranged from 1 to 7 embryos per brood (n = 158, mean ± SD = 3.36 ± 1.26) and was positively correlated with female disc width (linear regression; F = 105.73, d.f. = 151, P < 0.05). Naru eagle rays are vulnerable to overfishing because of their low fecundity, long reproductive cycle and long time to reach sexual maturity. Obligate embryonic diapause during overwintering and seasonal migrations is a survival strategy that benefits the adults and neonates. This research is a valuable resource to help guide science-based management, conservation and protection of the endemic Asian A. narutobiei and its nursery areas.
... Assim como no Brasil, devido ao declínio reportado nas capturas e por suas características reprodutivas, a espécie é considerada globalmente "Em Perigo" (Pollom et al., 2020). Myliobatis goodei possui ampla distribuição, ocorrendo desde os EUA até o sul da Argentina (Bigelow & Schroeder, 1953, McEachran & Carvalho, 2002, em profundida-des de até 181 m (Menni & Stehmann, 2000). Possui LD máxima registrada de 99 cm, com maturação das fêmeas por volta dos 70 cm e dos machos entre 45 e 55 cm (McEachran & Carvalho, 2002). ...
Monitoramento de pescarias industriais de arrasto-de-fundo por meio de observadores científicos na Plataforma Continental e Talude do sul do Brasil entre 2015 e 2017 DOCUMENTO TÉCNICO Revista CEPSUL-Biodiversidade e Conservação Marinha, 10: e2021007 Resumo. Foram monitorados, entre 2015 e 2017, 225 dias de mar e 775 lances nas pescari-as industriais de arrasto-de-parelha, arrasto-duplo para linguado, arrasto-duplo para abró-tea/merluza e arrasto-simples para cabrinha, a partir do embarque de observadores científi-cos do CEPSUL/ICMBio no sul do Brasil, cujo objetivo foi obter informações sobre as opera-ções e áreas de pesca, assim como das capturas, principalmente das espécies ameaçadas de extinção, quase ameaçadas e com dados insuficientes. No arrasto-de-parelha, foram captu-radas 201,565 t (três viagens; 184 arrastos), sendo estocadas 25 espécies, principalmente corvina, castanha, goete e maria-mole. A "mistura" foi composta por 68 espécies e a captura rejeitada média em peso foi de 36%. No arrasto-duplo para linguado, capturou-se 94,350 t (duas viagens; 179 arrastos), com mais de 25 espécies estocadas; sendo as principais: lingua-do, castanha, maria-mole e cabrinha. A "mistura" variou em cada viagem, apresentando a captura rejeitada média em peso de 62%. No arrasto-duplo para abrótea/merluza, foram capturadas 404,087 t (quatro viagens; 306 arrastos). As principais espécies foram abrótea-olhuda, merluza, peixe-sapo e congro-rosa e a "mistura" variou entre viagens, com composi-ção significativa de elasmobrânquios. A captura rejeitada média em peso foi de 22%. No ar-rasto-simples para cabrinha, foram capturadas 245,885 t (três viagens; 106 arrastos), com 17 espécies estocadas, principalmente cabrinha, emplastros (maioria Rajiformes), linguado e castanha. A captura rejeitada média em peso foi de 27%. Observou-se grande diversidade de espécies descartadas, algumas ameaçadas de extinção, indicando ser fundamental a adoção de medidas de conservação participativas e integradas com as políticas de gestão pesqueira
... Assim como no Brasil, devido ao declínio reportado nas capturas e por suas características reprodutivas, a espécie é considerada globalmente "Em Perigo" (Pollom et al., 2020). Myliobatis goodei possui ampla distribuição, ocorrendo desde os EUA até o sul da Argentina (Bigelow & Schroeder, 1953, McEachran & Carvalho, 2002, em profundida-des de até 181 m (Menni & Stehmann, 2000). Possui LD máxima registrada de 99 cm, com maturação das fêmeas por volta dos 70 cm e dos machos entre 45 e 55 cm (McEachran & Carvalho, 2002). ...
Foram monitorados, entre 2015 e 2017, 225 dias de mar e 775 lances nas pescarias industriais de arrasto-de-parelha, arrasto-duplo para linguado, arrasto-duplo para abrótea/merluza e arrasto-simples para cabrinha, a partir do embarque de observadores científicos do CEPSUL/ICMBio no sul do Brasil, cujo objetivo foi obter informações sobre as operações e áreas de pesca, assim como das capturas, principalmente das espécies ameaçadas de extinção, quase ameaçadas e com dados insuficientes. No arrasto-de-parelha, foram capturadas 201,565 t (três viagens; 184 arrastos), sendo estocadas 25 espécies, principalmente corvina, castanha, goete e maria-mole. A “mistura” foi composta por 68 espécies e a captura rejeitada média em peso foi de 36%. No arrasto-duplo para linguado, capturou-se 94,350 t (duas viagens; 179 arrastos), com mais de 25 espécies estocadas; sendo as principais: linguado, castanha, maria-mole e cabrinha. A “mistura” variou em cada viagem, apresentando a captura rejeitada média em peso de 62%. No arrasto-duplo para abrótea/merluza, foram capturadas 404,087 t (quatro viagens; 306 arrastos). As principais espécies foram abrótea-olhuda, merluza, peixe-sapo e congro-rosa e a “mistura” variou entre viagens, com composição significativa de elasmobrânquios. A captura rejeitada média em peso foi de 22%. No arrasto-simples para cabrinha, foram capturadas 245,885 t (três viagens; 106 arrastos), com 17 espécies estocadas, principalmente cabrinha, emplastros (maioria Rajiformes), linguado e castanha. A captura rejeitada média em peso foi de 27%. Observou-se grande diversidade de espécies descartadas, algumas ameaçadas de extinção, indicando ser fundamental a adoção de medidas de conservação participativas e integradas com as políticas de gestão pesqueira no Brasil.
... External morphometric measurements were taken using a vernier caliper to one-tenth of a millimeter (mm) from the specimens preserved in 70% ethanol. Measurements were taken between perpendicular lines where relevant and largely following Bigelow and Schroeder (1953). Exceptions: prenasal snout length from snout tip to transverse line through anterior edge of nostrils, and orbit plus spiracle length after Clark (1926); ventral head length from snout tip to transverse line through fifth gill slits, clasper length, and eyeball horizontal diameter after Ishiyama (1958); dorsal head length medially from snout tip to occipital joint, clasper length from front tip of hemal spine to extreme tip of clasper, as well as tail and nasal curtain measurements after Hubbs and Ishiyama (1968); spiracle length measured diagonally as depression and as aperture proper; length of pelvic lobes measured from point of articulation of anterior lobe according to Stehmann (1985); width across pelvic-fin base between anterior points of articulation, anterior pelvic lobe base width, width across posterior pelvic lobe as maximum width across expanded lobe, and head width at anterior margin of orbits, as well as disc and preorbital snout length direct (point-to-point) after Last and Séret (2008). ...
A new deep-sea softnose skate, Notoraja hesperindica, is described based on six specimens caught in 1230–1600 m depths off southern Mozambique and northwestern Madagascar in the western Indian Ocean. The new species is a medium-sized species of Notoraja Ishiyama, 1958 reaching a total length of at least 539 mm. It is the only Notoraja species known from the western Indian Ocean and differs from most congeners in the intense dark blue-grayish coloration. The only congeners with similarly vibrant coloration are Notoraja azurea McEachran & Last, 2008 from off southern Australia and Notoraja sapphira Séret & Last, 2009 from the Norfolk Ridge (Coral Sea and Tasman Sea), which differ from the new species in a shorter and more obtusely angled snout, a shorter head, a shorter disc, and smaller dorsolateral tail thorns, as well as more predorsal tail and total predorsal vertebrae and more pectoral-fin radials. The large dorsolateral tail thorns also distinguish the new species from most congeners except for the eastern Pacific Notoraja martinezi Concha, Ebert & Long, 2016, which has even larger, randomly patterned dorsolateral tail thorns that give the tail a barbedwire-like appearance. This congener further differs from N. hesperindica sp. nov. in the absence (vs. presence) of malar thornlets, fewer median tail thorns, a shorter snout, more tooth rows in upper and lower jaws, and more pectoral radials. A key to the species of Notoraja in the Indian Ocean is provided.
... 65. Raia stabuliforis: von Bonde & Swart, 1923: 12. Raja batis: Norman, 1935Fowler, 1941: 385;Bigelow & Schroeder, 1953: 146. Raja pullopunctata: Smith, 1964Hulley, 1966: 505, figs. ...
An annotated checklist of chondrichthyan fishes (sharks, batoids, and chimaeras) occurring in South African waters is presented. The checklist is the result of decades of research and on-going systematic revisions of the regional fauna. The chondrichthyan fauna of South Africa is one of the richest in the world with 191 species, comprising 50 families and 103 genera. It consists of 30 families, 64 genera, and 111 species of sharks; 17 families, 36 genera, and 72 species of batoids; and, 3 families, 5 genera, and 8 species of chimaeras. The most species-rich shark families are the whaler sharks Carcharhinidae with 20 species followed by the deepwater catsharks Pentanchidae with 13 species. The most species-rich batoid families are the hardnose stakes Rajidae with at least 21 species followed by the stingrays Dasyatidae with 13 species. This monograph represents the first detailed annotated checklist of chondrichthyans from South Africa in over 30 years.
... External morphometric measurements were taken by vernier caliper to onetenth of a millimeter (mm) from the specimens preserved in 70% ethanol. Measurements were taken between perpendicular lines where relevant and largely following Bigelow and Schroeder (1953). Exceptions: prenasal snout length from snout tip to transverse line through anterior edge of nostrils, and orbit plus spiracle length after Clark (1926); ventral head length from snout tip to transverse line through fifth gill slits, clasper length, and eyeball horizontal diameter after Ishiyama (1958a); dorsal head length medially from snout tip to occipital joint, as well as tail and nasal curtain measurements after Hubbs and Ishiyama (1968); spiracle length measured diagonally as depression and as aperture proper; length of pelvic lobes measured from point of articulation of anterior lobe according to Stehmann (1985); width across pelvic-fin base between anterior points of articulation, anterior pelvic lobe base width, width across posterior pelvic lobe as maximum width across expanded lobe, head width at anterior margin of orbits, as well as disc and preorbital snout length direct (point-to-point) after Last and Séret (2008). ...
The dark-mouth skate, Raja arctowskii Dollo, 1904 from Antarctic waters is an extraordinary case in skate taxonomy. For more than 100 years, this species has been known only from three empty egg capsules and the species as such has remained undescribed due to the lack of specimens that could be assigned to Dollo’s small capsules. Since trawled egg capsules and an egg capsule containing a near-term embryo became available, it finally was possible to connect specimens with the empty egg capsules and completely describe Dollo’s R. arctowskii with detailed external morphology, skeletal features, clasper morphology, and clasper skeleton and assign it to the genus Bathyraja Ishiyama, 1958a. Bathyraja arctowskii is one of the smallest known species of Bathyraja, attaining only a 61 cm total length (TL). It is characterized by an at least partly, usually completely medium to dark grayish pigmented mouth cavity, as well as the often dark underside of the nasal curtain from very small juvenile stages onwards. It further differs from most congeners in Antarctic and Subantarctic waters in the absence of thorns on the dorsal disc. It appears to be a wide-ranging, circumantarctic species found in the Atlantic, Pacific, and Indian Ocean sectors of the Southern Ocean. The species seems to be locally common at least in the Atlantic sector, with up to 94 juvenile to subadult specimens caught in one single haul.
... The species has a muscular body morphology adapted for long-distance travel, including large pectoral fins suited for oscillatory swimming behavior (Parson et al. 2011). These physical aspects of A. narinari, as well as its occurrence in remote islands such as Bermuda, have led to assumptions of highly migratory behavior in this species (Bigelow and Schroeder 1953). While multiple tagging studies have been conducted on A. narinari in Bermuda and The Bahamas (Silliman and Gruber 1999;Ajemian et al. 2012;Ajemian and Powers 2014), these have been limited in temporal scale (< 3 months). ...
Basic distribution and movements of elasmobranch species, particularly mesopredatory rays, remain relatively unknown. This is especially true for the whitespotted eagle ray (Aetobatus narinari), a protected species in Florida with poorly described migratory and habitat use patterns. Passive acoustic telemetry was used to reveal multi-scale spatial patterns of A. narinari in Florida waters. Between 2016 and 2018, 54 rays were fitted with acoustic transmitters and tracked via collaborative telemetry networks. Movement patterns between the Atlantic and Gulf coast individuals were distinct; a majority of Gulf coast tagged A. narinari exhibited migratory or transient behaviors while most Atlantic coast tagged individuals remained resident in the Indian River Lagoon (IRL). On both coastlines, water temperatures during times when A. narinari were present were significantly warmer (mean = 27.8 °C) compared to temperatures when A. narinari were absent (mean = 24.9 °C), suggesting temperature may be a major abiotic factor influencing migration patterns. Ontogenetic shifts in habitat use were evident along the Atlantic coast in the IRL, but not along the Gulf coast. Immature rays spent significantly more time (mean = 91.5%) inside the IRL compared to mature counterparts (mean = 60.2%). This is the first multiyear study to examine large-scale movements of A. narinari in U.S. waters and results may be important for adaptive management strategies throughout this species’ range. Importantly, our work suggests potential sub-population structuring of A. narinari may be occurring more than previously considered within Florida, which has significant conservation implications for this species.
... This suggests that the ingestion of microplastics by stingrays and sharks may eventually also affect human food safety and health (Van Cauwenberghe and Janssen, 2014). The Longnose stingray, Hypanus guttatus (Bloch and Schneider, 1801), a species of the family Dasyatidae, is an opportunistic, benthonic predator (Gianeti et al., 2019;Last et al., 2016), distributed from the southern Gulf of Mexico to southeastern Brazil (Bigelow and Schroeder, 1953;Rosa and Furtado, 2016). This species may reach up to 2 m in disc width and is very common as by-catch in the artisanal and industrial fisheries along the northern and northeastern coasts of Brazil (Rodrigues et al., 2020;Tagliafico et al., 2013). ...
The present study documents, for the first time, the ingestion of microplastics (MPs) by Longnose stingrays in theWestern Atlantic Ocean. We examined 23 specimens ofHypanus guttatusfrom the Brazilian Amazon coast andfound microplastic particles in the stomach contents of almost a third of the individuals. Fibers were the mostfrequent item (82%), blue was the most frequent color (47%) and Polyethylene Terephthalate (PET) was themost frequent polymer recorded (35%), as identified by 2D imaging - Fourier Transform Infrared (FTIR). Theingestion of microplastics by Longnose stingray has not been previously recorded. The findings of the presentstudy thus provide an important baseline for future studies of microplastic ingestion by dasyatid rays and otherbatoid species in the Atlantic Ocean, and contribute to the broader understanding of the spatial and temporaldimensions of the growing problem of plastic pollution in aquatic ecosystems and organisms.
Shark declines may cause trophic cascades, which is partially dependent on how
sharks influence prey abundance and behaviour. Rays are mesopredators that
play a unique role in ecosystems as bioturbators. My dissertation investigates
whether sharks induce changes in ray sightings, behaviour, and habitat use
across multiple spatial and temporal scales. First, I reviewed the ray ecology
literature and found limited evidence for risk-induced ray trait responses (Chapter
1). Next, using a baited remote underwater video station (BRUVS) survey, I
found that southern stingray (Hypanus americanus) sightings were negatively
associated with shark abundance throughout the tropical Western Atlantic Ocean
(Chapter 2). Other important predictors of southern stingray sightings in the
region included habitat complexity, geomorphology, and bottom fishing gear. At a
smaller spatial scale inside the Glover’s Reef Marine Reserve in Belize, a
BRUVS survey revealed southern stingray sightings and behaviour remained
stable between 2009 – 2019 despite a concurrent decline in the relative
abundance of Caribbean reef sharks (Carcharhinus perezi) (Chapter 3). Habitat
complexity explained southern stingray sightings and behaviour on BRUVS,
which may be due to their preference for soft bottom habitats and/or because we
are less likely to detect stingrays on BRUVS in areas with high reef relief.
Passive acoustic telemetry showed Caribbean reef and lemon (Negaprion
brevirostris) sharks use shallow lagoon habitat, which was also the preferred
habitat of southern stingrays, suggesting it is unlikely a refuge from predators.
Finally, using accelerometry and hidden Markov models, I found that southern
stingray activity is crepuscular and nocturnal, with high individual variation
(Chapter 4). Southern stingrays were highly active in shallow water (<5 m), which
is likely associated with prey activity and availability. My findings emphasize the
context dependent nature of predation risk effects and the need to take a
multimethod approach to understand ray behaviour and habitat use.
Management of thorny skate (Amblyraja radiata) in the Northwest Atlantic has posed a conservation dilemma for several decades due to the species' lack of response to strong conservation efforts in the US Gulf of Maine and the Canadian Scotian Shelf, confusion over the relationship between two reproductive size morphs of differing life histories that are sympatric in the Northwest Atlantic, and conflicting data on regional population connectivity throughout the species' broader range. To better assess potential A. radiata regional population differentiation and genetic links to life‐history variation, we analysed complete mitochondrial genome sequences from 527 specimens collected across the species' North Atlantic geographic range, with particular emphasis on the Northwest Atlantic region. A high level of genetic diversity was evident across the North Atlantic, but significant genetic differentiation was identified between specimens inhabiting the Northwest (Gulf of Maine and Newfoundland) and Northeast (Greenland, Iceland, North Sea, and Arctic Circle) Atlantic. In the Northwest Atlantic, significant differentiation between the Gulf of Maine and Newfoundland regions was revealed; however, the overall level of differentiation was very low. No genetic difference was identified between the large and small reproductive morphs. The results of this study advance our understanding of A. radiata population structure in the North Atlantic but do not resolve all the questions confounding our understanding of the species' biology and evolutionary history.
Fishes represent the most diverse group of vertebrates, having inhabited the Earth for approximately 480 million years during which they evolved many specialised adaptations. One such adaptation is the evolution of a venom system, which has convergently arisen on at least 19 separate occasions across their evolutionary history. Venom evolution across fishes has taken two forms: chemical weaponisation of previously evolved defensive spines and the development of an oral venom system. Fish venoms have been shown to contain a myriad of toxin types, some of which may have pharmacological potential. However, due to the labile nature of many toxins, fish venom has not been extensively investigated compared to other venomous groups such as reptiles and arachnids. This review provides an updated scope of our current knowledge regarding the biology, biochemistry, and evolution of fish venom systems. It also attempts to provide a coherent assessment of the dated literature while seeking to address particular issues in order to drive fish venom research further.
One-third of all elasmobranchs (sharks and rays) are threatened with extinction. Euryhaline and estuarine generalist elasmobranchs are a group of 29 species that occupy non-marine environments during particular life-stages. These species are poorly known and disproportionately threatened, with 72.4% at risk of extinction or Data Deficient. A detailed knowledge of a species’ life history characteristics, movement ecology, habitat use, and population structure are required for the implementation of appropriate management and conservation measures. To date, research on euryhaline and estuarine species has lagged behind marine species. Here, a literature review and gap analysis of the euryhaline and estuarine species was conducted to identify gaps in 14 key parameters required for management. Of the 29 species, only the Bull Shark (Carcharhinus leucas) and the Largetooth Sawfish (Pristis pristis) had detailed information on a majority of parameters assessed. Nine species lack information on most parameters, while the Broadnose Wedgefish (Rhynchobatus springeri) lacks information on all but one of the parameters investigated. There is a high level of understanding of age- and size-at-maturity, size-at-birth, and growth for only five species, while nine species have estimates of natural mortality. Comprehensive reproductive biology data is unavailable for six species. Both short- and long-term movement ecology is well-understood for only two species, and habitat use for six species. Population structure has been studied in only eight species. Data on key life history parameters, population structure, and habitat requirements of the euryhaline and estuarine elasmobranchs are urgently required to develop appropriate management strategies and to secure populations.
Gymnurid rays are found in tropical, subtropical and temperate regions around the world, where they are associated with sandy or muddy bottoms in coastal areas, being easily distinguished from other rays by the width of the disc. In recent years, the systematics of this family have been revised extensively. However, there has been no comprehensive molecular review of the family based on an adequate sample of species and localities, which may have obscured the presence of distinct evolutionary lineages. The present study was based on samples of 12 of the 13 valid species of the genus Gymnura, which were used for a multilocus reconstruction of the evolutionary history of the family Gymnuridae. Our results indicate the existence of several cryptic gymnurid lineages, within the species Gymnura micrura, Gymnura lessae, Gymnura altavela, and Gymnura poecilura. Also, we indicate that only half of the species that compose the genus are known, as well their conservation status. The analyses also indicate that the gymnurids originated during the Paleocene, with events of dispersal and vicariance occurring through the formation of oceanographic barriers, and species diversification peaking during the Oligocene and Miocene. The results of the present study reinforce the need for a comprehensive revision of the systematics of the family, in particular the widely distributed species that are considered valid taxa, but may in fact represent different cryptic species. The inadequate classification of this cryptic diversity may have negative implications for the development of effective conservation measures.
Records about morphological abnormalities in rays of the genus Myliobatis are scarce worldwide.
In the present study, three specimens exhibiting different malformations were identified during the
monitoring of the reproductive biology of the Chilean eagle ray Myliobatis chilensis, conducted from
2017 to 2018 in the fishing port of Salaverry (northern Peru). The identified specimens included: (i) a
female with split pectoral fins, (ii) a male with an unfused-to-the-head pectoral fin, and (iii) a female
with a short and thick tail. Here we report and discuss the implications and likely causes of these first
three cases of morphological abnormalities in M. chilensis from the western Pacific.
Over the last few years, the morphology, taxonomy and systematics of the cartilaginous fish taxa of the two main sites of the Bolca Lagerstätte, Italy, (Pesciara and Monte Postale sites) have been extensively discussed in a series of papers, resulting in a complete revision of this neglected component of the Eocene Tethyan ichthyofauna. Here, we provide a comprehensive overview of the diversity, palaeoecology and palaeoenvironmental significance of the two chondrichthyan assemblages of the Pesciara and Monte Postale sites. The assemblages include 14 shark species (Lamniformes and Carcharhiniformes) and batoids (Torpediniformes, Rhinopristiformes, Myliobatiformes, Platyrhinidae and Zanobatidae), as well as a single putative chimaeriform. The Pesciara and Monte Postale sites are characterized by eight chondrichthyan taxa each, but the taxonomic compositions are distinctly different reflecting the dissimilarities in the overall composition of both fish assemblages. Palaeoecological interpretations and habitat preferences of the two chondrichthyan assemblages are consistent with previously hypothesized palaeoenvironmental settings based on sedimentological, palaeontological and geochemical evidence. The chondrichthyan assemblages of the two sites appear to be constituted by ecologically vicariant taxa, with both characterized by a predominance of benthic species with durophagous/cancritrophic feeding modes. Taxonomic composition, habitat preferences and palaeobathymetric analyses support the hypothesis that both assemblages occupied tropical marine shallow waters (likely up to 50 m deep) of the inner portion of the Lessini Shelf. The taxonomic composition of both sites is considerably different from that of any other contemporaneous Tethyan and Boreal chondrichthyan assemblages.
In 2018, the giant manta ray ( Manta birostris ) 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 15–30 °C. SDMs predicted high nearshore concentrations off Northeast 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 concentrations were predicted near 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.
Sampling two Onslow Bay sites bi-weekly from 1975–2010 using semi-balloon otter trawls 950 times collected two species of butterfly rays Gymnura altevala and Gymnura micrura: 37 were G. altevala and 244 were G. micrura. All but one male G. altevala were collected at the inshore site. Most specimens of both species were less than 1,000 mm disc width (DW). Most specimens were collected in April and October. Both species remain infrequent visitors of North Carolinian waters.
Ecotourism opportunities in the marine environment often rely heavily on provisioning to ensure the viewing of cryptic species by the public. However, intentional feeding of wildlife can impact numerous aspects of an animals' behavior and ecology. Southern stingrays (Hypanus americana) provisioned at Stingray City Sandbar (SCS) in Grand Cayman have altered diel activity patterns and decreased measures of health. This study looked at seasonal changes in stable isotope (SI) and fatty acid (FA) profiles of provisioned stingrays at SCS. Plasma δ 15 N was higher in male stingrays (11.86 ± 1.71‰) compared to females (10.70 ± 1.71‰). Lower values for δ 15 N in males and females were measured in October during low tourist season, suggesting stingrays may be forced to rely on native prey items to supplement the decreased amount of provisioned squid available during this time. Plasma FA profiles were significantly different between sexes and across sampling time points, with FAs 22:6n3, 16:0, 20:5n3, 18:1n3C, 18:0 and 18:1n9T contributing to dissimilarity scores between groups. Dietary FAs primarily contributed to differences between males and females lending further evidence to differences in foraging patterns at SCS, likely due to intraspecific competition. Further, canonical analysis of principal coordinates (CAP) analysis of FA profiles suggest similar diets during peak tourist season and differences in diet between males and females during the low season. This study demonstrates alterations in feeding ecology in stingrays at SCS which is of critical importance for effective management of the SCS aggregation. Ecotourism that consists of observing wildlife is a thriving business that generates billions of dollars to local economies 1-3. Non-consumptive wildlife based tourism has been well established in terrestrial settings, where opportunistic viewing of species is likely 4 , however, marine ecotourism is continually gaining popularity 1. The marine environment presents challenges to wildlife viewing as species spend most of their time below the surface, out of sight of hopeful tourists. In order to maximize the chances of encounters with marine species, tour operators often rely more heavily on provisioning 5. Although intentional feeding of wildlife can impact movement patterns, population size, reproduction, behavior, and health of these animals, many wildlife interaction operations continue the practice, often with unmeasured consequences 6. The distribution of food resources is one of the most important factors shaping behaviors of wild animals 7 , and not surprisingly, the provisioning of marine species greatly influences the behavior of marine wildlife 6,8. Provisioning of marine wildlife at tourist interaction sites often involves providing non-native prey items in unnatural quantities that affects the condition of fed animals 6,9. Despite the large-scale changes to diet, rate of consumption, and overall feeding ecology of marine wildlife that results from provisioning at tourist interaction sites, few of these features have been investigated 4,10,11 .
Ecotourism opportunities in the marine environment often rely heavily on provisioning to ensure the viewing of cryptic species by the public. However, intentional feeding of wildlife can impact numerous aspects of an animals' behavior and ecology. Southern stingrays (Hypanus americana) provisioned at Stingray City Sandbar (SCS) in Grand Cayman have altered diel activity patterns and decreased measures of health. This study looked at seasonal changes in stable isotope (SI) and fatty acid (FA) profiles of provisioned stingrays at SCS. Plasma δ 15 N was higher in male stingrays (11.86 ± 1.71‰) compared to females (10.70 ± 1.71‰). Lower values for δ 15 N in males and females were measured in October during low tourist season, suggesting stingrays may be forced to rely on native prey items to supplement the decreased amount of provisioned squid available during this time. Plasma FA profiles were significantly different between sexes and across sampling time points, with FAs 22:6n3, 16:0, 20:5n3, 18:1n3C, 18:0 and 18:1n9T contributing to dissimilarity scores between groups. Dietary FAs primarily contributed to differences between males and females lending further evidence to differences in foraging patterns at SCS, likely due to intraspecific competition. Further, canonical analysis of principal coordinates (CAP) analysis of FA profiles suggest similar diets during peak tourist season and differences in diet between males and females during the low season. This study demonstrates alterations in feeding ecology in stingrays at SCS which is of critical importance for effective management of the SCS aggregation. Ecotourism that consists of observing wildlife is a thriving business that generates billions of dollars to local economies 1-3. Non-consumptive wildlife based tourism has been well established in terrestrial settings, where opportunistic viewing of species is likely 4 , however, marine ecotourism is continually gaining popularity 1. The marine environment presents challenges to wildlife viewing as species spend most of their time below the surface, out of sight of hopeful tourists. In order to maximize the chances of encounters with marine species, tour operators often rely more heavily on provisioning 5. Although intentional feeding of wildlife can impact movement patterns, population size, reproduction, behavior, and health of these animals, many wildlife interaction operations continue the practice, often with unmeasured consequences 6. The distribution of food resources is one of the most important factors shaping behaviors of wild animals 7 , and not surprisingly, the provisioning of marine species greatly influences the behavior of marine wildlife 6,8. Provisioning of marine wildlife at tourist interaction sites often involves providing non-native prey items in unnatural quantities that affects the condition of fed animals 6,9. Despite the large-scale changes to diet, rate of consumption, and overall feeding ecology of marine wildlife that results from provisioning at tourist interaction sites, few of these features have been investigated 4,10,11 .
Abstract Ecotourism opportunities in the marine environment often rely heavily on provisioning to ensure the viewing of cryptic species by the public. However, intentional feeding of wildlife can impact numerous aspects of an animals’ behavior and ecology. Southern stingrays (Hypanus americana) provisioned at Stingray City Sandbar (SCS) in Grand Cayman have altered diel activity patterns and decreased measures of health. This study looked at seasonal changes in stable isotope (SI) and fatty acid (FA) profiles of provisioned stingrays at SCS. Plasma δ15N was higher in male stingrays (11.86 ± 1.71‰) compared to females (10.70 ± 1.71‰). Lower values for δ15N in males and females were measured in October during low tourist season, suggesting stingrays may be forced to rely on native prey items to supplement the decreased amount of provisioned squid available during this time. Plasma FA profiles were significantly different between sexes and across sampling time points, with FAs 22:6n3, 16:0, 20:5n3, 18:1n3C, 18:0 and 18:1n9T contributing to dissimilarity scores between groups. Dietary FAs primarily contributed to differences between males and females lending further evidence to differences in foraging patterns at SCS, likely due to intraspecific competition. Further, canonical analysis of principal coordinates (CAP) analysis of FA profiles suggest similar diets during peak tourist season and differences in diet between males and females during the low season. This study demonstrates alterations in feeding ecology in stingrays at SCS which is of critical importance for effective management of the SCS aggregation.
The new species is compared both with other Dasyatis species of the southwestern Atlantic and with similarly shaped species of Dasyatis from other areas of the world. The holotype was collected in Maraj Bay; near Colares Island, district of Colares, Bel m, Par State, Brazil. It differs from known Dasyatis species by the combination of the following characters: a diamond-shaped (rhomboid) disc; an elongate snout (preorbital distance ranges from 35.7 to 37.7 % in disc width); a dark, well defined band or dark blotches outlining the lower lips; a row of small tubercles along midline of disc from shoulder region to base of tail, presenting a widespread and random arrangement; posterior margins of pectoral fins uniformly rounded; triangular-shaped pelvic fins with posterior margin almost straight or slightly sinuous and tips exceeding the limits of the posterior margin of disc; dorsal caudal keel absent in the holotype, but vestigial in both paratypes.
Rhynchobatus mononoke sp. nov. (Rhinopristiformes: Rhinidae) is described from mature male and female specimens from southern Japan. A juvenile specimen, newly born from a captive individual collected from Kagoshima, is also referenced (non-type). The new species can be distinguished from congeners by a combination of its obtusely wedge-shaped snout, bluntly rounded dorsal fins, first dorsal fin originating about level with the pelvic-fin origin, and the outer fold on the spiracle posterior margin more pronounced than the inner fold. Distinctive coloration of the new species included a black blotch, followed by a single white spot (rarely absent) posterodorsally on the middle of the pectoral disc, and a large black blotch covering the anterior half of the undersurface of snout. Distinct white spots distally on the pectoral disc to the middorsal area were absent. Most previous records of species of Rhynchobatus in Japanese waters were reidentified as Rhynchobatus australiae, except for the records from the northern East China Sea. Rhynchobatus mononoke appears to be endemic to southern Japan.
Results of the 2017 IUCN Regional Red List Workshop for Species of the Patagonian Sea: CHONDRICHTHYANS, with 35 species of rays, skates and sharks listed: Amblyraja doellojuradoi; Atlantoraja castelnaui; Atlantoraja cyclophora; Atlantoraja platana; Bathyraja albomaculata; Bathyraja brachyurops; Bathyraja cousseauae; Bathyraja griseocauda; Bathyraja macloviana; Bathyraja scaphiops; Callorhinchus callorynchus; Carcharhinus brachyurus; Carcharias taurus; Dipturus trachyderma; Discopyge tschudii; Galeorhinus galeus; Gymnura altavela; Lamna nasus; Mustelus fasciatus; Mustelus schmitti; Myliobatis goodei; Notorynchus cepedianus; Psammobatis bergi; Pseudobatos horkelii; Rioraja agassizii; Schroederichthys bivius; Squalus acanthias; Squalus mitsukurii; Squatina argentina; Squatina Guggenheim; Sympterygia acuta; Sympterygia bonapartii; Tetronarce puelcha; Zapteryx brevirostris; Zearaja chilensis.
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