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Auteur Sempo, G.; Dagorn, L.; Robert, M.; Deneubourg, J.-L. url  doi
openurl 
  Titre Impact of increasing deployment of artificial floating objects on the spatial distribution of social fish species Type Article scientifique
  Année 2013 Publication Revue Abrégée Journal of Applied Ecology  
  Volume 50 Numéro 5 Pages 1081-1092  
  Mots-Clés behaviour-based modelling; Bycatch; Fad; Fob; sustainable fishery; tuna  
  Résumé * 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. * 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 differential equations and stochastic simulations, we examine how, when increasing the number of FOBs, fish aggregation dynamics and the distribution of the population among patches are affected by the population size, level of sociality and the natural retentive and/or attractive forces of FOBs on individual tuna. * Our model predicts that, depending on the species' level of sociality, fish will be scattered among FOBs or aggregated around a single FOB based on the number of FOBs deployed in a homogeneous oceanic region. * For social species, we demonstrated that the total fish catch is reduced with increasing FOBs number. Indeed, for each size of population, there are a number of FOBs minimizing the total population of fish associated with FOBs and another number of FOBs maximizing the total population of associated fish. * Synthesis and applications. In terms of fisheries management, the total catch volume is directly linked to the total number of floating objects (FOBs) for non-social species, and any limit on the number of sets would then result in a limit on the total catch. For social species (e.g. tuna), however, increasing the number of FOBs does not necessarily lead to an increase in the total catch, which is a non-intuitive result. Indeed, our model shows that, for specific values of the parameters, deploying a greater number of FOBs in the water (all other parameters being constant) does not necessarily help fishermen to catch more tuna, but does increase the level of fishing effort and bycatch.  
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  Volume de collection Numéro de collection Edition  
  ISSN 1365-2664 ISBN Médium  
  Région Expédition Conférence  
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  Numéro d'Appel LL @ pixluser @ collection 265  
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Auteur Torres-Irineo, E.; Dreyfus-Leon, M.; Gaertner, D.; Salas, S.; Marchal, P. doi  openurl
  Titre Adaptive responses of tropical tuna purse-seiners under temporal regulations Type Article scientifique
  Année 2017 Publication Revue Abrégée Ambio  
  Volume 46 Numéro 1 Pages 88-97  
  Mots-Clés atlantic; behavior; Closed season; eastern pacific-ocean; eastern tropical pacific; Fisher behaviour; Fisheries management; fishing strategies; fleet dynamics; mixed fisheries; model; Purse-seine fishing; state; trawlers; Tropical tuna  
  Résumé The failure to achieve fisheries management objectives has been broadly discussed in international meetings. Measuring the effects of fishery regulations is difficult due to the lack of detailed information. The yellowfin tuna fishery in the eastern Pacific Ocean offers an opportunity to evaluate the fishers' responses to temporal regulations. We used data from observers on-board Mexican purse-seine fleet, which is the main fleet fishing on dolphin-associated tuna schools. In 2002, the Inter-American Tropical Tuna Commission implemented a closed season to reduce fishing effort for this fishery. For the period 1992-2008, we analysed three fishery indicators using generalized estimating equations to evaluate the fishers' response to the closure. We found that purse-seiners decreased their time spent in port, increased their fishing sets, and maintained their proportion of successful fishing sets. Our results highlight the relevance of accounting for the fisher behaviour to understand fisheries dynamics when establishing management regulations.  
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  Langue English Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 0044-7447 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2072  
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Auteur Amandé, M.; Ariz, J.; Chassot, E.; Molina, A.D. de; Gaertner, D.; Murua, H.; Pianet, R.; Ruiz, J.; Chavance, P. url  doi
openurl 
  Titre Bycatch of the European purse seine tuna fishery in the Atlantic Ocean for the 2003-2007 period Type Article scientifique
  Année 2010 Publication Revue Abrégée Aquatic Living Resources  
  Volume 23 Numéro 4 Pages 353-362  
  Mots-Clés atlantic Ocean; Bycatch; discards; Purse seining; Tuna fisheries  
  Résumé Bycatch of several groups of species and their characteristics are presented for the period 2003 to 2007 for the European purse seine tuna fishery operating in the Atlantic Ocean. Data were collected through French and Spanish observer programmes and represented a total of 27 trips corresponding to 2.9% coverage. Bycatch is defined as non-targeted species and small or damaged target species. Bycatch species composition, main species length, sex ratio and the fate of the most common species are presented first. Stratified ratios relative to landings of major commercial tunas were then used to estimate the total bycatch; these ratios were considered the most appropriate variable for extrapolation. Stratification was based on the fishing mode (free school vs. floating object), season (quarters) and spatial areas. The annual average bycatch was estimated at about 6400 t, corresponding to a mean annual value of 80.8 t per 1000 t of tuna landed or 7.5% of the total catch. Tunas represent 83% (67.2 t/1000 t) of the total bycatch, followed by other bony fishes (10%, 7.8 t/1000 t), billfishes (5%, 4.0 t/1000 t), sharks (1%, 0.9 t/1000 t) and rays (1%, 0.9 t/1000 t). Based on estimates of the annual bycatch, 16% was kept on board and sold in local markets.  
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  ISSN 0990-7440 ISBN Médium  
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  Numéro d'Appel LL @ pixluser @ collection 56  
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Auteur Dagorn, L.; Holland, K.N.; Filmalter, J. url  doi
openurl 
  Titre Are drifting FADs essential for testing the ecological trap hypothesis ? Type Article scientifique
  Année 2010 Publication Revue Abrégée Fisheries Research  
  Volume 106 Numéro Pages 60-63  
  Mots-Clés ecological; Fad; hypothesis; trap; Tunas  
  Résumé Because tropical tunas are known to aggregate around floating objects, it has been suggested that the large number of drifting fish aggregating devices (FADS) built and deployed by purse seiners could act as an 'ecological trap'. This hypothesis states that these networks of drifting FADS could take fish to areas where they would not normally go or retain them in places that they would otherwise leave. Because the ecological trap hypothesis was first advanced for drifting FADs, some have argued that only studies using drifting FADs can test this hypothesis. However, because working with drifting FADs is difficult, accepting this precept would preclude the scientific community from providing urgently needed information to organizations charged with management of fisheries that exploit drifting FADs. We argue that because both anchored and drifting FADs alter the natural environment, the more easily accessible anchored FADs can be used to test the ecological trap hypothesis. Also, based on a comparative scientific approach, we argue that understanding the behaviour of tunas around anchored FADs can improve our general understanding of tunas around all types of floating objects and help design new, well focused studies for drifting FADs. As anchored FADs are easier to access and offer a greater potential for research, we encourage scientists to design and conduct studies (in particular on the behaviour of fish at FADS) around the moored structures.  
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  Volume de collection Numéro de collection Edition  
  ISSN 0165-7836 ISBN Médium  
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  Numéro d'Appel LL @ pixluser @ collection 66  
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Auteur Fromentin, J.-M.; Bonhommeau, S.; Arrizabalaga, H.; Kell, L.T. url  doi
openurl 
  Titre The spectre of uncertainty in management of exploited fish stocks: The illustrative case of Atlantic bluefin tuna Type Article scientifique
  Année 2014 Publication Revue Abrégée Marine Policy  
  Volume 47 Numéro Pages 8-14  
  Mots-Clés tuna  
  Résumé  
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  Volume de collection Numéro de collection Edition  
  ISSN 0308-597x ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel LL @ pixluser @ collection 323  
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