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| Registros recuperados: 20 | |
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| Granger, Victoria; Fromentin, Jean-marc; Bez, Nicolas; Relini, Giulio; Meynard, Christine N.; Gaertner, Jean-claude; Maiorano, Porzia; Garcia Ruiz, Cristina; Follesa, Cristina; Gristina, Michele; Peristeraki, Panagiota; Brind'Amour, Anik; Carbonara, Pierluigi; Charilaou, Charis; Esteban, Antonio; Jadaud, Angelique; Joksimovic, Aleksandar; Kallianiotis, Argyris; Kolitari, Jerina; Manfredi, Chiara; Massuti, Enric; Mifsud, Roberta; Quetglas, Antoni; Refes, Wahid; Sbrana, Mario; Vrgoc, Nedo; Spedicato, Maria Teresa; Merigot, Bastien. |
| Increasing human pressures and global environmental change may severely affect the diversity of species assemblages and associated ecosystem services. Despite the recent interest in phylogenetic and functional diversity, our knowledge on large spatio-temporal patterns of demersal fish diversity sampled by trawling remains still incomplete, notably in the Mediterranean Sea, one of the most threatened marine regions of the world. We investigated large spatio-temporal diversity patterns by analysing a dataset of 19,886 hauls from 10 to 800 m depth performed annually during the last two decades by standardized scientific bottom trawl field surveys across the Mediterranean Sea, within the MEDITS program. A multi-component (eight diversity indices) and... |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00216/32743/31322.pdf |
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| Assali, Camille; Bez, Nicolas; Tremblay, Yann. |
| Seabirds are known to concentrate on prey patches or at predators aggregations standing for potential feeding opportunities. They may search for prey using olfaction or by detecting visually feeding conspecifics and sub-surface predators, or even boats. Thus, they might form a foraging network. We hypothesized that conditionally to the existence of a foraging network, the visual detection ability of seabirds should have a bearing on their medium-scale distribution at sea. Using a fishing-boat radar to catch the instantaneous distribution of seabirds groups within 30 km around the vessel, we conducted a spatial clustering of the seabird-echoes. We found 7,657 clusters (i.e. aggregations of echoes), lasting less than 15 minutes and measuring 9.2 km in... |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00625/73703/76150.pdf |
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| Mannocci, Laura; Forget, Fabien; Travassos Tolotti, Mariana; Bach, Pascal; Bez, Nicolas; Demarcq, Herve; Kaplan, David; Sabarros, Philippe; Simier, Monique; Capello, Manuela; Dagorn, Laurent. |
| Fisheries observer programs represent the most reliable way to collect data on fisheries bycatch. However, their limited coverage leads to important data gaps that preclude bycatch mitigation at the basin scale. Habitat models developed from available fisheries observer programs offer a potential solution to fill these data gaps. We focus on tropical tuna purse seine fisheries (TTPSF) that span across the tropics and extensively rely on floating objects (FOBs) for catching tuna schools, leading to the bycatch of other species associated with these objects. Bycatch under floating objects is dominated by five species, including the vulnerable silky shark Carcharhinus falciformis and four bony fishes (oceanic triggerfish Canthidermis maculata, rainbow runner... |
| Tipo: Text |
Palavras-chave: Bycatch; Habitat modelling; Hotspots; Fisheries observer programs; Geographical extrapolation; Tropical oceans. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00662/77385/78986.pdf |
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| Petitgas, Pierre; Woillez, Mathieu; Rivoirard, J; Renard, D; Bez, Nicolas. |
| The course in Fontainebleau was a great experience which provided helpful technical support for my work on the variation of spatial distributions of fish and increased my repertoire of methods. In particular, I am now able to deal with a huge amount of trawl survey station data, analyse the structure in their spatial and temporal variability, and derive maps from sample datapoints. In addition, I also see how useful it can be for other hot topics such as plastics in the ocean or impacts of oil rigs, especially during a time when environmental issues receive increasing public attention. During the course, I was also able to socialize and meet a variety of interesting, smart, and friendly scientists from all over the world. Courses such as the one in... |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00585/69732/67621.pdf |
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| Rufino, Marta; Bez, Nicolas; Brind'Amour, Anik. |
| Spatial indicators are used to quantify the state of species and ecosystem status, that is the impacts of climate and anthropogenic changes, as well as to comprehend species ecology. These metrics are thus, determinant to the stakeholder’s decisions on the conservation measures to be implemented. A detailed review of the literature (55 papers) showed that 18 spatial indicators were commonly used in marine ecology. Those indicators were than characterized and studied in detail, based on its application to empirical data (a time series of 35 marine species spatial distributions, sampled either with a random stratified survey or a regular transects surveys). The results suggest that the indicators can be grouped into three classes, that summarize the way the... |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00469/58087/60490.pdf |
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| Rufino, Marta; Bez, Nicolas; Brind'Amour, Anik. |
| Spatial indicators are widely used to monitor species and are essential to management and conservation. In the present study, we tested the ability of 11 spatial indicators to quantify changes in species’ geographic patterns: (1) spatial displacement of a patch of biomass (‘shift’), (2) a spatial decrease in a patch, accompanied either by a loss of biomass (‘shrink0’) or (3) a relocation of the same biomass (‘shrink1’), and (4) splitting of a patch into smaller patches (‘split’). The geographic changes were simulated by manipulating the spatial distributions of the demersal species (observed during bottom trawl surveys). Hence, the spatial distributions of the latter being used as input data on which the manipulations were done. Additionally, other aspects... |
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Palavras-chave: Spatial metrics; Monitoring; Marine conservation; Fisheries management. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00625/73684/73148.pdf |
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| Woillez, M; Poulard, Jean-charles; Rivoirard, Jacques; Petitgas, Pierre; Bez, Nicolas. |
| A series of candidate statistical indices is used in an attempt to capture spatial patterns of fish populations from research survey data. To handle diffuse population limits, indices are designed not to depend on arbitrary delineation of the domain. They characterize the location (centre of gravity and spatial patches), the occupation of space (inertia, isotropy, positive area, spreading area, and equivalent area), statistical dispersion (Gini index and coefficient of variation of strictly positive densities), and microstructure. Collocation between different ages and years is summarized by a global index of collocation. Indices are estimated for hake from a bottom-trawl data series in the Bay of Biscay in autumn of 1987-2004. The study provides a... |
| Tipo: Text |
Palavras-chave: Spatial indices; European hake; Bay of Biscay. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2671.pdf |
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| Gascuel, D.; Bez, Nicolas; Forest, Andre; Guillotreau, P.; Laloe, F.; Lobry, Jeremy; Mahevas, Stephanie; Mesnil, Benoit; Rivot, Etienne; Rochette, S.; Trenkel, Verena. |
| We, members of the Association Francaise d'Halieumetrie, share the conviction that European fisheries have a future. It is time to get off the wrong track. Radical change is required to embark on the path of sustainable development and truly implement the ecosystem approach to fisheries. Today, high fishing pressure is deployed to catch a rare resource, which in return is responsible for the rarity. We must reverse the situation: an abundant resource that affords high catches applying moderate fishing pressure. All management tools and especially all actors must be mobilized. The transition is not simple, and European solidarity must accompany the changes. It is well worth the effort. By reducing fishing pressure, it will be possible in the medium term to... |
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Palavras-chave: Access regulation; Ecosystem approach to fisheries; European Common Fishery Policy; ITQ; MPA; MSY; Management plan; Overcapacity; Subsidies. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00035/14598/11947.pdf |
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| Walker, Emily; Rivoirard, Jacques; Gaspar, Philippe; Bez, Nicolas. |
| In the open ocean, movements of migratory fish populations are typically surveyed using tagging methods that are subject to low sample sizes for archive tags, except for a few notable examples, and poor temporal resolution for conventional tags. Alternatively, one can infer patterns of movement of migratory fish by tracking movements of their predators, i.e., fishing vessels, whose navigational systems (e.g., GPS) provide accurate and frequent VMS (vessel monitoring system) records of movement in pursuit of prey. In this paper, we develop a state-space model that infers the foraging activities of fishing vessels from their tracks. Second, we link foraging activities to probabilities of tuna presence. Finally, using multivariate geostatistical interpolation... |
| Tipo: Text |
Palavras-chave: GPS; Multivariate geostatistics; Presence index; Spatiotemporal distribution; Trajectometry; Tropical tuna; Vessel monitoring system (VMS). |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00610/72249/71048.pdf |
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| Granger, Victoria; Bez, Nicolas; Fromentin, Jean-marc; Meynard, Christine; Jadaud, Angelique; Merigot, Bastien. |
| Mapping diversity indices, that is estimating values in all locations of a given area from some sampled locations, is central to numerous research and applied fields in ecology. Two approaches are used to map diversity indices without including abiotic or biotic variables: (i) the indirect approach, which consists in estimating each individual species distribution over the area, then stacking the distributions of all species to estimate and map a posteriori the diversity index, (ii) the direct approach, which relies on computing a diversity index in each sampled locations and then to interpolate these values to all locations of the studied area for mapping. For both approaches, we document drawbacks from theoretical and practical viewpoints and argue... |
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Palavras-chave: Interpolation methods; Map; Quadratic entropy; Spatial statistics; Species diversity; Species richness; Beta-diversity. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00257/36819/37060.pdf |
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| Drouineau, Hilaire; Lobry, Jeremy; Bez, Nicolas; Travers-trolet, Morgane; Vermard, Youen; Gascuel, Didier. |
| In this introductory paper we highlight key questions that were discussed during the symposium on “Status, functioning and shifts in marine ecosystems” organized by the Association Française d’Halieutique (French Association for Fisheries Sciences, Montpellier, France, July 2015). This symposium illustrated that fisheries science is now working at multiple scales and on all dimensions of socio-ecosystems (ecological, political, sociological, and economic), with a great diversity of approaches and taking into account different levels of complexity while acknowledging diverse sources of uncertainty. We argue that we should go one step further and call for a protean fisheries science to address the deteriorated states of aquatic ecosystems caused by... |
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Palavras-chave: EAFM; Fisheries management; Fisheries science; Marine resources; Models; Uncertainty. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00359/46990/46921.pdf |
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| Bez, Nicolas; Reid, David; Neville, Suzanna; Verin, Yves; Hjellvik, Vidar; Gerritsen, Hans D.. |
| Acoustic data are often collected during bottom trawl surveys. Their use can potentially improve the precision and accuracy of fish abundance estimates if acoustic data collected between trawl stations are consistent with those collected during trawling operations. This question is addressed here through the analysis of 20 bottom trawl surveys (three survey areas and five different survey series) with coincident acoustic measurements during and between trawl stations. Firstly, on-station and underway acoustic data were compared using statistics computed globally over each survey (average vertical profiles, global indices of collocations, and spatial structures) for various combinations of depth layers. Secondly, we focussed on underway acoustic data... |
| Tipo: Text |
Palavras-chave: Gear perturbation; Acoustic; Bottom trawl. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2486.pdf |
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| Cariou, Thibault; Dubroca, Laurent; Vogel, Camille; Bez, Nicolas. |
| L’estuaire de Seine est un habitat essentiel pour les espèces halieutiques emblématiques de la façade Manche-Mer du Nord en sa qualité de nourricerie. Cet estuaire a connu de profondes modifications morphologiques au cours des 30 dernières années des suites d’une forte anthropisation de ces rives. Cet habitat estuarien-côtier, comptant parmi les habitats les plus productifs du milieu marin, joue un rôle central dans le renouvellement des stocks de pêche, en favorisant la croissance et la survie des juvéniles des espèces dites « nourricerie-dépendantes ». Malgré une couverture temporelle très inégale dans les campagnes depuis 30 ans, les suivis des communautés de juvéniles et les observations biotiques (communautés benthiques), abiotiques (hydrodynamisme,... |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00512/62355/66632.pdf |
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| Gimenez, Olivier; Buckland, Stephen T.; Morgan, Byron J. T.; Bez, Nicolas; Bertrand, Sophie; Choquet, Remi; Dray, Stephane; Etienne, Marie-pierre; Fewster, Rachel; Gosselin, Frederic; Merigot, Bastien; Monestiez, Pascal; Morales, Juan M.; Mortier, Frederic; Munoz, Francois; Ovaskainen, Otso; Pavoine, Sandrine; Pradel, Roger; Schurr, Frank M.; Thomas, Len; Thuiller, Wilfried; Trenkel, Verena; De Valpine, Perry; Rexstad, Eric. |
| The desire to predict the consequences of global environmental change has been the driver towards more realistic models embracing the variability and uncertainties inherent in ecology. Statistical ecology has gelled over the past decade as a discipline that moves away from describing patterns towards modelling the ecological processes that generate these patterns. Following the fourth International Statistical Ecology Conference (1–4 July 2014) in Montpellier, France, we analyse current trends in statistical ecology. Important advances in the analysis of individual movement, and in the modelling of population dynamics and species distributions, are made possible by the increasing use of hierarchical and hidden process models. Exciting research perspectives... |
| Tipo: Text |
Palavras-chave: Citizen science; Hidden Markov model; Hierarchical model; Movement ecology; Software package; Spatially explicit capture-recapture; Species distribution modelling; State-space model. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00249/36026/35298.pdf |
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| Saraux, Claire; Fromentin, Jean-marc; Bigot, Jean-louis; Bourdeix, Jean-herve; Morfin, Marie; Roos, David; Van Beveren, Elisabeth; Bez, Nicolas. |
| Understanding the ecological and anthropogenic drivers of population dynamics requires detailed studies on habitat selection and spatial distribution. Although small pelagic fish aggregate in large shoals and usually exhibit important spatial structure, their dynamics in time and space remain unpredictable and challenging. In the Gulf of Lions (north-western Mediterranean), sardine and anchovy biomasses have declined over the past 5 years causing an important fishery crisis while sprat abundance rose. Applying geostatistical tools on scientific acoustic surveys conducted in the Gulf of Lions, we investigated anchovy, sardine and sprat spatial distributions and structures over 10 years. Our results show that sardines and sprats were more coastal than... |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00226/33739/32151.pdf |
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| Morfin, Marie; Fromentin, Jean-marc; Jadaud, Angelique; Bez, Nicolas. |
| This study analyzes the temporal variability/stability of the spatial distributions of key exploited species in the Gulf of Lions (Northwestern Mediterranean Sea). To do so, we analyzed data from the MEDITS bottom-trawl scientific surveys from 1994 to 2010 at 66 fixed stations and selected 12 key exploited species. We proposed a geostatistical approach to handle zero-inflated and non-stationary distributions and to test for the temporal stability of the spatial structures. Empirical Orthogonal Functions and other descriptors were then applied to investigate the temporal persistence and the characteristics of the spatial patterns. The spatial structure of the distribution (i.e. the pattern of spatial autocorrelation) of the 12 key species studied remained... |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00087/19860/17507.pdf |
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| Registros recuperados: 20 | |
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