Trachurus Trachurus Research Articles

Sperm ultrastructure of Prodistomum polonii (Digenea, Lepocreadioidea), an intestinal parasite of the Atlantic horse mackerel, Trachurus trachurus (Teleostei, Carangidae), from the Gulf of Gabes, Mediterranean Sea

The present study describes the ultrastructural organization of the mature spermatozoon of the lepocreadioid digenean Prodistomum polonii (Lepocreadiidae) by means of transmission electron microscopy (TEM). Live digeneans were collected from the digestive tract of the Atlantic horse mackerel Trachurus trachurus (Teleostei, Carangidae) captured in the coastal zone of the Mediterranean Sea, off La Chebba (Tunisia). The study reveals that the mature sperm cell of P. polonii is a filiform cell, which is tapered at both extremities. It exhibits the Bakhoum et al.’s type III of the digeneans spermatozoon characterized by the presence of: two 9+‘1’ axonemes, external ornamentation of the plasma membrane associated with cortical microtubules and located in the posterior part of the anterior region, two bundles of parallel cortical microtubules with their maximum number (15 microtubules) located in the middle part, and the presence of two mitochondria (one of them of moniliform type). According to the location of the external ornamentation, the male gamete of P. polonii presents a Quilichini et al.’s type 2 spermatozoon. Moreover, in the anterior spermatozoon extremity, there is a discontinuous and submembranous layer of electron-dense material. Whereas, the posterior spermatozoon extremity belongs to the Quilichini et al.’s cryptogonimid type. Our results are compared with the available data on digenean spermatology, in particular with species belonging to the superfamily Lepocreadioidea to highlight the potential criteria useful for phylogeny.

Which are the best environmental conditions for catching the beach‐seine target species? A Portuguese case study

AbstractThe beach‐seine fishery is a commercial fishing activity on the Portuguese coast, with reports dating as far back as the early 15th century. The main target species of this fishery are small pelagic fish such as Atlantic chub mackerel, Atlantic horse mackerel and sardine. To identify the best conditions for fishing the target species, catches of beach seine (2007–2017) were used and generalized linear models were applied, using a binomial and gamma distributions. The logistic model explained between 36.3% and 45.7% of the catches variability; the gamma model explained 9.1% and 46.9% of the catches variability, being month and wind direction the best covariates for the occurrence and/or abundance of the three small pelagic fishes in analysis. If the effort is directed to the days that meet the conditions found for each species (sardine: between May and October, wind NW, daytime; Atlantic horse mackerel: May, NW/NE wind, 800 m from the coastline; Atlantic chub mackerel: from July to August, NW moderate wind), a reduction in bycatch and discards can be achieved. This approach can have a positive economic and social impact, since it provides information for turning fisheries more efficient.

Effect of Origanum vulgare, Eugenia aromatica and Cinnamomum zeylanicum Essential Oils as Welfare Promoters in Gilthead Seabream during Slaughter

The potential of three essential oils, Origanum vulgare, Eugenia aromatica and Cinnamomum zeylanicum as slaughter anaesthetic agents, is presently assessed. Commercial stunning methods inducing rapid unconsciousness in fish before slaughtering, is urgently required. For now there is no acceptable method that can ensure kill fish humanely and all the commercially used methods of slaughter for farmed fish include a prolonged period of consciousness. Four slaughtering methods were applied, over-dose of four anaesthetics (three essential oils Origanum vulgare, Eugenia aromatica, Cinnamomum zeylanicum and 2-phenoxyethanol), asphyxia, bleeding and immersion in ice-water, in gilthead seabream (Sparus aurata L.). Asphyxia, considered inhumane, but solely used in all wild fish, is also being assessed in Atlantic horse mackerel (Trachurus trachurus L.). Plasma cortisol and DNA fragmentation were measured as indicators, to assess stress response and genotoxicity of essential oils. Overdose of all examined essential oils, proved to induce less stress in comparison to asphyxia, bleeding and immersion in ice-water. O. vulgare, E. aromatica and C. zeylanicum demonstrated higher efficiency in blocking plasma cortisol response to stress in gilthead seabream and lower genotoxic effect, compared to other slaughtering techniques. Asphyxia was confirmed as very stressful slaughtering method in both experimental and wild fish.

The effects of different artificial light wavelengths on some behavioural features of juvenile pelagic Atlantic horse mackerel, Trachurus trachurus (Actinopterygii: Perciformes: Carangidae)

The effects of different artificial light wavelengths on some behavioural features of juvenile pelagic Atlantic horse mackerel, Trachurus trachurus (Actinopterygii: Perciformes: Carangidae)

Genetic analysis provides insights into species distribution and population structure in East Atlantic horse mackerel (Trachurus trachurus and T. capensis).

Two sister species of horse mackerel (Trachurus trachurus and T. capensis) are described that are intensively harvested in East Atlantic waters. To address long‐standing uncertainties as to their respective geographical ranges, overlap and intraspecific population structure this study combined genetic (mitochondrial DNA and microsatellite) analysis and targeted sampling of the hitherto understudied West African coast. mtDNA revealed two reciprocally monophyletic clades corresponding to each species with interspecies nuclear differentiation supported by F ST values. The T. trachurus clade was found across the north‐east Atlantic down to Ghana but was absent from Angolan and South African samples. The T. capensis clade was found only in South Africa, Angola and a single Ghanaian individual. This pattern suggests that both species may overlap in the waters around Ghana. The potential for cryptic hybridization and/or indiscriminate harvesting of both species in the region is discussed. For T. capensis mtDNA supports high gene flow across the Benguela upwelling system, which fits with the species' ecology. The data add to evidence of a lack of significant genetic structure throughout the range of T. trachurus though the assumption of demographic panmixia is cautioned against. For both species, resolution of stock recruitment heterogeneity relevant to fishery management, as well as potential hybridization, will require more powerful genomic analyses.

Ingestion of microplastics by pelagic fish from the Moroccan Central Atlantic coast

As in the rest of the world, plastics are the most dominant marine litter category in Moroccan Atlantic waters. This work aims to identify the presence of microplastics in the stomach contents of three small pelagic species of the Central zone of the Atlantic, located between Cape Cantin (33°N) and Cape Boujdor (26°N): Scomber spp., Truchurus truchurus and Sardina pilchardus; Also, to map the spatial distribution of the investigated species. A total of 251 individuals were examined, composed by 118 Scomber spp, 82 Sardina pilchardus and 51 Trachurus trachurus. The characterization of microplastics ingested by those species was identified by FTIR. The results showed the presence of three polymers: Polyamide (PA), Acrylic (PC) and Polystyrene (PS), in 26% of the individuals studied. The presence of polymers was accumulated in Atlantic horse mackerel (Truchurus truchurus) with 30%, then in mackerels (Scomber spp.) with 27%, and European pilchardus (Sardina pilchardus) (9%). Fish containing microplastics in their stomachs are concentrated, mainly in the northern part of the study area. This zone has significant artisanal fishing activity and large rivers that can be source of microplastics.

Sperm characters in the Hemiuridae (Digenea): first data on Aphanurus stossichii (Aphanurinae) and Ectenurus lepidus (Dinurinae)

The present work provides the first ultrastructural analysis of spermatozoa of two digeneans (Aphanurus stossichii (Monticelli, 1891) and Ectenurus lepidus Looss, 1907) belonging to the unexplored subfamilies of the Hemiuridae, namely, the Aphanurinae and the Dinurinae. In March 2019, these hemiurids were collected respectively from the digestive tract of the bogue Boops boops (Teleostei, Sparidae) and the Atlantic horse mackerel Trachurus trachurus (Teleostei, Carangidae) captured in the coastal zone of the Mediterranean Sea, off La Chebba (Tunisia). The ultrastructural study reveals that both spermatozoa exhibit the Bakhoum et al.'s type II of the digenean sperm cells characterized by the presence of two 9+'1' axonemes, an external ornamentation of the plasma membrane not associated with cortical microtubules and located in the anterior part of the spermatozoon, a single bundle of cortical microtubules, the maximum number of cortical microtubules located in a middle part of the sperm cell, and one mitochondrion. Moreover, they share several ultrastructural features with the studied spermatozoa of Hemiuridae such as the presence of two axonemes with the 9+'1' trepaxonematan pattern, a reduced number of parallel cortical microtubules organized into one field with their maximum number located in the median (A. stossichii) or posterior (E. lepidus) part of the spermatozoon, an external ornamentation of the plasma membrane in the anterior part of the spermatozoon, one mitochondrion, a nucleus, and a small amount of glycogen granules. However, the two studied hemiurids could be distinguished by the morphology of the anterior and posterior spermatozoon extremities and the presence of mitochondrial matrix granules in A. stossichii.

Spawning period, size at first sexual maturity and sex ratio of the Atlantic horse mackerel, Trachurus trachurus (Linnaeus, 1758) (Perciformes Carangidae), caught in Béni-Saf Bay, W-Mediterranean (Algeria)

Spawning period, size at first sexual maturity and sex ratio of the Atlantic horse mackerel, Trachurus trachurus (Linnaeus, 1758) (Perciformes Carangidae), caught in Béni-Saf Bay, W-Mediterranean (Algeria)

PelagiCam: a novel underwater imaging system with computer vision for semi-automated monitoring of mobile marine fauna at offshore structures.

Engineered structures in the open ocean are becoming more frequent with the expansion of the marine renewable energy industry and offshore marine aquaculture. Floating engineered structures function as artificial patch reefs providing novel and relatively stable habitat structure not otherwise available in the pelagic water column. The enhanced physical structure can increase local biodiversity and benefit fisheries yet can also facilitate the spread of invasive species. Clear evidence of any ecological consequences will inform the design and placement of structures to either minimise negative impacts or enhance ecosystem restoration. The development of rapid, cost-effective and reliable remote underwater monitoring methods is crucial to supporting evidence-based decision-making by planning authorities and developers when assessing environmental risks and benefits of offshore structures. A novel, un-baited midwater video system, PelagiCam, with motion-detection software (MotionMeerkat) for semi-automated monitoring of mobile marine fauna, was developed and tested on the UK's largest offshore rope-cultured mussel farm in Lyme Bay, southwest England. PelagiCam recorded Atlantic horse mackerel (Trachurus trachurus), garfish (Belone belone) and two species of jellyfish (Chrysaora hysoscella and Rhizostoma pulmo) in open water close to the floating farm structure. The software successfully distinguished video frames where fishes were present versus absent. The PelagiCam system provides a cost-effective remote monitoring tool to streamline biological data acquisition in impact assessments of offshore floating structures. With the rise of sophisticated artificial intelligence for object recognition, the integration of computer vision techniques should receive more attention in marine ecology and has great potential to revolutionise marine biological monitoring.

Single sample preparation for brominated flame retardants in fish and shellfish with dual detection: GC-MS/MS (PBDEs) and LC-MS/MS (HBCDs).

An analytical method for the simultaneous determination of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) in fish, shellfish and muscle of terrestrial animals was developed as an extension of a previously validated method for PBDE analysis. A single sample preparation based on QuEChERS-like extraction and a two-step clean-up, followed by a dual instrumental detection, was implemented. GC-MS/MS was used for PBDEs and LC-MS/MS for HBCDs. The method allows the quantification of fifteen PBDEs (28, 47, 49, 66, 77, 85, 99, 100, 138, 153, 154, 183, 197, 206, 209) and three HBCD isomers (α, β and γ), reaching 10 pg/g LOQs for all the analytes except BDE 206 and 209 (100 pg/g LOQ). The validated method was applied to the analysis of 12 fish and shellfish species (sole, spiny dogfish, smooth-hound, mackerel, swordfish, grey mullet, cod, anchovy, red mullet, Atlantic horse mackerel, tuna fish and mussel) collected in central Italian markets accounting for a total of 44 samples. Generally, ΣPBDEs showed higher concentration than ΣHBCDs except in the case of mussels in which ΣHBCDs > ΣPBDEs. Cod and smooth-hound are the least contaminated species among those analysed in the present study, whereas the highest brominated flame retardant (BFR) levels were found in spiny dogfish samples. The measured contamination levels were generally comparable to or lower than those already published in European studies. Literature data for HBCDs in European fish and shellfish were hard to find; therefore, PBDE and HBCD levels were also compared with European Environmental Quality Standard (EQS) in biota (Directive 2013/39/EU). EQSs for HBCDs are six orders of magnitude higher than those for PBDEs; therefore, while no exceedance was observed for the first, almost all the samples analysed for PBDEs were above EQSs. The presented preliminary data on PBDEs and HBCDs are among the first published in marine fish and shellfish commercialised in Central Italy. Graphical abstrac.

Mercury accumulation in fish species along the Portuguese coast: Are there potential risks to human health?

This paper aimed at evaluating the total mercury content in five common fish species from the western European Atlantic coastal waters, and the associated risk of consumption. Mercury concentrations in muscle of Atlantic mackerel (Scomber scombrus), Atlantic chub mackerel (Scomber colias), European anchovy (Engraulis encrasicolus), Atlantic horse mackerel (Trachurus trachurus) and European pilchard (Sardina pilchardus) ranged from 0.003 to 0.20 mg kg−1 wet weight, and no significant differences were observed between the average concentration in each species. A significant increasing trend in mercury content with fish size was observed for all species (except for European anchovy), suggesting mercury bioaccumulation throughout their life cycle. Still, the mercury content was far below the European Food Safety Authority and World Health Organization food safety thresholds in all species, highlighting the low risk to human health due to the ingestion of these species and the importance of consumer options for risk reduction.

Phenotypic and Molecular Characterization of Lacinutrix venerupis Isolated from Atlantic Horse Mackerel Trachurus trachurus.

The aim of the present study was to characterize two gram-negative bacterial strains that were isolated from diseased Atlantic Horse Mackerel Trachurus trachurus in 2017. Based on the results obtained from the biochemical and chemotaxonomic characterization, the isolates were identified as Lacinutrix spp. The highest similarity of the 16S rRNA gene sequences was obtained with the strain L.venerupis CECT 8573T (99.1%), while other species showed similarities of 98% (L.jangbogonensis) and 97% (L.algicola and L.mariniflava). Molecular characterization by repetitive element (REP)-PCR and enterobacterial repetitive intergenic consensus (ERIC)-PCR, as well as proteomic characterization by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS), demonstrated heterogeneity between the strains from the Atlantic Horse Mackerel and the type strain, CECT 8573T . The virulence of one of the isolates for Turbot Scophthalmus maximus, European Sea Bass Dicentrarchus labrax, Senegalese Sole Solea senegalensis, and Rainbow Trout Oncorhynchus mykiss was assessed under experimental conditions. No mortalities were recorded after intraperitoneal injections with high doses of bacteria (1×109 CFU/mL). Thus, further studies are necessary to elucidate the impact of this bacterial species as a fish pathogen.

Elemental Study of Common Iced Fish Species Sold in Akure, Ondo State, Nigeria

There is a death of information on the mineral composition of essential, toxic elements of commonly consumed frozen fishes in Nigeria, hence, this study was conducted to determine the proximate, elemental composition and also estimate the daily intake of the minerals obtained in the frozen samples of Hake (Merluccius merluccius), Sardine (Sardinella eba), Chub Mackerel (Scomber jopanicus), Atlantic horse Mackerel (Trachurus trachurus) and, Croaker (Pseudolithus elongatus) obtained from four markets in Akure, Ondo State, Nigeria. The fish species examined contained appreciable concentrations of protein which ranged from 15.19% in Chub mackerel to 21.75 % in Atlantic horse mackerel. The ash and moisture content suggest that the fish species are a good source of minerals and a veritable medium for microbial proliferation respectively, while, the crude fat value ranging between 0.16 % in Atlantic horse mackerel to 0.27 % in Hake showed that they are lean fat fishes. The Estimated Dietary Intake (EDI) of the macro and microelements analysed in the fish species (except for phosphorus) fell short of the Dietary Reference Intake (DRI) that were established by the Institute of Medicine. However, the concentrations of toxic elements such as lead, arsenic and cadmium exceeded the maximum limits set for these elements in foods, and this consequently poses a long term risk as a result of the bioaccumulation and biomagnifications of these toxic elements in the body.

Bivalves boost biodiversity

Bivalves boost biodiversity

Number Dynamics of Mass Ichthyoplankton Species in the Waters of Morocco

Data on the number dynamics of the mass fish species at early developmental stages in the northern and southern regions of Morocco during 2003–2016 have been analyzed. The values of number index and absolute number of eggs and larvae of the mass fish species have been calculated. As a rule, the values of absolute number of ichthyoplankton are 1.3–2.9 times higher than of the number index values. In general, the trends of interannual fluctuations of these values are similar. The study revealed that the patterns of fluctuations of the subtropical fish species at early developmental stages (European pilchard Sardina pilchardus, Atlantic horse mackerel Trachurus trachurus, and mackerel Scomber japonicus colias) are similar over the whole study area within the Morocco economic zone (32°–21° N). The fluctuations in the number of the tropical fish eggs and larvae (round sardinella Sardinella aurita and Cunene horse mackerel T. trecae) are not identical in the northern and southern parts of Morocco. No clear correlation between these fluctuations in the bordering regions is revealed.

Regional climate, primary productivity and fish biomass drive growth variation and population resilience in a small pelagic fish

Abstract Environmental change often combined with selective harvesting has profound and diverse impacts on marine fish populations. Unlocking the biological consequences of these effects on wild fish is notoriously challenging, especially in highly productive but naturally variable systems with uncertain futures such as Eastern Boundary current systems. Here, we developed otolith increment-based growth chronologies covering half a century (53 years) for a small pelagic fish (Atlantic horse mackerel, Trachurus trachurus) in the northern limb of the Canary current upwelling system. We used increasingly complex mixed-effects models to partition individually resolved growth variation among intrinsic (Age and Age-at-capture) and extrinsic (biotic and abiotic factors) sources in four complementary data sets: a general population chronology, and three chronologies derived from age groups that reflect ontogenetic habitat shifts. First, we investigated the timing and scale of growth phase shifts and assessed the effects of extrinsic factors on inter-annual growth variation. Second, we quantified among and within cohort growth variability over time. Our results provided strong evidence for inter-annual SST and primary productivity variation impacting on Atlantic horse mackerel growth. We also identified phase shifts in growth that point to larger ecosystem-wide changes (regime shifts), potentially driven by large-scale climatic indices, such as North Atlantic Oscillation and East Atlantic pattern. Cohort-dependent growth effects likely reflect persistent environmental influences and density dependence. Further, we found evidence for carryover effects in growth whereby a poor start in life tended to persist despite compensatory growth being observed in some individuals. We show how population productivity can be impacted by multiple, interacting environmental and biotic factors leading to potential ecosystem regime shifts. Such information is key to understand recruitment dynamics and population persistence, and will have important implications for fisheries management and to those seeking to understand the effects of large-scale climate change on marine productivity.

Implementation of an end-to-end model of the Gulf of Lions ecosystem (NW Mediterranean Sea). I. Parameterization, calibration and evaluation

An end-to-end model named OSMOSE-GoL has been built for the Gulf of Lions, the main French Mediterranean fishing area. This spatialized dynamic model links the coupled hydrodynamic and biogeochemical model Eco3M-S/SYMPHONIE (LTL – low trophic level model) to OSMOSE (HTL – high trophic level model). It includes 15 compartments of living organisms, five from the LTL model (i.e. nanophytoplankton, microphytoplankton, nanozooplankton, microzooplankton and mesozooplankton) and ten from the HTL model (northern krill, southern shortfin squid, European pilchard, European anchovy, European sprat, Atlantic horse mackerel, Atlantic mackerel, blue whiting, European hake and Atlantic bluefin tuna). With the exception of northern krill and European sprat, all HTL species are commercially exploited and undergo fisheries mortality pressure. The modeled species represent more than 70% of annual catches in this area. This paper presents the parameterization, calibration and evaluation of this model with satellite data for phytoplankton and with biomass, landings, diet and trophic level data for HTL groups. For most species, the diets in output of OSMOSE-GoL are similar to field and literature data in terms of dominant prey groups and species. However, some differences were observed. Various reasons may explain the mismatch between the modeled diet and field data. Benthic prey sometimes observed in the stomach content of the HTL predators were not modeled in OSMOSE-GoL. Field studies were carried out at specific periods and locations, while our data concern the period 2001–2004 and the entire modeled domain. Inter- and intra-annual variations in spatial distribution and density of prey may also explain these differences. The model estimates trophic level values similar to those cited in the literature for all the HTL compartments. These values are also close to the trophic levels estimated by a previous Ecopath model for the same area and period. Even though some improvements are still possible, this model may already be of use to explore fishery or Marine Protected Areas scenarios for socio-ecosystem management issues.

Production of Valuable Compounds and Bioactive Metabolites from By-Products of Fish Discards Using Chemical Processing, Enzymatic Hydrolysis, and Bacterial Fermentation.

The objective of this report was to investigate the isolation and recovery of different biocompounds and bioproducts from wastes (skins and heads) that were obtained from five species discarded by fishing fleets (megrim, hake, boarfish, grenadier, and Atlantic horse mackerel). Based on chemical treatments, enzymatic hydrolysis, and bacterial fermentation, we have isolated and produced gelatinous solutions, oils that are rich in omega-3, fish protein hydrolysates (FPHs) with antioxidant and antihypertensive activities, and peptones. FPHs showed degrees of hydrolysis higher than 13%, with soluble protein concentrations greater than 27 g/L and in vitro digestibilities superior to 90%. Additionally, amino acids compositions were always valuable and bioactivities were, in some cases, remarkable. Peptones that were obtained from FPHs of skin and the heads were demonstrated to be a viable alternative to expensive commercial ones indicated for the production of biomass, lactic acid, and pediocin SA-1 from Pediococcus acidilactici.

An overview of small-scale fisheries in the Northern Portuguese coast

An overview of small-scale fisheries in the Northern Portuguese coast

Prey preferences and ontogenetic diet shift of European hake Merluccius merluccius (Linnaeus, 1758) in the central Mediterranean Sea

This study focuses on the ontogenetic diet change of European hake (Merluccius merluccius) in the north sector of the Strait of Sicily (SoS), central Mediterranean Sea. The species is one of the most important fish predators within the Mediterranean marine ecosystem and one of the main target species for local fisheries. A total of 2669 hake specimens between 7.5 and 67 cm of total length (TL) were collected in 2014–2015. The sample was divided into nine size classes and quantitative feeding indices were calculated for each size-class in order to analyse ontogenetic changes in prey preferences. Hierarchical cluster analysis and non-metric multidimensional scaling (nMDS) showed the occurrence of three main hake feeding guilds separated at 50% similarity. Euphausiids and mysids dominated the diet of hake smaller than 14 cm TL and crustacean decapods and fish were the main prey of hake between 14.5 cm to 17.5 cm TL. A shift toward pelagic and necto-benthic fish occurred over 18 cm TL: hake between 18 and 32 cm TL prey mostly upon Atlantic horse mackerel (Trachurus trachurus) whilst the silver scabbardfish (Lepidopus caudatus) was an important prey for hake over 32 cm TL. The study highlighted the key role played by the Atlantic horse mackerel for hake diet in the SoS, which is different to what has been previously observed in other Mediterranean areas where piscivorous hake feed substantially on small pelagic fish, such as anchovy and sardine. Information on hake diet composition, as provided in this study, can be integrated with data on consumption rate and population size to develop multispecies models leading to a quantitative understanding of the role of hake in the ecosystem.