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Nearshore habitats are essential for many marine fish species but are subject to anthropogenic stressors. Assessing the consequences of essential fish habitat degradation on population dynamics and productivity is challenging. We address this by focusing on a metapopulation of the common sole Solea solea, a high-value, exploited flatfish in the Eastern English Channel (EEC). Multidisciplinary data and expert knowledge were compiled to build feasible restoration scenarios for the availability of suitable habitat (measured in habitat surface extent) and chemical quality of juvenile habitats in the highly anthropized Seine estuary, the largest estuary and potentially a sole nursery area of primary interest in the EEC. Scenarios were simulated with a spatially structured life-cycle model to investigate the consequences of local restoration on restricted nursery habitats in the estuary. Restoring surface extent and habitat quality in the Seine estuary dramatically enhances spawning stock biomass (+18%) and fishery catches (+13%) in the EEC. Restoring habitat quality has a greater effect than restoring habitat surface. Because of the low connectivity between subpopulations of sole in the EEC, most of the local restoration benefits remain regional and affect the subpopulation that directly depends on the Seine nursery, with only moderate spread to the entire EEC. Our study emphasizes the utility of spatial simulation models for integrating multidisciplinary knowledge and assessing the consequences of local anthropogenic pressures at wider metapopulation scales. We provide a means of building robust methods to assess the benefits of nearshore habitat restoration for enhancing fish populations and fisheries and integrate habitat value into the sustainable management of exploited species.

The total length-otolith length (TL-OL), total length-otolith width (TL-OWi), total length-otolith weight (TL-OW) and total weight-otolith weight (TW-OW) relationships of seven fishes in the Marmara Sea, Turkey were calculated. Measurements of sagittal otoliths (length, width and weight) and individuals (total length and total weight) from these species (Gaidropsarus biscayensis, Mediterranean bigeye rockling; Arnoglossus kessleri, Scaldback; Solea solea, Common sole; Uranoscopus scaber, Stargazer; Lophius budegassa, Blackbellied angler, Lepidorhombus boscii, The four-spot megrim and Lesueurigobius friesii, Fries's goby) were given. Linear regression analysis (y = bx + a) was used to determine the relationship between each morphometric character and the coefficient of determination (r2) were calculated. Highest determination coefficient were determined for L. budegassa and A. kessleri to TW-OW, for S. solea, and U. scaber to TL-OL, for G. biscayensis and L. boscii to TL-OWi, for L. friesii to TL-OW. The relatively lower determination coefficients were found for G.biscayensis, compared with others. These relationships provide vital information on species identification and size estimation of fish in predator-prey studies, we believe these results will be useful in future studies of stomach contents., Marmara Denizi’nde ki 7 balık türünde balık boyu-otolit boyu (TL-OL), balık boyu-otolit genişliği (TL-OWi), balık boyu-otolit ağırlığı (TL-OW) ve balık ağırlığı-otolit ağırlığı (TW-OW) ilişkileri hesaplanmıştır. Bu türlere ait (Gaidropsarus biscayensis, Uzun Gelincik; Arnoglossus kessleri, Pisi Balığı; Solea solea, Dil Balığı; Uranoscopus scaber, Tiryaki; Lophius budegassa, Fener Balığı; Lepidorhombus boscii, Kancaağız Pisi ve Lesueurigobius friesii, Kaya Balığı) balık ölçümleri (boy ve ağırlık) ve otolit ölçümleri (boy, genişlik ve ağırlık) verilmiştir. Her bir morfolojik karakteristiğin arasındaki ilişkilerin tespitinde Doğrusal regresyon analizi (y = bx + a) kullanılmış ve determinasyon katsayısı (r2) hesaplanmıştır. En yüksek determinasyon katsayısı L. budegassa ve A. kessleri için TW-OW, S. solea, ve U. scaber için TL-OL, G. biscayensis ve L. boscii için TL-OWi, L. friesii için TL-OW ilişkilerinde hesaplanmıştır. Diğer türlerle karşılaştırıldığında, G. biscayensis için oldukça düşük determinasyon katsayıları bulunmuştur. Bu ilişkiler balıkların av-avcı ilişkileri çalışmalarında tür tayini ve av boyu tahmininde önemli bilgiler sunduğundan, gelecekte gerçekleştirilecek mide içeriği çalışmaları açısından katkı sağlayacağını düşünmekteyiz.

Fish fraud is a problematic issue for the industry. For it to be properly addressed will require the use of accurate, rapid, and cost-effective tools. In this work, near infrared reflectance spectroscopy (NIRS) was used to predict nutritional values (protein, lipids, and moisture) as well as to discriminate between sources (farmed vs. wild fish) and conditions (fresh or defrosted fish). Samples of five whitefish species—Alaskan pollock (Gadus chalcogrammu), Atlantic cod (G. morhua), European plaice (Pleuronectes platessa), common sole (Solea solea), and turbot (Psetta maxima)—including farmed, wild, fresh, and frozen ones, were scanned by a low-cost handheld near infrared reflectance spectrometer with a spectral range between 900 and 1700 nm. Several machine learning algorithms were explored for both regression and classification tasks, achieving precisions and coefficients of determination higher than 88% and 0.78, respectively. Principal component analysis (PCA) was used to cluster samples according to classes where good linear discriminations were denoted. Loadings from PCA revealed bands at 1150, 1200, and 1400 nm as the most discriminative spectral regions regarding classification of both source and condition, suggesting the absorbance of OH, CH, CH2, and CH3 groups as the most important ones. This study shows the use of NIRS and both linear and non-linear learners as a suitable strategy to address fish fraud and fish QC.

Larval dispersal and juvenile survival are crucial in determining variation in recruitment, stock size and adult distribution of commercially important fish. This study investigates the dispersal of early-life stages of common sole (Solea solea L.) in the southern North Sea, both empirically and through modeling. Age at different life-history events of juvenile flatfish sampled along the coasts of Belgium, the Netherlands and the United Kingdom in 2013, 2014 and 2016, was determined through the counting of daily growth rings in the otoliths. Juveniles captured between August and October were estimated to be on average 140 days old with an average pelagic larval duration of 34 days. The hatching period was estimated between early April and mid-May followed by arrival and settlement in the nurseries between May and mid-June. Growth rates were higher off the Belgian coast than in the other nursery areas, especially in 2013, possibly due to a post-settlement differentiation. Empirical pelagic larval duration and settlement distributions were compared with the Larvae&Co larval dispersal model, which combines local hydrodynamics in the North Sea with sole larval behavior. Yearly predicted and observed settlement matched partially, but the model estimated a longer pelagic phase. The observations fitted even better with the modelled average (1995-2015) distribution curves. Aberrant results for the small juvenile sole sampled along the UK coast in March 2016, led to the hypothesis of a winter disruption in the deposition of daily growth rings, potentially related to starvation and lower food availability. The similarities between measured and modelled distribution curves cross-validated both types of estimations and accredited daily ageing of juveniles as a useful method to calibrate biophysical models and to understand early-life history of fish, both important tools in support of efficient fisheries management strategies. ispartof: PLOS ONE vol:16 issue:9 ispartof: location:United States status: published

The otolith, found in both inner ears of bony fish, has mainly been used to estimate fish age. Another application that has been developing significantly in recent years, however, is the use of otolith shape as a tool for stock identification. Often, studies have directly used the shape asymmetry between the right and left otoliths. We tested the magnitude of directional asymmetry between the sagittal otoliths (left vs. right) of 2991 individuals according to their catch locations, and we selected species to evaluate whether directional asymmetry may itself be a tool to evaluate stock boundaries. Elliptical Fourier descriptors were used to describe the otolith shape. We used a flatfish, the common sole (Solea solea, n = 2431), from the eastern English Channel and the southern North Sea as well as a roundfish, the bogue (Boops boops, n = 560), from the Mediterranean Sea. Both species showed significant levels of directional asymmetry between the testing locations. The bogue otoliths showed significant asymmetry for only 5 out of 11 locations, with substantial separation between two large areas: the Algerian coast and the western part of the Italian coast. The sole otoliths showed significant asymmetry in the shape analysis (3.84–6.57%), suggesting a substantial separation between two large areas: the English and French parts of the English Channel and the southern North Sea. Consequently, directional bilateral asymmetry in otolith shape is a potential new method for stock identification., Biología de recursos vivos de Canarias, PACA-BIO, SI

Populations along environmental gradients have the potential to adapt to their own local environments. It is important to understand these adaptations in fisheries stocks to fully inform fisheries management strategies. With this is mind, sea temperatures are an important cue in timing for many marine species, including sole in the North-East Atlantic Ocean. We used spawning data and modelled sea surface temperature (SST) data from sole subpopulations to examine the possibility of local adaptation of their spawning times to rising temperature. Climate window analysis was used, in a linear mixed model using mean spawning week and SST, to investigate statistically significant differences between subpopulations of sole. There was no evidence of local adaptation to changing temperatures for these subpopulations. This suggests that their spawning-time reaction to changing temperatures is currently due to their subpopulation’s mean plasticity. Using climate window analysis and modelled temperature data we have demonstrated a method of examining spawning changes in marine populations along a temperature gradient. Recruitment and spawning success are key elements of fisheries population models which contribute to fisheries management. Further understanding of the influence of temperature on recruitment will help inform future modelling.

Summary The metazoan parasites were investigated of two flatfish the common sole, Solea solea (n:140) and the scaldfish, Arnoglossus laterna (n: 22) in the Sinop coast of Black Sea from June 2015 to June 2017. A total of 15 metazoan parasite species belonging to Digenea (6), Cestoda (3), Acanthocephala (1), Nematoda (4) and Isopoda (1) taxonomic groups were identified. Solea solea was found to be infected by Condylocotyla pilodora, Proctoeces maculatus, Opecoelidae gen. sp., Metadena sp., Stephanostomum sp., Progrillotia sp., Capillaria gracilis, Cucullanus campanae, Solearhynchus rhytidotes and Nerocila orbignyi. Arnoglossus laterna was found to be infected by Lecithochirium musculus and Grillotia erinaceus. Scolex pleuronectis, Hysterothylacium aduncum and Dichelyne minutus were determined in both flatfish. Infection prevalence and mean intensity values were re- corded for each parasite species. Infection values for each parasite species in relation to season and fish size were also determined and compared as comparatively. This study is the first one assessing the metazoan parasites both of S. solea and A. laterna collected from the Turkish coast of Black Sea. While Condylocotyle pilodora and Capillaria gracilis are new parasite records for S. solea, Grillotia erinecaus is new parasite record for A. laterna. Moreover, this paper is the first report on occurrence of Opecoelidae gen. sp., Metadena and Stephanostomum genera in S. solea.

Connectivity between juvenile habitats and adult stocks is important for determining the resilience of local fisheries and the relative contribution of different juvenile habitat areas to adult populations. Otolith chemistry is commonly employed to differentiate between individuals from different juvenile habitat areas; whereby different environmental exposures, mediated by intrinsic physiological processes, produce different trace element concentrations in the biologically inert otolith. This study aims to determine if otolith chemistry can differentiate between juveniles of hybridising con-familials where they are found in the same habitat and to establish if otolith chemistry can effectively re-assign individuals to contiguous coastal juvenile habitat areas of the inner Danish waters (IDW). Sympatric pairs of juvenile European plaice (Pleuronectes platessa) and flounder (Platichthys flesus) caught together in a juvenile beam trawl survey, in areas where the two species hybridise, were used to address the first aim. Juvenile plaice and common sole (Solea solea) caught during the same survey were used to determine if otolith chemistry can correctly re-assign individuals back to contiguous coastal juvenile habitat areas. Laser ablation inductively coupled plasma mass spectroscopy (LA-ICPMS) was used to analyse the trace elements in edge spots of juvenile otoliths and Canonical Analysis of Principal Coordinates was employed to test the reassignment of individuals back to correct species or area. Using a suite of eight trace elements, ∼72% of individual plaice (∼70%) and flounder (∼73%) were correctly identified. Greater than two-thirds (∼67%) of plaice were correctly re-allocated to four juvenile habitat areas and close to four out of five (∼79%) individual sole were correctly re-allocated to three juvenile habitat areas. These results indicate that the hybridising con-familial plaice and flounder of the IDW warrant further attention and could be a valuable model system to assess how intrinsic and extrinsic factors influence elemental incorporation. Furthermore, this study shows otolith chemistry is a valuable tool for tracing marine fish back to juvenile habitat areas, even where they are found along contiguous coastal areas.

The existence of a temperature gradient across latitudes is crucial to explain the patterns presented in the early life-history characteristics of marine fish species over large geographical areas. Hence, the aim of the present work was to analyse the temperature-related pattern in the early life-history events and characteristics of the common sole, Solea solea, along most of its geographical distribution area, focusing on key nursery areas for this species: Venice lagoon (Italy), Mondego estuary (Portugal), Vilaine estuary (France) and Balgzand (Netherlands). Otolith microstructure from metamorphosed age 0 juveniles was used to estimate age, the pelagic larval and metamorphosis stages duration, and the spawning period. A latitudinal cline was found for the main processes of the early life cycle: spawning started in December in the southernmost areas (Mondego estuary and Venice Lagoon) and in February in the Balgzand population. Hatching started earlier in the Venice lagoon, where warmer water temperatures in the winter led to an earlier development. The longest pelagic stage was observed in the French coast populations, which differed significantly from those of the Mediterranean, while metamorphosis lasted longer in the North Sea (Balgzand), when compared with the Portuguese Atlantic coast (Mondego). Populations further north were characterized by higher growth rates, suggesting an adaptation to local conditions. Despite that several abiotic factors play an important role in flatfish early life history, the observed temperature gradient seems to be one of the most important drivers.

Recent important developments in sole aquaculture have increased the availability of the farmed product on the market. The aim of this research was to characterize and compare for the first time in common sole (Solea solea) morphometric parameters, nutrients and sensory traits of cultured and wild specimens. Farmed sole, while maintaining the characteristics of a lean fish species (2% of lipid content), displayed a EPA+DHA fillet content more than twice as high as its wild counterpart. Sensory traits of “potato”, “boiled fish”, sweet, firmness, astringency, chewiness, were correlated to farmed origin while whiteness, briny, “octopus”, “crab”, salty, acid, bitter, umami, intensity and juiciness were linked to wild origin. Intensive farming conditions improved the nutritional value of common sole in terms of lipid content and fatty acid profile and led to sweeter sensory traits particularly associated with a terrestrial vegetable perception.

Sole fed commercial pellets develop a nutritional anaemia. This study assessed the impact of dietary B12 and taurine on the haematocrit (Hct) and haemoglobin (Hb) level and mineral absorption in anaemic sole. Anaemic sole was fed one of four diets. Diets were equal regarding mineral, amino acid and macronutrient composition and formulated, according to a two by two factorial design: two B12 (0.34 vs. 1.9 mg kg dm⁻¹) and two taurine levels (3.5 vs. 7.6 mg kg dm⁻¹). The feeding level was restricted and equal for all diets. Hct and Hb levels in anaemic sole are influenced by dietary B12. A “high” level of B12 increases the Hct and Hb level. An increasing level of taurine suppresses the stimulating effect of the “high” level of B12. The applied B12 and taurine levels were unable to completely alleviate the anaemia in sole. Nevertheless, sole needs high dietary levels of B12 to alleviate anaemia. The impact of B12 and taurine on Hb and Hct was not related to a change in the absorption of iron. A “high” level of B12 positively affected the absorption of chromium and a high level of taurine negatively affected the absorption of cobalt in sole.

This study extends our knowledge of the bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) in marine organisms and investigates its possible determinants. PAH levels were measured in Solea solea tissue and in marine sediments collected from three areas of the northern Adriatic Sea characterized by different anthropic impacts (Venetian Lagoon, Po Delta, and fishing grounds off Chioggia). The possibility of differential PAH bioaccumulation in different tissues (muscle, liver and gills) was investigated by seeking relationships between mean individual and total PAH concentrations in tissue and sediment samples, the physicochemical properties of PAHs (rings and Kow), and some key biological variables (lipid content of tissues, body size, habitat). The present study demonstrated that the lipid content might not be the only determinant of PAH bioaccumulation in common sole tissues. The habitat characteristics, the tissue types and some physicochemical properties of compounds were closely related to PAH bioaccumulation.

Electrical pulse trawling is an alternative to conventional beam trawling for common sole (Solea solea), with the potential for higher revenues and less impact on the marine ecosystem. Concerns exist, however, that benthic invertebrates might be seriously affected by pulse fishing. Even if direct injuries and mortality were limited, changes in behaviour might compromise their survival, with potentially large impacts on food webs. Here, we investigate effects of electrical pulses on locomotion behaviour and 14-days survival of six invertebrate species from four phyla that may encounter pulse fishing gears. Electrical stimulation consisted of a Pulsed Bipolar Current at 200 V m–1, 30 Hz, 0.33 ms pulse width, and 3 s duration. We quantified species-specific behaviours before, during, and after electrical stimulation and compared these to a non-exposed control group. Responses during stimulation varied from no visible effect (echinoderms) to squirming (sea mouse) and retractions (whelk and crustaceans). Within 30 s after stimulation, all animals resumed normal behavioural patterns, without signs of lasting immobilisation. Starfish, serpent star, whelk and sea mouse showed no change in movement patterns after stimulation, whereas flying crab and hermit crab showed significant changes in activity that were indicative of increased shelter behaviour. For none of the species, survival at 14-days after stimulation was negatively affected. These findings suggest that changes in locomotion behaviour due to electrical stimulation as used in pulse trawling are unlikely to substantially compromise survival of the investigated species.

Information on stock status is available only for a few of the species forming the catch assemblage of rapido fishery of the North-central Adriatic Sea (Mediterranean Sea). Species that are caught almost exclusively by this gear, either as target (such as Pectinidae) or accessory catches (such as flatfishes apart from the common sole), remain unassessed mainly due to the lack of data and biological information. Based on cluster analysis, the catch assemblage of this fishery was identified and assessed using CMSY model. The results of this data-poor methodology showed that, among the species analyzed, no one is sustainably exploited. The single-species CMSY results were used as input to an extension of the same model, to test the effect of four different harvest control rule (HCR) scenarios on the entire catch assemblage, through 15-years forecasts. The analysis showed that the percentage of the stocks that will reach Bmsy at the end of the projections will depend on the HCR applied. Forecasts showed that a reduction of 20% of fishing effort may permit to most of the target and accessory species of the rapido trawl fishery in the Adriatic Sea to recover to Bmsy levels within 15 years, also providing a slight increase in the expected catches.

Marine organisms show population structure at a relatively fine spatial scale, even in open habitats. The tools commonly used to assess subtle patterns of connectivity have diverse levels of resolution and can complement each other to inform on population structure. We assessed and compared the discriminatory power of genetic markers and otolith shape to reveal the population structure on evolutionary and ecological time scales of the common sole (Solea solea), living in the Eastern English Channel (EEC) stock off France and the UK. First, we genotyped fish with Single Nucleotide Polymorphisms to assess population structure at an evolutionary scale. Then, we tested for spatial segregation of the subunits using otolith shape as an integrative tracer of life history. Finally, a supervised machine learning framework was applied to genotypes and otolith phenotypes to probabilistically assign adults to subunits and assess the discriminatory power of each approach. Low but significant genetic differentiation was found among subunits. Moreover, otolith shape appeared to vary spatially, suggesting spatial population structure at fine spatial scale. However, results of the supervised discriminant analyses failed to discriminate among subunits, especially for otolith shape. We suggest that the degree of population segregation may not be strong enough to allow for robust fish assignments. Finally, this study revealed a weak yet existing metapopulation structure of common sole at the fine spatial scale of the EEC based on genotypes and otolith shape, with one subunit being more isolated. Our study argues for the use of complementary tracers to investigate marine population structure. ispartof: PLOS ONE vol:15 issue:11 ispartof: location:United States status: published

The evolution of a permanent separation of the upper respiratory and digestive tract is one of the adaptions cetaceans evolved for their aquatic life. Generally, it prevents odontocetes from choking on either saltwater or foreign bodies during ingestion under water. Nevertheless, several sporadic single case reports from different parts of the world show that this separation can be reversed especially by overly large items of prey. This incident can have a fatal outcome for the odontocetes. The German federal state of Schleswig-Holstein has a year-round, permanent and systematic stranding network that retrieves stranded marine mammals from its shorelines and constantly enables post-mortem examinations. In 2016, with nine affected animals, a high incidence of fatal pharyngeal entrapment of flatfish in harbour porpoises (Phocoena phocoena) occurred during spring and early summer on the German North Sea island of Sylt. All flatfish were identified as common sole (Solea solea). A retrospective post-mortem data analysis over a 30-year period from the North and Baltic Sea revealed similar yearly and seasonally case accumulations on the same island in the 1990s as well as several single case events over the whole timespan. All cases except one were caused by flatfish. When flatfish speciation was performed, only common sole was identified. From 1990 to 2019, of all examined harbour porpoises, 0.3% (2/713) from the Baltic Sea and 5.5% (45/820) from the North Sea died due to fish entrapped in the pharynx. On the North Sea coast, the occurrence of fatal obstruction shows high yearly variations from 0 to 33.3%. Years that stand out are especially 1990 to 1992, 1995, as well as 2016. The majority of all cases generally occurred between April and July, indicating also a seasonality of cases. This study evaluates the occurrence of fatal pharyngeal entrapment of fish in two geographically separated harbour porpoise populations. Additionally, common sole is clearly identified as a potentially risky item of prey for these small odontocetes.

International audience; Coastal and estuarine nurseries are composed of habitats with different biotic and abiotic features. Quantifying the contribution of different habitats within nurseries to juvenile fish feeding would help identify those that are essential in the completion of their life cycle, by providing food resources that maximise growth and survival. Essential habitats for four bentho-demersal fish species (whiting, sea bass, plaice and common sole) in an estuarine nursery were identified using gut contents and stable isotopes. Habitats differed in isotopic ratios and benthic communities. The estuarine gradient defined the macrofauna communities and sources of organic matter used by primary consumers. Trophic niche overlaps and trophic contribution of habitats highlighted that the species used both intertidal and subtidal habitats as feeding grounds. Flatfish were local feeders and fed on prey available mainly in the habitat in which they were caught, suggesting feeding behaviour that required little energy for movement. Sea bass were concentrated in upstream habitats, with intertidal mudflats contributing for nearly half of its diet. Whiting had an ubiquitous feeding strategy, suggesting that it may target prey with the most energetic gain in the habitats. Hence, habitats were used simultaneously during the same season or asynchronously throughout the year by the juvenile fish studied, suggesting no preference for a specific habitat at the community scale. Finally, both trophic tracers demonstrated the trophic importance of intertidal mudflats, especially for the sea bass and common sole, with contributions up to the half and two-third of their diet respectively.

The amount of potentially toxic chemicals in a fish depends on various environmental factors, such as temperature and feeding ecology, which can be affected by Global Changes (GC). The main objective of the present work was to study the relative influence of temperature, food quality and food availability on the growth and contamination of juveniles of common sole (Solea solea), a marine flatfish species known to be a relevant indicator of the nursery quality. It focuses on two Persistent Organic Pollutants (CB153 and L -PFOS) of legacy and emerging concern, respectively. To achieve this, we used a toxicokinetic (TK) model in which toxicant flows are mechanistically predicted using a bioenergetic model based on the Dynamic Energy Budget (DEB) theory. This modelling framework was applied to juvenile sole from the Gironde estuary (SW France) and allows accounting for the influence of environmental conditions on fish biological processes involved in toxicant fluxes. To compare their respective influence on model predictions of age, length, and contamination at puberty, we included in a global sensitivity analysis: (1) environmental variability gathered from literature for this particular estuary and (2) TK parameters (i.e. assimilation efficiency AE and elimination rate k ˙ e ) variability and uncertainty gathered from literature about each contaminant but for different fish species and experimental conditions. Then, model predictions were confronted to fish contamination measurements from the Gironde Estuary with different combinations of TK parameter values from literature. Results highlighted a key role of diet composition on fish contamination and growth while water temperature only affected growth. It stressed the need to focus on GC impact on benthic communities and their consequences on juvenile fish diet for future work on GC scenarios. Furthermore, for both chemical, the range of variability of TK parameters from experiments led to underestimated fish contaminations. The best model fits were obtained using TK parameter values from model applications: from Mounier et al. (n.d.) for CB153 (Solea solea, experiment, AE=0.8 and k ˙ e =0 d−1) and from de Vos et al. (2008) for PFOS (food chain of the Western Scheldt estuary, The Netherlands, AE=0.8 and k ˙ e =0.8 10−2.d−1).

Seafood is an important component of the human diet. With depleting fish stocks and increasing prices, seafood is prone to fraudulent substitution. DNA barcoding has illustrated fraudulent substitution of fishes in retail and restaurants. Whether substitution also occurs in other steps of the supply chain remains largely unknown. DNA barcoding relies on public reference databases for species identification, but these can contain incorrect identifications. The creation of a high quality genetic reference database for 42 European commercially important fishes was initiated containing 145 Cytochrome c oxidase subunit I (COI) and 152 Cytochrome b (cytB) sequences. This database was used to identify substitution rates of Atlantic cod (Gadus morhua) and common sole (Solea solea) along the fish supply chain in Belgium using DNA barcoding. Three out of 132 cod samples were substituted, in catering (6%), import (5%) and fishmongers (3%). Seven out of the 41 processed sole samples were substituted, in wholesale (100%), food services (50%), retailers (20%) and catering (8%). Results show that substitution of G. morhua and S. solea is not restricted to restaurants, but occurs in other parts of the supply chain, warranting for more stringent controls along the supply chain to increase transparency and trust among consumers. ispartof: FOOD AND CHEMICAL TOXICOLOGY vol:141 ispartof: location:England status: published

In the present study, the histological-based condition of common sole (Solea solea) larvae in the English Channel was evaluated to assess the relevance of experimentally-calibrated indices for wild collected specimens. Based on topographical observation of foregut, midgut, hindgut, liver and pancreas, each of the 202 larvae analysed was attributed one of the six grades of a condition index that was developed for sole in the nineties. In parallel, a synthetic table of 20 criteria historically used as condition indicators was created from an extensive review of the literature. These criteria were related to tissular integrity, cells height, nuclei, presence of prey and vacuolisation of the same five target organs. For each larva, each criterion was scored on a scale from one to three. Multiple correspondence analyses coupled to clustering and indicator values were used to explore the relationship between the condition index and criteria as well as to highlight which complementary information the latter could provide to the former. Results showed that some adjacent grades were related to the same set of scored criteria, suggesting that these grades are not as distinguishable in the field as they can be in controlled conditions. Some criteria like vacuoles in the enterocytes, size of the hepatocytes, amount of zymogen, stain of acini, presence of prey in the digestive tract and goblet cells in the foregut, were independent of the condition index and depicted more recent food intake than a true condition status. Conversely, criteria related to tissular integrity as well as presence of energetics reserves like vacuoles in the liver appeared more relevant to evaluate the condition status of fish larvae since their increasing scores were associated to different grades. It is concluded that the grading system obtained from experimental observations may not be adapted to reflect the different larval condition states that could be encountered in the field. A simplified grading system, based on three grades and a reduced set of relevant criteria is then proposed.

The high nutritional quality of common sole Solea solea increases its value for the fishery industry and for the aquaculture sector. To ensure the expansion of its production, it is necessary to implement farming and broodstock management technique to produce high quality eggs and larvae. This work summarizes eight years of study on reproductive performances, growth and parental contribution of a common sole broodstock from the Mediterranean-North Adriatic Sea. The broodstock (11 females and 13 males) reached the peak of fecundity after 5/6 years of captivity, with a production of 296.48 and 376.54 × 103 of total eggs kg−1 female with a fertilization rate of 31.6 ± 18.3 and 41.9 ± 23.8 %, respectively. Results shows that variations in temperature cycles are pivotal for a successful breeding season, and body condition during the first 3 years of captivity was the most important parameter positively correlated to parental contribution for both males and females. Parental contribution was assessed by eight species-specific microsatellite loci during the first 3 years of reproduction. Although the two sexes displayed different temporal trends, parentage assessment demonstrated an overall increase in the number of active breeders. However, only 13 couples out of 50 produced the 70.4 % of the larvae in year 5, confirming the same reproduction behavioural pattern in Mediterranean common sole than that observed both in Senegalese sole and in common sole of Atlantic origin. This work provides valuable data needed to understand the mechanisms behind the maturation characteristics of this species and support future strategy for the establishment and management of Mediterranean common sole aquaculture.

Fishery discard survival depends on multiple conditions; caution is essential when survival study outputs are employed to support management decisions. The study presents a stepwise procedure, devised to estimate discard survival, that accounts for the variability characterizing commercial fishing practices. The procedure was applied to the first survival study performed onboard rapido trawlers targeting Solea solea in the Mediterranean Sea. Undersized specimens collected during sorting were assessed for vitality; some were retained for captive observation. The main drivers affecting discard survival at the time of catch sorting (immediate survival) were identified and used to outline four different operational conditions set (scenarios). Immediate survival in each scenario was subsequently modified by applying a hazard coefficient of survival after 5 days of captive observation in relation to each vitality class, thus obtaining relative survival estimates following discarding. Temperature and air exposure duration were found to exert a major effect on survival, with catch weight and seabed type being additional important factors. The relative survival rate showed an aggregate value of 22.9% (10.5–33.4%). Scenario approach can enhance our understanding of the stressors influencing discard survival. The outcomes are discussed to explore the potential applications of the procedure to the identification of mitigation strategies.

The retinas of nonmammalian vertebrates have cone photoreceptor mosaics that are often organized as highly patterned lattice-like distributions. In fishes, the two main lattice-like patterns are composed of double cones and single cones that are either assembled as interdigitized squares or as alternating rows. The functional significance of such orderly patterning is unknown. Here, the cone mosaics in two species of Soleidae flatfishes, the common sole and the Senegalese sole, were characterized and compared to those from other fishes to explore variability in cone patterning and how it may relate to visual function. The cone mosaics of the common sole and the Senegalese sole consisted of single, double, and triple cones in formations that differed from the traditional square mosaic pattern reported for other flatfishes in that no evidence of higher order periodicity was present. Furthermore, mean regularity indices for single and double cones were conspicuously lower than those of other fishes with "typical" square and row mosaics, but comparable to those of goldfish, a species with lattice-like periodicity in its cone mosaic. Opsin transcripts detected by quantitative polymerase chain reaction (sws1, sws2, rh2.3, rh2.4, lws, and rh1) were uniformly expressed across the retina of the common sole but, in the Senegalese sole, sws2, rh2.4, and rh1 were more prevalent in the dorsal retina. Microspectrophotometry revealed five visual pigments in the retina of the common sole [S(472), M(523), M(536), L(559), and rod(511)] corresponding to the repertoire of transcripts quantified except for sws1. Overall, these results indicate a loss of cone mosaic patterning in species that are primarily nocturnal or dwell in low light environments as is the case for the common sole and the Senegalese sole. The corollary is that lattice-like patterning of the cone mosaic may improve visual acuity. Ecological and physiological correlates derived from observations across multiple fish taxa that live in low light environments and do not possess lattice-like cone mosaics are congruent with this claim.

Connectivity between spawning and nursery grounds influences the colonization, replenishment and resilience of populations of marine organisms. Connectivity rate, measured as the exchange of individuals between spawning and nursery grounds, is therefore a crucial determinant of stock size. However, connectivity of early-life stages is hard to explore due to sampling limitations and insufficient knowledge on potential larval sources. Here we present new insights into pre- and post-settlement dispersal of the common sole (Solea solea L.) at a spatial scale of 5–500 km in the Southern North Sea. Patterns at a scale of

Summary This study determined prey consumption in common sole as a function of prey size (0–0.5, 1–1.5, 2–2.5 and 4–5 g), sediment thickness (20 cm and 2 cm) and fish size (50 g, 125 g or 300 g). Prey consumption (in numbers of prey eaten per fish per day) was reduced with increasing prey size and sediment thickness, and was increased with increasing fish size (p

An experiment was conducted to evaluate the use of soybean protein concentrate (SPC) meal as a partial replacement for fishmeal (FM) protein at levels of 0%, 25%, 50%, 75%, and 100% (SPC0, SPC25, SPC50, SPC75, and SPC100 groups, respectively) in weaning diets (~55% crude protein) for post-larvae of common sole (Solea solea). During the weaning period, larvae were fed on the experimental diets simultaneously with the life food for 15 days. After completing the weaning period, post-larvae (5.5 mg) were fed with the experimental diets for further 30 days in triplicates. No significant (P > 0.05) variations were recorded in the growth performance and survival rate up to the 50% SPC level, after which the larvae growth and survival rates were significantly (P

A.L. Primo and F. Martinho are funded by national funds (OE), through FCT (Portuguese Foundation for Science and Technology), I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. A. Vaz is funded by the FCT (Portuguese Foundation for Science) through a PhD grant (SFRH/BD/137862/2018). Financial support was obtained through the project “Mytag - Integrating natural and artificial tags to reconstruct fish migrations and ontogenetic niche shifts” (PTDC/MAR-EST/2098/2014), under the Project 9471 – Reforçar a Investigaçao, ˜ o Desenvolvimento Tecnologico ´ e a Inovaç˜ ao (Projeto 9471-RIDTI) and subsidized by the European Regional Development Fund (FEDER, POCI-01-0145-FEDER-016787) and through the strategic plan of the Centre for Functional Ecology - Science for People and the Planet (CFE) (UIDB/04004/2020), financed by FCT/MCTES through national funds (PIDDAC). Additional support was also obtained via project “RENATURE - Valorization of the Natural Endogenous Resources of the Centro Region” (CENTRO-01-0145-FEDER-000007), funded by the Comissão de Coordenacã̧o da Região Centro (CCDR-C) and subsidized by the European Regional Development Fund (FEDER). We also acknowledge the support from the Integrated Program of SR&TD “SmartBioR” (reference Centro-01-0145-FEDER-000018, cofunded by CENTRO2020/PORTUGAL2020/FEDER). Understanding the causes of variation in recruitment of marine fishes has been a central goal over the last century. However, the relationship between year class strength and larval growth and survival is poorly known for most species. The main goal of this study was to investigate the relationships between larval traits and year class strength of two flatfish species in an nursery estuary. We examined the effects of the variation in the early life characteristics (pelagic larval growth, pelagic larval duration, size-at-hatching and size-at-settlement) on post-settlement survival of flounder Platichthys flesus and common sole Solea solea in the Mondego estuary (Portugal) over a 5-year period (2011–2015). The two flatfish species showed distinct larval traits variation during the study period, mainly related with location of the spawning ground and intrinsic biologic patterns. Flounder was able to delay metamorphosis while gathering energy and/or waiting for suitable environmental cues from estuarine origins while sole take advantage of better environmental conditions due to a later hatching. Early fast growth were strongly related with subsequent growth, affecting larval survival. Both growth and larval traits variation during the studied period were strongly related with temperature. This study highlights the importance of early growth for fish survival and contributes with key information on fish early life stages that will support a better management of fish stocks. info:eu-repo/semantics/publishedVersion

Climate change not only alters ocean physics and chemistry but also affects the biota. Larval dispersal patterns from spawning to nursery grounds and larval survival are driven by hydrodynamic processes and shaped by (a)biotic environmental factors. Therefore, it is important to understand the impacts of increased temperature rise and changes in wind speed and direction on larval drift and survival. We apply a particle-tracking model coupled to a 3D-hydrodynamic model of the English Channel and the North Sea to study the dispersal dynamics of the exploited flatfish (common) sole (Solea solea). We first assess model robustness and interannual variability of larval transport over the period 1995-2011. Then, using a subset of representative years (2003-2011), we investigate the impact of climate change on larval dispersal, connectivity patterns and recruitment at the nursery grounds. The impacts of five scenarios inspired by the 2040 projections of the Intergovernmental Panel on Climate Change are discussed and compared with interannual variability. The results suggest that 33% of the year-to-year recruitment variability is explained at a regional scale and that a 9-year period is sufficient to capture interannual variability in dispersal dynamics. In the scenario involving a temperature increase, early spawning and a wind change, the model predicts that (i) dispersal distance (+70%) and pelagic larval duration (+22%) will increase in response to the reduced temperature (–9%) experienced by early hatched larvae, (ii) larval recruitment at the nursery grounds will increase in some areas (36%) and decrease in others (-58%), and (iii) connectivity will show contrasting changes between areas. At the regional scale, our model predicts considerable changes in larval recruitment (+9%) and connectivity (retention -4% and seeding +37%) due to global change. All of these factors affect the distribution and productivity of sole and therefore the functioning of the demersal ecosystem and fisheries management. This article is protected by copyright. All rights reserved.

In this study, concentrations of heavy metals were determined by ICP-MS in the edible tissues of common sole (Solea solea Linnaeus, 1758), whiting (Merlangius merlangus Linnaeus, 1758), silver sillago (Sillago sihama Forsskal, 1775) and muscle-exoskeleton of green tiger shrimp (Penaeus semisulcatus De Haan, 1844), from the seas of Iskenderun Bay, Eastern Mediterranean, Turkey, in January–February, 2016. The lowest and highest mean concentrations of Mn, Cr, Cd, Ni, Hg, As, Pb, and Co in fish and shrimp’ muscles were found, respectively, as follows: 0.166–0.382, 0.134–0.336, 0.005–0.008, 0.091–0.140, 0.026–0.228, 1.741–29.254, 0.087–0.110, and

This study compares the effect of food type (formulated diet vs. natural food) and fish size on protein and energy utilization efficiencies for growth in common sole, Solea solea (L.). Replicate groups of common sole (mean initial body weight ± SD was 45.7 g ± 2.1 and 111.2 g ± 4.2) received the diets at five (natural feed) or four (formulated diet) feeding levels. The protein utilization efficiency for growth (kgCP) was higher (P > 0.001) in common sole fed ragworms than in common sole fed the formulated diet (respectively, 0.40 and 0.31). Likewise, the energy utilization efficiency for growth (kgGE) was higher (P = 0.001) in common sole fed ragworms than in common sole fed the formulated diet (respectively, 0.57 and 0.33). The protein maintenance requirement was not different between food types (P = 0.64) or fish size (P = 0.41) being on average 0.82 g kg−0.8 day−1. The energy maintenance requirement was not different between food type (P = 0.390) but differed between fish size (P = 0.036). The gross energy maintenance requirement of small common sole was 35 kJ g−0.8 day−1. The gross energy maintenance requirement of large common sole was 25 kJ g−0.8 day−1. In conclusion, the low growth of common sole fed formulated diets was related to reduced feed utilization.

Flatfish have a high market acceptance thus representing a profitable aquaculture production. The main farmed species is the turbot (Scophthalmus maximus) followed by Japanese flounder (Paralichthys olivaceous) and tongue sole (Cynoglossus semilaevis), but other species like Atlantic halibut (Hippoglossus hippoglossus), Senegalese sole (Solea senegalensis) and common sole (Solea solea) also register an important production and are very promising for farming. Important genomic resources are available for most of these species including whole genome sequencing projects, genetic maps and transcriptomes. In this work, we integrate all available genomic information of these species within a common framework, taking as reference the whole assembled genomes of turbot and tongue sole (>210× coverage). New insights related to the genetic basis of productive traits and new data useful to understand the evolutionary origin and diversification of this group were obtained. Despite a general 1:1 chromosome syntenic relationship between species, the comparison of turbot and tongue sole genomes showed huge intrachromosomic reorganizations. The integration of available mapping information supported specific chromosome fusions along flatfish evolution and facilitated the comparison between species of previously reported genetic associations for productive traits. When comparing transcriptomic resources of the six species, a common set of ~2500 othologues and ~150 common miRNAs were identified, and specific sets of putative missing genes were detected in flatfish transcriptomes, likely reflecting their evolutionary diversification.

The present studycompares size selectivity of commercially used hand-woven slack knotted codendand three different alternative (40 mm square mesh, 44 mm and 50 mm diamondmesh) machine woven codends for bogue (Boops boops) and common sole (Soleasolea). Hauls were conducted using covered codend method between 10 October and16 December 2011 in Mersin Bay. Results show that alternative machine wovencodends are selective enough for bogue however, tested four codends are notsufficient in releasing individuals under legal size for common sole., Bu çalışmadaticari el örmesi ve gevşek düğümlü torba ile üç farklı alternatif fabrikasyontorbaların (40 mm karegöz, 44 mm ve 50 mm baklava gözlü) boy seçiciliklerikupes (Boops boops) ve dil balığı (Solea solea) için karşılaştırılmıştır.Çekimler Mersin Körfezi’nde 10 Ocak - 16 Aralık 2011 tarihleri arasında örtütorba yöntemi kullanılarak gerçekleştirilmiştir. Sonuçlar alternatiffabrikasyon torbaların kupes için yeterli seçiciliğe sahip olduğunu bununlaberaber dil balığı için test edilen 4 torbanın da yasal boyun altındakibireyleri kaçırmada yetersiz kaldığını göstermektedir.

© 2018, Springer Nature Switzerland AG. While otolith shape analysis can provide a valuable tool for discriminating between fish populations, factors which may influence otolith shape, such as the effect of size, directional asymmetry in growth, and local environmental conditions, are often unknown. Here, we analyzed differences in otolith shape across three size classes of age-0 common sole Solea solea L. from nursery grounds off the Belgian coast and in the Wadden Sea. Across size classes, form-factor decreased and roundness remained consistently high in both nursery grounds, while ellipticity increased in the Belgian nursery. Directional asymmetry between left and right otoliths measured by Fourier coefficients accounted for 0.96 and 7.2% of the variance when comparing otoliths overall, and for each size class, respectively. Within the Belgian nursery, results were consistent across sampling years and locations. In addition, otolith shape was marginally different between nursery grounds, but highly variable within nursery grounds. A small divergent group, which seems partly related to fish size, was noted at both spatial and temporal scales. Based on these results and before embarking on a study of population structure using otolith shape in age-0 common sole, we recommend testing for directional asymmetry and fish size effects across the entire region of interest. ispartof: HYDROBIOLOGIA vol:845 issue:1 pages:95-108 status: published

The Marmara Sea is a semi closed fishing area in Turkey and has valuable fish species such as the common sole, black scorpionfish and horse mackerel. Domestic waste, generated by the population of over 25 million living in the coastal zone as well as industrial facilities in the region are the main causes of pollution in the Marmara Sea. In the current study, the levels of toxic metals (arsenic, cadmium, mercury, and lead) in samples of three fish tissue were analysed over a year-long period and compared with international results. The health risks for different age groups caused by the consumption of these fish were estimated. The results revealed that regular weekly consumption of sole and horse mackerel caught from the Marmara Sea posed health risks for child and youth populations. These fish species should be consumed more carefully due to potential arsenic-related hazards and carcinogenic risks for vulnerable consumer groups.

Cerim, Hasan/0000-0003-3025-1444 WOS: 000520041400002 In this study, age and sex compositions, length distributions, growth parameters and length-weight relationships of common sole populations were determined in Gulluk Bay, southern Aegean Sea, Turkey. Trammel nets and beach seines which have different full mesh sizes were used to obtain samples. Sex ratio (female:male) was found to be 1.14:1. Growth parameters of the common sole in Gulluk Bay was described as; L-infinity=33.95, K=0.208 y(-1), t(0)=-0.032, L-infinity=31.98, K=0.236 y(-1), t(0)=-0.037 y and L-infinity=29.11, K=0.324 y(-1), t(0)=-0.030 y, for sexes combined, females and males, respectively. Length-weight relationships for combined sexes, females and males were W=0.0079L(3.064), W=0.0072L(3.101) and W=0.0088L(3.024), respectively. Combined individuals and females showed positive allometric growth and males showed isometric growth. Ages ranged between 0-9 years. Study results could be useful for further common sole fishery management strategies. Mugla Sitki Kocman University, Scientific research Project OfficeMugla Sitki Kocman University [BAP 13/119] This study was funded by Mugla Sitki Kocman University, Scientific research Project Office with Phd thesis project number BAP 13/119.

The Baltic Sea provides a classical example of how an environmental gradient is associated with the distribution of marine species. Here, numerous genetic studies have revealed clear patterns of population structuring linked to the physical features of the gradient itself. Nevertheless, it remains difficult to distinguish clearly between the different micro-evolutionary processes that shape these structured populationsin situ. The common sole (Solea solea) is a benthic flatfish that rarely occurs within the Baltic Sea, but that exhibits a clear genetic break between populations from the North Sea – Baltic Sea transition zone and the remainder of the Atlantic Ocean. Here, we aim to evaluate the extent to which natural selection is involved in the observed patterns of divergence of sole populations occurring in the transition zone by comparing them with population structures of other flatfish species that have successfully colonized the Baltic Sea. By using several thousand of ddRAD-derived SNPs, we identified a fine-scale pattern of isolation-by-distance (IBD) of sole populations in the region. However, despite strong biological similarities among the flatfishes compared here, the sole IBD was, by far, the lowest detected across the transition zone. While selection was inferred to strongly influence all other flatfishes evolutionary histories, the analytical inference on the sole demographic history suggests that this fine-scale IBD is mainly maintained by neutral processes due to low effective population size of sole in the transition zone and asymmetrical gene flow. Our work contributes to a growing body of evidence suggesting that the strength of the different micro-evolutionary processes is species-specific, even when species occur in the same environment.

Estuarine ecosystems are particularly impacted by global change and, specifically, bychemical pollution from numerous xenobiotics that may be associated to ecotoxicological and health risks. In environmental toxicology and risk assessment, bioaccumulation is a fundamental process as it controls the internal doses of potential toxicants in organisms. However, the contamination and decontamination flows depend on internal processes thatare themselves dependent on environmental conditions (e.g. temperature, food) and thus on the other variables of global change.In this context, this manuscript aims at describing, within a mechanistic modelling framework, the bioaccumulation processes of two families of potentially toxic and bioaccumulable halogenated persistent organic pollutants (POPs) with contrasting physicochemical properties: the polychlorinated biphenyls (PCBs, highly lipophilic historical compounds) and the perfluorinated substances (PFAS, amphiphilic emerging compounds).This work focuses on the Gironde estuary whose nursery function is fundamental for many species of marine fish including the common sole (Solea solea), often used as an indicator of the quality of coastal and estuarine bursary grounds. In order to account for the influence of environmental conditions on bioaccumulation, the first part of this work consisted in developing a toxicokinetic model (TK) coupled with a mechanistic bioenergetic model based on the theory DEB (Dynamic Energy Budget). This DEBmodel has been parameterized for common sole and calibrated for each sex (packageDEBtool). It allows predicting the main evolution of the physiological functions of interest forbioaccumulation (ingestion, growth, reproduction...) throughout the life cycle of an individualaccounting for dynamic environmental conditions. The developed TK model was first calibrated for some PCBs, under controlled conditions, using an innovative method to take into account individual ingestion variability. This work showed that even if the individual ingestion of each fish is accounted for, the effective assimilation of contaminant is very variable and correlated with the lipid levels of the individuals. The application of the model tothe in situ conditions of the Gironde estuary led to identify that, whatever the contaminant family, the composition of the soles diet had a strong influence on the variability of soles contamination and age at sexual maturity. The comparison of model predictions with measurements made in juveniles of the estuary allowed calibrating the TK parameters values for the major compound of each family in the environment (CB153 and PFOS). This calibration led to two observations in the context of a risk assessment: (1) a lack of knowledge to extrapolate calibrations of TK parameters under controlled conditions to natural conditions;(2) the difference in risk assessment error related to the use of the same "worst case" TK parameters regardless of the compounds. Lastly, simple prospective scenarios have beendeveloped to illustrate these results and the possible applications of the model developed.Ultimately, these predictions of soles contamination, growth and development may be related in future work to potential effects on the physiological functions of sole (DEBtox models), and to consequences on soles population dynamics (e.g. matrix population models).; Les estuaires sont des écosystèmes aquatiques particulièrement soumis au changement global et notamment à la pollution par de nombreux xénobiotiques pouvant présenter un risque écotoxicologique et sanitaire. En toxicologie environnementale et en évaluation des risques la bioaccumulation est un processus fondamental car elle contrôle les doses internes de toxiques potentiels. Or les flux de contamination et de décontamination des organismes dépendent de processus internes (e.g. nutrition, croissance) eux-mêmes dépendant des conditions environnementales (e.g. température, nourriture) qui peuvent être affectées par le changement global.Dans ce contexte, cette thèse se propose de décrire, dans un cadre de modélisation mécaniste, les processus de bioaccumulation de deux familles de polluants organiques persistants (POP) halogénés potentiellement toxiques et bioaccumulables, aux propriétés physico-chimiques contrastées : les polychlorobiphényles (PCB, composés historiques fortement lipophiles) et les substances perfluorées (PFAS, composés émergents amphiphiles). Ce travail se focalise sur l’estuaire de la Gironde dont la fonction de nourricerie est fondamentale pour de nombreuses espèces de poissons marins dont la sole commune (Solea solea), souvent utilisée comme indicatrice de la qualité des nourriceries côtières et estuariennes.Pour permettre de tenir compte des fluctuations des conditions environnementales sur la bioaccumulation, dans la première partie de ce travail, j’ai développé un modèle de toxicocinétique(TK) couplé avec un modèle mécaniste bioénergétique basé sur la théorie DEB (Dynamic Energy Budget). Ce modèle DEB a été paramétré pour la sole commune et calibré pour chaque sexe (package DEB tool). Il permet de prédire les principales évolutions des fonctions physiologiques d’intérêt en bioaccumulation (ingestion, croissance, reproduction...), tout au long du cycle de vie d’un individu, en fonction de conditions environnementales dynamiques. Le modèle TK développé a été complexifié par l’ajout d’un flux d’élimination de contaminants, non considéré dans les précédents modèles DEB-TK.La calibration des paramètres toxicocinétiques (TK) du modèle, pour 4 congénères de PCB, est basée sur une méthode innovante de prise en compte de la variabilité individuelle d’ingestion, appliquée à une expérimentation de contamination de juvéniles de sole via leur nourriture. Ce travail a montré que même en tenant compte de l’ingestion de chaque poisson, l’assimilation efficace de contaminant était très variable et corrélée aux taux de lipides des individus. Dans une seconde partie, ce modèle a été appliqué aux conditions in situ de l’estuaire de la Gironde. Il a permis de mettre en évidence la forte influence de la composition du régime alimentaire sur la variabilité de l’âge à la maturité sexuelle et de la contamination des soles pour les deux familles de contaminant étudiées. La confrontation des prédictions du modèle aux mesures de contaminants dans les juvéniles de sole de l’estuaire a permis de calibrer les paramètres TK du composé majeur de chaque famille dans l’environnement (CB153 et PFOS). Cette calibration a conduit à deux constats dans le cadre de l’évaluation du risque : (1) un manque de connaissances pour extrapoler les calibrations de paramètres TK en conditions contrôlées vers les conditions naturelles ; (2) la différence d’erreur d’évaluation du risque liée à l’utilisation des mêmes paramètres TK «les plus pessimistes » quels que soient les composés. Enfin, des scenarios prospectifs simples ont été développés pour illustrer ces résultats et les possibles applications du modèle développé.In fine, ces prédictions de la contamination, de la croissance et du développement des soles pourront être reliées, lors de travaux ultérieurs, à des effets potentiels sur les fonctions physiologiques de la sole (modèles DEBtox), et aux conséquences sur la dynamique des populations de soles (e.g.modèles matriciels de population).

The management of coastal fisheries and coastal marine areas both require information on the use and importance of coastal marine habitats for marine species. This information is certainly pertinent for exploited species dependent on these coastal habitats for specific life-history stages. This study uses two different measures of habitat suitability to build Habitat Association Models (HAMs) and Habitat Growth Models (HGMs) for juveniles of three commercially and recreationally important fish species (Pleuronectes platessa, Platichthys flesus, and Solea solea) of the Inner Danish Waters (IDW). A large scale, one-off juvenile survey was used to collect juvenile fish and directly observed environmental data. The survey informed Generalised Linear (Mixed) Models (GLMs and GLMMs), which were fit and run through repeated random sub-sampling cross-validation before being utilised to build interpolative maps of both prediction and model uncertainty. The limitations of this approach are discussed in reference to the future works required to complement and improve such static habitat suitability maps. These results can be used to inform marine spatial planning and future work into the role of juvenile habitats in supporting fishery species.

Common sole (Solea solea) aquaculture production is based mostly on wild-caught breeders. Recently, the successful reproduction of first-generation fish that were reared in captivity was accomplished. A consistent good quality and quantity of produced eggs throughout the year, and of next-generation broodstock, is important for reducing the overall cost of production.Hoxgenes play a pivotal role in normal embryonic development and alterations of their temporal expression level may be important for egg viability. Expression profile analysis of fivehoxgenes (hoxa1a,hoxa2a,hoxa2b,hoxb1aandhoxb1b) involved in early embryonic development and ofhoxa13a, which is involved in late stages, was carried out. Results revealed a premature and/or maternal expression ofhoxa13ain sole embryos, and the detection ofhoxa2aandhoxa2bgenes as members of paralog group 2. Principal Component Analysis ofhoxgene expression in 54 ± 6 hours post fertilization embryos coming from wild-caught broodstock and a first-generation one reared in the hatchery, unveiled that these broodstocks are clearly distinct. In addition, their pairwise comparison revealed significant differences in the expression levels ofhoxb1aandhoxb1bgenes.Hoxgene regulation during embryonic development could give valuable insight into rearing sole broodstocks with different origin in concert, and also into gaining a steady mass production of eggs, either in quality or quantity, all year round.

Estuarine ecosystems are particularly impacted by global change and, specifically, bychemical pollution from numerous xenobiotics that may be associated to ecotoxicological and health risks. In environmental toxicology and risk assessment, bioaccumulation is a fundamental process as it controls the internal doses of potential toxicants in organisms. However, the contamination and decontamination flows depend on internal processes thatare themselves dependent on environmental conditions (e.g. temperature, food) and thus on the other variables of global change.In this context, this manuscript aims at describing, within a mechanistic modelling framework, the bioaccumulation processes of two families of potentially toxic and bioaccumulable halogenated persistent organic pollutants (POPs) with contrasting physicochemical properties: the polychlorinated biphenyls (PCBs, highly lipophilic historical compounds) and the perfluorinated substances (PFAS, amphiphilic emerging compounds).This work focuses on the Gironde estuary whose nursery function is fundamental for many species of marine fish including the common sole (Solea solea), often used as an indicator of the quality of coastal and estuarine bursary grounds. In order to account for the influence of environmental conditions on bioaccumulation, the first part of this work consisted in developing a toxicokinetic model (TK) coupled with a mechanistic bioenergetic model based on the theory DEB (Dynamic Energy Budget). This DEBmodel has been parameterized for common sole and calibrated for each sex (packageDEBtool). It allows predicting the main evolution of the physiological functions of interest forbioaccumulation (ingestion, growth, reproduction...) throughout the life cycle of an individualaccounting for dynamic environmental conditions. The developed TK model was first calibrated for some PCBs, under controlled conditions, using an innovative method to take into account individual ingestion variability. This work showed that even if the individual ingestion of each fish is accounted for, the effective assimilation of contaminant is very variable and correlated with the lipid levels of the individuals. The application of the model tothe in situ conditions of the Gironde estuary led to identify that, whatever the contaminant family, the composition of the soles diet had a strong influence on the variability of soles contamination and age at sexual maturity. The comparison of model predictions with measurements made in juveniles of the estuary allowed calibrating the TK parameters values for the major compound of each family in the environment (CB153 and PFOS). This calibration led to two observations in the context of a risk assessment: (1) a lack of knowledge to extrapolate calibrations of TK parameters under controlled conditions to natural conditions;(2) the difference in risk assessment error related to the use of the same "worst case" TK parameters regardless of the compounds. Lastly, simple prospective scenarios have beendeveloped to illustrate these results and the possible applications of the model developed.Ultimately, these predictions of soles contamination, growth and development may be related in future work to potential effects on the physiological functions of sole (DEBtox models), and to consequences on soles population dynamics (e.g. matrix population models)., Les estuaires sont des écosystèmes aquatiques particulièrement soumis au changement global et notamment à la pollution par de nombreux xénobiotiques pouvant présenter un risque écotoxicologique et sanitaire. En toxicologie environnementale et en évaluation des risques la bioaccumulation est un processus fondamental car elle contrôle les doses internes de toxiques potentiels. Or les flux de contamination et de décontamination des organismes dépendent de processus internes (e.g. nutrition, croissance) eux-mêmes dépendant des conditions environnementales (e.g. température, nourriture) qui peuvent être affectées par le changement global.Dans ce contexte, cette thèse se propose de décrire, dans un cadre de modélisation mécaniste, les processus de bioaccumulation de deux familles de polluants organiques persistants (POP) halogénés potentiellement toxiques et bioaccumulables, aux propriétés physico-chimiques contrastées : les polychlorobiphényles (PCB, composés historiques fortement lipophiles) et les substances perfluorées (PFAS, composés émergents amphiphiles). Ce travail se focalise sur l’estuaire de la Gironde dont la fonction de nourricerie est fondamentale pour de nombreuses espèces de poissons marins dont la sole commune (Solea solea), souvent utilisée comme indicatrice de la qualité des nourriceries côtières et estuariennes.Pour permettre de tenir compte des fluctuations des conditions environnementales sur la bioaccumulation, dans la première partie de ce travail, j’ai développé un modèle de toxicocinétique(TK) couplé avec un modèle mécaniste bioénergétique basé sur la théorie DEB (Dynamic Energy Budget). Ce modèle DEB a été paramétré pour la sole commune et calibré pour chaque sexe (package DEB tool). Il permet de prédire les principales évolutions des fonctions physiologiques d’intérêt en bioaccumulation (ingestion, croissance, reproduction...), tout au long du cycle de vie d’un individu, en fonction de conditions environnementales dynamiques. Le modèle TK développé a été complexifié par l’ajout d’un flux d’élimination de contaminants, non considéré dans les précédents modèles DEB-TK.La calibration des paramètres toxicocinétiques (TK) du modèle, pour 4 congénères de PCB, est basée sur une méthode innovante de prise en compte de la variabilité individuelle d’ingestion, appliquée à une expérimentation de contamination de juvéniles de sole via leur nourriture. Ce travail a montré que même en tenant compte de l’ingestion de chaque poisson, l’assimilation efficace de contaminant était très variable et corrélée aux taux de lipides des individus. Dans une seconde partie, ce modèle a été appliqué aux conditions in situ de l’estuaire de la Gironde. Il a permis de mettre en évidence la forte influence de la composition du régime alimentaire sur la variabilité de l’âge à la maturité sexuelle et de la contamination des soles pour les deux familles de contaminant étudiées. La confrontation des prédictions du modèle aux mesures de contaminants dans les juvéniles de sole de l’estuaire a permis de calibrer les paramètres TK du composé majeur de chaque famille dans l’environnement (CB153 et PFOS). Cette calibration a conduit à deux constats dans le cadre de l’évaluation du risque : (1) un manque de connaissances pour extrapoler les calibrations de paramètres TK en conditions contrôlées vers les conditions naturelles ; (2) la différence d’erreur d’évaluation du risque liée à l’utilisation des mêmes paramètres TK «les plus pessimistes » quels que soient les composés. Enfin, des scenarios prospectifs simples ont été développés pour illustrer ces résultats et les possibles applications du modèle développé.In fine, ces prédictions de la contamination, de la croissance et du développement des soles pourront être reliées, lors de travaux ultérieurs, à des effets potentiels sur les fonctions physiologiques de la sole (modèles DEBtox), et aux conséquences sur la dynamique des populations de soles (e.g.modèles matriciels de population).

European seabass and common sole are commercially important species for worldwide fisheries. A European sea bass, Dicentrarchus labrax, specimen (TL 45.3 cm and W 1203.21 g) and a common sole, Solea solea, (TL 26.2 cm and W 180.52 g) were caught off the coast of Boğaziçi, located in Güllük Bay, Muğla, Turkey by a trammel net in December 2013 and in October 2015, respectively. In European sea bass inside the abdominal cavity, abnormally, both new and unabsorbed gonad tissues were observed, together. Although unabsorbed gonad had a membrane, it was surrounded by a new membrane. Unabsorbed and dark colored gonads were found atrophic and new gonad membrane were coated old gonad tissue and egg production were found in normal. In common sole, when the ovaries should be placed in eyeless and eyed side, eyeless side of ovary was in eyed side of abdominal cavity. In this case, it was found that there was no side-separation in ovaries. Industrial and domestic pollution may cause serious environmental problems which are closely related to anomalies in aquatic organisms. On the other hand, genetic characteristics of organisms may be another factor of this kind of abnormalities.

International audience; An accurate representation of the spatial structure of marine fish populations is a prerequisite for unbiased stock assessment, to build appropriate management measures. The common sole (Solea solea, L.) of the Eastern English Channel (EEC) is a commercial flatfish species, whose stock is currently assessed as a single homogeneous population and has been overexploited over the last decade. Previous studies have highlighted the stock's low connectivity and the lack of understanding in sub-adults and adults mixing between putative subunits, raising the issue of a potential spatial structure of this stock. Here, we examined evidence of spatial structure by analyzing spatiotemporal patterns of length and density-at-age using time series (1989–2015) obtained from a scientific survey (UK-BTS). We tested for various hypotheses of spatial structure, based on both scientific and expert knowledge, including three isolated subunits, their combination, and no spatial structure. We combined two sets of analyses: (1) a selection of the von Bertalanffy growth model with spatial effects capturing the most accurate spatial structure of the stock and the analysis of long-term spatial patterns (gradients, trends, synchrony) in growth parameters; and (2) an analysis of the synchrony among density-at-age time series between spatial subunits. Growth analysis revealed a spatial structure in three subunits (i.e. the southwestern, northeastern and English parts of the EEC) and an overall decline of length-at-age, suggesting Fishery-Induced Evolution. The synchrony analysis revealed high spatiotemporal integrity at the level of the southwestern subunit of the EEC. Our two analyses thus detected a lasting signal of spatial stock structure with a probable isolation of the southwestern subunit from the rest of the EEC. Future research should build on our study by investigating the connectivity of sole throughout its entire life cycle, to improve stock assessment and fishery management.; Une représentation exacte de la structure spatiale des populations de poissons de mer est une condition préalable à une évaluation impartiale des stocks, afin d'élaborer des mesures de gestion appropriées. La sole commune (Solea solea, L.) de la Manche orientale (CEE) est une espèce commerciale de poisson plat, dont le stock est actuellement évalué comme une seule population homogène et a été surexploité au cours de la dernière décennie. Des études antérieures ont mis en évidence la faible connectivité du stock et le manque de compréhension chez les sous-adultes et les adultes se mélangeant entre sous-unités putatives, ce qui soulève la question d'une structure spatiale potentielle de ce stock. Nous avons examiné ici les preuves de la structure spatiale en analysant les tendances spatio-temporelles de la longueur et de la densité selon l'âge à l'aide de séries chronologiques (1989-2015) obtenues à partir d'une enquête scientifique (UK-BTS). Nous avons vérifié diverses hypothèses de structure spatiale, fondées sur des connaissances scientifiques et spécialisées, y compris trois sous-unités isolées, leur combinaison et l'absence de structure spatiale. Nous avons combiné deux ensembles d'analyses : (1) une sélection du modèle de croissance de von Bertalanffy avec des effets spatiaux capturant la structure spatiale la plus précise du stock et l'analyse des modèles spatiaux à long terme (gradients, tendances, synchronie) des paramètres de croissance ; et (2) une analyse de la synchronisation entre les séries temporelles de densité à âge entre sous-unités spatiales. L'analyse de la croissance a révélé une structure spatiale dans trois sous-unités (c'est-à-dire les parties sud-ouest, nord-est et anglaise de la CEE) et un déclin global de la longueur selon l'âge, ce qui suggère une évolution induite par la pêche. L'analyse synchrone a révélé une grande intégrité spatio-temporelle au niveau de la sous-unité sud-ouest de la CEE. Nos deux analyses ont ainsi détecté un signal durable de la structure spatiale du stock avec un isolement probable de la sous-unité sud-ouest du reste de la CEE. Les recherches futures devraient s'appuyer sur notre étude en étudiant la connectivité de la sole tout au long de son cycle de vie, afin d'améliorer l'évaluation des stocks et la gestion des pêches.

In the eastern part of the English Channel, common sole (Solea solea) has strong interests in fisheries research. Low recruitment along with a decline in spawning stock biomass have been observed for several years. According to the recruitment hypotheses, larval survival may play an important role that needs to be considered. The fish larval condition can be assessed using histology which has been recognised as the most appropriate method to provide a reliable index of the nutritional status. Based on this approach, this study aimed to identify critical periods of wild-collected sole larvae and to determine sources of variations of their condition between two periods separated by more than 20 years. In line with other studies, the transition from endogenous to exogenous feeding was identified as the most critical period with the lowest proportion of healthy larvae observed. During this first feeding stage, good larval conditions were located in sampling stations close to the coast and at the end of the spring season, in relation to higher temperature and fluorescence values. This highlights the need for sole larvae survival to cross the coastal front, which splits the central and coastal waters, to reach more stable and productive areas. This coastal migration pattern was consistent between 1995 and 2017, with however significantly lower larval abundances in the recent period. Multivariate analyses showed that the spring environmental conditions of 1995, characterised with lower temperature and higher fluorescence values were more favourable to larval condition, compared to the spring in 2017. Areas providing suitable environmental conditions in 2017 were more restricted and limited to sampling stations in front of estuaries. Since small differences in larval survival can lead to large fluctuations in recruitment, the larval condition should be studied in a more long-term approach. This would provide a better understanding of the environmental influence on larval survival and recruitment success.

International audience; The sustainable exploitation of sea resources is based on the understanding of population distribution, structure and functioning. The mismatch between stock units and fish populations can dramatically bias the assessment and lead to irrelevant or even detrimental management measures. The common sole of the Eastern English Channel (EEC; ICES division VIId) is a flatfish species of high interest that has been overexploited over the last decades. Low connectivity induced by early life stages across the stock was previously known, but gaps remained regarding the role of adults in population connectivity and spatial structure. In this study we have filled these gaps by (1) gathering all the information on stock identity through five population- and individual-based approaches, and (2) combining this information in a semi-quantitative framework, i.e. the Stock Differentiation Index (SDI). Regarding the population-based approaches, growth and abundance-at-age analyses highlighted a lasting signal of population structure, with three population subunits. Regarding the individual-based approaches, genetic analysis highlighted low but significant genetic differentiation between the three subunits over an evolutionary time scale. Besides, a mark-recapture study demonstrated a low level of exchange between these subunits. Finally, an analysis of otolith shape pinpointed spatial variation between the three subunits. Overall, the SDI = 0.93 suggested evidence of spatial structure. The misalignment of the current stock definition with the underlying biological metapopulation now requires the improvement of the assessment-management to ensure its sustainable exploitation.

Bu calisma, Turkiye’nin onemli av sahalarindan birisi olan Gulluk Korfezi’nde kullanilan dil fanyali uzatma aglarinin secicilik parametrelerinin tespit edilmesini amaclamistir. Orneklemeler, ag goz boyu 80 ve 90 mm olan fanyali dil aglari ile Kasim 2013 - Aralik 2015 tarihleri arasinda gerceklestirilmistir. Calisma suresince toplam 1209 adet birey yakalanmistir. Secicilik parametrelerinin belirlenmesinde SELECT yontemi kullanilmistir. Kullanilan fanyali ag verileri icin en iyi uyumu bi-modal model vermistir. Bi-modal modele gore optimum yakalama boylari 80 ve 90 mm’lik aglar icin sirasi ile 23,20 ve 27,02 cm olarak bulunmustur. Ayrica 80 ve 90 mm ag goz boyuna sahip dil uzatma aglarina ait ilk yakalama boylari (Lc) sirasi ile 20,37 ve 24,11 cm ve birim cabadaki av miktari (CPUE) 2,94 ve 1,43 kg/1000m olarak hesaplanmistir. CPUE degerlerinden de anlasilacagi gibi av baskisi buyuk boylu bireyleri etkilemektedir. Bu durum, ureyen stok biyokutlesinin her yil azalmasi ve ayrica dogal ve balikciliktan kaynaklanan olumler de dusunuldugunde neslin devamini saglayacak kucuk boylu bireylerin gelecek donemlerde cok az sayida olacagi anlamina gelmektedir. Ticari avciligi duzenleyen tebligde dil baligi icin asgari boy siniri 20 cm’dir. Ilk yakalama boyunun bu sinira cok yakin olmasi nedeni ile ag goz boylarinin duzenlenmesine ihtiyac duyulmamistir. Ancak kullanilan ag posta sayilarinda ciddi duzenlemeler yapilmalidir.