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Auteur Chassot, E.; Duplisea, D.; Hammill, M.; Caskenette, A.; Bousquet, N.; Lambert, Y.; Stenson, G. url  doi
openurl 
  Titre Role of predation by harp seals Pagophilus groenlandicus in the collapse and non-recovery of northern Gulf of St. Lawrence cod Gadus morhua Type Article scientifique
  Année 2009 Publication Revue Abrégée Mar. Ecol.-Prog. Ser.  
  Volume 379 Numéro Pages 279-297  
  Mots-Clés cod; functional response; harp seal; model; predation; recovery  
  Résumé A statistical catch-at-age model was developed to assess the effects of predation by the northwest Atlantic harp seal population on northern Gulf of St. Lawrence cod by estimating the relative importance of different sources of mortality that affected the stock during a period of collapse and non-recovery. Cod recruitment at age 1 is modeled via a non-linear stock-recruitment relationship based on total egg production and accounts for changes in female length-at-maturity and cod condition. Natural mortality other than seal predation also depends on cod condition used as an integrative index of changes in environmental conditions. The linkage between seals and cod is modeled through a multi-age functional response that was derived from the reconstruction of the seal diet using morphometric relationships and stomach contents of more than 200 seals collected between 1998 and 2001. The model was fitted following a maximum likelihood estimation approach to a scientific survey abundance index (1984 to 2006). Model results show that the collapse of the northern Gulf of St. Lawrence cod stock was mainly due to the combination of high fishing mortality rates and poor environmental conditions in the early to mid-1990s contributing to the current state of recruitment overfishing. The increase in harp seal abundance during 1984 to 2006 was reflected by an increase in predation mortality for the young cod age-groups targeted by seals. Although current levels of predation mortality affect cod spawning biomass, the lack of recovery of the NGSL cod stock seems mainly due to the very poor recruitment.  
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  Langue Eng Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 0171-8630 ISBN Médium  
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  Numéro d'Appel LL @ pixluser @ collection 15  
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Auteur Travers, M.; Shin, Y.-J.; Jennings, S.; Machu, E.; Huggett, J.A.; Field, J.G.; Cury, P. url  doi
openurl 
  Titre Two-way coupling versus one-way forcing of plankton and fish models to predict ecosystem changes in the Benguela Type Article scientifique
  Année 2009 Publication Revue Abrégée Ecological Modelling  
  Volume 220 Numéro 21 Pages 3089-3099  
  Mots-Clés Benguela upwelling; Ecem 07; End-to-end approach; food web; marine; Marine ecosystem model coupling; Predation  
  Résumé 'End-to-end' models have been adopted in an attempt to capture more of the processes that influence the ecology of marine ecosystems and to make system wide predictions of the effects of fishing and climate change. Here, we develop an end-to-end model by coupling existing models that describe the dynamics of low (ROMS-N(2)P(2)Z(2)D(2)) and high trophic levels(OSMOSE). ROMS-N(2)P(2)Z(2)D(2) is a biogeochemical model representing phytoplankton and zooplankton seasonal dynamics forced by hydrodynamics in the Benguela upwelling ecosystem. OSMOSE is an individual-based model representing the dynamics of several species of fish, linked through opportunistic and size-based trophic interactions. The models are coupled through a two-way size-based predation process. Plankton provides prey for fish, and the effects of predation by fish on the plankton are described by a plankton mortality term that is variable in space and time. Using the end-to-end model, we compare the effects of two-way coupling versus one-way forcing of the fish model with the plankton biomass field. The fish-induced mortality on plankton is temporally variable, in part explained by seasonal changes in fish biomass. Inclusion of two-way feedback affects the seasonal dynamics of plankton groups and usually reduces the amplitude of variation in abundance (top-down effect). Forcing and coupling lead to different predicted food web structures owing to changes in the dominant food chain which is supported by plankton (bottom-up effect). Our comparisons of one-way forcing and two-way coupling show how feedbacks may affect abundance, food web structure and food web function and emphasise the need to critically examine the consequences of different model architectures when seeking to predict the effects of fishing and climate change.  
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  ISSN 0304-3800 ISBN Médium  
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  Numéro d'Appel LL @ pixluser @ collection 29  
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Auteur Queiros, Q.; Fromentin, J.-M.; Astruc, G.; Bauer, R.K.; Saraux, C. doi  openurl
  Titre Dolphin predation pressure on pelagic and demersal fish in the northwestern Mediterranean Sea Type Article scientifique
  Année 2018 Publication Revue Abrégée Mar. Ecol.-Prog. Ser.  
  Volume 603 Numéro Pages 13-27  
  Mots-Clés Anchovy; artisanal fisheries; bottle-nosed dolphins; Bottlenose dolphin; cetaceans reveals; delphinus-delphis; European hake; Gulf of Lions; longline fisheries; marine ecosystem; Predation pressure; Sardine; stenella-coeruleoalba; Striped dolphin; striped-dolphin; Top-down effect; trophic cascades; tursiops-truncatus  
  Résumé Sardine Sardina pilchardus, anchovy Engraulis encrasicolus and European hake Merluccius merluccius represent a significant part of the commercial landings in the Gulf of Lions (northwestern Mediterranean Sea). However, their stocks have shown severe declines during the last decades due to fishing pressure and/or environmental changes. The aim of this study was to estimate the current predation pressure of bottlenose dolphins Tursiops truncatus and striped dolphins Stenella coeruleoalba – which are abundant in the area-on sardine, anchovy and hake. To do so, we developed an original approach based on several data sets and models (aerial surveys, stomach contents, allometric and stock assessment models) and Monte Carlo simulations to incorporate various sources of uncertainty due to data limitations. Despite the uncertainties, the results showed that dolphin predation pressure on sardine and anchovy was extremely low in the Gulf of Lions (all simulations <0.5 % of the available stock), indicating little impact of dolphins on those populations. However, significant predation pressure on hake (median value: 23 %) was detected, a value which might have doubled in the last 30 yr because of hake overfishing. Overexploitation has thus reinforced the natural mortality of hake due to dolphin predation, but this predation pressure remains 2 to 3 times lower than that exerted by fisheries.  
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  Langue English Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 0171-8630 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2429  
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Auteur McKenzie, D.J.; Belao, T.C.; Killen, S.S.; Rantin, F.T. doi  openurl
  Titre To boldly gulp: standard metabolic rate and boldness have context-dependent influences on risk-taking to breathe air in a catfish Type Article scientifique
  Année 2015 Publication Revue Abrégée J. Exp. Biol.  
  Volume 218 Numéro 23 Pages 3762-3770  
  Mots-Clés african catfish; animal personality; Bimodal respiration; clarias-gariepinus; ecological consequences; Energy metabolism; european sea bass; Hypoxia; individual variation; oncorhynchus-mykiss; Personality; personality-traits; predation risk; Respiratory partitioning; Risk-taking; wild-type zebrafish  
  Résumé The African sharptooth catfish Clarias gariepinus has bimodal respiration, it has a suprabranchial air-breathing organ alongside substantial gills. We used automated bimodal respirometry to reveal that undisturbed juvenile catfish (N=29) breathed air continuously in normoxia, with a marked diurnal cycle. Air breathing and routine metabolic rate (RMR) increased in darkness when, in the wild, this nocturnal predator forages. Aquatic hypoxia (20% air saturation) greatly increased overall reliance on air breathing. We investigated whether two measures of risk taking to breathe air, namely absolute rates of aerial O-2 uptake ((M) over dotO(2), air) and the percentage of RMR obtained from air (% (M) over dotO(2), air), were influenced by individual standard metabolic rate (SMR) and boldness. In particular, whether any influence varied with resource availability (normoxia versus hypoxia) or relative fear of predation (day versus night). Individual SMR, derived from respirometry, had an overall positive influence on (M) over dotO(2), air across all contexts but a positive influence on % (M) over dotO(2), air only in hypoxia. Thus, a pervasive effect of SMR on air breathing became most acute in hypoxia, when individuals with higher O-2 demand took proportionally more risks. Boldness was estimated as time required to resume air breathing after a fearful stimulus in daylight normoxia (T-res). Although T-res had no overall influence on (M) over dotO(2), air or % (M) over dotO(2), air, there was a negative relationship between Tres and % (M) over dotO(2), air in daylight, in normoxia and hypoxia. There were two Tres response groups, 'bold' phenotypes with Tres below 75 min (N= 13) which, in daylight, breathed proportionally more air than 'shy' phenotypes with Tres above 115 min (N= 16). Therefore, individual boldness influenced air breathing when fear of predation was high. Thus, individual energy demand and personality did not have parallel influences on the emergent tendency to take risks to obtain a resource; their influences varied in strength with context.  
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  Langue English Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 0022-0949 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 1429  
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Auteur Potier, M.; Ménard, F.; Benivary, H.D.; Sabatié, R. url  doi
openurl 
  Titre Lenght and weight estimates from diagnostic hard part structures of fish, crustacea and cephalopods forage species in the western Indian Ocean Type Article scientifique
  Année 2011 Publication Revue Abrégée Environmental Biology of Fishes  
  Volume Numéro Pages  
  Mots-Clés Analyse Quantitative; Contenu Stomacal; Espece Pelagique; Poisson Marin; predation; Relation Taille Poids; Structure Trophique  
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  Volume de collection Numéro de collection Edition  
  ISSN 1573-5133 ISBN Médium  
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  Notes (up) Approuvé pas de  
  Numéro d'Appel LL @ pixluser @ collection 159  
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