|
|
|
| Registros recuperados: 129 | |
|
|
| Banaru, Daniela; Mellon, Capucine; Roos, David; Bigot, Jean-louis; Souplet, Arnauld; Jadaud, Angelique; Beaubrun, P.; Fromentin, Jean-marc. |
| The Gulf of Lions ecosystemwas described using the Ecopath mass-balancemodel to characterise its structure and functioning and to examine the effects of themultispecific fisheries operating in this area. The model is composed of 40 compartments, including 1 group of seabirds, 2 groups of etaceans, 18 groups of fish, 12 groups of invertebrates, 5 groups of primary producers, detritus and discards. Input datawere based on several recurrent scientific surveys, two alternative datasets for fishing data, stock assessment outputs, stomach content analyses and published information. Results showed that the functional groups were organised into five trophic levels with the highest one represented by dolphins, anglerfish, Atlantic bluefin tuna, European hake and... |
| Tipo: Text |
Palavras-chave: Gulf of Lions; Ecopath with Ecosim; Food web; Fishing impacts. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00116/22758/20614.pdf |
| |
|
| |
|
| |
|
| |
|
|
| Fromentin, Jean-marc; Arrizabalaga, Haritz; Restrepo, Victor R; Ortiz De Urbina, J. |
| The 2004 data exploratory meeting concluded that it was no longer defensible to assess the East Atlantic and Mediterranean population using methods that assume that the catch-atsize/age is known exactly, until extensive improvements in fisheries statistics are made. For these reasons, we here investigated the potential benefits of the year-class curve analysis. The robustness and consistency of our results tend to advocate that this method is, in the present situation, a good alternative to ADAPT (among others). As a whole, the estimates of Z from the year-class curve analyses applied on the Spanish trap and Japanese long line fishery data appear indeed to be in good or excellent agreement with ADAPT outputs for the same period and same age-classes. This... |
| Tipo: Text |
Palavras-chave: Fishing and natural mortalities; Year-class curves; Stock assessment. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/00192/30325/28799.pdf |
| |
|
|
| Van Beveren, Elisabeth; Bonhommeau, Sylvain; Fromentin, Jean-marc; Bigot, Jean-louis; Bourdeix, Jean-herve; Brosset, Pablo; Roos, David; Saraux, Claire. |
| Since 2007, the ecosystem of the Gulf of Lions has shifted to a different regime, characterised by a low anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) biomass and a remarkably high sprat (Sprattus sprattus) biomass. Surprisingly, the abundance and recruitment of anchovy and sardine remained high. To understand which processes (bottom-up or top-down control, etc.) could have caused this shift, we studied the changes in body condition, growth and size and age of anchovy, sardine and sprat over 1984–1985 and 1992–2012, using data from scientific surveys. The annual age structure of anchovy and sardine was estimated using Bayesian mixture models based on size frequency data with priors on the age–length relationship derived from independent... |
| Tipo: Text |
|
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00192/30335/29917.pdf |
| |
|
|
| Granger, Victoria; Bez, Nicolas; Fromentin, Jean-marc; Meynard, Christine; Jadaud, Angelique; Merigot, Bastien. |
| Mapping diversity indices, that is estimating values in all locations of a given area from some sampled locations, is central to numerous research and applied fields in ecology. Two approaches are used to map diversity indices without including abiotic or biotic variables: (i) the indirect approach, which consists in estimating each individual species distribution over the area, then stacking the distributions of all species to estimate and map a posteriori the diversity index, (ii) the direct approach, which relies on computing a diversity index in each sampled locations and then to interpolate these values to all locations of the studied area for mapping. For both approaches, we document drawbacks from theoretical and practical viewpoints and argue... |
| Tipo: Text |
Palavras-chave: Interpolation methods; Map; Quadratic entropy; Spatial statistics; Species diversity; Species richness; Beta-diversity. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00257/36819/37060.pdf |
| |
|
|
| Fromentin, Jean-marc; Planque, Benjamin. |
| The influence of the North Atlantic Oscillation (NAO) on 2 major zooplankton species ofthe eastern North Atlantic and the North Sea, Calanus finmarchicus and C. helgolandicus (Copepoda, Calanoida), was investigated. Our results confirm that from December to April, west wind stress (WWS) intensity and temperature are strongly related to the NAO. If these results were expected, more striking were the close relationships between NAO and Calanus species abundance. Fluctuations in abundance of C. finmarchicus mainly result from the combination of 2 factors, both driven by the NAO: WWS effects on spring primary production and temperature. The case of C. helgolandicus is more complicated,as the links between this species and the NAO result from the combination of... |
| Tipo: Text |
|
| Ano: 1996 |
URL: http://archimer.ifremer.fr/doc/00033/14456/11758.pdf |
| |
|
|
| Fromentin, Jean-marc; Kell, Laurence T. |
| An integrative simulation framework was built to evaluate the consequences of variability attributable to changes in carrying capacity or the stock’s migration pattern of Atlantic bluefin tuna on the ICCAT stock assessment and management procedures. We also evaluated the performances of stock assessment methods with respect to their ability to provide good estimates of MSY, FMSY and BMSY and tested the robustness of the current ICCAT management strategy to uncertainty about the true dynamics and historical exploitation levels. The results clearly indicate that the VPA performances were seriously impaired if the long-term variations in catches are due to changes in migration/availability. There is further considerable confounding between the underlying... |
| Tipo: Text |
Palavras-chave: Thunnus thynnus; Stock assessment; VPA; Biological reference points; MSY; Management strategy; Simulation model. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00192/30295/28786.pdf |
| |
|
| |
|
| |
|
|
| Corbineau, A.; Rouyer, Tristan; Fromentin, Jean-marc; Cazelles, B.; Fonteneau, Alain; Menard, Frederic. |
| Catch data of large pelagic fish such as tuna, swordfish and billfish are highly variable ranging from short to long term. Based on fisheries data, these time series are noisy and reflect mixed information on exploitation (targeting, strategy, fishing power), population dynamics (recruitment, growth, mortality, migration, etc.), and environmental forcing (local conditions or dominant climate patterns). In this work, we investigated patterns of variation of large pelagic fish (i.e. yellowfin tuna, bigeye tuna, swordfish and blue marlin) in Japanese longliners catch data from 1960 to 2004. We performed wavelet analyses on the yearly time series of each fish species in each biogeographic province of the tropical Indian and Atlantic Oceans. In addition, we... |
| Tipo: Text |
|
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00011/12231/9029.pdf |
| |
|
|
| Brosset, Pablo; Le Bourg, Baptiste; Costalago, David; Banaru, Daniela; Van Beveren, Elisabeth; Bourdeix, Jean-herve; Fromentin, Jean-marc; Menard, Frederic; Saraux, Claire. |
| Since 2008, a severe decrease in size and body condition together with a demographic truncation has been observed in the sardine (secondarily in anchovy) population of the Gulf of Lions (NW Mediterranean Sea). In parallel, sprat biomass, which was negligible before, has increased tenfold. All of these changes have strongly affected the regional fisheries. Using trophic and isotopic data from contrasting periods of low versus high growth and condition, we investigated potential changes in diet and interspecific feeding interactions through time. Evidence of resource partitioning was found between sprat and both anchovy and sardine in 2004 and 2005. Since 2010, the isotopic niches of the 3 species have tended to overlap, suggesting higher risk of competition... |
| Tipo: Text |
Palavras-chave: Trophic ecology; Anchovy; Sardine; Sprat; Dietary overlap; NW Mediterranean. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00347/45822/45540.pdf |
| |
|
|
| Brosset, Pablo; Fromentin, Jean-marc; Van Beveren, Elisabeth; Lloret, Josep; Marques, Virginie; Basilone, Gualtiero; Bonanno, Angelo; Carpi, Piera; Donato, Fortunata; Kec, Vanja Cikes; De Felice, Andrea; Ferreri, Rosalia; Gasparevic, Denis; Giraldez, Ana; Gucu, Ali; Iglesias, Magdalena; Leonori, Iole; Palomera, Isabel; Somarakis, Stylianos; Ticina, Vjekoslav; Torres, Pedro; Ventero, Ana; Zorica, Barbara; Menard, Frederic; Saraux, Claire. |
| Small pelagic fish are among the most ecologically and economically important marine fish species and are characterized by large fluctuations all over the world. In the Mediterranean Sea, low catches and biomass of anchovies and sardines have been described in some areas during the last decade, resulting in important fisheries crises. Therefore, we studied anchovy and sardine body condition variability, a key index of population health and its response to environmental and anthropogenic changes. Wide temporal and spatial patterns were investigated by analyzing separately data from scientific surveys and fisheries in eight Mediterranean areas between 1975 and 2015. Results showed that anchovy and sardine body condition as well as maximum size in some areas... |
| Tipo: Text |
Palavras-chave: Anchovy; Sardine; Fish health; Marine monitoring. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00363/47400/47936.pdf |
| |
|
|
| Royer, Francois; Fromentin, Jean-marc. |
| This paper provides an exploratory analysis aiming to seek whether the colour of environmental noise theory could help in understanding the intriguing reproductive strategy of Atlantic bluefin tuna (BFT). A frequency-based approach based on spectral exponents, f(beta) with beta < 0, is chosen and applied on 10 biogeographical provinces covering the North Atlantic. The major BFT spawning area, i.e. the Mediterranean Sea, was the only one to display a pink power spectrum, whereas open ocean regions displayed more reddened fluctuations, i.e. greater variance at low frequencies. Environmental noise in the Mediterranean could, thus, offer more favourable characteristics on the long-term than the open ocean. The implications of these findings are discussed in... |
| Tipo: Text |
Palavras-chave: Thunnus thynnus; Spectral analysis; Spawning; Sea surface temperature; Environmental noise. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2437.pdf |
| |
|
| |
|
|
| Fonteneau, Alain; Fromentin, Jean-marc. |
| This paper develops a critical overview of the various problems and uncertainties faced in tuna stock assessment, management and conservation. This presentation is based on Atlantic tunas, but also on various tuna stocks worldwide. Tuna jisheries management is characterized by major uncertainties in the stock assessment; since these stock assessments are always done only on jishery data which are often biased. Fortunately most tuna stocks are showing a strong resistance to overfishing. These major characteristics of tuna stocks and jisheries, and the bias in the scientific analysis, are presented and discussed. As a result, many of the reference point recommended for the precautionary approach applied to jisheries are often quite inappropriate for tuna... |
| Tipo: Text |
Palavras-chave: Tunas; Precautionay approach; Atlantic; Management; Assessment. |
| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/00194/30564/28984.pdf |
| |
|
|
| Mellon, Capucine; Harmelin-vivien, Mireille; Metral, Luisa; Loizeau, Veronique; Mortreux, Serge; Roos, David; Fromentin, Jean-marc. |
| The European hake, Merluccius merluccius, is an important resource for Mediterranean fisheries. This study focuses on juvenile and adult hake feeding ecology in the Gulf of Lions, using information from scientific surveys carried out during two seasons and three years (2004-2006). Stomach content and stable isotope (ä15N, ä13C) analyses were performed, and the main factors explaining variations in ä15N were investigated using GLMs. In the Gulf of Lions, hake mostly fed on crustaceans and fish and a dominant piscivorous regime was reached at 15 cm total length. Pelagic fish (sardine, anchovy and small blue whiting) were the main source of prey (40%-80%) and cannibalism was low (<5%). The results confirmed that hake is an opportunistic feeder and also... |
| Tipo: Text |
Palavras-chave: Foodweb; GLM; Habitat; Merluccius merluccius; Predator-prey relationships; Stable isotopes; Stomach contents. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00360/47091/47016.pdf |
| |
|
|
| Ibanez, F; Fromentin, Jean-marc. |
| The typology of shapes of series (TSS) aims to gather together species having similar temporal patterns corresponding to different types of ecological behaviour. Each type of change, referred to as the ecological shape, is considered to reflect a particular demographic strategy (sudden pullulation of opportunistic species, fluctuations with environmental changes, etc.). This method which consists in the definition of four shape parameters and a classification among the series, taking into account these shape parameters, does not replace the usual statistical analyses, mainly multivariate ones, but precedes them. Such preliminary information is useful for the choice of the subsequent treatments, avoiding the need to analyse simultaneously species presenting... |
| Tipo: Text |
Palavras-chave: Times series; Ecological shape; Macrobenthic community; English Channel. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00093/20384/18050.pdf |
| |
|
|
| Fromentin, Jean-marc. |
| The aim of this study is to investigate the implications of different stock-recruitment assumptions when examining the potential of Dubrovnik’s bluefin tuna recovery plan. To do so, some Beverton and Holt relationships displaying contrasting steepness of 0.99, 0.90, 0.75 and 0.50 were applied within a simulation model. In addition to these four stock-recruitment scenarios, parental effects and stochastic variations were also considered. The main conclusion is that our ability to evaluate the consequences of the Dubrovnik agreement (as any set of management measures) relies on our capacity to predict future recruitment levels in an accurate way. Assuming a Beverton and Holt relationship with different steepness, with or without parental effects and with or... |
| Tipo: Text |
Palavras-chave: Thunnus thynnus; Management regulations; Stock-recruitment; Parental effects; Stock rebuilding; Simulation model. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00192/30296/28784.pdf |
| |
| Registros recuperados: 129 | |
|
|
|
