Species Trachurus Research Articles

The complete mitochondrial genome of Chilean Jack Mackerel, Trachurus murphyi Nichols, 1920 (Teleostei, Carangidae)

The Chilean jack mackerel (Trachurus murphyi, Nichols, 1920) is a pelagic fish of high fishery interest, with a global capture of 828,358 mt in 2021. We report the complete mitochondrial genome of T. murphyi (Teleostei, Carangidae), collected in Bahia de Zapallar, Chile (32°33’02.59’’ S, 71°27’55.38’’ W). The size of the mitogenome is 16,561 bp (H-strand composition: 25.9% A, 16.7% C, 29.8% G, and 27.5% T). The mitogenome has the classic vertebrate gene content of 13 protein-coding, two rRNA, and 22 tRNA genes, as found in Carangidae and other Teleostei families. Phylogenetic analysis using mitochondrial genomes of 22 related species revealed that T. murphyi formed a well-supported monophyletic group with the other Trachurus species, being T. simmetricus its closest relative. Sequencing the mitochondrial genome from T. murphyi is the first step in developing traceability tools based on DNA analysis to enforce fishing quotas and trace the processed food and foodstuff containing Chilean jack mackerel following the objective of the South Pacific Regional Fisheries Management Organization (SPRFMO).

Resource Partitioning among "Ancillary" Pelagic Fishes (Scomber spp., Trachurus spp.) in the Adriatic Sea.

The Mediterranean is one of the most overfished seas of the world where mesopredators are severely threatened. The trophic strategies of four pelagic species that inhabit the Adriatic Sea (Scomber spp. and Trachurus spp.) were investigated through an integrated approach of stomach contents and stable isotopes analyses. Our study demonstrated that Scomber colias feeds mainly on strictly pelagic prey, with fish larvae as a secondary prey in the Southern Adriatic Sea, while S. scombrus feeds on prey belonging to higher trophic levels. Smaller specimens of Trachurus mediterraneus have a diet mainly based on pelagic prey, while larger fishes rely on prey such as benthic decapods, showing an ontogenetic shift in the diet of the species. Trachurus trachurus shows a preference for offshore and deeper areas and a diet such as that of its congeneric, but no clear ontogenetic shift was observed. This spatial segregation allows the co-existence of these two species of Trachurus. Scomber colias mainly inhabits southern areas and S. scombrus shows a preference for the northern sectors. This latitudinal gradient avoids the overlap of their trophic niches. Bayesian mixing models confirmed that the trophic niches of these species only partially overlap in the middle of the trophic web.

Ingestion of microplastics and mesoplastics by Trachurus declivis (Jenyns, 1841) retrieved from the food of the Australasian gannet Morus serrator: First documented report from New Zealand

During the process of studying some morphological characters of fish found in the food of the Australasian gannet Morus serrator breeding at Horuhoru Rock and Mahuki islands in the Hauraki Gulf, New Zealand, one carangid specimen of fish species Trachurus declivis out of the 25 fish specimens examined revealed seven small plastic particles in its stomach of different colours: black, red, blue, green, and transparent. Fourier transform infrared (FTIR) spectroscopy was used to identify the compositions of the particles as low and high density polyethylene, poly (methyl methacrylate), polypropylene, and a copolymer of butadiene, acrylonitrile, and methacrylamide. The plastic particles comprised several different shapes and sizes, ranging between 4.5 and 10 mm, and are therefore categorized as micro-and mesoplastic fragments.

Data-limited stock assessment of two horse mackerel species (Trachurus mediterraneus and T. trachurus) from the Mediterranean coast of Turkey

A preliminary assessment of stock size and status of Trachurus mediterraneus and T. trachurus species were investigated via virtual population and yield prediction analyses using onboard collected length-frequency data from Northeastern Mediterranean. The length-frequency based VBGF parameters and growth performance index were L∞=28 cm, k=0.62, t0=0.58, tanc=0.52 and Φ′=2.69 for T. mediterraneus and L∞=27.46 cm, k=0.54, t0=0.49, tanc=0.41 and Φ′=2.61 for T. trachurus. Trawl-type selectivity and maturity ogives were 16.73 and 19.2 cm TL for T. mediterraneus, and 17.59 and 19.8 cm TL for T. trachurus, respectively. The virtual population analysis of T. mediterraneus resulted that the minimum and maximum fishing mortalities were 0.02 and 1.09 yr −1 for the mid-length groups for 10.5 and 24.5 cm, respectively. The minimum and maximum fishing mortality of T. trachurus were 0.0 and 0.89 yr −1 at the size of 25.5 and 27.5 cm, respectively. Biological reference points of T. mediterraneus point out that the current fishing mortality (FCurr=1.62) is lower than the fishing mortality of FMSY, and the current exploitation rate (ECurr=0.63) is lower than the reference point target benchmarks E0.5 and EMSY, showing underexploited status. The current fishing mortality (FCurr=0.76) in T. trachurus was observed to be lower than the fishing mortality for the MSY (FMSY), and the current exploitation rate (ECurr=0.46) was lower than E0.5 and EMSY, indicating currently underemployed status.

The growth and age structure of Chilean jack mackerel (Trachurus murphyi) following its influx to New Zealand waters

The Chilean jack mackerel (Trachurus murphyi) is a predominantly Southeast Pacific Ocean species. It is relatively difficult to determine its age, and multiple studies of its growth off South America have produced markedly different sets of von Bertalanffy parameters. T. murphyi was first identified from New Zealand waters in the mid-1980s and has comprised part of the commercial landings of Trachurus species (along with Trachurus declivis and Trachurus novaezelandiae) since then. Results from 13 years of age determination of New Zealand samples using sectioned otoliths indicate that a partially validated age determination method has been developed, with a precision level (average percentage error) of 4.6%. The best available von Bertalanffy growth parameters for the New Zealand population (sexes combined) are as follows: L∞ , 51.9 cm fork length; K, 0.223 per year; t0 , -0.5 year. Analyses by sex showed that males have a significantly larger L∞ than females. Estimated annual catch-at-length and catch-at-age distributions from the fishery are presented for 2007-2019. There have been at least two episodes of immigration of T. murphyi from international waters, but little evidence of spawning success to maintain the New Zealand population.

Comparative study of esterase activities in different tissues of marine fish species Trachurus trachurus, Merluccius merluccius and Trisopterus luscus

Pesticides are one of the most frequently anthropogenic xenobiotics detected in water. Among these, the organophosphorus pesticides (OPs) are very widely used in agriculture due to their broad spectrum of activity and their low price, but they also have high potent effects as neurotoxic compounds in non-target organisms. The aim of this study was to evaluate biomarkers acetylcholinesterase (AChE), butyrylcholinesterase (BChE), propionylcholinesterase (PChE) and carboxylesterase (CbE) in the representative Atlantic fish species Trachurus trachurus, Merluccius merluccius and Trisopterus luscus from “Rías Gallegas”, a traditional Spanish fishing area. These esterase activities were evaluated in the brain, muscle and liver to determine the most adequate tissue to measure such enzymatic activities. The sensitivity of AChE and CbE activities from different tissues the widely used organophosphorus insecticide chlorpyrifos (CP), and its toxic metabolite (CP-oxon) was also tested. AChE activity was predominant in all tissues of the analysed species (particularly in brain constituting from 78.33%, 89.83% and 88.43% of total ChEs in Trachurus trachurus, Merluccius merluccius and Trisopterus luscus, respectively). Under in vitro exposure, esterases were shown to be highly sensitive to CP and especially to CP-oxon. Moreover, a similar effect observed on AChE and CbE activities could suggest that CbE activity might contribute efficiently against the toxic effects of CP, especially in muscle and the liver. The presence of BChE, PChE and upper CbE activities in muscle and the liver and their OP-sensibilities can be used to study their function in the pesticide biochemical detoxification pathways with a prominent role as a safeguarding mechanism against pesticide toxicity.

The Taxonomic Status and Intraspecific Differentiation of the Black Sea Horse Mackerel, Trachurus mediterraneus ponticus (Aleev, 1956) (Carangidae)

The taxonomic status of the horse mackerel, Trachurus mediterraneus ponticus (Aleev, 1956), which inhabits the Black Sea, has been clarified based on the analysis of variation in the nucleotide sequence of the mtDNA cytochrome b (Cyt-b) locus. A comparison of this species with the horse mackerel from the Mediterranean basin and the World Ocean has shown that the Black Sea horse mackerel is neither an independent species nor a subspecies and can only be qualified as the species Trachurus mediterraneus (Steindachner, 1868) distributed throughout the Mediterranean Sea basin. A hypothesis has been made about the possible cause of the origin and existence of two forms, “large” and “small”, of the horse mackerel. By using the technique of calculating ontogenetic trajectories, it has been found that these are two morpho-ecological forms, whose differentiation is most likely determined by the type of feeding.

Age structure and growth of the rough scad, Trachurus lathami (Teleostei: Carangidae), in the Southeastern Brazilian Bight

ABSTRACT The rough scad, Trachurus lathami Nichols, 1920, is a small pelagic species distributed along the West Atlantic coast. It is most abundant in the Southern Brazil (28°30’-34°S) and in the Southeastern Brazilian Bight (SEBB, 22°-28°30’S). The rough scad is fished by purse seines, which main target is the Brazilian sardine, Sardinella brasiliensis (Steindachner, 1879). Age and growth are vital to understand the life cycle of a species, to fishery management and ecosystem modeling. This study aimed to assess the age and growth of T. lathami, to identify its age structure in the SEBB, and to evaluate what causes the wide differences among Trachurus species in terms of body size and growth parameters. Data available on T. lathami was attained between 2008 and 2010 from surveys at SEBB. A total of 278 whole otoliths of T. lathami, total length between 27 mm and 208 mm, were analyzed and compared with the only other source of otolith data, from 1975. Three blind readings were performed and assessed using traditional methods to study fish age and growth. Zero up to eight rings were found, each ring corresponding to one year in the life of an individual of this species. The von Bertalanffy growth model parameters were L∞ = 211.90 mm and K = 0.319 year-1. The results of the analyses have shown similarities between 1975 and 2008-2010, indicating that the otolith development, the growth pattern and the age structure remained stable. T. lathami is the smallest species of Trachurus and it has the highest growth rates among them. This is probably related to the different temperatures where larvae/juvenile and adult grow, to the absence of a strong fishing pressure and to decadal population variability.

Employing DNA barcoding as taxonomy and conservation tools for fish species censuses at the southeastern Mediterranean, a hot-spot area for biological invasion

This study evaluates the utility of DNA barcoding (mitochondrial cytochrome oxidase subunit I; COI) as a biodiversity and conservation applied tool for identifying fish fauna from the southeastern Mediterranean (the continental coast of Israel), a hot-spot area for biological invasion, also with an eye to establish the foundation for follow-up studies that will use environmental DNA (eDNA) tracks of native and invasive species, and for the application of eDNA concepts and methodologies in nature conservation. We established a dataset of 280 DNA barcodes, representing 110 marine fish species (all identified by a taxonomist), belonging to 75 native and 35 Lessepsian migratory species that were tested within and against the BOLD system database. Most of the query sequences showed 98% matches with reference DNA barcodes in the BOLD system excluding two Trachurus species, three Dasyatis pastinaca and two Rhinobatos rhinobatos individuals. Relatively high intraspecific genetic distances were observed in two Elasmobranchii species (8.83%–18%), suggesting possible cryptic species. In contrast, relatively low interspecific genetic distances were found between two Actinopterygii species (1.54%). Gobiidae family members were observed as being the most scattered on the Bayesian tree. Out of the 110 fish species, 48 were taxonomically discordant with the BOLD BINs (4 at the family level, 15 at the genus level and 29 at the species level), 53 were concordant and 9 were singletons. Discordancy was noted for some Diplodus and Fistularia species during the BOLD BIN analysis. Apogon queketti, Champsodon nudivittis and Cheilodipterus novemstriatus were uploaded to the BOLD system for the first time. We elucidated 177 haplotypes, 122 for the native fish species and 55 for the Lessepsian species. The results will allow the evaluation of invasive species success and will help developing improved policies for the conservation of Mediterranean biodiversity.

Impact of environmental factors on recruitment and hatching patterns of Horse Mackerel (L.) collected in a nearshore rocky reef system

Event Abstract Back to Event Impact of environmental factors on recruitment and hatching patterns of Horse Mackerel (L.) collected in a nearshore rocky reef system Maria Klein1, 2*, Elisabeth Van Beveren1, 3, Diana Rodrigues2, Emanuel J. Gonçalves2, Ester A. Serrão1 and Rita Borges1, 2 1 Centre of Marine Sciences, Portugal 2 MARE - Marine and Environmental Sciences Centre, ISPA – Instituto Universitário, Portugal 3 IFREMER (Institut Français de Recherche pour l’Exploitation de la MER), CRH, Research Unit EME (UMR 212), France Horse mackerel (Trachurus trachurus, Linnaeus, 1758) is a highly exploited fish species, common throughout the North-East Atlantic. As a pelagic-neritic fish it typically occurs over the shelf at 100-200 m depth on sandy bottom and most research has focused on adults or early life stages (eggs and larvae), caught or examined in deeper waters. Nevertheless, larvae and early stages of Trachurus species have been observed in the nearshore environment of a rocky reef system in Portugal. More research is needed in order to understand the importance of nearshore environments for horse mackerel. In addition little is known on how environmental processes might affect early life parameters of this species. In this study we monitored the arrival of early juvenile horse mackerel to the reef environment at a fine time scale, and analyzed the relationship of environmental factors with patterns of recruitment and hatching, revealed by otolith microstructure analysis. In total around 2500 fish were collected with Standard Monitoring Units for the Recruitment of Fish (SMURF) and a distinct depth preference was recorded as 99% of fish were sampled with surface SMURFs. A GAM and GAMM analysis of the recruitment and hatching pattern, respectively, revealed a strong relationship with the lunar cycle and local up-welling. Both recruitment and hatching had a periodic pattern with peaks near the new moon; upwelling had a negative impact. Further, the study indicated that the nearshore environment might be an important nursery area for the post-larval growth of horse mackerel. Keywords: Trachurus trachurus, Lunar pattern, upwelling, juvenile, cohort, generalized additive models Conference: XV European Congress of Ichthyology, Porto, Portugal, 7 Sep - 11 Sep, 2015. Presentation Type: Oral Presentation Topic: Otoliths as a tool to study fish life cycles Citation: Klein M, Van Beveren E, Rodrigues D, Gonçalves EJ, Serrão EA and Borges R (2015). Impact of environmental factors on recruitment and hatching patterns of Horse Mackerel (L.) collected in a nearshore rocky reef system. Front. Mar. Sci. Conference Abstract: XV European Congress of Ichthyology. doi: 10.3389/conf.fmars.2015.03.00066 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 11 Nov 2015; Published Online: 11 Nov 2015. * Correspondence: Ms. Maria Klein, Centre of Marine Sciences, Faro, 8005-139, Portugal, mariaklein55@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Maria Klein Elisabeth Van Beveren Diana Rodrigues Emanuel J Gonçalves Ester A Serrão Rita Borges Google Maria Klein Elisabeth Van Beveren Diana Rodrigues Emanuel J Gonçalves Ester A Serrão Rita Borges Google Scholar Maria Klein Elisabeth Van Beveren Diana Rodrigues Emanuel J Gonçalves Ester A Serrão Rita Borges PubMed Maria Klein Elisabeth Van Beveren Diana Rodrigues Emanuel J Gonçalves Ester A Serrão Rita Borges Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

The first report of liver coccidian Goussia cruciata in jack mackerel, Trachurus murphyi, from the South Pacific and its relationship with host variables.

The liver coccidian Goussia cruciata is considered as a specific parasite of the genus Trachurus, but to date, this parasite has only been reported for Atlantic species (Trachurus picturatus, Trachurus lathami, Trachurus trachurus and Trachurus mediterraneus). Therefore, this is the first report of this parasite in a species of Trachurus from the South Pacific. The prevalence and abundance of this coccidian in jack mackerel, T. murphyi, was determined, and its relationships with host variables such as total body length, condition factor and hepatosomatic index were evaluated. A total of 49 individuals were sampled from a commercial vessel of the central Chilean coast (36° 41' S, 73° 06' W) in November 2013 and February and May 2014. The parasite was identified by means of liver smears using light microscopy. The relationship between the abundance of the parasites and the host total length, condition factor and hepatosomatic index was analysed with Spearman's correlations. The sporogonic stages exhibited sporocysts that were morphologically concordant with coccidian G. cruciata. All hosts were parasitised with this coccidian, and the abundance varied between 2 and 224 oocytes per host. The parasite abundance was negatively correlated with the host total length. Infection levels of G. cruciata in T. murphyi apparently do not produce negative effects on fish condition.

Assessment of metal concentrations in commercially important fish species in Black Sea

In the present study, concentrations of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) were measured in the muscle, gill, and gonads of the pelagic fish species Trachurus mediterraneus, Engraulis encrasicolus ponticus, and Sprattus sprattus that are important both commercially and for the ecosystems in the Black Sea. The samples were collected during 2011. The metals were determined using inductively coupled plasma mass spectrometry (ICP-MS) following an acid digestion. The highest concentrations of As, Cd, Co, Cr, Cu, Pb, and Zn were found in E. encrasicolus ponticus, whereas the greatest concentrations of Ni were found in T. mediterraneus and Mn in S. sprattus. Results showed that average metal concentrations in the tissues of T. mediterraneus, E. encrasicolus ponticus, and S. sprattus decreased in the order gill > gonad > muscle, gonad > gill > muscle, and gill > gonad > muscle, respectively, for the three species. When metal concentrations of fish tissues were compared between fish gender, there were only statistical differences in the gonads of the studied fish species (p < 0.05). The present study demonstrated that the metals have different correlations with condition factor (CF) and gonadosomatic index (GSI) of the fish species. Cr showed statistically important positive correlation to the GSI in male T. mediterraneus. Co showed statistically important positive correlation to CF in female E. encrasicolus ponticus, and also Co and Cd showed correlation to CF in male T. mediterraneus. Cd concentrations in the muscle tissues of the fish species were above the maximum acceptable concentration for human consumption.

Energy demand of larval and juvenile Cape horse mackerels, Trachurus capensis, and indications of hypoxia tolerance as benefit in a changing environment

Trachurus capensis is an important fisheries resource in the degraded Namibian upwelling ecosystem. Food supply and shoaling of hypoxic zones are hypothesised to influence the species’ recruitment success. This paper is the first to quantify energy requirements and hypoxia tolerance of larval and juvenile stages of a Trachurus species. We measured normoxic respiration rates of T. capensis with a size range from 0.001 to 20.8 g wet mass (WM) collected off Cape Town (33.9°S, 18.5°E, 12/2009) and in the northern Benguela (17–24°S, 11–15°E, 02/2011). Routine metabolic rate (RMR) and standard routine rate (SRR) (mg O2 h−1) followed the allometric functions RMR = 0.418 WM0.774 and SRR = 0.275 WM0.855, respectively. Larvae and juveniles had comparatively high metabolic rates, and the energy demand of juveniles at the upper end of the size range appeared too high to be fuelled by a copepod diet alone. T. capensis’ early life stages showed a high tolerance to hypoxic conditions. RMR in larvae did not change until 30 % O2sat at 18 °C. In juveniles, critical oxygen saturation levels were low (PC for SRR = 11.2 ± 1.7 % O2sat and PC for RMR = 13.2 ± 1.6 % O2sat at 20 °C) and oxy-regulation effective (regulation index = 0.78 ± 0.09). A high hypoxia tolerance may facilitate the retention of larvae in near-shore waters providing favourable feeding conditions and allowing juveniles to exploit food resources in the oxygen minimum zone. These mechanisms seem to well adapt T. capensis to a habitat affected by spreading hypoxic zones and probably enhance its recruitment success.

Composition and daytime vertical distribution of the ichthyoplankton assemblage in the Central Cantabrian Sea shelf, during summer: An Eulerian study

During summer, wind driven coastal upwelling dominates in the Central Cantabrian Sea (southern Bay of Biscay). Nevertheless, atmospheric forcing is highly variable and wind pulses may cause noticeable and fast hydrographic responses in the shelf region. In this paper, the composition and vertical distribution of the summer ichthyoplankton assemblage during the daytime at a fixed station, located on the Central Cantabrian Sea shelf, are documented. Also, the impact of a short-time scale hydrographic event on the abundance and structure of the larval fish assemblage is examined. Significant small-scale temporal hydrographic variability was observed. Currents showed changes in speed and direction and significant changes in thermocline depth were also observed. A total of 34 taxa of fish larvae were identified. Engraulis encrasicolus eggs and larvae of the shelf-dwelling species Trachurus trachurus, Capros aper and E. encrasicolus dominated the ichthyoplankton assemblage. The distribution of E. encrasicolus eggs and fish larvae was vertically structured. E. encrasicolus egg concentration increased exponentially towards the surface. Fish larvae showed a subsurface peak of concentration and their vertical distribution was not conditioned by thermocline depths. The short term hydrographic event did not affect the vertical distribution of fish larvae but it accounted for significant temporal changes in larval fish assemblage structure and abundance. Results suggest that temperature and light intensity are important factors in the vertical distribution of fish larvae. They also indicate that the temporal monitoring of the larval fish assemblage in this region requires multiple sampling sites.

Multivariate Discrimination among Three Trachurus Species from Turkey

Multivariate Discrimination among Three Trachurus Species from Turkey

Demersal fish assemblages off the Seine and Sedlo seamounts (northeast Atlantic)

Abstract Seamounts are thought to support special biological communities, and often maintain high standing stocks of demersal and benthopelagic fishes. Seamount fish fauna have been described in several studies but few works have included species taken below 600 m. The demersal fish assemblages of the Seine and Sedlo seamounts (northeast Atlantic) from the summits to 2000 m depth were investigated based on longline survey catch data, conducted as part of the OASIS project. A total of 41 fish species from 24 families were caught at Seine near Madeira, and 30 species from 19 families were caught at Sedlo north of the Azores. Both fish faunas have high affinities with the neighbouring areas of the Azores, Madeira and with the eastern North Atlantic and the Mediterranean Sea. Overall abundances and mean body weights were slightly higher at Sedlo seamount, appearing in conformity with the latitudinal effect of increasing species abundance and productivity from south to north. The differential influence of the Mediterranean Water at each seamount may contribute to explain (a) the differences found in vertical distribution of common species, which tend to distribute deeper at Seine, and (b) the observed changes in the species composition and dominance in deeper waters. Multivariate analysis revealed a vertical structure that is approximately coincident with the expected zonation of water masses at each seamount. Physiological tolerance to the prevailing vertical hydrological conditions may explain the species distribution and the large-scale vertical assemblage structure found. However, further ecological factors like productivity patterns affecting the amount and quality of the available food appear to shape the abundance, diversity or dominance patterns of functional groups within those main assemblages. At Seine, the species Trachurus picturatus dominated the catches, mainly at the shallower edge of the plateau, appearing consistent with the sound-scattering layer interception hypothesis [Isaacs, J.D., Schwartzlose, R.A., 1965. Migrant sound scatterers: interaction with the sea floor. Science 150, 1810–1813]. At both seamounts mesopelagic feeders (e.g., Beryx splendens) dominate the upper-slope assemblages ( 1300 m) were dominated by squaliform species (e.g., Centrophorus squamosus, Centroscymnus coelolepis, Etmopterus princeps) along with Mora moro or the Antimora rostrata. The lower abundance of C. squamosus observed at Seine may be a result of the fishing activities in the area, since the species is an important by-catch of the black-scabbard fish fishery in the Madeira archipelago. The slightly higher predominance of scavenger species at Seine in deeper assemblages may be the result of an ecological response favouring this functional group in lower productivity regimes. Especially relevant was the record of large reproductive aggregations of B. splendens and Epigonus telescopus found at the edge of the Sedlo plateau.

Molecular phylogeny of Turkish Trachurus species (Perciformes: Carangidae) inferred from mitochondrial DNA analyses

Genetic variation among three species of Trachurus (T. trachurus, T. mediterraneus and T. picturatus) from Turkey was investigated by phylogenetic analysis of the entire mtDNA control region (CR) (862 bp, n = 182) and partial cytochrome (cyt) b (239 bp, n = 174) sequences. Individuals were collected at nine stations in four geographic locations: North‐eastern Mediterranean Sea, Aegean Sea, Sea of Marmara and Black Sea. Polymerase chain reaction‐direct sequencing of the CR and the partial cyt b genes produced 28 and 131 distinct haplotypes, respectively. Maximum likelihood, neighbour‐joining and maximum parsimony methods produced similar tree topologies. The results of both CR and cyt b sequence analyses revealed the existence of several species‐specific nucleotide sites that can be used to discriminate between the three species. Genetic distances indicated that T. mediterraneus and T. picturatus are more closely related to each other than either is to T. trachurus. Inter‐nucleotide and intra‐nucleotide diversities of T. picturatus were larger than those of T. mediterraneus and T. trachurus. There was no evidence of a geographical difference in haplotype frequencies of these two mtDNA regions to be clustered.

Complete mitochondrial DNA sequence of Atlantic horse mackerel Trachurus trachurus and molecular identification of two commercially important species T.�trachurus and T.�japonicus using PCR-RFLP

To characterize and identify mitochondrial DNA (mtDNA) nucleotide sequence variation in two commercially important Trachurus species, Trachurus trachurus and T. japonicus, the complete mtDNA sequence of T. trachurus was determined. The T. trachurus mtDNA consists of 16 559 bp, containing 22 transfer RNA (tRNA) genes, two rRNA genes, and 13, protein-coding genes. Comparing the mtDNA nucleotide sequences of the Trachurus species, a polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP) method was developed to differentiate these two commercially important species. The primer pair Lt1-ND5 and Ht1-ND5, corresponding to ND5, was designed to amplify a 360-bp fragment. Following digestion with Eco RI, the PCR product for T. japonicus resulted in 93- and 267-bp fragments, while T. trachurus lacked a restriction site for Eco RI. In contrast, after digestion with Hin fl, the T. trachurus PCR product yielded 44-, 84-, and 232-bp fragments, while the T. japonicus product was not digested. The PCR-RFLP analysis established in the present study was useful for identifying T. trachurus and T. japonicus.

Shallow genetic structure of 3 species of the genus Trachurus in European waters

Pelagic marine fishes generally show little geographical population differentiation. Of special interest are marine species with Atlantic-Mediterranean distribution because of the possible effect of past and present day restrictions to gene flow between the 2 seas. Thus, restriction analysis of the whole control region (D-loop) of mitochondrial DNA (mtDNA) was used to extensively investi- gate the genetic structure of the 3 Trachurus species present both in Atlantic and Mediterranean waters: T. trachurus, T. mediterraneus and T. picturatus. In total, 666 individuals were screened from 5 Mediterranean and 6 Atlantic areas. Two African areas were also sampled for T. trachurus. No dif- ferentiation was revealed among European populations within the 3 studied species. Additionally, no sign of Atlantic-Mediterranean division was found, probably due to the fact that specific life history traits provide the Trachurus species with flexibility to oceanographical constraints and give them the ability to migrate long distances. Differentiation was only revealed between European and African populations of T. trachurus, reinforcing the existence of the T. trachurus capensis subspecies in African waters. Populations are probably under long and stable demographic equilibrium conditions as indicated by high haplotypic and nucleotide diversity values for all 3 species. Thus, mtDNA could be a powerful tool in determining the taxonomic distinctiveness of individual populations and spe- cies, and therefore, aid in setting priorities for future management policies. The present results are also discussed in comparison with the results of previous cytochrome b sequence analysis of the 3 Trachurus species.

Genetic Identification and Phylogeny of Three Species of the Genus Trachurus Based on Mitochondrial DNA Analysis

The genetic identification and the phylogenetic relationships of 3 European species of the genus Trachurus (T. trachurus, T. mediterraneus, and T. picturatus) across their geographical distribution, have been investigated by mitochondrial DNA analysis. Both cytochrome b and 16S ribosomal DNA sequence analysis revealed the existence of several species-specific positions that distinguish the 3 studied species. Genetic distances between the species indicated that T. mediterraneus and T. picturatus are more closely related than T. trachurus. Similar topologies have been produced by neighbor-joining, maximum-likelihood, and maximum-parsimony trees, and they were in accordance with previous taxonomic classification. Internucleotide and intranucleotide diversity of T. picturatus was 2 times higher than that of T. mediterraneus and T. trachurus, possibly owing to the low levels of fishing pressure for T. picturatus. This is the first report of the phylogenetic relationships of the 3 Trachurus species and provides a possible scenario of the time of divergence related to the closure of the Gibraltar Straits. In addition, the present results can be used for genetic identification of the 3 species, even from the early stage of eggs, and for detection of commercial fraud.