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An autoregressive model to describe fishing vessel movement and activity ArchiMer
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: http://archimer.ifremer.fr/doc/00179/29049/27485.pdf
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Effects of Stochasticity in Early Life History on Steepness and Population Growth Rate Estimates: An Illustration on Atlantic Bluefin Tuna ArchiMer
Simon, Maximilien; Fromentin, Jean-marc; Bonhommeau, Sylvain; Gaertner, Daniel; Brodziak, Jon; Etienne, Marie-pierre.
The intrinsic population growth rate (r) of the surplus production function used in the biomass dynamic model and the steepness (h) of the stock-recruitment relationship used in age-structured population dynamics models are two key parameters in fish stock assessment. There is generally insufficient information in the data to estimate these parameters that thus have to be constrained. We developed methods to directly estimate the probability distributions of r and h for the Atlantic bluefin tuna (Thunnus thynnus, Scombridae), using all available biological and ecological information. We examined the existing literature to define appropriate probability distributions of key life history parameters associated with intrinsic growth rate and steepness, paying...
Tipo: Text
Ano: 2012 URL: http://archimer.ifremer.fr/doc/00115/22640/20362.pdf
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Investigating the performances of a bayesian biomass dynamic model with informative priors on Atlantic bluefin tuna ArchiMer
Simon, M; Fromentin, Jean-marc; Bonhommeau, Sylvain; Gaertner, Daniel; Etienne, Marie-pierre.
We examined the possibility of eliciting informative priors for the parameters of a biomass production model with emphasis on the intrinsic population growth rate of Atlantic bluefin tuna (Thunnus thynnus). We reviewed the literature to propose probability distribution functions for the vital rates and used a matrix population model structured by age (Leslie) to compute the population growth rate. A generalized biomass production model is applied on two CPUE and catch datasets (1976-1996 and 1976-2006) using informative priors. The population growth rate prior has a diffuse distribution and is very sensitive to young of the year mortality rate. Thus, we compared the performances of this prior with a commonly used prior for tunas population growth rate. We...
Tipo: Text Palavras-chave: Bayesian model; Population growth rate; Uncertainties; Natural mortality; CPUE; Tuna fisheries; Thunnus thynnus.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00192/30281/28756.pdf
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Metrics for describing dyadic movement: a review ArchiMer
Joo, Rocio; Etienne, Marie-pierre; Bez, Nicolas; Mahevas, Stephanie.
In movement ecology, the few works that have taken collective behaviour into account are data-driven and rely on simplistic theoretical assumptions, relying in metrics that may or may not be measuring what is intended. In the present paper, we focus on pairwise joint-movement behaviour, where individuals move together during at least a segment of their path. We investigate the adequacy of twelve metrics introduced in previous works for assessing joint movement by analysing their theoretical properties and confronting them with contrasting case scenarios. Two criteria are taken into account for review of those metrics: 1) practical use, and 2) dependence on parameters and underlying assumptions. When analysing the similarities between the metrics as...
Tipo: Text Palavras-chave: Collective behaviour; Dyadic movement; Indices; Movement ecology; Spatio-temporal dynamics; Trajectories.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00475/58657/61156.pdf
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Modelling Fishing Vessels Movement and Activity ArchiMer
Gloaguen, Pierre; Mahevas, Stephanie; Rivot, Etienne; Woillez, Mathieu; Guitton, Jérome; Vermard, Youen; Etienne, Marie-pierre.
Tipo: Text
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00371/48181/48296.pdf
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Statistical ecology comes of age ArchiMer
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: http://archimer.ifremer.fr/doc/00249/36026/35298.pdf
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Stochastic differential equation based on a multimodal potential to model movement data in ecology ArchiMer
Gloaguen, Pierre; Etienne, Marie-pierre; Le Corff, Sylvain.
The paper proposes a new model for individuals' movement in ecology. The movement process is defined as a solution to a stochastic differential equation whose drift is the gradient of a multimodal potential surface. This offers a new flexible approach among the popular potential-based movement models in ecology. To perform parameter inference, the widely used Euler method is compared with two other pseudolikelihood procedures and with a Monte Carlo expectation-maximization approach based on exact simulation of diffusions. Performances of all methods are assessed with simulated data and with a data set of fishing vessel trajectories. We show that the usual Euler method performs worse than the other procedures for all sampling schemes.
Tipo: Text Palavras-chave: Exact simulation; Global Positioning System data; Local linearization; Movement model; Pseudolikelihood methods; Stochastic differential equation.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00429/54068/55461.pdf
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