Éditeur(s) : EDP Sciences
Résumé : Lessons for the future from two development projects in aquaculture in the French overseas territories. Numerous research and development projects have been launched since the seventies in the French overseas territories. Their aim was to foster new activities in agriculture based on local productions for local markets, notably in the French West Indies (FWI). In this paper we analyze two development projects on the rearing of giant freshwater prawn, one in the FWI and the other in French Guyana, over twenty years after their launching. The purpose of these compared studies is twofold: first to try to understand why a set of relevant technical innovations ended in failure 15 years later; second to identify recommendations in terms of methodology in order to diminish risks of mistakes or failure for future projects. To reach this goal we followed two approaches. A first analysis is based on a set of three criteria: social acceptability, legitimacy and time planning. The second analysis, justified by the subjective need for an explanatory tool, is based on the actor-network theory. The results show that beyond the levels of political support and financial investment and support the three key criteria for success are: (i) reactivity of the decision-makers, notably when markets change, (ii) quality of leadership transfer between the launching phase and the stabilized phase, and (iii) capacity of the decision-makers to take into account the concrete consequences of the various scenarios. Regarding this third criterion, our analysis suggests that the scenario of full technical success needs to be explored, notably in terms of economic sustainability. The integration of these two types of analyses into an ex-ante frame should contribute to reducing risks of failure in similar development projects.
De nombreux projets d’aquaculture ont été menés depuis les années 1970 dans les territoires et départements français d’outre-mer. L’objectif était de diversifier l’agriculture avec des productions destinées au marché local comme aux Antilles, ou à l’exportation comme en Guyane. L’étude s’intéresse au bilan de deux projets d’élevage de la crevette tropicale d’eau douce aux Antilles et en Guyane, plus de vingt ans après leur lancement. L’objectif est de comprendre comment des innovations technologiques pertinentes ont conduit à deux échecs sur le moyen terme et de tirer des recommandations de méthode afin de réduire les risques d’erreurs ultérieures. Pour cela, deux cadres d’analyse sont mobilisés : le premier s’appuie sur les concepts de temporalité, légitimité et acceptabilité ; le second, motivé par la recherche subjective de cadres explicatifs, emprunte la vision de la théorie de l’acteur-réseau. Les trois déterminants majeurs du succès ou de l’échec se révèlent être la réactivité des responsables face aux problèmes d’adaptation à l’évolution des marchés, la qualité du transfert du leadership lors du passage de la phase de lancement à la phase de croisière et enfin la capacité de prendre en compte dès le départ les conséquences des scénarios d’évolution du projet, y compris la réussite technique. Une capacité d’intégration de ces types d’analyse, dans un cadre ex ante, devrait permettre de réduire les risques d’échec dans des projets de développement similaires à venir.
Natures Sciences et Sociétés (1240-1307) (EDP Sciences), 2013-12 , Vol. 21 , N. 4 , P. 400-415

Droits : NSS-Dialogues, EDP Sciences 2014
http://archimer.ifremer.fr/doc/00187/29784/28242.pdf
DOI:10.1051/nss/2014004
http://archimer.ifremer.fr/doc/00187/29784/

Éditeur(s) : Edp Sciences S A
Résumé : Moored FADs (MFADs) have been a key area for development in Guadeloupe (Lesser Antilles) since the late 1980's. The main objectives underpinning the development of MFADs were to (i) reduce fishing pressure on coastal fishing resources; (ii) boost fishermen's incomes; and (iii) increase local consumption of locally generated fishery products as a proportion of overall consumption. This paper gives an overview of the current structure of Guadeloupe's fishing fleet and fisheries, with a specific focus on MFAD fleets in a relatively unstructured environment with regard to regulation, and so how these fleets operate in a context of unrestricted development of private MFADs. In addressing the following key issues, this paper aims to: assess the economic performance of fleets operating on MFADs, understand why the MFAD fishing activity has not developed more than it has, and suggest how better MFAD management could improve the situation. Socio-economic information on a trip and fleet level basis were collected and stored on a fisheries information system to analyse the relative attractiveness of MFAD fishing and assess the overall economic performance of MFAD fleets as compared to other non-MFAD fleets. Non-monetary variables were also tested to explain the degree of dependence on MFADs. In 2008, economic returns from FADs were relatively low, both in terms of wages for the crews and in terms of profit for vessel owners. Earnings were higher than coastal fishing activities, but seem to have been very sensitive to the indicators used in our analysis. MFADs are expected to become much more attractive as a result of MFAD regulation, especially through the establishment of collective MFADs.
Aquatic Living Resources (0990-7440) (Edp Sciences S A), 2013-01 , Vol. 26 , N. 1 , P. 97-105

Droits : EDP Sciences, IFREMER, IRD 2013
http://archimer.ifremer.fr/doc/00137/24836/22914.pdf
DOI:10.1051/alr/20013044
http://archimer.ifremer.fr/doc/00137/24836/

Éditeur(s) : EDP Sciences
Résumé : Batch fecundity and relative fecundity of swordfish (Xiphias gladius) in the southwestern Indian Ocean were estimated from seven gravid swordfish females (size range 127-225 cm lower jaw-to-fork length, LJFL) with unovulated, hydrated oocytes collected onboard Reunion-based (France) longline swordfish fishing vessels between December 1999 to January 2001. To investigate the spawning pattern of swordfish, we used data collected through a combination of two at sea sampling regimes. A total of 17 007 geo-located size data of swordfish were recorded during 8 years (1993-2001) and a total of 1727 (size range 75-289 cm, LJFL) swordfish gonads (1107 females and 620 males) were sampled from May 1998 to January 2001. The estimated batch fecundity ranged from 995 000 hydrated oocytes for the smallest ripe female to 4.3 millions for the largest female sampled measuring respectively 127 to 225 cm in curved length (LJFL). The relative fecundity ranged from 25 to 72 hydrated oocytes per gram of body weight. We found that batch fecundity was positively correlated with fish length and that the older/larger females have earlier and longer spawning seasons than younger/smaller females. These findings suggested that older/larger females which are seasonally migrating in this spawning ground seem to play a major role in reproductive success of the species in producing significantly more offspring than younger females during an extended spawning season. Examination of the length-frequency date from the fishery indicated that the young fish are resident around Reunion and around the seamounts off Reunion Island. Our results highlight the important role of the older/larger females in the reproductive capacity of southwestern Indian Ocean stock. We discuss the potential implications of fishing the older/larger females for this stock in terms of reproduction and recruitment.
La fécondité par acte de ponte et la fécondité relative chez l'espadon (Xiphias gladius) dans le sud-ouest de l'océan Indien sont estimées d'après sept femelles de taille comprise entre 127 et 225 cm (de l'extrémité de la mâchoire inférieure à la fourche caudale) ; celles-ci ayant atteint la maturité sexuelle, les ovaires contenant des ovocytes hydratés. Ces femelles ont été pêchées entre décembre 1999 et janvier 2001, par des palangriers ciblant l'espadon et basés à La Réunion. La stratégie de la reproduction chez l'espadon a été étudiée en utilisant des données collectées au cours de deux campagnes d'échantillonnages en mer : soit 17 007 mensurations géo-référencées d'espadons, de 75 à 289 cm, qui ont été enregistrées durant les 8 années d'étude (1993-2001) et 1727 gonades d'espadon (1107 femelles et 620 mâles) prélevées entre mai 1998 et juin 2001.La fécondité par acte de ponte estimée varie de 995 000 ovocytes hydratés, pour la plus petite femelle (127 cm), à 4,3 millions pour la plus grande femelle (225 cm). La fécondité par acte de ponte est corrélée positivement à la taille du poisson. La fécondité relative s'étend de 25 à 72 ovocytes hydratés par gramme de poids de corps. Les femelles les plus âgées/grandes pondent plus tôt et sur une période plus grande que les plus jeunes/petites femelles. Ainsi, les femelles plus âgées/grandes qui migrent de façon saisonnière vers cette aire de ponte, contribueraient plus largement au renouvellement de l'espèce en produisant de façon significative davantage de recrues que les femelles plus jeunes et ceci pendant une saison de ponte plus étendue. Par ailleurs, les jeunes individus semblent séjourner aux abords de l'île de La Réunion et des monts sous-marins situés au large. Nos résultats soulignent l'importance du rôle des femelles âgées/grandes dans la capacité reproductrice du stock d'espadon du sud-ouest de l'océan Indien. Les implications potentielles de la pêche : des femelles âgées et de grandes tailles sont discutées pour ce stock, du point de vue de la reproduction et du recrutement.
Aquatic Living Resources (0990-7440) (EDP Sciences), 2009 , Vol. 22 , N. 1 , P. 59-68

Droits : 2009 EDP Sciences
http://archimer.ifremer.fr/doc/2009/publication-6354.pdf
DOI:10.1051/alr/2009012
http://archimer.ifremer.fr/doc/00000/6354/

Éditeur(s) : HAL CCSD INRA/EDP Sciences
Résumé : 31 ref.
absent
ISSN: 0003-4312

hal-01032358
https://hal.archives-ouvertes.fr/hal-01032358

Éditeur(s) : HAL CCSD Springer Verlag/EDP Sciences
Résumé : International audience
In the dense tropical rainforest understorey, saplings exhibit different growth strategies aiming at reaching light levels better fitting their ecology. Investing mainly in height growth, at the expense of their width, a lot are close to mechanical instability. Tachigali melinonii, a long living heliophilic tree species, is frequently observed to be extremely slender and supported by neighbours. Such observations suggest an active growth control through the perception of mechanical environment. * Mechanical environment or light availability, which one is the most influent on growth and slenderness (H/D)? To test this question, we recorded growth of control and staked saplings of two species with contrasting habits and ecology: T. melinonii, and Dicorynia guianensis, along a natural light gradient. * Dicorynia, the more stable, responded more clearly to the staking treatment, showing slenderness increase when light is available, whereas for Tachigali, only light availability governed growth. * For Tachigali, growth allocation is mainly governed by light availability and ontogeny, whereas Dicorynia is probably similar to the average tree strategy, using the thigmomorphogenetic physiological process to control its stability.
ISSN: 1286-4560

hal-00534019
https://hal.archives-ouvertes.fr/hal-00534019
DOI : 10.1051/forest/2009104

Éditeur(s) : HAL CCSD EDP Sciences
https://hal.archives-ouvertes.fr/hal-00521898

hal-00521898
https://hal.archives-ouvertes.fr/hal-00521898

Éditeur(s) : EDP Sciences
Résumé : We present results obtained from a pristine site of French Guiana (South America), at the Pic Matecho, a region far from gold mining activity. This area contains a small permanent lake, a rare situation in French Guiana. Tree canopy, soils and Lake Matecho sediments were analysed in total Hg and Pb-210. The annual deposit of litterfall is estimated at 40 mug (Hg)/m(2)/y. The top sediment content of 0.2 mug (Hg)/g indicates a large contribution of the atmospheric deposit. In sediment, the decrease of total Hg with depth is neither due to local human influence, nor to increase of atmospheric background during this century. It is attributed to remineralization of organic matter in the upper part of the sediment : the majority of the total Hg deposited at the water/sediment interface is not permanently trapped in the sediment but remobilized in water. Interpretation of the historical sediment profile suggests a constant deposit rate over the last millennium.
Journal De Physique Iv (1155-4339) (EDP Sciences), 2003-05 , Vol. 107 , P. 859-862

Droits : 2003 EDP Sciences
http://archimer.ifremer.fr/doc/00000/10630/9348.pdf
DOI:10.1051/jp4:20030433
http://archimer.ifremer.fr/doc/00000/10630/

Éditeur(s) : EDP Sciences
Résumé : Market position and its evolution were analysed in nine key fish and cephalopod species subject to long-term changes, using the Bay of Biscay fisheries as a case study. Although such long term changes have already been documented, and in some cases shown to be related to the impacts of fishing, changes in the physical environment, or both, relatively little work has been devoted to their potential consequences in economic terms. The nature and extent of these consequences was determined in the present study by looking at the composition of the affected fish production, and the status of different fish products on the markets. We propose a methodology to characterize market position for this set of nine species. The selected species represent a significant part of the gross turnover of French fishing fleets operating in the bay. These species were characterized in terms of their potential sensitivity to fishing and changes in environmental conditions due to global warming. We separated species potentially positively (Engraulis encrasicolus and Lophius budegassa) and negatively affected (Pollachius pollachius and Lophius piscatorius) by warming. Evolution of the value of production of the nine species was then depicted using analysis of macro-economic index (production and potential consumption) and price indices. This revealed the relatively high sensitivity of domestic production to the market crisis that occurred in France in the early 1990s, compared to imported and exported products. The relative position of individual species, with respect to the market and its evolution between 1990 and 2005, was analyzed by multi-factorial analysis. Results derived from the analysis clearly distinguish two groups of species, the first characterized by higher prices (monkfish, Nephrops, sole, seabass) and the second by larger volumes available on the French market (pollack, hake, anchovy, sardine, cuttlefish). We conclude that a major part (69 to 87%) of the gross turnover associated with catches of these fish species in the Bay of Biscay remains potentially unaffected by long-term changes related to climate.
Aquatic Living Resources (0990-7440) (EDP Sciences), 2008-07 , Vol. 21 , N. 3 , P. 307-316

Droits : EDP Sciences, IFREMER, IRD 2008
http://archimer.ifremer.fr/doc/2008/publication-4716.pdf
DOI:10.1051/alr:2008047
http://archimer.ifremer.fr/doc/00000/4716/

Éditeur(s) : HAL CCSD INRA/EDP Sciences
Résumé : 41 ref.
absent
ISSN: 0003-4312

hal-01032361
https://hal.archives-ouvertes.fr/hal-01032361

Éditeur(s) : Edp Sciences S A
Résumé : This study was designed to measure responses of four-year-old black-lip pearl oysters (Pinctada margaritifera) to different temperatures and food concentrations and to identify the energy requirements of each sex. Oysters were fed a monospecific microalgal diet of Isochrysis affinis galbana (T-iso). Measurements of oxygen consumption and ingestion rates were carried out at 24 degrees C and 27 degrees C and at two algal (T-iso) concentrations: 5000 and 30 000 cell ml(-1). Glycogen content in adductor muscle, absorption efficiency and scope for growth were also estimated. Females and males responded differently to environmental factors, with food level being the most influential parameter. Oxygen consumption and absorption efficiency were significantly higher in females than in males, but males had significantly higher glycogen content than females. At high food concentration, glycogen content, ingestion rate, oxygen consumption, and scope for growth were significantly higher than at the low food concentration. Only absorption efficiency was significantly higher at the low food concentration. Oxygen consumption was significantly higher at 27 degrees C than at 24 degrees C. These results indicate that females and males have different bioenergetic functioning and that energy demands for reproduction are higher in females.
Aquatic Living Resources (0990-7440) (Edp Sciences S A), 2013-07 , Vol. 26 , N. 3 , P. 263-271

Droits : EDP Sciences, IFREMER, IRD 2013
http://archimer.ifremer.fr/doc/00157/26855/24980.pdf
DOI:10.1051/alr/2013059
http://archimer.ifremer.fr/doc/00157/26855/

Éditeur(s) : HAL CCSD Springer Verlag/EDP Sciences
Résumé : International audience
Context : Functional - structural models (FSM) of tree growth have great potential in forestry, but their development, calibration and validation are hampered by the difficulty of collecting experimental data at organ scale for adult trees. Due to their simple architecture and morphological properties, " model plants " such as Cecropia sciadophylla are of great interest to validate new models and methodologies, since exhaustive descriptions of their plant structure and mass partitioning can be gathered. * Aims : Our objective was to develop a model-based approach to analysing the influence of environmental conditions on the dynamics of trophic competition within C. sciadophylla trees. * Methods : We defined an integrated environmental factor that includes meteorological medium-frequency variations and a relative index representing the local site conditions for each plant. This index is estimated based on model inversion of the GreenLab FSM using data from 11 trees for model calibration and 7 trees for model evaluation. * Results : The resulting model explained the dynamics of biomass allocation to different organs during the plant growth, according to the environmental pressure they experienced. * Perspectives : By linking the integrated environmental factor to a competition index, an extension of the model to the population level could be considered.
ISSN: 1286-4560

hal-00780347
https://hal-ecp.archives-ouvertes.fr/hal-00780347
https://hal-ecp.archives-ouvertes.fr/hal-00780347/document
https://hal-ecp.archives-ouvertes.fr/hal-00780347/file/Letort2011AFS.pdf
DOI : 10.1007/s13595-011-0131-x

Éditeur(s) : HAL CCSD Springer Verlag/EDP Sciences
Résumé :  
absent
ISSN: 1286-4560

hal-01032143
https://hal.archives-ouvertes.fr/hal-01032143
DOI : 10.1051/forest:2008061

Éditeur(s) : HAL CCSD Springer Verlag/EDP Sciences
Résumé : International audience
We present a plant trait database covering autecology for rain forest trees of French Guiana. The database comprises more than thirty traits including autecology (e.g., habitat associations and reproductive phenology), wood structure (e.g., density and tension characteristics) and physiology at the whole plant (e.g., carbon and nitrogen isotopes) and leaf level (e.g., specific leaf area, photosynthetic capacity). The current database describes traits for about nine hundred species from three hundred genera in one hundred families. For more than sixty species, data on twelve morphological and ecophysiological traits are provided for individual plants under different environmental conditions and at different ontogenetic stages. The database is thus unique in permitting intraspecific analyses, such as the effects of ontogenetic stages or environmental conditions on trait values and their relationships.
ISSN: 1286-4560

Droits : info:eu-repo/semantics/OpenAccess
hal-00884130
https://hal.archives-ouvertes.fr/hal-00884130
https://hal.archives-ouvertes.fr/hal-00884130/document
https://hal.archives-ouvertes.fr/hal-00884130/file/hal-00884130.pdf

Éditeur(s) : Edp Sciences S A
Résumé : Reared sea bass were submitted to six stressful situations: hyperoxia with or without hypercapnia, increased stocking density in an open flow or recirculating system, transfer to another tank and nodavirus injection. The potentially negative impact of these factors on the lives of sea bass was investigated by measuring 9 water parameters and 19 fish parameters including total serum protein (TSP). TSP has already been used to evaluate stress. The present study investigates data of previous and new experiments, concentrating on the potential use of TSP as a routine indicator to assess welfare in sea bass reared on fish farms. In the current experiment, oxygen and carbon dioxide were seen to affect levels of TSP, but alterations were too erratic to enable proper comparison, probably because they are normal components of the fish environment and become toxic only by dose increase. TSP decreased when stocking density increased. After transfer to another tank, TSP decreased to 14% for three weeks and then increased during the fourth week through compensative overproduction, before returning to normal levels after 2 months. The results confirmed that transfer is an important stress factor for fish, with cumulative effects for successive transfers. TSP alteration of nodavirus-injected fish depends on the type of symptoms, which can be divided into 3 groups: (i) dying fish, in which TSP increased sharply due to over-production of protein involved in non-specific defences and inflammation, then decreased dramatically before death; (ii) whirling fish, a group that included both fish that later died, in which TSP decreased, and fish that subsequently survived, in which TSP increased due to development of specific immunity; and (iii) asymptomatic fish, in which TPS was similar to control levels and which were probably insensitive to nodavirus and/or had developed defences. In this paper, different mechanisms of TSP alteration are proposed and the interest of TSP as a field parameter is discussed. TSP is a non-destructive parameter that is robust, easy to measure everywhere and cheap, representing a suitable way of monitoring the overall welfare of fish by its regular increase. It can be used only as a "warning" of poor rearing conditions, however, and further investigations would be needed to identify the specific stress or health disorder.
Aquatic Living Resources (0990-7440) (Edp Sciences S A), 2011-04 , Vol. 24 , N. 2 , P. 121-127

Droits : EDP Sciences, IFREMER, IRD 2011
http://archimer.ifremer.fr/doc/00043/15382/12740.pdf
DOI:10.1051/alr/2011130
http://archimer.ifremer.fr/doc/00043/15382/

Éditeur(s) : HAL CCSD Springer Verlag/EDP Sciences
Résumé : International audience
Context: Woodcutting is a very old technology but scientific research is scarce on the subject. In the last 50 years much work on basic mechanisms as well as industrial processes has been done in France. Aims: The specific nature of wood introduces strong differences between wood and metal cutting processes. The paper focuses on French teams' contributions. Results: The basic aspects of the tool–material interaction for different basic modes in woodcutting are highlighted. In primary conversion such as sawing, veneer cutting or green wood chipping, huge progress comes from automation and the possibility of linking the process to log and product quality through new sensors. In secondary processing much has been done on the links between the cutting process, surface qualification and the properties of these surfaces for further processing, such as gluing or coating. Tool wear depends on the cutting process, timber quality, and species. Trade-offs are required in tool technology and coating technologies may improve tool life. Conclusion: A large amount of knowledge and innovation has come from 50 years of worldwide research effort, with France being particularly active in this period. The transfer of skills from metals cutting industry was often a key, but much is needed to move closer to both metal cutting sector and woodcutting skills among craftsmen.
ISSN: 1286-4560

hal-01135156
https://hal.archives-ouvertes.fr/hal-01135156
https://hal.archives-ouvertes.fr/hal-01135156/document
https://hal.archives-ouvertes.fr/hal-01135156/file/Wood_machining_focus_French_research_Thibaut_al_2015.pdf
DOI : 10.1007/s13595-015-0460-2

Éditeur(s) : HAL CCSD EDP Sciences
Résumé : International audience
Au siècle dernier, plus exactement en avril 1995, la revue médecine/sciences consacrait pour la première fois un de ses numéros au testicule. Dix sept ans plus tard, le saut du siècle accompli, il est frappant de constater que la publication de ce premier numéro suivait de peu la survenue de trois événements qui allaient totalement bouleverser non seulement le champ de la médecine et des sciences relatif à la fertilité humaine, mais aussi le rapport des humains aux mystères de leur conception, de la détermination du sexe, et à leur environnement...
ISSN: 0767-0974

hal-00877251
https://hal.archives-ouvertes.fr/hal-00877251
https://hal.archives-ouvertes.fr/hal-00877251/document
https://hal.archives-ouvertes.fr/hal-00877251/file/La_infertilitA_mA_le_aujourda_hui-accepted.pdf
DOI : 10.1051/medsci/2012285001

Éditeur(s) : HAL CCSD EDP Sciences
Résumé : International audience
This paper presents a paleo-hydrological study conducted on sediment flood deposits at two sites located in the Gardon Gorges, Southeast France. The first study site is a valley‑side terrace (referred to as site GE, located 10m above the channel bed) and the second is located in a cave (referred to as site GG, perched 15m above the bed level). Paleo‑flood events were identified by carefully analyzing each slackwater flood deposits. The flood units were then dated using a variety of dating techniques, namely 137Cs, 210Pbex, 14C geochemical analysis of mining‑contaminated slackwater flood sediments, archeological objects and the historic flood record. Hydraulic modeling was also carried out in order to verify the coherence between the stratigraphic records of flood deposits at the sites and the historic flood levels known along the river Gardon. It is demonstrated that all the major flood events of the 20th century can be identified at terrace GE. This type of geomorphological unit can therefore be used as a sound basis for a paleo-hydrological analysis of the Gardon Gorges. Furthermore, the analysis of the stratigraphic record at site GG demonstrates that the site can be used to trace the largest flood events that have occurred within the past 600 years. The study reveals that the frequency of extreme flood events increased during the Little Ice Age
Une étude paléo-hydrologique a été entreprise dans les Gorges du Gardon, où deux coupes sédimentaires ont été étudiées. La première provient d'une terrasse (coupe GE située à 10 m de hauteur au dessus de la rivière) et l'autre, d'une cavité (coupe GG localisée à 15 m au-dessus de la rivière). L'identification et la mise en évidence des différents paléo-événements de crue ont été établies grâce à l'inspection minutieuse de chaque dépôt sédimentaire et d'une étude géochronologique fine (137Cs, 210Pbex, 14C, métaux traces, objets archéologiques, historiques des crues). Nous avons souhaité évaluer la capacité des terrasses fluviatiles du Gardon à enregistrer des paléo-événements en comparant les coupes sédimentaires aux données historiques des hauteurs d'eau et aux résultats d'un modèle hydraulique 1D. Nous montrons que la terrasse GE enregistre la quasi-totalité des évènements du 20ème siècle et qu'à priori, ce type d'objet géomorphologique peut être utilisé pour toute étude paléo-hydrologique sur le Gardon. De plus, l'étude de la coupe GG (cavité perchée à 15 m) permet de reconstituer les évènements intenses au cours des 600 dernières années. Nous montrons une augmentation des crues extrêmes dans le Haut-Languedoc au cours du "Petit âge glaciaire".
ISSN: 0018-6368

hal-01108400
https://hal.archives-ouvertes.fr/hal-01108400
https://hal.archives-ouvertes.fr/hal-01108400/document
https://hal.archives-ouvertes.fr/hal-01108400/file/ly2014-pub00041935.pdf
DOI : 10.1051/lhb/2014037

Éditeur(s) : EDP Sciences
Résumé : Selective fishing pressure on more highly valued marine living resources is one of the key factors proposed to explain changes occurring in fish communities and associated landings of commercial fisheries. The aim of this paper is to establish the nature of changes in the landings of French fishing fleets operating in the Bay of Biscay in the period 1973-2002, and whether these changes could be related to the relative economic attractiveness of different fish species. The analysis focuses on trends observed in the landings of all commercial fish species over the last three decades. It is based on data of annual quantities landed and ex-vessel prices compiled from official French landings records, and on bio-geographical descriptors of these species derived from published data. Using simple index numbers and multivariate analysis, we examined changes in total landings in terms of their volume and value, as well as changes in their composition. We show that the composition of landings significantly changed over the study period, with an increase in the proportion of pelagic species, of lower economic value. The average ex-vessel price of production by the fleets tended to decrease from the late 1980s; partly due to a cross-species drop in prices, occurring mainly after 1993, but also to the increased proportion of low-priced species in the landings. This caused a significant drop in the total gross value of production in the second half of the study period.
La pression de pêche sélective sur les ressources marines vivantes de forte valeur est un des facteurs-clés proposés pour expliquer les changements qui surviennent dans la structure des communautés de poisson et dans les débarquements des pêcheries commerciales associés. L'objectif de cet article est d'établir la nature des changements dans les débarquements des flottilles de pêche françaises opérant dans le golfe de Gascogne, et d'examiner les relations entre ces changements et l'attractivité relative des espèces de poisson d'un point de vue économique. L'analyse se concentre sur les tendances observées au cours des trois dernières décennies dans les débarquements de toutes les espèces commerciales de poissons effectués par les flottilles de pêche opérant dans le golfe. Elle s'appuie sur des données concernant les quantités annuelles débarquées, les prix compilés à partir des enregistrements officiels des débarquements français, et les données publiées concernant les caractéristiques biogéographiques des espèces étudiées. En s'appuyant sur des indices simples et une analyse multivariée, on examine les changements des débarquements totaux en volume et en valeur, ainsi que les changements dans leur composition. On montre que la composition des débarquements a fortement changé au cours de la période étudiée, avec un accroissement important de la part des espèces pélagiques, de plus faible valeur. Le prix moyen de la production a eu tendance à décroître depuis la fin des années 1980. Ceci est en partie dû à une chute des prix de l'ensemble des espèces, après 1993, et en partie lié à l'accroissement de la part des espèces de plus faible valeur dans les débarquements. Une baisse importante de la valeur de la production en a découlé sur cette deuxième moitié de la période d'étude.
Aquatic Living Resources (0990-7440) (EDP Sciences), 2008-07 , Vol. 21 , N. 3 , P. 317-327

Droits : 2008 EDP Sciences
http://archimer.ifremer.fr/doc/2008/publication-5926.pdf
DOI:10.1051/alr:2008048
http://archimer.ifremer.fr/doc/00000/5926/

Éditeur(s) : HAL CCSD ESAIM Proceedings, EDP Sciences
https://hal.archives-ouvertes.fr/hal-01066579

hal-01066579
https://hal.archives-ouvertes.fr/hal-01066579

Éditeur(s) : HAL CCSD INRA/EDP Sciences
Résumé : 3 ref.
Des relevés de terrain ont été effectués afin d'étudier la phénologie d'une espèce des forêts de basse altitude des Antilles : le Tabebuia heterophylla. Parallèlement un stockage à basse température a pu étendre à huit mois la longévité des graines. Une technique simple de bouturage est mise au point.
ISSN: 0003-4312

hal-01032289
https://hal.archives-ouvertes.fr/hal-01032289