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| Registros recuperados: 24 | |
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| Robert, Marianne; Cortay, Aurore; Morfin, Marie; Simon, Julien; Morandeau, Fabien; Deneubourg, Jean Louis; Vincent, Benoit. |
| Knowledge about fish behavior is crucial to be able to influence the capture process and catch species composition. The rapid expansion of the use of underwater cameras has facilitated unprecedented opportunities for studying the behavior of species interacting with fishing gears in their natural environment. This technological advance would greatly benefit from the parallel development of dedicated methodologies accounting for right-censored observations and variable observation periods between individuals related to instrumental, environmental and behavioral events. In this paper we proposed a methodological framework, based on a parametric Weibull mixture model, to describe the process of escapement attempts through time, test effects of covariates and... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00663/77553/79457.pdf |
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| Capello, Manuela; Robert, Marianne; Soria, Marc; Potin, Gael; Itano, David; Holland, Kim; Deneubourg, Jean-louis; Dagorn, Laurent. |
| The rapid expansion of the use of passive acoustic telemetry technologies has facilitated unprecedented opportunities for studying the behavior of marine organisms in their natural environment. This technological advance would greatly benefit from the parallel development of dedicated methodologies accounting for the variety of timescales involved in the remote detection of tagged animals related to instrumental, environmental and behavioral events. In this paper we propose a methodological framework for estimating the site fidelity (“residence times”) of acoustic tagged animals at different timescales, based on the survival analysis of continuous residence times recorded at multiple receivers. Our approach is validated through modeling and applied on two... |
| Tipo: Text |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00275/38589/37116.pdf |
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| Merillet, Laurene; Kopp, Dorothee; Robert, Marianne; Salaun, Michele; Mehault, Sonia; Bourillet, Jean-francois; Mouchet, Maud. |
| The development of the vessel monitoring system (VMS) in the recent years has offered high-resolution data to map the distribution and intensity of fishing activities and contributed to enhancing the potential identification of fishing impacts. However, impacts could vary at very small scale and the resolution of VMS data might not be fine enough. Other proxy could be used, such as trawl marks visible on the seabed observed by underwater video or side-scan sonar to evaluate small-scale trawling effort. In the Bay of Biscay, an underwater video survey of the Nephrops norvegicus fishing ground was conducted and provided environmental characteristics such as depth and number of trawl marks at 152 transects. The relevance of observed trawl marks as a... |
| Tipo: Text |
Palavras-chave: Bay of Biscay; Fishing intensity; Sediments; Underwater video; Vessel monitoring system. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00410/52112/52854.pdf |
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| Kopp, Dorothee; Robert, Marianne; Pawlowski, Lionel. |
| In marine ecosystems, the study of trophic relationships has extensively benefited from the development of stable isotope analyses (SIA) as dietary tracers. SIA are particularly useful in elucidating the structure of deep sea food webs given the constraints involved in obtaining gut-content data from deep trawling. We used carbon and nitrogen stable isotope analyses and Stable Isotope Bayesian Ellipses in R (SIBER) and Stable Isotope Analysis in R (SIAR) routines, to determine the trophic ecology of five deep-sea fishes from the upper continental slope of the Celtic Sea. SIA made it possible to deduce some general tendencies in food-web structure and species trophic interactions and confirmed diet determined by gut-content analysis for the same species, in... |
| Tipo: Text |
Palavras-chave: Competition; Feeding habits; Mixing models; Stable isotope. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00410/52138/52940.pdf |
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| Walters, Andrea; Robert, Marianne; Cresson, Pierre; Le Bris, Hervé; Kopp, Dorothee. |
| Quantification of the physical and biological factors that influence the spatial structuring of food webs is central to inform effective resource management. We used baseline‐corrected stable isotope ratios (δ13C and δ15N) of 63 invertebrate and fish to investigate food web structure across a continental shelf gradient—the Celtic Sea Shelf in the Northeast Atlantic Ocean. Hierarchical clustering on δ13C and δ15N showed that the shelf food web is characterized by four trophic levels with trophic groups spread across pelagic and benthic trophic pathways. Four biomass‐weighted isotopic diversity metrics provided indicators on the status of the system, showing a relatively complex food web with high trophic redundancy at intermediate trophic levels suggesting... |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00693/80500/83696.pdf |
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| Calderwood, Julia; Robert, Marianne; Pawlowski, Lionel; Vermard, Youen; Radford, Zachary; Catchpole, Thomas L.; Reid, David G.. |
| As a result of the introduction of the Landing Obligation in European fisheries there is a need to equip industry with the tools and knowledge to avoid unwanted catches. Optimising fishing practices in terms of time and location fished have been acknowledged as being important in modulating catch composition. Mapping techniques used to identify and manage the spatio-temporal nature of bycatch, however, remain underutilized. Data collected on board commercial fishing vessels by observers provides an important source of information on the component of catches discarded. Using a unique dataset, combining observer data for Irish, French and British vessels operating in the Celtic Sea between 2010 and 2015, maps were developed to identify where catches of quota... |
| Tipo: Text |
Palavras-chave: Landing obligation; Discards; Consistent maps; Fishing tactics; Shiny app; Celtic sea. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00590/70162/68235.pdf |
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| Sempo, Gregory; Dagorn, Laurent; Robert, Marianne; Deneubourg, Jean-louis. |
| 1. Approximately 300 pelagic fish species naturally aggregate around floating objects (FOBs) at the surface of the oceans. Currently, more than 50% of the world catch of tropical tuna comes from the industrial tuna fisheries around drifting FOBs. Greater understanding of the complex decision-making processes leading to this aggregation pattern and the impact of the massive release of artificial FOBs by fishermen on the spatial distribution and management of tuna is needed. 2. We analyse how the interplay between social (relationships between individuals) and non-social (responses to the environment) behaviours may affect the spatial distribution of a population in a multi-FOB environment. Taking the example of tropical tunas associating with FOBs and using... |
| Tipo: Text |
Palavras-chave: Behaviour-based modelling; Bycatch; FAD; FOB; Sustainable fishery; Tuna. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00151/26275/24439.pdf |
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| Robert, Marianne; Dagorn, Laurent; Filmalter, John David; Deneubourg, Jean-louis; Itano, David; Holland, Kim. |
| Fishers have exploited the associative behavior displayed by several pelagic fish species with floating objects for decades, through the use of man-made fish aggregating devices (FADs), which facilitate the capture of such species. However, our understanding of this associative behavior and its adaptive value is poor and the scientific community is ill-equipped to provide fishery managers with science-based recommendations on the impacts of FADs on ecosystems. In an array of 13 anchored FADs around Oahu, Hawaii, USA, 72 yellowfin tuna Thunnus albacares were equipped with internal acoustic tags, which facilitated the continuous monitored of their presence and absence around each FAD using automated acoustic receivers. Data were analyzed using survival... |
| Tipo: Text |
Palavras-chave: Behavioral variability; Fish aggregating device; FAD; Yellowfin tuna; Acoustic tagging; Residence time; Survival curve. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00140/25098/23207.pdf |
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| Issac, Pierre; Robert, Marianne; Le Bris, Hervé; Rault, Jonathan; Pawlowski, Lionel; Kopp, Dorothee. |
| We used stable isotope ratio and gut content analyses to determine and compare the feeding ecology of two commercially important predator species, Lophius piscatorius and Lophius budegassa in the Celtic sea, where data concerning their trophic ecology remain sparse. This study included two areas and two size-classes, showing that anglerfish in the Celtic sea are mainly piscivorous top predators as observed in other marine waters. However, a substantial part of the diet of the fish in the small size classes consists of benthic macro-invertebrates, mainly Crustaceans. Despite the common knowledge that they are opportunistic predators that display a low degree of prey selectivity, our results suggest that the two species have different trophic niches when... |
| Tipo: Text |
Palavras-chave: Lophius; Gut content; Stable isotopes; Trophic niche; Trophic segregation; Top predator. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00395/50614/51326.pdf |
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| Capello, M.; Deneubourg, J. L.; Robert, Marianne; Holland, K. N.; Schaefer, K. M.; Dagorn, L.. |
| Estimating the abundance of pelagic fish species is a challenging task, due to their vast and remote habitat. Despite the development of satellite, archival and acoustic tagging techniques that allow the tracking of marine animals in their natural environments, these technologies have so far been underutilized in developing abundance estimations. We developed a new method for estimating the abundance of tropical tuna that employs these technologies and exploits the aggregative behavior of tuna around floating objects (FADs). We provided estimates of abundance indices based on a simulated set of tagged fish and studied the sensitivity of our method to different association dynamics, FAD numbers, population sizes and heterogeneities of the FAD-array. Taking... |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00359/47005/46935.pdf |
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| Lamothe, Julien; Larnaud, Pascal; Fiche, Marion; Robert, Marianne; Morandeau, Fabien; Vacherot, Jean-philippe; Scavinner, Marion; Simon, Julien. |
| In the context of the new European Common Fisheries Policy and in particular the Landing Obligation, this report synthesizes the trials which were carried out between 2014 and 2016 on French bottom trawlers operating in the Celtic Sea and Western Channel, to decrease their discards. All the detail of the experiments and their results are attached in the voluminous appendices. After a state of the art and various workshops organized in partnership between fishermen, equipment manufacturers and scientists, 3 basic devices were selected for the trials, according to the main fisheries: - 100 mm square meshes cylinder - SMC - (in addition to the mandatory 100mm and 120 mm square mesh panels - SMP) with or without scaring floats ; - Extension + codend in... |
| Tipo: Text |
Palavras-chave: Sélectivité; Mer Celtique; Cylindre à mailles carrées; T90; Grille à baudroie; Rejets; Églefin; Merlan; Sanglier; Selectivity; Celtic Sea; Square mesh cylinder; T90; Monkfish grid; Discards; Haddock; Whiting; Boarfish. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00403/51488/52084.pdf |
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| Gatti, Paul; Méhault, Sonia; Morandeau, Fabien; Morfin, Marie; Robert, Marianne. |
| We assessed the impact of an additional 100 mm square mesh cylinder (SMC) on the selective property of the demersal whitefish trawl in the Celtic Sea. Sea trials were conducted on board a French trawler using twin trawl rigging. We tested the effects of the position of the SMC (in front of and behind the mandatory 100 mm square mesh panel) and of the insertion of a dispersive float. Selectivity analysis revealed the 50% retention length () to be greater than the Minimum Conservation Reference Sizes regardless of species (haddock, whiting or megrim) or rigging configuration. Results did not reveal a clear effect of the SMC position. However, the insertion of the float led to a decrease in selection ranges suggesting enhanced contact probabilities with the... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00600/71236/73595.pdf |
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| Kopp, Dorothee; Robert, Marianne; Chouvelon, Tiphaine; Mehault, Sonia. |
| For the ecosystem approach to fisheries management, understanding population dynamics and ecosystem resilience in response to the landing obligation acted by the reform of the European Common Fishery Policy (CFP) is currently an important avenue of research. This study attempts to assess the impact of the new CFP on marine food webs. Total carbon and nitrogen loss induced by a discard ban were estimated for the ecosystem of the Bay of Biscay based on French At-Sea Observer data and carbon and nitrogen content of discarded fish. Changes in predator diets were estimated by comparing two Bayesian mixing models, one mimicking the current situation and the second the application of the new CFP (removing the discarded species that would be landed from the... |
| Tipo: Text |
Palavras-chave: Fishery discards; Discard ban; Bay of Biscay; Organic input; Resource use. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00308/41895/41229.pdf |
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| Reid, David G; Calderwood, Julia; Afonso, Pedro; Bourdaud, Pierre; Fauconnet, Laurence; Gonzalez-irusta, José Manuel; Mortensen, Lars O; Ordines, Francesc; Lehuta, Sigrid; Pawlowski, Lionel; Plet-hansen, Kristian S; Radford, Zachary; Robert, Marianne; Rochet, Marie-joelle; Rueda, Lucia; Ulrich, Clara; Vermard, Youen. |
| Under the Landing Obligation (LO) fishers will need to reduce or land fish that were previously discarded. In this chapter we look at how they might be able to do that by summarising a number of studies conducted in various European regions. We start by describing a series of “challenge” trials where fishers tried to reduce their discards by whatever (legal) means they thought best. In some cases, they were able to reduce unwanted catches, in others they were less successful. We also interviewed fishers not involved in the trials to ask them what they thought they could do. We explore their approaches which generally fell into three categories: more selective gear; tactical and strategic changes; and management changes. Scientific data (surveys, landings,... |
| Tipo: Text |
Palavras-chave: Challenge trials; Decision support tools; Discard avoidance; Fine scale mapping; Fish distribution; Fishers; Fishing strategies; Hot-spot maps. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00473/58428/61004.pdf |
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| Hernvann, Pierre-yves; Gascuel, Didier; Grüss, Arnaud; Druon, Jean-noël; Kopp, Dorothee; Perez, Ilan; Piroddi, Chiara; Robert, Marianne. |
| Both trophic structure and biomass flow within marine food webs are influenced by the abiotic environment and anthropogenic stressors such as fishing. The abiotic environment has a large effect on species spatial distribution patterns and productivity and, consequently, spatial co-occurrence between predators and prey, while fishing alters species abundances and food-web structure. In order to disentangle the impacts of the abiotic environment and fishing in the Celtic Sea ecosystem, we developed a spatio-temporal trophic model, specifically an Ecopath with Ecosim with Ecospace model, for the period 1985–2016. In this model, particular attention was paid to the parameterization of the responses of all trophic levels to abiotic environmental changes.... |
| Tipo: Text |
Palavras-chave: Celtic Sea; Ecosystem modeling; Habitat model; Environment; Ecopath with Ecosim and Ecospace; Primary production; Fishing impact. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00662/77419/79084.pdf |
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| Robert, Marianne; Morandeau, Fabien; Scavinner, Marion; Fiche, Marion; Patterson, Heather M.. |
| Most European fishing fleets will need to drastically reduce their unwanted catches to comply with new rules of the common fisheries policy. A more practical way to avoid increasing on-board sorting time and issues linked to storage capacity is to prevent unwanted catches in the first place. We assessed the selectivity properties of an experimental fishing gear that combined a 100 mm T90 cylinder with 130 meshes in the extension and a 100 mm T90 codend of 33 meshes (experimental gear) compared to a 100 mm diamond mesh extension and codend (control gear) during commercial trips using twin trawls. Analysis of the relative size composition of catches indicated a significantly higher escapement of small fish of several target species (e.g. Lepidorhombus... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00641/75312/75804.pdf |
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| Registros recuperados: 24 | |
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