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James Thorburn - One of the best experts on this subject based on the ideXlab platform.
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spatial versus temporal structure implications of inter haul variation and relatedness in the north east atlantic spurdog squalus acanthias
Aquatic Conservation-marine and Freshwater Ecosystems, 2018Co-Authors: James Thorburn, Cecilia Pinto, Victoria Bendall, Stuart Hetherington, Noble Leslie, David M Bailey, Francis Neat, Rosie Jones, Cath S JonesAbstract:ACKNOWLEDGEMENTS Our thanks go to Gordon Goldie, Willie Kennedy, Stuart Cresswell, and Trevor Ryder for assisting with sample collection, and to Margaret Wallace for her help with all stages of labwork. This work received funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland), and their support is gratefully acknowledged. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. The spurdog tissue samples collected by CEFAS were part of the European Fisheries Fund project ‘Shark By‐Watch UK’ and two DEFRA‐funded projects: MF047 ‘Spurdog, Porbeagle and common skate by‐catch and discard reduction’ and M5201a ‘Assessing the survivability of bycaught Porbeagle and spurdog and furthering our understanding of their movement patterns in UK marine waters’. We also thank the anonymous reviewers whose comments helped improve this article. FUNDING This work received funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland), and their support is gratefully acknowledged. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. The spurdog tissue samples collected by CEFAS were part of the European Fisheries Fund project ‘Shark By‐Watch UK’ and two DEFRA‐funded projects: MF047 ‘Spurdog, Porbeagle and common skate by‐catch and discard reduction’ and M5201a ‘Assessing the survivability of bycaught Porbeagle and spurdog and furthering our understanding of their movement patterns in UK marine waters’.
Cath S Jones - One of the best experts on this subject based on the ideXlab platform.
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spatial versus temporal structure implications of inter haul variation and relatedness in the north east atlantic spurdog squalus acanthias
Aquatic Conservation-marine and Freshwater Ecosystems, 2018Co-Authors: James Thorburn, Cecilia Pinto, Victoria Bendall, Stuart Hetherington, Noble Leslie, David M Bailey, Francis Neat, Rosie Jones, Cath S JonesAbstract:ACKNOWLEDGEMENTS Our thanks go to Gordon Goldie, Willie Kennedy, Stuart Cresswell, and Trevor Ryder for assisting with sample collection, and to Margaret Wallace for her help with all stages of labwork. This work received funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland), and their support is gratefully acknowledged. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. The spurdog tissue samples collected by CEFAS were part of the European Fisheries Fund project ‘Shark By‐Watch UK’ and two DEFRA‐funded projects: MF047 ‘Spurdog, Porbeagle and common skate by‐catch and discard reduction’ and M5201a ‘Assessing the survivability of bycaught Porbeagle and spurdog and furthering our understanding of their movement patterns in UK marine waters’. We also thank the anonymous reviewers whose comments helped improve this article. FUNDING This work received funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland), and their support is gratefully acknowledged. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. The spurdog tissue samples collected by CEFAS were part of the European Fisheries Fund project ‘Shark By‐Watch UK’ and two DEFRA‐funded projects: MF047 ‘Spurdog, Porbeagle and common skate by‐catch and discard reduction’ and M5201a ‘Assessing the survivability of bycaught Porbeagle and spurdog and furthering our understanding of their movement patterns in UK marine waters’.
Steven E. Campana - One of the best experts on this subject based on the ideXlab platform.
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JD: Shark Predation on Migrating Adult American Eels (Anguilla rostrata) in the Gulf of St. Lawrence. Plos One 2012, 7(10):e46830.Submit your next manuscript to BioMed Central and take full advantage of: • Convenient online submission • Thorough peer
2016Co-Authors: Jose ́ Benchetrit, Steven E. Campana, Martin Castonguay, Kim Aarestrup, Michael J. W. Stokesbury, Julian J. DodsonAbstract:In an attempt to document the migratory pathways and the environmental conditions encountered by American eels during their oceanic migration to the Sargasso Sea, we tagged eight silver eels with miniature satellite pop-up tags during their migration from the St. Lawrence River in Québec, Canada. Surprisingly, of the seven tags that successfully transmitted archived data, six were ingested by warm-gutted predators, as observed by a sudden increase in water temperature. Gut temperatures were in the range of 20 to 25uC—too cold for marine mammals but within the range of endothermic fish. In order to identify the eel predators, we compared their vertical migratory behavior with those of satellite-tagged Porbeagle shark and bluefin tuna, the only endothermic fishes occurring non-marginally in the Gulf of St. Lawrence. We accurately distinguished between tuna and shark by using the behavioral criteria generated by comparing the diving behavior of these two species with those of our unknown predators. Depth profile characteristics of most eel predators more closely resembled those of sharks than those of tuna. During the first days following tagging, all eels remained in surface waters and did not exhibit diel vertical migrations. Three eels were eaten at this time. Two eels exhibited inverse diel vertical migrations (at surface during the day) during several days prior to predation. Four eels were eaten during daytime, whereas the two night-predation events occurred at full moon. Although tagging itself may contribute to increasing the eel’s susceptibility to predation, we discuss evidence suggesting that predation of silver-stage American eels by Porbeagle shark
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Transboundary movements, unmonitored fishing mortality, and ineffective international fisheries management pose risks for pelagic sharks in the Northwest Atlantic
Canadian Journal of Fisheries and Aquatic Sciences, 2016Co-Authors: Steven E. CampanaAbstract:The shortfin mako (Isurus oxyrinchus), Porbeagle (Lamna nasus), and blue shark (Prionace glauca) are three frequently caught shark species in the northwestern Atlantic Ocean. Satellite tagging studies show that all three species range widely across many national boundaries but spend up to 92% of their time on the high seas, where they are largely unregulated and unmonitored. All are caught in large numbers by swordfish and tuna fishing fleets from a large number of nations, usually unintentionally, and all are unproductive by fish standards, which makes them particularly sensitive to fishing pressure. Landing statistics that grossly underrepresent actual catches, unreported discards that often exceed landings, and high discard mortality rates are threats to the populations and roadblocks to useful population monitoring. The influence of these threats is greatly magnified by inattention and ineffective management from the responsible management agency, the International Commission for the Conservation of A...
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North American Journal of Fisheries Management 22:106–121, 2002 q Copyright by the American Fisheries Society 2002 Population Dynamics of the Porbeagle in the Northwest Atlantic Ocean
2015Co-Authors: Steven E. Campana, Lisa J. Natanson, Joseph J. Mello, Nancy E. Kohler, Harold L. Pratt, Christopher F. Jensen, Warren Joyce, Linda Marks, Sigmund MyklevollAbstract:Abstract.—A virgin population of Porbeagles Lamna nasus in the northwest Atlantic Ocean supported annual catches of up to 9,000 metric tons (mt) in the early 1960s before the fishery collapsed in 1967. Low and apparently sustainable catches of about 350 mt in the 1970s and 1980s allowed the stock to partially rebuild before a new fishery arose in the early 1990s. The response of the population to this renewed fishing pressure has been unclear until now. However, a new population dynamics analysis suggests that population abundance has once again declined. On the basis of more than 140,000 length measurements, an extensive catch rate index, a confirmed growth model, and a catch-at-age matrix, it appears that at least 90 % of the sexually mature population has been lost as fishing mortality has increased. Independent measures of fishing mortality (F) based on Petersen analysis of tag-recaptures, Paloheimo Zs, and a population model all suggest that fishing mortality was about 0.20 in 2000. Biological reference points based on life table analysis indicate that fishing at F0.1 5 0.18 will result in population collapse, that F 5 0.08 corresponds to zero population growth, and that fishing mortality at maximum sustainable yield is about 0.04. Porbeagles have a low pup production rate and mature considerably after the age at which they first appear in the fishery. In light of the very low numbers of mature females no
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Shark predation on migrating adult american eels (Anguilla rostrata) in the Gulf of St. Lawrence.
PLoS ONE, 2012Co-Authors: Mélanie Béguer-pon, Steven E. Campana, José Benchetrit, Martin Castonguay, Kim Aarestrup, Michael J. W. Stokesbury, Julian J. DodsonAbstract:In an attempt to document the migratory pathways and the environmental conditions encountered by American eels during their oceanic migration to the Sargasso Sea, we tagged eight silver eels with miniature satellite pop-up tags during their migration from the St. Lawrence River in Quebec, Canada. Surprisingly, of the seven tags that successfully transmitted archived data, six were ingested by warm-gutted predators, as observed by a sudden increase in water temperature. Gut temperatures were in the range of 20 to 25°C—too cold for marine mammals but within the range of endothermic fish. In order to identify the eel predators, we compared their vertical migratory behavior with those of satellite-tagged Porbeagle shark and bluefin tuna, the only endothermic fishes occurring non-marginally in the Gulf of St. Lawrence. We accurately distinguished between tuna and shark by using the behavioral criteria generated by comparing the diving behavior of these two species with those of our unknown predators. Depth profile characteristics of most eel predators more closely resembled those of sharks than those of tuna. During the first days following tagging, all eels remained in surface waters and did not exhibit diel vertical migrations. Three eels were eaten at this time. Two eels exhibited inverse diel vertical migrations (at surface during the day) during several days prior to predation. Four eels were eaten during daytime, whereas the two night-predation events occurred at full moon. Although tagging itself may contribute to increasing the eel's susceptibility to predation, we discuss evidence suggesting that predation of silver-stage American eels by Porbeagle sharks may represent a significant source of mortality inside the Gulf of St. Lawrence and raises the possibility that eels may represent a reliable, predictable food resource for Porbeagle sharks.
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Actual vertical migration profiles of known predators.
2012Co-Authors: Mélanie Béguer-pon, Steven E. Campana, José Benchetrit, Martin Castonguay, Kim Aarestrup, Michael J. W. Stokesbury, Julian J. DodsonAbstract:Upper panel (a): a Porbeagle shark vertical profile (#07A0946) and lower panel (b): a bluefin tuna vertical profile (#10A613). The gray parts represent night period.
Juan A. Waessle - One of the best experts on this subject based on the ideXlab platform.
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hotspots for Porbeagle shark lamna nasus bycatch in the southwestern atlantic 51 s 57 s
Canadian Journal of Fisheries and Aquatic Sciences, 2017Co-Authors: Federico Cortés, Juan A. WaessleAbstract:Fisheries bycatch can severely affect the population status of species with low resilience such as sharks. Bycatch monitoring is an important issue for the development of conservation and management plans for these species. The main objectives of this study were to quantify and model the spatiotemporal trend of bycatch for Porbeagle shark (Lamna nasus) in the Argentinean surimi trawl fleet to identify hotspots in the southwestern Atlantic Ocean. Using onboard observer data, we have demonstrated that L. nasus was usually caught as bycatch by the surimi trawl fleet operating in the southern limits of the southwestern Atlantic (51°S–57°S), representing an important part of the reported catch for the Atlantic Ocean. Delta and Tweedie models indicated that bycatch had a relatively stable trend, was concentrated in a limited region of the study area, and was associated with spatiotemporal, operational, environmental, and prey availability variables. The model with the best predictive capability used for the spa...
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Hotspots for Porbeagle shark (Lamna nasus) bycatch in the southwestern Atlantic (51°S–57°S)
Canadian Journal of Fisheries and Aquatic Sciences, 2017Co-Authors: Federico Cortés, Juan A. WaessleAbstract:Fisheries bycatch can severely affect the population status of species with low resilience such as sharks. Bycatch monitoring is an important issue for the development of conservation and management plans for these species. The main objectives of this study were to quantify and model the spatiotemporal trend of bycatch for Porbeagle shark (Lamna nasus) in the Argentinean surimi trawl fleet to identify hotspots in the southwestern Atlantic Ocean. Using onboard observer data, we have demonstrated that L. nasus was usually caught as bycatch by the surimi trawl fleet operating in the southern limits of the southwestern Atlantic (51°S–57°S), representing an important part of the reported catch for the Atlantic Ocean. Delta and Tweedie models indicated that bycatch had a relatively stable trend, was concentrated in a limited region of the study area, and was associated with spatiotemporal, operational, environmental, and prey availability variables. The model with the best predictive capability used for the spa...
Noble Leslie - One of the best experts on this subject based on the ideXlab platform.
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Spatial versus temporal structure : implications of inter-haul variation and relatedness in the North East Atlantic Spurdog Squalus acanthias
'Wiley', 2019Co-Authors: Thorburn James, Noble Leslie, Jones Rosie, Neat Francis, Pinto Cecilia, Bendall Victoria, Hetherington Stuart, Bailey, David Mark, Jones CathAbstract:This work received funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland), and their support is gratefully acknowledged. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. The spurdog tissue samples collected by CEFAS were part of the European Fisheries Fund project ‘Shark By‐Watch UK’ and two DEFRA‐funded projects: MF047 ‘Spurdog, Porbeagle and common skate by‐catch and discard reduction’ and M5201a ‘Assessing the survivability of bycaught Porbeagle and spurdog and furthering our understanding of their movement patterns in UK marine waters’.1. Micro-population processes, such as gene flow, operating within geographic regions are often poorly understood despite their potential to impact stock structure and sustainability. This is especially true for highly mobile species, such as elasmobranchs, where the potential for spatial overlap of regional populations is increased due to higher movement capabilities. A lack of information on these processes means management plans rarely consider spatio-temporal structure. 2. Spurdog (Squalus acanthias) are globally distributed throughout temperate regions yet there is an apparent lack of gene flow between ocean basins. In the North-east Atlantic, there is little work on gene flow within the region which is currently managed as a single stock that is estimated to be at 19% compared to 1905. Some evidence from this region suggests population processes which have the potential to cause structuring. 3. Population structure of NE Atlantic spurdog was investigated using an 828-bp fragment of the mitochondrial DNA control region and seven focal polymorphic microsatellite markers. Samples from 295 individuals from eight locations throughout UK waters were used in this study. 4. Overall, mitochondrial sequences suggested some regional differentiation. Genetic diversity was comparable with that reported in previous studies of spurdog. Haplotype diversity (0.782 - 1) is amongst the highest observed for an elasmobranch. Microsatellite markers suggested a high level of relatedness was responsible for regional population structuring. There was no apparent spatial structure after removal of ‘full sibling’ relationships. 5. Inter-haul variation from Celtic Sea samples is suggestive of sub-populations and aggregation events which may have important implications for fisheries conservation of this, and other, elasmobranch species.PostprintPeer reviewe
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spatial versus temporal structure implications of inter haul variation and relatedness in the north east atlantic spurdog squalus acanthias
Aquatic Conservation-marine and Freshwater Ecosystems, 2018Co-Authors: James Thorburn, Cecilia Pinto, Victoria Bendall, Stuart Hetherington, Noble Leslie, David M Bailey, Francis Neat, Rosie Jones, Cath S JonesAbstract:ACKNOWLEDGEMENTS Our thanks go to Gordon Goldie, Willie Kennedy, Stuart Cresswell, and Trevor Ryder for assisting with sample collection, and to Margaret Wallace for her help with all stages of labwork. This work received funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland), and their support is gratefully acknowledged. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. The spurdog tissue samples collected by CEFAS were part of the European Fisheries Fund project ‘Shark By‐Watch UK’ and two DEFRA‐funded projects: MF047 ‘Spurdog, Porbeagle and common skate by‐catch and discard reduction’ and M5201a ‘Assessing the survivability of bycaught Porbeagle and spurdog and furthering our understanding of their movement patterns in UK marine waters’. We also thank the anonymous reviewers whose comments helped improve this article. FUNDING This work received funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland), and their support is gratefully acknowledged. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. The spurdog tissue samples collected by CEFAS were part of the European Fisheries Fund project ‘Shark By‐Watch UK’ and two DEFRA‐funded projects: MF047 ‘Spurdog, Porbeagle and common skate by‐catch and discard reduction’ and M5201a ‘Assessing the survivability of bycaught Porbeagle and spurdog and furthering our understanding of their movement patterns in UK marine waters’.
