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A model for the phenotypic plasticity of North sea herring growth in relation to trophic conditions ArchiMer
Shinn, Yunne-jai; Rochet, Marie-joelle.
An adaptation of the von Bertalanffy growth model is formulated to describe the phenotypic plasticity of fish somatic growth in relation to trophic conditions. The model is developed for the North sea Downs herring (Clupea harengus). II suggests that annual growth variability during 1974-1990 was mainly due to the combined effects of herring abundance and wind-induced turbulence (coincident with the spring stratification of the water column). Springtime turbulences cause reduced and delayed planktonic blooms preceding the annual foraging period of Downs herring. The negative relation observed between herring abundance and growth is hypothesized to be due to intra-specific competition for trophic resources. Incorporated into the calculation of yield per...
Tipo: Text Palavras-chave: Modèle de croissance; Densité-dépendance; Plasticité phénotypique; Clupea harengus; Hareng de mer du Nord; Gestion des pêches; Growth model; Density dependence; Phenotypic plasticity; Fishery management; Clupea harengus; North sea herring.
Ano: 1998 URL: http://archimer.ifremer.fr/doc/00188/29878/28358.pdf
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Contribution à l'étude de la dynamique du thon rouge Atlantique - Approches écologiques et océanographiques ArchiMer
Royer, Francois.
[1] The spatial and temporal dynamics of Atlantic bluefin tuna, Thunnus thynnus, are here investigated through data analysis and statistical modelling. The local, regional and global scales are considered successively. A phenomenological approach is favoured, as well the extended use of image processing tools and estimation theory techniques. Their potential role in partially observed or ill-defined problems in marine ecology is presented and discussed. The acute need for frequency-explicit methods is in particular stressed out. Hypothesis testing and significance testing of ecological space/time processes are further discussed. [2] The first chapter depicts how surface fronts can structure the pelagic habitat: dedicated detection and mapping tools are...
Tipo: Text Palavras-chave: Archival tags; Kalman filter; Density dependence; Oceanic fronts; Time series; Thunnus thynnus; Marques archives; Filtre de Kalman; Densite dependence; Fronts oceaniques; Series temporelles; Thunnus thynnus.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/2005/these-636.pdf
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Does the concept of spawning per recruit make sense? ArchiMer
Rochet, Marie-joelle.
Density dependence means that exploited fish populations exhibit earlier maturity, a faster growth rate, increased fecundity and reduced egg size. Here, the consequences of these effects on population dynamics, the estimation of spawning biomass per recruit and associated biological reference points are examined by a simulation model. The model is a self-regenerating model in which the population parameters (age at maturity, growth, fecundity, egg size) vary according to three classes of population abundance. Early life stages are characterized by a size-dependent growth and mortality model. It is concluded that spawning per recruit is an ambiguous concept because, if density dependence occurs in the adult population, the spawning biomass of a cohort is...
Tipo: Text Palavras-chave: Teleost fishes; Population dynamics; Life history; Density dependence; Biological reference points.
Ano: 2000 URL: http://archimer.ifremer.fr/doc/2000/publication-485.pdf
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Impact of Environmental Covariation in Growth and Mortality on Evolving Maturation Reaction Norms ArchiMer
Marty, Lise; Dieckmann, Ulf; Rochet, Marie-joelle; Ernande, Bruno.
Maturation age and size have important fitness consequences through their effects on survival probabilities and body sizes. The evolution of maturation reaction norms in response to environmental covariation in growth and mortality is therefore a key subject of life-history theory. The eco-evolutionary model we present and analyze here incorporates critical features that earlier studies of evolving maturation reaction norms have often neglected: the trade-off between growth and reproduction, source-sink population structure, and population regulation through density-dependent growth and fecundity. We report the following findings. First, the evolutionarily optimal age at maturation can be decomposed into the sum of a density-dependent and a...
Tipo: Text Palavras-chave: Phenotypic plasticity; Growth-reproduction trade-off; Source-sink population structure; Density dependence; Selection gradient.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00035/14607/11988.pdf
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Introduced herbivores and the Allee effect in animal-pollinated plants Ecología austral
Vázquez,Diego P.
Interspecific interactions can be modulated by the community context in which they occur. In this paper I focus on plant-pollinator interactions and their modulation by introduced herbivores through changes in plant population density. I first develop a mathematical model that relates the population density of an animal-pollinated plant species with pollinator visitation frequency, pollination, reproduction and per capita growth rate. This model allows me to investigate how several pollination-related parameters -including relative abundance of the focal plant species, pollinator specialization, pollination quantity and quality and pollen limitation of reproduction- influence the relationship between per capita growth rate and population density. I then...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Abundance; Allee effect; Density dependence; Introduced herbivores; Mutualism; Plant reproduction; Pollination; Pollinator specialization and generalization; Population dynamics.
Ano: 2007 URL: http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S1667-782X2007000100003
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Recurrent and density-dependent patterns in long-term fluctuations of Atlantic bluefin tuna trap catches ArchiMer
Royer, Francois; Fromentin, Jean-marc.
We present a methodology for the non-linear analysis of long-term ecological time series. Using a time-delay embedding procedure, we investigated the complexity of 1-dimensional signals and compared their structure to their stochastic counterparts. Recurrence-based statistics and surrogate testing were used for this purpose. The method was first tested on elementary models for illustrative purposes and its potentialities and limits reviewed. We then investigated the time structure of 6 Mediterranean bluefin tuna trap catches known to display long-term fluctuations. These time series showed significantly more determinism than linear stochastic processes, displaying more recurring patterns/states than stochastic surrogates. The short term structure of these...
Tipo: Text Palavras-chave: Embedding; Surrogate testing; Density dependence; Recurrence; Thunnus thynnus.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-1982.pdf
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Regulación denso-dependiente del crecimiento individual de la almeja púrpura (Amiantis purpurata, Lamarck 1818) OceanDocs
Pappalardo, M.P.; Morsan, E.M..
In this study we analyze growth, mortality and estimated biomass trend of purple clam, Amiantis purpurata, population placed in Playa Villarino, (Northern San Matias gulf, Argentina) in the southern most boundary of its geographical distribution. Previously, the population structure was described composed by three consecutive cohorts settled among 1978-1980, and the individual growth rate showed high spatial variability. The hypothesis to test in this study is that growth rate is regulated by local biomass. We choice four sites with different densities, to assess growth rate, natural mortality and retrospective estimated biomass trend. During February 2003, densities and growth rate (using external growth bands measurements) were analyzed matching with a...
Tipo: Journal Contribution Palavras-chave: Growth rate; Clam fisheries; Mortality; Growth curves; Density dependence; Biomass; Growth; Biomass.
Ano: 2005 URL: http://hdl.handle.net/1834/4385
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