Relevant bibliographies by topics / Sawsharks

Academic literature on the topic 'Sawsharks'

Author: Grafiati
Published: 10 December 2022
Last updated: 29 January 2023

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Journal articles on the topic "Sawsharks"

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Raoult, V., V. Peddemors, K. Rowling, and J. E. Williamson. "Spatiotemporal distributions of two sympatric sawsharks (Pristiophorus cirratus and P. nudipinnis) in south-eastern Australian waters." Marine and Freshwater Research 71, no. 10 (2020): 1342. http://dx.doi.org/10.1071/mf19277.

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Sawsharks are one of the least well-known groups of sharks globally, yet they are caught in large numbers in south-eastern Australia. In this study we assessed spatiotemporal patterns of distribution of two co-occurring species of sawsharks, namely the common sawshark (Pristiophorus cirratus) and the southern sawshark (Pristiophorus nudipinnis), to guide future research in this area. To identify where the animals may occur in greater numbers, this study used the major commercial fishery datasets in the region, containing nearly 180000 catch records from 1990 to 2017. Several general patterns were evident. Sawsharks occurred at shallower and deeper depths than previously thought, and their geographical range was larger than documented in previous studies. Depth distributions of both species overlapped, but P. cirratus appeared more common in deeper water (at depths up to 500m), with peak common sawshark catch rates at ~400m. Seasonal standardised catch patterns across fishing methods suggested that migrations from deeper to shallower waters may occur in the Australasian autumn and winter. The greatest concentration of sawsharks, inferred by standardised catch rates, occurred to the east and west of Bass Strait between Tasmania and mainland Australia. Although standardised catch rates of sawsharks declined in gill-net fisheries by ~30%, primarily in the Bass Strait and Tasmania, sawsharks appear to be caught at consistent rates since the 1990s, inferring a possible resilience of these sharks to current levels of fishing pressure.
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2

Raoult, Vincent, Troy F. Gaston, and Jane E. Williamson. "Not all sawsharks are equal: species of co-existing sawsharks show plasticity in trophic consumption both within and between species." Canadian Journal of Fisheries and Aquatic Sciences 72, no. 11 (November 2015): 1769–75. http://dx.doi.org/10.1139/cjfas-2015-0307.

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Despite the global distribution of sawsharks, little is known about their diets or their role in the marine biosphere. As species in higher trophic positions are generally considered to be more at risk to perturbations such as fishing, understanding their role in the food chain will enable better conservation and management strategies for these species. Two sawshark species (Pristiophorus cirratus, Pristiophorus nudipinnis) co-occur in waters off east Tasmania, Australia. This study determined the trophic positions of these sawsharks and whether they avoided competing with each other through resource partitioning. Isotopic analysis of muscle tissue revealed that P. cirratus and P. nudipinnis had significantly different trophic levels, with P. cirratus likely to have a diet of primary consumers and P. nudipinnis likely to have a piscivorous diet. Owing to their different isotopic signatures, it is also likely that the sawshark rostrum has multiple functions. Both species shifted to higher trophic levels during ontogeny. Maternal isotopic signatures were detectable in P. cirratus juveniles.
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Nevatte, Ryan J., and Jane E. Williamson. "The Sawshark Redemption: Current knowledge and future directions for sawsharks (Pristiophoridae)." Fish and Fisheries 21, no. 6 (September 14, 2020): 1213–37. http://dx.doi.org/10.1111/faf.12500.

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4

Nevatte, Ryan J., Jane E. Williamson, Barbara E. Wueringer, and Michael R. Gillings. "Contrasting patterns of population structure in commercially fished sawsharks from southern Australian waters." Reviews in Fish Biology and Fisheries 31, no. 2 (February 17, 2021): 359–79. http://dx.doi.org/10.1007/s11160-021-09640-4.

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5

Nevatte, Ryan J., Barbara E. Wueringer, Michael R. Gillings, and Jane E. Williamson. "Genetic and historical evidence of common sawsharks Pristiophorus cirratus in the waters of southern Queensland." Journal of Fish Biology 95, no. 5 (September 9, 2019): 1342–45. http://dx.doi.org/10.1111/jfb.14122.

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6

Burke, Patrick J., Vincent Raoult, Lisa J. Natanson, Timothy D. Murphy, Victor Peddemors, and Jane E. Williamson. "Struggling with age: Common sawsharks (Pristiophorus cirratus) defy age determination using a range of traditional methods." Fisheries Research 231 (November 2020): 105706. http://dx.doi.org/10.1016/j.fishres.2020.105706.

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7

Welten, Monique, Moya Meredith Smith, Charlie Underwood, and Zerina Johanson. "Evolutionary origins and development of saw-teeth on the sawfish and sawshark rostrum (Elasmobranchii; Chondrichthyes)." Royal Society Open Science 2, no. 9 (September 2015): 150189. http://dx.doi.org/10.1098/rsos.150189.

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A well-known characteristic of chondrichthyans (e.g. sharks, rays) is their covering of external skin denticles (placoid scales), but less well understood is the wide morphological diversity that these skin denticles can show. Some of the more unusual of these are the tooth-like structures associated with the elongate cartilaginous rostrum ‘saw’ in three chondrichthyan groups: Pristiophoridae (sawsharks; Selachii), Pristidae (sawfish; Batoidea) and the fossil Sclerorhynchoidea (Batoidea). Comparative topographic and developmental studies of the ‘saw-teeth’ were undertaken in adults and embryos of these groups, by means of three-dimensional-rendered volumes from X-ray computed tomography. This provided data on development and relative arrangement in embryos, with regenerative replacement in adults. Saw-teeth are morphologically similar on the rostra of the Pristiophoridae and the Sclerorhynchoidea, with the same replacement modes, despite the lack of a close phylogenetic relationship. In both, tooth-like structures develop under the skin of the embryos, aligned with the rostrum surface, before rotating into lateral position and then attaching through a pedicel to the rostrum cartilage. As well, saw-teeth are replaced and added to as space becomes available. By contrast, saw-teeth in Pristidae insert into sockets in the rostrum cartilage, growing continuously and are not replaced. Despite superficial similarity to oral tooth developmental organization, saw-tooth spatial initiation arrangement is associated with rostrum growth. Replacement is space-dependent and more comparable to that of dermal skin denticles. We suggest these saw-teeth represent modified dermal denticles and lack the ‘many-for-one’ replacement characteristic of elasmobranch oral dentitions.
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Weigmann, Simon, Ofer Gon, Ruth H. Leeney, Ellen Barrowclift, Per Berggren, Narriman Jiddawi, and Andrew J. Temple. "Revision of the sixgill sawsharks, genus Pliotrema (Chondrichthyes, Pristiophoriformes), with descriptions of two new species and a redescription of P. warreni Regan." PLOS ONE 15, no. 3 (March 18, 2020): e0228791. http://dx.doi.org/10.1371/journal.pone.0228791.

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9

Smith, Moya Meredith, Alex Riley, Gareth J. Fraser, Charlie Underwood, Monique Welten, Jürgen Kriwet, Cathrin Pfaff, and Zerina Johanson. "Early development of rostrum saw-teeth in a fossil ray tests classical theories of the evolution of vertebrate dentitions." Proceedings of the Royal Society B: Biological Sciences 282, no. 1816 (October 7, 2015): 20151628. http://dx.doi.org/10.1098/rspb.2015.1628.

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In classical theory, teeth of vertebrate dentitions evolved from co-option of external skin denticles into the oral cavity. This hypothesis predicts that ordered tooth arrangement and regulated replacement in the oral dentition were also derived from skin denticles. The fossil batoid ray Schizorhiza stromeri (Chondrichthyes; Cretaceous) provides a test of this theory. Schizorhiza preserves an extended cartilaginous rostrum with closely spaced, alternating saw-teeth, different from sawfish and sawsharks today. Multiple replacement teeth reveal unique new data from micro-CT scanning, showing how the ‘cone-in-cone’ series of ordered saw-teeth sets arrange themselves developmentally, to become enclosed by the roots of pre-existing saw-teeth. At the rostrum tip, newly developing saw-teeth are present, as mineralized crown tips within a vascular, cartilaginous furrow; these reorient via two 90° rotations then relocate laterally between previously formed roots. Saw-tooth replacement slows mid-rostrum where fewer saw-teeth are regenerated. These exceptional developmental data reveal regulated order for serial self-renewal, maintaining the saw edge with ever-increasing saw-tooth size. This mimics tooth replacement in chondrichthyans, but differs in the crown reorientation and their enclosure directly between roots of predecessor saw-teeth. Schizorhiza saw-tooth development is decoupled from the jaw teeth and their replacement, dependent on a dental lamina. This highly specialized rostral saw, derived from diversification of skin denticles, is distinct from the dentition and demonstrates the potential developmental plasticity of skin denticles.
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Raoult, V., V. Peddemors, and J. E. Williamson. "Biology of angel sharks (Squatina sp.) and sawsharks (Pristiophorus sp.) caught in south-eastern Australian trawl fisheries and the New South Wales shark-meshing (bather-protection) program." Marine and Freshwater Research 68, no. 2 (2017): 207. http://dx.doi.org/10.1071/mf15369.

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Two species of angel shark (Squatina australis, S. albipunctata) and two species of sawshark (Pristiophorus nudipinnis, P. cirratus) are frequently caught in south-eastern Australia. Little is known of the biology of these elasmobranchs, despite being caught as secondary target species in large numbers. The present study collected morphometric and reproductive data from sharks caught in shark-control nets, commercial fishing trawlers and research trawlers in south-eastern Australia. All four species had female-biased sexual size dimorphism, but growth curves between sexes did not differ. Male S. australis individuals were fully mature at ~800-mm total length, male P. nudipinnis at ~900mm, and male P. cirratus at ~800mm. Anterior pectoral margins could be used to determine total length in all species. No morphometric measurement could reliably separate Squatina spp. or Pristiophorus spp., although S. albipunctata over 1000-mm total length had larger eyes than did S. australis.
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Dissertations / Theses on the topic "Sawsharks"

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Foor, Brandon. "The biology and macroparasites of the sixgill sawshark Pliotrema warreni." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/25303.

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Thirty-two specimens of the sixgill sawshark, Pliotrema warreni, were trawled near Bird Island in Algoa Bay on the Eastern coast of South Africa in April and May 2015. The specimens were examined for anatomical proportions, reproductive characteristics, diet, and parasite assemblages. Several external measurements were collected including mass, total length, standard length, girth, rostrum length, interoccular to pre-caudal length, first dorsal origin to second dorsal origin, first dorsal origin to pre-caudal origin, and mouth width. The equation for mass (g) vs. total length (mm) was ln(Mass)=0.2997*ln(TL)+2.0383 for females and ln(Mass)=0.3321*ln(TL)+1.941 for males. 1st Dorsal to 2nd dorsal origin length (DD) to total length equations for females and males were DD=0.2451*TL-26.677 and DD=0.2598*TL-34.535, respectively. Mean lengths and masses were 11.5% greater and 50.3% heavier in females than males, respectively. Females were on average, 994 mm (759 mm – 1283 mm) in length while males were 891.8 mm (763 mm – 1015 mm). Average mass for females was 1702.5 g (602.5 g – 3478.5 g) whereas males it was 1132.6 g (687 g – 1593.5 g). Based on these data both sexes display isometric growth. Males were determined to reach sexually maturity around 850 mm which is similar to that reported by Ebert et al., (2013) around 830 mm. Females were found to reach sexual maturity at 1000 mm which is 100 mm smaller than what is reported by Ebert et al., (2013). Stomach mass increased with total mass and total length regardless of sex (female R² = 0.507; male R² = 0.213 for length and female R² = 0.6123; male R² = 0996 for mass). Females consumed larger prey items in terms of mass and length as well as a higher quantity of prey than males presumably because they are the larger sex and have an increased need for nourishment to provide for pregnancy. Prey items were redeye round herring, Etrumeus whiteheadi (64.96% of the diet), a benthic shrimp species not identified (7.69%), and Cape horse mackerel, Trachurus trachurus capensis (0.85%). Despite strict adherence to the guidelines for age determination for elasmobranchs provided in the literature, the conventional method used which involved extensive cleaning of the vertebral centra with an array of chemicals, setting and cutting in an epoxy resin, and staining for microscopy, did not yield readable results which could be used to determine the ages of these sharks. The highest abundance of parasites were found in the stomachs. Three specimens of a cymothoid isopod was found externally. Two specimens of Ascaris sp. nematode were found in the visceral cavity. The remaining 18 parasites consisted of three Neoechinorhynchidae sp. of acanthocephalan and 15 Proleptus obtusus nematodes all of which were found inside the stomachs. Given the results of the parasite survey, males and females do not have the same parasites as females have four different species while males only have one. More collections from other areas and times of year are necessary to obtain a better description of the species.
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Books on the topic "Sawsharks"

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Common Sawsharks (Sharks Set II). Checkerboard Books, 2005.

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Book chapters on the topic "Sawsharks"

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"SAWSHARKS." In A Pocket Guide to Sharks of the World, 94. Princeton University Press, 2021. http://dx.doi.org/10.2307/j.ctv1cmsmwn.13.

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"SAWSHARKS Pristiophoriformes." In A Pocket Guide to Sharks of the World, 94. Princeton University Press, 2021. http://dx.doi.org/10.1515/9780691218755-011.

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"Order Pristiophoriformes: sawsharks." In Sharks of the World, 220–26. Princeton University Press, 2021. http://dx.doi.org/10.1515/9780691210872-012.

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