Consulta: creatorFacets:"Petitgas, Pierre"
Registros recuperados: 105
Data/hora: 06/06/2024 10:22:57

Protocole pour la mesure de la densité des oeufs de poissons avec une colonne de densité. Note interne
Provedor de dados: 5
Autores: Petitgas, Pierre.
Protocol established during the 2005 and 2006 Pelgas campaigns, for anchovy eggs in the Bay of Biscay. The density column used is Coombs' (1981). Egg density varies according to surface hydrological conditions (Petitgas et al., 2006), which necessitates a routine measurement of egg density according to a set protocol.
Tipo: Text
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/rapport-6434.pdf

The influence of the environment on the variability of monthly tuna biomass around a moored, fish-aggregating device
Provedor de dados: 5
Autores: Doray, Mathieu; Petitgas, Pierre; Nelson, Laetitia; Mahevas, Stephanie; Josse, E; Reynal, Lionel.
Fish-aggregating devices (FADs) are increasingly used worldwide to enhance tuna catches. Meanwhile, ecosystem-based management of this fishery is constrained by a paucity of information regarding the interaction of FAD-associated tuna aggregations with their local environment. This paper reports the results of a nine-month study around a FAD moored near Martinique Island, aimed at assessing the effects of the local environment on the variability of monthly estimates of proximate tuna biomass. Dual-frequency, active acoustics provided highresolution quantitative data on the pelagic community around the FAD, from fish to micronekton forage. Geostatistics were used to compute biomass estimates of the tuna aggregation comprising most of the FADassociated fish...
Tipo: Text
Palavras-chave: Lesser Antilles; Tuna; Environment; Geostatistics; Biomass estimation; Fish aggregating device.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2008/publication-6162.pdf

Use of satellite image products to understand variation in fish length: Anchovy in the Bay of Biscay
Provedor de dados: 5
Autores: Petitgas, Pierre; Gohin, Francis; Duhamel, Erwan; Doray, Mathieu; Schmidt, Jörn; Voss, Rudiger.
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00590/70202/68229.pdf

Historical fluctuations in spawning location of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) in the Bay of Biscay during 1967-73 and 2000-2004
Provedor de dados: 5
Autores: Bellier, Edwige; Planque, Benjamin; Petitgas, Pierre.
The spatial extent of small pelagic fish spawning habitat is influenced by environmental factors and by the state of the adult population. In return, the configuration of spawning habitat affects recruitment and therefore the future structure of the adult population. Interannual changes in spatial patterns of spawning reflect variations in adult population structures and their environment. The present study describes the historical changes in the spatial distribution of spawning of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) in the Bay of Biscay during two periods: 1967-72 and 2000-2004. Using data from egg surveys conducted in spring, the spatial distributions of anchovy and sardine eggs are characterized by means of geostatistics....
Tipo: Text
Palavras-chave: Spawning habitat; Spatial patterns; Sardine; Long term changes; Bay of Biscay; Anchovy.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-2179.pdf

Une procédure systématique pour le sous-échantillonnage des prélèvements de plancton
Provedor de dados: 5
Autores: Koutsikopoulos, Constantin; Petitgas, Pierre.
It is often necessary to sub-sample plankton samples even if the precision of the estimation is thereby decreased. A methodological optimization is looked for. The variance depends on the procedure of construction of the aliquot (strategy) and the number of individuals counted (effort). The sub-sampling effort is allocated in a general context of repartition of the total effort between sampling and sub-sampling. This effort depends on the time consumed by the sub-sampling procedure, the volume of the aliquot and the number of individuals counted. For the same effort, a systematic procedure for the construction of sub-samples is more precise than a random one because it travels through the entire sample and is thus less dependent on the spatial distribution...
Tipo: Text
Palavras-chave: Plancton; Sous-échantillonnage; Effort; Précision; Plankton; Sub-sampling; Effort; Precision.
Ano: 1990
URL: http://archimer.ifremer.fr/doc/00131/24259/22252.pdf

Direct assessment of anchovy by the Pelgas06 acoustic survey
Provedor de dados: 5
Autores: Masse, Jacques; Mehault, Sonia; Beillois, Pierre; Duhamel, Erwan; Planque, Benjamin; Petitgas, Pierre; Biseau, Alain.
An acoustic survey was carried out in the bay of Biscay from May 1st to May 30th  on board the French research vessel Thalassa. The objective of PELGAS06 survey was to study the abundance and distribution of pelagic fish in the Bay of Biscay. The target species were mainly anchovy and sardine and were considered in a multi-specific context. The results have to be used during ICES working groups in charge of the assessment of sardine, anchovy, mackerel and horse mackerel and in the frame of the Ifremer fisheries ecology program "resources variability"
Tipo: Text
Palavras-chave: Bay of Biscay; Plakton net; Trawl; CUFES; Survey; Acoustic; ICES; PELGAS; Anchovy; Golfe de Gascogne; Filet à plancton; Chalut; CUFES; Campagne; Acoustique; CIEM; PELGAS; Anchois.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/acte-2291.pdf

An individual Based Model of anchovy early life stages in the Bay of Biscay: validation of vertical distribution and growth
Provedor de dados: 5
Autores: Huret, Martin; Petitgas, Pierre; Bourriau, Paul; Grellier, Patrick.
The objective of the study is a better understanding of recruitment variability in anchovy population. An Individual Based Model (IBM) is being developed for the full life cycle of anchovy. The early life stages are presented on this poster. The model is tested in a 1D-vertical framework for validation of the vertical distribution of modelled eggs and larvae against in-situ data. The dynamic Energy Budget (DEB) theory is the biological baseline for individual growth. We test its ability to simulate the observed growth curves between years with contrasted temperatures.
Tipo: Text
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00054/16508/14022.pdf

A geostatistical method for assessing biomass of tuna aggregations around moored fish aggregating devices with star acoustic surveys
Provedor de dados: 5
Autores: Doray, Mathieu; Petitgas, Pierre; Josse, E.
Universal kriging was used to model the spatio-temporal variability in the acoustic density of tuna aggregations recorded during star echosounding surveys around moored fish aggregating devices (FADs) in Martinique (Lesser Antilles). The large-scale deterministic drift in the tuna spatial distribution was modeled using an advection-diffusion equation applied to animal grouping. Residuals from the drift were modeled as a random component with small-scale spatial correlation. An estimation variance formula was derived from this deterministic-statistical mixed model to assess the mean precision of density estimates of daytime tuna aggregation. The mean relative error obtained with our star design for daytime surveys was 24%. The methodology was applied to...
Tipo: Text
Palavras-chave: Acoustic survey precision; Advection diffusion model; Moored fish aggregating devices; Tuna; Geostatistics.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-4559.pdf

Indicator-Based Geostatistical Models For Mapping Fish Survey Data
Provedor de dados: 5
Autores: 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

Effects of spawning patterns and larval mortality on survival to the juvenile stage : a modelling analysis on the anchovy population of the Bay of Biscay
Provedor de dados: 5
Autores: Huret, Martin; Petitgas, Pierre; Struski, Caroline.
Fish populations show complex life cycles with successive dependent life stages, the spatio-temporal patterns of distribution at one stage impacting distribution, growth and mortality during the next stage. Here we propose to assess the relative effect of spawning (timing, duration, fecundity and spatial distribution, resulting from adult environmental conditions over autumn and winter) and larval mortality on the resulting survival at the age of metamorphosis. We used a suite of models run sequentially : a coupled physical-biogeochemical model to provide the environmental forcing, a Dynamic Energy Budget (DEB) model for adult fish growth and reproduction (spawning timing, duration and fecundity), an Individual Based Model (IBM) for larval drift, growth...
Tipo: Text
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00023/13451/10464.pdf

One-dimensional biophysical modelling of fish egg vertical distributions in shelf seas
Provedor de dados: 5
Autores: Petitgas, Pierre; Magri Hoeltzener, Stephanie; Lazure, Pascal.
Modelling the vertical distribution of fish eggs is important when assessing fish stocks with egg production methods and for monitoring the reproductive potential of fish populations. Fish eggs are passive particles and their vertical distribution is determined by a few parameters such as egg density, egg diameter, wind- and tide-induced turbulence, and vertical hydrographic structure. A one-dimensional vertical biophysical, numerical model was developed which was adapted to the hydrography of shelf seas under the influence of tidal currents, wind-induced circulation, and river discharges. The biological part of the model parameterized the ascent velocity of the egg as a function of egg properties (diameter, density) and water properties (density,...
Tipo: Text
Palavras-chave: Vertical distribution; Sprat; Sardine; Fish egg buoyancy; CUFES; Biophysical coupling; Anchovy.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-2277.pdf

A method for controlled target strength measurements of pelagic fish, with application to European anchovy (     Engraulis encrasicolus     )
Provedor de dados: 5
Autores: Doray, Mathieu; Berger, Laurent; Le Bouffant, Naig; Coail, Jean-yves; Vacherot, Jean-philippe; De La Bernardie, Xavier; Moriniere, Pierre; Lys, Elisabeth; Schwab, Romain; Petitgas, Pierre.
Measuring fish target strength (TS) in the wild is challenging because: (i) TS varies versus physical (orientation relative to the incident sound wave, size, and depth) and physiological fish attributes (maturity and condition), (ii) the target species and its aforementioned attributes are difficult to assess in near real time, and (iii) in the case of packed fish schools, accepted echoes may originate from multiple unresolved targets. We propose a method for controlled TS measurements of densely packed small pelagic fish during daytime, based on the joint use of a Remotely Operated Towed Vehicle, “EROC”, with a pelagic trawl fitted with a codend opening system, “ENROL”. EROC, equipped with a 70-kHz split-beam echosounder (Simrad EK60) and a low-light...
Tipo: Text
Palavras-chave: Acoustics; Deformed cylinder model; Engraulis encrasicolus; Remotely operated vehicle; Target strength; Video.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00346/45693/45623.pdf

Using the ALADYM simulation model for exploring the effects of management scenarios on fish population metrics
Provedor de dados: 5
Autores: Spedicato, Maria Teresa; Poulard, Jean-charles; Politou, Chrissi-yianna; Radtke, Krzysztof; Lembo, Giuseppe; Petitgas, Pierre.
Simulation of fisheries systems is a widely used approach that integrates monitoring and assessment tools. We applied the ALADYM (age-length based dynamic model) simulation model to three different studies aimed at investigating correlations between pressure and population metrics, exploring the viability of different mortality levels in long-term scenarios and predicting the effects of combined management measures. Uncertainty was incorporated into the simulations following the Monte Carlo paradigm. Three stocks were used for these exercises: red mullet in the central-southern Tyrrhenian Sea and European hake in both the Bay of Biscay and the Aegean Sea. The analysis of the relationships between total mortality and indicators highlighted significant...
Tipo: Text
Palavras-chave: Simulation model; Model-based indicators; Fishery management; Reference points; Mullus barbatus; Merluccius merluccius; Mediterranean Sea; Atlantic Ocean.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00011/12226/9008.pdf

Anchovy population expansion in the North Sea
Provedor de dados: 5
Autores: Petitgas, Pierre; Alheit, Juergen; Peck, Myron A.; Raab, Kristina; Irigoien, Xabier; Huret, Martin; Van Der Kooij, Jeroen; Pohlmann, Thomas; Wagner, Carola; Zarraonaindia, Iratxe; Dickey-collas, Mark.
The abundance and spatial occupation of European anchovy Engraulis encrasicolus have increased in the North Sea since the mid-1990s. We use a cross-disciplinary approach combining genetics, transport modelling, survey time series analyses and physical oceanographic modelling to investigate 3 hypotheses on the reasons for this change. Evidence from connectivity studies suggests that the population of North Sea anchovy is separate from that in the Bay of Biscay. The recruitment pulses observed in survey data fit a life cycle which includes spawning in early summer and larval development in late summer. This also supports the concept of population expansion originating from local remnant population(s). In terms of growth physiology, suitable thermal windows...
Tipo: Text
Palavras-chave: Climate variability; Small pelagic fish; Regime shift; Temperature; Anchovy; North Sea.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00060/17140/14638.pdf

Rapport sur l'utilisation du sondeur multifaisceaux ME70 lors des campagnes Pelgas08 et Class08
Provedor de dados: 5
Autores: Doray, Mathieu; Petitgas, Pierre; Masse, Jacques; Trenkel, Verena.
Report on Simrad ME70 multibeam echosounder operations during Pelgas08 and Class08 sea surveys. First observations of small pelagic fish 3D aggregative structures
Tipo: Text
Palavras-chave: Pelagic ecosystem; Bay of Biscay; 3D fisheries acoustics; Multibeam echosounder; Écosystème pélagique; Golfe de Gascogne; Acoustique halieutique 3D; Sondeur multifaisceaux.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/rapport-6314.pdf

Estimation de la biomasse de stocks de poissons par acoustique
Provedor de dados: 5
Autores: Doray, Mathieu; Petitgas, Pierre; Masse, Jacques.
Estimer la biomasse d'un stock de poissons par acoustique nécessite de combiner des données de nature diverse collectées le long du parcours d'échantillonnage (Woillez et al., 2009). Il s'agit essentiellement de combiner trois champs de données spatialisées : une carte de densités acoustiques attribuées aux poissons, une carte de proportions d'espèces et une carte de longueurs moyennes.
Tipo: Text
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00003/11447/7997.pdf

Data products for fish stocks and ecosystem assessment:the PELGAS survey example
Provedor de dados: 5
Autores: Doray, Mathieu; Petitgas, Pierre; Romagnan, Jean-baptiste; Huret, Martin; Duhamel, Erwan; Dupuy, Christine; Spitz, Jérôme; Berger, Laurent; Dorémus, Ghislain; Bourriau, Paul; Grellier, Patrick; Massé, Jacques; Sanchez, Florence.
The initial objective of the PELGAS integrated survey was to assess the biomass of small pelagic fish in the Bay of Biscay in spring. Sampling has been extended to study the spatial structure and dynamics of the pelagic ecosystem in springtime. The PELGAS survey has produced since 2000 long-term time-series of spatially-explicit data and indices, describing the main pelagic ecosystem components: hydrology, phytoplankton, mesozooplankton, fish and megafauna. In addition to small pelagic fish biomass estimates used for fish stock assessment, the survey now delivers two types of ecosystem products: standard gridded maps of ecosystem parameters, and a time series dataset of indicators of the Bay of Biscay pelagic ecosystem state. The evolution of the PELGAS...
Tipo: Text
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00457/56844/58693.pdf

A 37 years hindcast of a coupled physical-biogeochemical model and its use for fisheries oceanography in the Bay of Biscay
Provedor de dados: 5
Autores: Huret, Martin; Petitgas, Pierre; Struski, Caroline; Leger, Fabien; Sourisseau, Marc; Lazure, Pascal.
Overexploitation and climate change are increasingly causing unanticipated changes in marine ecosystems, such as higher variability in fish recruitment and shifts in species distribution, pressing for developing fisheries oceanography. In the meantime, operational oceanography rapidly progresses and its products become easy to access to a large community, among them fisheries scientists. Multiyear oceanographic reanalyses (hindcasts) were identified has a priority product by the ICES WG on Operational Oceanographic Products for Fisheries and Environment (WGOOFE). We performed a 37 years hindcast (1972-2008) run with a coupled physical-biogeochemical model (ECO-MARS3D) over the Bay of Biscay, using realistic meteorological and run-off forcing. We first...
Tipo: Text
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00023/13432/10442.pdf

A behavioural fish movement approach within an anchovy IBM model to study fish migration patterns in the Bay of Biscay
Provedor de dados: 5
Autores: Politikos, Dimitrios; Huret, Martin; Petitgas, Pierre.
Modelling of fish movement behaviour within a heterogeneous marine environment is a challenging but also key issue for understanding the effect of environmental factors and climatic change on fish processes (growth, distribution, mortality, reproduction). Fish movement models have the capability to encompass the combined effect of environment and empirical knowledge of fish individuals as energy requirements, known preys and predators, swimming capacities into a unified framework. Following an Individual Based Model (IBM) approach, a fish movement model has been developed to simulate the active movement of adult anchovy in the Bay of Biscay (BoB) in response to the spatio-temporal variations of both biotic and abiotic factors, as well as its internal...
Tipo: Text
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00176/28709/27161.pdf

The influence of environment and spawning distribution on the survival of anchovy (Engraulis encrasicolus) larvae in the Bay of Biscay (NE Atlantic) investigated by biophysical simulations
Provedor de dados: 5
Autores: Allain, Gwenhael; Petitgas, Pierre; Lazure, Pascal.
A growth and survival model of the early life stages was run along virtual drift trajectories tracked in a hydrodynamic model to simulate the annual recruitment process of anchovy (Engraulis encrasicolus) in the Bay of Biscay (NE Atlantic). These biophysical simulations concerning three different years were analysed in order to investigate the influence of environment and spawning dynamics on the survival of larvae and juveniles. The location of space-time survival windows suggested major environmental mechanisms involved in simulated recruitment variability at the different scales - retention of larvae and juveniles in favourable habitats over the shelf margins and turbulence effects. These small-scale and meso-scale mechanisms were related to the...
Tipo: Text
Palavras-chave: Turbulence; Retention; Recruitment; Physical biological interactions; Larval survival; IBM; Biscay; Anchovy.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-3423.pdf

Bioenergetic condition of anchovy and sardine in the Bay of Biscay and English Channel
Provedor de dados: 5
Autores: Gatti, Paul; Cominassi, Louise; Duhamel, Erwan; Grellier, Patrick; Le Delliou, Herve; Le Mestre, Sophie; Petitgas, Pierre; Rabiller, Manuella; Spitz, Jerome; Huret, Martin.
There is a growing interest in monitoring body condition of marine organisms in the context of the ecosystem approach to fisheries and global change. Fish condition is under the influence of environmental variability on seasonal scale, but also on longer timescales. It represents a good indicator of habitat quality or individual fitness, and is also a relevant parameter to evaluate energy transfer through the trophic chain. However, the sources of variability in fish condition need to be accurately understood and the significance of existing indices has to be correctly assessed. Here, we measured the energy density, a precise and global indicator of fish bioenergetic condition, for anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) in the...
Tipo: Text
Palavras-chave: Energy density; Calorimetry; Small pelagic fish; Engraulis encrasicolus; Sardina pilchardus; Northeast Atlantic.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00416/52754/53615.pdf

Spatial strategies of fish populations
Provedor de dados: 5
Autores: Petitgas, Pierre.
Tipo: Text
Ano: 1994
URL: http://archimer.ifremer.fr/doc/00396/50753/51463.pdf

Populations ichtyologiques de petits pélagiques. Sous-région marine Golfe de Gascogne. Evaluation initiale DCSMM.
Provedor de dados: 5
Autores: Petitgas, Pierre; Massé, Jacques; Huret, Martin; Doray, Mathieu; Duhamel, Erwan.
Tipo: Text
Palavras-chave: Golfe de Gascogne; Petits pélagiques; Espèces; Biocénose; Etat des stocks.
Ano: 2012
URL: https://archimer.ifremer.fr/doc/00329/44028/43600.pdf

A multi-decadal hindcast of a physical–biogeochemical model and derived oceanographic indices in the Bay of Biscay
Provedor de dados: 5
Autores: Huret, Martin; Sourisseau, Marc; Petitgas, Pierre; Struski, Caroline; Leger, Fabien; Lazure, Pascal.
Multiple year oceanographic simulations (hindcast) are identified as a priority oceanography product for fisheries and environment studies since they provide a unique continuous long-term dataset allowing integrated assessment of the ocean state and evolution. We performed a 37 year (1972–2008) hindcast run with a coupled physical–biogeochemical model in the Bay of Biscay. The coupled model and the hindcast configuration are described. A model skill assessment is performed with a large set of in-situ data. Average seasonal currents show major circulation patterns over the shelf. Among tracers, temperature and salinity have the best agreement, ahead of nitrates and silicates, chlorophyll, and finally phosphates and ammonium. For chlorophyll, improved...
Tipo: Text
Palavras-chave: Physical-biogeochemical model; Hindcast; Skill assessment; Environmental indices; Seasonal pattern; Interannual variability; Fisheries oceanography; Bay of Biscay.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00114/22538/20237.pdf

Impacts of climate change on the complex life cycles of ﬁsh
Provedor de dados: 5
Autores: Petitgas, Pierre; Rijnsdorp, Adriaan D.; Dickey-collas, Mark; Engelhard, Georg H.; Peck, Myron A.; Pinnegar, John; Drinkwater, Kenneth F.; Huret, Martin; Nash, Richard.
To anticipate the response of fish populations to climate change, we developed a framework that integrates requirements in all life stages to assess impacts across the entire life cycle. The framework was applied on plaice (Pleuronectes platessa) and Atlantic herring (Clupea harengus) in the North Sea, Atlantic cod (Gadus morhua) in the Norwegian/Barents Seas and European anchovy (Engraulis encrasicolus) in the Bay of Biscay. In each case study, we reviewed habitats required by each life stage, habitat availability, and connectivity between habitats. We then explored how these could be altered by climate change. We documented environmental processes impacting habitat availability and connectivity, providing an integrated view at the population level and in...
Tipo: Text
Palavras-chave: Connectivity; Habitat; Eco-physiology; Anchovy; Herring; Plaice; Cod.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00118/22935/20798.pdf

Using min/max autocorrelation factors of survey-based indicators to follow the evolution of fish stocks in time
Provedor de dados: 5
Autores: Woillez, Mathieu; Rivoirard, Jacques; Petitgas, Pierre.
Fisheries research monitoring surveys provide an ensemble of measurements on fish stocks and their environment. Because the interannual variability in such survey-based indicators is high and because diagnostics on fish stocks cannot be based on noise, our concern is to make use of what is continuous in time to obtain a reliable diagnostic. In this paper, we show how min/max autocorrelation factors (MAFs) can be useful for assessing the status of a fish stock. Indeed, MAFs will allow us to (i) summarize the multivariate indicator signals into orthogonal factors that are continuous in time, (ii) select those indicators that carry the major signal in time, and (iii) forecast stock status by modelling the time continuity of the MAFs. These different potential...
Tipo: Text
Palavras-chave: Fish stock diagnostics; Survey based indicators; Time correlation; Min/max autocorrelation factors.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6759.pdf

Detection of changes in time-series of indicators using CUSUM control charts
Provedor de dados: 5
Autores: Mesnil, Benoit; Petitgas, Pierre.
Statistical Process Control (SPC) methods are extensively used in manufacturing contexts to monitor production processes. This article illustrates their potential utility for monitoring the state of marine ecosystems, using survey indicators. We exemplify the use of one SPC tool, the cumulative sum (CUSUM) control chart, to detect persistent changes in the state of a system as new observations are collected, using simulated and real data. Practical guidelines are given on how the chart parameters can be tuned to achieve an acceptable compromise between the ability to detect anomalies quickly and keeping the risk of false alarms low. The common performance measures associated with control charts depend on some key assumptions being met, and the potential...
Tipo: Text
Palavras-chave: Aquatic resource monitoring; CUSUM; Statistical process control.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6689.pdf

Spatially explicit estimation of fish length histograms, with application to anchovy habitats in the Bay of Biscay
Provedor de dados: 5
Autores: Petitgas, Pierre; Doray, Mathieu; Masse, Jacques; Grellier, Patrick.
Fish length frequency histograms from research surveys are of prime importance for identifying habitats of different life stages, as well as for stock assessment. However, no method has thus far been available for mapping these histograms as spatially varying curves. Here, a procedure is applied to map spatially connected curves, and detail is given on how it can be applied to map the length frequency histograms. At each sample location, a fish length frequency histogram is given as a vector of non-independent values. The histogram is first modelled as a polynomial expansion on the basis of orthogonal polynomials. Then, the polynomial coefficients are mapped by co-kriging, after fitting a model of co-regionalization. The length frequency map is finally...
Tipo: Text
Palavras-chave: Co-kriging; European anchovy; Fish length; Functional kriging; Habitat; Mapping curves.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00049/16042/13581.pdf

Rapport sur l'utilisation du sondeur multifaisceaux ME70 lors de la campagne Pelgas09
Provedor de dados: 5
Autores: Doray, Mathieu; Masse, Jacques; Petitgas, Pierre; Trenkel, Verena.
Le sondeur multifaisceaux Simrad ME70 (ou SMFH) (Trenkel et al., 2008) a été utilisé pour la première fois en routine en parallèle des sondeurs monofaisceaux ER60 lors de la campagne Pelgas09 (25/04-05/06/2009).  Le premier objectif était de tester la faisabilité d'une utilisation en routine du ME70 lors d'une campagne visant à évaluer par acoustique les stocks d'anchois et de sardine du Golfe de Gascogne.  A terme, les données récoltées lors de cette campagne permettront d'étudier l'apport du sondeur multifaisceaux ME70 à l'estimation de biomasse, en comparant les estimations de stocks obtenues en mono et multifaisceaux.  Les données acoustiques 3D collectées au moyen du ME70 dans l'ensemble du Golfe de Gascogne lors de Pelgas09 doivent également...
Tipo: Text
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/rapport-6755.pdf

A 38 years hindcast of a coupled physical-biogeochemical model and derived indices for fisheries oceanography
Provedor de dados: 5
Autores: Huret, Martin; Petitgas, Pierre; Sourisseau, Marc; Struski, Caroline; Leger, Fabien; Lazure, Pascal.
Operational oceanography rapidly progresses and its products become easy to access to a large community, among them fisheries scientists. The products cover both near real-time environment information (on scales of days to weeks) but also retrospective analysis providing long time series of environment parameters. Here we describe a 38 years hindcast of a coupled physical-biogeochemical model of the Bay of Biscay as well as the indices and major information that were derived from it.
Tipo: Text
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00023/13454/10466.pdf

Energy density of anchovy Engraulis encrasicolus in the Bay of Biscay
Provedor de dados: 5
Autores: Dubreuil, Julien; Petitgas, Pierre.
The energy density (E-D) of anchovy Engraulis encrasicolus in the Bay of Biscay was determined by direct calorimetry and its evolution with size, age and season was investigated. The water content and energy density varied seasonally following opposite trends. The E-D g(-1) of wet mass (M-W) was highest at the end of the feeding season (autumn: c. 8 kJ g(-1) M-W) and lowest in late winter (c. 6 kJ g(-1) M-W). In winter, the fish lost mass, which was partially replaced by water, and the energy density decreased. These variations in water content and organic matter content may have implications on the buoyancy of the fish. The water content was the major driver of the energy density variations for a M-W basis. A significant linear relationship was...
Tipo: Text
Palavras-chave: Seasonal cycle; Reserves; Bioenergetics.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6143.pdf

Lower trophic levels and detrital biomass control the Bay of Biscay continental shelf food web: Implications for ecosystem management
Provedor de dados: 5
Autores: Lassalle, G.; Lobry, J.; Le Loc'H, F.; Bustamante, Paco; Certain, Gregoire; Delmas, Daniel; Dupuy, C.; Hily, Christian; Labry, Claire; Le Pape, O.; Marquis, Elise; Petitgas, Pierre; Pusineri, Claire; Ridoux, Vincent; Spitz, J.; Niquil, Nathalie.
The Bay of Biscay (North-East Atlantic) has long been subjected to intense direct and indirect human activities that lead to the excessive degradation and sometimes overexploitation of natural resources. Fisheries management is gradually moving away from single-species assessments to more holistic, multi-species approaches that better respond to the reality of ecosystem processes. Quantitative modelling methods such as Ecopath with Ecosim can be useful tools for planning, implementing and evaluating ecosystem-based fisheries management strategies. The aim of this study was therefore to model the energy fluxes within the food web of this highly pressured ecosystem and to extract practical information required in the diagnosis of ecosystem state/health. A...
Tipo: Text
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00057/16851/14329.pdf

Variation in life-history traits of European anchovy along a latitudinal gradient: a bioenergetics modelling approach
Provedor de dados: 5
Autores: Huret, Martin; Tsiaras, K; Daewel, U; Skogen, Md; Gatti, Paul; Petitgas, Pierre; Somarakis, S.
Anchovy Engraulis encrasicolus distribution in European waters spans from the Mediterranean Sea to the North Sea, and is expected to expand further north with global warming. Observations from the eastern Mediterranean (North Aegean Sea), the Bay of Biscay and the North Sea reveal latitudinal differences in growth, maximum size, fecundity and timing of reproduction. We set up a mechanistic framework combining a bioenergetics model with regional physical-biogeochemical models providing temperature and zooplankton biomass to investigate the underlying mechanisms of variation in these traits. The bioenergetics model, based on the Dynamic Energy Budget theory and initially calibrated in the Bay of Biscay, was used to simulate growth and reproduction patterns....
Tipo: Text
Palavras-chave: Engraulis encrasicolus; Countergradient variation; Growth; Reproduction; Dynamic Energy Budget theory; Bay of Biscay; Aegean Sea; North Sea.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00504/61564/65489.pdf

Manual of recommended practices for modelling physical – biological interactions during fish early life
Provedor de dados: 5
Autores: North, Elizabeth W.; Gallego, Alejandro; Petitgas, Pierre.
The objectives of this manual of recommended practices (MRP) are to summarize appropriate methods for modelling physical – biological interactions during the early life of fish, to recommend modelling techniques in the context of specific applications, and to identify gaps in knowledge. This manual is intended to provide a reference for early‐career modellers who are interested in applying numerical models to fish early life and who would benefit from a summary of recommended practices for coupled biological – physical models that incorporate predictions from threedimensional circulation models to determine the transit of fish eggs, larvae, and juveniles from spawning to nursery areas. For current practitioners of numerical modelling in fish early life,...
Tipo: Text
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00157/26792/24888.pdf

Modeling fish growth and reproduction in the context of the Dynamic Energy Budget theory to predict environmental impact on anchovy spawning duration
Provedor de dados: 5
Autores: Pecquerie, Laure; Petitgas, Pierre; Kooijman, Sebastiaan.
Spawning location and timing are critical for understanding fish larval survival. The impact of a changing environment on spawning patterns is, however, poorly understood. A novel approach is to consider the impact of the environment on individual life histories and subsequent spawnings. In the present work, we extend the Dynamic Energy Budget (DEB) theory to investigate how environment variability impacts the spawning timing and duration of a multiple-batch spawning species. The model is successfully applied to reproduce the growth and reproduction of anchovy (Engraulis encrasicolus) in the Bay of Biscay. The model captures realistically the start and ending of the spawning season, including the timing of the spawning events, and the change in egg number...
Tipo: Text
Palavras-chave: Bay of Biscay; Engraulis encrasicolus; Starvation; Environmental conditions; Condition factor; Multiple Batch Spawning; Reproductive Biology; DEB Theory.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6769.pdf

Pelagic fish stock assessment by acoustic methods at Ifremer
Provedor de dados: 5
Autores: Doray, Mathieu; Masse, Jacques; Petitgas, Pierre.
The main objective of Ifremer's pelagic sea surveys (Pelgas in the Bay of Biscay and Pelmed in the Gulf of Lion) is to assess the biomass of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) populations, based on fisheries acoustic data. Complementary data on the whole pelagic ecosystem (hydrology, plankton, fish eggs and larvae, other fish species, seabirds and marine mammals) are also collected during the cruises. This document describes the procedures used to derive stock abundance estimates from acoustic and fishing data collected during sea cruises, the Pelgas sea survey being used as an example.
Tipo: Text
Ano: 2010
URL: https://archimer.ifremer.fr/doc/00003/11446/7996.pdf

Managing Fisheries in the context of an integrated policy: the importance of spatial issues
Provedor de dados: 5
Autores: Petitgas, Pierre; Ernande, Bruno; Andonegi, Eider; Fabi, Gianna; Scarcella, Guiseppe; Kapiris, Kostas; Leocadio, Ana.
A variety of conservation policies now frame the management of fishing activity and so do also the spatial planning of different sectorial activities. These framework policies are additional to classical fishery management. There is a risk that the policies applying on the marine system are not coherent from a fisheries point of view. The spatial management of fishing activity at regional scale has the potential to meet multiple management objectives, on a habitat basis. Here we consider how to integrate multiple objectives of different policies into integrated ocean management scenarios. In the EU, European Directives and the CFP are now implementing the ecosystem approach to the management of human activity at sea. In this context, we further identify...
Tipo: Text
Palavras-chave: Ecosystem approach; Integration; Spatial; Policy.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00353/46380/46002.pdf

Introduction: status and future of modelling physical-biological interactions during the early life of fishes
Provedor de dados: 5
Autores: Gallego, A; North, E; Petitgas, Pierre.
Modelling physical-biological interactions in the early life of fish is becoming an integral part of theoretical and applied marine ecology. A workshop on 'Advancements in modelling physical-biological interactions in fish early-life history' (WKAMF) was held in April 2006 to review recent developments and identify future research directions. Here we provide an overview of the information presented at WKAMF (some of which is published in this Theme Section), discussions that took place at the workshop, and the authors' perspectives as workshop co-Chairs. The major themes identified at the workshop were the need for enhanced model validation and sensitivity methods and improved understanding of physical and biological processes. Using the appropriate level...
Tipo: Text
Palavras-chave: Workshop; Individual based methods; Larvae; Eggs; Fish; Biophysical modelling.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-4311.pdf

Dispersal kernels and their drivers captured with a hydrodynamic model and spatial indices: A case study on anchovy (Engraulis encrasicolus) early life stages in the Bay of Biscay
Provedor de dados: 5
Autores: 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
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00024/13544/10577.pdf

Use of a disjunctive kriging to model areas of high pelagic fish density in acoustic fisheries surveys
Provedor de dados: 5
Autores: Petitgas, Pierre.
Schooling fish may aggregate in very high densities covering very small areas. Thus the probability of hitting such high-density spots during a large-scale sampling is very low. The sampling fluctuations of the tail of the histogram are thought to be very significant. The stock biomass estimate and its precision rely greatly on how precisely the tail of the histogram can be sampled. In order to acquire elements for improving survey designs and abundance estimators wc study here the relation in space that the high values have with the other values. A disjunctive kriging approach is used. Different quantiles of the histogram are coded by indicators. The spatial structure of each indicator and its spatial covariation with the others are studied by computing...
Tipo: Text
Palavras-chave: Distribution spatiale; Agrégation; Abondance; Estimation; Géostatistique; Échantillonnage; Spatial distribution; Aggregation; Abundance estimation; Geostatistics; Sampling.
Ano: 1993
URL: http://archimer.ifremer.fr/doc/00190/30076/28564.pdf

Multidisciplinary integrated surveys: objectives, achievements and future directions
Provedor de dados: 5
Autores: Petitgas, Pierre; Santos Vasquez, Begona.
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00434/54607/55989.pdf

Spring habitats of small pelagic fish communities in the Bay of Biscay
Provedor de dados: 5
Autores: Doray, Mathieu; Hervy, Camille; Huret, Martin; Petitgas, Pierre.
Mapping habitats of species communities helps to inform on the ecological processes which drive their distribution. This information is critical to identify suitable areas for spatial management, aimed at preserving biodiversity, ecosystem functions or essential habitats. While demersal fish have been extensively studied at the community scale, small pelagic fish have mainly been characterised at the population scale. This paper presents a community-based approach on the biodiversity of small pelagic fish, with the aim to: (i) define small pelagic fish communities, (ii) characterise their spatial and interannual dynamics, and (iii) assess their habitats. We present a Multiple Factor Analysis (MFA)-based method that characterises the spatio-temporal...
Tipo: Text
Palavras-chave: Habitat; Small pelagic fish; Bay of Biscay; Spatial distribution; Multiple Factor Analysis.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00411/52236/53046.pdf

Exploring Change in the Relative Abundance of Marine Megafauna in the Bay of Biscay, 2004-2016
Provedor de dados: 5
Autores: Authier, Matthieu; Doremus, Ghislain; Van Canneyt, Olivier; Boubert, Jean-jacques; Gautier, Gerard; Doray, Mathieu; Duhamel, Erwan; Masse, Jacques; Petitgas, Pierre; Ridoux, Vincent; Spitz, Jerome.
Conservation has moved from species-centered to ecosystem-based approaches: the Marine Strategy Framework Directive requires the maintenance or restoration of ‘Good Environmental Status’ of all European marine waters. Monitoring biodiversity at the scale of whole ecosystems is salient, but challenging owing to the large spatial scale involved and the large spatio-temporal heterogeneity of marine ecosystems. We capitalized on the integrated ecosystemic PELGAS survey carried out in spring in the Bay of Biscay to document patterns of change in marine megafauna relative abundance at the community level over more than a decade (2004-2016). The relative abundance of the twenty three most frequently sighted species (6 cetaceans and 17 seabirds) was estimated by...
Tipo: Text
Palavras-chave: Marine megafauna; Relative abundance; MSFD; Ecosystemic surveys.
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00403/51405/51981.pdf

Selection and validation of a complex fishery model using an uncertainty hierarchy
Provedor de dados: 5
Autores: Lehuta, Sigrid; Petitgas, Pierre; Mahevas, Stephanie; Huret, Martin; Vermard, Youen; Uriarte, Andres; Record, Nicholas R.
Assessing the validity of a model is essential for its credibility especially when the model is used as decision making tool. Complex dynamic fishery models are recommended to investigate the functioning of fisheries and to assess the impact of management strategies, particularly spatial fishing regulations. However, their use is limited due to the difficulty and computational cost of parameterizing and gaining confidence, particularly for parameter rich models. These difficulties are compounded by uncertainty regarding parameter values, many of which are often taken from literature or estimated indirectly. Here we propose a methodology to improve confidence and understanding in the model, easily transferable to any complex model. The approach combines...
Tipo: Text
Palavras-chave: Bay of Biscay anchovy; Dynamic fishery model; Model selection; Uncertainty; Validation.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00148/25965/24150.pdf

Densité des oeufs d'anchois (Engraulis encrasicolus) et de sardines (Sardina pilchardus) dans le golfe de Gascogne
Provedor de dados: 5
Autores: Couraudon-reale, Marine; Huret, Martin; Bourriau, Paul; Taraud, Laure; Petitgas, Pierre.
Tipo: Text
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00023/13375/10400.pdf

Habitat selection and phenotypic diversity in the anchovy of the Bay of Biscay
Provedor de dados: 5
Autores: Petitgas, Pierre; Grellier, Patrick; Leseur, Floriane; Lenfant, Philippe.
Diversity among individuals in a population is an important feature linking vital rates with behaviour and spatial occupation. We measured the growth increments in the otolith of individual fishes collected on the annual fisheries survey PELGAS from 2001 to 2015. Individuals who grew larger at juvenile stage occupied later in life more off-shore habitats. Further, we analysed the allozymes of 13 different loci from 2001 to 2006. Alleles of the enzyme IDH showed different frequencies in inshore and offshore habitats. The population spatially segregates along a coast to off-shore gradient with individuals showing different early growth and allele frequencies. Results show how individuals in a population segregate spatially in different habitats in relation...
Tipo: Text
Palavras-chave: Allozymes; Otoliths; Habitats; Spatial distribution; Anchovy.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00353/46379/46001.pdf

Conséquences du changement climatique sur les écosystèmes marins exploités par la pêche et la conchyliculture
Provedor de dados: 5
Autores: Petitgas, Pierre; Ulrich, Clara; Auber, Arnaud; Gourguet, Sophie; Huret, Martin; Mazurais, David; Pernet, Fabrice; Pouvreau, Stephane; Richard, Marion; Servili, Arianna; Thebaud, Olivier; Zambonino Infante, Jose-luis.
Tipo: Text
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00657/76942/78148.pdf

Towards an ecosystem approach to fisheries management (EAFM) when trawl surveys provide the main source of information
Provedor de dados: 5
Autores: Cotter, John; Petitgas, Pierre; Abella, Alvaro; Apostolaki, Panayiota; Mesnil, Benoit; Politou, Chrissi-yianna; Rivoirard, Jacques; Rochet, Marie-joelle; Spedicato, Maria Teresa; Trenkel, Verena; Woillez, Mathieu.
Ideas and considerations are put forward for managing fisheries and marine populations using primarily trawl surveys to supply biological and spatial indicators of the state of stocks, and to permit catch per unit effort (CPUE)-based assessments. Trawl surveys seldom allow absolute estimates of fish population sizes but, if appropriately located, timed, and designed, can provide a broad range of information about catchable fish species and the ecosystem that supports them. This information may be more conducive to sustainable management of fisheries than the traditional focus on the abundances of selected stocks. The paper first briefly proposes how survey-based methods might supplement existing fishery-dependent stock assessments, as would be necessary...
Tipo: Text
Palavras-chave: Fishing effort indicator; Fisheries independent assessment; Survey based stock assessment; Spatial indicator; State indicator; Trawl survey; Fisheries management.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6691.pdf

Springtime zooplankton size structure over the continental shelf of the Bay of Biscay
Provedor de dados: 5
Autores: Vandromme, Pierre; Nogueira, Enrique; Huret, Martin; Lopez-urrutia, Angel; Gonzalez-nuevo Gonzalez, G.; Sourisseau, Marc; Petitgas, Pierre.
Linking lower and higher trophic levels requires special focus on the essential role played by mid-trophic levels, i.e., the zooplankton. One of the most relevant pieces of information regarding zooplankton in terms of flux of energy lies in its size structure. In this study, an extensive data set of size measurements is presented, covering parts of the western European continental shelf and slope, from the Galician coast to the Ushant front, during the springs from 2005 to 2012. Zooplankton size spectra were estimated using measurements carried out in situ with the Laser Optical Plankton Counter (LOPC) and with an image analysis of WP2 net samples (200 μm mesh size) performed following the ZooScan methodology. The LOPC counts and sizes particles within...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00221/33246/31744.pdf

Monitoring small pelagic fish in the Bay of Biscay ecosystem, using indicators from an integrated survey
Provedor de dados: 5
Autores: Doray, Mathieu; Petitgas, Pierre; Huret, Martin; Duhamel, Erwan; Romagnan, Jean-baptiste; Authier, Matthieu; Dupuy, Christine; Spitz, Jerome.
This paper is a practical contribution to two important debates raised by the implementation of marine ecosystem based management: (i) which ecosystem data can be provided by a fisheries survey optimised for ecosystem monitoring; and (ii) how to combine/select potential indicators to derive useful information on marine ecosystem status and dynamics? A suite of 143 potential indicators, including spatial indices, representing small pelagic fish and their biotic and abiotic environments are presented. Indicators were routinely derived from the PELGAS integrated ecosystem survey conducted in spring in the Bay of Biscay (BoB). The general patterns over time in this suite of 5–16 years, non-stationary time series are characterised using a methodology based on...
Tipo: Text
Palavras-chave: Min/max autocorrelation factors; Time correlation; Survey-based indicators; Marine Strategy Framework Directive; Ecosystem variability; Bay of Biscay; Pelagic ecosystem.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00414/52552/53443.pdf

Rapport Final – Projet CAPTAIN. Connaissances Améliorées à l'aide des Pêcheurs sur la sArdIne et l'ANchois de la façade Atlantque - Bilan 2015-2018
Provedor de dados: 5
Autores: Huret, Martin; Duhamel, Erwan; Gatti, Paul; Lebigre, Christophe; Le Mestre, Sophie; Petitgas, Pierre; Rabiller, Manuella; Guigue, Thierry; Joguet, Manon; Maillet, Jérome.
Le projet FFP Captain visait à l’amélioration des connaissances biologiques et sur la connectivité des stocks de sardine et d’anchois sur la façade Atlantique française (Manche et golfe de Gascogne). Il a reposé sur la collecte de données au travers d’une collaboration avec les professionnels de la pêche (organisations de producteurs et pêcheurs) et de l’exploitation opportuniste des pêches sur l’ensemble des campagnes halieutiques de la zone (PELGAS, EVHOE, CGFS). Ceci a permis une couverture spatiale et saisonnière optimale. Nous avons ainsi affiné la description spatio-temporelle de la reproduction pour les deux espèces, et montré une plus forte croissance ainsi qu’une densité énergétique plus élevées en Manche que dans le golfe de Gascogne. Cette...
Tipo: Text
Palavras-chave: Anchois; Sardine; Petts pélagiques; Golfe de Gascogne; Manche; Collaboraton scientifques–pêcheurs; Génétque; Calorimétrie.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00586/69764/67655.pdf

Manual of fisheries survey protocols. PELGAS surveys (PELagiques GAScogne)
Provedor de dados: 5
Autores: Doray, Mathieu; Badts, Vincent; Masse, Jacques; Duhamel, Erwan; Huret, Martin; Doremus, Ghislain; Petitgas, Pierre.
The PELGAS sea cruises aim at monitoring the Bay of Biscay pelagic ecosystem, in order to provide scientific data for the implementing of an ecosystemic management of Biscay living ressources. The spatial and temporal dynamics of small pelagic fish populations are specifically monitored, with a focus on anchovy populations. The cruise hence takes place in spring, during anchovy spawning, to allow for the assessment of both eggs and adult stages. The PELGAS ecosystemic cruise aims at collecting data at each level of the Biscay trophic chain. Data are collected continuously along parallel transects covering the whole Bay of Biscay, in order to thoroughly characterize the horizontal and vertical structures of the pelagic ecosystem. Multibeam and...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00191/30259/28714.pdf

Notes on survey-based spatial indicators for monitoring fish populations
Provedor de dados: 5
Autores: Woillez, Mathieu; Rivoirard, Jacques; Petitgas, Pierre.
This paper presents the spatial indicators used in the European project FISBOAT. These are statistics intended to capture spatial patterns of fish populations, using fish density data collected during scientific surveys. To handle diffuse population limits, indicators are designed not to depend on arbitrary delineation of the domain. They characterize the location (centre of gravity and spatial patches), occupation of space (inertia, isotropy, positive area, spreading area and equivalent area) and microstructure. Collocation between different populations is summarized by a global index of collocation. These spatial indicators have the potential to be used in a monitoring system to detect changes in spatial distribution. They could be helpful for relating...
Tipo: Text
Palavras-chave: Fish populations; Spatial patterns; Monitoring; Spatial indicators.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6687.pdf

Guide du chef de mission de la campagne PELGAS
Provedor de dados: 5
Autores: Doray, Mathieu; Badts, Vincent; Huret, Martin; Duhamel, Erwan; Doremus, Ghislain; Masse, Jacques; Petitgas, Pierre.
L'édition des Guides du chef de mission des campagnes halieutiques vise en particulier les campagnes inscrites dans des séries de relevés pluri-annuels (campagnes benthiques, démersales et pélagiques). Mais elle concerne également toutes les campagnes halieutiques dont les données sont déposées auprès du Système d'information halieutique - campagnes à la mer. Cette documentation sur la campagne PELGAS est publiée pour répondre aux objectifs suivants : - Constituant le complément opérationnel aux manuels des protocoles des campagnes halieutiques, les Guides du chef de mission fournissent aux chefs de mission et aux équipes embarquées une documentation de base leur permettant de maîtriser l'ensemble des opérations à conduire pendant les campagnes. Ils...
Tipo: Text
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00249/36054/34604.pdf

Biophysical modelling of larval drift, growth and survival for the prediction of anchovy (Engraulis encrasicolus) recruitment in the Bay of Biscay (NE Atlantic)
Provedor de dados: 5
Autores: Allain, Gwenhael; Petitgas, Pierre; Lazure, Pascal; Grellier, Patrick.
Fish recruitment is the result of the integration of small-scale processes affecting larval survival over a season and large oceanic areas. A hydrodynamic model was used to explore and model these physical-biological interaction mechanisms and then to perform the integration from individual to population scales in order to provide recruitment predictions for fisheries management. This method was applied to the case of anchovy (Engraulis encrasicolus) in the Bay of Biscay (NE Atlantic). The main data available to investigate survival mechanisms were past growth (otolith) records of larvae and juveniles sampled at sea. The drift history of these individuals was reconstructed by a backtracking procedure using hydrodynamic simulations. The relationships...
Tipo: Text
Palavras-chave: Recruitment; Physical biological interactions; Individual based models; Biscay; Anchovy.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-3422.pdf

A partnership between science and industry for a monitoring of anchovy &amp; sardine in the Bay of Biscay: When fishermen are actors of science
Provedor de dados: 5
Autores: Masse, Jacques; Sanchez, Florence; Delaunay, Damien; Robert, J. M.; Petitgas, Pierre.
Anchovy and sardine are small pelagic species occupying similar geographic areas in the Bay of Biscay (North-East Atlantic). Their biomass is strongly dependent on recruitment, making the annual assessment of TAC (Total Allowable Catch) a risky strategy due to uncertainty in predicting the magnitude of recruitment. Monitoring these resources more often and throughout their life cycle could allow management strategies to be adjusted based on observations which indicate the level of recruitment. In order to achieve a more frequent monitoring, an innovative data collection strategy involving a partnership between fishermen and scientists, was developed in 2009 and 2010 called “pilot sentinel surveys”. This paper details the partnership, the information such a...
Tipo: Text
Palavras-chave: Sporadic acoustic surveys; Bay of Biscay; Small pelagic monitoring; Recruitment indicators; Fishermen's surveys.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00301/41214/41006.pdf

Interannual Changes in Biomass Affect the Spatial Aggregations of Anchovy and Sardine as Evidenced by Geostatistical and Spatial Indicators
Provedor de dados: 5
Autores: 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
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00276/38758/37299.pdf

Precision of acoustic fish abundance estimates: separating the number of schools from the biomass in the schools
Provedor de dados: 5
Autores: Marchal, Emile; Petitgas, Pierre.
The gulf of Cariaco, Venezuela, is a rather isolated piece of coastal ocean where spatio-temporal variability has been measured. In 1986, three repeated surveys have been carried out in this gulf. The important differences in biomass estimates are attributed to sampling error only. The biological nature of this variability is studied. It is due to a high concentration of the biomass in a few schools and correlatively to the hit or the miss of these large schools, during the sampling. Structural information for predicting them is sought. Also, the number of schools per elementary sampling distance unit (ESDU) and the biomass in each school were measured by echointegration. It is found that there is no clear relation between these two variables. Thus their...
Tipo: Text
Palavras-chave: Evaluation des stocks; Campagnes acoustiques; Précision; Stock assessment; Echo surveys; Reliability.
Ano: 1993
URL: http://archimer.ifremer.fr/doc/00190/30077/28565.pdf

A simulation-based approach to assess sensitivity and robustness of fisheries management indicators for the pelagic fishery in the Bay of Biscay
Provedor de dados: 5
Autores: Lehuta, Sigrid; Mahevas, Stephanie; Le Floc'H, Pascal; Petitgas, Pierre.
Indicators are widely promoted as means to monitor ecosystem status or to evaluate fisheries management performance. "Which indicators are most relevant as decision-support tools in fisheries management?" still remains a topical question. Indicators should be metrics related to fish populations and fleets and should be sensitive to management strategies. However, given the complexity of the processes involved, it is often difficult to unequivocally interpret variations in metrics. A simulation approach was used to study metric properties and to identify robust and relevant fishery indicators. By applying sensitivity analysis methods, simulation designs were built that cross a variety of management scenarios and uncertainty hypotheses. Bio-economic outputs...
Tipo: Text
Ano: 2013
URL: https://archimer.ifremer.fr/doc/00170/28093/26627.pdf

Environmental and stock effects on the recruitment of anchovy in the Bay of Biscay : a multivariate analysis
Provedor de dados: 5
Autores: Allain, Gwenhael; Petitgas, Pierre; Lazure, Pascal.
Variability in anchovy recruitment in Biscay is temptatively explained using variables from the stock and from the environment during the ichtyoplankton phase. Anchovy recruitment depends on many different processes : weight of adults and proportion of multiple spawners (age 2), river discharges, upwelling events at the coast and at the shelf break. Meteorological variables (wind, rain, tempe rature ) are forcing effects on the sea but they are not the effective processes that govern the production in the sea. So they do not relate directly to the survival of larvae and to recruitment. In Biscay, many different physical processes are active and used by anchovy which spawns in different physical systems (river plumes, open ocean enrichment systems)....
Tipo: Text
Palavras-chave: Bio-physical coupling; Recruitment; Anchovy; Hdrodynamics; Step by step regression.
Ano: 1999
URL: http://archimer.ifremer.fr/doc/00391/50190/50814.pdf

Relationships between population spatial occupation and population dynamics
Provedor de dados: 5
Autores: Woillez, Mathieu; Petitgas, Pierre; Rivoirard, Jacques; Fernandes, Paul; Hoftstede, Remment Ter; Korsbrekke, Knut; Orlowski, Andrzej; Spedicato, Maria-teresa; Politou, Chrissi-yianna.
Population dynamics is commonly described non-spatially using parameters of population demography and vital traits. Population spatial organisation is therefore considered implicit and its importance in the population dynamics ignored. The present study evidences on a variety of stocks correlation between population spatial distribution indices, population abundance, recruitment and mortality. Series of research fisheries monitoring surveys were considered for a range of different stocks (cod, herring, anchovy, hake, mullet) in different regions of the North East Atlantic and Mediterranean (North Sea, Barents Sea, Baltic Sea, Bay of Biscay, Tyrrhenian Sea, Ionian Sea and Aegean Sea). For each population, each age and each year, 9 spatial indices were...
Tipo: Text
Palavras-chave: Spatial indices population dynamics; Meta-analysis.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/00133/24376/22388.pdf

Understanding what controls the spatial distribution of fish populations using a multi-model approach
Provedor de dados: 5
Autores: Planque, Benjamin; Loots, Christophe; Petitgas, Pierre; Lindstrom, Ulf; Vaz, Sandrine.
Understanding and predicting the distribution of organisms in heterogeneous environments lies at the heart of ecology. The spatial distribution of fish populations observed in the wild results from the complex interactions of multiple controls both external or internal to the fish populations. Whilst species distribution models (SDMs) have been mostly concerned with static description of species distribution as a function of environmental constraints, models of animal movements (MAMs) have focussed on the dynamic nature of spatial distribution of groups of individuals under a number of constraints external and internal to the population. Besides SDMs and MAMs, modelling the spatial distribution of fish populations can be achieved by models that are...
Tipo: Text
Palavras-chave: Demographic structure; Density-dependent habitat selection; Environmental control; Fish spatial distribution models; Multi-model inference; Population memory; Spatial dependency.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00022/13309/10360.pdf

Modélisation couplée physique-biogéochimie du golfe de Gascogne sur la période 1971-2007
Provedor de dados: 5
Autores: Huret, Martin; Struski, Caroline; Leger, Fabien; Petitgas, Pierre; Lazure, Pascal; Sourisseau, Marc.
Une simulation 'hindcast' de la dynamique physique et biogéochimique du golfe de Gascogne a été réalisée pour la période 1971-2007 à l'aide du modèle ECO-MARS3D. Ce modèle couplant physique et biogéochimie fournit une série longue de données simulées, moyennées ou intégrées sur 3 jours (température, salinité, sels nutritifs, phytoplancton, zooplancton), qui sont ensuite utilisées pour des calculs d'indices hydrologiques 2D synthétiques (indices méso-échelle : stratification, upwellings, surface tourbillonnaire ; indices biologiques : chlorophylle-a de surface, production primaire intégrée). Nous nous proposons dans ce document de présenter la configuration et les forçages utilisés pour cette simulation, et de lister les différentes variables sauvegardées...
Tipo: Text
Palavras-chave: Projet FP6 RECLAIM; Halieutique; Indices hydrologiques; Hindcast; ECO MARS3D; Modélisation couplée; Golfe de Gascogne.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/rapport-5164.pdf

Anchovy (Engraulis encrasicolus) egg density measurements in the Bay of Biscay: evidence for the spatial variation in egg density with sea surface salinity
Provedor de dados: 5
Autores: Goarant, Anne; Petitgas, Pierre; Bourriau, Paul.
Knowledge of the pelagic vertical distribution of fish eggs is central for several aspects of fisheries science including fisheries recruitment and egg production studies. In modelling egg vertical distributions, variation in fish egg density is an important issue. Though variation in egg density between individual eggs has been reported, evidence for significant spatial variation in egg density is novel. The present study provides evidence that egg density of anchovy (Engraulis encrasicolus) varies spatially across spawning sites in the Bay of Biscay, depending on the regional scale variation in sea water properties due to river discharge. We measured the density of the eggs using a density gradient column at 17 stations in 2005 and 2006 as well as their...
Tipo: Text
Palavras-chave: Bay of Biscay; Anchovy; Fish egg density; Density gradient column.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-3007.pdf

Integrated understanding of initial conditions of early life stages using integrated ecosystem survey data
Provedor de dados: 5
Autores: Petitgas, Pierre; Huret, Martin; Doray, Mathieu; Bourriau, Paul; Lunven, Michel.
Since 2000, the yearly acoustic pelagic survey of Ifremer in the Bay of Biscay designed for fish stock assessment of small pelagic fish has been converted into an integrated pelagic ecosystem monitoring plateforme. This has been achieved by coupling sensors and automating data acquisition streams. The data series now spans from 2000 to 2014. Together with data sensors and sampling designs, we present here an integrated study allowing to understand the spawning process of anchovy. We compare the maps of anchovy eggs obtained with CUFES (continuous underway fish egg sampler) with that of their spawning adults sampled at the same time by acoustics and identification trawl hauls. The distributions of eggs are surprisingly different than that of adults, with in...
Tipo: Text
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00281/39177/37738.pdf

A coupled movement and bioenergetics model to explore the spawning migration of anchovy in the Bay of Biscay
Provedor de dados: 5
Autores: Politikos, Dimitrios; Huret, Martin; Petitgas, Pierre.
Adult anchovies in the Bay of Biscay perform north to south migration from late winter to early summer for spawning. However, what triggers and drives the geographic shift of the population remains unclear and poorly understood. An individual-based fish model has been implemented to explore the potential mechanisms that control anchovy's movement routes toward its spawning habitats. To achieve this goal, two fish movement behaviors – gradient detection through restricted area search and kinesis – simulated fish response to its dynamic environment. A bioenergetics model was used to represent individual growth and reproduction along the fish trajectory. The environmental forcing (food, temperature) of the model was provided by a coupled...
Tipo: Text
Palavras-chave: Individual-based model; Behavioral movement; Dynamic Energy Budget; Anchovy; Bay of Biscay.
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00273/38446/36868.pdf

Integration of bioenergetics in an individual-based model to hindcast anchovy dynamics in the Bay of Biscay
Provedor de dados: 5
Autores: Bueno-pardo, Juan; Petitgas, Pierre; Kay, Susan; Huret, Martin.
The population of European anchovy of the Bay of Biscay collapsed at the beginning of the 21st century, causing the closure of its fishery between 2005 and 2010. In order to study both the human and environmental causes of the anchovy population dynamics, an approach coupling individual bioenergetics to an individual-based model was applied between 2000 and 2015. This modelling framework was forced with outputs from a physical–biogeochemical model. In addition to a base-case scenario with realistic forcing, alternative scenarios were run without inter-annual variability in either fishing mortality or environmental conditions. During the decrease in population biomass, a high fishing pressure coincided with a combination of environmental variables promoting...
Tipo: Text
Palavras-chave: Anchovy; Bay of Biscay; Dynamic Energy Budget; Fishery; Harvest control rule; Individual-based model; Population collapse.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00598/70984/69272.pdf

Hydro-plankton characteristics and their relationship with sardine and anchovy distributions on the French shelf of the Bay of Biscay
Provedor de dados: 5
Autores: Petitgas, Pierre; Masse, Jacques; Bourriau, Paul; Beillois, Pierre; Bergeron, Jean-pierre; Delmas, Daniel; Herbland, Alain; Koueta, Noussithe; Froidefond, Jean-marie; Santos, Maria.
The spatial pattern in hydro-plankton and fish distributions and their relationship were analysed based on the spring 2000 fisheries acoustic survey. The importance of this survey was that it was a multi-disciplinary platform which collected an extensive set of parameters in the hydro-plankton leading to a potentially finer description of hydro-plankton conditions and fish habitats. More than 50 variables were measured on a grid of stations, in four compartments of the ecosystem: hydrology, nutrients, primary producers and meso-zooplankton. First, a joint analysis of all hydro-plankton compartments was performed using multiple factor analysis (MFA). The method was used to estimate a compromise factorial space common to all compartments in which the...
Tipo: Text
Palavras-chave: Fish environment relationship; Hydro plankton; Habitats; Multiple factor analysis; Spatial pattern.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-3961.pdf

Characterization of sound scattering layers in the Bay of Biscay using broadband acoustics, nets and video
Provedor de dados: 5
Autores: Blanluet, Arthur; Doray, Mathieu; Berger, Laurent; Romagnan, Jean-baptiste; Le Bouffant, Naig; Lehuta, Sigrid; Petitgas, Pierre.
Sound scattering layers (SSLs) are observed over a broad range of spatio-temporal scales and geographical areas. SSLs represent a large biomass, likely involved in the biological carbon pump and the structure of marine trophic webs. Yet, the taxonomic composition remains largely unknown for many SSLs. To investigate the challenges of SSL sampling, we performed a survey in a small study area in the Northern Bay of Biscay (France) by combining broadband and narrowband acoustics, net sampling, imagery and video recordings. In order to identify organisms contributing to the observed SSLs, we compared measured frequency spectra to forward predicted spectra derived from biological data. Furthermore, to assess the confidence in SSL characterization, we evaluated...
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00588/70035/67955.pdf

Influence of planktonic foodweb structure on a system's capacity to support pelagic production: an inverse analysis approach
Provedor de dados: 5
Autores: Marquis, Elise; Niquil, Nathalie; Vezina, Alain F.; Petitgas, Pierre; Dupuy, Christine.
Coupled plankton/small pelagic (SP) fish systems were analysed to assess how foodweb structure influences the export of carbon to pelagic fish during the spring bloom in the Bay of Biscay. The investigation of carbon export flows through inverse analysis was supplemented by estimating the carrying capacity for pelagic fish production by applying linear programming. A planktonic foodweb dominated by microbial pathways had the highest trophic efficiency owing to the tight coupling between planktonic trophic levels and predation pressure on mesozooplankton by fish. Moreover, the magnitude of the gap between carrying capacity and estimated carbon export was related to the size structure of primary producers, with the picophytoplankton-based foodweb having the...
Tipo: Text
Palavras-chave: Bay of Biscay; Carbon export; Carrying capacity; Inverse analysis; Planktonic foodweb; Small pelagic fish.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00035/14583/13375.pdf

Variability and controls of otolith growth in the anchovy of the Bay of Biscay
Provedor de dados: 5
Autores: Petitgas, Pierre; Grellier, Patrick; Duhamel, Erwan; Masse, Jacques; Doray, Mathieu.
Individual fish growth depends on internal population factors such as phenotypic variability as well as external factors such as past environmental conditions (temperature, food) and selective mortality (predation or fishing). In the anchovy, growth in the first year is key to population dynamics as it determines the potential energy allocated to reproduction as well as the capacity to occupy off-shore habitats. Further, in the recent past, the anchovy in the bay of Biscay has experienced collapse and recovery and the role played by growth in this history is unknown. Since 2001 with the spring acoustic survey series PelGas, we have monitored individual fish growth by measuring in the otolith the increments between annual rings, in addition to age...
Tipo: Text
Palavras-chave: Anchovy; Biscay; Otoliths; Growth; Metapopulation.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00114/22550/20236.pdf

Fifteen years of data from the PELGAS integrated survey (2000-2015): what have we learned on the Bay of Biscay pelagic ecosystem?
Provedor de dados: 5
Autores: Doray, Mathieu; Petitgas, Pierre; Romagnan, Jean-baptiste; Huret, Martin; Duhamel, Erwan; Dupuy, Christine; Spitz, Jérôme; Authier, Matthieu; Berger, Laurent; Doremus, Ghislain; Bourriau, Paul; Grellier, Patrick; Masse, Jacques; Sanchez, Florence.
The initial focus of the PELGAS integrated survey was to assess the small pelagic fish biomass in the Bay of Biscay in springtime, for fisheries management purposes. Sampling has been extended to produce long-term time-series of spatially-explicit data and indices, describing the main pelagic ecosystem components: hydrology, phytoplankton, mesozooplankton, fish and megafauna. A collaborative analysis of these datasets has brought new insights on the Bay of Biscay pelagic ecosystem summarized here. New results on single ecosystem components include an analysis of water samples to groundtruth the results of an ocean color algorithm aiming at detecting phytoplanktonic coccolithophores. New insights on mesozooplankton spatio-temporal distribution and energy...
Tipo: Text
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00445/55665/57331.pdf

Density dependence in the spatial behaviour of anchovy and sardine across Mediterranean systems
Provedor de dados: 5
Autores: Giannoulaki, Marianna; Petitgas, Pierre; Barra, Marco; Tugores, Pilar; Vasapollo, C.; Iglesias, M.; Leonori, Iole; De Felice, Andrea; Bonanno, A.; Basilone, G.; Mazzola, Salvatore; Bigot, Jean-louis; Machias, Athanassios; Pyrounaki, Maria M.
A spatial indicator—the spreading area index—is used to describe anchovy and sardine spatial distribution in relation to biomass variation and to look for ecosystem differences within the Mediterranean basin. Specifically, the variation in the spreading area index in relation to biomass was examined for different areas of the Mediterranean Sea (i.e. Aegean Sea, western Adriatic Sea, Strait of Sicily, Gulf of Lion, and Spanish Mediterranean waters). In order to capture the spatial variability of the population at different levels of fish density, acoustic survey data for the years of highest, lowest, and intermediate abundance were used. In a subsequent step standardized values of spreading area and biomass were estimated to allow comparisons.  Results...
Tipo: Text
Palavras-chave: Anchovy; Mediterranean Sea; Sardine; Spreading area index.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00114/22549/20245.pdf

Interaction between fish and fishing vessels in the Javanese purse seine fishery
Provedor de dados: 5
Autores: Potier, Michel; Petitgas, Pierre; Petit, Didier.
The purse-seiners of the Java Sea use light and fish aggregating devices (FAD) to concentrate and catch small pelagic fish (Decapterus sp., Amblygaster sirm, Sardinella gibbosa). This sets a question about the interaction between fish and fishing vessels. Relevant estimates of fishing mortality and fishing effort require an understanding of this interaction. To gain information on this relationship, acoustic surveys were performed on the fishing grounds and the present paper analyses these data. Using acoustic surveys, the fish density was measured and the number of schools was counted per sea surface unit. The fishing vessels were located by radar. Acoustic data were stratified into two groups, one where fishing vessels were present and the other where...
Tipo: Text
Palavras-chave: Pêche; Acoustique; Structures spatiales; Pélagiques; Mer de Java; Indonésie; Fishing operation; Echo surveys; Spatial structure; Pelagic fish; Java Sea; Indonesia.
Ano: 1997
URL: http://archimer.ifremer.fr/doc/00188/29884/28343.pdf

A Geostatistical Definition of Hotspots for Fish Spatial Distributions
Provedor de dados: 5
Autores: Petitgas, Pierre; Woillez, Mathieu; Doray, Mathieu; Rivoirard, Jacques.
Research surveys at sea are undertaken yearly to monitor the distribution and abundance of fish stocks. In the survey data, a small number of high fish concentration values are often encountered, which denote hotspots of interest. But statistically, they are responsible for important uncertainty in the estimation. Thus understanding their spatial predictability given their surroundings is expected to reduce such uncertainty. Indicator variograms and cross-variograms allow to understand the spatial relationship between values above a cutoff and the rest of the distribution under that cutoff. Using these tools, a “top” cutoff can be evidenced above which values are spatially uncorrelated with their lower surroundings. Spatially, the geometric set...
Tipo: Text
Palavras-chave: Hotspots; Indicators; Non-linear geostatistics; Multivariate geostatistics; Anchovy; Biscay.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00273/38380/36734.pdf

Estimation de la précision des campagnes acoustiques au Sénégal par la méthode géostatistique transitive à une dimension
Provedor de dados: 5
Autores: Samb, Birame; Petitgas, Pierre.
This study presents an application of the geostatistical one-dimensional (1D) transitive method for estimating the precision of acoustic pelagic abundance estimates in Senegal. In applying the method, the major problem encountered was how to take into account the temporal variability in the computation of the estimation variance. In acoustic surveys, echointegration is performed continuously along the ship's sailing track. For a survey design made of parallel transects, each transect can thus be considered as a sampling unit. By summing the density values along the transects to obtain biomass values per transect, the 2D estimation is simply reduced to a 1D estimation procedure. If the transects are equidistant, the geostatistical transitive method applied...
Tipo: Text
Palavras-chave: Céostatistique; Variance; Acoustique; Abondance; Geostatistics; Variance; Acoustics; Abundance.
Ano: 1997
URL: http://archimer.ifremer.fr/doc/00188/29883/28348.pdf

WGACEGG acoustic and egg-based survey products for monitoring anchovy and sardine populations in the European Atlantic area ecosystem
Provedor de dados: 5
Autores: Doray, Mathieu; Angelico, Maria Manuel; Iglesias, Magdalena; Jimenez, Paz; Marques, Vitor; Ramos, Fernando; Rodriguez-climent, Silvia; Santos, Maria; Van Der Kooij, Jeroen; Petitgas, Pierre.
The Working Group on Acoustic and Egg Surveys (WGACEGG) coordinates the pelagic integrated surveys in ICES Areas 7, 8 and 9. Those surveys provide fisheries-independent, acoustic and/or egg-based estimates of the biomass and demographic structure of sardine and anchovy populations. Survey biomass estimates are the main inputs used to manage those commercially important small pelagic stocks in the European Atlantic area (EAA). Taking advantage of the fine spatial resolution of acoustic and egg data, and of ancillary ecosystem data provided by integrated pelagic surveys, WGACEGG also compile standard gridded maps of anchovy and sardine eggs and adult biomass, as well as maps of key in-situ hydrological parameters (surface salinity and temperature). We...
Tipo: Text
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00457/56841/58650.pdf

Populations ichtyologiques de petits pélagiques. Sous-région marine Mers celtiques. Evaluation initiale DCSMM.
Provedor de dados: 5
Autores: Petitgas, Pierre; Massé, Jacques; Huret, Martin; Doray, Mathieu; Duhamel, Erwan.
Tipo: Text
Ano: 2012
URL: https://archimer.ifremer.fr/doc/00328/43948/43521.pdf

Populations ichtyologiques démersales du plateau continental. Sous-région marine Manche - Mer du Nord. Evaluation initiale DCSMM.
Provedor de dados: 5
Autores: Vérin, Yves; Vaz, Sandrine; Coppin, Franck; Delpech, Jean-paul; Mahé, Kelig; Petitgas, Pierre; Bez, Nicolas.
Tipo: Text
Palavras-chave: Manche; Mer du Nord; Poissons démersaux; Plateau continental; Espèces sensibles.
Ano: 2012
URL: https://archimer.ifremer.fr/doc/00327/43842/43416.pdf

COSELMAR. Compréhension des socio-écosystèmes littoraux et marins pour la prévention et la gestion des risques. Bilan scientifique 2013-2017
Provedor de dados: 5
Autores: Pardo, Sophie; Hess, Philipp; Simon, Elodie; Barille, Laurent; Geslin, Emmanuelle; Cognie, Bruno; Martin-jezequel, Véronique; Sechet, Véronique; Herrenknecht, Christine; Baron, Regis; Bourseau, Patrick; Amzil, Zouher; Masse, Anthony; Vandanjon, Laurent; Dumay, Justine; Lebeau, Thierry; Turpin, Vincent; Mondeguer, Florence; Petitgas, Pierre; Trouillet, Brice; Mercier, Denis; Guillotreau, Patrice; Guineberteau, Thierry; Mahevas, Stephanie; Schoefs, Franck; Sophie Pardo; Philipp Hess; Pauline Borgniet; Laurent Barillé; Emmanuelle Geslin; Bruno Cognie; Véronique Martin-Jezequel; Véronique Sechet; Christine Herrenknecht; Régis Baron; Patrick Bourseau; Zouher Amzil; Anthony Massé; Laurent Vandanjon; Justine Dumay; Thierry Lebeau; Vincent Turpin; Florence Mondeguer; Pierre Petitgas; Brice Trouillet.
COSELMAR, a 4-year project financed by the Région des Pays de la Loire at 2.1 M€, officially started on the 7th January 2013. The project is coordinated by Philipp Hess (IFREMER) and Sophie Pardo (Université de Nantes-LEMNA) and falls under the Federation for Research Institut Universitaire Mer et Littoral (IUML, FR CNRS 3473)*. COSELMAR has also been approved by the Scientific Council of the MSH Ange Guépin. COSELMAR is a research project uniting 5 research units of IFREMER and 11 laboratories of the Université de Nantes, along with academic partners, and national and international industries. The aim is to achieve a better understanding of the marine and coastal ecosystems and the associated resources. The project will also provide insights into risk...
Tipo: Text
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00406/51793/52550.pdf

Reconstructing individual food and growth histories from biogenic carbonates
Provedor de dados: 5
Autores: Pecquerie, Laure; Fablet, Ronan; De Pontual, Helene; Bonhommeau, Sylvain; Alunno-bruscia, Marianne; Petitgas, Pierre; Kooijman, Sebastiaan A. L. M.
Environmental conditions experienced by aquatic organisms are archived in biogenic carbonates such as fish otoliths, bivalve shells and coral skeletons. These calcified structures present an accretionary growth and variations in optical properties - color or opacity - that are used to reconstruct time. Full and reliable exploitation of the information extracted from these structures is, however, often limited as the metabolic processes that control their growth and their optical properties are poorly understood. Here, we propose a new modeling framework that couples both the growth of a biogenic carbonate and its optical properties with the metabolism of the organism. The model relies on well-tested properties of Dynamic Energy Budget (DEB) theory. It is...
Tipo: Text
Palavras-chave: Otolith; Calcification; Metabolism; Bioenergetic model; Food reconstruction; Dynamic Energy Budget theory.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00060/17082/14593.pdf

The ZooCAM, a new in-flow imaging system for fast onboard counting, sizing and classification of fish eggs and metazooplankton
Provedor de dados: 5
Autores: Colas, Florent; Tardivel, Morgan; Perchoc, Jonathan; Lunven, Michel; Forest, Bertrand; Guyader, Gerard; Danielou, Marie-madeleine; Le Mestre, Sophie; Bourriau, Paul; Antajan, Elvire; Sourisseau, Marc; Huret, Martin; Petitgas, Pierre; Romagnan, Jean-baptiste.
In this paper we present the ZooCAM, a system designed to digitize and analyse on board large volume samples of preserved and living metazooplankton (i.e. multicellular zooplankton) and fish eggs &gt; 300 µm ESD. The ZooCAM has been specifically designed to overcome the difficulties to analyse zooplankton and fish eggs in the framework of the PELGAS survey, and provide high frequency data. The ZooCAM fish eggs counts were comparable to those done with a dissecting microscope. The ZooCAM enabled the accurate prediction and fast on board validation of staged anchovy and sardine eggs in almost real time after collection. A comparison with the ZooScan, on a more complex zooplanktonic community, provided encouraging results on the agreement between the 2...
Tipo: Text
Palavras-chave: ZooCAM; In-flow imaging; Fish eggs; Zooplankton; Ecosystemic survey.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00407/51833/52432.pdf

Assessing natural mortality of Bay of Biscay anchovy from survey population and biomass estimates
Provedor de dados: 5
Autores: Uriarte, Andres; Ibaibarriaga, Leire; Pawlowski, Lionel; Masse, Jacques; Petitgas, Pierre; Santos, Maria; Skagen, Dankert.
La fermeture de la pêche de l’anchois (Engraulis encrasicolus) du Golfe de Gascogne entre 2005 et 2010, en raison de la faible biomasse du stock, a été une opportunité pour estimer la mortalité naturelle à partir de données de campagnes halieutiques issues de l’observation de la présence d’oeufs (DEPM) et de mesures acoustiques, utilisées pour l’évaluation de cette population depuis 1987. En considérant que la mortalité naturelle est constante au cours du temps et que la capturabilité des deux campagnes est identique pour tous les âges, la mortalité naturelle peut être estimée par des modèles log-linéaires appliquées aux séries temporelles de nombres aux âges issues des campagnes, et par des modèles d’évaluations de stock prenant en compte la saison....
Tipo: Text
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00334/44510/45923.pdf

The CUSUM out-of-control table to monitor changes in fish stock status using many indicators
Provedor de dados: 5
Autores: Petitgas, Pierre.
One method to assess fish stocks using a suite of indicators is the traffic light approach. In this approach, the time series of the different indicators are mapped on a common colour scale to highlight alerts that occur when indicators cross reference limit values. Until now, however, the procedure has lacked a statistical framework. Here, we propose the cumulative sum (CUSUM) monitoring scheme as a suitable statistical framework. CUSUM is a statistical process control method that detects deviations from a reference mean, according to defined performance criteria. With the CUSUM monitoring scheme, alarm signals can be triggered when indicators cross defined in-control limits that correspond to defined probabilities of false alarm and non-alarm (i.e.,...
Tipo: Text
Palavras-chave: Integrated assessment; Traffic light approach; Monitoring; CUSUM; Indicators.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6690.pdf

Connectivity patterns of anchovy larvae in the Bay of Biscay from a coupled transport-bioenergetic model forced by size-structured zooplankton
Provedor de dados: 5
Autores: Huret, Martin; Vandromme, Pieter; Petitgas, Pierre; Pecquerie, Laure.
Connectivity during early life stages of pelagic fish, defined here by survival probability between spawning and early juvenile habitats, depends on a combination of sufficient food availability and low predator encounter along drift trajectories. For anchovy in the Bay of Biscay, larval transport experiments throughout the spawning season suggest accumulation of early juveniles in the offshore area of the southern Bay, as well as retention over the mid-shelf at mid-latitude. However, late summer-early autumn surveys suggest presence of juveniles only in the former region. From this observation, we set up a bioenergetic individual based model to test for the effect of food availability on survival patterns. The model couples a Lagrangian transport module...
Tipo: Text
Palavras-chave: Connectivity; Larval IBM; Bioenergetics; Zooplankton; Bay of Biscay; European anchovy.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00105/21655/19237.pdf

Variation that can be expected when using particle tracking models in connectivity studies
Provedor de dados: 5
Autores: Hufnagl, Marc; Payne, Mark; Lacroix, Genevieve; Bolle, Loes J.; Daewele, Ute; Dickey-collas, Mark; Gerkema, Theo; Huret, Martin; Janssen, Frank; Kreus, Markus; Paetsch, Johannes; Pohlmann, Thomas; Ruardij, Piet; Schrum, Corinna; Skogen, Morten D.; Tiessen, Meinard C. H.; Petitgas, Pierre; Van Beek, Jan K. L.; Van Der Veer, Henk W.; Callies, Ulrich.
Hydrodynamic Ocean Circulation Models and Lagrangian particle tracking models are valuable tools e.g. in coastal ecology to identify the connectivity between offshore spawning and coastal nursery areas of commercially important fish, for risk assessment and more for defining or evaluating marine protected areas. Most studies are based on only one model and do not provide levels of uncertainty. Here this uncertainty was addressed by applying a suite of 11 North Sea models to test what variability can be expected concerning connectivity. Different notional test cases were calculated related to three important and well-studied North Sea fish species: herring (Clupea harengus), and the flatfishes sole (Solea solea) and plaice (Pleuronectes platessa). For sole...
Tipo: Text
Palavras-chave: Ocean circulation; Lagrangian approach; Variability; Marine protected areas; Renewable energy; Wind park; Model intercomparison; Ensemble.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00385/49660/50198.pdf

Investigating the coupling between small pelagic fish and marine top predators using data collected from ecosystem-based surveys
Provedor de dados: 5
Autores: Certain, G.; Masse, Jacques; Van Canneyt, O.; Petitgas, Pierre; Doremus, G.; Santos, M. B.; Ridoux, Vincent.
The present study is a general multivariate analysis of the spatial association between small pelagic fishes and their predators (seabirds, marine mammals and fisheries), using 6 yr (18000 km) of transects surveyed in spring in the Bay of Biscay, France. We describe 4 groups of prey-predator association, with explicit distinction of prey size: (1) terns and anchovies (10 to 15 cm), (2) common dolphins, common murres, sprat and sardine (&lt;20 cm), (3) gannets, horse mackerel and mackerel (15 to 25 cm) and (4) bottlenose dolphin, horse mackerel and mackerel (25 to 40 cm). Our analysis also illustrates the great variability in these associations, with years of strong prey-predator associations followed by years of weak relationships. The analysis allows us...
Tipo: Text
Palavras-chave: Marine top predators; Small pelagic fishes; Spatial associations; Temporal variability; Pelagic ecosystem; Bay of Biscay.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00031/14257/11540.pdf

Survey timing vs. ecosystem scheduling: Degree-days to underpin observed interannual variability in marine ecosystems
Provedor de dados: 5
Autores: Huret, Martin; Bourriau, Paul; Doray, Mathieu; Gohin, Francis; Petitgas, Pierre.
Fishery annual surveys are shifting towards integrated ecosystem surveys. However, monitoring the whole ecosystem once a year entails special attention to the interpretation of observations, because they only represent a snapshot in the seasonal dynamics of the environment, of a species, or any dynamic process of interest. The dependency of this snapshot to the timing, but also to the duration, of the survey with respect to this seasonal dynamics needs to be considered. Fish stock assessment is only little impacted by the observed timing within a given season, whereas warming, stratification, plankton bloom occurrence, or fish fecundity, are processes rapidly changing especially in spring. Firstly, from independent satellite data, we described the seasonal...
Tipo: Text
Palavras-chave: Ecosystem survey; Anchovy; Sardine; Spawning; Sea surface temperature; Degree day; Bay of Biscay.
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00394/50584/51483.pdf

Organisation géographique des populations de poissons marins
Provedor de dados: 5
Autores: Petitgas, Pierre.
The management of marine fish stocks has stayed non-spatial, considering spatial distributions and their consequences on demography as implicit. But the impacts of climate change and the anthropisation of habitats now require to consider spatial procedures explicitly. The work presented here starts with the question of evaluating population abundance, which requires the modelling of spatial distributions (section 1). Then an ecological understanding of the multi-scale nature of distributions is investigated (section 2). Last, we study how demographic population dynamics depends on the spatial organisation of life cycles (section 3). In this work, the approach has been to combine data acquisition at sea with statistical characterisation and modelling. The...
Tipo: Text
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00013/12410/9197.pdf

Analysing Temporal Variability in Spatial Distributions Using Min–Max Autocorrelation Factors: Sardine Eggs in the Bay of Biscay
Provedor de dados: 5
Autores: 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

Indices for capturing spatial patterns and their evolution in time, with application to European hake (Merluccius merluccius) in the Bay of Biscay
Provedor de dados: 5
Autores: 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

Combining sensitivity and uncertainty analysis to evaluate the impact of management measures with ISIS-Fish: marine protected areas for the Bay of Biscay anchovy (Engraulis encrasicolus) fishery
Provedor de dados: 5
Autores: Lehuta, Sigrid; Mahevas, Stephanie; Petitgas, Pierre; Pelletier, Dominique.
Spatio-seasonal explicit simulation models can predict the impact of spatial management measures on marine fish populations and fishing activities. As fisheries are complex systems, fisheries simulation models are often complex, with many uncertain parameters. Here, the methodology is provided to deliver fishery diagnostics within an uncertainty context using a complex simulation tool. A sensitivity analysis of the model is performed on model outputs using partial least-squares to identify the most sensitive parameters. The impact of several management measures is then simulated using a statistical simulation design taking into account the uncertainty of the selected sensitive parameters. This approach was applied to the Bay of Biscay anchovy stock using...
Tipo: Text
Palavras-chave: Bay of Biscay anchovy; Marine protected area; Sensitivity analysis; Simulation; Uncertainty analysis.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00011/12234/9281.pdf

Combining acoustic and CUFES data for the quality control of fish-stock survey estimates
Provedor de dados: 5
Autores: Petitgas, Pierre; Goarant, Anne; Masse, Jacques; Bourriau, Paul.
Petitgas, P., Goarant, A., Masse, J., and Bourriau, P. 2009. Combining acoustic and CUFES data for the quality control of fish-stock survey estimates. - ICES Journal of Marine Science, 66: 1384-1390.
Tipo: Text
Palavras-chave: CUFES; Biscay; Bias; Anchovy; Acoustics; Abundance.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6566.pdf

In-situ measurements of the individual acoustic backscatter of European anchovy (Engraulis encrasicolus) and sardine (Sardina Pilchardus), with concurrent optical identification
Provedor de dados: 5
Autores: Doray, Mathieu; Berger, Laurent; Coail, Jean-yves; Vacherot, Jean-philippe; Bavouzet, Gerard; Petitgas, Pierre.
The lack of specific Target Strength (TS) values for European anchovy (Engraulis encrasicolus) and sardine (Sardina Pilchardus) in the literature has been pointed out by the Working Group on Acoustic and Egg Surveys for Sardine and Anchovy in ICES Areas VIII and IX. The need for specific small pelagics TS measurements conducted in controlled environments was recognized by the group, to further investigate the adequacy of TS length equation used to derive fish stock estimates for clupeids in European waters. TS is a stochastic variable which largely varies in the wild, in response to changes in physical (tilt angle, depth) or biological (physiology) single fish attributes. The first requirement to make sound TS measurement is to accurately identify of the...
Tipo: Text
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00055/16637/14133.pdf

Stock collapses and their recovery: mechanisms that establish and maintain life-cycle closure in space and time
Provedor de dados: 5
Autores: Petitgas, Pierre; Secor, Dave H.; Mcquinn, Ian; Huse, Geir; Lo, Nancy.
Experience has established that the recovery of many collapsed stocks takes much longer than predicted by traditional fishery population models. We put forward the hypothesis that stock collapse is associated with disruption of the biological mechanisms that sustain life-cycle closure of intrapopulation contingents. Based on a review of case studies of nine marine fish stocks, we argue that stock collapses not only involve biomass loss, but also the loss of structural elements related to life-cycle diversity (contingents), as well as the breakdown of socially transmitted traditions (through a curtailed age range). Behavioural mechanisms associated with these structural elements could facilitate recovery of depleted populations. Migratory behaviour is...
Tipo: Text
Palavras-chave: Behaviour; Collapse; Life-cycle diversity; Recovery.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00021/13186/10262.pdf

Ecosystem spatial structure revealed by integrated survey data
Provedor de dados: 5
Autores: Petitgas, Pierre; Huret, Martin; Dupuy, Christine; Spitz, Jerome; Authier, Matthieu; Romagnan, Jean-baptiste; Doray, Mathieu.
Integrated marine survey series such as PELGAS provide comprehensive geo-referenced data over large sea areas in major ecosystem components with defined biological resolution and spatio-temporal sampling scale. These data enable to develop product at different levels of biological organization and spatial scale that are useful for ecosystem integrated assessments. Using the PELGAS integrated data series, we applied a generic procedure made of several steps to identify and map ecologically coherent ecosystem spatial units in the Bay of Biscay. First, the data were interpolated on a common spatial grid and organized as a time series of matrices containing at each time the variables as columns and the grid cell values as rows. The multi-table analysis method...
Tipo: Text
Palavras-chave: Integrated surveys; Ecosystems; Spatial structure; Multi-factor analysis; Bay of Biscay; Pelagic.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00403/51402/51977.pdf

Populations ichtyologiques de petits pélagiques. Sous-région marine Manche - Mer du Nord. Evaluation initiale DCSMM.
Provedor de dados: 5
Autores: Vérin, Yves; Vaz, Sandrine; Coppin, Franck; Delpech, Jean-paul; Mahé, Kelig; Petitgas, Pierre; Bez, Nicolas.
Tipo: Text
Palavras-chave: Manche; Mer du Nord; Petits pélagiques; Espèces; Biocénose; Etat des stocks.
Ano: 2012
URL: https://archimer.ifremer.fr/doc/00327/43843/43417.pdf

Fish stock assessments using surveys and indicators
Provedor de dados: 5
Autores: Petitgas, Pierre; Cotter, John; Trenkel, Verena; Mesnil, Benoit.
Tipo: Text
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6686.pdf

Size, permeability and buoyancy of anchovy (     Engraulis Encrasicolus     ) and sardine (     Sardina Pilchardus     ) eggs in relation to their physical environment in the Bay of Biscay
Provedor de dados: 5
Autores: Huret, Martin; Bourriau, Paul; Gatti, Paul; Dumas, Franck; Petitgas, Pierre.
The size and specific gravity of eggs of marine pelagic fish partly determine their dispersal and survival. Using an original dataset of anchovy and sardine eggs, sampled in spring over the last decade in the Bay of Biscay, we provide a parameterization of these properties on ambient water temperature and salinity. We used the density gradient column for measurement of egg specific gravity. The column was also filled with homogeneous water for sinking velocity experiments. For anchovy, these experiments confirm that the effect of egg permeability through the chorion could be neglected when modelling sinking, while it has to be considered for sardine, its perivitelline space representing 78.6% (±6.2%) of the total egg volume, as opposed to 5–10% for most...
Tipo: Text
Palavras-chave: Anchovy; Bay of Biscay; Density gradient column; Egg buoyancy; Egg permeability; Egg size; Sardine.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00346/45676/45326.pdf

Modelling the variability in fish spatial distributions over time with empirical orthogonal functions: anchovy in the Bay of Biscay
Provedor de dados: 5
Autores: Petitgas, Pierre; Doray, Mathieu; Huret, Martin; Masse, Jacques; Woillez, Mathieu.
Characterizing the space–time variability in spatial distributions as well as understanding its drivers is basic to designing robust spatial management plans. As a prerequisite, we analyse here how this variability relates to population dynamics in conjunction with environmental conditions. For that, spatio-temporal statistical approaches are needed but seldom used in fisheries science. To fill this gap, we showcase the usefulness of the method of empirical orthogonal functions (EOFs). Guidelines are given to apply the method on a series of gridded maps as derived from fisheries survey dataseries that now span over decades. The method is applied to the series, 2000–2012, of the spatial distributions of European anchovy in the Bay of Biscay at spawning...
Tipo: Text
Palavras-chave: Anchovy; Bay of Biscay; Density-dependence; EOF; Habitat; Spatial distribution.
Ano: 2014
URL: https://archimer.ifremer.fr/doc/00222/33365/31907.pdf

Impact du changement climatique sur les populations de petits pélagiques des façades françaises. Atleier CERES, éléments de synthèse
Provedor de dados: 5
Autores: Lehuta, Sigrid; Huret, Martin; Issac, Pierre; Petitgas, Pierre.
CERES a pour objectif de mieux comprendre comment le changement climatique influencera les ressources les plus importantes de poissons et de crustacés d'Europe ainsi que les actvités économiques qui en dépendent. CERES fournira des outils et des stratégies d'adaptation permettant aux secteurs des pêches et de l'aquaculture marines et continentales et à leur gouvernance de se préparer aux changements défavorables, ou aux opportunités futures dans certains cas, du changement climatique. IFREMER s'intéresse dans ce projet au cas d'étude de la pêcherie pélagique du golfe de Gascogne, et en particulier aux espèces anchois et sardine. Les changements attendus sur la pêcherie de petits pélagiques concernent (I) la distributon spatiale aux différents stades de...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00470/58155/60649.pdf

Integrating a sequence of models over different life stages to predict the response of fish populations to environmental drivers : anchovy in the Bay of Biscay
Provedor de dados: 5
Autores: Huret, Martin; Petitgas, Pierre; Struski, Caroline.
Fish populations show complex life cycles with successive dependent life stages, the spatio-temporal patterns of distribution at one stage impacting distribution, growth and mortality during the next stage. Here we propose to assess the relative effect of spawning (timing, duration, fecundity and spatial distribution, resulting from adult environmental conditions over autumn and winter) and larval mortality on the resulting survival at the age of metamorphosis. We used a suite of models run sequentially: a coupled physical-biogeochemical model to provide the environmental forcing, a Dynamic Energy Budget (DEB) model for adult fish growth and reproduction (spawning timing, duration and fecundity), an Individual Based Model (IBM) for larval drift, growth and...
Tipo: Text
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00023/13449/10461.pdf

The PELGAS survey: ship-based integrated monitoring of the Bay of Biscay pelagic ecosystem
Provedor de dados: 5
Autores: Doray, Mathieu; Petitgas, Pierre; Romagnan, Jean-baptiste; Huret, Martin; Duhamel, Erwan; Dupuy, Christine; Spitz, Jerome; Authier, Matthieu; Sanchez, Florence; Berger, Laurent; Doremus, Ghislain; Bourriau, Paul; Grellier, Patrick; Masse, Jacques.
The Pélagiques Gascogne (PELGAS) integrated survey has been developed by a multidisciplinary team of Ifremer and La Rochelle University scientists since 2000, joined by commercial fishermen in 2007. Its initial focus was to assess the biomass and predict the recruitment success of anchovy in the Bay of Biscay in spring. Taking advantage of the space and versatility of R/V Thalassa II, sampling has been progressively extended to other ecosystem components. PELGAS therefore further developed the second objective of monitoring and studying the dynamic and diverse Biscay pelagic ecosystem in springtime. The PELGAS survey model has allowed for the establishment of a long-term time-series of spatially-explicit data of the Bay of Biscay pelagic ecosystem since...
Tipo: Text
Palavras-chave: Pelagic ecosystem; Integrated ecosystem monitoring survey; Marine Strategy Framework Directive; Ecosystem variability; Bay of Biscay; Fishing vessels.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00407/51801/52401.pdf

Handbook of Geostatistics in R for Fisheries and Marine Ecology
Provedor de dados: 5
Autores: 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
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00585/69732/67621.pdf

A multivariate indicator to monitor changes in spatial patterns of age-structured fish populations
Provedor de dados: 5
Autores: Petitgas, Pierre; Poulard, Jean-charles.
Quantitative analysis of the spatial patterns in age-structured fish populations provides a useful complement to stock assessment methods. The spatial distribution of an age-structured population is characterized by indicators for location, dispersion and aggregation, which are estimated from survey data. The times series of spatial indicators are organised in a 3D data structure with dimensions along indicators, age classes and years. Multi factor analysis (MFA) is applied to quantify the reproducibility in time of the multivariate structure between age classes and indicators. MFA computes the mean annual pattern over the age classes. The deviation around that pattern in each year is also quantified. A multivariate indicator that characterise the spatial...
Tipo: Text
Palavras-chave: Spatial distribution; Monitoring; CUSUM; Multi factor analysis.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6688.pdf