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Ecosystem models provide a better understanding of fish populations and their environmental impacts. In this research, data from the Moroccan main ports landing logbook, along with two climate scenarios (RCP 2.6 and RCP 8.5), were used. Generalized additive models (GAMs) were applied to analyze the relationships between landing per unit effort (LPUE), fishing effort, and environmental factors for both species. The study investigated the influence of climate scenarios on LPUE and fishing effort to project future potential landings for both species. In addition, it compared the proportional changes between 2022 and 2100, relative to the 2010-2022 average in the southern Alboran Sea. Phytoplankton was identified as the main driver of sardine LPUE, while sea level anomaly influenced Horse Mackerel LPUE. By the end of the 21st century, Sardine potential landings are projected to increase by +15% under RCP 8.5 and +80% under RCP 2.6 compared to the 2010-2022 average. In contrast, the Atlantic horse mackerel potential landings are expected to increase by +200% under RCP 2.6, while decreasing by -100% under RCP 8.5 by the end of the century. This research underscores the importance of considering environmental factors in managing small pelagic fisheries to ensure their sustainability in a changing climate. [ABSTRACT FROM AUTHOR]

The present study focuses on the detailed description of postovulatory follicles (POFs) resorption and atresia in horse mackerel from Algerian waters. From February 2013 to February 2014, 155 female horse mackerel were randomly collected. Histological sections of ovaries were analyzed. Few POFs (7.28% of early POFs and 2.91% of old POFs of the total observed oocytes) were detected. Morphological changes of POF resorption were discussed in the current study. No particular shape was observed. Four types of atretic oocytes were determined: α = 34.38%, β = 5.28%, δ = 2.37% and γ = 0.94%, which was reported for the first time in horse mackerel. The incidence of α atresia was higher in the yolked (21.48%) than in the unyolked oocytes (12.89%). α atretic oocytes can be classified into two main types: non-bursting (capsulated, lipoidal and cystic atresia) and bursting (multiple bursts, single bursts, phagocytic bursts and liquified bursts). Further studies are required to better understand the reproductive strategies of fish in relation to postovulatory follicle resorption and atresia.

Fourier-transform near-infrared spectroscopy (FT-NIRS) has recently been used to reduce the processing time for estimates of annual age in several fish species. The present study represents the first application of this technique to marine organisms from the European waters. Atlantic horse mackerel (Trachurus trachurus) from the central Mediterranean Sea was selected for its ecological role, its socioeconomic value, and because its age is regularly estimated by otolith reading under a stereomicroscope for stock assessment purposes. Absorption spectra of the whole otoliths were acquired by FT-NIRS across a multiyear dataset, obtained during acoustic surveys carried out in different regions of the central Mediterranean Sea. The acquired spectra were processed to optimize calibration models to predict age. The best linear models obtained by the optimizing procedure predicted age successfully with a coefficient of determination of 0.95-0.96, mean squared error of 0.5 years, and bias <0.03 years. Although regional calibration models were also obtained separately, the models with all regions combined appeared much more robust and encompassing the whole age range, suggesting its usefulness for the entire spatial distribution range considered in the preset study. The use of FT-NIRS allowed to successfully predict age for horsemackerel between the ages 1 and 14, with similar or better precision (and bias) of the traditional methods, also increasing the standardization by repeatability of age assignments. The preliminary results obtained by this study encourage further effort to fine-tune the calibration model for new species, in order to apply a precise, rapid, costeffective method for stock assessment purposes of Mediterranean fish resources. [ABSTRACT FROM AUTHOR]

The Atlantic horse mackerel, Trachurus trachurus, is a semi-pelagic fish species with a broad distribution in the temperate, tropical, and subtropical coastal waters of the Atlantic, Mediterranean and Indian Oceans. As a significant species for both commercial and recreational fisheries, it plays a pivotal role in the marine food web. This review synthesized current knowledge of the ecology, reproduction, and growth patterns of T. trachurus, emphasizing its critical biological attributes. Furthermore, it examined the main threats and conservation challenges this species faces, alongside the implications for fishery management. The review culminated with strategic recommendations for future research and monitoring initiatives aimed at filling the existing knowledge gaps and enhancing fishery’s sustainability. [ABSTRACT FROM AUTHOR]

The increase in hard artificial structures in the marine environment is contributing to ocean sprawl. As well as adding hard structure to the seabed, mussel aquaculture adds rope droppers and anchor lines to the water column, where such structure would otherwise be absent. This paper aims to monitor the effects of mussel headlines on the pelagic fish community over time, as well as to investigate whether there is an interaction between the age of cultivated mussels with the number of epibiota species and the abundance of pelagic fishes. Two surveys were carried out: a time series monitoring survey to assess whether the mussel headlines change the surrounding fish species relative to control areas over time, and a fish aggregation device effect survey to investigate whether older and larger mussels support greater abundances of pelagic fishes and epibiota. The most abundant fish species was Atlantic horse mackerel, Trachurus trachurus, with significantly greater numbers recorded around ropes growing older mussels. Results from the surveys show that the physical farm infrastructure has provided a substrate for colonisation by a variety of epibiota: A total of 21 species were recorded growing on the mussel ropes. Furthermore, the older and larger the mussels become, the greater the numbers of epibiota taxa that can colonise, coupled with a greater abundance of pelagic fish recorded around the ropes. The sustainable development of offshore Blue Industries is essential to produce renewable resources. This study brings essential evidence for marine managers and regulators that offshore mussel farming can provide benefits for pelagic and benthic species of both conservation and commercial importance while producing sustainable protein to feed a growing population. [ABSTRACT FROM AUTHOR]

Fourier-transform near-infrared spectroscopy (FT-NIRS) has recently been used to reduce the processing time for estimates of annual age in several fish species. The present study represents the first application of this technique to marine organisms from the European waters. Atlantic horse mackerel (Trachurus trachurus) from the central Mediterranean Sea was selected for its ecological role, its socioeconomic value, and because its age is regularly estimated by otolith reading under a stereomicroscope for stock assessment purposes. Absorption spectra of the whole otoliths were acquired by FT-NIRS across a multiyear dataset, obtained during acoustic surveys carried out in different regions of the central Mediterranean Sea. The acquired spectra were processed to optimize calibration models to predict age. The best linear models obtained by the optimizing procedure predicted age successfully with a coefficient of determination of 0.95–0.96, mean squared error of 0.5 years, and bias

Horse mackerel is a semi-pelagic fish widely distributed in the eastern Atlantic, where it represents a species of interest for fisheries and is subject to intense exploitation, leading to its global classification as a vulnerable species by IUCN. In the Northwestern (NW) Mediterranean Sea, the knowledge of their distribution, abundance and main biological parameters is fundamental to achieve their sustainable exploitation and contribute to the ecosystem approach to fisheries management. The time series (2009–2020) data set analyzed in this study came from two geographical subareas (GSAs) defined by the General Fisheries Commission for the Mediterranean (GFCM), Northern Spain (GSA06) and Northern Alboran Sea (GSA01) sampled in July during the MEDiterranean International Acoustic Survey (MEDIAS). Our results suggest that in summer, a higher concentration and aggregation of fish exists in GSA01, with a density ten times greater than in GSA06. Possible life history changes can be inferred through the analysis of the biological parameters of Trachurus trachurus in the NW Mediterranean Sea. In both GSAs, the annual decline of the size at first maturity (L50) and condition factor (Kn) was prominent. Moreover, the population structure lacked adult modes that could guarantee a successful recuperation of future stocks. Nonetheless, fish inhabiting GSA01 seem to have a better adaptive response to the events responsible for these alterations. In comparison, GSA01 is under less fishing pressure and the upwelling occurring in this area contributes to a higher availability of food, in addition to reducing the increases in sea surface temperature due to climate change during the study period. [ABSTRACT FROM AUTHOR]

Hysterothylacium aduncum is a parasitic nematode that infects mainly marine fish. The information on the heterogeneity in the aggregation of macroparasites in fish species is still limited, particularly for the Raphidascarid nematode H. aduncum that infects exploitable marine fish species including horse mackerel (Trachurus trachurus). This study aimed to investigate the heterogeneity of the distribution of H. aduncum to better understand macroparasite aggregation in marine fish. Weibull tests comprising Maximum likelihood were used to analyze the frequency distribution of parasites within a fish host population over the three years period. The parasite, H. aduncum (third larval stage) prevalence was found to be 88% and the condition factor was 1.30∓0.029 in un-infected fish and 1.12∓0.022 in infected fish. The clustered pattern was observed in H. aduncum in horse mackerel. The relation between parasite load and the fish condition factor was found to be significant and conformity of length and weight was affected by parasite load. It is the first time that aggregation has been observed in H. aduncum distribution and forecasts of nematode intensity in horse mackerel. The findings related to the large individual variations suggest that this pattern is significant and should be considered for host-parasite dynamics. [ABSTRACT FROM AUTHOR]

Atlantic mackerel (Scomber scombrus) and Atlantic horse mackerel (Trachurus trachurus), locally known as kote, are fishery species consumed in Nigeria due to their high nutritional values. This research determined the nutritional composition of the local dried fish, Scomber scombrus and Trachurus trachurus. Results for Scomber scombrus shows the mean value of the moisture, ash, crude fat, crude fiber, and crude protein contents in percent (%) as: 5.260.00, 5.200.10, 35.600.00, 2.900.10 and 46.300.01 respectively. For Trachurus trachurus, the moisture, ash, crude fat, crude fiber, and crude protein contents in percent (%) were 9.520.00, 32.260.01, 24.140.00, 11.910.85 and 40.950.00 respectively. The mineral composition of Scomber scombrus was as follows: Sodium (Na) had the highest mineral composition with 78.90 mg/100g, followed by magnesium (Mg) with 15.90 mg/100g, manganese (Mn) with 0.86 mg/100g, zinc (Zn) with 0.282 mg/100g, and iron (Fe) with 0.10 mg/100g. Trachurus trachurus has magnesium (Mg) at 27.00 mg/100g as its highest mineral composition, followed by sodium (Na) at 22.50 mg/100g, zinc (Zn), iron (Fe) at 0.17 mg/100g, and manganese (Mn) at 0.09 mg/100g. It is concluded from the study, that Scomber scombrus and Trachurus trachurus are good sources of essential nitrates, fat, proteins containing essential amino acids, and other micronutrients that are beneficial to human health.

The present study aimed to evaluate the fishery status of the Atlantic horse mackerel (Trachurus trachurus) stock in the western Egyptian Mediterranean waters. Random monthly samples of fish were collected during the period from April 2015 to March 2016, with a total of 1054 fish. Growth parameters were determined and the vectors of natural mortality (M) by age, total mortality (Z) and fishing mortality (F), length cohort analysis, and Beverton & Holt Yield per recruit analysis were performed by FiSAT and Virtual Population Analysis (VIT software) programs to estimate the limit and target reference points. The present results showed that the Von Bertalanffy growth parameters were L8 = 29.58 cm, K = 0.27 years-1, and t0 = - 1.49 year. The mean values of Z, F and M were 0.828, 0.575 and 0.253 year-1, respectively. The exploitation rate (E) was 0.694 year. The current yield per recruit (Y/R), biomass per recruit (B/R), and spawning stock biomass (SSB) at the current fishing mortality (0.575 year-1) were 14.27, 31.35 and 12.15g, respectively. The percentage of the current B/R to the virgin biomass was 25.11%. The reference point F0.1 = 0.27, and the limit reference point (FMAX) was 0.48 year-1. These two values are lower than the current value of fishing mortality (0.575 year-). The ratio between FC and F0.1 was 2.128; this value indicates that T. trachurus stock in the Egyptian Mediterranean waters is at a high over exploitation state. [ABSTRACT FROM AUTHOR]

Data on Atlantic horse mackerel Trachurus trachurus (Linneus, 1758) were collected along 8-year acoustic surveys (2011-2018). Age and growth variability of horse mackerel from the Central Mediterranean Sea were investigated within different, contrasting habitats, from the south of Sicily to the north Tyrrhenian (Ligurian Sea). Data from satellite provided the habitat features along the study period over the whole surveyed area. For comparison purposes, according to the ecosystems difference the study area has been split into four subareas: Strait of Sicily (SoS), North of Sicily (NS), south Tyrrhenian Sea (ST) and north Tyrrhenian Sea (NT). In terms of the FAO Geographical Sub-Area definition the SoS corresponding to GSA15 and 16, NS to GSA 10 south, ST to GSA10 north and NT to GSA 9. Results showed a growth homogeneity in the study area, suggesting a unique stock inhabiting these waters. The only exception was recorded for juveniles (Age 0 class) in the SoS, where a lower size at age was detected compared to other areas. A multiple linear modelling analyses suggested that variability in length at age 0 was mainly linked to the oceanographic differences between an upwelling driven system (Strait of Sicily) and the other ecosystems, where enrichment processes are mainly due to river runoff (relevant in ST and NT). Namely, Absolute Dynamic Topography (ADT) and body condition factor (Kn) were significantly related to differences in length at age 0. Results revealed that currents (and gyres) are among the principal abiotic factors controlling Atlantic horse mackerel growth in its first year of life, suggesting that circulation and food-related processes (i.e., zooplankton concentration) are of major importance for this species. Finally preliminary observations suggest the Strait of Sicily may be the main spawning area among those analyzed.

In this study 288 length-weight relationships of some fish species from the Turkish coasts of Black Sea were gathered from 138 studies, which were conducted by several researchers between 1989 and 2021. For all species, the "b" values ranged from 2.49 for Trachurus trachurus to 3.75 for Alosa caspia. The expected range of 2.5

It is supported by studies that heavy metals and other water pollutants can reach humans through the food chain because of accumulation in organs of digestion, respiration, and muscles of fish, and may cause toxic effects depending on the amount of pollution and accumulation. This study was carried out by obtaining Horse mackerel samples from the Çanakkale Strait, which are fish species with high economic and nutritional value, as well as frequently consumed, seasonally (spring, summer, autumn, and winter). In the study, the tissues dissected from the dorsolateral muscles of the fresh fish were taken into Bouin's fixative, and sections were taken after routine histological follow-up. The findings revealed degenerative and inflammatory findings in the muscle tissues of fish caught especially in the autumn season. In addition, a statistically significant difference was found in autumn samples in terms of immunoreactivity (p<0.05). [ABSTRACT FROM AUTHOR]

This study revealed a previously undocumented association between a teleost and a shark. Atlantic horse mackerel Trachurus trachurus were observed following spiny dogfish Squalus acanthias during 3 consecutive years (2018–2020) on off-shore banks in Kattegat (57°N; 11°E, Sweden). The observations were made by the use of stereo-BRUV (baited remote underwater stereo-video systems). Our findings provide additional information about relationships between sharks and teleosts and suggest that stereo-BRUV can add to the ecological knowledge gained from the commonly deployed trawl surveys in temperate waters such as the Kattegat. With the increasing use of BRUVs in areas where the method has rarely been used before, such as higher latitudes or deeper water, observations as the one described here will likely increase. We urge the growing community of BRUVvers to make use of the methods full potential and to share not only estimations of abundance of different species but also observations of species associations and behaviors. These observations are important for better understanding of the interaction between species and could be important knowledge for targeted management measures. [ABSTRACT FROM AUTHOR]

We present a genome assembly from an individual Trachurus trachurus (the Atlantic horse mackerel; Chordata; Actinopteri; Carangiformes; Carangidae). The genome sequence is 801 megabases in span. The majority of the assembly, 98.68%, is scaffolded into 24 chromosomal pseudomolecules. Gene annotation of this assembly on Ensembl has identified 25,797 protein coding genes.

This study investigated the distribution of nematode larvae of Anisakidae and Raphidascarididae (genera Anisakis and Hysterothylacium) in Trachurus trachurus (Linnaeus, 1758) in the Ligurian and central-northern Tyrrhenian Seas. The relationship between the number of parasites and the length and weight parameters of the fish was assessed, and the possible effect of the parasites on the condition factor was evaluated. A total of 190 T. trachurus specimens were collected in July 2019. Parasites were found in 70 individuals. A total of 161 visible larvae were collected in the viscera. Morphological analysis revealed the presence of Anisakis spp. in 55 fish and Hysterothylacium spp. in 15 fish, while 5 fish showed coinfection with both genera. The specimens subjected to PCR (n = 67) showed that 85% of the Anisakis larvae analyzed belonged to the species A. pegreffii, while the remaining 15% belonged to hybrids of A. pegreffii-A. simplex (s.s.). A total of 58% (n = 7) of the Hysterothylacium larvae analyzed belonged to the species H. fabri, while 42% belonged to the species H. aduncum. Our results support the hypothesis that infection with these parasites does not affect the condition of the fish host analyzed, and that body size and depth are major drivers in determining infection levels with Anisakid and Raphidascaridid nematodes. [ABSTRACT FROM AUTHOR]

To discriminate potential stock units of the Atlantic horse mackerel Trachurus trachurus within the putative Moroccan–Saharan stock, we investigated the morphological variation of this species from three fishing areas (from the north to the south: Larache, Safi and Dakhla) in the Moroccan Atlantic coastal waters. We used a geometric morphometric approach based on 30 truss measures derived from 14 landmarks in 165 fish specimens. We compared fish from three areas using a multivariate analysis including discriminant analysis and Procrustes technique. We found indications of at least two subunits: a differentiated subgroup in the north off Larache, probably a self-recruiting population or a locally adapted morphotype, and two overlapped subunits, respectively in the mid and southern Moroccan Atlantic coast off Safi and Dakhla. Examination of the contribution of each morphometric variable to canonical functions indicated that differences among samples seemed to be associated with morphological changes in the anterior and posterior parts of body, which may indicate adaptations to local environmental conditions and habitat use. Further investigations using other methods are needed to confirm the identified stock units. The present study and the obtained results on such a vulnerable declining small pelagic species are of great importance for fish stock assessment management and practice, but also have ecological and evolutionary implications related to local adaptations in fish populations that are under intense fishing pressure as an induced evolutionary selective force, which affects several adaptive traits. [ABSTRACT FROM AUTHOR]

The generation of omic resources is central to develop adequate management strategies for species with economic value. Here, we provide high-coverage RNA-seq datasets of liver tissue (containing between 80,2 and 88,4 million of paired-end reads) from four wildtype teleost species with high commercial value: Trachurus trachurus (TTR; Atlantic horse mackerel), Scomber scombrus (SSC; Atlantic mackerel), Trisopterus luscus (TLU; pout), and Micromesistius poutassou (MPO; blue whiting). A comprehensive assembly pipeline, using de novo single and multi-kmer assembly approaches, produced 64 single high-quality liver transcriptomes – 16 per species. The final assemblies, with N50 values ranging from 2,543–3,700 bp and BUSCO (Benchmarking Universal Single-Copy Orthologs) completeness values between 81.8–86.5% of the Actinopterygii gene set, were subjected to open reading frame (ORF) prediction and functional annotation. Our study provides the first transcriptomic resources for these species and offers valuable tools to evaluate both neutral and selected genetic variation among populations, and to identify candidate genes for environmental adaptation assisting in the investigation of the effects of global changes in fisheries. Measurement(s) RNA • transcriptome • sequence_assembly • sequence feature annotation Technology Type(s) RNA sequencing • sequence assembly process • sequence annotation Factor Type(s) teleost species Sample Characteristic - Organism Trachurus trachurus • Scomber scombrus • Trisopterus luscus • Micromesistius poutassou Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.12533171 [ABSTRACT FROM AUTHOR]

Rocinela dumerilii (Lucas, 1849) is obtained on the horse mackerel, Trachurus trachurus (Linnaeus, 1758) from the Sea of Marmara, in Turkey. This species is a free-living organism from the Aegean Sea of Turkey, the Mediterranean Sea and Atlantic. Its micropredator behaviour is discovered for the first time in this study. Elthusa sinuata (Koelbel, 1879) is also collected on the gill cavity of Fries's goby, Lesueurigobius friesii (Malm, 1874) in this study. This host is a new record for Elthusa sinuata. The morphological characters of Rocinela dumerilii species are given by drawings. [ABSTRACT FROM AUTHOR]

The gill tissue is the main site of metabolic enzymes or compensation, with the kidney tissue playing a supporting role. At the gill tissue, carbonic anhydrase enzymes (CAs) catalyze the hydration of CO2 to HCO3− and H+ for production to the H2O. In this work, the CA enzyme was purified from horse mackerel (Trachurus trachurus) gill with a specific activity of 21,381.42 EU/mg, purification fold of 150.61, total activity of 2347.68 EU/mL, and a yield of 16.13% using sepharose 4B-L-tyrosine-sulfanilamide affinity gel chromatography. For recording the enzyme purity, gel electrophoresis was performed, and single band was seen. The molecular weight of this enzyme was found approximately 35 kDa. Also, the inhibitory effects of different pesticides such as thiram, clofentezine, propineb, deltamethrin, azoxystrobin, and thiophanate and heavy metal ions such as Fe2+, Cu2+, Co2+, Pb2+ Hg2+, and As3+ on horse mackerel gill tissue CA enzyme activities were investigated. Our results indicated that these pesticides and metal ions showed inhibitory effects at low nanomolar and millimolar concentrations for fish gill CA enzymes, respectively. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

• Development of 53-year long growth chronologies of pelagic fish in upwelling system. • SST, primary productivity and fish biomass impact growth of Atlantic horse mackerel. • Identification of ecosystem-wide changes potentially driven by climatic indices. • Evidence for carryover effects in growth performance of Atlantic horse mackerel. • Multiple, interacting environmental and biotic factors affect marine productivity. 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. [ABSTRACT FROM AUTHOR]

Abstract Understanding drivers of fish maturity are essential to predict the productivity, stability, and resiliency of exploited populations. In terms of horse mackerel (Trachurus trachurus), in the eastern Atlantic Ocean and the Mediterranean Sea, size at maturity estimates date back to the 1940s and throughout its range. However, many older estimates may not reflect current maturity rates. This is because past methods were imprecise, or environmental or fishing effects may change maturity rates, and some stock areas have been overlooked. To address this data gap for the Central Mediterranean Sea, female horse mackerel size at maturity was estimated for two areas: the Strait of Sicily and the Tyrrhenian Sea. All ovaries were assigned a reproductive phase based on macroscopic methods, and the reliability of this method (94%) was validated with a microscopic method (i.e., gonad histology). Although the collected females exhibited similar condition, in terms of total body weight at a given length, as well as similar gonad-somatic indices, the size at median maturity in the Strait of Sicily was smaller (161 mm total length [TL]) than in the Tyrrhenian Sea (176 mm TL). Future sampling in a series of years with contrasting levels of productivity may help identify whether this is a broad latitudinal trend, or due to specific oceanographic drivers, such as estuarine outflow into the Tyrrhenian Sea or upwelling in the Strait of Sicily. Meanwhile, resource assessments should consider that these two areas represent two phenotypic stocks. [ABSTRACT FROM AUTHOR]

The objective of the study was to describe the ovarian abnormalities of horse mackerel, Trachurus trachurus (Linnaeus, 1758), and to investigate the relationships that may exist between these abnormalities and nematode parasite infestation. 953 specimens of T. trachurus were randomly sampled between February 2013 and March 2014. A biometric analysis was conducted for every fish specimen. After dissection, parasites were collected, identified and the infestation rate was calculated. A macroscopic and microscopic study of the gonads was carried out for the infested and non infested fish specimens. The results revealed that only one ovary of the total sample examined had a morphological malformation. However, the microscopic study revealed that almost all the infested females had abnormalities: cyst and atresia increased for 17% and 38% of the examined subsample, respectively. The current results showed clearly that ovarian abnormalities were observed in large and old females, which were the most infested. [ABSTRACT FROM AUTHOR]

Three fishes of genus Scomberomorus (family: Scombridae) were observed among the catch of pelagic fish (Sardinella aurita, Sardinella maderensis, trachurus mediterraneus and Engraulis encrasicolus) obtained by pure seine net using light operated in the Egyptian Mediterranean waters (off Abu- Qir). Two fish were recorded for the first time of West African Spanish mackerel (Scombermorus tritor; Cuvier, 1832); the third was the migrated red sea species into the Mediterranean Sea (Scombermorus commerson; laceped, 1800). By comparing the morphometric characters of both species having the same length (TL: 41.0 cm.); it was found that they have the same meristic counts, but differing in about 10 morphometric indices out of 26, where Scombermorus commerson have greater values than Scombermorus tritor. Generally, the external features of the bodies of the two species are the main difference between them, as Scombermorus tritor have about 40 black rounded spots around the lateral line, while Scombermorus commerson have about 16 vertical bars below the first, and second dorsal fin followed by about twenty black rounded spots extended behind till caudal fin. [ABSTRACT FROM AUTHOR]

Abstract The synchrony of pelagic fish population dynamics with climate variability may impose significant alterations in their distribution and biomass, as well as catch composition, with potential effects on ecosystems and fisheries. This work examines the effect of the Atlantic Multidecadal Oscillation (AMO) and North Atlantic Oscillation (NAO) signals across the Mediterranean Sea sub-regions (western, central and eastern), with respect to small (European sardine Sardina pilchardus , European anchovy Engraulis encrasicolus , round sardinella Sardinella aurita and European sprat Sprattus sprattus) and medium (Atlantic mackerel Scomber scombrus , Atlantic chub mackerel Scomber japonicus , Atlantic horse mackerel Trachurus trachurus , Mediterranean horse mackerel Trachurus mediterraneus) pelagic fishes using various catch ratios and the mean temperature of the pelagic catch (MTpC) method for the period 1970–2014. The time until the pelagic fish communities react to the signals of the AMO and NAO, as revealed by the MTpC and catch ratios, varied among the Mediterranean sub-regions. The pelagic fishes of the central and eastern Mediterranean are those that responded most strongly to AMO variability, whereas those of the central and western Mediterranean also responded to the NAO. The effect of the NAO on pelagic fishes of the eastern Mediterranean was not significant. [ABSTRACT FROM AUTHOR]

Abstract Small pelagic fishes such as sardine and anchovy play an important role in marine ecosystem and are affected largely by environmental changes because of their character as r-strategists and their low trophic levels. Small pelagic fishes are crucial targets of Chinese fisheries, accounting for 26% of the total catch in 2014. Their catches show an increasing trend since the 1950s. However, there is still little information on small pelagic species inhabiting Chinese waters. Catch trends and impacts of climatic regime shifts for six typical commercially important small pelagic species, chub mackerel (Scomber japonicus), Japanese scad (Decapterus maruadsi), Pacific herring (Clupea pallasi), Japanese anchovy (Engraulis japonicus), Japanese sardine (Sardinops melanostictus) and horse mackerel (Trachurus japonicus), are analyzed using Chinese Fishery Statistics, FAO data, climatic indices and sea surface temperature (SST) data. The aim is to explore the interannual to decadal variability of their catches in China Seas and their responses to climatic regime shifts. Decadal variability is evident in the catches of the six small pelagic fishes with different variation patterns between warm- and cold-water species. Step changes in catches of the six species were observed in 1976/77, 1986/87, 1995/96, 2001/02 and 2005/06, while regime shifts in climatic/SST indices occurred around 1976/77, the late 1980s and the mid-1990s. This indicates that decadal variations in small pelagic fishes respond strongly to the climatic regime shifts, and the different response patterns of warm- and cold-water species reflect their different life strategies. Marine thermal variation patterns during the period 1981–2000 were well explained by different phase changes in the SSTs between summer and winter and were consistent with the step change in the catches of small pelagic fishes. The double-integration hypothesis, which indicates that cumulative integrations of atmospheric forcing can generate marine population responses, is useful both to understand the process from climate forcing to fish and the controlling mechanism of climate variability on small pelagic fishes in China Seas. [ABSTRACT FROM AUTHOR]

This study aimed to determine and compare proximate composition of three commonly commercial imported frozen fish species in Nigeria (Scromber scrombrus, Trachurus trachurus and Sardinella aurita) with reference to poor handling and size. Major nutrient compositions of raw muscles like protein, fat, moisture, ash were estimated. Fish samples were collected from importing fishing company in Lagos State (loading point) (location I) and three cold rooms in Ogun State (location II). Proximate analysis revealed that the protein, carbohydrate, lipid ash and fibre contents were high in the three species in the two locations even though nutrition quality of the three frozen fish samples obtained in the location I were higher than location II. The results revealed that the correlations between weights and proximate composition were relatively precise for moisture and protein, but were much more variable for lipid content, ash and crude fibre.

Status assessment of exploited fish populations is a general requirement to ensure sustainability of fisheries in both global and local contexts. The blue jack mackerel Trachurus picturatus (Bowdich, 1825) remains unassessed in a data-limited fishery in the eastern central Atlantic, within the waters of the Canary Islands (Spain) off the coast of northwest Africa. This is the most southwestern targeted fishery in the species' distributional range. To obtain basic life-history information, a total of 2 472 specimens were analysed, ranging from 10.2 to 31.9 cm total length, from samples collected monthly between March 2005 and March 2006. Length-weight relationships (a = 0.0023; b = 3.418; R2 = 0.97) showed no significant difference between sexes. Deposition periodicity and coherence of the ageing criteria were verified by analysis of the monthly evolution of the otolith edge. Ages were estimated by counting annual growth rings on whole otoliths, with these fish ranging from age 0 to 6 years. The von Bertalanffy growth model, which was used to estimate growth parameters from both direct readings and back-calculated length-at-age data, gave good statistical fits. The parameters from the direct readings were: L∞ = 34.9 cm; k = 0.214 y-1; t0 = −2.545 y (R2 = 0.84), and the natural mortality rates estimated from empirical methods varied between 0.20 and 0.55 y-1. [ABSTRACT FROM AUTHOR]

This study investigates the possible pathways for Pelagia noctiluca intrusions over the shelf to understand the interactions between jellyfish and fish larvae. To assess how the presence of P. noctiluca may influence populations of Engraulis encrasicolus and Trachurus trachurus , we analyzed the effect of environmental conditions on the abundance and spatial distribution of P. noctiluca , medusae and ephyrae, and early life stages of these two fish species along the Catalan coast. The highest concentrations of P. noctiluca were found offshore, all along the Northern Current path. Their occurrence over the shelf was associated with intrusions of open sea waters that contoured anticyclonic eddies generated by the oscillatory behaviour of the current. Anchovy larvae were found widely over the shelf, but were especially abundant in the north and in waters influenced by the Ebro river. Spatial patterns of anchovy larvae were defined better by physical environmental factors than by the presence of P. noctiluca , whose distribution clearly was determined by the circulation. The differences in environmental conditions controlling the populations of P. noctiluca and E. encrasicolus larvae prevent their general coexistence over the shelf and prey-predator interactions remained limited to the areas affected by offshore intrusions. It is remarkable that the occurrence of T. trachurus larvae and juveniles was limited to locations over the shelf where jellyfish were observed and never offshore. This suggests that the association between fish and jellyfish occur once jellyfish have been advected from offshore towards the shelf, favouring the survival of larvae and juveniles of T. trachurus . [ABSTRACT FROM AUTHOR]

Atlantic horse mackerel (Trachurus trachurus, Linnaeus, 1758) is a highly exploited species, common throughout the North‐East Atlantic. As a pelagic‐neritic fish it typically occurs over the shelf from the surface to 200 m deep on sandy bottoms. Most research has focused on distributions of adults or early life stages (eggs and larvae) of this species in offshore waters and only a few studies have reported the occurrence of early stages near the coast. However, these nearshore environments might be important for the early growth and survival of the Atlantic horse mackerel. In addition, little is known on how environmental processes might affect the early stages of this species. Here, we monitored weekly recruitment of horse mackerel to artificial substrates (SMURFS) deployed near the coast at both the surface and near the bottom, and back‐calculated hatching cohorts. The relationship of both recruitment and hatching patterns with environmental factors was investigated. From a total of 2,515 fish, 2,490 (99%) recruited to surface SMURFS. A GAM and GAMM analysis of the recruitment and hatching patterns, respectively, revealed a strong relationship with the lunar cycle and upwelling. Both recruitment and hatching showed lunar periodicity, with peaks near the new moon and revealed to be influenced negatively by upwelling. This study suggests that the nearshore environment might be an important nursery area for post‐larval and early juvenile Atlantic horse mackerel. [ABSTRACT FROM AUTHOR]

Models to predict codend size selectivity for four major commercial species—European hake (Merluccius merluccius), Norway lobster (Nephrops norvegicus), deep-water rose shrimp (Parapenaeus longirostris), and Atlantic horse mackerel (Trachurus trachurus)–in Mediterranean bottom trawl fisheries were established based on data collected during fishing trials using the two legal codends: a 40 mm square-mesh codend and a 50 mm diamond-mesh codend. The models were applied to predict the extent to which size selection depend on codend type, also accounting for the potential effect of codend catch size and fishing season. The size selectivity of the two codends was evaluated and compared in identical simulated controlled conditions. Mesh type significantly affected the size selection of Norway lobster alone, with a slightly better performance of the 40 mm square-mesh codend. A high risk of retention of undersized individuals was predicted for both codends for all species except Norway lobster. [ABSTRACT FROM AUTHOR]

Abstract: It is known that the formation of ice crystals has a negative impact on the flesh quality of frozen meat. This study focuses on how the formation of ice crystals in the dorsal ordinary muscle affects the flesh quality of frozen horse mackerel (Trachurus japonicus). Freeze‐thawed muscle specimens (F‐TMS) of horse mackerel were first stored at −24C and then thawed. The K‐value, expressible water, breaking strength of unfrozen muscle specimens (UMS) and F‐TMS, and histological structure (light microscope [LM], scanning electron microscope [SEM] of UMS, frozen muscle specimens [FMS], and F‐TMS) were investigated. K‐values were higher in the F‐TMS than in the UMS, and the increasing rate of K‐value in F‐TMS was approximately 1.4‐fold higher than UMS. Similarly, the percentage of expressible water was higher in the F‐TMS than in the UMS. The breaking strength of the UMS decreased with storage period, but it remained at a higher level than that of F‐TMS. Numerous ice crystal formations in muscle cells of FMS and small interstices between cells of F‐TMS were observed under LM. Moreover, we observed a relatively collapsed honeycomb structure of the extracellular matrix (ECM) under SEM, and found that collagen fibril networks of endomysiums became looser after thawing. Therefore, ice crystals contribute to vulnerabilities in the ECM. These results suggest that a decrease of freshness and the degradation of physical properties caused by ECM destruction may be due to the formation of ice crystals in muscle structures during freezing, leading to the deterioration of flesh quality during storage. Practical applications: The flesh quality deteriorated after thawing on the basis of degradation of physical properties. Moreover, it could be presumed that the K‐value increase was exacerbated by ice crystals, and the decreasing speed of chemical freshness was sped up accompanied by ice storage after thawing. Thus, the formation of ice crystals, which destroyed the muscle cells and structures, may be one of the dominant factors causing the deterioration in the flesh quality. [ABSTRACT FROM AUTHOR]

Trachurus trachurus and Trachurus mediterraneus play an important role in the marine ecosystem and represent an important source of income for local economies related to fishery. This study aimed to improve the knowledge on the spatial distribution and habitat requirements of these two horse mackerels in the south-central Mediterranean Sea (Strait of Sicily) by applying specie distribution models. Species’ biomass HotSpots, areas where the highest abundances are concentrated, were modelled as a function of physical and oceanographic parameters. Predictive distribution maps were produced to identify species-specific spatial patterns and possible overlapping in the distribution areas of the two congeneric species. Depth, bottom salinity, bottom sea temperature, sea surface temperature variation and slope were the main drivers for horse mackerels habitat suitability. Predictive distribution maps revealed a clear spatial segregation between biomass HotSpots of the two species, which depends on complex abiotic and biotic relationships. Since horse mackerels are the main component of discards produced by deep rose shrimp fishery in the Strait of Sicily and due to the importance of discard reduction in the current fishery policies, the results can provide important information for setting up spatial-based management strategies for the Strait of Sicily fisheries aimed in particular at minimizing unwanted by-catches. [ABSTRACT FROM AUTHOR]

Abstract: The presence of zoonotic Hysterothylacium larvae in fish from Spanish Atlantic and Mediterranean waters, which can cause economic losses for commercial fisheries, has been reported in several studies; however, little is known about species identity in this region. The aim of this study was to identify at species level the Hysterothylacium morphotypes detected in three commonly consumed fish: horse mackerel (Trachurus trachurus), blue whiting (Micromesistius poutassou) and anchovy (Engraulis encrasicolus). Third‐ and fourth‐stage Hysterothylacium larvae, as well as adults obtained from larval in vitro culture, were morphologically and molecularly identified by ITS1/ITS2 rDNA sequencing. Four Hysterothylacium morphotypes were detected. Genetic analysis showed that morphotypes VIII and IX were different larval stages of Hysterothylacium aduncum, which was supported by cultured adult species identification. Morphotypes III and IV were found to correspond to different developmental stages of another species of Hysterothylacium. As all larval types detected were morphologically indistinguishable from others previously reported yet showed clear genetic differences, they are referred here as new genotypes. This is the first time that ITS‐sequence data of various developmental stages of the same species, including adults, have been studied and compared, providing crucial knowledge for future studies on Hysterothylacium identification and biology. [ABSTRACT FROM AUTHOR]

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Atlantic horse mackerel is one of the most popular fish for North African consumers. Mackerel constitutes a common host for the Anisakis species of infective larvae (L3). A. pegreffii and A. pegreffii  ×  A. simplex (s.s.) hybrid genotype were identified using PCR-RFLP and entire ITS-DNA sequencing protocol. This research investigated the prevalence and mean intensity of A. pegreffii and its hybrid form in randomly collected mackerel samples throughout spring to summer seasons from the Libyan western coast. Briefly, 55 out of 240 (22.9%) fish samples were confirmed to be infected and the prevalence of A. pegreffii reached 22.08% with mean intensity of infection 29.13 ± 2.43 parasite/fish, while the prevalence of A. pegreffii × A. simplex (s.s.) hybrid genotype was 0.8% with mean intensity of infection 22 ± 0.85 parasite/fish. The prevalence of infection noticeably elevated during the summer season to reach 30.8%. Additionally, female fish samples were heavily infected as the mean intensity of infection was 34.75 ± 1.27 parasite/fish. Furthermore, results indicated that the highest intensity of infection was recorded in older and female mackerel. To sum up, the current study has provided substantial information about the impacts, diversity and epidemiology of A. pegreffii and its hybrid form in North African waters. [ABSTRACT FROM AUTHOR]

Seaweeds have attracted an increasing attention as a new source for bioactive compounds, these include preservative compounds. This study is a first attempt to employ alga Cystoseira compressa for the preservation of chilled fish. For it, a combined ethanol-aqueous extract of this alga was included in the icing system and employed as chilling medium for the storage of horse mackerel ( Trachurus trachurus) for 11 days. On the basis of the microbial groups (aerobes, psychrotrophs, proteolytic, lipolytic and Enterobacteriaceae bacteria) assessed, an inhibitory effect ( p < 0.05) on microbial activity in horse mackerel muscle was observed as a result of including the alga extract in the icing medium; such preservative effect was also proved by chemical determinations related to microbial activity (pH and trimethylamine values). Additionally, a significant decrease ( p < 0.05) of lipid hydrolysis (free fatty acids formation) and oxidation (fluorescent compounds formation) in fish was also observed as a result of the presence of C. compressa extracts in the icing medium. The icing medium proposed in this work (i.e., the combination of ethanolic and aqueous extracts of C. compressa) may constitute a promising strategy to the application of natural algae extracts for fatty fish storage and enhance quality retention during commercialisation. [ABSTRACT FROM AUTHOR]

Lipid oxidation is a very complex and important event causing quality loss of foods, especially those containing highly unsaturated fats. There is growing interest in replacing synthetic antioxidants in food by natural counterparts. Olive leaf is an abundant by-product of the olive oil industry. The aim of this study was to investigate the antioxidant capacity of olive leaf powder (OLP) in minced Atlantic horse mackerel stored at 4 °C over 3 days. OLP was introduced in the minced at concentrations of 0 (control), 1.5, 3.5, and 4.5%. OLP characterization showed high antioxidant capacity and fiber content. The addition of OLP significantly prevented and delayed minced fish oxidation over storage. The antioxidant effectiveness of OLP was concentration-dependent, as observed in all the parameters analyzed. The results showed OLP as a potential natural antioxidant for fish products. Practical applications Olive leaves are an important agrifood by-product produced worldwide. This by-product is valorized for the first time, as far as the authors are aware, as natural antioxidant in fish. Olive leaves are rich in polyphenols (principally oleuropein) and α-tocopherol. Consumers may benefit from this research as there is an increasing demand for natural ingredients, along with concern about the environmental effects of food production. The results of the present study suggest that olive leaf powder can be successfully employed as natural ingredient to prevent oxidation in chilled horse mackerel mince. This allows transforming this by-product stream into a commercially valuable antioxidant. [ABSTRACT FROM AUTHOR]

The Atlantic horse mackerel, Trachurus trachurus, is a commercially important species whose daily spawning dynamics are not yet fully understood. Existence of spawning synchronicity would facilitate application of the daily egg production method for estimating the spawning biomass of the southern stock of the species in the Northeast Atlantic. The intent of this work was to study preovulatory follicle (PREF) growth dynamics in wild Atlantic horse mackerel to determine the existence of daily spawning synchronicity in the population. The size and translucency of hydrated oocytes increased significantly between early morning and late afternoon; this pattern was the same for two study years. This morpho-developmental shift led to the appearance of previously indistinguishable oil drops in ovarian whole mounts which is an easily observed microscopic descriptor of PREF growth. The results clearly suggested that PREF growth was well synchronized between Atlantic horse mackerel that were capable of spawning and provided evidence for the existence of daily spawning synchronicity in the population. Apart from sampling time of day, the size of hydrated oocytes was shown to be affected by body size: a 10 cm difference in maternal length corresponded to a 0.030mm difference in the diameter of hydrated oocytes. In contrast, the size of early germinal vesicle migration oocytes was correlated neither to sampling time nor to maternal size which suggests that the abrupt increase in PREF size only commences after the onset of the actively spawning sub-phase. [ABSTRACT FROM AUTHOR]

We determined high pressure processing (HPP) effects on the activities of cathepsins B and D in the muscles of mackerel (Scomber scombrus) and horse mackerel (Trachurus trachurus). In mackerel, the cathepsin B activity decrease reached 40% at 450 MPa while in horse mackerel, low and intermediate pressures (150 and 300 MPa) caused an activity increase (30%) but at 450 MPa a decrease of up to 60%. In both species, cathepsin D activity increased after a 300 MPa treatment (up to 2-fold for mackerel and 60% for horse mackerel) and decreased on a 450 MPa treatment. The activity increase is probably due to HPP damage of lysosome releasing enzymes into the fish muscle. Based on the HPP effects on the activities of cathepsins B and D, 450 MPa may be used to reduce the proteolytic activity of cathepsin B prior to chilled or frozen storage of these fish species.