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WOS:000558450600011; International audience; Owing to difficulties in accessing the vast open ocean, the beta (β) diversity of pelagic fish assemblages remains poorly studied. We investigated the relationship between assemblage similarity and geographical distance between anchored fish aggregating devices (FADs), sampled by standardised underwater visual censuses in three anchored FAD arrays in the Indian Ocean—at the Maldives, the Seychelles and Mauritius. The use of two complementary indices of β-diversity, based on presence/absence data (Jaccard similarity coefficient) and abundance data (Bray–Curtis index), revealed that geographical distance between sampling sites (from 4 to 257 km) appeared to have no effect on the similarity of fish assemblages associated with FADs within each array. The results of this preliminary study question the generalisation of the paradigm of an increase in β-diversity with geographic distance to the open-ocean fish community. Large-scale studies using a variety of datasets should be conducted to further investigate patterns of β-diversity in the open ocean.

Background: In French Polynesia, thyroid cancer mortality and incidence is reported to be the highest in the world. Excessive levels of non-essential trace elements (nETE) in the body are associated with several types of cancer. Objective: The present study aims to provide quantitative information on food contamination by mercury (Hg), lead (Pb), arsenic (As) and cadmium (Cd) in French Polynesia and its potential correlation with measurements performed in fingernails of Polynesians, and then to investigate the potential association between these nETE and different thyroid cancer risks. Methods: The study population included 229 interviewed cases and 373 interviewed controls We performed a descriptive analysis of Polynesian food and examined the association between thyroid cancer risk and daily intake levels of nETE and with fingernail nETE levels. Results: Hg contamination was mainly present in sea products, Pb contamination was present in almost all samples, Cd was detectable in starchy food and As was detectable in all sea products. No patient exceeded dietary contamination WHO limits for Pb, 2 participants exceeded it for Hg and 3 individuals (0.5%) for cadmium. In fingernail clippings, the most detectable pollutant was Pb (553 participants), then Hg (543 participants) then Cd (only in 130 participants). Thyroid cancer risk was increased more than 4 times by Pb daily intake in patients with a history of cancer in first-degree relatives than in ones without (p for interaction =0.01), and 2 times more in women with more than 3 pregnancies than in those with none or less (p for interaction =0.005); it was also increased following As intake by more than 30% in patients with a history of cancer in first-degree relatives than in ones without (p for interaction =0.05). Conclusion: Locally produced foods are not a source of nETE exposure in French Polynesia. Dieatry nETE exposure and fingernail nETE concentration are not associated to differentiated thyroid cancer risk. No correlation found between nETE dietary exposure and fingernail nETE concentration.

Nearshore Fish Aggregating Devices (FAD) have been identified as one of the most practical means for improving food security, in particular in developing and intermediate countries. However, there is still a lack of knowledge regarding the pros and cons of introducing nearshore FADs in shallow coastal waters. This is particularly the case in areas such as the Persian Gulf where traditional handline fisheries supply daily food for local coastal communities. In this context, experimental anchored nearshore FADs were deployed in the north of the Persian Gulf in order to offer a preliminary assessment regarding their possible impact in terms of both catch efficiency and ecological perspectives. CPUE, biodiversity and catch composition were compared at fishery sites with or without FADs between two fishing seasons in the Persian Gulf. Total catches were relatively well balanced between sites using nearshore FADs or without FADs, and between fishing seasons. In contrast, our analysis suggests that the fish species diversity was lower for FAD fishing operations, than for non-FAD fishing. The main differences in the fish assemblages caught between FAD and non-FAD fishing sites were mainly due to pelagic species (e.g. Scomberoides commersonnianus, Caranx sexfasciatus and Acanthopagrus latus), some of which are considered as endangered species (Scomberomorus commerson). Pelagic species were more abundant in non-FAD fishing operations, suggesting that anchored FADs used in these nearshore waters had an effect similar to that of artificial reefs, favouring the transfer of fishing effort from the pelagic to the benthic resources.

International audience; Background. Reconstruction of radiation doses to the thyroid for a case-control study of thyroid cancer in French Polynesians exposed to radioactive fallout from atmospheric nuclear weapons tests during childhood and adolescence faced a major limitation on very little availability of information on lifestyle of French Polynesians in the 1960s–1970s.Method: We use the focus group discussion and key informant interview methodology to collect historical, for the 1960s–1970s, data on behavior and food consumption for French Polynesia population exposed to radioactive fallout from nuclear weapons tests conducted between 1966 and 1974.Results. We obtained archipelago-specific data on food consumptions by children of different ages and by pregnant and lactating women during pregnancy and breastfeeding and behaviour, including time spent outdoors and type and construction materials of residences.Conclusions. This article presents the first detailed information on several key aspects of daily life on French Polynesian archipelagoes during the 1960s–1970s impacting radiation exposure. Important behavior and food consumptions data obtained in this study are being used to improve the radiation dose estimates and to update the risk analysis reported earlier by correcting biases from previous assumptions and by providing better estimates of the parameter values important to radiation dose assessment.

It is estimated that fish aggregating devices (FADs) are now used for over 40% of world tropical tuna catches, making this technique a major phenomenon for high seas fisheries worldwide, and one that has experienced great expansion over the past three decades. The question of whether the FAD is a good or a bad tool for the exploitation of marine resources depends on many parameters. To respond to this question, it is necessary to distinguish different scales of exploitation (artisanal vs. industrial) and various types of FADs (anchored vs. drifting), but it is also very important to gather more data and conduct further research on this topic to gain a better understanding of the phenomenon and of its impacts. As such, twelve years after the first international conference devoted to FADs, which was held in Martinique (French West Indies), a new multi-scalar global assessment of FAD fisheries development and a review of the progress of research in this field was deemed vital. The latest international conference, "Tuna Fisheries and Fish Aggregating Devices", was held in Tahiti in November 2011, and it was an event that welcomed nearly 150 conference attendees from 40 different countries, three ocean regions, and the Mediterranean. This is an analysis of the relevant literature gathered by the author in the bibliographic database FADBASE. Then, the major issues already addressed by the scientific community are set out, and gaps and research priorities are highlighted for anchored and drifting FADs management.

Silky sharks, Carcharhinus falciformis (Muller and Henle, 1839), are the primary elasmobranch bycatch species in tuna purse seine fisheries throughout the world's major oceans. Juveniles of this species commonly associate with drifting fish aggregating devices (Fads) deployed to enhance tuna catches in these fisheries. Here we present results from the first investigation into the behavior of juvenile silky sharks associated with drifting Fads in the western indian ocean. A total of 10 silky sharks were tagged with coded acoustic transmitters around drifting Fads equipped with acoustic receivers. Following release, all sharks undertook an excursion away from the Fad with which they were associated. Two individuals were subsequently never detected, while the initial absence period of the eight detected sharks ranged between 0.1 and 3.5 d. After returning, total association times averaged 5.19 d (sd = 3.15 d) and related horizontal movement rates ranged from 8 to 50 km d-1. Short excursions away from the Fad were undertaken by some individuals, all of which lasted a few hours and were made at night. During periods of association, silky sharks typically occupied the upper 35 m of the water column for the majority of the observation period. These results provide new insights into our understanding of associative behaviors. Further studies are needed to improve assessment of the impacts of Fads on the ecology of this species, a major concern considering the large number of Fads deployed.

Dolphinfish (Coryphaena hippurus), large pelagic predators and important fishery targets, frequently associate with floating debris or manmade fish aggregating devices (FADs). We tagged 8 dolphinfish with pressure-sensitive ultrasonic transmitters and actively tracked individuals continuously for up to 40 h to elucidate the vertical movement patterns and differences between FADassociated (FAD-A) and FAD-unassociated (FAD-U) fish. Four additional fish were equipped with acoustic transmitters and passively monitored for several days with receivers attached to FADs. When not associated with FADs, dolphinfish used the upper 75-100 m of the water column during the day and made descents up to 160 m during the night. In contrast, FAD-A fish generally stayed within the upper 10 m of the water column and tended to make deeper excursions during the day rather than at night. Water temperature data from expendable bathythermo-graphs deployed during active tracking showed that fish only descended to depths where temperatures were

We studied the foraging rhythms of green sea turtles Chelonia mydas on the seagrass beds of N'Gouja Bay, Mayotte Island (Comoros Archipelago) with acoustic transmitters and moored listening stations. We monitored 8 tagged turtles (4 probable males, 3 probable females and 1 immature), from 70 to 109 cm curved carapace length (CCL), for durations ranging from 5 to 92 d. The turtles exhibited a regular diel pattern: they foraged mainly during the day (on average 87% of seagrass detections were between 06:00 and 18:00 h) and rested on the inner reef slope during the night. Night time feeding activities were observed on the seagrass bed when the night light was high. The presence of turtles on the seagrass bed at night was significantly correlated with a night light index (r = 0.54, p = 0.002), which included both moon light and cloudiness indices. Behaviour of the only immature individual observed was similar to adult turtles, although it rested more frequently around noon. All turtles displayed a high fidelity to 1 foraging site within the seagrass bed. Acoustic transmitters and permanent listening stations are an appropriate technique for long-term behavioural studies of turtles, with no human interaction with turtles during tracking, and represent a suitable technique to assess the possible effects of environmental changes or human activities upon green turtle behaviour.

Monitoring the abundance of green turtles (Chelonia mydas) is necessary to assess population trends and risks of collapse. This note presents a study aimed at comparing three techniques for the direct estimation of green turtle numbers in their foraging habitats (seagrass beds and reef flats). The experiment was carried out at Mayotte Island, Western Indian Ocean. The techniques involved were surveys by snorkel, and aerial surveys using a microlight aircraft and a paramotor. Each technique had shortcomings and advantages. While each technique provided estimations of turtle numbers only surveys by snorkel permitted identification of species and sex, whenever visibility and turtle behaviour permitted. Along the shorelines, and over foraging areas, the paramotor was found to be most suitable for direct estimations of turtle numbers. The major advantage of this technique lied in its capability to obtain a synoptic snapshot of turtle distribution over foraging areas. Linear surveys from a microlight aircraft are better suited to monitor foraging areas located further away from the shore., Le suivi de l'abondance de tortues vertes (Chelonia mydas) est nécessaire pour évaluer l'évolution et éventuellement, le risque d'extinction des populations. L'objectif de cette expérience est de comparer trois techniques d'observation permettant l'évaluation directe de l'abondance totale de tortues vertes sur les aires d'alimentation (herbiers et platiers récifaux). L'étude a été conduite à l'île de Mayotte (ouest de l'océan Indien). Les techniques testées sont le comptage sous-marin et les comptages aériens à partir d'un ultra léger motorisé (ULM) et d'un paramoteur. Les limites de chaque technique utilisée ont été mises en évidence. L'abondance totale des tortues a été estimée par les trois techniques. Seuls, les comptages sous-marins ont permis de préciser des caractéristiques biologiques tels que l'espèce et le sexe, lorsque les conditions de visibilité et le comportement des tortues le permettaient. Le paramoteur paraît le plus adapté pour une estimation directe de l'abondance sur les aires d'alimentation situées à proximité immédiate de la côte. Cette technique permet de disposer d'un état de la répartition des tortues sur les aires d'alimentation à un moment donné. Pour les zones d'alimentation plus éloignées de la côte, l'usage de l'ULM est nécessaire pour réaliser les comptages à partir de transects linéaires.

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.

This work aims to define a typology of trawler f1eet in Sète, the main fishing harbour along the French Mediterranean coast, using several multivariate analysis methods. The fishing ships taken to account are represented by annual profiles of landing specific compositions. Five fishing strategies have been identified. A segmentation method using symbolic objects allows a formaI characterisation of the different strategies. These strategies are studied according to several general characteristics usually used for management rules elaboration (power, length, ship age). The typological analysis allows to characterise two main exploitation ways, one directed to the catch of a few species (Engraulis encrasicolus, Sardina pilchardus), the other characterised by the exploitation of a great diversity of species. By this way, it is possible to estimate how the catch of low represented species can significantly contribute to the exploitation of a resource., Cette étude s'appuie sur l'utilisation successive de plusieurs méthodes d'analyses multivariées pour réaliser une typologie de la flottille chalutière du port de Sète, principal port de pêche français de la Méditerranée. Les unités de pêche étudiées sont représentées à l'aide d'un profil annuel de la composition spécifique de leurs débarquements. Cinq stratégies de pêche ont ainsi pu être identifiées. La mise en oeuvre d'une méthode de segmentation permet une caractérisation formelle de ces différentes stratégies à l'aide d'objets symboliques. Les stratégies sont étudiées en référence à plusieurs caractéristiques générales couramment utilisées en gestion des flottilles de pêche (puissance, longueur, âge du bateau, etc.). L'analyse typologique mise en oeuvre au cours de l'étude permet de caractériser nettement deux grandes logiques d'exploitation, l'une orientée vers la recherche d'un très petit nombre d'espèces (Engraulis encrasicolus, Sardina pilchardus), l'autre déterminée par une grande diversité des captures. Elle permet également d'apprécier comment les captures d'espèces peu représentées dans certaines stratégies peuvent contribuer significativement à l'exploitation d'une ressource

This study provides a baseline measure of pelagic fish species diversity around fish aggregating devices (FADs) in the Western Indian Ocean. Using data from visual censuses made by SCUBA divers around drifting FADs we (1) analysed 11 diversity indices describing 4 main compo- nents of pelagic diversity: number of species, evenness, taxonomic diversity and rarity and (2) dis- cussed the viability of using visual censuses around FADs to monitor temporal and spatial changes in diversity patterns of pelagic fishes in the future. Our results not only show that a single index, such as species richness or the Shannon-Wiener index, cannot provide a complete description of pelagic fish diversity around FADs, but also that some components of diversity appear to be multifaceted themselves and require the simultaneous use of several complementary indices in order to be accu- rately described and monitored. Despite a limited sampling effort, our results suggest that using visual censuses around FADs could provide reproducible 'relative' indices of diversity for a well- delimited assemblage of species (intra- and extranatant species in the epipelagic domain). In this con- text, we propose a preliminary 'short list' of diversity indices based firstly on their complementarity and secondly on their simplicity. While visual censuses of pelagic fishes at FADs (like any other sam- pling method) cannot give an exhaustive picture of diversity, they are a fishery-independent survey method that can complement other sampling techniques and provide reproducible information to monitor the diversity of these very difficult-to-access pelagic fish communities.

We adapted a visual census method, mainly used in demersal and reef fish studies, to characterize fish communities associated to drifting fish aggregating devices (FADs) in the Western Indian Ocean. Drifting FAD associated fishes from both equatorial (Seychelles) and tropical waters (Reunion Island) were examined by divers. A total of 32 species (belonging to 16 families) were observed associated with drifting FADs in equatorial waters, and 24 species (14 families) were found around FADs in tropical waters. Twenty species were found in both regions. The highest number of species observed at a single FAD was 18 (12 +/- 2, mean +/- SD) in equatorial and 13 (10 +/- 3) in tropical waters, not counting circumnatant species loosely associated with the FAD. Some species like Kyphosus vaigiensis, Canthidermis maculata, Elagatis bipinnulata, Acanthocybium solandri and Coryphaena hippurus were observed on all or most of the surveys. In this study, the contribution in biomass of the 18 common species associated with drifting FADs (but excluding circumnatant species), represents more than 98% of the biomass. The overall biomass values of closely associated species remains well below tuna biomass estimates for circumnatant tuna schools at FADs, estimated as high as 200 tons. The species that most significantly contribute to the by-catch in tuna purse-seines logically match those that showing the highest biomass values in our surveys (Carcharhinus spp., Elagatis bipinnulata, Coryphaena hippurus, Canthidermis maculata, and Acanthocybium solandri). One of the most abundant and ubiquitous species in our study was the spotted oceanic triggerfish Canthidermis maculata that sometimes formed massive schools of many thousands individuals around the drifting FADs. Future research is needed to explore the role of such non tuna species in the attraction and aggregation processes of tuna around drifting FADs.

To study the behavior of dolphinfish (Coryphaena hippurus) around drifting Fish Aggregating Devices (FADs), we tagged individuals with long-lived, coded sonic transmitters and attached automated sonic receivers to drifting FADs in two regions of the Western Indian Ocean. Among the three tagging methods used in this study (surgery, external hooks, underwater bait without capture), the latest resulted in residence times significantly shorter than the other ones, likely due to regurgitation. Dolphinfish tagged with the two other methods usually stayed several days associated to FADs (Kaplan-Meier survival analysis 5.09 days, mean 6.25 days, SD 4.39 days, maximum 15.26 days), drifting with them. There was no significant difference in the residence times of dolphinfish in equatorial and tropical areas. While associated to FADs, dolphinfish spent most of their time close to floating object (< 365 m). The total time spent away from FADs was low (median 8%), and likely corresponded to making feeding excursions. Dolphinfish did not form a single school while associated to a given FADs, but formed multiple small schools. FADs are likely to be sites with exchanges of individuals between schools. These results are discussed in regards to the possibility of FADs acting as ecological traps and the validity of meeting-point hypotheses as an explanation for fish aggregations under floating objects.

Automated acoustic receivers are now widely used by biologists to study the behavior of fish. However, currently available acoustic receivers require physical recovery of the units to download stored data. Such operation is often difficult in remote study areas like in the open ocean. We present a new satellite-linked acoustic receiver (Vemco VR3-Argos) that allows downloading data through a satellite uplink (Argos). The VR3-Argos can last up to one year, sending GPS positions and tag data at regular time intervals. We illustrate the advantages of this new technology with tagging data from 121 fish of seven species (yellowfin tuna, bigeye tuna, skipjack tuna, wahoo, dolphinfish, silky shark and oceanic triggerfish) caught and released around drifting fish aggregating devices (FADs) in the Western Indian Ocean, far from any land. In opposition with the classic acoustic receivers (Vemco VR2), the use of VR3-Argos allowed to collect data for several weeks after leaving the drifting FADs. Maximum residence times of 3 days for bigeye tuna, 7 days for skipjack, 8 days for wahoo, 10 days for silky shark and 15 days for yellowfin tuna, dolphinfish and oceanic triggerfish could be recorded. VR2 and VR3-Argos are equivalent in terms of quality of residence times data, however depth data obtained through satellites are aggregated in 8 classes for compression purposes, which leads to a loss of precision available with raw data. Future directions of this technology are discussed. des zones eloignees. Les recepteurs acoustiques automatiques sont maintenant largement utilises par les biologistes pour etudier le comportement des poissons. Cependant, les recepteurs acoustiques actuellement disponibles necessitent leur recuperation physique pour charger leurs donnees. Cette operation est souvent difficile dans des zones d'etude eloi- gnees comme en haute mer. Nous presentons un nouveau recepteur acoustique avec liaison satellite (Vemco VR3-Argos) qui permet de recuperer les donnees a travers une liaison satellite (Argos). Le VR3-Argos peut fonctionner plus d'un an, envoyant des donnees GPS et des donnees de marques a intervalles reguliers. Nous illustrons les avantages de cette nou- velle technologie avec des donnees de marquage de 121 poissons de 7 especes differentes (thon albacore, thon obese, listao, thazard, coryphene, requin soyeux, baliste oceanique) captures et relâches autour de dispositifs de concentration de poissons (DCP) derivants dans l'Ouest de l'ocean Indien, loin de toute terre. Au contraire des recepteurs acoustiques classiques (Vemco VR2), l'utilisation du VR3-Argos permet de recolter des donnees plusieurs semaines apres avoir quitte les DCP. Des temps de residence maximum de 3 jours pour le thon obese, 7 jours pour le listao, 8 jours pour le thazard, 10 jours pour le requin soyeux, et 15 jours pour le thon albacore, la coryphene et le baliste oceanique ont pu etre enregistre. Les VR2 et VR3-Argos sont equivalents en termes de qualite de donnees de temps de residence, mais les donnees de profondeur de nage des poissons, obtenues par liaison satellite, sont agregees en 8 classes pour des soucis de compression, ce qui amene a une perte de precision disponible dans les donnees brutes. Les futurs developpements de cette technologie sont discutes.

We conducted displacement experiments using acoustic tags to study the orientation abilities of dolphinfish (Coryphaena hippurus) around FADs. Eleven fish were passively monitored using coded transmitters and acoustic receivers attached to FADs, while seven others were actively tracked with a vessel using continuous acoustic tags equipped with pressure sensors. All these 18 dolphinfish were captured close to a FAD and released between 70 and 1720 m from it. Five fish out of the 14 that were displaced at more than 360 m from a FAD ( estimated detection range of our acoustic receivers, defining the target area during our experiment) returned to the target area. With one individual successfully returning to the target area after having been released at 1600 m from the FAD, the rate of return of fish released up to this distance was significantly higher than expected if they were moving at random, but many fish released at intermediate distances moved in other directions. Based on detailed statistical analysis of the return score, we estimated that dolphinfish are able to orientate towards a FAD area from at least 820 m. The connection between our definition of the target area and the association area of dolphinfish around a FAD is discussed, as well as the impact of stress and motivation in the rates of return observed. More experiments should be conducted to improve this first estimate. Specific experiments should also be designed to more accurately determine the association range of fish around FADs and their motivation to orientate towards FADs.

Yellowfin tuna (Thunnus albacares) are known to preferentially occupy the Surface mixed layer above the thermocline and it has been Suggested that they are physiologically restricted to water lerriperatt.11-CS no more than 8 degrees C colder than Surface waters. However, we here report for dive data acquired from a large yellowfin tuna which demonstrate for the first time that this species is indeed capable of making prolonged dives into deep cold waters. A yellowfin tuna (134 cm fork length) caught near ail anchored fish aggregating device (FAD) in the Seychelles (Western Indian Ocean) was equipped with all internally implanted archival tag and released. The fish was recaptured 98 days later. As predicted for this species, this fish spent 85% of its time shallower than 75 in (maximum thermocline depth experienced by the fish) but, over the Course of the track, it performed three deep dives to 578 in, 982 In and 1160 In. Minimum ambient water temperatures recorded Lit these depths were 8.6 degrees C, 7.4 degrees C and 5.9 degrees C respectively and varied by up to 23.3 degrees C from surface temperatures. The fish spent 8.3% of its time in waters more than 8 degrees C colder than the surface layer and daily experienced a wide range of sea temperatures (mode at 15- 16 degrees C) and of temperatures of the gut cavity (mode at 6 degrees C). The reason for these dives call not be known. These depths and temperatures significantly exceed those reported ill the literature so far and clearly demonstrate that this species has the physiological and behavioral ability to penetrate deep cold sections of the ocean.

Daily growth increments measured in the otolith of Thunnus atlanticus were used to estimate the age and growth of individuals. which were sampled from an artisanal fishery operating around fish aggregating devices (FADs) moored off Martinique Island. In this study, 76 otoliths were analysed for fish ranging from 20 to 68 cm fork lengths (FL). The fish were caught using trolling lines at depths ranging from 0 to 10 m. Counts were made, under a light microscope, on the external part of the transverse section of the sagittae, from the primordium to the ventral edge. The mean coefficient of variation of the age reading was 2.4%. To validate readings, the number of increments for 11 individuals was counted using both optic and scanning electron microscopes. The calculated relationship between readings of both methods was found to be linear, with a slope of 1.03 and R-2 = 0.99. Frequency of growth increment formation could not be validated. Growth rates derived from otolith readings were, however, compared to those obtained using a modal progression analysis, which was performed on the length-frequency distributions of the landings over a period of two months. The corroboration between the growth rates was good. One increment was assumed to represent one day. The parameters of the von Bertalanffy growth curve for both sexes were L-infinity = 71.4 cm FL, k = 0.002 day(-1) and tau(0) = -80 days. According to our results, there is no evidence that Martinican moored FADs act as ecological traps for blackfin tuna. Instead, young blackfin tuna probably leave the vicinity of Martinican moored FADs to undergo a trophic migration at 7 to 8 month-old, and then come back about 8 months later to breed in the Lesser Antilles area., Les microstructures présentes dans les otolithes de Thunnus atlanticus ont été utilisées pour estimer l'âge et la croissance des thons capturés par la pêcherie artisanale exploitant les dispositifs de concentrations de poissons (DCP) mouillés autour de la Martinique. Des thons de 20 à 68 cm de longueur à la fourche (LF) ont été capturés à la ligne de traîne de surface entre 0 et 10 m de profondeur. Les stries d'accroissement ont été comptées sur 76 otolithes en microscopie optique sur la partie externe des coupes transversales de la sagitta, du nucléus jusqu'à l'extrémité verticale de la coupe (coefficient de variations 2,4 %). Afin de vérifier qu'il n'y avait pas de sous-estimation du nombre de stries, nous avons effectué un comptage, en microscopie électronique à balayage, pour 11 individus. La relation établie entre ces deux méthodes de comptage est linéaire avec un pente égale à 1,03 et R2 = 0,99. La vitesse de croissance issue de l'analyse des otolithes a été comparée à celle estimée à partir de l'analyse en progression modale des distributions en fréquence de taille des débarquements sur une période de 2 mois. La corroboration entre les deux méthodes était bonne. Nous avons supposé que la formation des stries de croissance suivait un rythme journalier. Les paramètres de l'équation de croissance de von Bertalanffy pour les 2 sexes confondus sont: L-infinity = 71.4 cm FL, k = 0.002 day(-1) and tau(0) = -80 days. Les résultats de cette étude n'indiquent pas que les DCP ancrés martiniquais puissent agir comme des pièges écologiques pour les thons noirs. Les jeunes thons noirs semblent au contraire quitter la proximité des DCP et entreprendre une migration trophique lorsqu'ils atteignent 7 à 8 mois. Ils ne reviendraient ensuite dans la zone des Petites Antilles qu'environ 8 mois plus tard, manifestement pour se reproduire.