Elements for a Theory of Financial Risks

Estimating and controlling large risks has become one of the main concern of financial institutions. This requires the development of adequate statistical models and theoretical tools (which go beyond the traditionnal theories based on Gaussian statistics), and their practical implementation. Here we describe three interrelated aspects of this program: we first give a brief survey of the peculiar statistical properties of the empirical price fluctuations. We then review how an option pricing theory consistent with these statistical features can be constructed, and compared with real market prices for options. We finally argue that a true `microscopic' theory of price fluctuations (rather than a statistical model) would be most valuable for risk assessment. A simple Langevin-like equation is proposed, as a possible step in this direction.Comment: 22 pages, to appear in `Order, Chance and Risk', Les Houches (March 1998), to be published by Springer/EDP Science

Climate determines transmission hotspots of Polycystic Echinococcosis, a life-threatening zoonotic disease, across Pan-Amazonia

Polycystic Echinococcosis (PE), a neglected life-threatening zoonotic disease caused by the cestode is endemic in the Amazon. Despite being treatable, PE reaches a case fatality rate of around 29% due to late or missed diagnosis. PE is sustained in Pan-Amazonia by a complex sylvatic cycle. The hunting of its infected intermediate hosts (especially the lowland paca ) enables the disease to further transmit to humans, when their viscera are improperly handled. In this study, we compiled a unique dataset of host occurrences (~86000 records) and disease infections (~400 cases) covering the entire Pan-Amazonia and employed different modeling and statistical tools to unveil the spatial distribution of PE's key animal hosts. Subsequently, we derived a set of ecological, environmental, climatic, and hunting covariates that potentially act as transmission risk factors and used them as predictors of two independent Maximum Entropy models, one for animal infections and one for human infections. Our findings indicate that temperature stability promotes the sylvatic circulation of the disease. Additionally, we show how El Niño-Southern Oscillation (ENSO) extreme events disrupt hunting patterns throughout Pan-Amazonia, ultimately affecting the probability of spillover. In a scenario where climate extremes are projected to intensify, climate change at regional level appears to be indirectly driving the spillover of . These results hold substantial implications for a wide range of zoonoses acquired at the wildlife-human interface for which transmission is related to the manipulation and consumption of wild meat, underscoring the pressing need for enhanced awareness and intervention strategies

La pêche chez les Wayana, Teko et Aluku en 2014 sur le Haut-Maroni (Guyane française) : complémentarité des enquêtes halieutiques et des cartes cognitives

Fishing encompasses major heritage, economic, cultural and ecological challenges on the Upper Maroni Basin (French Guiana). This study aims at characterizing the Aluku, Wayana and Teko fisheries through two complementary approaches :1. Multiscale (fisher villages, communities, Upper Maroni River) fish landings surveys for 4 seasons (2013-2014) led to assess the fishing effort, average yields, diversity and number of species landed and the available fish biomass per capita.2. Semi-structured interviews and the development of 45 cognitive maps have allowed :- to supplement the quantitative survey data together with the empirical knowledge and perceptions of Aluku and Amerindians fishers.- to assess qualitatively and semi-quantitatively the anthropo-ecosystem changes in these fisheries between 1960 and 2014, and cultural representations for local people.In a context of increasing and sedentary populations, fisheries is now based on daily fishing trips within shrinking village territories and some distant expeditions. A significant decline in fish production and part of fish in the inhabitants‘ diet has been raised since the 1960s. This decrease was due in part to a slowdown in demand, based on cultural opportunities to cope with changes linked to globalization lifestyles. Moreover, fisheries activity is strongly affected by clandestine gold washing. The fish stocks in this river look more jeopardized in two living areas (Twenké and Loca) compared to other sectors. Facing these changes, it seems relevant to use these initial findings to contribute to co-build the future of this river and its inhabitants.Sur le bassin du Haut-Maroni (Guyane française), la pêche recouvre des enjeux patrimoniaux, économiques, culturels et écologiques majeurs depuis toujours. L’objectif de cette étude était de caractériser les pêcheries de petite échelle Aluku, Wayana et Teko par deux approches complémentaires :1. Les enquêtes de débarquements sur quatre périodes saisonnières de 15 jours représentatives (2013-2014) ont permis d'évaluer à différentes échelles (villages de pêcheurs, communautés, Haut Maroni) l'effort de pêche, les rendements moyens, la diversité et le nombre d'espèces débarquées ainsi que la biomasse de poisson pêchée disponible par habitant.2. Des entretiens semi-directifs et l'élaboration avec 45 pêcheurs de cartes cognitives associées à une ontologie, ont permis :- de compléter les données quantitatives, par la mémoire, les perceptions et le savoir empirique.- évaluer qualitativement et semi-quantitativement, les changements de l’anthropo-écosystème des pêcheries entre les années 1960 et 2014, et ce qu’il représente pour les populations locales.Dans un contexte de croissance et de sédentarisation des populations, la pêche repose aujourd’hui sur des sorties à la journée dans des zones d’exploitation villageoises restreintes et des expéditions plus lointaines sur quelques jours. Depuis les années 1960, on observe une diminution significative de la production halieutique et de la part du poisson dans l'alimentation des habitants. Cette baisse est due en partie à un ralentissement de la demande, fondé sur des particularités culturelles permettant de s’adapter aux changements de modes de vie liés à la globalisation. De plus, l’activité halieutique est fortement impactée par l’orpaillage clandestin. Les stocks halieutiques de deux zones d’exploitation (Twenké et Loca) semblent plus fragilisés que dans les autres secteurs de l’étude. Face à ces changements autour de la pêche, il semble pertinent de prendre en compte ces résultats pour participer avec les habitants, à la co-construction de l'avenir socio-économique de ce bassin fluvial

Aspects juridiques et déontotlogiques des bars à sourire

AIX-MARSEILLE2-BU Méd/Odontol. (130552103) / SudocSudocFranceF

Hunting in French Guiana Across Time, Space and Livelihoods

Hunting sustainability in Amazonian ecosystems is a key challenge for modern stakeholders. Predictive models have evolved from first mostly biological data-based to more recent modeling including human behavior. We analyze here the hunting data collected in French Guiana through a panel of indices aiming at drawing the puzzle of parameters influencing hunting activity and impact in various socio ecological conditions across the country. Data were collected from five different study sites differing in cultural origins and remoteness from market economy, and over a 10 years period. Most indices show an impact on wildlife populations, and using a full set of indicators allowed us to better understand some underlying mechanisms that lead to a community's hunting profile. The results showed that there are noticeable differences between the study sites in the practices and the ways hunters face the changes in environment and resources availability

La participation des communautés amérindiennes et bushinenguées à la gestion durable, concertée et appropriée des pratiques liées aux ressources naturelles dans un parc national. Un projet innovant en France

International audienc

Perception par les pêcheurs de leurs ressources fluviales : étude du cas des populations autochtones de Guyane à l’aide de la cartographie cognitive contextuelle

International audienceThis study focuses on fishers’ perceptions of interactions between their practices and their environment. The study was performed in the upper section of the Maroni River in French Guiana, a relatively remote region in the tropical rainforest where subsistence fishing still occurs. We assessed the fishers’ perceptions of their relationship with the river by asking them about the state of natural resources, their fishing practices, nearby activities, and their way of life. Cognitive mapping was used to capture their individual viewpoints, especially those that formed a consensus with the other fishers. Regardless of their ethnic group (Aluku vs. Amerindian) or way of life (subsistence vs. commercial fishing), most fishers generally shared the same views. The main perception was that fishing is threatened by illegal gold mining, increasing use of fishing nets, and a loss of knowledge of fish behaviour by younger generations of villagers. Furthermore, fishers perceived an ongoing shift in their role and relationship with the fish resource, which is becoming increasingly commercially oriented, and since the river is no longer the only source of food. Detailed analysis of arguments put forward to explain these threats shows that this process originates from ill-managed Westernization, which has caused painful changes in lifestyles of local populations, especially Amerindians. This analysis can also provide local governments with mechanisms for action. Our results raise questions about the future of this region and suggest ways to protect its natural resources better. They can help decision makers respond to poorly understood informal fisheries and motivate local residents to contribute to sustainable management of a river’s natural resources.Dans un contexte de forte transition socio-économique au sein des populations Amérindiennes et Bushinengués, ces travaux visent à analyser la perception des pêcheurs sur les interactions entre leurs pratiques et leur environnement dans la partie haute du bassin du Maroni, au coeur de la forêt tropicale de Guyane française où la pêche de subsistance est encore très présente. Nous avons évalué le ressenti des pêcheurs des deux ethnies issues de sept villages (Pidima, Antecume-Pata, Twenké, Kayodé, Elahé, Papaïchton, Loca) concernant l’évolution de leur relation avec le fleuve en les interrogeant sur l’état des ressources naturelles, leurs méthodes de pêche, les activités à proximité et leur mode de vie. Nous avons choisi pour cela une approche d’entrevue semistructurée, avec des thèmes prédéfinis mais sans ordre précis, sous forme de questions ouvertes. La structuration de leur point de vue a été co-construite à l’aide de la cartographie cognitive pour définir les liens existant entre les concepts proposés ainsi que le sens et la force de leurs interactions. L’ensemble des cartes ainsi obtenues a été agrégé en vue de faire ressortir les opinions les plus partagées. Cette carte générale synthétique, peu lisible, a été soumise à différents filtres soit en ne retenant que les opinions les plus fréquemment évoquées, soit en généralisant les concepts à l’aide d’une ontologie hiérarchique, soit en analysant qu’une partie de la carte généralisée en fonction du questionnement scientifique (Cartographie cognitive contextuelle). Nous avons vérifié au préalable, grâce à un test de saturation, que le nombre d’enquêtes effectuées (45) était bien représentatif des différents points de vue de l’ensemble des pêcheurs du haut Maroni. Nous avons constaté qu’en dépit des groupes ethniques (Aluku vs Amérindiens) ou des modes de vie (subsistance vs économie de marché), la plupart des pêcheurs partageaient largement les mêmes opinions. Leur perception principale est que la pêche est menacée par l’extraction illégale de l’or, par l’utilisation croissante des filets de pêche monofilament et par une perte de connaissances de la biologie et du comportement des poissons par les jeunes générations de villageois. En parallèle, les pêcheurs perçoivent un changement constant de leur rôle et de leur relation avec les ressources halieutiques : ils pratiquent de plus en plus une pêche à visée commerciale dans un contexte où le fleuve, et son environnement forestier, n’est plus la seule source de nourriture. Une analyse détaillée des arguments avancés lors de la perception de ces menaces montre que ce processus provient majoritairement d’une occidentalisation mal maîtrisée (scolarisation, monétarisation de l’économie, accès à des biens de consommation…) qui entraîne un changement douloureux des modes de vie des populations locales, en particulier des Amérindiens. Dans ce travail, nous n’avons pas en-soi découvert de nouvelles menaces ou préoccupations perçues par les habitants du Haut Maroni. Mais nous avons mieux compris la construction intellectuelle de la perception de ces menaces, et surtout, nous les avons mieux formalisées afin de dégager des leviers d’action (meilleure maîtrise du phénomène d’occidentalisation, via un accès raisonné aux technologies et une meilleure adaptation de la scolarité aux traditions halieutiques locales et à l’écologie de l’environnement) pour les gestionnaires de l’environnement, et au-delà les responsables politiques. Pour être efficace et durable, l’utilisation de ces leviers d’action doit nécessairement émerger d’une co-construction entre pêcheurs, consommateurs et gestionnaires de l’environnement, en s’appuyant sur une gouvernance reconnue, à l’image d’un Conseil communautaire de la pêche qu’il faut réinventer. En complément, dans un contexte d’accroissement de la population et d’évolution de la consommation, une étude détaillée de cette transition alimentaire devrait être entreprise rapidement afin de l’intégrer dans le plan de gestion durable des stocks halieutiques de ce territoire

When subsistence fishing meets conservation issues: Survey of a small fishery in a neotropical river with high biodiversity value

International audienceThe inland fisheries sector is central for subsistence in many regions worldwide. The exploitation of fish resources is expected to increase along with the growing human population, with underlying conservation issues in regions with high biodiversity value. The small fishery of the Maroni River, French Guiana, is a hotspot of biodiversity and endemism where resource depletion is suspected. We surveyed 754 boat landings in seven villages located in the upper half of the watershed, representing > 6300 fish during the study period (November 2013 - September 2014). Fishers used canoes with outboard engines almost exclusively (75 %) and fished within 32 km of their villages. Most fish were caught in trammel nets (81 %); the 20 most-landed species represented more than 87 % of catches. Depending on the village, daily catches and biomass averaged 6–14 fish and 1.7−13 kg per boat landing, respectively. Seven control sites located outside of the fishing grounds were fished to identify potential differences in catch per unit effort and fish size. Per 100 m2 of trammel net, mean catches ranged from 4 to 13 and 8–29 fish in the villages and control sites, respectively, while fish biomass ranged from 0.9 to 4 and 3.2−7 kg in villages and control sites, respectively. For all species combined, fish caught at control sites were bigger than those landed in villages. This difference was significant for nine of the most-landed species. Differences in fishing techniques and fish catches between villages illustrated the gradual disappearance of the ancestral subsistence fishing. Our results support indications that the fish community in the upper Maroni River is harvested intensively, address the issue of sustainability of the fishery there, and call attention to the need to conserve the river’s remarkable biodiversity

FG_fish_species_Genotypes

This file contains the individual genotypes table for each of 18 species from French Guiana; and the 111 to 156 SNP markers that were validated through MassARRAY procedure. The molecular resources provided here were developed from samples collected in collaboration with the National Amazonian Park in French Guiana, under the contract R&D_2003_06 and with ethical consideration defined in the convention APA-973-7

Data from: A cost-and-time effective procedure to develop SNP markers for multiple species: a support for community genetics

1.Multi‐species population genetics is an emerging field that provides insight relevant to conservation biology and community ecology. However, to date, this approach is limited to species with available genetic resources. The use of thousands of single nucleotide polymorphism (SNP) markers developed from recent genotyping‐by‐sequencing (GBS) technologies is a roadmap for the study of non‐model species, but remains cost prohibitive when several, distantly related species are involved. 2.We aimed to overcome this issue by using a single HiSeq3000 run of restriction‐site associated DNA sequencing (RAD‐Seq) to retrieve SNP markers for 40 diverse species including plants, invertebrates, fish and mammals. We developed a Python‐based pipeline to isolate ~100‐500 high‐quality SNP markers for each species that could be genotyped through classical PCR amplification methods. To assess the quality of these markers, we validated our approach on ~160 of the characterized SNPs for each of 18 Neotropical fish species from the river Maroni (French Guiana, South America), using the MassARRAY iPLEX platform from Agena Bioscience (San Diego, CA, USA). 3.A run of the pipeline applying stringent filtering parameters enabled the successful design of between 130 and 3492 SNP markers for 30 of the 40 study species. Relaxing pipeline parameters allows for an increase in the number of detected SNPs. Across the 18 species from French Guiana, an average of 85% of markers were successfully amplified, polymorphic, and scored in ≥90% of individuals (~200 individuals per species). The great majority (>98%) of these markers were at Hardy‐Weinberg equilibrium in each sampling site from the river Maroni. 4.This SNP discovery was performed at the cost of ~$US110 for each of the 40 species. Genotyping was performed at the cost of ~$US6000 for each of the 18 fish species with an average of 200 individuals per species. This strategy was found cost‐and‐time efficient to develop hundreds of SNP markers for a large range of non‐model species, which can be used to investigate ecological and evolutionary questions that do not require whole‐genome coverage