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Philippe Gaspar - One of the best experts on this subject based on the ideXlab platform.
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Fishing Activity of tuna purse seiners estimated from vessel monitoring system vms data
Canadian Journal of Fisheries and Aquatic Sciences, 2011Co-Authors: Nicolas Bez, Emily Walker, Daniel Gaertner, Jacques Rivoirard, Philippe GasparAbstract:In the lack of fishery-independent information, catch per unit of effort (CPUE) is the conventional abundance index. In the case of the tropical tuna purse seine fisheries, a critical difficulty li...
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Fishing Activity of tuna purse seiners estimated from vms dada and validated by observers data
Collective Volume of Scientific Papers ICCAT, 2010Co-Authors: Emily Walker, Daniel Gaertner, Philippe Gaspar, Nicolas BezAbstract:1 SUMMARY In the lack of direct estimate of tuna abundance, the French tropical tuna fleet of purse-seiners provides a way to monitor the tuna stocks particularly through the calculation of Catch per Unit of Effort (CPUE). The objective of this study was to analyze the individual track of purse seiners with the aim to identify which part of the searching behaviour should be used to perform the Fishing effort. In this context, Vessel Monitoring Systems (VMS) data are useful to analyse the different Fishing activities of a purse seiner at a small scale (i.e.. stop, track and cruise), generally embedded into the concept of Fishing effort. A state-space model (run in a Bayesian framework) was applied to speeds and turning angles from Vessel Monitoring Systems (VMS) data, to identify the different "states" of the Fishing behaviour of a purse seiner over a Fishing trip. Then a threshold was fitted to distinguish the activities "Fishing" and "stop" without Fishing (from the "still" state), "tracking" (from "meander"), and "cruising" (from "straight"). On a subset of VMS data corresponding to observers' data, some differences of Fishing efforts between Fishing on free-swimming schools and schools associated with FAD (Fish Aggregating Devices) are highlighted. RESUME Etant donnees les difficultes d'estimation directe de l'abondance de thon, la flottille francaise de thoniers senneurs tropicaux offre la possibilite de surveiller les stocks de thon, particulierement grâce au calcul de Capture par unite d'effort (CPUE). L'objectif de cette etude etait d'analyser la trajectoire individuelle des thoniers senneurs, dans le but d'identifier quelle parties du comportement de recherche doivent etre utilisees dans le calcul de l'effort de peche. Dans ce contexte, les donnees de Vessel Monitoring Systems (VMS) sont utiles pour analyser les differentes activites de peche d'un thonier senneur a fine echelle (c'est-a-dire arret, recherche active, route-recherche), generalement inclus dans le concept d'effort de peche. Un modele a espace d'etat (avec une approche bayesienne) a ete applique aux vitesses et angles de changement de direction issus des donnees de Vessel Monitoring Systems (VMS) pour identifier les differents etats du comportement de peche d'un thonier senneur pendant une maree. Ensuite un seuil a ete ajuste pour distinguer les activites de « peche » et d' « arret » sans peche (a partir de l'etat « immobile »), « recherche active » (a partir de « sinueux »), et « route-recherche » (a partir de « tout droit »). Sur un sous-jeu de donnees VMS correspondant aux donnees Observateurs, certaines differences d'effort de peche entre bancs peches sur Bancs Libres et ceux peches sur bancs associes aux DCP (Dispositifs de Concentration de Poisson) sont mises en evidence. RESUMEN
Lee G. Murray - One of the best experts on this subject based on the ideXlab platform.
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Filling the gap: Using fishers’ knowledge to map the extent and intensity of Fishing Activity
Marine environmental research, 2017Co-Authors: Claire L. Szostek, Lee G. Murray, Ewen Bell, Michel J. KaiserAbstract:Abstract Knowledge of the extent and intensity of Fishing activities is critical to inform management in relation to Fishing impacts on marine conservation features. Such information can also provide insight into the potential socio-economic impacts of closures (or other restrictions) of Fishing grounds that could occur through the future designation of Marine Conservation Zones (MCZs). We assessed the accuracy and validity of Fishing effort data (spatial extent and relative effort) obtained from Fishers’ Local Knowledge (LK) data compared to that derived from Vessel Monitoring System (VMS) data for a high-value shellfish fishery, the king scallop ( Pecten maximus L.) dredge fishery in the English Channel. The spatial distribution of Fishing effort from LK significantly correlated with VMS data and the correlation increased with increasing grid cell resolution. Using a larger grid cell size for data aggregation increases the estimation of the total area of seabed impacted by the fishery. In the absence of historical VMS data for vessels ≤15 m LOA (Length Overall), LK data for the inshore fleet provided important insights into the relative effort of the inshore (
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Implications of using alternative methods of vessel monitoring system (VMS) data analysis to describe Fishing activities and impacts
ICES Journal of Marine Science, 2012Co-Authors: Gwladys I. Lambert, Niels T. Hintzen, Simon Jennings, Jan G. Hiddink, Hilmar Hinz, Michael J. Kaiser, Lee G. MurrayAbstract:Understanding the spatial distribution and intensity of Fishing Activity is a prerequisite for estimating Fishing impacts on seabed biota and habitats. Vessel monitoring system data provide information on Fishing Activity at large spatial scales. However, successive position records can be too infrequent to describe the complex movements Fishing vessels make. High-frequency position data were collected to evaluate how polling frequency and the method of analysis influenced the estimates of Fishing impact on the seabed and associated epifaunal communities. Comparisons of known positions with predictions from track interpolation revealed that the performance of interpolation depended on fleet behaviour. Descriptions and indicators of Fishing intensity were influenced significantly by the analytical methods (track reconstruction, density of position records) and grid-cell resolution used for the analysis. These factors can lead to an underestimation of Fishing impact on epifaunal communities. It is necessary to correct for such errors to quantify the effects of Fishing on various ecosystem components and hence to inform ecosystem-based management. Polling at intervals of 30 min would provide a desirable compromise between achieving precise estimates of Fishing impacts on the seabed and minimizing the cost of data collection and handling.
Nicolas Bez - One of the best experts on this subject based on the ideXlab platform.
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Fishing Activity of tuna purse seiners estimated from vessel monitoring system vms data
Canadian Journal of Fisheries and Aquatic Sciences, 2011Co-Authors: Nicolas Bez, Emily Walker, Daniel Gaertner, Jacques Rivoirard, Philippe GasparAbstract:In the lack of fishery-independent information, catch per unit of effort (CPUE) is the conventional abundance index. In the case of the tropical tuna purse seine fisheries, a critical difficulty li...
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Fishing Activity of tuna purse seiners estimated from vms dada and validated by observers data
Collective Volume of Scientific Papers ICCAT, 2010Co-Authors: Emily Walker, Daniel Gaertner, Philippe Gaspar, Nicolas BezAbstract:1 SUMMARY In the lack of direct estimate of tuna abundance, the French tropical tuna fleet of purse-seiners provides a way to monitor the tuna stocks particularly through the calculation of Catch per Unit of Effort (CPUE). The objective of this study was to analyze the individual track of purse seiners with the aim to identify which part of the searching behaviour should be used to perform the Fishing effort. In this context, Vessel Monitoring Systems (VMS) data are useful to analyse the different Fishing activities of a purse seiner at a small scale (i.e.. stop, track and cruise), generally embedded into the concept of Fishing effort. A state-space model (run in a Bayesian framework) was applied to speeds and turning angles from Vessel Monitoring Systems (VMS) data, to identify the different "states" of the Fishing behaviour of a purse seiner over a Fishing trip. Then a threshold was fitted to distinguish the activities "Fishing" and "stop" without Fishing (from the "still" state), "tracking" (from "meander"), and "cruising" (from "straight"). On a subset of VMS data corresponding to observers' data, some differences of Fishing efforts between Fishing on free-swimming schools and schools associated with FAD (Fish Aggregating Devices) are highlighted. RESUME Etant donnees les difficultes d'estimation directe de l'abondance de thon, la flottille francaise de thoniers senneurs tropicaux offre la possibilite de surveiller les stocks de thon, particulierement grâce au calcul de Capture par unite d'effort (CPUE). L'objectif de cette etude etait d'analyser la trajectoire individuelle des thoniers senneurs, dans le but d'identifier quelle parties du comportement de recherche doivent etre utilisees dans le calcul de l'effort de peche. Dans ce contexte, les donnees de Vessel Monitoring Systems (VMS) sont utiles pour analyser les differentes activites de peche d'un thonier senneur a fine echelle (c'est-a-dire arret, recherche active, route-recherche), generalement inclus dans le concept d'effort de peche. Un modele a espace d'etat (avec une approche bayesienne) a ete applique aux vitesses et angles de changement de direction issus des donnees de Vessel Monitoring Systems (VMS) pour identifier les differents etats du comportement de peche d'un thonier senneur pendant une maree. Ensuite un seuil a ete ajuste pour distinguer les activites de « peche » et d' « arret » sans peche (a partir de l'etat « immobile »), « recherche active » (a partir de « sinueux »), et « route-recherche » (a partir de « tout droit »). Sur un sous-jeu de donnees VMS correspondant aux donnees Observateurs, certaines differences d'effort de peche entre bancs peches sur Bancs Libres et ceux peches sur bancs associes aux DCP (Dispositifs de Concentration de Poisson) sont mises en evidence. RESUMEN
Brendan J Godley - One of the best experts on this subject based on the ideXlab platform.
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a step towards seascape scale conservation using vessel monitoring systems vms to map Fishing Activity
PLOS ONE, 2007Co-Authors: Matthew J Witt, Brendan J GodleyAbstract:Background Conservation of marine ecosystems will require a holistic understanding of fisheries with concurrent spatial patterns of biodiversity. Methodology/Principal Findings Using data from the UK Government Vessel Monitoring System (VMS) deployed on UK-registered large Fishing vessels we investigate patterns of fisheries Activity on annual and seasonal scales. Analysis of VMS data shows that regions of the UK European continental shelf (i.e. Western Channel and Celtic Sea, Northern North Sea and the Goban Spur) receive consistently greater fisheries pressure than the rest of the UK continental shelf Fishing zone. Conclusions/Significance VMS provides a unique and independent method from which to derive patterns of spatially and temporally explicit fisheries Activity. Such information may feed into ecosystem management plans seeking to achieve sustainable fisheries while minimising putative risk to non-target species (e.g. cetaceans, seabirds and elasmobranchs) and habitats of conservation concern. With multilateral collaboration VMS technologies may offer an important solution to quantifying and managing ecosystem disturbance, particularly on the high-seas.
Emily Walker - One of the best experts on this subject based on the ideXlab platform.
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Fishing Activity of tuna purse seiners estimated from vessel monitoring system vms data
Canadian Journal of Fisheries and Aquatic Sciences, 2011Co-Authors: Nicolas Bez, Emily Walker, Daniel Gaertner, Jacques Rivoirard, Philippe GasparAbstract:In the lack of fishery-independent information, catch per unit of effort (CPUE) is the conventional abundance index. In the case of the tropical tuna purse seine fisheries, a critical difficulty li...
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Fishing Activity of tuna purse seiners estimated from vms dada and validated by observers data
Collective Volume of Scientific Papers ICCAT, 2010Co-Authors: Emily Walker, Daniel Gaertner, Philippe Gaspar, Nicolas BezAbstract:1 SUMMARY In the lack of direct estimate of tuna abundance, the French tropical tuna fleet of purse-seiners provides a way to monitor the tuna stocks particularly through the calculation of Catch per Unit of Effort (CPUE). The objective of this study was to analyze the individual track of purse seiners with the aim to identify which part of the searching behaviour should be used to perform the Fishing effort. In this context, Vessel Monitoring Systems (VMS) data are useful to analyse the different Fishing activities of a purse seiner at a small scale (i.e.. stop, track and cruise), generally embedded into the concept of Fishing effort. A state-space model (run in a Bayesian framework) was applied to speeds and turning angles from Vessel Monitoring Systems (VMS) data, to identify the different "states" of the Fishing behaviour of a purse seiner over a Fishing trip. Then a threshold was fitted to distinguish the activities "Fishing" and "stop" without Fishing (from the "still" state), "tracking" (from "meander"), and "cruising" (from "straight"). On a subset of VMS data corresponding to observers' data, some differences of Fishing efforts between Fishing on free-swimming schools and schools associated with FAD (Fish Aggregating Devices) are highlighted. RESUME Etant donnees les difficultes d'estimation directe de l'abondance de thon, la flottille francaise de thoniers senneurs tropicaux offre la possibilite de surveiller les stocks de thon, particulierement grâce au calcul de Capture par unite d'effort (CPUE). L'objectif de cette etude etait d'analyser la trajectoire individuelle des thoniers senneurs, dans le but d'identifier quelle parties du comportement de recherche doivent etre utilisees dans le calcul de l'effort de peche. Dans ce contexte, les donnees de Vessel Monitoring Systems (VMS) sont utiles pour analyser les differentes activites de peche d'un thonier senneur a fine echelle (c'est-a-dire arret, recherche active, route-recherche), generalement inclus dans le concept d'effort de peche. Un modele a espace d'etat (avec une approche bayesienne) a ete applique aux vitesses et angles de changement de direction issus des donnees de Vessel Monitoring Systems (VMS) pour identifier les differents etats du comportement de peche d'un thonier senneur pendant une maree. Ensuite un seuil a ete ajuste pour distinguer les activites de « peche » et d' « arret » sans peche (a partir de l'etat « immobile »), « recherche active » (a partir de « sinueux »), et « route-recherche » (a partir de « tout droit »). Sur un sous-jeu de donnees VMS correspondant aux donnees Observateurs, certaines differences d'effort de peche entre bancs peches sur Bancs Libres et ceux peches sur bancs associes aux DCP (Dispositifs de Concentration de Poisson) sont mises en evidence. RESUMEN