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Michael L Berumen - One of the best experts on this subject based on the ideXlab platform.
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fish market surveys indicate unsustainable Elasmobranch fisheries in the saudi arabian red sea
Fisheries Research, 2015Co-Authors: Julia L Y Spaet, Michael L BerumenAbstract:a b s t r a c t Elasmobranch populations worldwide are severely threatened due to overexploited and unregulated fisheries. Despite the fact that sharks and rays are captured in fisheries operating along the Red Sea coast of the Kingdom of Saudi Arabia (KSA), information on any aspects of these fisheries are very limited. Here we document the structure, composition and biological characteristics of eastern Red Sea elas- mobranch fisheries based on genetic identification and market survey data over an intensive two-year sampling period at the biggest Red Sea fish market in the KSA (Jeddah). Market surveys conducted two times per month between 2011 and 2013 revealed that 24 previously confirmed Elasmobranch species for the Red Sea were landed by fishers and offered for sale. Genetic identification revealed two poten- tially undescribed guitarfish species as well as four batoid species not formerly reported from the Red Sea. Five coastal carcharhinid species dominated the landings—Carcharhinus sorrah, C. amblyrhynchos, C. falciformis, C. limbatus, Rhizoprionodon acutus, together comprising 73% numerically of the total catch. Tar- geted shark fisheries reportedly exist in shark nursery areas. Most Elasmobranchs outside of these areas were reportedly landed as bycatch. Most strikingly, the large majority of landed Elasmobranchs were immature males or females below their reported size of sexual maturity, which suggests potential for both growth and recruitment overfishing and emphasizes the urgent need to implement region-specific management and conservation strategies to avoid the loss of these critical predators. © 2014 Published by Elsevier B.V.
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a review of Elasmobranch research in the red sea
Journal of Fish Biology, 2012Co-Authors: Julia L Y Spaet, Simon R Thorrold, Michael L BerumenAbstract:Given the global concern about the status of Elasmobranch fishes, the paucity of information on Elasmobranchs in the Red Sea is worrisome. Management of Elasmobranchs in areas other than the Red Sea has been helped by research on population ecology, reproductive biology and resource partitioning, subjects that are virtually absent in the Red Sea Elasmobranch literature. This review provides the first comprehensive summary of Elasmobranch biology in the Red Sea with the aim of facilitating research in a region that remains remarkably under-studied.
Holly A Shiels - One of the best experts on this subject based on the ideXlab platform.
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ocean warming impairs the predator avoidance behaviour of Elasmobranch embryos
Conservation Physiology, 2021Co-Authors: Daniel M Ripley, Sara De Giorgio, Kirstin Gaffney, Lowri Thomas, Holly A ShielsAbstract:Embryogenesis is a vulnerable stage in Elasmobranch development due in part to high predation mortality. Embryonic Elasmobranchs respond to potential predators by displaying a freezing behaviour, characterized by the cessation of pharyngeal respiration followed immediately by coiling of the tail around the body. We hypothesized that the duration of this freeze response is limited by the embryo's requirement for oxygen. Here, Scyliorhinus canicula embryos were incubated at either 15°C or 20°C during embryogenesis and tested for the duration of, and metabolic consequence of, the freeze response at their respective incubation temperature. Freeze response duration was negatively impacted by routine metabolic rate; embryos at 20°C had 7-fold shorter freeze duration than those at 15°C, potentially increasing their susceptibility to predation. These data demonstrate the capacity for climate change stressors to affect animal behaviour and suggest that this may occur by eliciting changes in the organism's metabolism. We suggest altered predator avoidance behaviour is a new factor to consider when assessing the impact of climate change on the conservation and management of oviparous Elasmobranch species.
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ocean warming and hypoxia affect embryonic growth fitness and survival of small spotted catsharks scyliorhinus canicula
Journal of Fish Biology, 2020Co-Authors: Syafiq M Musa, Daniel M Ripley, Timo Moritz, Holly A ShielsAbstract:Elasmobranchs are key to a healthy marine ecosystem but are under threat from human activities, such as destructive fisheries and shark finning. Embryos of oviparous Elasmobranchs may be further challenged during development by rising temperatures and falling dissolved oxygen concentrations in their intertidal environment. However, the impact of climate change on survival and growth of oviparous Elasmobranchs is still poorly understood. Here, we investigate the effects of temperature and hypoxia on the growth and survival of small-spotted catshark (Scyliorhinus canicula) embryos by incubating eggs in normoxia 15°C, normoxia 20°C, hypoxia 15°C, or hypoxia 20°C. Incubation under the elevated temperature increased the embryonic growth rate, yolk consumption rate and Fulton's condition factor at hatching, whilst decreasing the total length and body mass of newly hatched sharks. Under low oxygen conditions (50% air saturation) the survival rate of S. canicula embryos dropped significantly and the temperature-induced increase in Fulton's condition factor was reversed. Together, these data demonstrate both the individual and compound effects of elevated temperature and hypoxia on the survival and growth during early ontogeny of a ubiquitous, coastal Elasmobranch, S. canicula.
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oviparous Elasmobranch development inside the egg case in 7 key stages
PLOS ONE, 2018Co-Authors: Syafiq M Musa, Molly V Czachur, Holly A ShielsAbstract:Embryological stages of oviparous Elasmobranch during development can be difficult to identify, requiring magnification and/or fixation of an anaesthetized embryo. These restrictions are poorly suited for monitoring the development of living Elasmobranchs inside their egg cases. There are two major aims of this study. The first was to observe Elasmobranch embryonic development non-invasively and produce a non-invasive developmental key for identifying the life stages for an Elasmobranch inside the egg case. To this end, 7 key developmental stages were identified for the greater spotted catshark, Scyliorhinus stellaris, and are provided here with diagrams from multiple perspectives to demonstrate the key features of each stage. The physiological and ecological relevance of each stage are discussed in terms of structure and function for embryonic survival in the harsh intertidal zone. Also discussed is the importance of the egg case membrane and the protective embryonic jelly. The second aim of the study was to understand the applicability of the 7 developmental stages from S. stellaris to other oviparous Elasmobranchs. Thus, changes in embryonic body size and egg yolk volume at each stage were measured and compared with those of the closely related, lesser spotted catshark, Scyliorhinus canicula. We find nearly identical growth patterns and yolk consumption patterns in both species across the 7 developmental stages. Thus, although the 7 developmental stages have been constructed in reference to the greater spotted catshark, we suggest that it can be applied to other oviparous Elasmobranch species with only minor modification.
Syafiq M Musa - One of the best experts on this subject based on the ideXlab platform.
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ocean warming and hypoxia affect embryonic growth fitness and survival of small spotted catsharks scyliorhinus canicula
Journal of Fish Biology, 2020Co-Authors: Syafiq M Musa, Daniel M Ripley, Timo Moritz, Holly A ShielsAbstract:Elasmobranchs are key to a healthy marine ecosystem but are under threat from human activities, such as destructive fisheries and shark finning. Embryos of oviparous Elasmobranchs may be further challenged during development by rising temperatures and falling dissolved oxygen concentrations in their intertidal environment. However, the impact of climate change on survival and growth of oviparous Elasmobranchs is still poorly understood. Here, we investigate the effects of temperature and hypoxia on the growth and survival of small-spotted catshark (Scyliorhinus canicula) embryos by incubating eggs in normoxia 15°C, normoxia 20°C, hypoxia 15°C, or hypoxia 20°C. Incubation under the elevated temperature increased the embryonic growth rate, yolk consumption rate and Fulton's condition factor at hatching, whilst decreasing the total length and body mass of newly hatched sharks. Under low oxygen conditions (50% air saturation) the survival rate of S. canicula embryos dropped significantly and the temperature-induced increase in Fulton's condition factor was reversed. Together, these data demonstrate both the individual and compound effects of elevated temperature and hypoxia on the survival and growth during early ontogeny of a ubiquitous, coastal Elasmobranch, S. canicula.
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oviparous Elasmobranch development inside the egg case in 7 key stages
PLOS ONE, 2018Co-Authors: Syafiq M Musa, Molly V Czachur, Holly A ShielsAbstract:Embryological stages of oviparous Elasmobranch during development can be difficult to identify, requiring magnification and/or fixation of an anaesthetized embryo. These restrictions are poorly suited for monitoring the development of living Elasmobranchs inside their egg cases. There are two major aims of this study. The first was to observe Elasmobranch embryonic development non-invasively and produce a non-invasive developmental key for identifying the life stages for an Elasmobranch inside the egg case. To this end, 7 key developmental stages were identified for the greater spotted catshark, Scyliorhinus stellaris, and are provided here with diagrams from multiple perspectives to demonstrate the key features of each stage. The physiological and ecological relevance of each stage are discussed in terms of structure and function for embryonic survival in the harsh intertidal zone. Also discussed is the importance of the egg case membrane and the protective embryonic jelly. The second aim of the study was to understand the applicability of the 7 developmental stages from S. stellaris to other oviparous Elasmobranchs. Thus, changes in embryonic body size and egg yolk volume at each stage were measured and compared with those of the closely related, lesser spotted catshark, Scyliorhinus canicula. We find nearly identical growth patterns and yolk consumption patterns in both species across the 7 developmental stages. Thus, although the 7 developmental stages have been constructed in reference to the greater spotted catshark, we suggest that it can be applied to other oviparous Elasmobranch species with only minor modification.
Kirsten Jensen - One of the best experts on this subject based on the ideXlab platform.
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a digest of Elasmobranch tapeworms
Journal of Parasitology, 2014Co-Authors: Janine N Caira, Kirsten JensenAbstract:This review brings together decades of work on Elasmobranch tapeworms. The field has advanced significantly over the past 20 yr, with an emphasis on the discovery and description of novel taxa, and the establishment of phylogenetic frameworks for individual orders and their interrelationships. Tapeworms parasitizing Elasmobranchs represent 9 orders and include 977 species and 201 genera-over 250 species and 50 genera are new within the last 2 decades. The 9 orders are treated individually, highlighting recent assessments of phylogenetic relationships informed by molecular sequence data. All but the "Tetraphyllidea" are monophyletic. Although much remains to be learned about their interrelationships, existing phylogenetic hypotheses suggest that Elasmobranch tapeworms have played a key role in the evolution of the cestodes of essentially all other vertebrate groups. The apical organ is a defining feature (i.e., a synapomorphy) of a clade consisting of acetabulate taxa and Litobothriidea. Novel hook amino acid composition data support the independent origin of hooks in the various groups of hooked tapeworms. Cestode records exist for representatives of most of the major groups of Elasmobranchs, however skates (Rajiformes) and catsharks ("Scyliorhinidae") are particularly neglected in terms of species sampled. The majority of tapeworm species are extremely host-specific exhibiting species-specific (i.e., oioxenous) associations with their hosts. Rapid advancements in Elasmobranch taxonomy, with over 300 of the 1,200 species appearing new in the past 20 yr, signal the need for careful attention to be paid to host identifications; such identifications are best documented using a combination of specimen, photographic, and molecular data. Above the species level, many cestode taxa are restricted to host orders, families, or even genera. Documentation of these affiliations allows robust predictions to be made regarding the cestode faunas of unexplored Elasmobranchs. Trypanorhynchs are the notable exceptions. Life cycles remain poorly known. Recent applications of molecular methods to larval identifications have reinvigorated this area of research. Tapeworms are more diverse in Elasmobranchs of tropical and subtropical waters, but they occur globally not only at the poles and in deep waters, but also in freshwaters of South America and Southeast Asia. The cestode faunas of batoids are much more speciose and complex than those of sharks. The faunas of deeper water sharks are particularly depauperate. The tapeworms of Elasmobranchs and their hosts are now among the most well documented host-parasite systems in existence. This system has not yet reached its potential as a resource for investigations of basic ecological and evolutionary principles.
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a digest of Elasmobranch tapeworms
Journal of Parasitology, 2014Co-Authors: Janine N Caira, Kirsten JensenAbstract:Abstract: This review brings together decades of work on Elasmobranch tapeworms. The field has advanced significantly over the past 20 yr, with an emphasis on the discovery and description of novel taxa, and the establishment of phylogenetic frameworks for individual orders and their interrelationships. Tapeworms parasitizing Elasmobranchs represent 9 orders and include 977 species and 201 genera—over 250 species and 50 genera are new within the last 2 decades. The 9 orders are treated individually, highlighting recent assessments of phylogenetic relationships informed by molecular sequence data. All but the “Tetraphyllidea” are monophyletic. Although much remains to be learned about their interrelationships, existing phylogenetic hypotheses suggest that Elasmobranch tapeworms have played a key role in the evolution of the cestodes of essentially all other vertebrate groups. The apical organ is a defining feature (i.e., a synapomorphy) of a clade consisting of acetabulate taxa and Litobothriidea. Novel ho...
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a dna sequence based approach to the identification of shark and ray species and its implications for global Elasmobranch diversity and parasitology
Bulletin of the American Museum of Natural History, 2012Co-Authors: Gavin J P Naylor, Janine N Caira, Kirsten Jensen, K A M Rosana, William T WhiteAbstract:Abstract In an effort to provide a framework for the accurate identification of Elasmobranchs, driven in large part by the needs of parasitological studies, a comprehensive survey of DNA sequences derived from the mitochondrial NADH2 gene was conducted for Elasmobranchs collected from around the world. Analysis was based on sequences derived from 4283 specimens representing an estimated 574 (of ∼1221) species (305 sharks, 269 batoids), each represented by 1 to 176 specimens, in 157 (of 193 described) Elasmobranch genera in 56 (of 57 described) families of Elasmobranchs (only Hypnidae was not represented). A total of 1921 (44.9%) of the samples were represented by vouchers and/or images available in an online host specimen database (http://Elasmobranchs.tapewormdb.uconn.edu). A representative sequence for each of the 574 species identified in this survey, as well as an additional 11 sequences for problematic complexes, has been deposited in GenBank. Neighbor-joining analysis of the data revealed a substant...
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Elasmobranch phylogeny a mitochondrial estimate based on 595 species
2012Co-Authors: Gavin J P Naylor, Janine N Caira, Kirsten Jensen, K A M Rosana, Nicolas Straube, Clemens LaknerAbstract:Interest in Elasmobranch biodiversity and taxonomy has grown in recent years, catalyzed primarily by four influences: (1) the large number of new species that have been described over the past 30 years (e.g., Last and Stevens, 2009); (2) the recognition that many species of Elasmobranchs, several of which have not yet been formally described, may be threatened with extinction from fishing pressures and habitat destruction (Stevens et al., 2000); (3) the growing interest in DNA “barcoding” as a tool to augment taxonomic description (e.g., Ward et al., 2007); and (4) an emerging recognition of the important role that Elasmobranchs play as top predators in marine ecosystems (Heithaus et al., 2008). Increasingly, Elasmobranch workers across a wide range of fields of science, both pure and applied, are recognizing the importance of an accurate species-level taxonomy. Fisheries scientists are ever more keenly aware of the need for accurate species-level assessments of catches to manage fisheries effectively. Ecologists have become more careful to ensure that the animals to which life history attributes are ascribed constitute distinct species rather than assemblages of closely related congeners with potentially different ecological roles and life history attributes. Finally, conservation biologists are beginning to recognize how critically important it is to have an accurate understanding of species compositions based on careful taxonomy to prioritize and manage units of biodiversity for conservation (Griffiths et al., 2010; Iglesias et al., 2009; White and Kyne, 2010). CONTENTS
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an investigation of the co evolutionary relationships between onchobothriid tapeworms and their Elasmobranch hosts
International Journal for Parasitology, 2001Co-Authors: Janine N Caira, Kirsten JensenAbstract:Abstract There is general consensus that the living Elasmobranchs comprise a monophyletic taxon. There is evidence that, among tetraphyllidean tapeworms, the ∼201 hooked species (Onchobothriidae) may also comprise a monophyletic group. Determinations of host specificity are contingent upon correct specific identifications. Since 1960, over 200 new Elasmobranch species and over 100 new onchobothriid species have been described. Some confidence can be placed in host and parasite identifications of recent studies, but specific identifications provided in older literature in many cases are suspect. There is some consensus among published works on the phylogenetic relationships among Elasmobranchs. Phylogenetic relationships among onchobothriids remain largely unresolved. Elasmobranchs have been poorly sampled for onchobothriids; records exist for ∼20% of the 911 species and ∼44% of the 170 Elasmobranch genera. Onchobothriids are remarkably host specific, exhibiting essentially oioxenous specificity for their definitive hosts. Multiple onchobothriid species commonly parasitise the same host species; in some cases these are congeners, in other cases these are members of two different onchobothriid genera. There is substantial incongruence between available host and parasite phylogenies. For example, Acanthobothrium is by far the most ubiquitous onchobothriid genus, parasitising almost all orders of Elasmobranchs known to host onchobothriids, yet, there is no evidence of major clades of Acanthobothrium corresponding to postulated major subgroupings of Elasmobranchs (e.g. Galea and Squalea or sharks and rays). Potamotrygonocestus appears to be among the most basal onchobothriid groups, yet it parasitises one of the most derived Elasmobranch groups (the freshwater stingray genus Potamotrygon). It appears that congeners parasitising the same host species are not necessarily each other's closest relatives. At this point the preliminary and limited available data suggest that, at least in this system, strict host specificity is not necessarily indicative of strict co-evolution. This study was extremely limited by the lack of available robust phylogenies for onchobothriids and Elasmobranchs.
Ingo S Wehrtmann - One of the best experts on this subject based on the ideXlab platform.
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assessing the vulnerability of demersal Elasmobranchs to a data poor shrimp trawl fishery in costa rica eastern tropical pacific
Biological Conservation, 2018Co-Authors: Tayler M Clarke, Mario Espinoza, Raquel Romero Chaves, Ingo S WehrtmannAbstract:Abstract The impact of shrimp trawl fisheries on slow-growing demersal sharks, skates and rays has been widely documented. Yet, a lack of catch records and biological information has hindered improvements in Elasmobranch bycatch management, particularly in tropical regions. When information is scarce, data–poor methods can be valuable tools to guide the management and conservation of vulnerable marine taxa. Here we combined an Ecological Risk Assessment commonly used in data-deficient fisheries (Productivity Susceptibility Analysis or PSA) with a spatial analysis (Hotspot Analysis) to (i) identify which Elasmobranch species are most vulnerable to the Costa Rican shrimp trawl fishery, and (ii) locate areas and seasons with high concentrations of vulnerable Elasmobranchs. According to the results of our PSA, the scalloped hammerhead (Sphyrna lewini), prickly shark (Echinorhinus cookei), and long–tail stingray (Hypanus longus) were the most vulnerable species, while the least vulnerable species were small batoids of the Urotrygonidae family. We identified large information gaps, namely demographic parameter estimates and long–term bycatch trends. Spatial aggregations of vulnerable Elasmobranchs occurred near highly productive estuaries and coastal habitats, especially at depths of 50–100 m. Based on our findings, PSA and Hotspot analyses can be powerful tools to identify spatial areas where trawl fishing grounds overlap with the habitat of vulnerable bycatch species, and thus can be used to design spatial trawling closures that protect species at risk. We therefore conclude that our methodological approach may aid in the implementation of ecosystem–based fisheries management in data–poor situations.