Spatial, Ecological and Social Dimensions of Assessments for Bivalve Farming Management

The general purpose of assessment is to provide decision-makers with the best valuable data, information, and predictions with which management decisions will be supported. Using case studies taken from four scientific projects and dealing with the management of marine bivalve resources, lessons learned allowed identifying some issues regarding assessment approaches. The selected projects also introduced methodological or institutional frameworks: ecosystem approach to aquaculture (EAA), system approach framework (SAF), marine spatial planning (MSP), and valuation of ecosystem services (ES). The study on ecosystem services linked ES to marine habitats and identified ES availability and vulnerability to pressures. The results were displayed as maps of resulting potential services with qualitative metrics. The vulnerability value is an alternative to monetary valuation and, in addition to identifying the most suitable areas for each type of ES, this metric allows identifying the management strategies that will most probably maintain or affect each individual ES. The MSP example focused on bivalve farming activity and accounted for several criteria: habitat suitability, growth performance, environmental and regulation constraints and presence of other activities. The ultimate endpoint of such an approach is a map with qualitative values stating whether a location is suitable or not, depending on the weight given to each criterion. In the EAA case study, the indicator was defined by the growth performance of cultivated bivalves in different locations. This indicator is affected by distant factors – e.g. populations of marine organisms competing for the same food resource, nutrient inputs from rivers, time to renew water bodies under the action of tidal currents. The role and interactions of these factors were assessed with a dynamical ecosystem model. Examples illustrate that the assessment is often multi-dimensional, and that multiple variables would interact and affect the response to management options. Therefore, the existence of trade-offs, the definition of the appropriate spatial scale and resolution, the temporal dynamics and the distant effects of factors are keys to a policy-relevant assessment. EA and SAF examples show the interest of developing models relating response to input variables and testing scenarios. Dynamic models would be preferred when the relationship between input and output variables may be masked by non-linear effects, delay of responses or differences of scales. When decision-making requires economic methods, monetary values are often of poor significance, especially for those ecosystem services whose loss could mean the end of life, and appear to be a comfortable oversimplification of reality of socio-ecological systems which cannot be summarized in single numbers. Alternative methods, such as the ones proposed in the SAF and ES examples, would preferably consider institutional analysis or multicriteria assessment rather than single monetary values. Case studies also highlighted that credibility of assessment tools benefit from the association of stakeholders at different stages, among which: identification of the most critical policy issues; definition of system characteristics including ecological, economical and regulation dimensions; definition of modelling scenarios to sort out the most effective management options; assessment of models and indicators outputs.publishedVersio

Impact of Cultural Practices on the individual and Collective Economic Performances in Shellfish Farming: the Case of Oyster Farming in Baie Des Veys

The access regulation within the shellfish farming sector in France is based on a co-management system relying on both a national legislation, defining the general access conditions to maritime public grounds, and regional regulation systems, called “Regional Structural Schemes”. The latter specify the farming rules in cooperation with the administration, scientific and professional representatives. This regulation system, which aims at managing the common primary resources at the scale of a shellfish farming basin, is under review in the baie des Veys, on the Normandy coastline. In this context, biological modelling is used to assess the carrying capacity of the bay and to provide tools for modifying the RSS in a more sustainable way. Another objective of the study is to shift to bio-economic modelling, implying for the model to take into account extra technical and economical parameters. A specific survey has therefore been carried out for collecting detailed information on the cultural practices of the oyster farming companies, and for analysing the links with their structural characteristics and performance indicators, in terms of productivity and output. This article reviews the context of oyster farming in the baie des Veys from the environmental, socio-economic and institutional point of view. After the presentation of the methodology used for the survey, its results are analysed and a synthesis is made, leading to the identification of the main farming technical profiles. At this stage of the study, only theoretical developments on modelling are considered and outlooks in terms of collective management measures are discussed.Keywords: Aquaculture, Fisheries Economics, Aquaculture Efficiency and Managemen

Εισοδηματικές ανισότητες και φιλανθρωπία

<p>All variables were kriged on different variogram models depending on the data (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0044155#pone-0044155-t001" target="_blank">Table 1</a>). Geometrical scales were used to maximize the visualization of both gradients and the patchiness of the different variables. Mollusk maps are at different scales to account for the discrepancy in the data between the 2 samplings. <b>A, B</b>: Chl <i>a</i> concentration (µg.L⁻¹); <b>C, D</b>: SPiM amount (mg.L⁻¹). <b>E, F</b>: Bottom mean current velocities and direction at the 2 sampling periods, calculated by the MARS-3D hydrodynamic model.</p

Projet OGIVE. Outils d’aide à la Gestion Intégrée et à la Valorisation des Ecosystèmes conchylicoles de Basse-Normandie. Rapport final d’activités - Phase I (2005-2008)

L’objectif général du projet OGIVE est d’acquérir des connaissances sur le fonctionnement des écosystèmes conchylicoles de Basse-Normandie dans le but d’établir une plateforme de données communes à l’ensemble des partenaires du projet. Ces connaissances sont ensuite utilisées pour développer des outils novateurs permettant de fournir des avis et expertises aux gestionnaires du Domaine Public Maritime. Le projet a ainsi pour objectif de contribuer au développement durable de la filière conchylicole en Basse-Normandie en optimisant la production conchylicole et en préservant la qualité environnementale des écosystèmes qui supportent cette activité. Le projet OGIVE a été structuré initialement autour du développement de trois outils : 1) Un outil empirique sous Système d’Information Géographique destiné à répondre aux questions de gestion relatives aux restructurations à l’échelle d’une concession, 2) Un outil de modélisation non spatialisé (i.e. modèle d’écosystème biologique) permettant d’estimer la capacité de support trophique (i.e. biomasse maximale à mettre en exploitation compte tenu de la nourriture disponible dans l’écosystème) de chacun des sites de production bas-normands, 3) Un outil de modélisation spatialisé (i.e. modèle d’écosystème couplant les processus physiques & biologiques) permettant d’affiner les estimations de capacité de support trophique et de tester différents scénarios de réaménagement des zones d’élevage. Le présent rapport est dédié à la présentation des résultats acquis au cours de la première phase du projet (2005-2008)

Etude in situ et expérimentale de l'effort de reproduction chez l'huître perlière Pinctada margaritifera

The aim of this work is to study reproductive effort of the pearl oyster Pinctada margaritifera. In order to reach this objective, two experiences were planned. First, we decidcd to follow in situ growth and reproduction of pearl oysters of three age groups : l, 2 and 3 years old. This projcct began at the end of march 1997 and is planned for one year. The results presented in this study stopped at the end of july 1997. This experience is based on the bimonthly sampling of 120 pearl oysters (40 from every age group) from the lagoon of Takapoto (Tuamotu, French Polynesia). ln a second part, an experience was lead in laboratory, on the same animals. The objective was to trigger artificially spawns and to harvest genital products to estimate values of reproductive effort. The in situ experience has shown an important and synchronous spawn at the end of may, for pearl oysters aged of 2 and 3 years. This observation allowed to estimate a reproductive effort, on the period, for these two age groups : 310 mg for the two years old and 390 mg for the three years old. Any important spawn was observcd, on the period, in one year old, although the sexual maturity is already got because of genital products presence. More generally, the reproductive cycle of Pinctada margaritifera is characterized by many partial and asynchronous spawns, ali along the year. Regressions microscopically observed, in this study, show partial and asynchronous spawns or cellular resorptions without spawn. The laboratory experience allowed to estimate a reproductive effort of the three age groups : 29 mg for the one year old, 105 mg for the two years old and 117 mg for the three years old. The results are underestimated in relation to results obtained by the in situ experience, except for one year old. However, it showed that the one year old have a small reproductive effort in relation to the two other age groups. Moreover, two years old presente a  less important reproductive effort than the three years old. Finally, this experience, which was lead about two temperatures (26 and 31 °C), showed no influence of this factor on gametogenesis of the species.L'objectif de ce travail est l'estimation de l'effort de reproduction de l'huître perlière Pinctada margaritifera. Pour ce faire, deux expérimentations ont été mises en oeuvre : - Une étude in situ a permis de suivre la croissance et la reproduction d'huîtres perlières, âgées de l, 2 et 3 ans, élevées dans le lagon de Takapoto, sur la période du 25 mars au 29 juillet 1997. Ce suivi est basé sur le prélèvement bimensuel de 120 huîtres perlières (40 par classes d'âge). - Une étude expérimentale, visant à compléter le suivi in situ, a été menée sur les mêmes animaux. L'objectif était d'obtenir artificiellement des pontes, d'en récolter les produits et de mesurer les valeurs d'effort de reproduction par deux méthodes, en poids et en nombre. L'expérience in situ a montré, pour les huîtres de 2 et 3 ans, l'existence d'une ponte synchrone et importante à la fin du mois de mai. Cette observation a permis d'estimer la production de gamètes (Pr) ainsi que l'effort de reproduction (ER) sur la période pour ces deux classes d'âge : environ 310 mg pour les huîtres âgées de deux ans et environ 390 mg pour les huîtres âgées de 3 ans. Sur cette période, aucune ponte importante n'a été mise en évidence chez les huîtres âgées d' 1 an, bien que la maturité sexuelle soit déjà acquise à cet âge, puisque ces animaux possèdent des produits génitaux. Plus généralement, le cycle de reproduction de Pinctada margaritifera se caractérise par des pontes partielles asynchrones tout au long de la période et pour les trois classes d'âge. Ceci est montré par la présence quasi-permanente de régressions observées microscopiquement. Ces régressions sont, soit le témoin de pontes partielles et asynchrones non quanti fiables, soit le témoin d'une résorption lors de périodes d'amaigrissement. L' étude expérimentale a permis d'estimer une production de gamètes pour les trois classes d'âge d'environ 29 mg pour les 1 an, 105 mg pour les 2 ans et 117 mg pour les 3 ans. Les résultats expérimentaux sont plus faibles que ceux obtenus lors du suivi in situ mais les tendances sont similaires. Les huîtres d' 1 an s' investissent moins dans leur fonction de reproduction que les nacres de 2 et 3 ans. L'investissement des huîtres perlières dans leur fonction de reproduction augmente avec l'âge. Enfin, cette expérience, menée sur deux températures (26 et 31 °C), a également montré l'absence d ' influence de cc facteur sur la maturation