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A Methodological Framework to Estimate the Site Fidelity of Tagged Animals Using Passive Acoustic Telemetry ArchiMer
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...
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Ano: 2015 URL: https://archimer.ifremer.fr/doc/00275/38589/37116.pdf
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Are trawl marks a good indicator of trawling pressure in muddy sand fishing grounds? ArchiMer
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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Characterization of food web structure of the upper continental slope of the Celtic Sea highlighting the trophic ecology of five deep-sea fishes ArchiMer
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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Impact of increasing deployment of artificial floating objects on the spatial distribution of social fish species ArchiMer
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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Intra-individual behavioral variability displayed by tuna at fish aggregating devices (FADs) ArchiMer
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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Investigating feeding ecology of two anglerfish species, Lophius piscatorius and Lophius budegassa in the Celtic Sea using gut content and isotopic analyses ArchiMer
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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Population assessment of tropical tuna based on their associative behavior around floating objects ArchiMer
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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Projet CELSELEC. Amélioration de la sélectivité des chalutiers hauturiers en mer Celtique ArchiMer
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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Some expected impacts of the Common Fishery Policy on marine food webs ArchiMer
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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The aggregation of tuna around floating objects: What could be the underlying social mechanisms? ArchiMer
Robert, Marianne; Dagorn, Laurent; Deneubourg, Jean Louis.
Several empirical and theoretical studies have shown how the exploitation of food sources, the choice of resting sites or other types of collective decision-making in heterogeneous environments are facilitated and modulated by social interactions between conspecifics. It is well known that many pelagic fishes live in schools and that this form of gregarious behavior provides advantages in terms of food intake and predator avoidance efficiency. However, the influence of social behavior in the formation of aggregations by tuna under floating objects (FOBs) is poorly understood. In this work, we investigated the collective patterns generated by different theoretical models, which either include or exclude social interactions between conspecifics, in the...
Tipo: Text Palavras-chave: Models Of Aggregation; Monte Carlo multi-agents simulations; Fish Aggregating Devices; Social Behavior.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00195/30638/29091.pdf
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The Best Way to Reduce Discards Is by Not Catching Them! ArchiMer
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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Trophic ecology of large gadiforms in the food web of a continental shelf ecosystem ArchiMer
Day, Louise; Kopp, Dorothee; Robert, Marianne; Le Bris, Hervé.
Human activities affect continental shelves, especially due to the harvest of living marine resources. Understanding their functioning and dynamics has become a growing concern in recent decades, especially through use of trophic modelling approaches. Studying the feeding ecology of key component species also improves this understanding by providing accurate information on trophic processes, particularly the dependence on trophic pathways. This study focuses on the trophic ecology of four large gadiforms (cod, haddock, whiting and hake) found on the continental shelf of the Celtic Sea. The study combines information on recently ingested prey (gut content analysis) and a more integrated indicator of food sources (stable isotope analysis). Two size classes...
Tipo: Text Palavras-chave: Celtic Sea; Feeding; Gut content; Stable isotopes; Ontogeny; Habitat comparison.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00486/59742/62839.pdf
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Trophic models: What do we learn about Celtic Sea and Bay of Biscay ecosystems? ArchiMer
Moullec, Fabien; Gascuel, Didier; Bentorcha, Karim; Guenette, Sylvie; Robert, Marianne.
Trophic models are key tools to go beyond the single-species approaches used in stock assessments to adopt a more holistic view and implement the Ecosystem Approach to Fisheries Management (EAFM). This study aims to: (i) analyse the trophic functioning of the Celtic Sea and the Bay of Biscay, (ii) investigate ecosystem changes over the 1980–2013 period and, (iii) explore the response to management measures at the food web scale. Ecopath models were built for each ecosystem for years 1980 and 2013, and Ecosim models were fitted to time series data of biomass and catches. EcoTroph diagnosis showed that in both ecosystems, fishing pressure focuses on high trophic levels (TLs) and, to a lesser extent, on intermediate TLs. However, the interplay between local...
Tipo: Text Palavras-chave: Ecosystem Approach to Fisheries Management (EAFM); Bay of Biscay; Celtic Sea; Ecopath with Ecosim; EcoTroph; Trophic indicators.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00377/48771/49169.pdf
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Underwater video offers new insights into community structure in the Grande Vasière (Bay of Biscay) ArchiMer
Merillet, Laurene; Robert, Marianne; Salaun, Michele; Schuck, Lucie; Mouchet, Maud; Kopp, Dorothee.
Based on towed underwater videos, diversity patterns and their main environmental and anthropogenic drivers were assessed in the “Grande Vasière” (northeast Bay of Biscay), one of the main French fishing grounds. The density of bentho-demersal megafauna was recorded along 152 transects in this area in 2014. The highest number of taxa and densities were observed on the external margin of the Grande Vasière, in deep areas with low fishing intensity. The highest levels of taxa evenness were located on the central and coastal parts that are shallower and exposed to medium to high trawling intensity. Multivariate analysis identified four different communities driven by fishing intensity, depth, sediment type and bottom current speed. We distinguished three...
Tipo: Text Palavras-chave: Biodiversity patterns; Indicator species; Fishing and environmental variables.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00441/55261/56796.pdf
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Using underwater video to assess megabenthic community vulnerability to trawling in the Grande Vasière (Bay of Biscay) ArchiMer
Merillet, Laurene; Mouchet, Maud; Robert, Marianne; Salaun, Michele; Schuck, Lucie; Vaz, Sandrine; Kopp, Dorothee.
Trawling activities are considered to be one of the main sources of disturbance to the seabed worldwide. We aimed to disentangle the dominance of environmental variations and trawling intensity in order to explain the distribution of diversity patterns over 152 sampling sites in the French trawl fishing-ground, the Grande Vasière. Using a towed underwater video device, we identified 39 taxa to the finest taxonomic level possible, which were clustered according to their vulnerability to trawling disturbance based on functional traits. Using generalized linear models, we investigated whether the density distribution of each vulnerability group was sensitive to trawling intensity and habitat characteristics. Our analyses revealed a structuring effect of depth...
Tipo: Text Palavras-chave: Bay of Biscay; Biodiversity; Bottom trawl; Fishing; Underwater video; Vulnerability.
Ano: 2018 URL: http://archimer.ifremer.fr/doc/00406/51741/52436.pdf
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