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International audience; In the northern Humboldt Current system (NHCS), the Peruvian anchovy (Engraulis ringens) constitutes the bulk of landings and has a significant socioeconomic contribution. Understanding the impact of environment on the early-life stages of anchovy and further population dynamics remains challenging. Climate variability at a variety of scales modulates currents velocity, temperature and food availability, impacting early-life stages drift, growth and survival. In order to investigate these impacts, we developed Ichthyop-DEB, an individual-based model including larval retention processes and a Dynamic Energy Budget (DEB) bioenergetic module for larval growth. First, we assessed the effect of hydrodynamic simulations horizontal resolution on simulated larval retention patterns using a recruitment age-criterion of 30 days. Then, we evaluated the impact of the following biological processes on simulated larval recruitment patterns: (i) a minimum size-criterion (2 cm), as opposed to a minimum age-criterion (30 days), to be considered as recruited, (ii) the upper larval thermal limit tolerance of the species, for which lab experiments are lacking, and (iii) a constant larval mortality rate. We found that using different resolutions of the hydrodynamic model (10 and 2 km) led to similar simulated larval retention patterns. Retention was highest when spawning occurred in the superficial layer (0–15 m) in austral winter and in the deepest considered layer (30–45 m) in summer. Coupling with the DEB model produced contrasted growth patterns on the continental shelf with a strong month-latitude interaction. Larval recruitment was strongest from 6° to 10° S in austral summer, largely contributing to the average seasonal pattern. Depending on the temperature correction function tested with the bioenergetic module, simulated larval recruitment could also be strong in the northernmost zone (2°–4°S), an area not known for abundant anchovy populations, which suggests a possible thermal growth limitation. Finally, sensitivity tests performed on larval growth limitation by food suggested a deficiency in food supply in the southernmost zone (18°–20°S).

International audience; Identifying and protecting essential fish habitats like spawning grounds requires an accurate knowledge of fish spatio-temporal distribution. Commercial declarations coupled with Vessel Monitoring System provide fine scale information on the full year to map fish distribution and identify essential habitats. We developed an integrated framework to infer fish spatial distribution on a monthly time step by combining scientific and commercial data while explicitly considering the preferential sampling of fisher towards areas of higher biomass. We developed a method to identify areas of persistent aggregation of biomass during the spawning season and interpret these as spawning areas. The model is applied to infer maps of relative biomass for three species (sole, whiting and squids) in the Bay of Biscay on a monthly time step over a 9 year period. Integrating several fleets in inference provides a good coverage of the area and improves model predictions. The preferential sampling parameters give insights into the temporal dynamics of the targeting behavior of the different fleets. Last, persistent aggregation areas reveal consistent with the available literature on spawning grounds, highlighting the potential of our approach to identify reproduction areas.

Adaptive fishery responses to climate-induced changes in marine fish populations may lead to fishery maladaptation. Using a stylised bio-economic model of the global fishery, we demonstrate the importance of adaptive management regimes. We show how the losses resulting from poor access regulation increase in a fishery system negatively impacted by environmental change, and demonstrate the proportional benefits provided by management strategies that control the levels and allocation of fishing effort. Indeed, under poor to nonexistent access regulation, highly adaptive actors can generate significant bio-economic losses. This might lead to foregone benefits and cascading economic and ecological losses, whereas well-designed adaptive management regimes may enable making the most of the best, and the least of the worst, climate-induced outcomes for fisheries. These findings emphasize the need for integrated assessment approaches to the impacts of climate change on fisheries, that should incorporate not only ecological responses but also the industry and management responses.

Though fisheries have intensively used drifting fish aggregating devices (DFADs) over the last three decades to facilitate their catch of tropical tunas, assessing the consequences of the presence of DFADs at sea on tuna behaviour and biology is a challenge. The use of DFADs has resulted in a major increase in the number of floating objects, which are spatially heterogeneous at sea. To date, no scientific consensus exists regarding the effects of DFADs on the large-scale movements and behaviour of tuna, mainly due to the difficulty of disentangling the respective roles of DFADs and environmental factors. Some biological indices show that tuna condition is lower when associated to a floating object than in a free-swimming school. It is not possible, however, to elucidate whether this is the cause or result of the association, or if it affects the fitness of individuals in the long term. Further scientific progress would require (i) the collection of time series of indicators to monitor habitat change, individual behaviour, individual fitness and population dynamics, and (ii) experimental studies to identify the underlying behavioural and biological processes involved the associative behaviour. The extent of the modification of the surface habitat by the massive deployment of DFADs and the current uncertainty of the possible long-term consequences on the individual fitness and dynamics of tuna populations argue for the need for increased awareness of this issue by Regional Fisheries Management Organisations regulating tuna fishing.

International audience; Expanding worldwide aquaculture has greatly increased greenhouse gas emissions; however, the underlying microbial mechanisms are poorly understood. In particular, the role of ferric iron [Fe(III)] (hydro) oxides in carbon mineralization in aquaculture pond sediments remains unclear. Here, we studied the rates of microbial Fe(III) reduction, sulfate reduction, methanogenesis, and carbon mineralization in aquaculture shrimp (Litopenaeus vannamei) ponds of various salinities before, during, and after shrimp farming in subtropical estuaries in southeast China. Sediment samples (0–10 cm) were collected to investigate the content of iron species, characteristics of organic matter, and abundance of Geobacter, a proxy of iron reducers. Overall, Fe(III) reduction (46.1% ± 19.1%) dominated carbon mineralization, followed by sulfate reduction (39.6% ± 16.8%) and methanogenesis (1.5% ± 1.1%). Microbial Fe(III) reduction contributed more to carbon mineralization during farming than before and after farming. This enhancement in Fe(III) reduction is attributed to a significant increase in Fe(III) content during farming. Additionally, the contributions of microbial Fe(III) reduction to carbon mineralization were lower in the high-salinity ponds than in the low-salinity ponds due to the suppression of sulfate reduction, abiotic Fe(III) reduction by sulfides, and lower oxidation-reduction potential. Our findings demonstrate that microbial Fe(III) reduction plays a significant role in carbon mineralization in aquaculture pond sediments. Future carbon flux prediction models of aquaculture pond systems should fully integrate microbial Fe(III) reduction.

International audience; To fulfil fisheries management objectives that often include implementing the precautionary and ecosystem-based approaches, multispecies fisheries data need to be analysed. Amongst the different methods dealing with these multidimensional data, self-organizing maps (SOMs) remain rarely used, although they are highly flexible in data input and offer visualization possibilities particularly suited to summarize complex datasets. Here, we propose to combine SOMs with a clustering approach to break down data complexity and produce simple geographic maps showing catch hotspots, which can indicate sensitive zones in terms of fishery management. To promote this approach, we tested it first on simulated datasets and then on the open-access ICCAT commercial catch database of the tropical tuna fisheries of the Atlantic Ocean. We aimed to detect drifting fish aggregating devices (dFADs) catch hotspots of juveniles of two tuna species, bigeye and yellowfin tunas and of the silky shark, a commonly bycaught vulnerable shark species, in tropical tuna purse seine fisheries. Simulations on datasets increasing in complexity (in number, geographic and duration extent of the hotspots and number of species in the analysis) informed us about the method's sensitivity and limits. Our findings showed that, in the context of multi-specific fisheries, the detection of the hotspot is dependent on a certain level of catch within the hotspot and that adding species to the analysis tended to mask small and short-duration hotspots. Applied to tropical tuna fisheries' data, the method confirmed the empirical knowledge on which first time-area closures were based and provided scientifical support. All in all, the visual support provided by the method, its interpretability and its potential transferability to other fisheries' systems constitute its main strengths and imply a possible implementation in management decisions; specifically, as a tool to reach agreement between stakeholders in the definition of regulated areas for protecting juveniles of tunas and vulnerable associated species to dFAD practices.

The COVID-19 has led to the closure of commercial catering, restrictions on imports and fishing. Besides a restrictive and anxiety-provoking context, consumption habits have likely been challenged. Fresh fishery and aquaculture products (FAP) are largely consumed at home and are very sensitive to logistical constraints (short shelf life). Quantitative data on household home purchases in metropolitan France from 2017 to 2021 were used. It seems consumption of fresh FAPs has not truly adapted to the national fish production in disregard of import restrictions and available surpluses. While the consumption of fresh shellfish at home did not change significantly in 2020, salmon and cod are still substantially preferred by French consumers at home, although their French production is almost non-existent. On the contrary, locally produced fish species remain little consumed at home. The abundant supply of fresh salmon initially destined for other markets has consolidated the dominant position of this species in the French home consumption market. Initiated by supermarkets and hypermarkets and followed by consumers, the trend to purchase pre-packaged fresh fish has been largely amplified by the pandemic and seems to persist over time., La crise sanitaire a provoqué la fermeture généralisée de la restauration commerciale, des restrictions sur les importations ainsi que sur l’exercice de la pêche. Additionnées à un contexte restrictif et anxiogène, les habitudes de consommation ont très probablement été remises en question. Les produits de la pêche et de l’aquaculture (PPA) frais sont largement consommés à domicile et sont très sensibles aux contraintes logistiques (conservation courte). Des données quantitatives sur les achats à domicile des ménages en France métropolitaine de 2017 à 2021 ont été utilisées. Il semble que la consommation de PPA frais ne se soit pas vraiment adaptée à la production nationale de poissons au mépris des restrictions à l’importation et des excédents disponibles. Alors que la consommation de coquillages frais à domicile n’a pas évolué de manière significative en 2020, le saumon et le cabillaud restent toujours largement privilégiés par les consommateurs français à domicile, bien que leur production française soit quasi inexistante. Au contraire, les espèces de poisons produites localement restent peu consommées à domicile. L’offre abondante de saumon frais, initialement destiné à d’autres marchés, a permis de consolider la position dominante de cette espèce sur le marché français de la consommation à domicile. Initiée par les supermarchés et hypermarchés et suivie par les consommateurs, la tendance à l’achat de poisson frais préemballé a été largement amplifiée par la pandémie et semble persister dans le temps.

International audience

Le présent document décrit l’utilisation des modèles linéaires généralisés (GLM) pour la création d’indices d’abondance du stock de Thiof (Epinephelus aeneus / White Grouper) Senegalo / Mauritanien. Les modèles GLM permettent de prendre en compte les variations de protocole d’échantillonnage dans l’observation des captures des flottilles de pêche concernées. Les données utilisées proviennent, d’une part des campagnes scientifique démersales réalisées en Mauritanie depuis les années 1980, et d’autre part des données de captures et d’effort des pêcheries artisanales maritimes collectées en Mauritanie. French (2022-07-10)

International audience; Mauritania is characterized by fast-growing fisheries that have developed over the past several decades from low levels of fishing to intense fishing and have led to severe decreases in biomass and severe signs of overexploitation. To ensure sustainable fisheries, a primary goal of science-based fisheries policy is to provide an adequate conservation status of marine habitats that are directly, or indirectly, fundamental for the lifecycle of fish populations of commercial interest. The National Park of Banc d'Arguin has been recognized for its nursery and fish biomass export functions. In this paper, we present the economic value of the fish provisioning service of marine coastal ecosystems of the protected area. We estimated the added value of artisanal fisheries, the spatial distribution of fishing activities, the contribution of the Park to the Mauritanian fisheries and the heritage value of artisanal fisheries. Overall, the average added value for artisanal fisheries is about 43 million MRU (1 million euros) over the period 2006-2017. It mainly benefits to the shipowners , which generates inequalities and threatens the livelihoods of the Imraguen. The spatial distribution of fishing activities and associated revenues shows high variability throughout the years, the seasons and the geographic areas, and reveals the high adaptability of Imraguen fishers. Fishing grounds are mostly located close to the shore, associated with seagrass beds, confirming the service of fish provisioning rendered by this ecosystem. Furthermore, the high productivity of seagrass beds contributes to the spill-over of biomass. The contribution of the Park to fishing activities that occur within the Mauritanian Exclusive Economic Zone is estimated to 15%, representing an added value creation of 3.2 billion MRU (71 million euros). The heritage value of the fisheries is assessed, through fishers' willingness to accept to stop their fishing activities, at 17.5 million MRU (0.4 million euros). Thus, this paper highlights the necessity of incorporating an ecosystem-based approach along with fishers' knowledge and adaptability into future conservation plan of the National Park of Banc d'Arguin and fisheries management at the local, national and regional scale.

International audience; The pikeperch is a freshwater/brackish water fish species with growing interest for European aquaculture. Wild populations show signs of decline in many areas of the species natural range due to human activities. The comparative evaluation of genetic status in wild and domesticated populations is extremely useful for the future establishment of genetic breeding programs. The main objective of the present study was to assess and compare the genetic variability of 13 domesticated populations from commercial farms and 8 wild populations, developing an efficient microsatellite multiplex tool for genotyping. Partial cytochrome b gene sequences were also used to infer phylogeographic relationships. Results show that on average, the domesticated populations do not exhibit significantly lower levels of genetic diversity compared to the wild ones and do not suffer from inbreeding. Nuclear data provide evidence that pikeperch populations in Europe belong to at least two genetically differentiated groups: the first one is predominantly present in Northern Europe and around the Baltic Sea, while the second one comprises populations from Central Europe. In this second group, Hungarian origin populations constitute a differentiated stock that needs special consideration. Aquaculture broodstocks analyzed appear to contain fish of a single origin with only a few exceptions.

International audience; Satellite-linked buoys used by tropical tuna purse-seine vessels on drifting fish aggregating devices (DFADs) provide a continuous stream of information on both the ocean characteristics and the presence and size of fish aggregations associated with DFADs, enabling the study of pelagic communities. This unprecedented amount of data is characterized by ocean-scale coverage with high spatial and temporal resolutions, but also by different data formats and specifications depending on buoy model and brand, as well as on the type of data exchange agreements into play. Their use for scientific and management purposes is therefore critically dependent on the abilities of algorithms to process heterogeneous data formats and resolutions. This paper proposes a unified set of algorithms for processing the buoys location data used by the two major purse seine fleets operating in the Atlantic and Indian oceans. Three main issues that need to be addressed prior to the exploitation of the data are identified (structural errors, data records on land and on-board vessels) and five specific filtering criteria are proposed to improve the data cleaning process and, hence, quality. Different filtering procedures are also compared, and their advantages and limitations are discussed.

The surmullet Mullus surmuletus Linnaeus, 1758 is one of the main target and high valuespecies for small coastal fisheries in the North-Western Mediterranean. Morphometric andreproduction indices of surmullet were determined in fisheries regulated and non-regulatedzones neighbouring the Port-Cros National Park (South-Eastern France) in autumn 2019 andspring 2020. Total length of individuals ranged between 12 and 32 cm, with a mode (?)between 17 and 23 cm. Significantly larger individuals were measured in the regulated fishingzones than in non-regulated ones, and in autumn rather than in spring. Females dominated inall zones and seasons, particularly in size classes > 24 cm in spring. Higher gonado-somaticindex and more advanced gonadal development stages were observed in both sexes in springthan in autumn. Higher percentages of individuals with mature gonads and high gonado-somatic index were found in the fisheries regulated zone, engendering a higher reproductivepotential. These results highlighted the importance of fisheries management with regard to thelife-history traits of targeted fish species., Le rouget de roche Mullus surmuletus est l'une des principales espèces cibles etcommerciales des pêcheries côtières artisanales de la Méditerranée nord-occidentale. Lamorphométrie et les indices de reproduction du rouget ont été déterminés dans les zones depêche réglementées et non réglementées autour du Parc National de Port-Cros (Sud-Est de laFrance) à l'automne 2019 et au printemps 2020. La longueur totale des individus variait entre12 et 32 cm, avec un mode entre 17 et 23 cm. Des individus significativement plus grands ontété mesurés dans la zone de pêche réglementée comparativement aux zones non réglementées,et en automne par rapport au printemps. Les femelles dominaient dans toutes les zones etsaisons, en particulier dans les classes de taille > 24 cm au printemps. Un indice gonado-somatique plus élevé et des stades de développement gonadiques plus avancés au printempsqu’en automne ont été observés chez les deux sexes. Des pourcentages plus élevés d'individusavec des gonades matures et un indice gonado-somatique élevé ont été trouvés dans la zone depêche réglementée, induisant un plus fort potentiel reproducteur. Ces résultats mettent enévidence l'importance de la gestion des pêches sur les traits d'histoire de vie des espèces depoissons ciblés.

Maldivians have sustainably been exploiting tuna using hook and line in the Indian Ocean for over a millennium, with 20% of the total Indian Ocean tuna catches currently landed in the Maldives. After four decades using on average 55 anchored fish aggregating devices (AFADs) spread over the entire archipelago, this thesis aims to improve our knowledge on the fishery ecology of tuna within the Maldivian AFAD array in order to better understand the drivers of the sustainability of the fishery for the coming years. The ecology of tuna around these AFADs was studied by collecting local ecological knowledge from 54 pole and line fishers and by acoustically tagging 65 skipjack and 57 yellowfin tuna within an instrumented 21-AFAD array. Most fishers consider that slight currents, suitable sea temperature, prey and attractants enhance the aggregations while strong currents, high sea temperatures and stormy conditions make tuna leave AFADs. They also consider that tuna tend to stay associated with AFADs 3 to 6 days, which is comparable to results from acoustic tagging (from 2 to 5.5 days on average). Acoustic tagging showed that tuna do not have a specific preference in the direction of movement, and very few fish moved from one FAD to another. Therefore, the 55 AFADs in the Maldives do not act like a network but appear to be relatively independent. The Maldives FAD network can be considered as a case study to examine the pros and cons of sparse FAD networks as supports for fisheries, while minimizing potential negative impacts. More research on the ecological, social and economic aspects of the pole and line fishery must be conducted to support the Maldives in their science-based management.Keywords: Anchored Fish Aggregating Device, Tropical tunas, Pole and Line, Maldives, Local Ecological Knowledge, Residence Time., Les Maldiviens exploitent durablement le thon dans l'océan Indien depuis plus d'un millénaire, avec 20% des captures totales de thon de l'océan Indien actuellement débarquées aux Maldives. Après quatre décennies d'utilisation d'une moyenne de 55 dispositifs de concentration de poissons ancrés (DCPA-) répartis sur l'ensemble de l'archipel, cette thèse vise à améliorer nos connaissances sur l'écologie de la pêche au thon au sein du réseau de DCP des Maldives afin de mieux comprendre les moteurs de la durabilité de la pêche pour les années à venir. L'écologie du thon autour de ces DCP a été étudiée en recueillant les connaissances écologiques locales de 54 pêcheurs à la canne et en marquant acoustiquement 65 listaos et 57 albacores dans un réseau de 21 DCP instrumentés. La plupart des pêcheurs considèrent que des courants faibles, une température de la mer adaptée, des proies et des attractifs favorisent les agrégations tandis que des courants forts, des températures de la mer élevées et des conditions orageuses font que les thons quittent les DCP. Ils considèrent également que les thons ont tendance à rester associés aux DCP de 3 à 6 jours, ce qui est comparable aux résultats du marquage acoustique (de 2 à 5,5 jours en moyenne). Le marquage acoustique a montré que les thons n'ont pas de préférence spécifique dans la direction du mouvement, et que très peu de poissons se déplacent d'un DCP à l'autre. Par conséquent, les 55 DCP des Maldives ne fonctionnent pas comme un réseau mais semblent être relativement indépendants. Le réseau de DCP des Maldives peut être considéré comme une étude de cas pour examiner les avantages et les inconvénients des réseaux de DCP peu denses comme supports pour les pêcheries, tout en minimisant les impacts négatifs potentiels. Des recherches supplémentaires sur les aspects écologiques, sociaux et économiques de la pêche à la canne doivent être menées pour soutenir les Maldives dans leur gestion basée sur la scie nce.Mots clés: dispositif de concentration de poissons ancré, thons tropicaux, canne et ligne, Maldives, connaissances écologiques locales, temps de résidence

12 pages, 6 figures, supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2112660118/-/DCSupplemental.-- Data Availability: RNA-Seq and .xls tables data have been deposited in a publicly accessible database: SEXTAN (https://sextant.ifremer.fr/record/5cb1485f-385e-46e9-9cc1-4b4d77802183/). All other study data are included in the article and/or supporting information, In most animals, sex determination occurs at conception, when sex chromosomes are segregated following Mendelian laws. However, in multiple reptiles and fishes, this genetic sex can be overridden by external factors after fertilization or birth. In some species, the genetic sex may also be governed by multiple genes, further limiting our understanding of sex determination in such species. We used the European sea bass (Dicentrarchus labrax) as a model and combined genomic (using a single nucleotide polymorphism chip) and transcriptomic (RNA-Sequencing) approaches to thoroughly depict this polygenic sex determination system and its interaction with temperature. We estimated genetic sex tendency (eGST), defined as the estimated genetic liability to become a given sex under a liability threshold model for sex determination, which accurately predicts the future phenotypic sex. We found evidence that energetic pathways, concerning the regulation of lipids and glucose, are involved in sex determination and could explain why females tend to exhibit higher energy levels and improved growth compared to males. Besides, early exposure to high-temperature up-regulated sox3, followed by sox9a in individuals with intermediate eGST, but not in individuals showing highly female-biased eGST, providing the most parsimonious explanation for temperature-induced masculinization. This gonadal state was maintained likely by DNA methylation and the up-regulation of several genes involved in histone modifications, including jmjd1c. Overall, we describe a sex determination system resulting from continuous genetic and environmental influences in an animal. Our results provide significant progress in our understanding of the mechanisms underlying temperature-induced masculinization in fish, The study was supported by the European Maritime and Fisheries Fund (3S, Seabass Sex and Stress, Grant No. 4320175237) allocated to B.G. Production of the fish benefited from AQUAEXCEL2020 Transnational access grant “Transsexbass” to F.P. and M.V. Research at the F.P. laboratory was supported by Spanish Ministry of Science Grant No. PID2019-108888RB-I00., With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

In European sea bass (Dicentrarchus labrax), as in many other fish species, temperature is known to influence the sex of individuals, with more males produced at relatively high temperatures. It is however unclear to what extent growth or stress are involved in such a process, since temperature is known to influence both growth rate and cortisol production. Here, we designed an experiment aiming at reducing stress and affecting early growth rate. We exposed larvae and juveniles originating from both captive and wild parents to three different treatments: low stocking density, food supplemented with tryptophan and a control. Low stocking density and tryptophan treatment respectively increased and decreased early growth rate. Each treatment influenced the stress response depending on the developmental stage, although no clear pattern regarding the whole-body cortisol concentration was found. During sex differentiation, fish in the low-density treatment exhibited lower expression of gr1, gr2, mr, and crf in the hypothalamus when compared to the control group. Fish fed tryptophan displayed lower crf in the hypothalamus and higher level of serotonin in the telencephalon compared to controls. Overall, fish kept at low density produced significantly more females than both control and fish fed tryptophan. Parents that have been selected for growth for three generations also produced significantly more females than parents of wild origin. Our findings did not allow to detect a clear effect of stress at the group level and rather point out a key role of early sexually dimorphic growth rate in sex determination.

Fisheries management is an important strategy for ensuring sustainable use of resources. However, in West Africa, in the absence of quality data for many stocks and effective stock assessment models, the cases where this has been truly successful are notable for their rarity. In West Africa, small pelagic fish are of great socio-economic importance, as well as good indicators of fish stressors. Here, historical data (2004–2019) of five small pelagic species (Sardina pilchardus, Ethmalosa fimbriata, Trachurus trecae, Scomber colias and Mugil cephalus) were collected in Senegalese waters. The B/BMSY results showed stocks to be collapsed (B/BMSY = 0.13 and 0.1 for M. cephalus and S. pilchardus, respectively) and heavily overfished (B/BMSY = 0.24; E. fimbriata). Only S. colias and T. trecae stock were considered to be in good condition (B/BMSY = 1.7 and 1.4 respectively). The Lc/Lc_opt ratio was ≤ 1 for E. fimbriata and M. cephalus, suggesting that the individuals caught for these species were too small. To reverse these bad stock statuses, catching individuals at Lc_opt, 25, 21, 43 and 18 cm for S. colias, E. fimbriata, M. cephalus and S. pilchardus, respectively should be a natural guarantee against recruitment failure and allow individuals to ensure the long-term survival of populations, in a context of data poor fisheries. In conclusion, this study shows that, despite limitations, the LBB model can provides indicators of stock status for species to encourage management measures, especially in data poor countries. It is hoped that these results can help to better assess many stocks currently considered too data poor to be assessed or at least encourage data collection effort on stocks discerned as in bad or critical status.

Electronic monitoring systems (EMS) have increasingly been used as an alternative technology to complement onboard observer programs and improve the management of tuna fisheries. EMS was installed on French purse seiners in 2014 in the frame of the OCUP program and pilot studies have shown that the system allows in-depth monitoring of fishing activities by providing information on catch composition and handling on deck and below deck. In this study, we further explore the potential of EMS for monitoring the hauling process of tropical tuna purse seiners' catch from the net to the deck. Using information collected during brailing (number of brailers, timing, fullness) on board 5 vessels of the Indian Ocean during 2018-2019, we evaluate the suitability of EMS as a tool to describe the main trends in brailing operations over 50 fishing sets. Our results indicate a large variability in brailer fullness among fishing sets and a relatively fast loading of the catch onto the deck with brailing operations generally consisting of 4 to 5 brailers transferred on board in less than 15 minutes. Results confirm the potential of EMS for collecting complementary data to monitor brailing operations of tropical tuna purse seiners.

International audience

International audience

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International audience

Aquaculture Europe, Oceans opportunity, 4-7 October 2021, Madeira, Portugal.-- 2 pages, 1 figure, European sea bass (Dicentrarchus labrax) is an important European aquaculture species. Females, performing better than males with later maturation and larger size, are preferred. Unfortunately, in aquaculture conditions, the sex-ratio is typically biased towards males. Thus, deciphering the sex determinism system and finding routes for controlling the sexratio of this species has been a long-lasting challenge to support sea bass production and selective breeding programmes. A polygenic threshold sex determination system was demonstrated (Vandeputte et al. 2007), where the genetic sex tendency is influenced by larval rearing temperature to determine the phenotypic sex (Piferrer et al, 2005). In this study, we applied two thermal treatments during early larval stage, a low temperature protocol (16°C, LT), known to favour more balanced sex-ratios, and a high temperature masculinizing protocol (21°C, HT). We used genome-wide SNP genotypes to estimate the genetic parameters and genotype-by-temperature interaction of sex tendency in European sea bass, This work was partially supported by the 3S - Seabass Sex and Stress project (n° 4320175237) funded by the French Government and the European Union (EMFF, European Maritime and Fisheries Fund) at the “Appels à projets Innovants” managed by the France Agrimer Office, and the European Union’s 7th Framework Programme under Grant Agreement 652831 (AQUAEXCEL2020, Transnational Access project AE040073)

Size-selective mortality due to harvesting is a threat to numerous exploited species, but how it affects the ecosystem remains largely unexplored. Here, we used a pond mesocosm experiment to assess how evolutionary responses to opposite size-selective mortality interacted with the environment (fish density and light intensity used as a proxy of resource availability) to modulate fish populations, prey community composition and ecosystem functions. We used medaka ( Oryzias latipes ) previously selected over 10 generations for small size (harvest-like selection; small-breeder line) or large size (large-breeder line), which displayed slow somatic growth and early maturity or fast somatic growth and late maturity, respectively. Large-breeder medaka produced more juveniles, which seemed to grow faster than small-breeder ones but only under high fish density. Additionally, large-breeder medaka had an increased impact on some benthic prey, suggesting expanded diet breadth and/or enhanced foraging abilities. As a consequence, increased light stimulated benthic algae biomass only in presence of large-breeder medaka, which were presumably better at controlling benthic grazers. Aggregated effect sizes at the community and ecosystem levels revealed that the ecological effects of medaka evolution were of similar magnitude to those induced by the environment and fish introduction. These findings indicate the important environmental dependency of evolutionary response to opposite size-selective mortality on higher levels of biological organizations.

International audience; The high economic value of fisheries was historically associated to commercial teleost fishes. Since the 1970s, despite some elasmobranchs becoming an important target or a bycatch, relatively little research has been carried out on this group because of their low economic value. Due to their specific life history characteristics, sharks and rays are particularly vulnerable to overexploitation, taking several decades to recover after reaching an overexploitation status. In Portugal elasmobranch fishery results mainly from targeted longlining and bycatch from different fishing gears. During the last decade, the Total Allowable Catches (TACs) of rays have been decreasing, the European Union (EU) banned the capture of some ray species, the Portuguese government implemented both a closed season and a minimum landing size for some rays, and the EU prohibited target fishing for sharks. All these measures may have been highly responsible for the national and local landings reduction. Official landings from the last decade were analyzed, the landed species conservation status was consulted, and structured interviews using a questionnaire were conducted in the most important fishing port in the Portuguese mainland, the port of Sesimbra. Results led us to conclude that fishers’ answers and landings data did not match. It also revealed a lack of awareness by fishers about the state of shark and ray populations, and about some aspects of their biology and ecology, like reproduction season and method. The present study highlights the need to fill in this existing gap in knowledge through the transfer of scientific knowledge and sharing of management responsibilities. Also, we aimed to demonstrate the necessity for awareness and education activities within fishing communities, an essential step to elasmobranch conservation.

This report presents new stock assessments for the rock lobster (Jasus paulensis) fishery of the Saint Paul and Amsterdam islands with data up to the last fishing campaign of 2020/21. These new assessments are based on statistical catch at age models using all available data except tagging program data.Stock status trajectories for both stocks start from a period of unsustainable fishing in the 1980s and recovered in the 1990s. The assessment results indicate that exploitable biomass in 2020 is likely to be well above BMSY, biomass status (B/BMSY) are 1.09 (0.86 - 1.50) and 2.12 (1.66 – 2.92) for Saint Paul and Amsterdam stocks respectively, and that fishing mortality is well below FMSY. These estimates are consistent with the results of preliminary assessment from biomass dynamic models.The short-term projection scenarios that were tested show that current catch levels are compatible with the sustainability of the rock lobster stocks.

International audience; The 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.

The lack of effective governance is a major concern in small-scale fisheries. The implementation of governance that encompasses the three pillars of sustainability (social, economic, and ecological) is still a worldwide challenge. We examined nine stalked barnacle fisheries ( Pollicipes pollicipes ) across Southwest Europe to better understand the relationship between governance elements and sustainability. Our results show that nested spatial scales of management, the access structure, co-management, and fisher’s participation in monitoring and surveillance promote sustainability. However, it is not the mere presence of these elements but their level of implementation that drives sustainability. Efforts should be placed in the accomplishment of a minimum combination of local scales of management, access rights through individual quotas, instructive-consultative co-management and functional participation. Surpassing this threshold in future governance structures will start to adequately promote social, economic and ecologically sustainability in small-scale fisheries. Ministerio de Economía y Competitividad | Ref. PCIN-2016-120 Ministerio de Ciencia, Innovación y Universidades | Ref. FPU2016-04258 European Research Council | Ref. n. 8679812 Fundação para a Ciência e Tecnologia | Ref. UID / MAR / 04292/2019 Fundação para a Ciência e Tecnologia | Ref. UIDP / 50017/2020? Fundação para a Ciência e Tecnologia | Ref. UIDB / 50017/2020

International audience; Recent improvements in taxonomy consider multiple operational criteria. Integrative taxonomy provides a methodological framework merging these multisource approaches. Bumblebees are considered as a uniform group where their taxonomy remains one of the most difficult. Here, we investigate the taxonomic statuses inside a monophyletic group including six taxa (B. inexspectatus, B. mlokosievitzii, B. ruderarius, B. sylvarum, B. velox and B. veteranus)in the most diverse subgenus of bumblebees: Thoracobombus. We used an integrative approach based on mitochondrial and nuclear genetic markers and eco-chemical traits commonly used in bumblebee taxonomy. For all species, our study shows a clear differentiation in DNA and eco-chemical traits. However, we conserve the subspecies status of B. ruderarius simulatilis and B. sylvarum daghestanicus from the east of Turkey and Iran according to their degree of genetic and eco-chemical differentiation

International audience; Survival success of early life stages of fish is regulated by density-dependent effects, but the limiting factors explaining these effects have not been well identified. In coastal habitats, juveniles of many fish species occur in high concentrations and possibly compete for food resources. This study compared the ratio of food consumption to benthic prey production to test whether food availability is a major factor defining the carrying capacity of fish nurseries. We developed a method to quantify the exploitation efficiency (also called ecotrophic efficiency) of the juvenile fish feeding on benthic prey, expressed as a ratio of food consumption to food production. This method includes many sources of uncertainty and a key parameter of prey accessibility. Applied to the case study of the Bay of Vilaine (north Bay of Biscay), results suggest food limitation for juvenile fish. The generic nature of this method supports its wide application in various nursery habitats. As food limitation is a density-dependent process having a dampening effect on recruitment variability, examining its occurrence over time and space will improve our comprehension of nursery-dependent fish dynamics

Effective sustainable management of marine fisheries requires that assessed management units (that is, fish stocks) correspond to biological populations. This issue has long been discussed in the context of Atlantic bluefin tuna (ABFT, Thunnus thynnus) management, which currently considers two unmixed stocks but does not take into account how individuals born in each of the two main spawning grounds (Gulf of Mexico and Mediterranean Sea) mix in feeding aggregations throughout the Atlantic Ocean. Using thousands of genome-wide molecular markers obtained from larvae and young of the year collected at the species’ main spawning grounds, we provide what is, to the best of our knowledge, the first direct genetic evidence for “natal homing” in ABFT. This has facilitated the development of an accurate, cost-effective, and non-invasive tool for tracing the genetic origin of ABFT that allows for the assignment of catches to their population of origin, which is crucial for ensuring that ABFT management is based on biologically meaningful stock units rather than simply on catch location., Sí

International audience; The aim of this study was to identify the main bacterial pathogens affecting tilapia aquaculture in Guatemala during 2018-2019 and evaluate their resistance to the most widely used antibiotics in the aquaculture industry of the area. Fish weighing between 50 and 1,000 g were collected from different production centers. The most frequent external and internal macroscopic signs were recorded for each organism. In addition, bacteriological samples of blood fluid, ulcers and other hemorrhagic areas, anterior kidney, spleen, meninges, liver, and heart were isolated. The isolated pathogenic bacteria were identified at the species level through biochemical tests. Finally, susceptibility was assessed with the following antibiotics oxytetracycline (40 µg), florfenicol (40 µg), enrofloxacin (40 µg), and fosfomycin (40 µg) by the disk diffusion method. The most common clinical signals were skin ulcers, hyperemic areas, body melanization, pale and soft liver, liver vasculitis, and intestinal congestion and bleeding. A total of 16 pathogenic bacteria strains were isolated from tilapia samples. The most frequent genera were Aeromonas (70%: 3 spp), followed by Plesiomonas, Burkholderia, Pseudomonas, Shewanella, and Streptococcus (6%; 1 sp). Isolated bacteria strains showed resistance to oxytetracycline (25%) and fosfomycin (25%) and sensitivity to florfenicol and enrofloxacin. This is the first report related to the most frequent bacterial pathogens and their antimicrobial resistance in tilapia culture in Guatemala.; Este estudio muestra el trabajo realizado durante el año 2018-2019, donde se identificaron los principales patógenos bacterianos que afectan los cultivos de la tilapia en Guatemala, al mismo tiempo se evaluó la resistencia a los antibióticos de mayor uso en la industria acuícola de esta zona. Se recolectaron peces con peso de 50 a 1 000 g, en diversos centros de producción. Por cada organismo se registró la signología macroscópica externa e interna más frecuente, posteriormente se aislaron muestras bacteriológicas de fluido sanguíneo, úlceras y otras áreas hemorrágicas, riñón anterior, bazo, meninges, hígado y corazón. Las bacterias patógenas aisladas fueron identificadas a nivel de especie, a través de pruebas bioquímicas. Finalmente se evaluó la susceptibilidad con los antibióticos: oxitetraciclina (40 µg), florfenicol (40 µg), enrofloxacina (40 µg) y fosfomicina (40 µg) por el método de difusión de disco. Los organismos evidenciaron, en su mayoría, ulceras cutáneas, áreas hiperémicas, melanización corporal, hígado pálido y friable, vasculitis en hígado, congestión y hemorragia intestinal. Se lograron aislar 16 cepas bacterianas patógenas para la tilapia, los géneros más frecuentes fueron: Aeromonas (70 %: 3 spp), seguido por Plesiomonas, Burkholderia, Pseudomonas, Shewanella y Streptococcus (6 %: 1 sp). Se observó que las cepas bacterianas aisladas mostraron resistencia hacia los antibióticos oxitetraciclina (25 %) y fosfomicina (25 %). Todas las cepas bacterianas aisladas evidenciaron sensibilidad a florfenicol y enrofloxacina. La determinación de los patógenos más frecuentes, así como su resistencia antimicrobiana en la industria acuícola, es el primer reporte que se genera para Guatemala.; Este estudo mostra o trabalho realizado durante os anos 2018 e 2019, em que foram identificados os principais patógenos bacterianos que afetam os cultivos da tilápia na Guatemala e, conjuntamente, avaliada a resistência aos antibióticos mais usados na indústria aquícola desta zona. Foram coletados peixes com peso de 50 a 1000g, em diversos centros de produção. Por cada organismo, houve o registro dos sinais macroscópicos externos e internos mais frequente, posteriormente foram isoladas amostras bacteriológicas de: fluxo sanguíneo, úlceras e outras áreas hemorrágicas, rim anterior, baço, meninges, fígado e coração. As bactérias patógenas isoladas foram identificadas por espécie, através de provas bioquímica. Finalmente, a susceptibilidade foi avaliada com os antibióticos: oxitetraciclina (40 µg), florfenicol (40 µg), enrofloxacino (40 µg) e fosfomicina (40 µg) por meio do método de disco-difusão. Os organismos evidenciaram, em sua maioria, úlceras cutâneas, áreas hiperêmicas, melanização corporal, fígado pálido e friável, vasculites no fígado, congestão e hemorragia intestinal. Foi possível o isolamento de 16 cepas bacterianas patógenas para a tilápia, sendo os gêneros mais frequentes: Aeromonas (70 %: 3 spp.), seguido por Plesiomonas, Burkholderia, Pseudomonas, Shewanella e Streptococcus (6 %: 1 sp.). Observou-se que as cepas bacterianas isoladas mostraram resistência com relação aos antibióticos oxitetraciclina (25 %) e fosfomicina (25 %). Todas as cepas bacterianas isoladas mostraram sensibilidade ao florfenicol e ao enrofloxacino. A determinação dos patógenos mais frequentes, assim como sua resistência antimicrobiana na indústria aquícola é o primeiro relatório gerado para a Guatemala.

Feed efficiency (FE) is the amount of body weight gain for a given feed intake. Improving FE through selective breeding is key for sustainable finfish aquaculture but its evaluation at individual level is technically challenging. We therefore investigated whether individual routine metabolic rate (RMR) was a predictor of individual FE in the European sea bass Dicentrarchus labrax, a major species in European mariculture. The European sea bass has three genetically distinct populations across its geographical range, namely Atlantic (AT), West Mediterranean (WM), and East Mediterranean (EM). We compared FE and RMR of fish from these three populations at 18 or 24 °C. We held 200 fish (62 AT, 66 WM, and 72 EM) in individual aquaria and fed them from ad libitum down to fasting. FI was assessed for an ad libitum feeding rate and for a fixed restricted ration (1% of metabolic body weight·day−1, with metabolic body weight = body weight0.8). After being refed 12 wk in a common tank, individual RMR was measured over 36 h by intermittent flow respirometry. There was a significant effect of temperature whereby fish at 18 °C had greater mean FE (P < 0.05) and lower RMR (P < 0.001). There was also a significant effect of population, where AT fish had lower FE (P < 0.05) and greater RMR (P < 0.001) than WM and EM, at both temperatures. Despite these differences in temperature and population means, individual FE and RMR were not significantly correlated (P > 0.05). Therefore, although the results provide evidence of an association between metabolic rate and FE, RMR was not a predictor of individual FE, for reasons that require further investigation.

International audience; In temperate zones, energy reserves of fish are closely related to survival during the first winter of their life. In this study, the genetic and phenotypic background of the accumulation, mobilization and utilization of energy reserves was investigated in Amur mirror carp. To achieve this, the role of traits related to energy reserves on fish performance during the first winter and further periods of rearing was investigated. The experimental stock was established by four full-factorial matings of 5 dams and 10 sires to generate up to 200 full-sibling families. The offspring were sampled before and after the first winter rearing period. Seasonal variation in direct and indirect measures of energy status was examined using Fulton's condition factor (FC), hepato-somatic index (HSI), visceral index (VSI_NO), glycogen, fat and protein in hepatopancreas (HP) and muscle fat content. Other performance traits were also recorded (weight, resistance to koi herpesvirus disease). All traits related to energy reserves, except HP protein, were significantly lower after the first winter. Overall, HP glycogen and fat from muscle, HP and viscera were mobilized during winter. However, genetic correlations between same traits recorded in autumn and spring were lower than 0.8 for most of the traits, implying that not all families responded to overwintering in a similar manner. Heritability also differed before and after the first winter. Before the first winter, all traits had low to medium heritability (0.05-0.35), but after the winter the same traits were moderately or highly heritable (0.22-0.58). Interestingly, HP glycogen traits, unlike HP fat and HP protein, and HSI recorded in yearlings were positively genetically correlated with survival during the third growing season (rg = 0.49-0.72). This study provides the first evidence of a genetically based strategy for energy mobilization related to overwintering of common carp. Measuring of FC and HSI could be used to monitor the energy status of common carp and to provide a supplementary tool for management of carp stocks.

International audience

The European sea bass (Dicentrarchus labrax) exhibits female-biased sexual size dimorphism (SSD) early in development. New tagging techniques provide the opportunity to monitor individual sex-related growth during the post-larval and juvenile stages. We produced an experimental population through artificial fertilization and followed a rearing-temperature protocol (~16°C from hatching to 112 days post-hatching, dph; ~20°C from 117 to 358 dph) targeting a roughly balanced sex ratio. The fish were tagged with microchips between 61 and 96 dph in five tagging trials of 50 fish each; individual standard length (SL) was recorded through repeated biometric measurements performed between 83 to 110 dph via image analyses. Body weight (BW) was modelled using the traits measured on the digital pictures (i.e. area, perimeter and volume). At 117 dph, the fish were tagged with microtags and regularly measured for SL and BW until 335 dph. The experiment ended at 358 dph with the sexing of the fish. The sex-ratio at the end of the experiment was significantly in favor of the females (65.6% vs. 34.4%). The females were significantly longer and heavier than the males from 103 dph (~30 mm SL, ~0.44 g BW) to 165 dph, but the modeling of the growth curves suggests that differences in size already existed at 83 dph. A significant difference in the daily growth coefficient (DGC) was observed only between 96 and 103 dph, suggesting a physiological or biological change occurring during this period. The female-biased SSD pattern in European sea bass is thus strongly influenced by very early growth differences between sexes, as already shown in previous studies, and in any case long before gonadal sex differentiation has been started, and thus probably before sex has been determined. This leads to the hypothesis that early growth might be a cause rather than a consequence of sex differentiation in sea bass.

The demand for fish products in Black Sea riparian countries has been intensively growing annually by 4% since 2000. This demand was predominantly covered by importation and/or capture fisheries. T...

The aim of this article is to characterize the individual and collective initiatives implemented by Senegalese artisanal fishermen to confront the crisis (ecological and economic). Such initiatives are organized around new – “legal” or “illegal” – “political” and “technical” dynamics, such as migrant fishing, the targeting of new resources, mixed fishing techniques, and even pickup boats. We first characterize these initiatives, then we analyze their scope in the context of an acute crisis and the future in the context of sustainable management of fish stocks and the hardening of national and regional legislation (at the ECOWAS and SRFC levels)., L’objectif de l’article est de caractériser les initiatives individuelles et collectives mises en œuvre par les pêcheurs artisans sénégalais pour faire face à la crise (écologique et économique). De telles initiatives s’organisent autour de dynamiques nouvelles « politiques » et « techniques », « légales » ou « illégales » à l’exemple de la pêche migrante, le ciblage de nouvelles ressources, la mixité des techniques de pêche, ou encore les bateaux ramasseurs. Il s’agit ici de caractériser d’abord ces initiatives, d’en analyser ensuite la portée en contexte de crise aiguë et le devenir en contexte de gestion durable des stocks halieutiques et de durcissement des législations nationales et régionales (à l’échelle de la Communauté économique des États de l’Afrique de l’Ouest (CEDEAO) et de la Commission sous-régionale des pêches (CSRP)).

International audience; The reformed Common Fisheries Policy of the EU, in force since 2014, stipulates that overfishing by the fleets of its member states has to end latest in the year 2020. This study examines exploitation and status of 119 stocks fished by 20 countries in the Northeast Atlantic. In the year 2018, about 40% of the stocks were still subject to overfishing (F > Fmsy), about 34% of the stocks were outside safe biological limits (B < Bpa) and about 68% of the stocks were too small to produce maximum sustainable yields (B < Bmsy). Reduction in the number of overfished stocks has stalled, possible because of an agreement between the European Commission (EC) and the International Council for the Exploration of the Seas (ICES), its advisory body for total allowed catches (TACs), wherein the EC requests ICES to give TAC advice leading to overfishing for many stocks. Scientific advice is often overruled or ignored by politicians/fisheries ministers, whose main objective is to get us much quota as possible for their country. As a result, of the TACs set for 2020, about 46% exceeded scientific advice, suggesting that the goal of ending overfishing in 2020 will not be met.

Accurately measuring the phenotype at the individual level is critical to the success of selective breeding programs. Feed efficiency is a key sustainability trait and is typically approached through feed conversion ratio (FCR). This requires measurements of body weight gain (BWG) and feed intake (FI), the latter being technically challenging in fish. We assessed two of the principal methods for measuring feed intake in fish over consecutive days: (1) group rearing 10 fish per group and video recording the meals and (2) rearing fish individually on a restricted ration. Juvenile Nile tilapia (Oreochromis niloticus) from the Genetically Improved Farmed Tilapia (GIFT) strain and the Cirad strain were entered into the study (128 GIFT and 109 Cirad). The GIFT strain were reared over three consecutive periods of 7 days each under different feeding, recording, and rearing scenarios (i) in groups fed an optimal ration (g100) or (ii) fed a 50% restricted ration (g50) both with video records of all meals and (iii) reared in isolation and fed a 50% restrictive ration. The Cirad strain were tested similarly but only for scenarios (i) and (iii). All fish were fed twice daily with a calculated ration. Correlations showed the same trends for the GIFT and the Cirad strains. For the GIFT strain, correlations were positive and significant for BWG and FI measured in scenarios (i) and (ii), 0.49 and 0.63, respectively, and FI measured in scenarios (i) and (iii) (0.50) but not for BWG measured in scenarios (i) and (iii) (0.29, NS). The phenotypic correlation estimated for FCR between scenarios (i) and (ii) with fish fed an optimal or a 50% restricted ration was low and not significant (0.22). Feed Conversion Ratio for GIFT fish reared in groups or in isolation and fed with a restricted ration [scenarios (ii) and (iii)] were not significantly correlated either. Social interactions between fish, potentially impacting their efficiency, may explain the results. Therefore, selective breeding programs seeking to improve feed efficiency will need to carefully plan the feeding rate and the rearing system used to estimate FCR in order to optimize selection for the targeted production system.

International audience; Viral Nervous Necrosis (VNN, also called viral encephalo- and retinopathy (VER)), is a widespread disease of marine aquaculture caused by betanodavirus (or nervous necrosis virus - NNV), a segmented positive sense RNA virus, member of the nodaviridae family. VNN affects predominantly marine fish and cause significant losses to the Mediterranean fish farming industry, including the production of European sea bass (Dicentrarchus labrax). Of the four circulating genotypes of betanodavirus, red-spotted grouper NNV (RGNNV) and the reassortant geno-type red-spotted grouper/striped jack NNV (RG/SJNNV) are most prevalent in the Mediterranean. Inheritable resistance against VNN has been detected in sea bass, and selective breeding could be a mean to limit this untreatable disease. In the current study, we compare resistance to disease among three populations from the Atlantic Ocean (AT), Eastern Mediterranean (EM) and Western Mediterranean (WM), by challenge trials using both a highly pathogenic isolate of RGNNV and a lower pathogenic reassortant isolate of RG/SJNNV. The sur-vival of the three populations were modelled with a logistic regression, and the odds ratio (OR) of surviving was calculated. The challenge with RG/SJNNV reduced the odds of surviving three-fold (OR =0.29 [0.07-0.87]), whereas the challenge with RGNNV reduced the odds of surviving 100-fold (OR =0.01 [0.00-0.03]). Overall, the EM population had 3.32 (1.92–5.86) times higher odds of surviving the challenge than the AT and WM stocks. All survivors were harboring viral RNA in the brain, as demonstrated by RT-qPCR. However, viral RNA levels were in average lower in survivors from the EM population in both challenges, though only significantly lower in the challenge with RG/SJNNV (p

Size at first sexual maturity (L50) represents an important life-history trait that needs to be considered in the development of management measures as it provides fundamental information for avoiding the exploitation of younger individuals. L50 is known to display variability due to fishing pressure, geographical gradients, and environmental features. In this study, to investigate L50 variability among areas in the Mediterranean and Black Seas, maturity ogives of anchovies (Engraulis encrasicolus) were estimated by considering samples collected during the anchovy spawning period in the framework of the MEDiterranean International Acoustic Survey (MEDIAS) program. Anchovy size and sexual maturity data from several geographical subareas (GSAs), i.e., northern Spain, Gulf of Lion, Tyrrhenian Sea, Strait of Sicily, Adriatic Sea and Black Sea, were gathered according to a standard methodological protocol. Maturity ogives were estimated by a logistic regression considering total length, condition factor, sex and GSA. The obtained results showed a significant effect of the condition factor, in that fish in better condition reached maturity earlier, and the results also indicated differences in L50 values among the areas and between the sexes, with males reaching maturity at lower lengths than females. Even though the obtained L50 estimates are relative to the spawning period only, the variability observed at the Mediterranean basin scale highlights the importance of explicitly considering specific habitat characteristics when providing management advice based on an ecosystem approach for fisheries.

17 pages, 1 table, Cephalopods have become an important global food source, but their sustainable management is challenged by unique life history characteristics associated with short lifespans and semelparous reproduction, high natural mortality rates, rapid and often nonasymptotic growth, and complex population structures. Weak stock-recruitment relationships together with the time-consuming work required for age validation and high-volume annual age determinations make traditional age-based modelling impractical. We propose that the best method for cephalopod assessment involves innovative depletion models, fitted with in-season data on catch numbers and fishing effort, to produce realistic estimates of stock biomass. A “fast lane” assessment approach is suggested that includes high-frequency data collection for separate, in-season stock assessments of each cohort to ensure sustainable exploitation of these short-lived resources. However, most cephalopod fisheries are data-poor and/or lack the infrastructure and resources needed to apply depletion methods; therefore, we also present alternative assessment methods that have been recently applied worldwide. We also offer suggestions for further research on the remaining challenges of cephalopod stock assessment and management, GJP and J-PR acknowledge support from the Cephs & Cephs INTERREG project (EAPA_282/2016). IP acknowledges the Agency ANID of the Government of Chile for a fellowship that partially financed his participation in this review

International audience; Viral Nervous Necrosis (VNN) is a major threat for the European sea bass (Dicentrarchus labrax) aquaculture industry. The improvement of disease resistance through selective breeding is a promising option to reduce outbreaks. With the development of high-throughput genotyping technologies, identification of genomic regions involved in the resistance could improve the efficiency of selective breeding. The aim of this study was to identify quantitative trait loci (QTL) involved in VNN resistance and to quantify their effect.Four experimental backcross families comprising 378, 454, 291 and 211 individuals and two commercial populations A and B comprising 1027 and 1042 individuals obtained from partial factorial crosses (59 male x 20 female for pop A; 39 male x 14 female for pop B) were submitted to a redspotted grouper nervous necrosis virus (RGNNV) challenge by bath. A high-density single nucleotide polymorphism (SNP) chip panel was designed to develop the ThermoFisher Axiom (TM) 57k SNP DlabChip, which was used for genotyping all individuals and building a high quality linkage map. In the backcross families, composite interval mapping was performed on 30,917, 23,592, 30,656 and 31,490 markers, respectively. In the commercial populations, 40,263 markers in pop A and 41,166 markers in pop B were used to perform genome-wide association studies (GWAS) using a GBLUP and a BayesC pi approach.One QTL was identified on chromosome LG12 in three of the four experimental backcross families, and one additional QTL on LG8 was detected in only one family. In commercial populations, QTL mapping revealed a total of seven QTLs, among which the previously mentioned QTL on LG12 was detected in both. This QTL, which was mapped to an interval of 3.45 cM, explained 9.21% of the total genetic variance in pop A, while other identified QTLs individually explained less than 1% of the total genetic variance.The identification of QTL regions involved in VNN resistance in European sea bass, with one having a strong effect, should have a great impact on the aquaculture industry. Future work could focus on the fine mapping of the causal mutation present on LG12 using whole genome sequencing.