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Fish are often speckled with “black spots” caused by metacercarial trematode infection, inducing a host response. Cryptocotyle spp. (Opisthorchiidae) are among the parasites responsible for this phenomenon. So far, the impact on human health is still unknown. In addition, few publications dealing with black spot recovery, identification, distribution and diversity among commercially important fish are available. Moreover, “black spots” have been observed by fishermen on marine fish, revealing an appreciable but unquantified presence in consumed fish. An epidemiological survey of 1,586 fish from seven commercial species (herring, sprat, whiting, pout, dab, flounder, and plaice) was conducted in the Eastern English Channel and the North Sea in January 2019 and 2020. Encysted metacercariae were found in 325 out of 1,586 fish, with a total prevalence of 20.5%. Intensity of infection varied from 1 to 1,104 parasites. The recorded encysted metacercariae were identified either by microscopic examination or with molecular tools. Partial sequences of the mtDNA cox1 gene and of the rDNA ITS region were obtained. Two species of Cryptocotyle, Cryptocotyle lingua (Creplin, 1825) and Cryptocotyle concava (Creplin, 1825) were found. Metacercariae belonging to other trematode families were also identified. Molecular phylogenetic analysis and haplotype network construction were performed to confirm the identification and to study the potential presence of different populations of Cryptocotyle spp. This survey enabled us to describe the distribution of two species of Cryptocotyle in the English Channel and North Sea ecosystems. The observed differences in infestation levels between fish species and geographical areas will contribute to better understanding of the ecology of these parasites., Les poissons sont souvent parsemés de « points noirs » causés par une infection par des métacercaires de trématodes induisant une réponse de l’hôte. Les Cryptocotyle spp. (Opisthorchiidae) font partie des parasites responsables de ce phénomène. Jusqu’à présent, leur impact sur la santé humaine est inconnu. De plus, il existe peu de publications traitant de la récupération, l’identification, la distribution et la diversité des « points noirs » parmi les poisons d’importance commerciale. Par ailleurs, des observations de « points noirs » sur les poissons marins ont été constatées par les pêcheurs révélant une présence assez importante mais non quantifiée dans les poissons consommés. Une enquête épidémiologique portant sur 1 586 poissons de sept espèces commerciales (hareng, sprat, merlan, tacaud, limande, flet et plie) a été menée en Manche orientale et en Mer du Nord, en janvier 2019 et 2020. Des métacercaires enkystées ont été trouvées chez 325 poissons parmi 1 586, avec une prévalence totale de 20,5 %. L’intensité de l’infection variait de 1 à 1 104 parasites. Les métacercaires enkystées répertoriées ont été identifiées soit par examen microscopique, soit avec des outils moléculaires. Des séquences partielles du gène cox1 de l’ADNmt et de la région ITS de l’ADNr ont été obtenues. Deux espèces de Cryptocotyle, Cryptocotyle lingua (Creplin, 1825) et Cryptocotyle concava (Creplin, 1825) ont été trouvées. Des métacercaires appartenant à d’autres familles de trématodes ont également été identifiées. Une analyse phylogénétique moléculaire et la construction d’un réseau d’haplotypes ont été effectuées pour confirmer l’identification et étudier la présence potentielle de différentes populations de Cryptocotyle spp. Cette étude a permis de décrire la distribution de deux espèces de Cryptocotyle dans les écosystèmes de la Manche et de la Mer du Nord. Les différences observées dans les niveaux d’infestation entre les espèces de poissons et les zones géographiques contribueron

The International Bottom Trawl Survey Working Group (IBTSWG) coordinate fishery-independent bottom trawl surveys in the ICES Area (Northeast Atlantic and North Sea) providing an important platform for the collection of additional data such as sampling larval sprat, stomach contents and fish parasites. These long-term monitoring surveys provide data for stock assessments and facilitate analyses of the distributions and relative abundance of fish. IBTSWG promotes the standardization of fishing gears and methods. This report summarizes national contributions in 2022–2023 and plans for the 2023–2024 surveys. In the North Sea, the surveys are performed in Quarter 1 and Q3. The Northeast Atlantic surveys are conducted mostly in Q1, Q3, and Q4 with a suite of 14 national surveys covering large areas of continental shelf extending from northern Scotland to the Gulf of Cádiz. The 2023-Q1 North Sea IBTS was impacted slightly by mechanical issues on one vessel, resulting in some of the Rectangles in the central North Sea being sampled with a single haul instead of the planned two. The 2022-Q3 North Sea IBTS was broadly complete, with the overall number of hauls comparable to previous years, though some Rectangles close to shore or with obstructions may not have had full coverage. The Northeast Atlantic surveys were mostly completed successfully, with the exception of the Scottish west coast groundfish survey in Q1 (cancelled due to vessel breakdown). There was incomplete survey coverage for some of the surveys, including the EVHOE survey (severe weather) and Portuguese groundfish survey (severe weather and mechanical problems). The Spanish surveys in the Gulf of Cádiz (cancelled in 2021) were undertaken in 2022. Recent updates to DATRAS, where the trawl survey data are stored, were summarised and data quality, including catch weights and species identification, was reviewed. IBTSWG met with members of various data users, including r

Chemical contaminant concentrations in wild organisms are used to assess environmental status under the European Marine Strategy Framework Directive. However, this approach is challenged by the complex intra- and inter-species variability, and the different regional features. In this study, concentrations in trace elements (As, Cd, Hg and Pb), polychlorinated biphenyls (PCBs), polychlorodibenzo-para-dioxines (PCDDs) and polychlorodibenzofuranes (PCDFs) were monitored in 8 fish species sampled on the continental shelf of three French regions: the Eastern English Channel (EEC) and Bay of Biscay (BoB) in the Northeast Atlantic Ocean, and the Gulf of Lions (GoL) in Western Mediterranean Sea. Our objectives were to identify species or regions more likely to be contaminated and to assess how to take this variability into account in environmental assessment. While concentrations were higher in benthic and demersal piscivores, PCB and PCDD/F concentrations (lipid-weight) were similar in most teleost species. For Cd, Hg and Pb, the trophic group accumulating the highest concentrations depended on the contaminant and region. Concentrations in Hg, PCBs and PCDD/Fs were higher in the EEC and/or GoL than in BoB. Cadmium and Pb concentrations were highest in the BoB. Lipid content accounted for 35%–84% of organic contaminant variability. Lipid normalisation was employed to enhance robustness in the identification of spatial patterns. Contaminant patterns in chondrichthyans clearly differed from that in teleosts. In addition, trophic levels accounted for ≤1% and ≤33% of the contaminant variability in teleost fishes in the EEC and BoB, respectively. Therefore, developing taxa-specific thresholds might be a more practical way forward for environmental assessment than normalisation to trophic levels.

L’Unité de recherche HMMN, créée en 2005, appartient depuis 2011 au Département Ressources Biologiques et Environnement (RBE), qui est l’un des 4 Département scientifiques de l’IFREMER, avec les Départements Océanographie et Dynamique des Ecosystèmes (ODE), Recherches physiques et Ecosystèmes de fond de Mer (REM) et Infrastructures de Recherche et Systèmes d’Information (IRSI). L’Unité de recherche HMMN est constituée de deux laboratoires, l’un situé à Boulogne sur mer dans les Hauts de France (LRHBL) et l’autre à Port-en-Bessin en Normandie (LRHPB). Ces deux laboratoires, ainsi que les autres laboratoires des Départements ODE et REM localisés à Boulogne s/mer et Port-en-Bessin (ODE: deux Laboratoires Environnement Ressources, LERBL et LERN; REM: un Laboratoire Comportement des Structures en Mer, LCSM), sont rattachés administrativement au Centre de Manche – Mer du Nord (CMMN) de l’IFREMER. L’équipe HMMN effectue des recherches en écologie marine et halieutique, principalement centrées sur les écosystèmes de Manche et Sud mer du Nord. Ces recherches trouvent un prolongement dans l’appui aux politiques publiques concernant la conservation des écosystèmes marins et l’aménagement des pêcheries et d’autres usages du domaines maritime (e.g., extraction de sables et granulats marins, production d’énergies marines renouvelables), dans un contexte de changement climatique. L’unité HMMN contribue à la collecte de données halieutiques et écosystémiques en mer, par enquêtes, et en laboratoire, et centralise à travers la cellule CREDO, le traitement et l’envoi des données halieutiques requises par une variété d’organismes scientifiques, gestionnaires, professionnels et non gouvernementaux. HMMN coordonne trois campagnes en mer à grande échelle régionale et héberge trois infrastructures technologiques: un Pôle National de Sclérochronologie (PNS), une Plateforme Réseaux Trophiques (PRT), et un Pôle de Taxinomie et d’Ecologie du Zooplancton (PTEZOO). En cherchant à mieux comprendr

The parasitic barnacle, Anelasma squalicola, is a rare and evolutionary fascinating organism. Unlike most other filter-feeding barnacles, A. squalicola has evolved the capability to uptake nutrient from its host, exclusively parasitizing deepwater sharks of the families Etmopteridae and Pentanchidae. The physiological mechanisms involved in the uptake of nutrients from its host are not yet known. Using stable isotopes and elemental compositions, we followed the fate of nitrogen, carbon and sulphur through various tissues of A. squalicola and its host, the Southern lanternshark Etmopterus granulosus, to better understand the trophic relationship between parasite and host. Like most marine parasites, A. squalicola is lipid-rich and clear differences were found in the stable isotope ratios between barnacle organs. It is evident that the deployment of a system of ‘rootlets’, which merge with host tissues, allows A. squalicola to draw nutrients from its host. Through this system, proteins are then rerouted to the exterior structural tissues of A. squalicola while lipids are used for maintenance and egg synthesis. The nutrient requirement of A. squalicola was found to change from protein-rich to lipid-rich between its early development stage and its definitive size.

The International Bottom Trawl Survey Working Group (IBTSWG) coordinates fishery-independent bottom trawl surveys in the ICES area in the Northeast Atlantic and the North Sea. These long-term monitoring surveys provide data for stock assessments and facilitate examina-tion of changes in fish distribution and relative abundance. The group also promotes the stand-ardization of fishing gears and methods as well as survey coordination. This report summarizes the national contributions in 2021–2022 and plans for the 2022–2023 surveys coordinated by IBTSWG.

The International Bottom Trawl Survey Working Group (IBTSWG) coordinates fishery-independent bottom trawl surveys in the ICES area in the Northeast Atlantic and the North Sea. These long-term monitoring surveys provide data for stock assessments and facilitate examination of changes in fish distribution and relative abundance. The group also promotes the standardization of fishing gears and methods as well as survey coordination. This report summarizes the national contributions in 2021–2022 and plans for the 2022–2023 surveys coordinated by IBTSWG. In the North Sea, the surveys are performed in quarters (Q) Q1 and Q3, while in the Northeast Atlantic the surveys are conducted in Q1, Q3, and Q4 with a suite of 14 national surveys covering a large area of continental shelf that extends from the north of Scotland to the Gulf of Cádiz. North Sea surveys in 2022-Q1 were affected severely by mechanical and COVID-related issues, as well as the number of storms experienced during the survey period. Some of the ICES rectangles in the survey area could not be sampled and a larger number of the rectangles were only sampled with a single tow. North Sea surveys in 2021-Q3 were broadly complete, with the wider area surveyed and comparable number of hauls. However, some rectangles close to shore or with obstructions may not have had full coverage. Most of the surveys in the Northeast Atlantic were completed successfully. However, the two Spanish groundfish surveys in the Gulf of Cádiz could not be undertaken in 2021. Vessel-related problems also affected the Spanish survey of the Cantabrian Sea, although this survey was completed using two vessels over a more protracted survey window. The IBTSWG welcomed the return of the Portuguese groundfish survey (Q4) after a two-year absence, with the survey being undertaken by the new research vessel, the “Mario Ruivo”. IBTSWG discussed the roadmap for the new survey trawl, following on from the Workshop o

Les estuaires sont des zones qui jouent un rôle clé dans le fonctionnement des écosystèmes marins, notamment au travers de leur fonction de nourricerie. L’estuaire de la Seine agit ainsi comme nourricerie pour plusieurs espèces de poissons, en particulier le bar, le merlan, la sole et la plie. Ces quatre espèces d’intérêt halieutique ont donc été ciblées dans le projet CAPES. Les nourriceries agissent comme des zones tampons : seul un certain nombre d'individus survivra au premier été. Ce nombre est défini par les caractéristiques de la nourricerie (i.e. capacité d’accueil). Compte tenu des profondes modifications morphologiques subies et des conséquences induites sur les différents habitats de l’estuaire externe de la Seine, il est essentiel d’en appréhender le fonctionnement de cet écosystème pour comprendre si ces modifications ont altéré le rôle de nourricerie. Dans le cadre du projet CAPES, nous avons abordé cette capacité d’accueil via le volet trophique en testant l’hypothèse que les ressources alimentaires sont limitantes et jouent un rôle de régulation des abondances de juvéniles de poissons. Nous nous sommes intéressés à la variabilité et la connectivité des différents habitats de l’estuaire externe de la Seine. Les objectifs du projet étaient (1) de décrire et quantifier la variabilité inter-habitats (Fosse Nord, Fosse Sud, Embouchure, Chenal de navigation et Vasières Nord intertidales) et temporelle (interannuelle et saisonnière) des différentes composantes biologiques (méiofaune, zooplancton, suprabenthos, macrofaune benthique et poissons) de l’estuaire externe de la Seine, (2) de décrire le fonctionnement trophique des différents habitats, afin d’identifier des habitats à fortes contributions trophiques pour les différentes espèces étudiées, et (3) d’estimer la capacité trophique à l’échelle des habitats sur plusieurs années et entre deux saisons pour identifier les habitats en limitation trophique potentielle et également la période à laquelle s’effec

This document summaries major information about the diet of mackerel Scomber scombrus in the English Channel, collected during the VARITROPH project. Mackerel consume quite exclusively copepods, with low effect of size on both diet and trophic level., Ce document résume les principaux résultats obtenus concernant l'alimentation du maquereau Scomber scombrus en Manche, dans le cadre du projet VARITROPH. Le maquereau consomme quasi exclusivement des copépodes, avec peu de variations liées à la taille.

This document summaries major results about the diet of sole Solea solea and plaice Pleuronectes platessa in the English Channel, collected in the framework of the VARITROPH project. Both species have a similar diet, based on crustaceans, but plaice exhibit a larger diversity of secundary species (bivalves, annelids and echinoderms) than sole (annelids only). Diversity of the preys for plaice is explained by differences between size classes. Diet of small individuals is less diverse than the diet of large individuals. Trophic similarity between sole and plaice is also exhibited when comparing ontogenic changes of trophic levels, that are pretty similar for both species, and consistent with a diet based on small invertebrates., Ce document résume les principaux résultats obtenus concernant l'alimentation de la sole Solea solea et de la plie Pleuronectes platessa en Manche, obtenus dans le cadre du projet VARITROPH. Les deux espèces de poissons plats ont une alimentation comparable, principalement basée sur les crustacés. La plie montre cependant une plus grande diversité de proies secondaires (bivalves, annélides et échinodermes) que la sole (annélides seulement). La diversité des proies pour la plie s'explique par les différences de diversité alimentaire entre classes de taille. Les petits individus ont une alimentation moins diverse que les grands. Cette similarité entre sole et plie se retrouve pour le niveau trophique, relativement comparable entre les deux espèces et cohérent avec une alimentation basée sur des petits invertébrés.

The ability to efficiently implement ecosystem-based fisheries management is largely dependent on data availability. As invertebrates are not included in routine monitoring programmes, data should be collected by different approaches. We assessed whether fish could be suitable biological samplers of benthic invertebrates in the Eastern English Channel by comparing spatial distributions of Galatheidae, Portunidae and Porcellanidae found in digestive tracts (DTs) from a fish survey (Channel Ground Fish Survey), and in a dedicated benthos survey (Eastern English Channel Benthic Survey, ECBS). We found a significant spatial match between the distributions of Porcellanidae, Galatheidae and Portunidae found in fish DTs, and the ECBS occurrence-based maps. The strongest overlap was found for Galatheidae. Spatial distributions of Porcellanidae based on fish DTs better overlapped those derived from dedicated benthos surveys when we assumed these prey to also be consumed in the neighbouring spatial units to where fish were sampled. This might reflect the relatively high mobility of the dominant predators of Porcellanidae (e.g. Mustelus asterias, Scyliorhinus canicula). Overall, this study demonstrated that fish diet sampling can provide valuable information on the spatial distribution of benthic organisms.

Opportunistic records, especially for rare species, are often the first available data revealing geographic expansions in a context of global change in marine ecosystems. On the basis of a first record in the north of the North Sea of the mesopelagic fish Diretmichthys parini (Post and Quéro, 1981), initially described as tropical and subtropical, a hypothesis of geographical expansion in relation to global warming was formulated in 2017. The analysis of a larger set of spatial and temporal data, including historical (1992-2016) records from Iceland and recent (2017-2021) records from Norway, induces a revision of this hypothesis and makes it possible to reconsider the thermal preferences of the adults of this species. The new importance of social media as a tool to monitor records is also highlighted, as pictures of unusual fishes are frequently being posted there., Les signalements opportunistes, notamment pour les espèces rares, sont souvent les premières données disponibles révélant des expansions géographiques dans un contexte de changement global des écosystèmes marins. Sur la base d’un premier signalement au nord de la mer du Nord du poisson mésopélagique Diretmichthys parini (Post et Quéro, 1981), initialement décrit comme tropical et subtropical, une hypothèse d’expansion géographique en relation avec le réchauffement climatique a été formulée en 2017. L’analyse d’un plus grand jeu de données spatiales et temporelles, incluant notamment des signalements anciens (1992-2016) en Islande et récents en Norvège (2015-2017), induit la révision de cette hypothèse et permet de reconsidérer les préférences thermiques des adultes de cette espèce. Ce travail illustre également l’importance de prendre en compte les réseaux sociaux pour suivre les signalements opportunistes, car la surprise liée à la capture de ces poissons inhabituels y entraîne souvent la publication des photos par le grand public.

The International Bottom Trawl Survey Working Group (IBTSWG) coordinates fishery-inde-pendent multispecies bottom-trawl surveys within the ICES area. These long-term monitoring surveys provide data for stock assessments and facilitate examination of changes in fish distri-bution and abundance. The group also promotes the standardization of fishing gears and meth-ods and survey coordination. This report summarizes the national contributions in 2020–2021 and plans for the 2021–2022 surveys coordinated by IBTSWG. In the North Sea, the surveys are performed in quarters (Q) Q1 and Q3 while in the Northeast Atlantic the surveys are conducted in Q1, Q3, and Q4 with a suite of 14 national surveys covering a large area of continental shelf that ranges from North of Scotland to the Gulf of Cádiz. Despite the COVID-measures and bad weather, most surveys were able to complete the majority of the planned hauls. The Portuguese survey (PT-GFS-Q4) was cancelled in 2020 due to issues associated with the new vessel and a COVID-outbreak. A COVID-related delay in submitting the cruise application form for the French CGFS20 survey resulted in no authorisation to trawl in UK waters and only 70% of the core stations were completed. Issues with the UK permits, were also experienced in the North Sea surveys, only being resolved at the last moment, expected to be a returning issue. Therefore, IBTSWG addressed the permit issue in further detail in order to better evaluate the impact and propose possible solutions. All surveys, except for the Spanish GCGF-Q1 21 which is cancelled due to a vessel refit, are planned to take place according to the manuals in the next year. The SCOROC Q3 20 survey recorded second highest recruitment of zero group haddock on the Rockall Bank since the start of the new survey series in 2011. The North Sea Q1 21 survey rec-orded good recruitment of haddock as well, and high recruitment of mackerel, while overall herring recruitment seemed low except for three excepti

Organisms are exposed to various stressors including parasites and micropollutants. Their combined effects are hard to predict. This study assessed the trophic relationship, micropollutants bioaccumulation and infection degree in a host-parasite couple. Carbon and nitrogen isotopic ratios were determined in hake Merluccius merluccius muscle and in its parasite Anisakis sp.. Concentrations of both priority (mercury species and polychlorinated biphenyls congeners) and emerging (musks and sunscreens) micropollutants were also measured for the parasite and its host, to detect potential transfer of contaminants between the two species. The results showed partial trophic interaction between the parasite and its host, in accordance with the Anisakis sp. life encysted in hake viscera cavity. PCB transfer between the two species may result from some lipids uptake by the parasite, while no relation occurred for the two other contaminants. Finally, a positive correlation was found between the number of Anisakis sp. larvae and the methylmercury contamination for hake, emphasizing the assumption that the contamination level in methylmercury can weaken immune system of the host enough to affect parasite infection degree.