Éditeur(s) : The National Academy of Sciences of the USA
Résumé : The patterns of variations in fisheries time series are known to result from a complex combination of species and fisheries dynamics all coupled with environmental forcing (including climate, trophic interactions, etc.). Disentangling the relative effects of these factors has been a major goal of fisheries science for both conceptual and management reasons. By examining the variability of 169 tuna and billfish time series of catch and catch per unit effort (CPUE) throughout the Atlantic as well as their linkage to the North Atlantic Oscillation (NAO), we find that the importance of these factors differed according to the spatial scale. At the scale of the entire Atlantic the patterns of variations are primarily spatially structured, whereas at a more regional scale the patterns of variations were primarily related to the fishing gear. Furthermore, the NAO appeared to also structure the patterns of variations of tuna time series, especially over the North Atlantic. We conclude that the patterns of variations in fisheries time series of tuna and billfish only poorly reflect the underlying dynamics of these fish populations; they appear to be shaped by several successive embedded processes, each interacting with each other. Our results emphasize the necessity for scientific data when investigating the population dynamics of large pelagic fishes, because CPUE fluctuations are not directly attributable to change in species' abundance.
Proceedings of the National Academy of Sciences of the United States of America (0027-8424) (The National Academy of Sciences of the USA), 2008-04 , Vol. 105 , N. 14 , P. 5420-5425

Droits : 2008 by The National Academy of Sciences of the USA
http://archimer.ifremer.fr/doc/2008/publication-3984.pdf
DOI:10.1073/pnas.0709034105
http://archimer.ifremer.fr/doc/00000/3984/

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
Giant earthquake (moment magnitude M-w >= 8.5) forecasts for subduction zones have been empirically related to both tectonic stresses and geometrical irregularities along the subduction interface. Both of these controls have been suggested as able to tune the ability of rupture to propagate laterally and, in turn, exert an important control on giant earthquake generation. Here we test these hypotheses, and their combined influence, by compiling a dataset of trench fill thickness (a proxy for smoothing of subducting plate relief by sediment input into the subduction channel) and upper plate strain (a proxy for the tectonic stresses applied to the subduction interface) for 44 segments of the global subduction network. We statistically compare relationships between upper plate strain, trench sediment thickness and maximal earthquake magnitude. We find that the combination of both large trench fill (>= 1 km) and neutral upper plate strain explains spatial patterns of giant earthquake occurrence to a statistically significant degree. In fact, the concert of these two factors is more highly correlated with giant earthquake occurrence than either factor on its own. Less frequent giant earthquakes of lower magnitude are also possible at subduction zones with thinner trench fill and compressive upper plate strain. Extensional upper plate strain and trench fill < 0.5 km appear to be unfavorable conditions, as giant earthquakes have not been observed in these geodynamical environments during the last 111 years. Citation: Heuret, A., C. P. Conrad, F. Funiciello, S. Lallemand, and L. Sandri (2012), Relation between subduction megathrust earthquakes, trench sediment thickness and upper plate strain, Geophys. Res. Lett., 39, L05304, doi: 10.1029/2011GL050712.
ISSN: 0094-8276

hal-00745636
https://hal.archives-ouvertes.fr/hal-00745636
https://hal.archives-ouvertes.fr/hal-00745636/document
https://hal.archives-ouvertes.fr/hal-00745636/file/heuretGRL2012.pdf
DOI : 10.1029/2011GL050712

Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999
Résumé : In 1998, the French and Spanish tuna-boat owners associations have volentarily reconducted the Atlantic tuna protection plan (also called moratorium) initiated the previous year. This plan which has become an iccat recommendation for 1999, consists mainly in preventing fishing on floating objects (logs) and in having observers on board tuna purse seiners. Data collected by these observers and landing statistics allow to draw preliminary conclusions on some effects of the protection plan, on the fleets and on the Atlantic tuna stocks. Largely respected, the moratorium has led to a spatial redistribution of the fishing effort, an important reduction of the proportion of sets on logs and a decrease of the landings by one third compared to those realised the years before during the same months, particularily for the skipjack and the bigeye tunas. Moreover, data collected allow to calculate catch rates for a number of by-catch species in the purse seine fishery.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00042/15313/12660.pdf
http://archimer.ifremer.fr/doc/00042/15313/

Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999
Résumé : The original baitboat fishing technique using a permanent association between the fishing boat and the tuna school has been developed by the baitboat fleet of Dakar, Senegal and is also in use in the Canary Islands. This new fishing technique, the result of 20 years of improvements still on, has induced a dramatic increase of the catch yields which, in turn, has sustained the survival and even a recent development of the fleet. This technique is based on the aggregating behaviour of tropical tunas. However, it contains a dynamic component which is not found in tuna fishing on drifting or anchored fads. The specifications of the method, its refinement over the years and its main consequences for the fishery are described together with the school exchanges between baitboats over months even from one year to the next. Based on the analysis of 1228 recoveries from 5500 tagged fish, tuna movements among associated schools, between associated schools and free schools fished by purse seiners and movements in and out of the baitboat fishing grounds help to better understand the dynamics of tunas and schools of this peculiar tuna association. These data show a very high recovery rate, a remarkable tuna fidelity to the original school for all species, a small number of recoveries within the purse seine catch as well as the rare tuna movements outside the baitboat area. The study highlights the complexity and the numerous consequences of tuna and school behaviour.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00042/15304/12637.pdf
http://archimer.ifremer.fr/doc/00042/15304/

Éditeur(s) : Ecole Nationale Supérieure Agronomique de Rennes (ENSAR)
Résumé : Artificial Fish Aggregating Devices (FADs) are known to concentrate tropical tunas. This aggregative behaviour drastically increases the vulnerability of these species to fishing. Alternatively, FADs can be used as oceanic observatories to study the aggregative behaviour of large pelagic fish. We conducted sea surveys in Martinique (Lesser Antilles) to i) establish a typology of the pelagic fish aggregations found around moored FADs ii) study their relations with their biotic and abiotic environment and the local fishery. The mean biomass of large pelagic fish aggregations was also estimated to provide scientific inputs to achieve a sustainable management of the moored FAD fishery. The first part presents the background of the study. We introduce the regional pelagic ecosystem, the aggregative behaviour of pelagic fish around FADs and the Martinican moored FAD fishery. The second part begins with a presentation of the conceptual framework of the study: the hierarchy theory. Observation scales and survey methodology are therefore described. Repeated echosounder surveys run in a star pattern were conducted around 2 moored FADs, in combination with underwater video observations, classical fishing experiments and CTD profiles. In the third part, the elements of the [moored FAD ¿ pelagic fish - environment - fishing] system and their interactions are numerically characterised in the vertical plane. The main type of pelagic fish aggregation was a large aggregation distributed in sub-surface (40-100 m) within a radius of 400 m of the FAD. This aggregation was mostly made of 60 cm FL blackfin tunas (Thunnus atlanticus). It appeared at sunrise and mostly spread away in the late afternoon. It was observed during all daytime surveys. The average density and the vertical structure of the micronektonic sound scattering layers (SSLs) were assessed locally around a FAD for 48h cycles. These SSLs descriptors showed positive correlation with the size and the abundance of the sub-surface tuna aggregation. Whereas this aggregation accounted for about 95% of the total biomass aggregated around a moored FAD, it was nearly unexploited by the local commercial fishermen. The fourth part focuses on the sub-surface tuna aggregation. A high variability of the spatial distribution of the aggregation was evidenced in the horizontal plane at daily, day to day and monthly temporal scales. These variations were related to fluctuations of the global abundance of the aggregation. The daytime average density of sub-surface tuna was modelled as a function of the distance to FAD, within an advection-diffusion framework. Based on these results, a universal kriging model was designed to assess the mean maximum daily biomass of the sub-surface tuna aggregation. This mean biomass estimate yielded 11 tons with an estimation error of 26%. To conclude, we present a hierarchical organization in space and time of a sub-surface tuna population distributed within a network of moored FADs, from micro to meso-scale. We suggest that the spatial distribution of tunas can be explained from fine to coarse-scales by behavioural processes (self-organization, feeding, aggregative behaviour) whereas their spatial distribution is mainly forced by environmental processes at broader scales.
L'utilisation de Dispositifs de Concentration de Poissons permet de provoquer la formation de larges agrégations de thonidés autour de dispositifs artificiels, ce qui augmente considérablement la vulnérabilité de ces ressources vis-à-vis de l'exploitation halieutique. Les DCP peuvent également être utilisés en tant qu'observatoires océaniques, afin d'étudier le comportement agrégatif du macronecton pélagique. Nous avons ainsi réalisé des observations autour de DCP ancrés en Martinique, afin de définir une typologie des agrégations de macronecton et de étudier leurs relations avec leur environnement biotique, abiotique et l'exploitation halieutique locale. Nous avons ensuite estimé la biomasse moyenne de macronecton agrégé autour d'un DCP ancré, afin de fournir des éléments scientifiques nécessaires à une gestion durable de ces ressources. La première partie présente le contexte de l'étude i.e. l'écosystème pélagique régional, le phénomène d'agrégation du macronecton autour des DCP et la pêche associée aux DCP ancrés en Martinique. La deuxième partie introduit la théorie de la hiérarchie qui a fourni le cadre conceptuel de l'étude et présente les échelles et méthodes d'observation. Le principal outil d'observation est un échosondeur scientifique, mis en oeuvre le long de parcours en étoile autour du DCP. Les prospections acoustiques ont été combinées à des observations vidéo sous marines, des pêches expérimentales et un suivi in-situ de l'environnement abiotique. La troisième partie présente une typologie des éléments constituant le système [DCP ancré - macronecton - environnement - pêche] dans le plan vertical et précise leurs interactions. Le type d'agrégation de macronecton dominant est une grande agrégation composée d'une majorité de thons noirs (Thunnus atlanticus) de taille moyenne (60 cm) distribuée en sub-surface (40-100 m), dans un rayon de 300 m autour de la tête des DCP. Cette agrégation se forme au lever du soleil et se disperse presque totalement dans l'après midi. Elle a été observée de jour lors de toutes les campagnes. Une corrélation positive entre la densité et la structure moyenne des couches micronectoniques diurnes évaluée localement autour du DCP au cours de 48 h et les dimensions et l'énergie acoustique de l'agrégation de thons de subs-surface a été mise en évidence. Malgré le fait que cette agrégation représente en moyenne 95 % de l'énergie acoustique du macronecton autour des DCP, elle est presque inexploitée par les pêcheurs artisans locaux. La quatrième partie met en évidence les fortes variations conjointes de la distribution spatiale dans le plan horizontal de la densité de l'agrégation de thons de sub-surface et de son abondance globale. Ces variations ont été observées au cours du cycle nycthéméral et aux échelles inter-journalières et mensuelles. La distribution spatiale moyenne de la densité diurne de l'agrégation en fonction de la distance au centre de gravité de l'agrégation est cependant très stable et peut être modélisée au moyen d'une équation d'advection-diffusion. Un modèle de krigeage universel, utilisant les résultats du modèle d'advection-diffusion, a permis d'évaluer la biomasse maximale journalière moyenne de l'agrégation de thons de sub-surface à une dizaine de tonnes, avec un coefficient de variation d'estimation de 26%. Nous proposons une représentation hiérarchique synthétique de la distribution spatiale d'une sous-population de thons dans un réseau de DCP ancrés de la micro à la méso-échelle. Nous suggérons que la distribution spatiale des thons est déterminée principalement à l'échelle fine (100m-1km) et à l'échelle grossière (1-10 km) par des processus comportementaux (auto-organisation, agrégation, nutrition) et par des processus environnementaux à échelle plus large.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2006/these-1735.pdf
http://archimer.ifremer.fr/doc/2006/sup-1735.pdf
http://archimer.ifremer.fr/doc/00000/1735/

Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999
Résumé : From 1972, when Solomon Taiyo Limited (stl) started a pole-and-line fishing operation, to 1980, stl vessels had been catching tuna almost exclusively from surface free-swimming schools. In 1981, a fad programme group purse-seining fishing operation, using the Filipino "payao" model, was put in place. Results were excellent and STL vessels quickly adapted their fishing methods to make the best use of fads. STL slightly modified the original payao design to better suit its own needs and nowadays, about 90% of the group purse seine catch, i.e. 5,800 t annually, and around 60-70% of the pole-and-line catch, i.e. about 15,000 t annually, come from fad fishing. fads bring benefits not only to stl but also to the rural communities of the region. For stl, it allows savings on the operational costs, especially those of pole-and-line fishing operations, reduction of searching time and a better regularity of fish landings. For the rural communities, it gives better returns to bait-ground owners through royalties paid by stl for their baitfishing boats and it allows local fishing communities (known as canoe-fishermen) to increase their catches using fishing methods (artisanal) such as trolling and midwater handlines set around fads. This provides fish for family consumption and a source of income from fish sold. Overall, the importance of fads to stl's fishing operation, and therefore to the local economy as a whole, is high, although no precise value can be attached to it.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00042/15307/12643.pdf
http://archimer.ifremer.fr/doc/00042/15307/

Éditeur(s) : HAL CCSD
Résumé : The field campaign on the Sète coast deployed during the winter 2009 was used to understand the hydrodynamics on a double barred beach in the surf zone during storm periods. The large set of measurements collected at several position and depth were also useful to improve the 3D circulation model Symphonie that takes into account the atmospherics and wave forcings. Once implemented on the beach and supplemented with some additional parameterizations concerning the roller effects and the bottom friction, the model was tuned and validated in the surf zone. The role of the different processes was then analysed. Thus, the roller and the bottom friction are of primary importance in the dynamics of the circulation. Thanks to its 3D nature and once associated with a sediment transport model and a morphodynamic model, Symphonie will offer a good representation of the sediment transport.
Coastal Dynamics 2013
Arcachon, France

hal-00855035
https://hal.archives-ouvertes.fr/hal-00855035

Éditeur(s) : HAL CCSD Oxford University Press (OUP): Policy P - Oxford Open Option A Oxford University Press (OUP)
Résumé : International audience
It is well known that sedimentary rocks having same porosity can have very different pore size distribution. The pore distribution determines many characteristics of the rock, among which its transport properties are often the most useful. Multifractal analysis is a powerful tool that is increasingly used to characterize the pore space. In this study, we performed multifractal analysis of pore distribution on simulated sedimentary rocks using the relaxed bidisperse ballistic deposition model (RBBDM). The RBBDM can generate a 3-D structure of sedimentary rocks of variable porosity by tuning the fraction p of particles of two different sizes. We also performed multifractal analysis on two samples of real sedimentary rock to compare with the simulation studies. One sample, an oolitic limestone is of high porosity (40 per cent) while the other is a reefal carbonate of low porosity, around 7 per cent. 2-D sections of X-ray microtomographs of the real rocks were stacked sequentially to reconstruct the real rock specimens. Both samples show multifractal character. The results from analysis of real rock agree quite well with the simulated structure of low porosity. The simulated rock of high porosity showed a weak multifractal nature though the real rock sample of similar porosity was found to be strongly multifractal. We propose a ‘structure parameter’ ξ which is a function of porosity and the generalized dimensions, and controls the transport properties of the rock.
ISSN: 0956-540X

hal-01174142
https://hal.archives-ouvertes.fr/hal-01174142
DOI : 10.1093/gji/ggu417

Éditeur(s) : HAL CCSD Royal Society of Chemistry
Résumé : International audience
A versatile sol-gel route has been developed for the preparation of hierarchical porous silica membrane material with highly dispersed platinum nanoparticles (Pt-NPs). The outstanding feature of the "one pot" synthesis developed in this work lies in the successful preparation of a stable complex suspension made of silica sol, multi-scale porogens and Pt nanoparticles. The multi-scale porogens were based on non-ionic triblock copolymers and aqueous latex suspension to create mesopores and macropores, respectively, with finely tuned pore size and organization. For further functionalization of the membranes, Pt nanoparticles of about 4 nm in diameter were prepared by irradiating with microwaves (MW) the Pt precursors added in the starting suspension. This original path is suggested to enable a pre-organization of Pt nanoparticles in the ordered mesoporous structure. The suspensions were then deposited as thin films on either dense or macroporous supports, and further thermally treated at 450°C to remove the porogen units. Hierarchical porous layers composed of micropores (<2 nm), ordered mesopores (∼4 nm) and macropores (∼70 nm) with or without Pt were prepared and characterized. The resulting membranes are foreseen to exhibit great potential as multifunctional membranes for gas separation coupled with catalytic reaction. © The Royal Society of Chemistry 2008.
ISSN: 0959-9428

hal-01680586
https://hal.univ-antilles.fr/hal-01680586
DOI : 10.1039/b807029f

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
The formation of ovarian follicles is a finely tuned process that takes place within a narrow time-window in rodents. Multiple factors and pathways have been proposed to contribute to the mechanisms triggering this process but the role of endocrine factors, especially estrogens, remains elusive. It is currently hypothesized that removal from the maternal hormonal environment permits follicle formation at birth. However, experimentally-induced maintenance of high 17β-estradiol (E2) levels leads to subtle, distinct, immediate effects on follicle formation and oocyte survival depending on the species and dose. In this study, we examined the immediate effects of neonatal E2 exposure from post-natal day (PND) 0 to PND2 on the whole organism and on ovarian follicle formation in rats. Measurements of plasma E2, estrone and their sulfate conjugates after E2 exposure showed that neonatal female rats rapidly acquire the capability to metabolize and clear excessive E2 levels. Concomitant modifications to the mRNA content of genes encoding selected E2 metabolism enzymes in the liver and the ovary in response to E2 exposure indicate that E2 may modify the neonatal maturation of these organs. In the liver, E2 treatment was associated with lower acquisition of the capability to metabolize E2. In the ovary, E2 depleted the oocyte pool in a dose dependent manner by PND3. In 10 µg/day E2-treated ovaries, apoptotic oocytes were observed in newly formed follicles in addition to areas of ovarian cord remodeling. At PND6, follicles without any visible oocyte were present and multi-oocyte follicles were not observed. Our study reveals a major species-difference. Indeed, neonatal exposure to E2 depletes the oocyte pool in the rat ovary, whereas in the mouse it is well known to increase oocyte survival.
ISSN: 1932-6203

hal-00936582
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00936582
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00936582/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00936582/file/Systemic_Compensatory_Response-accepted.pdf
DOI : 10.1371/journal.pone.0082175

Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999 15-19 octobre 1999
Résumé : Payao is a traditional concept, which has been successfully commercialized to increase the landings of several species valuable to the country's export and local industries. It has become one of the most important developments in pelagic fishing that significantly contributed to increased tuna production and expansion of purse seine and other fishing gears. The introduction of the payao in tuna fishing in 1975 triggered the rapid development of the tuna and small pelagic fishery. With limited management schemes and strategies, however, unstable tuna and tuna-like species production was experienced in the 1980s and 1990s. In this paper, the evolution and development of the payao with emphasis on the technological aspect are reviewed. The present practices and techniques of payao in various parts of the country, including its structure, ownership, distribution, and fishing operations are discussed. Monitoring results of purse seine/ringnet operations including handline using payao in Celebes Sea and Western Luzon are presented to compare fishing styles and techniques, payao designs and species caught. The fishing gears in various regions of the country for harvesting payao are enumerated and discussed. The inshore and offshore payaos in terms of sea depth, location, designs, fishing methods and catch composition are also compared. Fishing companies and fisherfolk associations involved in payao operation are presented to determine extent of utilization and involvement in the municipal and commercial sectors of the fishing industry. The issues and problems concerning the use of payao, and its biological, economic impact as well as management aspect are presented. Recommendations are given for future research and actions.

Droits : Ifremer
http://archimer.ifremer.fr/doc/00042/15284/12670.pdf
http://archimer.ifremer.fr/doc/00042/15284/

Éditeur(s) : Elsevier
Résumé : This paper examines the fishing of blackfin tuna (Thunnus atlanticus) around Fish Aggregating Devices (FADs) in Martinique (French West Indies). It is based on the compared analysis of catches from monthly experimental fishing surveys and sampling of commercial landings. The data collected in these two different ways allowed comparison of blackfin tuna length frequencies. A large part of the commercial landings were made up of young immature tuna with a fork length of less than 40 cm, whereas the experimental longline catches were mainly made up of fish with a fork length ranging between 55 and 75 cm. We give evidence that these discrepancies were mostly due to the fishing technique used. Indeed, contrarily to the experimental surveys, Martinican fishermen only fish during daytime and usually on the surface by trolling. This way, fishermen do not have access to the largest fish, which are found deeper. Out results suggested that a new fishing technique such as vertical longlining, could improve commercial catches of big blackfin tuna under FADs. (C) 2000 Ifremer/CNRS/INRA/IRD/Cemagerf/Editions scientifiques et medicales Elsevier SAS.
Aquatic Living Resources (0990-7440) (Elsevier), 2000-07 , Vol. 13 , N. 4 , P. 259-262

Droits : 2000 Ifremer/CNRS/INRA/IRD/Cemagref/Éditions scientifiques et médicales Elsevier SAS
http://archimer.ifremer.fr/doc/2000/publication-1392.pdf
DOI:10.1016/S0990-7440(00)01056-1
http://archimer.ifremer.fr/doc/00000/1392/

Éditeur(s) : HAL CCSD Society of Exploration Geophysicists
Résumé : low frequency seismic attenuation
International audience
The study of wave attenuation in partially saturated porous rocks over a broad frequency range provides valuable information about the fluid system of reservoirs, which are inherently multiple phase fluid system. Until now, not much laboratory data have been collected in the seismically relevant low frequency range and existing literature data on partially saturated rock are very limited. The main goal of our work is to experimentally measure the bulk seismic attenuation on fluid-bearing rocks, using natural rock samples in an efficient way at in situ conditions. We are currently fine-tuning our attenuation measurement prototype. Preliminary bench-top results are promising and show consistency with reported experimental data with dry, partially and fully fluid saturated rocks. Measurements with the machine are accurate and precise.
ISSN: 1052-3812

hal-00564863
https://hal.archives-ouvertes.fr/hal-00564863
DOI : 10.1190/1.3513397

Éditeur(s) : Elsevier Sci Ltd
Résumé : This study analyses the impact on the oceanic mean state of the evolution of the oceanic component (NEMO) of the climate model developed at Institut Pierre Simon Laplace (IPSL-CM), from the version IPSL-CM4, used for third phase of the Coupled Model Intercomparison Project (CMIP3), to IPSL-CM5A, used for CMIP5. Several modifications have been implemented between these two versions, in particular an interactive coupling with a biogeochemical module, a 3-band model for the penetration of the solar radiation, partial steps at the bottom of the ocean and a set of physical parameterisations to improve the representation of the impact of turbulent and tidal mixing. A set of forced and coupled experiments is used to single out the effect of each of these modifications and more generally the evolution of the oceanic component on the IPSL coupled models family. Major improvements are located in the Southern Ocean, where physical parameterisations such as partial steps and tidal mixing reinforce the barotropic transport of water mass, in particular in the Antarctic Circumpolar Current) and ensure a better representation of Antarctic bottom water masses. However, our analysis highlights that modifications, which substantially improve ocean dynamics in forced configuration, can yield or amplify biases in coupled configuration. In particular, the activation of radiative biophysical coupling between biogeochemical cycle and ocean dynamics results in a cooling of the ocean mean state. This illustrates the difficulty to improve and tune coupled climate models, given the large number of degrees of freedom and the potential compensating effects masking some biases.
Ocean Modelling (1463-5003) (Elsevier Sci Ltd), 2013-12 , Vol. 72 , P. 167-184

Droits : 2013 The Authors. Published by Elsevier Ltd. All rights reserved.
http://archimer.ifremer.fr/doc/00170/28102/26612.pdf
DOI:10.1016/j.ocemod.2013.09.001
http://archimer.ifremer.fr/doc/00170/28102/

Éditeur(s) : Pergamon-elsevier Science Ltd
Résumé : 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 carried out cross-wavelet analyses between these biological time series and a large-scale climatic index, i.e. the Southern Oscillation Index (Sol). Results showed that the biogeographic province was the most important factor structuring the patterns of variability of Japanese catch time series. Relationships between the SOI and the fish catches in the Indian and Atlantic Oceans also pointed out the role of climatic variability for structuring patterns of variation of catch time series. This work finally confirmed that Japanese longline CPUE data poorly reflect the underlying population dynamics of tunas. (C) 2010 Elsevier Ltd. All rights reserved.
Progress In Oceanography (0079-6611) (Pergamon-elsevier Science Ltd), 2010-07 , Vol. 86 , N. 1-2 , P. 276-282

Droits : 2010 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00011/12231/9029.pdf
DOI:10.1016/j.pocean.2010.04.019
http://archimer.ifremer.fr/doc/00011/12231/

Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999
Résumé : Since the beginning of 1980, the Martinique fishermen have suffered a deep crisis. The traditional ways of fishing, based on benthic fish exploitation, have seen the decreasing of their profitability due to the over-fishing of the narrow continental shelf offering few resources. The pelagic fishery had become the professional main source of income. This fishery equally encounter difficulties: denied rights of access in the EEZ of Caribbean islands, expensive costs of exploitation. The disposal of FADs offers new ways to the Martinique fishermen. In 1999, it was decided the disposal of a onetworko of 30 permanent FADs around Martinique. The mooring of these FADs must be followed by legal and economic adapted measures to reach the desired aim: the development of local fishery economy through a sustainable fishing practice. Therefore, the French authorities have decided to make the regional fishermen committee responsible for the management of FADs.This committee is the only one to be entitled to moor and to deliver licences to FADs. This committee, gathering all the fishing industry representatives, has regarding the french law the right of mooring and delivering licences to the FADs access, collecting fishery statistics. These data should fund research to improve the management of the fishery, care and replace FADs. This programas realisation, as well as durability, need adequate financial planning. It has been included in the European commission financing program. This plans success will ensure the increase of the fishermen income, maintain and develop employment.Original Abstract: Apres une periode d'experimentation lancee localement au debut des annees quatre-vingt, les premiers resultats ont ete suffisamment probants pour conduire les professionnels a souhaiter l'implantation de dispositifs de concentration de poissons (dcp) en Martinique ou a les implanter eux-memes pour la capture des dorades coryphenes, des thons noirs, de l'albacore ou du listao. Le colloque international sur la peche thoniere et les dispositifs de concentration de poissons organise du 15 au 19 octobre 1999 en Martinique donne l'occasion de revenir sur le contexte, l'interet et les modalites de developpement de la technique des dcp en Martinique.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00042/15305/12639.pdf
http://archimer.ifremer.fr/doc/00042/15305/

Éditeur(s) : HAL CCSD PubMed
Résumé : International audience
The aim of this study was to measure the heart rate (HR) response of eight elite water polo players during the four 7-min quarters of the game and to check for relationships with the physiological parameters of performance ( ·VO2max, Th1vent, Th2vent). Each athlete performed a ·VO2max treadmill test and played a water polo game wearing a heart rate monitor. The game fatigue index was calculated as the ratio of the fourth-quarter HR to the first-quarter HR: HR4/HR1. The results showed a slight decrease in fourth-quarter HR compared with the first quarter, with the mean four-quarter HR equal to 79.9 ± 4.2% of HRmax. Stepwise multiple regression analysis showed ·VO2max to be the main explanatory factor of game intensity, i.e. game HR expressed in %HRreserve (R=0.88, P<0.01). We observed that higher aerobic capacity resulted in higher game intensity. We also observed a decrease in the playing intensity in the fourth quarter compared with the first, likely due to very high game involvement. We concluded that high aerobic capacity seems necessary to ensure high game intensity in water polo. This suggests that coaches should encourage their athletes to reach a minimum level of ·VO2max and that HR monitoring could be of great interest in the control of water polo training sessions.
ISSN: 0860-021X

hal-01158208
https://hal.univ-antilles.fr/hal-01158208
DOI : 10.5604/20831862.1083277

Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999
Résumé : Rumpons, (fads) were widely deployed in Indonesia in the eighties. In the Halmahera area, rumpon increased cpue by 41% , landings of fish per ton of live bait increased by 24%, the consumption of diesel oil for tuna catches reduced by 46%, and profits increased from Rp 10 to 60 million by boat per year1. Tuna aggregation around rumpon increased catchability by more than 40% compared to free swimming tuna. The Halmahera skipjack fishery was assessed by combining catch and effort data from rumpon and pre-rumpon areas of the fishery, and showed that controlled effort could increase landings of approximately 15,000 t per year. Tagging data show that the Halmahera skipjack fishery is probably supported by a local unit stock. Philippine rumpons (payaos) were fished with small mesh purse seine and ring nets fishing small sized tunas 12-35 cm fl (40-50% of landings) and caused recruitment overfishing. Indonesian rumpons were fished with pole-and-line causing neither recruitment nor growth overfishing.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00042/15320/12658.pdf
http://archimer.ifremer.fr/doc/00042/15320/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Rapid cold hardening (RCH) is a form of thermal acclimation that allows ectotherms to fine-tune their physiological state to match rapid changes in thermal environment. Despite progress in recent years, there is still a considerable uncertainty regarding the physiological basis of RCH in insects. Here we investigated the physiological response of adult Drosophila melanogaster to a gradual reduction of temperature from 25 to 0°C followed by 1h at 0°C. As expected, this RCH treatment promoted cold tolerance, and so we hypothesized that this change could be detected at the proteomic level. Using 2D-DIGE, we found that only a few proteins significantly changed in abundance, and of these, we identified a set of four proteins of particular interest. These were identified as two different variants of glycogen phosphorylase (GlyP) of which three spots were up-regulated and another was down regulated. In subsequent experiments, we quantified upstream events by measuring the GlyP mRNA amount, but we found no marked effect of RCH. We also examined downstream events by measuring GlyP activity and the level of free sugars. We found no effect of RCH on GlyP activity. On the other hand, screening of whole animal sugar contents revealed a small increase in glucose levels following RCH while trehalose content was unaltered. This study highlights a complex regulation of GlyP in relation to RCH where we found associations between the cold tolerance, the protein abundance and the metabolite concentrations but no changes in mRNA expression and enzyme activity. These data stress the necessity of combining the hypothesis-generating power of an 'Omics' approach with subsequent targeted validations across several levels of the biological organization. We discuss reasons why different biological linked levels do not necessarily change stoichiometrically.
ISSN: 0022-1910

hal-00991032
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00991032
DOI : 10.1016/j.jinsphys.2014.01.009
PUBMED : 24508557

Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999 15-19 octobre 1999
Résumé : In Curacao, deep-water fads with grp surface buoys were developed and tested. The first fad was deployed in 1993. Up to now, a total of 5 fads were deployed at the following depths: 730, 685, 700, 754 and 574 metres. Changes were made to the surface buoy, resulting in an improved design, the mkii surface buoy. One fad lasted three years and one month. The main features of the design used are: the use of a sparbuoy design with constant tension on the moving chain to avoid slamming and jerking of the surface buoy; liberal use of sacrificial anodes, and maintenance to replace these anodes about once a year; the use of a short anchor chain with depth buoys, that does not touch bottom; a one-piece inverted mushroom anchor. With the grp surface buoy, a reserve buoyancy of approximately 800 kg is obtained with chain as external ballast about 610 kg of net buoyancy remains (it would seem that the reserve buoyancy needed where strong currents occur, has been underestimated in many designs). Five new grp mkii buoys are now under construction. Utilizing the experience gained with the deep-water fads, two new types of fads made of 500 mm diameter pvc tubes were designed to be used in waters of shallow and medium depth (150-400 m). One design uses a 3-m length of pvc tube, the other a 5-m tube (500 mm diameter). One fad with 3-m pvc buoy has been tested succesfully, two 5-m pvc buoys are under construction. The use of pvc results in a buoy which is substantially less expensive than a grp buoy. On the other hand, this type of buoy can probably not withstand the same forces as a grp buoy and we assume that for use in deeper waters the grp mkii buoy will still be needed.

Droits : Ifremer
http://archimer.ifremer.fr/doc/00042/15288/12674.pdf
http://archimer.ifremer.fr/doc/00042/15288/