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| Registros recuperados: 28 | |
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| Woillez, Mathieu; Fablet, Ronan; Tran-thanh Ngo,; Lalire, Maxime; Lazure, Pascal; De Pontual, Helene. |
| Numerous methods have been developed to geolocate fish from data storage tags. Whereas demersal species have been tracked using tide-driven geolocation models, pelagic species which undertake extensive migrations have been mainly tracked using light-based models. Here, we present a new HMM-based model that infers pelagic fish positions from the sole use of high-resolution temperature and depth histories. A key contribution of our framework lies in model parameter inference (diffusion coefficient and noise parameters with respect to the reference geophysical fields—satellite SST and temperatures derived from the MARS3D hydrodynamic model), which improves model robustness. As a case study, we consider long time series of data storage tags (DSTs) deployed on... |
| Tipo: Text |
Palavras-chave: Fish movement; Archival tagging; Migration; Population structure; Hidden Markov Model (HMM); State-space model. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00300/41097/40270.pdf |
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| Gloaguen, Pierre; Mahevas, Stephanie; Rivot, Etienne; Woillez, Mathieu; Guitton, Jerome; Vermard, Youen; Etienne, Marie-pierre. |
| The understanding of the dynamics of fishing vessels is of great interest to characterize the spatial distribution of the fishing effort and to define sustainable fishing strategies. It is also a prerequisite for anticipating changes in fishermen's activity in reaction to management rules, economic context, or evolution of exploited resources. Analyzing the trajectories of individual vessels offers promising perspectives to describe the activity during fishing trips. A hidden Markov model with two behavioral states (steaming and fishing) is developed to infer the sequence of non-observed fishing vessel behavior along the vessel trajectory based on Global Positioning System (GPS) records. Conditionally to the behavior, vessel velocity is modeled with an... |
| Tipo: Text |
Palavras-chave: Hidden Markov model; Vessels dynamics; RECOPESCA; Autoregressive process; Baum-Welch algorithm. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00179/29049/27485.pdf |
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| Petitgas, Pierre; Renard, Didier; Desassis, Nicolas; Huret, Martin; Romagnan, Jean-baptiste; Doray, Mathieu; Woillez, Mathieu; Rivoirard, Jacques. |
| This paper presents a novel application of the geostatistical multivariate method known as min–max autocorrelation factors (MAFs) for analysing fisheries survey data in a space–time context. The method was used to map essential fish habitats and evaluate the variability in time of their occupancy. Research surveys at sea on marine fish stocks have been undertaken for several decades now. The data are time series of yearly maps of fish density, making it possible to analyse the space–time variability in fish spatial distributions. Space–time models are key to addressing conservation issues requiring the characterization of variability in habitat maps over time. Here, the variability in fisheries survey data series is decomposed in space and time to address... |
| Tipo: Text |
Palavras-chave: MAF; Space-time; Habitat; Mapping; Sardine; Bay of Biscay. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00599/71157/69915.pdf |
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| Boyd, Charlotte; Woillez, Mathieu; Bertrand, Sophie; Castillo, Ramiro; Bertrand, Arnaud; Punt, Andre E.. |
| Small pelagic fish aggregate within areas of suitable habitat to form patchy distributions with localized peaks in abundance. This presents challenges for geostatistical methods designed to investigate the processes underpinning the spatial distribution of stocks and simulate distributions for further analysis. In two-stage models, presence/absence is treated as separable and independent from the process explaining non-zero densities. This is appropriate where gaps in the distribution are attributable to one process and conditional abundance to another, but less so where patchiness is attributable primarily to the strong schooling tendencies of small pelagic fish within suitable habitat. We therefore developed a new modelling framework based on a truncated... |
| Tipo: Text |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00222/33367/31773.pdf |
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| Dambrine, Chloe; Woillez, Mathieu; Huret, Martin; De Pontual, Helene. |
| Fish habitats sustain essential functions for fish to complete their life cycle, such as feeding, growing and spawning. Conservation is crucial to maintain fish populations and their exploitation. Since 2013, the spawning stock biomass of the northern stock of European seabass (Dicentrarchus labrax) has been in a worrying state. A series of low recruitments with a persistently high level of fishing has been blamed, raising concerns about the processes involved in seabass reproduction and settlement in nurseries. Here, we characterise seabass spawning areas along the French Atlantic coast using vessel monitoring system (VMS) data. A non‐linear geostatistical approach was applied, from 2008 to 2014, to detect locations where seabass aggregate for spawning.... |
| Tipo: Text |
Palavras-chave: Bay of Biscay; Bayesian spatio‐temporal modelling; Dicentrarchus labrax; English Channel; European sea bass; Non‐linear geostatistics; Spawning grounds. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00668/77997/80218.pdf |
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| Morato, Telmo; González‐irusta, José‐manuel; Dominguez‐carrió, Carlos; Wei, Chih‐lin; Davies, Andrew; Sweetman, Andrew K.; Taranto, Gerald H.; Beazley, Lindsay; García‐alegre, Ana; Grehan, Anthony; Laffargue, Pascal; Murillo, Francisco Javier; Sacau, Mar; Vaz, Sandrine; Kenchington, Ellen; Arnaud-haond, Sophie; Callery, Oisín; Chimienti, Giovanni; Cordes, Erik; Egilsdottir, Hronn; Freiwald, André; Gasbarro, Ryan; Gutiérrez‐zárate, Cristina; Gianni, Matthew; Gilkinson, Kent; Wareham Hayes, Vonda E.; Hebbeln, Dierk; Hedges, Kevin; Henry, Lea‐anne; Johnson, David; Koen‐alonso, Mariano; Lirette, Cam; Mastrototaro, Francesco; Menot, Lenaick; Molodtsova, Tina; Durán Muñoz, Pablo; Orejas, Covadonga; Pennino, Maria Grazia; Puerta, Patricia; Ragnarsson, Stefán Á.; Ramiro‐sánchez, Berta; Rice, Jake; Rivera, Jesús; Roberts, J. Murray; Ross, Steve W.; Rueda, José L.; Sampaio, Íris; Snelgrove, Paul; Stirling, David; Treble, Margaret A.; Urra, Javier; Vad, Johanne; Oevelen, Dick; Watling, Les; Walkusz, Wojciech; Wienberg, Claudia; Woillez, Mathieu; Levin, Lisa A.; Carreiro‐silva, Marina. |
| The deep sea plays a critical role in global climate regulation through uptake and storage of heat and carbon dioxide. However, this regulating service causes warming, acidification and deoxygenation of deep waters, leading to decreased food availability at the seafloor. These changes and their projections are likely to affect productivity, biodiversity and distributions of deep‐sea fauna, thereby compromising key ecosystem services. Understanding how climate change can lead to shifts in deep‐sea species distributions is critically important in developing management measures. We used environmental niche modelling along with the best available species occurrence data and environmental parameters to model habitat suitability for key cold‐water coral and... |
| Tipo: Text |
Palavras-chave: Climate change; Cold-water corals; Deep-sea; Fisheries; Fishes; Habitat suitability modelling; Octocorals; Scleractinians; Species distribution models; Vulnerable marine ecosystems. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00610/72211/71007.pdf |
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| Hinckley, Sarah; Parada, Carolina; Horne, John K.; Mazur, Michael; Woillez, Mathieu. |
| Biophysical individual-based models (IBMs) have been used to study aspects of early life history of marine fishes such as recruitment, connectivity of spawning and nursery areas, and marine reserve design. However, there is no consistent approach to validating the spatial outputs of these models. In this study, we hope to rectify this gap. We document additions to an existing individual-based biophysical model for Alaska walleye pollock (Gadus chalcogrammus), some simulations made with this model and methods that were used to describe and compare spatial output of the model versus field data derived from ichthyoplankton surveys in the Gulf of Alaska. We used visual methods (e.g. distributional centroids with directional ellipses), several indices (such as... |
| Tipo: Text |
Palavras-chave: Mathematical models; Statistical analysis; Marine fish; Spatial distributions; Spatial analysis; Individual-based models; USA gulf of alaska; Walleye pollock. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00327/43775/43332.pdf |
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| Dambrine, Chloe; Huret, Martin; Woillez, Mathieu; Pecquerie, Laure; Allal, Francois; Servili, Arianna; De Pontual, Helene. |
| The European seabass (Dicentrarchus labrax) is a species of particular ecological and economic importance. Stock assessments have recently revealed the worrying state of the “Northern stock”, probably due to overfishing and a series of poor recruitments. The extent to which these poor recruitments are due to environmental variability is difficult to assess, as the processes driving the seabass life cycle are poorly known. Here we investigate how food availability and temperature may affect the growth and survival of wild seabass at the individual scale. To this end, we developed a bioenergetics model based on the Dynamic Energy Budget (DEB) theory. We applied it to seabass population of the Northeast Atlantic region (Bay of Biscay – English Channel area)... |
| Tipo: Text |
Palavras-chave: Dicentrarchus labrax Northeast Atlantic Dynamic Energy Budget theory Growth; Starvation Early-life stages. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00612/72397/71341.pdf |
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| Heerah, Karine; Woillez, Mathieu; Fablet, Ronan; Garren, Francois; Martin, Stephane; De Pontual, Helene. |
| Background Movement pattern variations are reflective of behavioural switches, likely associated with different life history traits in response to the animals’ abiotic and biotic environment. Detecting these can provide rich information on the underlying processes driving animal movement patterns. However, extracting these signals from movement time series, requires tools that objectively extract, describe and quantify these behaviours. The inference of behavioural modes from movement patterns has been mainly addressed through hidden Markov models. Until now, the metrics implemented in these models did not allow to characterize cyclic patterns directly from the raw time series. To address these challenges, we developed an approach to i) extract new metrics... |
| Tipo: Text |
Palavras-chave: Fourier transform; Non negative matrix factorization; Classification; Animal behaviour; European sea bass; Movement ecology; Diurnal and tidal cycles; Biologging; Data storage tags. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00402/51400/51974.pdf |
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| Huret, Martin; Petitgas, Pierre; Woillez, Mathieu. |
| Dispersal of fish early life stages explains part of the recruitment success, through interannual variability in spawning, transport and survival. Dispersal results from a complex interaction between physical and biological processes acting at different temporal and spatial scales, and at the individual or population level. In this paper we quantify the response of anchovy egg and larval dispersal in the Bay of Biscay to the following sources of variability: vertical larval behaviour, drift duration, adult spawning location and timing, and spatio-temporal variability in the hydrodynamics. We use simulations of Lagrangian trajectories in a 3-dimensional hydrodynamic model, as well as spatial indices describing different properties of the dispersal kernel:... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00024/13544/10577.pdf |
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| Woillez, Mathieu; Rivoirard, Jacques; Fernandes, Paul G.. |
| Geostatistical simulations, which can reproduce the spatial variability of a variable, are particularly helpful in estimating the uncertainty associated with the combination of different sources of variability. Acoustic surveys offer an example of such complex situations, where different data (e.g. acoustic backscatter, fish length, and fish age) must be combined to estimate abundance and its associated uncertainty. In this paper, the uncertainty of Scottish herring acoustic-survey estimates is investigated using these techniques. A specific multivariate, geostatistical model is used to describe the structural relationships, which includes highly skewed distributions of the acoustic-backscatter data and incorporates relationships between depth, mean... |
| Tipo: Text |
Palavras-chave: Scottish herring; Geostatistics; Conditional simulations; Acoustic survey. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6760.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... |
| Tipo: Text |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00585/69732/67621.pdf |
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| Petitgas, Pierre; Woillez, Mathieu; Doray, Mathieu; Rivoirard, Jacques. |
| Marine research survey data on fish stocks often show a small proportion of very high-density values, as for many environmental data. This makes the estimation of second-order statistics, such as the variance and the variogram, non-robust. The high fish density values are generated by fish aggregative behaviour, which may vary greatly at small scale in time and space. The high values are thus imprecisely known, both in their spatial occurrence and order of magnitude. To map such data, three indicator-based geostatistical methods were considered, the top-cut model, min–max autocorrelation factors (MAF) of indicators, and multiple indicator kriging. In the top-cut and MAF approaches, the variable is decomposed into components and the most continuous ones... |
| Tipo: Text |
Palavras-chave: Top-cut; MAF; Indicators; Co-kriging; Skewed distribution; Anchovy; Bay of Biscay; Fisheries survey data; Aggregation. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00429/54021/55339.pdf |
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| Barra, Marco; Petitgas, Pierre; Bonanno, Angelo; Somarakis, Stylianos; Woillez, Mathieu; Machias, Athanasios; Mazzola, Salvatore; Basilone, Gualtiero; Giannoulaki, Marianna. |
| Geostatistical techniques were applied and a series of spatial indicators were calculated (occupation, aggregation, location, dispersion, spatial autocorrelation and overlap) to characterize the spatial distributions of European anchovy and sardine during summer. Two ecosystems were compared for this purpose, both located in the Mediterranean Sea: the Strait of Sicily (upwelling area) and the North Aegean Sea (continental shelf area, influenced by freshwater). Although the biomass of anchovy and sardine presented high interannual variability in both areas, the location of the centres of gravity and the main spatial patches of their populations were very similar between years. The size of the patches representing the dominant part of the abundance (80%) was... |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00276/38758/37299.pdf |
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| Marchal, Paul; Bartelings, Heleen; Bastardie, François; Batsleer, Jurgen; Delaney, Alyne; Girardin, Raphael; Gloaguen, Pierre; Hamon, Katell; Hoefnagel, Ellen; Jouanneau, Charlène; Mahevas, Stephanie; Nielsen, Rasmus; Piwowarczyk, Joanna; Poos, Jan-jaap; Schulze, Torsten; Rivot, Etienne; Simons, Sarah; Tidd, Alex; Vermard, Youen; Woillez, Mathieu. |
| The scope of this report is to present the science developed within the VECTORS project to improve the understanding of the key processes driving the behaviour of human agents utilising a variety of EU maritime domains. While particular attention has been paid to the spatial interactions between fishing activities and other human uses (e.g., maritime traffic, offshore wind parks, aggregate extractions), the behaviour of non-fishing sectors of activity has also been considered. Various quantitative and semi-qualitative approaches have been pursued to gain better insight into behavioural drivers based on past data, and also forecast how human agents would react if access was constrained by either management (e.g. Marine Protected Areas – MPA), or the... |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00223/33377/31802.pdf |
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| Registros recuperados: 28 | |
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