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L Schnetz, J Kriwet, C Pfaff
The first virtual reconstruction of the skeletal labyrinth of the porbeagle shark Lamna nasus and the shortfin mako shark Isurus oxyrinchus is presented here using high-resolution micro-computed tomography. The results, in comparison with previously published information, suggest relationships between skeletal labyrinth morphology and locomotion mode in chondrichthyans, but also show that further studies are required to establish such connections. Nevertheless, this study adds to the knowledge of the skeletal labyrinth morphology in two apex elasmobranch species...
November 22, 2016: Journal of Fish Biology
Yan Zeng, Zhongze Wu, Chunguang Zhang, Zhibin Meng, Zhigang Jiang, Jie Zhang
The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) has been counted on for conserving threatened marine fish since it regulates the commercial international trade of these species. Implementation of the international treaty for Mantas included on CITES Appendix II is challenging due to insufficient information on species identification and markets management. To fill the gap in such aspects, we identified five species of Mobulid rays (Mobula spps. and Manta spp) by using COI and NADH2 mtDNA markers in dried ray gill rakers from Chinese markets, namely, Mobula japonica (representing 54...
November 23, 2016: Scientific Reports
J R Ellis, S R McCully Phillips, F Poisson
There is a need to better understand the survivorship of discarded fishes, both for commercial stocks and species of conservation concern. Within European waters, the landing obligations that are currently being phased in as part of the European Union's reformed common fisheries policy means that an increasing number of fish stocks, with certain exceptions, should not be discarded unless it can be demonstrated that there is a high probability of survival. This study reviews the various approaches that have been used to examine the discard survival of elasmobranchs, both in terms of at-vessel mortality (AVM) and post-release mortality (PRM), with relevant findings summarized for both the main types of fishing gear used and by taxonomic group...
November 18, 2016: Journal of Fish Biology
M N McMillan, C Izzo, B Wade, B M Gillanders
Quantifying the elemental composition of elasmobranch calcified cartilage (hard parts) has the potential to answer a range of ecological and biological questions, at both the individual and population level. Few studies, however, have employed elemental analyses of elasmobranch hard parts. This paper provides an overview of the range of applications of elemental analysis in elasmobranchs, discussing the assumptions and potential limitations in cartilaginous fishes. It also reviews the available information on biotic and abiotic factors influencing patterns of elemental incorporation into hard parts of elasmobranchs and provides some comparative elemental assays and mapping in an attempt to fill knowledge gaps...
November 13, 2016: Journal of Fish Biology
Susan M Dippenaar
The genus Schistobrachia Kabata, 1964 (Lernaeopodidae: Siphonostomatoida) currently accommodates five species of which two infect holocephalans and three utilize elasmobranchs. Kensley & Grindley (1973) reported three females from "Dipturus batis" (Linnaeus, 1758) collected in Table Bay, South Africa, which they assigned to S. ramosa (Krøyer, 1863), a species previously known only from the North Atlantic. Re-examination of these specimens (labelled Charopinus ramosus Krøyer, 1863 and deposited in the Iziko South African Museum) and additional Schistobrachia material newly collected from the gills of various Rajiformes off the South African west and south coasts, showed that Kensley & Grindley's (1973) earlier record of S...
October 11, 2016: Zootaxa
Geoffrey A Boxshall
A new species of the cyclopoid copepod genus Ergasilus von Nordmann, 1832 is described based on material collected from the gills of an elasmobranch, Himantura oxyrhyncha (Sauvage, 1878), collected in the Java Sea off the coast of West Kalimantan, Indonesia. To justify the establishment of the new species, Ergasilus kimi sp. nov., detailed comparisons are made with the 28 congeneric species that share the combination of a 3-segmented leg 1 endopod and the presence of 2 setae on the free exopodal segment of leg 5...
October 11, 2016: Zootaxa
Chris M Wood, Marina Giacomin
Nitrogen (N) appears to be a limiting dietary resource for elasmobranchs, required not only for protein growth but also for urea-based osmoregulation. Building on recent evidence that the toxicant ammonia can be taken up actively at the gills of the shark and made into the valuable osmolyte urea, we demonstrate that the uptake exhibits classic Michaelis-Menten saturation kinetics with an affinity constant (Km) of 379 µmol l(-1), resulting in net N retention at environmentally realistic ammonia concentrations (100-400 µmol l(-1)) and net N loss through stimulated urea-N excretion at higher levels...
October 15, 2016: Journal of Experimental Biology
Andrea J Morash, Sara R C Mackellar, Louise Tunnah, David A Barnett, Kilian M Stehfest, Jayson M Semmens, Suzanne Currie
Estuarine habitats are frequently used as nurseries by elasmobranch species for their protection and abundant resources; however, global climate change is increasing the frequency and severity of environmental challenges in these estuaries that may negatively affect elasmobranch physiology. Hyposmotic events are particularly challenging for marine sharks that osmoconform, and species-specific tolerances are not well known. Therefore, we sought to determine the effects of an acute (48 h) ecologically relevant hyposmotic event (25...
2016: Conservation Physiology
K B Burgess, M B Bennett
Ethanol storage and lipid and urea extraction had no effect on bluespotted maskray Neotrygon kuhlii muscle δ(13) C values whereas urea-removal and ethanol storage increased δ(15) N values. Results presented here show a significant δ(15) N increase post-urea removal and provide additional support for this approach in future elasmobranch stable-isotope analysis (SIA) studies. Further experimental work on other elasmobranch species is needed to assess extraction and preservation effects on stable-isotope (SI) values...
October 12, 2016: Journal of Fish Biology
J R Ovenden, G M Leigh, D C Blower, A T Jones, A Moore, C Bustamante, R C Buckworth, M B Bennett, C L Dudgeon
Sustainable exploitation of fisheries populations is challenging to achieve when the size of the population prior to exploitation and the actual numbers removed over time and across fishing zones are not clearly known. Quantitative fisheries' modeling is able to address this problem, but accurate and reliable model outcomes depend on high quality input data. Much of this information is obtained through the operation of the fishery under consideration, but while this seems appropriate, biases may occur. For example, poorly quantified changes in fishing methods that increase catch rates can erroneously suggest that the overall population size is increasing...
October 11, 2016: Journal of Fish Biology
Julie Larsen, Peter Bushnell, John Steffensen, Morten Pedersen, Klaus Qvortrup, Richard Brill
We assessed the functional properties in atrial and ventricular myocardium (using isolated cardiac strips) of smooth dogfish (Mustelus canis), clearnose skate (Raja eglanteria), and sandbar shark (Carcharhinus plumbeus) by blocking Ca(2+) release from the sarcoplasmic reticulum (SR) with ryanodine and thapsigargin and measuring the resultant changes in contraction-relaxation parameters and the force-frequency relationship at 20 °C and 30 °C. We also examined ultrastructural differences with electron microscopy...
September 29, 2016: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
Georgina K Cox, Richard W Brill, Kaitlin A Bonaro, Anthony P Farrell
The coronary circulation first appeared in the chordate lineage in cartilaginous fishes where, as in birds and mammals but unlike most teleost fishes, it supplies arterial blood to the entire myocardium. Despite the pivotal position of elasmobranch fishes in the evolution of the coronary circulation, the determinants of coronary blood flow have never been investigated in this group. Elasmobranch fishes are of special interest because of the morphological arrangement of their cardiomyocytes. Unlike teleosts, the majority of the ventricular myocardium in elasmobranch fishes is distant to the venous blood returning to the heart (i...
September 27, 2016: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
Jayne M Gardiner, Jelle Atema, Robert E Hueter, Philip J Motta
The ability of predators to modulate prey capture in response to the size, location, and behavior of prey is critical to successful feeding on a variety of prey types. Modulating in response to changes in sensory information may be critical to successful foraging in a variety of environments. Three shark species with different feeding morphologies and behaviors were filmed using high-speed videography while capturing live prey: the ram-feeding blacktip shark, the ram-biting bonnethead, and the suction-feeding nurse shark...
August 25, 2016: Zoology: Analysis of Complex Systems, ZACS
B Finucci, C Bustamante, E G Jones, M R Dunn
The reproductive biology and diet of prickly dogfish Oxynotus bruniensis, a deep-sea elasmobranch, endemic to the outer continental and insular shelves of southern Australia and New Zealand, and caught as by-catch in demersal fisheries, are described from specimens caught in New Zealand waters. A total of 53 specimens were obtained from research surveys and commercial fisheries, including juveniles and adults ranging in size from 33·5 to 75·6 cm total length (LT ). Estimated size-at-maturity was 54·7 cm LT in males and 64·0 cm LT in females...
September 8, 2016: Journal of Fish Biology
A T Fields, K A Feldheim, J Gelsleichter, C Pfoertner, D D Chapman
Population structure and lineage diversification within a small, non-dispersive hammerhead shark species, the bonnethead shark Sphyrna tiburo, was assessed. Sphyrna tiburo is currently described as one continuously distributed species along the Atlantic continental margins of North, Central and South America, but recent genetic analysis of an insular population (Trinidad) suggests the possibility of cryptic speciation. To address this issue S. tiburo were sampled at six sites along c. 6200 km of continuous, continental coastline and from one island location (Grand Bahama) across a discontinuity in their distribution (the Straits of Florida), in order to test if they constitute a single lineage over this distribution...
September 7, 2016: Journal of Fish Biology
Julia Wiens, Ryan Ho, Dinesh Fernando, Ayush Kumar, Peter C Loewen, Ann Karen C Brassinga, W Gary Anderson
We report here a genome sequence for Rhodococcus sp. isolate UM008 isolated from the renal/interrenal tissue of the winter skate Leucoraja ocellata Genome sequence analysis suggests that Rhodococcus bacteria may act in a novel mutualistic relationship with their elasmobranch host, serving as biocatalysts in the steroidogenic pathway of 1α-hydroxycorticosterone.
2016: Genome Announcements
Ronald Seidel, Kady Lyons, Michael Blumer, Paul Zaslansky, Peter Fratzl, James C Weaver, Mason N Dean
The endoskeleton of elasmobranchs (sharks and rays) is comprised largely of unmineralized cartilage, differing fundamentally from the bony skeletons of other vertebrates. Elasmobranch skeletons are further distinguished by a tessellated surface mineralization, a layer of minute, polygonal, mineralized tiles called tesserae. This 'tessellation' has defined the elasmobranch group for more than 400 million years, yet the limited data on development and ultrastructure of elasmobranch skeletons (e.g. how tesserae change in shape and mineral density with age) have restricted our abilities to develop hypotheses for tessellated cartilage growth...
November 2016: Journal of Anatomy
A T Oliveira, M L G Araújo, J Pantoja-Lima, P H R Aride, M Tavares-Dias, R P Brinn, J L Marcon
Intraerythrocytic parasites are frequently found in fish, including elasmobranchs. The Amazonian rivers present well defined annual hydrological cycles that results in drastic modifications of the environmental conditions with deep implications in the life cycle of the whole associated biota in those fluvial systems. The freshwater stingray Potamotrygon wallacei (stingray cururu) is a new species restricted to the Middle Rio Negro basin and it is subject to strong alterations in their natural habitats (igapós) a result of the constant variations in the water level of Rio Negro...
August 15, 2016: Brazilian Journal of Biology, Revista Brasleira de Biologia
Cat A Gordon, Ali R Hood, Jim R Ellis
Updated descriptions and measurements for the eggcases of 10 rajiform and three scyliorhinid species occurring in the shelf seas around the British Isles are given, based on museum material, specimens collected during the 'Great Eggcase Hunt' (a Shark Trust recording project), and specimens obtained from fishery surveys. Quantitative data are given for Amblyraja radiata (n = 94), Dipturus batis (n = 24), D. cf. intermedia (n = 33), Leucoraja naevus (n = 94), Raja brachyura (n = 53), R. clavata (n = 52), R. microocellata (n = 57), R...
2016: Zootaxa
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