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| Registros recuperados: 61 | |
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| Lambert, C.; Authier, M.; Doray, Mathieu; Doremus, G.; Spitz, J.; Ridoux, V.. |
| Most oceanographic systems, especially shelf ecosystems, are characterised by interannual variability in the timing, extent and intensity of their seasonal patterns. Such interannual variations have important consequences on top predator habitat preferences. Capitalising on oceanographic surveys performed every spring since 2004 in the Bay of Biscay (BoB), this study explored interannual variations in habitat preferences exhibited by five mobile top predator species: bottlenose and common dolphins, auks, fulmars and northern gannets. We expected to find species with similar habitat preferences every year or species exhibiting important variability in their habitat preferences. First, we identified with a Principal Component Analysis (PCA) three different... |
| Tipo: Text |
Palavras-chave: Habitat preference; Temporal variability; Cetaceans; Seabirds; North Atlantic; Bay of Biscay. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00431/54226/55549.pdf |
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| 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 |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00588/70035/67955.pdf |
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| Doray, Mathieu; Huret, Martin. |
| Understanding discrepancies in particular years between acoustic and Daily Egg Production Method (DEPM) estimates is essential to better understand potential bias impacting both estimates, and develop a weighting per year assessing the coherence between survey estimates, to input in stock assessment models. Several plans for collaborative work have been proposed within WGACEGG to compare acoustic and DEPM indices (WGACEGG 2013, 2015, 2016), until the inclusion of such comparative approach as a formal group ToR in 2017 (ICES, 2017). Different approaches have been adopted so far, including the comparison between two egg production estimates (DEPM BIOMAN; CUFES PELGAS) and one acoustic estimate (PELGAS), analysis of the sensitivity of each estimate to its... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00662/77411/79071.pdf |
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| 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 |
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| 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 |
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| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00445/55665/57331.pdf |
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| Huse, G.; Mackenzie, B. R.; Trenkel, Verena; Doray, Mathieu; Nottestad, L.; Oskarsson, G.. |
| The North Atlantic is a productive marine region which has supported important commercial fisheries for centuries. Many of these fisheries have exploited the pelagic species, including herring, blue whiting and tuna. Here we present data on the distribution of herring and blue whiting based on the international ecosystem survey in the Nordic Seas (IESNS), the bottom trawl survey in the Bay of Biscay and Celtic Sea (EVHOE) and the pelagic survey in the Bay of Biscay (PELGAS). We also present catch data on bluefin tuna, which has been depleted for decades but historically used to be a key predator on the other pelagic stocks during summer. The results show that there were substantial changes in the herring and blue whiting distribution during the 1990s and... |
| Tipo: Text |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00276/38675/37150.pdf |
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| 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 |
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| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00457/56841/58650.pdf |
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| Duhamel, Erwan; Doray, Mathieu; Huret, Martin; Sanchez, Florence; Lespagnol, Patrick; Doremus, Gislain; Le Bourdonnec, Pierre. |
| An acoustic survey (PELGAS) is carried out every year in the Bay of Biscay in spring onboard the French research vessel Thalassa. The objective of PELGAS survey is to study the abundance and distribution of pelagic fish in the Bay of Biscay. The main target species are anchovy and sardine but they are considered in a multi-specific context and within an ecosystemic approach as they are located in the centre of pelagic ecosystem. The Pelgas17 acoustic survey has been carried out with medium weather conditions (regular wind, low atmospheric temperatures) for the whole area, from the South of the bay of Biscay to the west of Brittany. The help of commercial vessels (two pairs of pelagic trawlers and a single one) during 18 days provided about 110 valid... |
| Tipo: Text |
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| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00398/50903/51674.pdf |
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| Duhamel, Erwan; Doray, Mathieu; Huret, Martin; Sanchez, Florence; Authier, Matthieu; Bergot, Patricia. |
| The Pelgas15 acoustic survey has been carried out with globally good weather conditions (regular low wind, medium temperatures) for the whole area, from the South of the bay of Biscay to the west of Brittany. The help of commercial vessels (two pairs of pelagic trawlers and a single one) during 18 days provided about 130 valid identification hauls instead of about 50 before 2007 when Thalassa was alone to identify echotraces. Their participation increased the precision of identification of echoes and some double hauls permitted to confirm that results provided by the two types of vessels (R/V and Fishing boats) were comparable and usable for biomass estimate purposes. These commercial vessels participated to the PELGAS survey in a very good spirit of... |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00278/38972/37513.pdf |
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| Reynal, Lionel; Doray, Mathieu; Carpentier, Andre; Druault-aubin, Vomakassi; Taquet, Marc; Lagin, Alain. |
| Deployment of anchored FADs has opened large pelagic resources to smallscale fisheries, which usually operate nearshore. The main difficulties in using FADs for fishing have now been identified. It concerns principally the design of FADs, their location, and also the type of management and exploitation. During the initial phase of FAD development, particular problems are mentioned, namely voluntary deterioration of the devices, marketing of the catches ... FADs exploitation in the area can still he optimised. The impact of FADs densities and locations (depth, distance from shore) on the concentration offish resources or on fisheryproduction is not established. Environmental impact of FADs is not weIl evaluated either. We would like to implement a workshop... |
| Tipo: Text |
Palavras-chave: DCP; Pélagique; Caraïbe; FAD; Pelagie; Caribbean. |
| Ano: 2002 |
URL: http://archimer.ifremer.fr/doc/00114/22488/20169.pdf |
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| 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 |
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| Petitgas, Pierre; Renard, Didier; Desassis, Nicolas; Huret, Martin; Romagnan, Jean-baptiste; Doray, Mathieu; Woillez, Mathieu; Rivoirard, Jacques. |
| This paper presents a novel application of the geostatistical multivariate method known as min–max autocorrelation factors (MAFs) for analysing fisheries survey data in a space–time context. The method was used to map essential fish habitats and evaluate the variability in time of their occupancy. Research surveys at sea on marine fish stocks have been undertaken for several decades now. The data are time series of yearly maps of fish density, making it possible to analyse the space–time variability in fish spatial distributions. Space–time models are key to addressing conservation issues requiring the characterization of variability in habitat maps over time. Here, the variability in fisheries survey data series is decomposed in space and time to address... |
| Tipo: Text |
Palavras-chave: MAF; Space-time; Habitat; Mapping; Sardine; Bay of Biscay. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00599/71157/69915.pdf |
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| 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 |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00055/16637/14133.pdf |
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| Cresson, Pierre; Chouvelon, Tiphaine; Bustamante, Paco; Bănaru, Daniela; Baudrier, Jerome; Le Loch, Francois; Mauffret, Aourell; Mialet, Benoit; Spitz, Jérome; Wessel, Nathalie; Briand, Marine; Denamiel, Margaux; Doray, Mathieu; Guillou, Gaël; Jadaud, Angelique; Lazard, Coline; Noûs, Camille; Prieur, Solène; Rouquette, Manuel; Saraux, Claire; Serre, Sandrine; Timmerman, Charles-andre; Verin, Yves; Harmelin-vivien, Mireille. |
| Investigating the drivers of fish assemblage trophic structure is a critical question, in order to better understand ecosystem functioning, predict the effects of perturbations and implement integrated management of exploited marine ecosystems. Ecosystemic surveys enabled the determination of the trophic structure of the fish assemblages in three French marine ecosystems, namely the Eastern English Channel, the Bay of Biscay and the Gulf of Lions, through the simultaneous collection of qualitative (stable isotopes and energy content) and quantitative (biomass) data. In the Bay of Biscay and in the Gulf of Lions, pelagic primary production supported at least 80% of the fish biomass production, and explained the dominance of pelagic species, but with... |
| Tipo: Text |
Palavras-chave: Fish community; Trophodynamics; Food webs; Benthic-pelagic coupling. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00629/74120/73562.pdf |
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| 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 |
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| Mahevas, Stephanie; Trenkel, Verena; Doray, Mathieu; Peyronnet, Arnaud. |
| Several factors affect trawl catchability: (i) gear and vessel technical characteristics, (ii) anthropogenic factors, and (iii) biological factors. The objectives of this study were to assess the relative contribution of each factor to variations in hake (Merluccius merluccius) landings by the French trawler fleet operating on the shelf of the northern Bay of Biscay (ICES Subdivision VIIIa). Using generalized linear models, the impact of technical and anthropogenic factors was evaluated using landings per unit effort (lpue) obtained from logbooks. Variations in hake lpue were explained primarily by anthropogenic factors. For studying the biological components of catchability, the results of a scientific trawl survey in July 2006 involving three similar... |
| Tipo: Text |
Palavras-chave: Accessibility; Beam trawl; Catchability; Fishing power; GLMM; Spatial distribution. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00021/13244/10287.pdf |
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| Registros recuperados: 61 | |
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