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Background: The biological information of fish, which include reproduction, is the prerequisite and the basis for the assessment of fisheries. Methods: The aim of this work was to know the reproductive biology with the first sexual maturity (TL50) and the spawning period for 58 mainly fish species in the waters around La Réunion Island (Western Indian Ocean). Twenty families belonging to the Actinopterygii were represented (acanthuridae, berycidae, bramidae, carangidae, cirrhitidae, gempylidae, holocentridae, kyphosidae, labridae, lethrinidae, lutjanidae, malacanthidae, monacanthidae, mullidae, polymixiidae, pomacentridae, scaridae, scorpaenidae, serranidae, sparidae; 56 species; n = 9,751) and two families belonging to the Elasmobranchii (squalidae, centrophoridae; 2 species; n = 781) were sampled. Between 2014 and 2022, 10,532 individuals were sampled covering the maximum months number to follow the reproduction periods of these species. Results: TL50 for the males and the females, respectively, ranged from 103.9 cm (Acanthurus triostegus ) to 1,119.3 cm (Thyrsitoides marleyi ) and from 111.7 cm (A. triostegus ) to 613.1 cm (Centrophorus moluccensis ). The reproduction period could be very different between the species from the very tight peak to a large peak covered all months. Conclusions: Most species breed between October and March but it was not the trend for all species around La Réunion Island.

As part of the monitoring of commercial species targeted by fisheries in the outermost regions, Ifremer has developed the Accobiom project (ACquisition de COnnaissances sur les paramètres Biologiques des ressources marines exploitées en Outre-Mer) in order to improve knowledge of fish stocks in the overseas territories. In the future, once sufficient in quantitative and temporal terms, these data will make it possible to reconstitute life history traits on the scale of the total population (size-weight relationship, size-age relationship, ogive of sexual maturity, size and age of first sexual maturity, reproduction period) and to make a diagnosis of the stocks. Financed by the French Development Agency (AFD) and implemented by Ifremer between 2021 and 2022 in four overseas departments (Guadeloupe, Martinique, French Guiana and Reunion Island), this project involved the drafting of a sampling protocol and the associated data collection, the analysis of the biological data collected (size, weight, age, sex, sexual maturity phase) as well as methodological developments allowing the integration of these new data into the assessment models of the main fish stocks of the DOMs, identified under the Data Collection Framework (DCF) regulation (EU) n°2017/10041. This document is therefore the methodological guide concerning the acquisition, validation, logistics and banking of the associated data. It builds on several documents already produced in the context of other sampling (Badts & Bertrand, 2012; Elleboode, Badts, Telliez, et al., 2022; Elleboode, Telliez, Aumond, et al., 2022; Elleboode, Badts, Prigent, et al., 2022; Garren et al., 2019; Scientific, Technical and Economic Committee for Fisheries (STECF), 2020), Dans le cadre du suivi des espèces commerciales ciblées par la pêche dans les RUP (régions ultrapériphériques), l’Ifremer a élaboré le projet Accobiom (ACquisition de COnnaissances sur les paramètres Biologiques des ressources marines exploitées en Outre-Mer) afin de renforcer les connaissances sur les stocks halieutiques en Outre-mer. A l’avenir, une fois suffisantes en termes quantitatifs et temporels, ces données permettront de reconstituer les traits d’histoire de vie à l’échelle de la population totale (relation taille-poids, relation taille-âge, ogive de maturité sexuelle, taille et âge de première maturité sexuelle, période de reproduction) et de porter un diagnostic sur les stocks. Financé par l’Agence Française de Développement (AFD) et mis en œuvre par l’Ifremer entre 2021 et 2022 dans quatre départements d’Outre-Mer (DOM) (Guadeloupe, Martinique, Guyane et La Réunion), ce projet prévoyait la rédaction d’un protocole d’échantillonnage et la collecte de données associée, l’analyse des données biologiques collectées (tailles, poids, âge, sexe, phase de maturité sexuelle) ainsi que des développements méthodologiques permettant d’intégrer ces nouvelles données aux modèles d’évaluation des principaux stocks de poissons des DOM, identifiés au titre du règlement Data Collection Framework (DCF) (UE) n°2017/10041. Ce présent document est donc le guide méthodologique concernant l’acquisition, la validation, la logistique et la bancarisation des données associées. Il s’appuie sur plusieurs documents déjà réalisés dans le cadre d’autres échantillonnages (Badts & Bertrand, 2012; Elleboode, Badts, Telliez, et al., 2022; Elleboode, Telliez, Aumond, et al., 2022; Elleboode, Badts, Prigent, et al., 2022; Garren et al., 2019; Scientific, Technical and Economic Committee for Fisheries (STECF), 2020).

A l’aide de données de vidéos sous-marines et de pêches, le projet IPERDMX a permis de caractériser l'état de santé et la dynamique des stocks de poissons démersaux, épipélagiques et benthopélagiques à l’échelle des différents habitats exploités (récifaux et profonds) autour de l’île de La Réunion, au regard des pressions de pêche et en tenant compte de la présence des Aires Marines Protégées (AMP). Il a ainsi contribué à compléter les connaissances acquises dans des projets de recherche antérieurs, connaissances indispensables à la compréhension des relations complexes entre les activités humaines et la singularité des écosystèmes récifaux et profonds de l’île de La Réunion, éléments essentiels pour la recherche et l’expertise halieutique. Ce projet a mis en œuvre des protocoles d’étude et de suivi des ressources halieutiques déjà appliqués dans d’autres régions et adaptés aux différents habitats exploités et statuts réglementaires existants, entre 1 et 500 mètres de profondeur, y compris au sein des AMP existantes. Ainsi, une description et un suivi des pratiques des pêches, à pied, sous-marine et embarquée ont été mis en œuvre principalement au niveau de la Réserve Naturelle Marine de La Réunion et de la Réserve de pêche de Sainte-Rose. L'état des ressources ichtyologiques a été évalué en combinant 2 approches complémentaires : 1°/ des comptages par vidéos sous-marines sur les habitats compris entre 1 et 85 mètres de profondeur et 2°/ l’analyse de données de pêche entre 1 et 500 mètres de profondeur. Ces nouvelles données, spatialisées et structurées en taille pour les principales espèces d’intérêt halieutique, contribuent significativement à la connaissance de la diversité et de l'abondance de l’ichtyofaune sur les principaux habitats. Le volet sclérochronologie a permis d'évaluer les paramètres de croissance chez 12 nouvelles espèces locales non encore étudiées précédemment. De plus, les structures populationnelles, permettant de définir les unités de gestion p

Repeated fish handling may cause stress, which biases experiments and so affects the results. In order to reduce this, the present study investigates the benefit of using bioimpedance analysis to estimate morphological parameters. Bioimpedance analysis is a non-lethal and integrative electrical measurement that can be used to estimate several kinds of physiological parameters and is used in medicine and ecological studies. In particular, bioimpedance can monitor the individual growth of fish, which is a prerequisite for most biological and ecological studies, as body size is one of the best predictors for numerous life history traits and ecological parameters. After a short review on the use of bioimpedance measurement in medicine and ecology, we illustrate the potential of bioimpedance spectroscopy, as opposed to single frequency measurement, for experimental studies on fish. Using a monolithic four-contact electrode and a cost-effective portable system, we conducted bioimpedance spectroscopy on 159 sardines. The association between the length, weight, and electrical parameters obtained at different frequencies from the bioimpedance spectroscopy was investigated. Our results show that accounting for more than one frequency substantially improves the prediction of length and weight. We conclude that bioimpedance could potentially be a powerful tool for monitoring fish growth in ecological studies.

This poster presents the reproductive cycle during the 12 months of the year (with the fish proportions : during peak reproduction, able to reproduce and the sexual rest). Total length and Age at the first sexual maturity of the main demersal species exploited around Reunion Island (Indian Ocean) are identified. These data were carried out and analysed during the European research project IPERDMX (2019-2022) which aims to specify the state of the exploited populations in the different habitats around the Reunion Island (Indian Ocean), and thus contribute to the stock assessment of demersal fish. These biological data are presented for 17 species: Deep-water red snapper (Etelis carbunculus), Bluestriped snapper (Lutjanus notatus), Goldbanded snapper (Pristipomoides multidens), Oblique-banded grouper (Epinephelus radiatus), Common bluestripe snapper (Lutjanus kasmira), Rusty jobfish (Aphareus rutilans), Brilliant pomfret (Eumegistus illustris), Alfonsino (Beryx decadactylus), Crimson jobfish (Pristipomoides filamentosus), Bluefin trevally (Caranx melampygus), Yellow-edged lyretail (Variola louti), White-edged lyretail (Variola albimarginata), Green Jobfish (Aprio virescens), Blacktip grouper (Epinephelus fasciatus), Golden hind (Cephalopholis aurantia), Spotcheek emperor (Lethrinus rubrioperculatus) and Ornate jobfish (Pristipomoides argyrogrammicus)., Ce poster présente les périodes de reproduction et les caractéristiques du poisson (taille et âge moyens) lors de la première maturité sexuelle des principales espèces démersales exploitées autour de l'Ile de La Réunion. Ces données ont été acquises et analysées lors du projet européen de recherche IPERDMX (2019-2022) qui vise à préciser l’état des peuplements exploités dans les différents habitats à l’échelle de la pêcherie de l'Ile de La Réunion (Océan Indien), et ainsi contribuer à l'évaluation des stocks de poissons démersaux. Ces données biologiques sont présentées pour 17 espèces : Vivaneau rubis (Etelis carbunculus), Vivaneau à raies blueus (Lutjanus notatus), Vivaneau à bande dorée (Pristipomoides multidens), Mérou zébré (Epinephelus radiatus), Vivaneau à raies bleues (Lutjanus kasmira), Vivaneau argenté (Aphareus rutilans), Brème noire (Eumegistus illustris), Beryx commun (Beryx decadactylus), Colas fil (Pristipomoides filamentosus), Carangue aile bleue (Caranx melampygus), Croissant queue jaune (Variola louti), Croissant queue blanche (Variola albimarginata), Vivaneau job (Aprio virescens), Mérou oriflamme (Epinephelus fasciatus), Vieille dorée (Cephalopholis aurantia), Empereur honteux (Lethrinus rubrioperculatus) et Colas orné (Pristipomoides argyrogrammicus).

This poster presents the sagittal otoliths of the main demersal species exploited around Reunion Island. These calcified structures in inner-ear are used to estimate the fih ageing and others biological parameters. The otolith shape is an efficient tool to discriminate the stock unit (or management unit) of these species. These data were carried out and analysed during the European research project IPERDMX (2019-2022) which aims to specify the state of the exploited populations in the different habitats around the Reunion Island (Indian Ocean), and thus contribute to the stock assessment of demersal fish. These biological data are presented for 17 species: Deep-water red snapper (Etelis carbunculus), Bluestriped snapper (Lutjanus notatus), Goldbanded snapper (Pristipomoides multidens), Oblique-banded grouper (Epinephelus radiatus), Common bluestripe snapper (Lutjanus kasmira), Rusty jobfish (Aphareus rutilans), Brilliant pomfret (Eumegistus illustris), Alfonsino (Beryx decadactylus), Crimson jobfish (Pristipomoides filamentosus), Bluefin trevally (Caranx melampygus), Yellow-edged lyretail (Variola louti), White-edged lyretail (Variola albimarginata), Green Jobfish (Aprio virescens), Blacktip grouper (Epinephelus fasciatus), Golden hind (Cephalopholis aurantia), Spotcheek emperor (Lethrinus rubrioperculatus) and Ornate jobfish (Pristipomoides argyrogrammicus)., Ce poster présente les otolithes des principales espèces démersales exploitées autour de l'Ile de La Réunion. Ces pièces calcifiées de l’oreille interne des poissons permettent d’estimer leur âge et fournissent aussi de nombreuses informations comme leur forme qui est utilisée pour connaître la répartition des stocks (ou unités de gestion) de ces espèces. Ces données ont été acquises et analysées lors du projet européen de recherche IPERDMX (2019-2022) qui vise à préciser l’état des peuplements exploités dans les différents habitats à l’échelle de la pêcherie de l'Ile de La Réunion (Océean Indien), et ainsi contribuer à l'évaluation des stocks de poissons démersaux. Ces données biologiques sont présentées pour 17 espèces : Vivaneau rubis (Etelis carbunculus), Vivaneau à raies blueus (Lutjanus notatus), Vivaneau à bande dorée (Pristipomoides multidens), Mérou zébré (Epinephelus radiatus), Vivaneau à raies bleues (Lutjanus kasmira), Vivaneau argenté (Aphareus rutilans), Brème noire (Eumegistus illustris), Beryx commun (Beryx decadactylus), Colas fil (Pristipomoides filamentosus), Carangue aile bleue (Caranx melampygus), Croissant queue jaune (Variola louti), Croissant queue blanche (Variola albimarginata), Vivaneau job (Aprio virescens), Mérou oriflamme (Epinephelus fasciatus), Vieille dorée (Cephalopholis aurantia), Empereur honteux (Lethrinus rubrioperculatus) et Colas orné (Pristipomoides argyrogrammicus).

The groupers (Epinephelidae family) are demersal species that are a vulnerable resource due to increasing fishing pressure around Reunion Island. Five species of groupers are among the main species exploited by commercial and recreational fisheries around La Réunion Island: blacktip grouper (Epinephelus fasciatus; Forsskål 1775), oblique-banded grouper (Epinephelus radiatus; Day 1868), golden hind (Cephalopholis aurantia, Valenciennes 1828), white-edged lyretail (Variola albimarginata; Baissac 1953) and yellow-edged lyretail (Variola louti; Fabricius 1775). From 2014 to 2021, a total of 482 individuals were caught. Body length-weight relationships showed a significant relationship between total length and total weight for all species. Among the five grouper species, significant sexual dimorphism was only observed for E. fasciatus. For each grouper species, the von Bertalanffy model gave the best fit for the ageing data. While the unconstrained von Bertalanffy model fitted very well to the data of four species (C. aurantia, E. radiatus; V. albimarginata and V. louti), the Gompertz model gave the best fit for the ageing data of E. fasciatus. The parameters of these growth models gave the asymptotic length TL∞ (from 28.9 cm for C. aurantia to 76.6 cm for V. louti), and growth rate K (from 0.16 for V. albimarginata to 0.40 for E. fasciatus) for each species. Consequently the growth performance index for these grouper species varied from 2.40 to 3.09. Based on gonad observation, the length at first sexual maturity of females varied between 14 to 18 cm for C. aurantia, E. fasciatus and V. albimarginata, to 32 cm for E. radiatus and 34 cm for V. louti. The corresponding age at first sexual maturity by species ranged from 1.67 to 6.65 years old. Reproduction intensity showed that reproduction peaked for a period of three months each year. Three species (C. aurantia; E. fasciatus and V. louti) reproduced mainly in summer, between December to March, while E. radiatus and V. a

Ce rapport constitue une synthèse des livrables des 3 actions des conventions PECHTRAD 2020 & 2021. Ainsi, un soutien scientifique par une contribution aux réunions de médiation et de vulgarisation de la connaissance scientifique auprès des pêcheurs, des gestionnaires et des organismes d’Etat a été réalisé (action 1). La seconde action a synthétisé les résultats des analyses de l’évolution des efforts de pêche et des captures des différents métiers pratiqués par les usagers sur les platiers récifaux gérés par la RNMR en 2020 et 2021. L’évolution des indices annuels de captures par unité d’effort a montré, une diminution globale des abondances, aussi bien de capucins nains pêchés au filet, et des poissons ciblés à la gaulette, que des rendements de zourite (poulpe) au bâton. La troisième action a consisté en un soutien à la collecte des paramètres biologiques sur les espèces récifales capturées par les pêches illégales. La quatrième action sera valorisée au travers d'une publication dans les prochains mois (en préparation).

This poster presents the growth of the main demersal species exploited around Reunion Island based on the relationships established between total length, total weight, age and first sexual maturity. These data were carried out and analysed during the European research project IPERDMX (2019-2022) which aims to specify the state of the exploited populations in the different habitats around the Reunion Island (Indian Ocean), and thus contribute to the stock assessment of demersal fish. These biological data are presented for 17 species: Deep-water red snapper (Etelis carbunculus), Bluestriped snapper (Lutjanus notatus), Goldbanded snapper (Pristipomoides multidens), Oblique-banded grouper (Epinephelus radiatus), Common bluestripe snapper (Lutjanus kasmira), Rusty jobfish (Aphareus rutilans), Brilliant pomfret (Eumegistus illustris), Alfonsino (Beryx decadactylus), Crimson jobfish (Pristipomoides filamentosus), Bluefin trevally (Caranx melampygus), Yellow-edged lyretail (Variola louti), White-edged lyretail (Variola albimarginata), Green Jobfish (Aprio virescens), Blacktip grouper (Epinephelus fasciatus), Golden hind (Cephalopholis aurantia), Spotcheek emperor (Lethrinus rubrioperculatus) and Ornate jobfish (Pristipomoides argyrogrammicus)., Ce poster présente la croissance des principales espèces démersales exploitées autour de l'Ile de La Réunion à partir des relations établies entre la longueur totale, le poids totale, l'age et la première maturité sexuelle. Ces données ont été acquises et analysées lors du projet européen de recherche IPERDMX (2019-2022) qui vise à préciser l’état des peuplements exploités dans les différents habitats à l’échelle de la pêcherie de l'Ile de La Réunion (Océean Indien), et ainsi contribuer à l'évaluation des stocks de poissons démersaux. Ces données biologiques sont présentées pour 17 espèces : Vivaneau rubis (Etelis carbunculus), Vivaneau à raies blueus (Lutjanus notatus), Vivaneau à bande dorée (Pristipomoides multidens), Mérou zébré (Epinephelus radiatus), Vivaneau à raies bleues (Lutjanus kasmira), Vivaneau argenté (Aphareus rutilans), Brème noire (Eumegistus illustris), Beryx commun (Beryx decadactylus), Colas fil (Pristipomoides filamentosus), Carangue aile bleue (Caranx melampygus), Croissant queue jaune (Variola louti), Croissant queue blanche (Variola albimarginata), Vivaneau job (Aprio virescens), Mérou oriflamme (Epinephelus fasciatus), Vieille dorée (Cephalopholis aurantia), Empereur honteux (Lethrinus rubrioperculatus) et Colas orné (Pristipomoides argyrogrammicus).

Body length–weight (L–W) relationships of 123 fish species (122 Actinopterygii and 1 Elasmobranchii) were studied from 10 218 individuals caught around Réunion Island from 2000 to 2021. All species, except for 4 with a very small number of individuals and limited length range, showed a significant relationship between total length and total weight. For 52 species, the data showed the body becoming more elongated (i.e. b < 3.0) over their lifespan, while for 63 species the individuals became thicker (i.e. b > 3.0); only 4 species had a b-value equal to 3.0, signifying isometric growth. Of 72 species for which macroscopic observation allowed identification of sex, there was sexual dimorphism for only 9 species (12.5%), with a significant difference between the slopes of the length–weight relationships. Temporal effects were also investigated, using the annual component of time of capture for 75 species and the seasonal component for 73 species. A temporal effect was significant for 27 species (36.0%) when the sampling year was taken into account, and for 14 species (19.2%) when the sampling quarter (season) was taken into account. Finally, among 120 species tested, the relationship between total length and standard length was significant, and among 114 species the relationship between total weight and gutted (eviscerated) weight was significant.

Ces fiches sur des espèces marines de Méditerranée occidentale sont des documents de terrain d’aide à l'identification. Elles sont principalement établies pour favoriser la qualité et la rapidité d’identification des espèces capturées lors des campagnes halieutiques en Méditerranée. Ces fiches sont donc destinées à des opérateurs avertis. Sans être exhaustif, le domaine couvert par ces fiches correspond à plus de 300 espèces (version 4) de Poissons, Céphalopodes et Crustacés. Ces espèces sont soit pêchées lors des campagnes de chalutages du Golfe du Lion et de l’Est-Corse (à des profondeurs comprises entre 20 à 800 m), soit susceptibles de l’être car référencées/signalées dans la zone. Une fiche regroupe des espèces similaires, leurs principales caractéristiques, et lorsque qu’il existe des possibilités de confusion, présentent les principaux critères discriminants. Ces fiches ne constituent donc pas un manuel d’identification faunistique. L’expérience et le savoir-faire de nombreux intervenants ont permis la constitution de ces fiches, quel que soit leur niveau de contribution, nous les en remercions tous.

The French aerial survey provide an important fisheries independent index for the stock assessment of Eastern Atlantic Bluefin Tuna (EABFT, Thunnus thynnus). However, this survey presents several shortcomings. The main issue is linked to the absence of quantitative estimate of the size of the different school types encountered during the survey. This prevents from accounting to changes in school size composition, which could affect the trends of the index. Since 2016 video cameras were set-up under the aircraft to record the flights and obtain school size estimates. In addition to the 2017 update of the index, the present manuscript describes the procedure to estimate school size from the videos and presents preliminary results for an index integrating this new information. Robustness to school type assignment and school size variability are investigated through bootstrap approaches. The results show distinct surfaces for the different school types and that including school sizes into the index leads to a comparable long-term trend, but with higher values for 2009-2012 than without including the school surfaces., La prospección aérea francesa proporciona un importante índice independiente de la pesquería para la evaluación del stock de atún rojo del Atlántico oriental (EABFT, Thunnus thynnus). Sin embargo, esta prospección presenta diversas deficiencias. El principal problema está relacionado con la falta una estimación cuantitativa del tamaño de los diferentes tipos de bancos hallados durante la prospección. Esto impide tener en cuenta los cambios en la composición por tallas del banco, lo que podría afectar a las tendencias del índice. Desde 2016, se colocaron cámaras de vídeo bajo la aeronave para grabar los vuelos y obtener estimaciones del tamaño de los bancos. Además de la actualización del índice de 2017, el presente documento describe el procedimiento para estimar el tamaño de los bancos a partir de los vídeos y presenta resultados preliminares para un índice que integre esta nueva información. Se investiga la robustez ante la asignación al tipo de banco y la variabilidad en el tamaño del banco mediante enfoques de bootstrap. Los resultados demuestran superficies diferentes para los distintos tipos de bancos y que incluir el tamaño del banco en el índice conduce a una tendencia a largo plazo comparable, pero con valores más elevados para 2009- 2012 que sin incluir las superficies de los bancos., La prospección aérea francesa en el golfo de León proporciona un importante índice independiente de la pesquería para la evaluación del stock de atún rojo del Atlántico este (EABFT, Thunnus thynnus). El presente documento recuerda la metodología empleada para la prospección y proporciona la actualización del índice para el año 2021, que muestra un ligero descenso respecto a 2020, que fue el año con el valor más elevado hasta la fecha, pero ocupa el tercer puesto en cuanto al valor más alto. Lo que confirma la tendencia al alza de los últimos años.

Different dolphin and tuna species have frequently been reported to aggregate in areas of high frontal activity, sometimes developing close multi-species associations to increase feeding success. Aerial surveys are a common tool to monitor the density and abundance of marine mammals, and have recently become a focus in the search for methods to provide fisheries-independent abundance indicators for tuna stock assessment. In this study, we present first density estimates corrected for availability bias of fin whales (Balaenoptera physalus) and striped dolphins (Stenella coeruleoalba) from the Golf of Lions (GoL), compared with uncorrected estimates of Atlantic bluefin tuna (ABFT; Thunnus thynnus) densities from 8 years of line transect aerial surveys. The raw sighting data were further used to analyze patterns of spatial co-occurrence and density of these three top marine predators in this important feeding ground in the Northwestern Mediterranean Sea. These patterns were investigated regarding known species-specific feeding preferences and environmental characteristics (i. e. mesoscale activity) of the survey zone. ABFT was by far the most abundant species during the surveys in terms of schools and individuals, followed by striped dolphins and fin whales. However, when accounted for availability bias, schools of dolphins and fin whales were of equal density. Direct interactions of the species appeared to be the exception, but results indicate that densities, presence and core sighting locations of striped dolphins and ABFT were correlated. Core sighting areas of these species were located close to an area of high mesoscale activity (oceanic fronts and eddies). Fin whales did not show such a correlation. The results further highlight the feasibility to coordinate research efforts to explore the behaviour and abundance of the investigated species, as demanded by the Marine Strategy Framework Directive (MSFD).

Conservation and management measures for exploited fish species rely on our ability to monitor variations in population abundance. In the case of the eastern stock of Atlantic bluefin tuna (ABFT), recent changes in management policies have strongly affected the reliability of fishery-dependent indicators due to drastic changes in fishing season/area, fisheries selectivity and strategy. However, fishery-independent indices of abundance are rare for large pelagic fish, and obtaining them is often costly and labor intensive. Here, we show that scientific aerial surveys are an appropriate tool for monitoring juvenile bluefin tuna abundance in the Mediterranean. We present an abundance index based on 62 aerial surveys conducted since 2000, using 2 statistical approaches to deal with the sampling strategy: line and strip transects. Both approaches showed a significant increase in juvenile ABFT abundance in recent years, resulting from the recovery plan established in 2007. Nonetheless, the estimates from the line transect method appear to be more robust and stable. This study provides essential information for fisheries management. Expanding the spatial coverage to other nursery grounds would further increase the reliability and representativeness of this index.

We describe the total lipid content, lipid class composition and fatty acid profiles of adult forage fishes (anchovy, sardine and sprat) sampled in the NW Mediterranean Sea in 2010 and 2011. Inter-and intra-species differences were mostly related to sampling period with limited effect of gender or total length. As an assemblage, total lipid content and relative levels of triacylglycerols and fatty acids 16:1n7, 20:5n3 and 14:0 in forage fish were highest in summer and autumn, indicating better feeding conditions and a more pronounced diatom-supported food web. In contrast, total lipid content was lowest at the end of winter and spring, and coincided with high levels of 22:6n3, indicating a more herbivorous diet based on dinoflagellates. Resource partitioning and niche separation, as inferred from fatty acid profiles, were apparent between species. Sardine showed a more diverse, temporally separated feeding strategy than anchovy, and dietary overlap was higher in winter than summer with sardine having higher markers of copepods, 22:1n11 and 20:1n9. Sprat collected in winter occupied a separate niche area to both sardine and anchovy with higher total lipid content and carnivory biomarker 18:1n9. Our results show that the lipid dynamics of forage fishes can be used to gain quantitative insights into sub-system level changes in species interactions, including prey and predator productivity.

Here we present an update of the aerial surveys that have been carried out by IFREMER in the western Mediterranean Sea since 2000. This collection of data enables the monitoring of the bluefin juvenile population since the Gulf of Lyon is considered as a nursery for young individuals. The detections of juvenile bluefin tuna are carried out along the same transects between 2000-2003 and then 2009-2011 and are used to calculate a fishery-independent index of bluefin tuna abundance. This index can therefore be included in the stock assessment procedure as an abundance index of juveniles., Nous présentons ici une mise à jour des données de suivis aériens effectués par IFREMER en Méditerranée occidentale depuis 2000. Ces données permettent le suivi de la population de juvéniles de thon rouge car le Golfe du Lion est considéré comme une nourricerie pour ces jeunes individus. Les détections de bancs de thon rouge sont réalisées le long des mêmes transects entre 2000 et 2003 puis de 2009 à 2011 et sont utilisées afin de calculer un indice d'abondance indépendant des données de pêche pour les juvéniles de thon rouge. Cette indice peut ainsi être inclus dans la procédure d'évaluation de stock en tant qu'indice d'abondance des juvéniles., Se presenta una actualización de los datos de prospecciones aéreas efectuadas por IFREMER en el Mediterráneo occidental desde 2000. Estos datos permiten el seguimiento de la población de juveniles de atún rojo ya que el golfo de León es considerado una zona de alimentación para estos ejemplares jóvenes. Las detecciones de los bancos de atún rojo se realizaron a lo largo de los mismos transectos entre 2000 y 2003 y posteriormente de 2009 a 2011 y se utilizan para calcular un índice de abundancia independiente de la pesquería para los juveniles de atún rojo. Este índice puede así incluirse en el procedimiento de evaluación de stock como índice de abundancia de juveniles.

In various experiments under self-feeding conditions, sea bass groups could be divided into three categories regarding feeder actuation: high, low and zero-triggering fish. In all cases few high-triggering fish were responsible for a high percentage of the feed delivery. A question was raised about the role played by feeding motivation in such high-triggering status acquisition. It was approached by applying a 3-week fasting period in order to induce similar negative specific growth rate (SGR) in two groups of fish of similar mean weight but with either a low or a high coefficient of variation for weight (CVw)(T-low: CVw similar to 11%, 3 tanks of 60 fish each; T-high: CVw similar to 20%, 3 tanks of 60 fish each). These groups were created to test the consistency of behavioural responses in two different contexts (i.e. two population size-distributions). During the follow-up period of 40 days, the group level feed-demand behaviour was not strongly modified by the fasting period and there were no differences between T-low and T-high groups. Complete growth compensation was the same in all tanks as observed at the end of the experiment. At the individual level, high-triggering fish were exactly the same individuals before and after the fasting period. Up to four high-triggering fish could be observed according to the tank and when several fish were performing high-triggering activity, their rankings were sometimes reversed after the fasting period. High-triggering fish increased their activity levels after the fasting period showing behavioural plasticity. High-triggering status could neither be explained by an initial lower SGR nor a sex effect, nor by any of the measured physiological blood parameters. Thus, individual's triggering activity levels could be related to personality and/or metabolic traits but further research is required to confirm this assumption. (C) 2011 Elsevier B.V. All rights reserved.

This study aims to test the influence of size grading on self-feeding behaviour, social structure (measured by the percentage of triggering acts per individual), growth performances, and blood physiological variables of individually passive integrated transponder (PIT)-tagged sea bass juveniles, using a computerized on-demand feeding system coupled with a PIT tag monitoring device. Three consecutive periods of 27 days each were compared: a first period (P1) before grading (6 tanks of 100 fish; 40.2 +/- 8.9 g) followed by a second period (P2) after grading. The protocol applied aimed to create two groups of fish of similar mean weight but with either a low or a high coefficient of variation of weight (CV(w)) corresponding to an imposed difference in social disruption (T(low): CV(w) similar to 10%, 3 tanks of 60 fish each with social disruption; T(high): CV(w) similar to 20%, 3 tanks of 60 fish each, without social disruption). T(low) and T(high) groups were studied over P2, and an additional 27-day period under identical conditions (P3). The grading protocol used and/or time modified the social structure when comparing P1 and P2. Thereafter, during P2 and P3, no difference could be observed in growth performances, feed demand, or physiological variables between T(low) and T(high) groups. Feeding rhythms and social structures were similar in both groups. In conclusion, such grading practice only transiently modifies feed demand behaviour and social structure built around the self-feeder, without further improvement in individual growth performances in sea bass.