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Jeanine L. Olsen - One of the best experts on this subject based on the ideXlab platform.
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multiple paternity analysis in the thornback ray Raja clavata l
Journal of Heredity, 2007Co-Authors: Malia Chevolot, Jim R. Ellis, Wytze T. Stam, A D Rijnsdorp, Jeanine L. OlsenAbstract:Skates (Rajidae) are characterized by slow growth rate, low fecundity, and late maturity and are thus considered to be vulnerable to exploitation. Although understanding mating systems and behavior are important for long-term conservation and fisheries management, this aspect of life history is poorly understood in skates. Using 5 highly polymorphic microsatellite loci, we analyzed egg clutches collected from 4 female Raja clavata captured in the wild to test for multiple paternity. Using the reconstructed multilocus genotypes method to explain the progeny genotype array, we showed that all 4 clutches were sired by a minimum of 4-6 fathers and, thus, female thornback rays are polyandrous. Whether polyandry in R. clavata is natural or a consequence of overexploitation remains uncertain. This is the first report of multiple paternity in a rajiform species and any oviparous elasmobranch.
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Population structure of the thornback ray (Raja clavata L.) in British waters
Journal of Sea Research, 2006Co-Authors: Malia Chevolot, Jim R. Ellis, Galice Hoarau, Adriaan D. Rijnsdorp, Wytze T. Stam, Jeanine L. OlsenAbstract:Prior to the 1950s, thornback ray (Raja clavata L.) was common and widely distributed in the seas of Northwest Europe. Since then, it has decreased in abundance and geographic range due to over-fishing. The sustainability of ray populations is of concern to fisheries management because their slow growth rate, late maturity and low fecundity make them susceptible to exploitation as victims of by-catch. We investigated the population genetic structure of thornback rays from 14 locations in the southern North Sea, English Channel and Irish Sea. Adults comprised
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population structure of the thornback ray Raja clavata l in british waters
Journal of Sea Research, 2006Co-Authors: Malia Chevolot, Jim R. Ellis, Galice Hoarau, Wytze T. Stam, A D Rijnsdorp, Jeanine L. OlsenAbstract:Prior to the 1950s, thornback ray (Raja clavata L.) was common and widely distributed in the seas of Northwest Europe. Since then, it has decreased in abundance and geographic range due to over-fishing. The sustainability of ray populations is of concern to fisheries management because their slow growth rate, late maturity and low fecundity make them susceptible to exploitation as victims of by-catch. We investigated the population genetic structure of thornback rays from 14 locations in the southern North Sea, English Channel and Irish Sea. Adults comprised <4% of the total sampling despite heavy sampling effort over 47 hauls; thus our results apply mainly to sexually immature individuals. Using five microsatellite loci, weak but significant population differentiation was detected with a global F-ST = 0.013 (P <0.001). Pairwise F-st was significant for 75 out of 171 comparisons. Although earlier tagging studies suggest restricted foraging distances from home areas, the absence of genetic differentiation between some distant populations suggests that a substantial fraction of individuals migrate over wide areas. Autumn/winter locations appear to have a lower level of differentiation than spring/summer, which could be due to seasonal migration. Management and conservation of thornback ray populations will be challenging as population structure appears to be dynamic in space and time. (c) 2006 Elsevier B.V. All rights reserved.
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phylogeography and population structure of thornback rays Raja clavata l rajidae
Molecular Ecology, 2006Co-Authors: Malia Chevolot, Galice Hoarau, Wytze T. Stam, A D Rijnsdorp, Jeanine L. OlsenAbstract:The phylogeography of thornback rays (Raja clavata) was assessed from European waters, using five nuclear microsatellite loci and mitochondrial cytochome b sequences. Strong regional differentiation was found between the Mediterranean basin, the Azores and the European continental shelf. Allelic and haplotype diversities were high in Portuguese populations, consistent with the existence of a refugium along the Iberian Peninsula. Unexpectedly, high diversity was also found in the English Channel/North Sea area. The lowest genetic diversity was found in the Black Sea. Populations sampled from the Mediterranean, Adriatic and Black Seas were characterized by a single mitochondrial haplotype. This haplotype was also the most ancestral and widespread outside of the Mediterranean basin except for the Azores. Populations from the Azores were dominated by a second ancestral haplotype which was shared with British populations. Results from multidimensional scaling, amova and nested clade analysis indicate that British waters are a secondary contact zone recolonized from at least two refugia - one around the Iberian Peninsula and one possibly in the Azores. Links to a potential refugium known as the Hurd Deep, between Cornwall and Brittany, are discussed. Finally, a historical demographic analysis indicates that thornback ray populations started to expand between 580 000 and 362 000 years ago, which suggests that the Last Glacial Maximum (20 000 years ago) had mainly affected the distribution of populations rather than population size.
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Phylogeography and population structure of the thornback ray (Raja clavata L.).
Molecular Ecology, 2006Co-Authors: Malia Chevolot, Galice Hoarau, Adriaan D. Rijnsdorp, Wytze T. Stam, Jeanine L. OlsenAbstract:The phylogeography of thornback rays (Raja clavata) was assessed from European waters, using five nuclear microsatellite loci and mitochondrial cytochome b sequences. Strong regional differentiation was found between the Mediterranean basin, the Azores and the European continental shelf. Allelic and haplotype diversities were high in Portuguese populations, consistent with the existence of a refugium along the Iberian Peninsula. Unexpectedly, high diversity was also found in the English Channel/North Sea area. The lowest genetic diversity was found in the Black Sea. Populations sampled from the Mediterranean, Adriatic and Black Seas were characterized by a single mitochondrial haplotype. This haplotype was also the most ancestral and widespread outside of the Mediterranean basin except for the Azores. Populations from the Azores were dominated by a second ancestral haplotype which was shared with British populations. Results from multidimensional scaling, amova and nested clade analysis indicate that British waters are a secondary contact zone recolonized from at least two refugia - one around the Iberian Peninsula and one possibly in the Azores. Links to a potential refugium known as the Hurd Deep, between Cornwall and Brittany, are discussed. Finally, a historical demographic analysis indicates that thornback ray populations started to expand between 580 000 and 362 000 years ago, which suggests that the Last Glacial Maximum (20 000 years ago) had mainly affected the distribution of populations rather than population size.
Malia Chevolot - One of the best experts on this subject based on the ideXlab platform.
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multiple paternity analysis in the thornback ray Raja clavata l
Journal of Heredity, 2007Co-Authors: Malia Chevolot, Jim R. Ellis, Wytze T. Stam, A D Rijnsdorp, Jeanine L. OlsenAbstract:Skates (Rajidae) are characterized by slow growth rate, low fecundity, and late maturity and are thus considered to be vulnerable to exploitation. Although understanding mating systems and behavior are important for long-term conservation and fisheries management, this aspect of life history is poorly understood in skates. Using 5 highly polymorphic microsatellite loci, we analyzed egg clutches collected from 4 female Raja clavata captured in the wild to test for multiple paternity. Using the reconstructed multilocus genotypes method to explain the progeny genotype array, we showed that all 4 clutches were sired by a minimum of 4-6 fathers and, thus, female thornback rays are polyandrous. Whether polyandry in R. clavata is natural or a consequence of overexploitation remains uncertain. This is the first report of multiple paternity in a rajiform species and any oviparous elasmobranch.
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Population structure of the thornback ray (Raja clavata L.) in British waters
Journal of Sea Research, 2006Co-Authors: Malia Chevolot, Jim R. Ellis, Galice Hoarau, Adriaan D. Rijnsdorp, Wytze T. Stam, Jeanine L. OlsenAbstract:Prior to the 1950s, thornback ray (Raja clavata L.) was common and widely distributed in the seas of Northwest Europe. Since then, it has decreased in abundance and geographic range due to over-fishing. The sustainability of ray populations is of concern to fisheries management because their slow growth rate, late maturity and low fecundity make them susceptible to exploitation as victims of by-catch. We investigated the population genetic structure of thornback rays from 14 locations in the southern North Sea, English Channel and Irish Sea. Adults comprised
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population structure of the thornback ray Raja clavata l in british waters
Journal of Sea Research, 2006Co-Authors: Malia Chevolot, Jim R. Ellis, Galice Hoarau, Wytze T. Stam, A D Rijnsdorp, Jeanine L. OlsenAbstract:Prior to the 1950s, thornback ray (Raja clavata L.) was common and widely distributed in the seas of Northwest Europe. Since then, it has decreased in abundance and geographic range due to over-fishing. The sustainability of ray populations is of concern to fisheries management because their slow growth rate, late maturity and low fecundity make them susceptible to exploitation as victims of by-catch. We investigated the population genetic structure of thornback rays from 14 locations in the southern North Sea, English Channel and Irish Sea. Adults comprised <4% of the total sampling despite heavy sampling effort over 47 hauls; thus our results apply mainly to sexually immature individuals. Using five microsatellite loci, weak but significant population differentiation was detected with a global F-ST = 0.013 (P <0.001). Pairwise F-st was significant for 75 out of 171 comparisons. Although earlier tagging studies suggest restricted foraging distances from home areas, the absence of genetic differentiation between some distant populations suggests that a substantial fraction of individuals migrate over wide areas. Autumn/winter locations appear to have a lower level of differentiation than spring/summer, which could be due to seasonal migration. Management and conservation of thornback ray populations will be challenging as population structure appears to be dynamic in space and time. (c) 2006 Elsevier B.V. All rights reserved.
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phylogeography and population structure of thornback rays Raja clavata l rajidae
Molecular Ecology, 2006Co-Authors: Malia Chevolot, Galice Hoarau, Wytze T. Stam, A D Rijnsdorp, Jeanine L. OlsenAbstract:The phylogeography of thornback rays (Raja clavata) was assessed from European waters, using five nuclear microsatellite loci and mitochondrial cytochome b sequences. Strong regional differentiation was found between the Mediterranean basin, the Azores and the European continental shelf. Allelic and haplotype diversities were high in Portuguese populations, consistent with the existence of a refugium along the Iberian Peninsula. Unexpectedly, high diversity was also found in the English Channel/North Sea area. The lowest genetic diversity was found in the Black Sea. Populations sampled from the Mediterranean, Adriatic and Black Seas were characterized by a single mitochondrial haplotype. This haplotype was also the most ancestral and widespread outside of the Mediterranean basin except for the Azores. Populations from the Azores were dominated by a second ancestral haplotype which was shared with British populations. Results from multidimensional scaling, amova and nested clade analysis indicate that British waters are a secondary contact zone recolonized from at least two refugia - one around the Iberian Peninsula and one possibly in the Azores. Links to a potential refugium known as the Hurd Deep, between Cornwall and Brittany, are discussed. Finally, a historical demographic analysis indicates that thornback ray populations started to expand between 580 000 and 362 000 years ago, which suggests that the Last Glacial Maximum (20 000 years ago) had mainly affected the distribution of populations rather than population size.
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Phylogeography and population structure of the thornback ray (Raja clavata L.).
Molecular Ecology, 2006Co-Authors: Malia Chevolot, Galice Hoarau, Adriaan D. Rijnsdorp, Wytze T. Stam, Jeanine L. OlsenAbstract:The phylogeography of thornback rays (Raja clavata) was assessed from European waters, using five nuclear microsatellite loci and mitochondrial cytochome b sequences. Strong regional differentiation was found between the Mediterranean basin, the Azores and the European continental shelf. Allelic and haplotype diversities were high in Portuguese populations, consistent with the existence of a refugium along the Iberian Peninsula. Unexpectedly, high diversity was also found in the English Channel/North Sea area. The lowest genetic diversity was found in the Black Sea. Populations sampled from the Mediterranean, Adriatic and Black Seas were characterized by a single mitochondrial haplotype. This haplotype was also the most ancestral and widespread outside of the Mediterranean basin except for the Azores. Populations from the Azores were dominated by a second ancestral haplotype which was shared with British populations. Results from multidimensional scaling, amova and nested clade analysis indicate that British waters are a secondary contact zone recolonized from at least two refugia - one around the Iberian Peninsula and one possibly in the Azores. Links to a potential refugium known as the Hurd Deep, between Cornwall and Brittany, are discussed. Finally, a historical demographic analysis indicates that thornback ray populations started to expand between 580 000 and 362 000 years ago, which suggests that the Last Glacial Maximum (20 000 years ago) had mainly affected the distribution of populations rather than population size.
Wytze T. Stam - One of the best experts on this subject based on the ideXlab platform.
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multiple paternity analysis in the thornback ray Raja clavata l
Journal of Heredity, 2007Co-Authors: Malia Chevolot, Jim R. Ellis, Wytze T. Stam, A D Rijnsdorp, Jeanine L. OlsenAbstract:Skates (Rajidae) are characterized by slow growth rate, low fecundity, and late maturity and are thus considered to be vulnerable to exploitation. Although understanding mating systems and behavior are important for long-term conservation and fisheries management, this aspect of life history is poorly understood in skates. Using 5 highly polymorphic microsatellite loci, we analyzed egg clutches collected from 4 female Raja clavata captured in the wild to test for multiple paternity. Using the reconstructed multilocus genotypes method to explain the progeny genotype array, we showed that all 4 clutches were sired by a minimum of 4-6 fathers and, thus, female thornback rays are polyandrous. Whether polyandry in R. clavata is natural or a consequence of overexploitation remains uncertain. This is the first report of multiple paternity in a rajiform species and any oviparous elasmobranch.
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Population structure of the thornback ray (Raja clavata L.) in British waters
Journal of Sea Research, 2006Co-Authors: Malia Chevolot, Jim R. Ellis, Galice Hoarau, Adriaan D. Rijnsdorp, Wytze T. Stam, Jeanine L. OlsenAbstract:Prior to the 1950s, thornback ray (Raja clavata L.) was common and widely distributed in the seas of Northwest Europe. Since then, it has decreased in abundance and geographic range due to over-fishing. The sustainability of ray populations is of concern to fisheries management because their slow growth rate, late maturity and low fecundity make them susceptible to exploitation as victims of by-catch. We investigated the population genetic structure of thornback rays from 14 locations in the southern North Sea, English Channel and Irish Sea. Adults comprised
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population structure of the thornback ray Raja clavata l in british waters
Journal of Sea Research, 2006Co-Authors: Malia Chevolot, Jim R. Ellis, Galice Hoarau, Wytze T. Stam, A D Rijnsdorp, Jeanine L. OlsenAbstract:Prior to the 1950s, thornback ray (Raja clavata L.) was common and widely distributed in the seas of Northwest Europe. Since then, it has decreased in abundance and geographic range due to over-fishing. The sustainability of ray populations is of concern to fisheries management because their slow growth rate, late maturity and low fecundity make them susceptible to exploitation as victims of by-catch. We investigated the population genetic structure of thornback rays from 14 locations in the southern North Sea, English Channel and Irish Sea. Adults comprised <4% of the total sampling despite heavy sampling effort over 47 hauls; thus our results apply mainly to sexually immature individuals. Using five microsatellite loci, weak but significant population differentiation was detected with a global F-ST = 0.013 (P <0.001). Pairwise F-st was significant for 75 out of 171 comparisons. Although earlier tagging studies suggest restricted foraging distances from home areas, the absence of genetic differentiation between some distant populations suggests that a substantial fraction of individuals migrate over wide areas. Autumn/winter locations appear to have a lower level of differentiation than spring/summer, which could be due to seasonal migration. Management and conservation of thornback ray populations will be challenging as population structure appears to be dynamic in space and time. (c) 2006 Elsevier B.V. All rights reserved.
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phylogeography and population structure of thornback rays Raja clavata l rajidae
Molecular Ecology, 2006Co-Authors: Malia Chevolot, Galice Hoarau, Wytze T. Stam, A D Rijnsdorp, Jeanine L. OlsenAbstract:The phylogeography of thornback rays (Raja clavata) was assessed from European waters, using five nuclear microsatellite loci and mitochondrial cytochome b sequences. Strong regional differentiation was found between the Mediterranean basin, the Azores and the European continental shelf. Allelic and haplotype diversities were high in Portuguese populations, consistent with the existence of a refugium along the Iberian Peninsula. Unexpectedly, high diversity was also found in the English Channel/North Sea area. The lowest genetic diversity was found in the Black Sea. Populations sampled from the Mediterranean, Adriatic and Black Seas were characterized by a single mitochondrial haplotype. This haplotype was also the most ancestral and widespread outside of the Mediterranean basin except for the Azores. Populations from the Azores were dominated by a second ancestral haplotype which was shared with British populations. Results from multidimensional scaling, amova and nested clade analysis indicate that British waters are a secondary contact zone recolonized from at least two refugia - one around the Iberian Peninsula and one possibly in the Azores. Links to a potential refugium known as the Hurd Deep, between Cornwall and Brittany, are discussed. Finally, a historical demographic analysis indicates that thornback ray populations started to expand between 580 000 and 362 000 years ago, which suggests that the Last Glacial Maximum (20 000 years ago) had mainly affected the distribution of populations rather than population size.
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Phylogeography and population structure of the thornback ray (Raja clavata L.).
Molecular Ecology, 2006Co-Authors: Malia Chevolot, Galice Hoarau, Adriaan D. Rijnsdorp, Wytze T. Stam, Jeanine L. OlsenAbstract:The phylogeography of thornback rays (Raja clavata) was assessed from European waters, using five nuclear microsatellite loci and mitochondrial cytochome b sequences. Strong regional differentiation was found between the Mediterranean basin, the Azores and the European continental shelf. Allelic and haplotype diversities were high in Portuguese populations, consistent with the existence of a refugium along the Iberian Peninsula. Unexpectedly, high diversity was also found in the English Channel/North Sea area. The lowest genetic diversity was found in the Black Sea. Populations sampled from the Mediterranean, Adriatic and Black Seas were characterized by a single mitochondrial haplotype. This haplotype was also the most ancestral and widespread outside of the Mediterranean basin except for the Azores. Populations from the Azores were dominated by a second ancestral haplotype which was shared with British populations. Results from multidimensional scaling, amova and nested clade analysis indicate that British waters are a secondary contact zone recolonized from at least two refugia - one around the Iberian Peninsula and one possibly in the Azores. Links to a potential refugium known as the Hurd Deep, between Cornwall and Brittany, are discussed. Finally, a historical demographic analysis indicates that thornback ray populations started to expand between 580 000 and 362 000 years ago, which suggests that the Last Glacial Maximum (20 000 years ago) had mainly affected the distribution of populations rather than population size.
Leonel Serrano Gordo - One of the best experts on this subject based on the ideXlab platform.
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Maturation, fecundity, and spawning strategy of the thornback ray, Raja clavata: do reproductive characteristics vary regionally?
Marine Biology, 2011Co-Authors: Bárbara Serra-pereira, Ivone Figueiredo, Leonel Serrano GordoAbstract:In Portuguese waters, thornback ray Raja clavata spawns mainly between May and January, although females and males in spawning condition are found throughout the year. The maturation process can be divided into three main phases by using information on gonad weight, oviducal gland and uterus width in females and on gonad weight, clasper length and sperm duct width in males. Females attain length-at-first-maturity at 784 mm and males at 676 mm, at ages of 7.5 and 5.8 years, respectively. In females larger than length-at-first-maturity, a resting stage was identified characterized by low gonadosomatic index and well-developed oviducal glands and uteri. These results along with the low proportion of adult females that are effectively reproducing per month demonstrated that the thornback ray cannot be considered a continuous spawner as described in other studies. Fecundity was determinate with about 35 eggs released per batch. During the spawning season, a total of four batch episodes occur indicating that the total fecundity was approximately 136 eggs per female. Regional differences may exist in the reproductive strategy of the species, namely on the duration of the spawning season, length-at-first-maturity, and fecundity, which can be related to a more intense fishing pressure in northern European waters.
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the development of the oviducal gland in the rajid thornback ray Raja clavata
Helgoland Marine Research, 2011Co-Authors: Barbara Serrapereira, F Afonso, Ines Farias, Pedro Joyce, Megan Ellis, Ivone Figueiredo, Leonel Serrano GordoAbstract:The reproductive processes of chondrichthyans are complex. Knowledge of the development and maturation of the oviducal gland is vital for understanding the reproductive biology of a species. This study represents the first contribution of this subject for skates. In the oviparous thornback ray, Raja clavata, oviducal gland development begins early in the developing stage with the formation of gland tubules and the distinct lamellae of each zone: club, papillary, baffle and terminal. Oviducal development is complete by the end of the developing stage when the storage and secretion of products is evident within the gland tubules of each zone. Periodic acid-Schiff and alcian blue histological staining showed that the secretory mucous cells of the club and papillary zones produce neutral and sulfated acid mucins. The last row of gland tubules of the papillary zone stains intensely for sulfated acid mucins. The baffle zone, which is responsible for the production of the egg capsule, represented 60–80% of the glandular zone of the oviducal gland. Sperm bundles were observed in the deeper recesses of the baffle zone during the maturation process, and during capsule extrusion, sperm were detected near the lumen. The terminal zone was composed of two types of gland tubules: serous (producing protein fibres) and mucous glands (producing sulfated acid mucins).
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maturation of the gonads and reproductive tracts of the thornback ray Raja clavata with comments on the development of a standardized reproductive terminology for oviparous elasmobranchs
Marine and Coastal Fisheries: Dynamics Management and Ecosystem Science, 2011Co-Authors: Barbara Serrapereira, Ivone Figueiredo, Leonel Serrano GordoAbstract:Abstract There is a need for a unified terminology to describe reproductive phase assignment across fish taxa, regardless of the reproductive strategy involved. Reproductive terminology already adopted for teleosts has been applied to oviparous elasmobranchs of both sexes. A historical review of the terminologies used by previous authors and how these correspond to the new terminology is presented. Five reproductive phases are considered: immature, developing, spawning capable (which includes an actively spawning subphase), regressing, and regenerating. By using an oviparous elasmobranch, the thornback ray Raja clavata, as an example, the different phases are described based on both macroscopic and microscopic features of the reproductive tract, including the ovaries, oviducal glands, and uterus in females and the testes, claspers, and sperm ducts in males. The regressing phase was observed in females, but the regenerating phase was not; neither of these two phases was observed in males. Records from othe...
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description of dermal denticles from the caudal region of Raja clavata and their use for the estimation of age and growth
Ices Journal of Marine Science, 2008Co-Authors: Barbara Serrapereira, Ines Farias, Ivone Figueiredo, Teresa Moura, Leonel Serrano GordoAbstract:This work is a response to a lack of knowledge of the biology of Raja clavata in southern European waters, particularly in terms of age and growth. Two structures were analysed: dermal denticles and vertebral centra. Six types of dermal denticle were identified in the tail. Among those, small thorns were the most suitable for age determination owing to their fixed position, persistence throughout their lifespan, and defined growth-band pattern. Caudal thorns were more accurate than vertebral centra for age determination and were therefore selected as the most appropriate structure for ageing R. clavata. Based on edge analysis, annual band deposition was verified. The birthdate was established as 1 June based on the prevalence of hyaline edges in age-0 class specimens: prevalence peaked in May and June. Both von Bertalanffy and Gompertz growth models were fitted to age-at-length data, but the former was considered more appropriate based on similarity between the estimated L1 and the maximum size recorded for the species. No significant differences in growth parameters were observed between sexes. The estimated growth parameters were L1 = 1280 mm, k = 0.117 year 21 , and t0 = 20.617 years. The maximum age estimated for R. clavata was 10 years, for a female of length 835 mm.
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diet comparison of four ray species Raja clavata Raja brachyura Raja montagui and leucoRaja naevus caught along the portuguese continental shelf
Aquatic Living Resources, 2006Co-Authors: Ines Farias, Ivone Figueiredo, Leonel Serrano Gordo, Teresa Moura, Ana Neves, Barbara SerrapereiraAbstract:Data on the diet of species are important for understanding ecosystem dynamics and are fundamental for the implementation of recent approaches in stock assessment and consequently for the establishment of more ecological management measures. In mainland Portugal, as in most European countries, skates and rays represent an important proportion of commercial landings. The four main species landed are Raja clavata and Raja brachyura, followed by LeucoRaja naevus and Raja montagui. This paper analyses their diets based on the examination of stomach contents. Food items were identified to the lowest identifiable taxon and were further assembled into major taxonomic groups designated as prey. Intra- and interspecific comparisons were made according to size and sex. All four species had generalized diets with differences in prey preference among them. Decapods and bony fish were the most frequent prey. Furthermore, an ontogenetic dietary shift was evident in all species at around 45−55 cm total length. Both intra- and interspecific differences observed seem to be related to size and morphological characteristics of the species, as well as type of dentition. These variations allow different species, as well as small and large specimens from the same species, to exploit a larger diversity of habitats.
Santiago P. Aubourg - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of a slurry ice system for the commercialization of ray (Raja clavata): Effects on spoilage mechanisms directly affecting quality loss and shelf-life
Lwt - Food Science and Technology, 2008Co-Authors: Begoña Múgica, Jorge Barros-velázquez, José M. Miranda, Santiago P. AubourgAbstract:The application of slurry ice, a biphasic system formed by small spherical ice crystals surrounded by seawater at sub-zero temperature, was evaluated as a new storage method for ray (Raja clavata), the elasmobranch fish species that exhibits highest commercial value in the European food markets. This advanced technique was used to compare with a control batch stored 10 days in flake ice. The results obtained in the sensory analysis indicated a significant extension of the overall quality (A class fish) from 3 days (flake ice) to 6 days (slurry ice). The development of ammonia external odour was the limiting parameter in both batches and was correlated with the activity of the endogenous mechanisms involved in the degradation of proteins and non-protein-nitrogen (NPN) rather than with the activity of proteolytic microorganisms. Storage of ray in slurry ice significantly (P
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evaluation of a slurry ice system for the commercialization of ray Raja clavata effects on spoilage mechanisms directly affecting quality loss and shelf life
Lwt - Food Science and Technology, 2008Co-Authors: Begoña Múgica, José M. Miranda, Jorge Barrosvelazquez, Santiago P. AubourgAbstract:The application of slurry ice, a biphasic system formed by small spherical ice crystals surrounded by seawater at sub-zero temperature, was evaluated as a new storage method for ray (Raja clavata), the elasmobranch fish species that exhibits highest commercial value in the European food markets. This advanced technique was used to compare with a control batch stored 10 days in flake ice. The results obtained in the sensory analysis indicated a significant extension of the overall quality (A class fish) from 3 days (flake ice) to 6 days (slurry ice). The development of ammonia external odour was the limiting parameter in both batches and was correlated with the activity of the endogenous mechanisms involved in the degradation of proteins and non-protein-nitrogen (NPN) rather than with the activity of proteolytic microorganisms. Storage of ray in slurry ice significantly (P<0.05) slowed down both biochemical (as estimated by the follow-up of the pH, TVB-N and K-value evolution) and microbial degradation mechanisms (estimated by the development of psychrotrophes and mesophiles counts) in chilled ray muscle. According to the parameters evaluated, storage of ray in slurry ice extends the shelf-life of this elasmobranch fish species due to a better maintenance of sensory, biochemical and microbiological quality, thus facilitating its commercialization.
