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Registros recuperados: 29
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Analysing multiple time series and extending significance testing in wavelet analysis ArchiMer
Rouyer, Tristan; Fromentin, Jean-marc; Stenseth, N; Cazelles, B.
In nature, non-stationarity is rather typical, but the number of statistical tools allowing for non-stationarity remains rather limited. Wavelet analysis is such a tool allowing for non-stationarity but the lack of an appropriate test for statistical inference as well as the difficulty to deal with multiple time series are 2 important shortcomings that limits its use in ecology. We present 2 approaches to deal with these shortcomings. First, we used 1/f beta models to test cycles in the wavelet spectrum against a null hypothesis that takes into account the highly autocorrelated nature of ecological time series. To illustrate the approach, we investigated the fluctuations in bluefin tuna trap catches with a set of different null models. The 1/f beta models...
Tipo: Text Palavras-chave: Maximum covariance analysis; Surrogates; Wavelet significance testing; Wavelet clustering; Multivariate time series; Non stationarity.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-4291.pdf
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Analytical study of on-chip generations of analog sine-wave based on combined digital signals ArchiMer
David-grignot, Stephane; Lamlih, Achraf; Kerzerho, Vincent; Azaıs, Florence; Soulier, Fabien; Bernard, Serge; Rouyer, Tristan; Bonhommeau, Sylvain.
On-chip sine-wave signal generation is widely covered by literature for Built-In-Self Test (BIST) or biosensor applications. The objective is to generate pure and robust sinewave signal with minimal hardware resources. An attractive solution consists in combining several digital signals to built this analog sine-wave. The objective of this paper is to give an analytical study of various potential solutions based on digitalbased approaches. Thanks to this study, we prove that technique consisting in setting the phase shifts and various amplitude values of the square-wave signals is the most efficient approach. Moreover, this study allows the selection of the best solution in terms of parameters of the square-wave signals to cancel loworder harmonics of the...
Tipo: Text Palavras-chave: Harmonic cancellation; Sine-wave generation; On-chip signal generation.
Ano: 2017 URL: https://archimer.ifremer.fr/doc/00395/50608/55366.pdf
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Assessing causal links in fish stock–recruitment relationships ArchiMer
Pierre, Maud; Rouyer, Tristan; Bonhommeau, Sylvain; Fromentin, Jean-marc.
Understanding whether recruitment fluctuations in fish stock arise from stochastic forcing (e.g. environmental variations) rather than deterministic forces (e.g. intrinsic dynamics) is a long standing question with important applied consequences for fisheries ecology. In particular, the relationship between recruitment, spawning stock biomass and environmental factors is still poorly understood, even though this aspect is crucial for fisheries management. Fisheries data are often short, but arise from complex dynamical systems with a high degree of stochastic forcing, which are difficult to capture through classic modelling approaches. In the present study, recent statistical approaches based on the approximation of the attractors of dynamical systems are...
Tipo: Text Palavras-chave: Causality; Forecasting models; Marine.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00408/51930/52555.pdf
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Attempts to tag large Atlantic bluefin tuna: Development of a methododolgy for future large scale deployments in the Mediterranean ArchiMer
Rouyer, Tristan; Bonhommeau, Sylvain; Giordano, F; Wendling, B; Ellul, S; Ellul, G; Psaila, Ma; Deguara, S; Bernard, S; Kerzerho, V.
Tipo: Text Palavras-chave: Large atlantic bluefin tuna; Mediterranean; Malta; Electronic tagging; Farming cages; Purse seiners.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00484/59609/62626.pdf
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Combined effects of exploitation and temperature on fish stocks in the Northeast Atlantic ArchiMer
Rouyer, Tristan; Fromentin, Jean-marc; Hidalgo, Manuel; Stenseth, Nils C..
Fish stock fluctuations are affected by two potentially confounding forces: the removal of individuals by fisheries and climatic variations affecting the productivity of fish populations. Disentangling the relative importance of these forces has thus been a question of primary importance for fisheries management and conservation. Through the analysis of long-term time-series for 27 fish stocks from the Northeast Atlantic, the present study shows that the sign and intensity of the effect of temperature on biomass are dependent on the geographical location: the stocks located at the southernmost and northernmost latitudes of our study displayed stronger associations with temperature than the stocks located in the middle range of latitudes. As a consequence,...
Tipo: Text Palavras-chave: Combined climate/exploitation effect; Exploitation; Fish stocks; Northeast Atlantic; Response to climate; Time-series.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00230/34107/32821.pdf
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Complex interplays among population dynamics, environmental forcing, and exploitation in fisheries ArchiMer
Rouyer, Tristan; Fromentin, Jean-marc; Menard, Felix; Calzelles, B; Briand, K; Pianet, R; Planque, Benjamin; Stenseth, N.
The patterns of variations in fisheries time series are known to result from a complex combination of species and fisheries dynamics all coupled with environmental forcing (including climate, trophic interactions, etc.). Disentangling the relative effects of these factors has been a major goal of fisheries science for both conceptual and management reasons. By examining the variability of 169 tuna and billfish time series of catch and catch per unit effort (CPUE) throughout the Atlantic as well as their linkage to the North Atlantic Oscillation (NAO), we find that the importance of these factors differed according to the spatial scale. At the scale of the entire Atlantic the patterns of variations are primarily spatially structured, whereas at a more...
Tipo: Text Palavras-chave: Time series analysis; North Atlantic Oscillation; Atlantic tuna.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-3984.pdf
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Context-dependent interplays between truncated demographies and climate variation shape the population growth rate of a harvested species ArchiMer
Hidalgo, Manuel; Rouyer, Tristan; Bartolino, Valerio; Cervino, Santiago; Ciannelli, Lorenzo; Massuti, Enric; Jadaud, Angelique; Saborido-rey, Fran; Durant, Joel M.; Santurtun, Marina; Pineiro, Carmen; Stenseth, Nils C..
Fisheries ecologists traditionally aimed at disentangling climate and fishing effects from the population dynamics of exploited marine fish stocks. However, recent studies have shown that internal characteristics and external forcing (climate and exploitation) have interactive rather than additive effects. Thought most of these studies explored how demographic truncation induced by exploitation affected the response of recruitment to climate, identifying a general pattern revealed to be difficult as interactions are often case-specific. Here we compared five exploited stocks of European hake Merluccius merluccius from the Atlantic Ocean and Mediterranean Sea to investigate how the interaction between internal characteristics and external forces affect the...
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Ano: 2012 URL: http://archimer.ifremer.fr/doc/00079/19008/17561.pdf
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Density-Dependence in Space and Time: Opposite Synchronous Variations in Population Distribution and Body Condition in the Baltic Sea Sprat (Sprattus sprattus) over Three Decades ArchiMer
Casini, Michele; Rouyer, Tristan; Bartolino, Valerio; Larson, Niklas; Grygiel, Wlodzimierz.
Spatio-temporal density-dependent processes are crucial regulatory factors for natural populations. However, there is a lack of studies addressing spatial density-dependence in fish growth. A previous investigation has suggested spatio-temporal density-dependence in body condition of Baltic sprat. Here, we used different techniques, such as centre of gravity, distance, and homogeneity indices, to better characterize the spatial and temporal variations in sprat density and body condition in the Baltic Proper. Our results evidenced a negative spatio-temporal co-variation between the centres of gravity of density and maximum condition. In the 1980s-early 1990s both centres were located in the middle of the Baltic Proper. From the mid 1990s the centres...
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Ano: 2014 URL: http://archimer.ifremer.fr/doc/00190/30091/28745.pdf
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Effects of extraction method and storage of dry tissue on marine lipids and fatty acids ArchiMer
Sardenne, Fany; Bodin, Nathalie; Metral, Luisa; Crottier, Anais; Le Grand, Fabienne; Bideau, Antoine; Brisset, Blandine; Bourjea, Jerome; Saraux, Claire; Bonhommeau, Sylvain; Kerzerho, Vincent; Bernard, Serge; Rouyer, Tristan.
Various protocols are currently used to study marine lipids, but there is a growing interest in working on dry samples that are easier to transport. However, reference protocols are still lacking for dry samples. In order to make recommendations on this use, lipid classes and fatty acids (FA) obtained from six analytical protocols using two different tissue states (dry vs wet) and three extraction methods (automat vs manual potter vs leaving the solvent to work on tissue) were compared. Three dry storage modes of tissue (freezer vs gas nitrogen vs dry room) during one and three months were also compared. These comparisons were made on seven marine species with different lipid profiles, including fishes, crustaceans and mollusks. Lipid classes and FA...
Tipo: Text Palavras-chave: Degradation; Freeze-drying; Lyophilization; Lipid class; Marine animal; Protocol.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00467/57898/60189.pdf
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Environmental noise affects the fluctuations of Atlantic large pelagics ArchiMer
Rouyer, Tristan; Fromentin, Jean-marc; Stenseth, Nils Chr..
Environmental variables affect many processes of fish biology and their fluctuations are thought to be one of the main factors in variability of fish stocks. Recent work has shown that the variability of the environment in the frequency domain (i.e., the environmental noise) can interact with endogenous processes (e.g., density dependence) and affect fluctuations of animal populations. In this study, we investigate whether fluctuations of large pelagics' time series are affected by environmental noise and whether life-history traits of species modulate this response. By analysing several environmental variables and a large dataset of tuna and billfish catch per unit effort (CPUE) time series from the Atlantic, we show that in environments dominated by...
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Ano: 2010 URL: http://archimer.ifremer.fr/doc/00011/12230/9083.pdf
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Gestion écosystémique de la pêche et de l’aquaculture. La gestion du thon rouge : histoire de la surexploitation et de son rétablissement ArchiMer
Fromentin, Jean-marc; Rouyer, Tristan.
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Ano: 2019 URL: https://archimer.ifremer.fr/doc/00487/59824/62967.pdf
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Implications de la couleur du bruit environnemental sur la variabilité des stocks halieutiques exploités ArchiMer
Rouyer, Tristan.
The origin of fish stocks variability is a key question in fisheries science. The exploitation indeed has an important effect in terms of biomass reduction, but environmental forcing is of central interest as it affects numerous key biological processes. Recent theoretical results have shown that the nature of the environmental fluctuations, the environmental noise, has important ecological consequences on populations and particularly on their fluctuations. In addition the effects of exploitation, that are not a simple removal of individuals but also profoundly modifies the demography, the structure and the trophic interactions of fish stocks, can interact with environmental effects. Through an extensive analysis of time series we aim at understanding the...
Tipo: Text Palavras-chave: Fisheries; Life history traits; Fish stocks variability; Environmental noise; Wavelets; Time series; Pêche; Traits d'histoire de vie; Variabilité des stocks halieutiques; Couleur du bruit environnemental; Ondelettes; Séries temporelles.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/these-6596.pdf
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Investigating trophic-level variability in Celtic Sea fish predators ArchiMer
Chassot, E; Rouyer, Tristan; Trenkel, Verena; Gascuel, D.
The trophic level mean and variance, and the degree of omnivory for five Celtic Sea fish predators were estimated using a database of stomach content records characterized by a high level of taxonomic resolution. The predators occupied a high position in the food web, i.e. 4.75 for Atlantic cod Gadus morhua, 444 for haddock Melanogrammus aeglefinus, 4.88 for European hake Merluccius merluccius, 5.00 for megrim Lepidorhombus whiffiagonis and 5.27 for whiting Merlangius merlangus. The level of taxonomic resolution of the prey did not greatly affect mean T-L predator values; an effect on variance was evident, low resolution masking intra-population variability in T-L. Generalized additive models (GAM) were used to explain the variability of predator T-L...
Tipo: Text Palavras-chave: Trophic level; Predation; Omnivory; Indicator; GAM; Food web.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-4699.pdf
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La force de l’observation pérenne, la synergie de l’intégration numérique. Suivi des populations halieutiques et de mammifères marins du golfe du Lion ArchiMer
Jadaud, Angelique; Saraux, Claire; Rouyer, Tristan.
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Ano: 2019 URL: https://archimer.ifremer.fr/doc/00487/59829/62972.pdf
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On-chip Generation of Sine-wave Summing Digital Signals: an Analytic Study Considering Implementation Constraints ArchiMer
David-grignot, Stephane; Lamlih, Achraf; Belhaj, Mohamed Moez; Kerzerho, Vincent; Azais, Florence; Soulier, Fabien; Freitas, Philippe; Rouyer, Tristan; Bonhommeau, Sylvain; Bernard, Serge.
In the context of biosensor as much as Built-In-Self Test (BIST), on-chip sine-wave signal generation is a recurring research topic. Considering the implementation constraints, it implies a trade-off between the amount of resources and the signal quality. An attractive solution consists in combining several digital signals to build this analog sine-wave. The objective of this paper is to give an analytic study of various potential digital-based solutions. Thanks to this study, we prove that the technique consisting in setting the phase shifts and various amplitude values of the square-wave signals is the most efficient approach. This study allows the selection of the optimal square-wave signal parameters to cancel low-order harmonics of the generated...
Tipo: Text Palavras-chave: Harmonic cancelation; Sine-wave generation; On-chip signal generation.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00425/53678/54609.pdf
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Online collaborative environment to run Stock Assessment work ow: an option for IOTC? ArchiMer
Imzilen, Taha; Bonhommeau, Sylvain; Rouyer, Tristan; Kell, Laurence T; Chassot, Emmanuel; Barde, Julien.
In this note, we present an approach which has been recently used to execute online the set of codes used for eastern blue_n tuna (BFT-E) stock assessment at ICCAT. We aim at discussing the possible interest of the approach to the IOTC Community for focusing on Indian ocean tuna and tuna-like stocks and running other assesment models such as Stock Synthesis 3 (SS3). In 2014, ICCAT BFT-E working group has been able to execute thousands of model runs by using parallelization of R and Fortran codes on a supercomputer. This approach has a lot of scienti_c bene_ts, in particular for better including the multiple sources of uncertainty in assessment results and associated scienti_c advice. However, very few participants would be able to reproduce it without...
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Ano: 2016 URL: http://archimer.ifremer.fr/doc/00360/47135/47084.pdf
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Online collaborative environment to run the eastern bluefin tuna stock assessment workflow ArchiMer
Imzilen, Taha; Bonhommeau, Sylvain; Rouyer, Tristan; Kell, Laurence T; Barde, Julien.
In this note, we describe an approach which makes possible to execute online the set of codes used for eastern bluefin tuna (BFT-E) stock assess-ment at ICCAT. In 2014, ICCAT BFT-E working group has been able to execute thousands of model runs by using parallelization of R and Fortran codes on a supercomputer. This new approach has a lot of scientific benefits, but very few participants would be able to reproduce it without specific skills. Since november 2015, the H2020 BlueBridge project is funding an engineer to set up a WebSite (or VRE for Virtual Research Environment) where users will be able to parametrize and execute various steps of the BFT-E stock assessment workflow. By repackaging codes provided by ICCAT BFT-E working group the same codes are...
Tipo: Text Palavras-chave: Bluefin tuna; Scientific cloud; Stock assessment; Grid computing; Online processing.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00403/51471/52042.pdf
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Patterns of variations in large pelagic fish: A comparative approach between the Indian and the Atlantic Oceans ArchiMer
Corbineau, A.; Rouyer, Tristan; Fromentin, Jean-marc; Cazelles, B.; Fonteneau, Alain; Menard, Frederic.
Catch data of large pelagic fish such as tuna, swordfish and billfish are highly variable ranging from short to long term. Based on fisheries data, these time series are noisy and reflect mixed information on exploitation (targeting, strategy, fishing power), population dynamics (recruitment, growth, mortality, migration, etc.), and environmental forcing (local conditions or dominant climate patterns). In this work, we investigated patterns of variation of large pelagic fish (i.e. yellowfin tuna, bigeye tuna, swordfish and blue marlin) in Japanese longliners catch data from 1960 to 2004. We performed wavelet analyses on the yearly time series of each fish species in each biogeographic province of the tropical Indian and Atlantic Oceans. In addition, we...
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Ano: 2010 URL: http://archimer.ifremer.fr/doc/00011/12231/9029.pdf
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POPSTAR : une nouvelle génération de système de marquage pour le suivi des espèces marines ArchiMer
Bernard, S; Kerzérho, V; Rouyer, Tristan; Bonhommeau, Sylvain.
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Ano: 2019 URL: https://archimer.ifremer.fr/doc/00487/59830/62973.pdf
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Potential further considerations on the conditioning of operating models of Atlantic Bluefin Tuna ArchiMer
Kimoto, A; Walter, Jf; Sharma, R; Rouyer, Tristan.
ICCAT BFTWG completed the stock assessment using multiple stock assessment methods in 2017, and they are going to proceed with the MSE process: development of MP in 2018. It is well recognized that the performance results of MPs often depend on the design of the OM and its conditioning that capture the range of potential population dynamics. It is therefore critical to consider them carefully before moving to the development of MP, but this has been a monumental task given the complexity of ABFT. The ICCAT GBYP Core modelling group has developed the OM by incorporating the mixing between two stocks, and the trial specifications. However, the 2017 stock assessment raised a number of issues that may require further consideration for the OMs, particularly...
Tipo: Text Palavras-chave: Bluefin tuna; Conditioning; Operating model; Uncertainty; Management procedure; MSE.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00484/59607/62624.pdf
Registros recuperados: 29
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