A survey of zoonotic nematodes of commercial key fish species from major European fishing grounds—Introducing the FP7 PARASITE exposure assessment study

High prevalence of Ichthyophonus sp. infections in Northeast Atlantic mackerel (Scomber scombrus).

Marine protected areas in the sampling sites have been established 8-13 years ago. This study was conducted to have a baseline information on the diversity, density and biomass of coral reef fishes inside and outside the five marine protected areas (MPAs) of Casay, Argao; Cawayan, Dalaguete; Daan-Lungsod Guiwang, Alcoy; North Granada, Boljoon and Sta. Cruz, Ronda (Control). Coral reef fishes in the MPAs were identified using Fish Visual Census Method. Results of the t-test showed that the mean diversity (fish species/250m2) of target and non-target fish species found in areas inside and outside the MPAs were significantly different. In terms of target species, the inside and outside density showed no significant difference. Similarly, density (ind./1,000m2) of non-target species inside and outside also showed no significant difference. This is an indication that fish density inside and outside the MPAs were more or less of the same condition. The mean biomass (kg/1,000m2) of target species inside and outside the MPAs showed a significant difference in contrast with non-target species inside and outside the MPAs which showed a no significant difference. Higher biomass of target fish species belonging to family Caesonidae (fusiliers) and Scaridae (parrotfishes) were commonly observed inside the MPAs. Results showed that fish species were more diverse with higher density and biomass inside the MPAs than the outside area. However, fish diversity and density were contributed mostly by non-target species. Hence, the need for a long-term protection and a well-managed MPA to improve fish population in terms of diversity, density and biomass specifically, target fish species.

The four major Chinese carp (MC), Schizothorax fish species (SF), and Cobitidae fish species (CF) are the most important target fish species in China. The swimming behaviour study of three target fish groups is the key to Chinese fishway designs. The 20 min critical swimming speed (Ucrit-20 min) and endurance of the target fish species in relation to body length, swimming speed, and water temperature were estimated using multiple linear regression. The results indicated that both fish body length and water temperature had a significant effect on swimming capability. Performance comparisons indicated that SF were remarkably strong swimmer. CF possess slightly greater swimming capability than MC. The entrance velocity of the upstream fishway should be greater than Ucrit-20 min, but less than maximum swimming speed to make the flow out of the fishway noticeable. The maximum swimming distance could be estimated using endurance model at flow velocity of 1.2 m·s–1. For the downstream-migrating juvenile fish, it was suggested that the flow velocity of turbine intake should be less than maximum sustained speed avoiding entering turbine.

近几年我国水电站过鱼设施设计已将过鱼对象游泳能力作为重要参考. 以我国8个水电站主要过鱼对象为研究目标，在野外实验设施条件下测试了15种鱼(四大家鱼组、裂腹鱼组和鳅组)的感应流速和爆发游泳速度. 采用多元线性回归法分别分析了各组鱼体长及水温对游泳能力的影响，并构建了优化的游泳能力预测模型. 结果表明，四大家鱼组、裂腹鱼组和鳅组的感应流速和爆发游速皆与体长呈负相关，感应流速与水温也皆呈负相关关系. 水温升高使四大家鱼组和裂腹鱼组的爆发游速能力增强，而水温对鳅组鱼的爆发游速影响不大，可能与鳅科鱼类特殊的腹部吸附行为有关. 利用绘制的鱼感应水流和爆发未疲劳的数量百分比的生存曲线进行上行及下行过鱼设施流速设计. 结果表明：当鱼感应水流的数量百分比为90 % 时，四大家鱼、裂腹鱼和鳅组幼鱼感应流速分别为3.00、1.67和3.22 BL/s，裂腹鱼和鳅组成鱼感应流速分别为1.27和2.09 BL/s；当鱼爆发未疲劳的数量百分比为90 % 时，四大家鱼、裂腹鱼和鳅组幼鱼爆发游泳速度分别为8.13、9.27和9.61 BL/s，裂腹鱼和鳅组成鱼爆发游泳速度分别为7.64和7.77 BL/s. 当以裂腹鱼或鳅成鱼为主要过鱼对象时，上行过鱼设施内流速范围建议为1.27~7.64和2.09~7.77 BL/s. 当以四大家鱼、裂腹鱼或鳅幼鱼为主要过鱼对象时，下行过鱼设施入口流速建议小于8.13、9.27和9.61 BL/s. 本研究结果可为我国水电站主要过鱼对象的过鱼设施设计提供参考依据.;In recent years, the design of fish passage has taken the swimming capacity of target fish as an important criterion. Fifteen fish species from eight hydropower stations in China, including the four major Chinese carp, Schizothorax and Cobitidae, were selected as target species. Swimming capability was assessed by measuring induced flow velocity (U_ind) and burst swimming speed (U_burst) under identical test conditions. The relationship between U_ind (or U_burst), water temperature (T) and body length (BL) was assessed using multiple linear regression models and the optimal prediction model of swimming capability was constructed. U_ind and U_burst were negatively related to body length, while temperature effect between U_ind and U_burst varied between the three target fish species: U_ind was negatively related to temperature; U_burst was increased with the temperature for the four major Chinese carp and Schizothorax, while the temperature had little effect on U_burst of Cobitidae, which may be related to the special abdominal adsorption behavior of this fish. The percentage of fish either induced to swim (U_ind) or that were not exhausted (U_burst) was plot using survival curves, which was used to set fish passage design criteria. The result showed that 90 % of fish induced to swim were 3.00 BL/s for juvenile four major Chinese carp, 1.67 and 1.27 BL/s for juvenile and adult Schizothorax, 3.22 and 2.09 BL/s for juvenile and adult Cobitidae, respectively. The 90 % of fish were not exhausted were 8.13 BL/s for juvenile four major Chinese carp, 9.27 and 7.64 BL/s for juvenile and adult Schizothorax, 9.61 and 7.77 BL/s for juvenile and adult Cobitidae, respectively. The recommended pool velocity range of fish passage for upper migration was 1.27-7.64 BL/s for adult Schizothorax and 2.09-7.77 BL/s for adult Cobitidae, respectively. The inlet velocity of fish passage for downstream migration was recommended to be less than 8.13, 9.27 and 9.61 BL/s for juvenile four major Chinese carp, juvenile Schizothorax and juvenile Cobitidae, respectively. The results are helpful for the design of fish passage for the main target fish of hydropower stations in China.

The increased human activities resulting from industrialization and urbanization around the Ondo section of the coastal waters of the Atlantic Ocean have significantly affected the environment. To this end, the water quality, fish abundance and target status of fish species were identified, not-withstanding the influence of human activities on the water quality and its effects on fish abundance. Four fishing communities were purposively selected based on geographical location and accessibility along the coast; Ayetoro and Idi-Ogba communities on the eastern side and Eruna-Ero and Igbokoda on the western side. A total of 120 structured questionnaires were randomly administered using snowball technique at 30 per site. Erunna-Ero community measured the highest mean temperature, dissolved oxygen, salinity and conductivity with 29.39 0.30 oC, 4.48 0.06 mg/L,10.68 0.39ppt and 40.70 0.18 S/cmrespectively, while pH was highest in Idi-Ogba community (6.47 0.00). A total of 61.67% were within 21-40 age brackets; 69.17% were males, and 75% of the males engaged in fishing activities. Agricultural activities were high (97%) with most wastes emptying into the river (85.83%). A total of 27,622 fish individuals were identified across the fishing communities with Igbokoda having the highest abundance (38.13%) and Cynoglossus browni (75.18%) was the highest fish species. In the past, three (3) economically important fish species were of major target but a reduction to two (2) species was observed at the time of study which indicated a reduction in target fish species in Igbokoda community. An increase from three (3) to four (4) target species were observed in Ayetoro, Erunna-Ero, and Idi-ogba communities which indicated an increase in target fish species. The study showed the activities around the coastal water dictated the abundance of fish species and therefore essential to monitor the water quality parameters for the sustainability of fish species in the coastal water.

Changes in histamine (Him), cadaverine (Cad), putrescine (Put), agmantine (Agm) and volatile basic nitrogen (VBN) contents were examined in sardine, Atlantic horse mackerel, chub mackerel and Atlantic mackerel, during ice storage and storage at room temperature. Him formation as well as other amines varied greatly with species of fish and storage conditions. The levels of Him, Cad, Put and VBN increased gradually in all the fish species as decomposition progressed, regardless of storage temperatures. In iced fish, amine production was considerably reduced and Him concentration was, in general, lower than 100 mg/Kg. During ice storage amines increased slowly until day 7, after which a significant rise was detected. In comparison with the other fish species higher levels of Him, Cad and Put were determined in Atlantic mackerel. At room temperature Him, Cad and Put were produced at the highest concentrations in chub mackerel, followed by sardine, Atlantic mackerel and Atlantic horse mackerel. Him concentration maximum exceeded allowable limits for human consumption in the first three species after 24h of storage at room temperature. No correlation was observed for Him or other amine levels and the degree of fish decomposition. Thus, the use of Him or other amines as a freshness index of the studied fish species was not considered appropriate.

UV-press method versus artificial digestion method to detect Anisakidae L3 in fish fillets: Comparative study and suitability for the industry

Seafood is known for its valuable and healthy nutrients; however scientific studies demonstrated the unavoidable presence of contaminants in fish and shellfish. Authorities strongly recommend fish consumption, especially to sensible groups of population (pregnant or nursing women, infants and children), and ask the scientific community for novel and coherent data to establish clear guidelines for consumers. There is also a serious need to extend the monitoring to emerging chemical pollutants, other than methylmercury, dioxins and polychlorinated biphenyls, to better understand the level of seafood contamination.
\nAn innovative UHPLC-MS/MS method for the quantification of glycine betaine (GB) in Tapes philippinarum was developed and validated, taking the 2002/657 European Decision as guideline; GB is an endogenous osmolyte abundant in molluscs, and represent a vital methylating agent in humans. 
\nMoreover, a previously developed and validated UHPLC-MS/MS method was used to conduct a preliminary monitoring of the presence of the two main perfluorinated contaminants, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), in six fish species from Italian markets (Dicentrarchus labrax, Merluccius merluccius, Mugil cephalus, Pleuronectes platessa, Scomber scombrus and Sparus aurata). The daily contribution of seafood to PFOS and PFOA dietary intake in Italian population was calculated and data were compared to the corresponding Tolerable Daily Intakes established by EFSA in 2008. 
\nResults revealed that the risk of contamination related to fish consumption is unlikely, but suggested the need to conduct further surveys focused on certain species from different sampling site. Subsequently, a mono-specie monitoring was carried out in 140 farmed and wild subjects of Dicentrarchus labrax, from 14 different locations in the Mediterranean area. The obtained results showed that wild subjects are sensibly more contaminated than farmed ones, and that levels of fish contamination are strongly influenced by their geographical origin and the proximity to polluted areas.

Anisakis simplex sensu stricto is a parasite infecting several commercial fish species in the Northeast (NE) Atlantic, known to be the aetiological agent of the human zoonosis anisakiasis. The present study investigated the response of A. simplex (s. s.) third stage larvae (identified to species level by mtDNA cox2 sequencing) to the storage time and temperature of Atlantic herring (Clupea harengus), Atlantic mackerel (Scomber scombrus) and blue whiting (Micromesistius poutassou) from NE Atlantic fishing areas. A total of 300 fish per species were divided in batches of 50 individuals straight after catch. Each batch was stored at different temperature conditions (2 °C, 5 °C, 15 °C) for different time intervals (24h and 48h). A batch of 50 fish of each species was frozen immediately after catch and used as control (time zero). All fish were inspected by the UV-press method. Blue whiting was the most infected fish species while mackerel harboured the highest proportion of intra-vitam A. simplex (s. s.) larvae in the musculature. In blue withing there was a significant increase in the proportion of larvae in the muscle with increasing storage temperatures (5 °C < 15 °C) and time (24h < 48h). Herring showed a weak trend of increasing parasite infection in the muscle with increasing temperature/time. In contrast, no significant differences of muscle/viscera larval distribution were observed between batches of mackerel stored at different temperatures for different time intervals. Storage temperature and time seem to play a role in the post-mortem motility of A. simplex (s. s.) larvae in herring and blue whiting. Keeping the temperature at ≤ 2 °C seems to prevent post-mortem larval migration into the flesh during fish storage, handling, and transport. Besides abiotic variables, the differences observed in larval post-mortem motility in the different fish species are biologically determined, and attributable to species-specific host-parasite interactions.

This study analysed commercial ‘Srdelara’ purse seine landings in the Central Eastern Adriatic from November 2020 to March 2022. The observed commercial landings demonstrated typical seasonal variations, with a peak from September to November and the lowest landings recorded from spring to early summer. Sardines dominated the purse seine landings, comprising 97.9% of the total landing, followed by anchovies at 1.3%, with occasional by-catches or other species. Biological analysis involved collecting samples of eight pelagic fish species (sardine, anchovy, round sardinella, Atlantic bonito, Atlantic horse mackerel, Atlantic mackerel, chub mackerel and bogue) captured by the aforementioned fishing gear during the study period. The length frequency distributions of the investigated fish species were predominantly unimodal, with the exception of the Atlantic horse mackerel. Moreover, the length–weight relationships indicated isometric growth for each examined species. Stable isotope analysis revealed overlapping isotopic niches among the eight analysed fish species, with estimated mean trophic positions ranging from 3.0 to 4.7, indicating consumption of prey across approximately two trophic levels. The round sardinella and bogue had the smallest isotopic niche, while Atlantic mackerel had the widest one. This study highlights the need for further research to evaluate the observed overlap among pelagic species, particularly between small and medium-sized pelagic fish, as this interaction could significantly impact their biomass. Determining the extent of this overlap is crucial for improving management strategies and ensuring the sustainability of pelagic fish stocks in the Adriatic Sea.

Scoring the parasite risk in highly-valuable fish species from southern ICES areas

Changes in fish habitat induced by dam construction in the downstream river have been well documented in an increasing body of literature. Fish habitats in the backwater zone of dams have undergone dramatic changes, which have still remained poorly understood. This study aims to provide a more complete understanding of fish habitat distribution and clarify fish habitat utilization patterns in the upstream dam in order to adopt effective remediation activities. This study was conducted in the Three Gorges Dam (TGD) as it is the world's largest installed capacity hydropower station, with a backwater zone length of about 660 km. Four major Chinese carp (FMCC) were selected as target fish species, and fish habitat distribution upstream of TGD was assessed by integrating the swimming ability and environmental preference of different fish species into their critical life stages. Assessment results at different life stages of the target fish species showed that June was a critical period for spawning activities FMCC in the fluctuating backwater zone of TGD. The riverbank was an important feeding habitat for FMCC, and the high‐velocity flow in the centre of the channel exceeded the limits of the swimming ability of target fish. The fish habitat distribution in the fluctuating backwater zone of TGD was heavily affected by runoff from April to September and by dam operation from October to March of the next year. This work provide valuable information about river conservation and management in the upstream of TGD.

This study presents a large-scale interlaboratory comparison (ILC) aimed at detecting and quantifying DNA from two European anglerfish (Lophius budegassa, Lophius piscatorius), pike (Esox lucius) and sea bream (Spondyliosoma cantharus) using real-time qPCR. To detect amplification of the parvalbumin genetic marker, single and multiplex qPCR assays using EvaGreen® dye or TaqMan™ probes were used. Genomic DNA isolated from target fish species and an advanced DNA calibrator, gBlocks® gene fragments, were used as standards. The DNA of anglerfish, pike and sea bream as well as their mixtures were analysed together with 14 other non-target fish species. All target fish samples were correctly identified by the participating laboratories. Qualitative assessment of anglerfish and seabream DNA showed an accuracy rate of 100%, while pike DNA achieved a match rate of 99%. Validation of quantitative protocols in four different laboratories consistently achieved z-scores below 2, indicating satisfactory performance and confirming the high degree of similarity of laboratory results. Furthermore, high accuracy and efficiency were demonstrated for the quantification of anglerfish and seabream DNA by triplex qPCR using TaqMan™ probes. Regarding the selected gene marker, the major fish allergenic protein parvalbumin enables indirect detection and quantification of the allergen in the sample. Therefore, the use of proposed protocols can significantly contribute to protecting the health of consumers and to controlling the food market.Graphical abstract

The lack of knowledge about the majority of fish species harvested in Amazonian small-scale fisheries, in association with impacts from hydroelectric power plants, may lead to biodiversity loss and a decrease in the protein food supply for riverine Amazonians. This study uses existing datasets on fisheries and riverine developmental projects to infer effects associated with fish losses where actual data and outcomes are not available. The targeted fish species' status may be regarded as either threatened or there being no knowledge of their conservation requirements, biology or ecology. Among the 90 Amazonian fish species that are the most important for the diet of the riverine fishers, 78% are not assessed or their biological information is unknown, according to the IUCN Red List. Consequently, the effects created by the thoroughly disregarded trade-off between energy generation and food security in the planning of Amazonian land use have been worsened by the lack of biological and ecological information on fish species.

This study aimed to fill the gap of knowledge on this group of fishes by estimating the natural stock, species composition and biodiversity of target reef fishes from three regencies; Alor, East Flores (Flores Timur) and Southwest Maluku (Maluku Barat Daya/MBD) using underwater visual census method. A total of 176 species belong to 19 families of economically important target fish were recorded from 62 survey sites. The highest estimated stock is located in Southwest Maluku Regency – based on both abundance and biomass values, followed by Alor Regency and the lowest in East Flores Regency. Target fish species from the family of Caesionidae has the highest composition both based on abundance (74%) and biomass (40%). The highest species composition of target fish is from Pterocaesio tile (57.65%) which is more than 50% of the overall target fish. Community structure of target fish in the three regencies is still in a relatively good condition based on diversity index (H’), evenness (E) and no domination (C) of a single species occurs inside the target fish community, with exception in Alor Regency where the community of target fish is indicated to be under pressure. Biodiversity index by Bray-Curtis analysis in each location shows that most of the sites have the similarity of 67.51%, suggesting that there is not much difference in terms of target fish community structure between the three regencies.