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Otolith shape analysis has been extensively employed to distinguish stocks and populations of marine fish species. While the majority of studies have employed Elliptic Fourier descriptors (EFD) for this purpose, an alternative approach was introduced in 2005 founded on the Wavelet Transform, using the à trous multiscale signal representation with a B3-Spline function. This approach not only improved the biological and mathematical interpretation but also empowered the user to select a more suitable level based on the contour complexity. Recently, the global adoption of the mathematical R environment enabled the creation of a freely accessible package called shapeR for otolith shape analysis using Daubechies least-asymmetric wavelet. Nevertheless, we have pinpointed certain inconsistencies in this package concerning the biological implications of its results and a deviation from the original application philosophy. To illustrate these inconsistencies, we conducted a study aiming to differentiate populations and morphotypes of the blue jack mackerel, Trachurus picturatus, from the Canary Islands and Madeira. We employed both shapeR package and our original method in the comparison. Furthermore, we evaluated the performance of different parametric and non-parametric classification algorithms using wavelet coefficients obtained from both methodologies. This study has shown that both methods are suitable for population identification, achieving high classification accuracy. However, some inconsistencies were observed between the graphical representation of the intraclass correlation plot and the mean otolith contour reconstruction using the shapeR package. AFORO demonstrates a particular strength in capturing morphological changes, allowing for better identification of contour shape variations along the wavelet signal. Additionally, both methods identified the same number of morphotypes within the overall sample, albeit with differing proportions. [ABSTRACT FROM AUTHOR]

To implement the Marine Strategy Framework Directive (MSFD) of the European Union (EU) in order to achieve the Sustainable Development Goals (SDGs) of the United Nations (UN) regarding the biological sustainability of marine fisheries, it is fundamental to apply a framework for prioritizing stocks. This process helps the regional managers to make the best use of data and resources for management. The present study describes and applies a standard framework for prioritization of stock assessment in the Azores. The current state of the selected stocks is identified and the main issues and gaps for assessment are presented and discussed. A total of 138 species were landed in the region during the period 2009-2019. Twenty-two (18 fishes, 2 molluscs and 2 crustaceans) were selected as priority stocks according to the Food and Agriculture Organization of the United Nations (FAO) and International Council for the Exploration of the Sea (ICES) criteria. Most of these showed a decreasing trend in their abundances. Only four stocks are currently assessed using data-limited approaches: Pagellus bogaraveo, Aphanopus carbo, Raja clavata, and Trachurus picturatus. No biological reference points are defined and stock and exploitation status relative to Maximum sustainable yield (MSY) are not assessed. The main issues identified were the lack of information regarding catches and population structure and validated analytical methods. Future studies should evaluate which methods for assessment may be suitable for each stock and identify what additional data are needed to improve the analyses. [ABSTRACT FROM AUTHOR]

Small pelagic fishes constitute a valuable food resource for human consumption and are also important components of marine food webs. At Madeira, a Portuguese archipelago in the eastern Atlantic, they are the target of a year-round purse-seine fishery operating mainly off the south coast of Madeira Island. Landings of this fishery are mostly composed of blue jack mackerel Trachurus picturatus, Atlantic chub mackerel Scomber colias, and small amounts of sardine Sardina pilchardus. A fisheries observation programme was carried out, from October 2016 to December 2017, to quantify discards and slipping. Large differences were detected in the proportion of each species present in the landings and in the gross catches. Large amounts of the caught S. pilchardus (76.6%), S. colias (42.6%) and even T. picturatus (14.2%) were either discarded dead or slipped. Reasons for discarding included small sizes and a low market value obtained in the first sale of these species. The fishing pattern in this region is in striking contrast with that for mainland Portugal, where S. pilchardus is the most valuable small pelagic species, fetching a high market price. The results of this study suggest a need for the introduction of specific measures to promote more effective utilisation of the resources. [ABSTRACT FROM AUTHOR]

Blue jack mackerel Trachurus picturatus collected at six sampling locations of the north‐east Atlantic Ocean (Azores, Madeira, Canaries, and Matosinhos, Peniche and Portimão, mainland Portugal) and one location in the Mediterranean (Sicily), were used to examine the genetic structure of this species. Three mitochondrial gene regions (cytochrome c oxidase subunit I, cytochrome b and control region) were used to study the genetic structure of the species in Macaronesia, as well as to compare the genetic diversity of this region with published results from its eastern distribution. All markers indicated the absence of genetic structure among populations, with high indices of genetic diversity. These results suggest that the species went through a bottleneck event, followed by a recent population expansion. Moreover, the comparison with previously published results from the T. picturatus Mediterranean distribution suggests the existence of a single panmictic population throughout the species' full range. This was, however, an unexpected result since other methodologies have shown the presence of, at least, three different population‐units in the NE Atlantic Ocean. [ABSTRACT FROM AUTHOR]

This work provides for the first time a description of the reproductive biology of Trachurus picturatus in Portuguese continental waters (between 41° 49′ and 36° 57′ latitude North). From January 2010 to December 2016 a total of 7409 individuals were sampled from bottom trawlers operating on the northwestern coast of Portugal. The observed sex ratio was 0.56 in favor of the females. Monthly variations in gonadosomatic index, proportion of actively spawning individuals, hepatosomatic index and Fulton′s condition factor were analyzed. More than 60% of spawning individuals were recorded in the first quarter, corresponding to the highest values of GSI, and Fulton's K and hepatosomatic index increased after the start of spawning. The morphometric relationships between total length and gutted weight showed significant correlations (high determination coefficient, r2 > 0.9) and isometric growth (b = 3) for both sexes. Results indicate that the spawning season of T. picturatus starts in December and extends until April–May, with a peak in March, which agrees with what has been indicated by other authors for the northeast Atlantic. This work provides important biological information on a species that although not subject to stock assessment is currently the 5th species landed by weight in Portuguese continental waters. [ABSTRACT FROM AUTHOR]

Highlights • Otolith shape analyses were used to infer the stock structure of Trachurus picturatus in the NE Atlantic. • Otolith shape analyses showed regional differences although with differences between the years. • The hereby data suggests that the blue jack mackerel population structure could be dynamic over time. Abstract The blue jack mackerel, Trachurus picturatus , is an economically important fishery resource of the NE Atlantic, commonly captured around the Macaronesian islands of Azores, Madeira and Canaries, but also along coastal Portugal mainland. Despite its importance for the fisheries industry, information regarding stock delineation for management and conservation purposes is still scarce. This study examines whether otolith shape is efficient to infer about the population structure of the species and if the obtained data is consistent over time. Individuals of T. picturatus were collected in 2013 and 2016 from six important fishery regions in the NE Atlantic: Azores, Madeira, Canaries and Portugal mainland – Matosinhos, Peniche and Portimão. Otolith shape indices and elliptic Fourier descriptors were investigated by uni and multivariate statistical analyses. Data showed regional differences in the otolith shape analysis, with differences between the years. Fish sampled in 2013 showed an overall low re-classification rate (43%) with a high overlap of individuals within sampling locations, suggesting a single population unit. However, samples from 2016 allowed the discrimination of three distinct spatial groups with a moderate overall correct re-classification (62%) - group 1 with samples from the Azores; group 2 with samples from the Canaries; and group 3 with samples from Madeira and Portugal mainland. The hereby data suggests that fish population structure could be dynamic over time, recommends a year-classes follow-up of the population units in the main fishing areas and stresses the need of holistic methodological approaches to study fish stocks. Furthermore the hereby observed complex spatial dynamic structure of the species demands region-specific requirement actions to ensure a rational management of the fishery. [ABSTRACT FROM AUTHOR]

Abstract: A total of 49,151 blue jack mackerel, Trachurus picturatus, (Bowdich) was collected in Madeira Island (North‐eastern Atlantic) between 2002 and 2016 to evaluate possible influence of fishing on landings and reproductive parameters. A decreasing trend in the length composition was observed over the study period and length at first maturity decreased by 2.78 cm TL. Maximum yield per recruit decreased from 2002 to 2016 but the corresponding fishing mortality was constant (Fmax = 0.4/year). Considering the fishing mortality level in 2016, it is evident that the stock may be exploited beyond its sustainability limit. Amendments of the purse‐seine fishing regulations and implementation of measures to reduce fishing effort are suggested. [ABSTRACT FROM AUTHOR]

The levels of 20 metals (aluminum, boron, barium, calcium, cadmium, cobalt, chromium, copper, iron, potassium, lithium, magnesium, manganese, molybdenum, sodium, nickel, lead, strontium, vanadium, and zinc) were analyzed in muscle and liver tissue of Trachurus picturatus marketed in the Canary Islands (Spain) by using inductively coupled plasma optical emission spectrometry. In the liver samples, the mean concentrations in milligrams per kilogram wet weight (wt) of Al (14.7), B (0.99), Ba (1.64), Ca (314), Cd (2.52), Co (0.15), Cu (4.07), Fe (106), Li (3.89), Mn (0.85), Mo (0.16), Na (1510), Ni (0.51), Pb (0.36), Sr (3.54), V (0.78), and Zn (23.13) were higher than those detected in the muscle samples in milligrams per killogram wet wt, which were as follows: Al (8.76), B (0.07), Ba (0.30), Ca (210), Cd (0.01), Co (0.01), Cu (1.51 ), Fe (7.33), Li (1.08), Mn (0.12), Mo (0.01), Na (697), Ni (0.11), Pb (0.04), Sr (1.45), V (0.01), and Zn (4.69). The mean concentrations of Cr, K, and Mg (0.14, 1,904, and 243 mg/kg wet wt, respectively) were higher in muscle than in liver (0.05, 1,333 and 236 mg/kg wet wt, respectively). The mean concentrations of Cd and Pb (0.01 and 0.04 mg/kg wet wt) in muscle did not exceed the maximum limits established by a European Commission regulation (0.1 mg of Cd/kg and 0.3 mg of Pb/kg, respectively). Considering a mean daily consumption of fish muscle for the adult population of 31.9 g/day published in the report on food consumption by the Spanish Ministry of Agriculture and Fisheries, Food and Environment, Mg made the highest contributions to the intake (2.58% for adult women of 60 kg and 2.22% for men of 70 kg), and the estimated intakes of Al (0.35 to 0.46 mg/day), Cd (0.55 to 0.74 mg/day) and Pb (1.66 to 5.53 mg/day) were below the respective established tolerable intakes. In conclusion, the results of this study show that the consumption of muscle from this benthopelagic species can be considered safe in terms of maximum legal limits, while consumption of liver is discouraged as a major source of exposure to toxic metals, such as Al, Cd, and Pb. [ABSTRACT FROM AUTHOR]

The blue jack mackerel, Trachurus picturatus , is an economically important fishery resource of the NE Atlantic, commonly captured around the Macaronesian islands of Azores, Madeira and Canaries, but also along coastal Portugal mainland. Despite this, information regarding the T. picturatus population structure is, at present, non-existent. One hundred and twenty individuals of T. picturatus were collected in 2013 from six important fishery regions of the NE Atlantic: Azores, Madeira, Canaries and Portugal mainland − Matosinhos, Peniche and Portimão. Elemental and isotopic signatures of whole sagittal otoliths were determined by inductively coupled plasma mass spectrometry and isotope ratio mass spectrometry, respectively. Elemental (Sr/Ca, Ba/Ca, Mg/Ca, Pb/Ca, Li/Ca, Fe/Ca and Mn/Ca) and isotopic ratios (δ 18 O and δ 13 C) were analysed with univariate and multivariate statistics to determine whether these chemical signatures provide insight into regional population structure. Whole otolith signatures gave distinct regional signatures, mainly driven by spatial differences in Sr/Ca, Ba/Ca, Li/Ca and δ 13 C, namely between the Portugal mainland and the oceanic islands. Furthermore, the results suggest for the first time that Portugal mainland, Azores, Madeira, and Canaries should be regarded as different population units. The high re-classification success rate (an overall of 81%) for these regions obtained from the quadratic discriminant function analysis supports these findings, and suggests the management of this fishery in the NE Atlantic as different stocks. [ABSTRACT FROM AUTHOR]

The use of parasites as biological tags for discriminating stocks of blue jack mackerel, Trachurus picturatus (Osteichthyes, Carangidae), in the northeast Atlantic Ocean is assessed herein. In this study the following parasites have been selected as possible biological tags: Anisakis spp. (Nematoda: Anisakidae), Rhadinorhynchus sp. (Acanthocephala: Rhadinorhynchidae), Nybelinia sp. (Cestoda: Tentaculariidae) and Bolbosoma sp. (Acanthocephala: Polymorphidae). Anisakis spp. was the most prevalent parasite taxon found in all localities, attaining higher values in fish from Peniche, mainland Portugal. The occurrence of Rhadinorhynchus sp. in fish from all studied areas was rare (prevalence <10%) but significantly different between localities, with higher values in both archipelagos. Nybelinia sp. specimens were only detected in fish from Madeira and cystacanths of the genus Bolbosoma were never detected. The distinctive pattern of infection of these parasite species points to the existence of three stocks of blue jack mackerel in the northeast Atlantic: one in Portuguese mainland waters, one in Madeira archipelago and another in the Canary archipelago. These results support the management strategy which treats the three populations studied as separate stocks. [ABSTRACT FROM AUTHOR]

This contribution intends to verify the type of fecundity regulation of the blue jack mackerel. For this purpose, the oocyte development process was analysed. A total of 158 ovaries were sampled between January 2009 and April 2010 from purse-seiners operating in the Madeira Island waters, NE Atlantic Ocean. Histological analysis and visual image analysis system were used to study the four main criteria applied for fecundity type determination: (1) presence of a hiatus between pre-vitellogenic and vitellogenic oocytes; (2) number of standing stock of advanced vitellogenic oocytes over the spawning season; (3) mean size of standing stock of advanced vitellogenic oocytes over the spawning season; and (4) the incidence of atresia over the spawning season. The analysis of the oocytes size frequency distribution showed that no distinct hiatus could be observed between pre-vitellogenic and vitellogenic oocytes during the spawning season. Considering the whole spawning period but the last month that was poorly sampled, the number of standing stock of advanced vitellogenic oocytes showed no decrease trend along the spawning season, the mean diameter of cortical alveoli oocytes and of the advanced stock of vitellogenic oocytes did not increase over the spawning season and the relative intensity of atresia was always high throughout this period. These findings suggest the blue jack mackerel displays an indeterminate fecundity. [ABSTRACT FROM AUTHOR]

In order to evaluate the use of parasites as biological tags to identify populations of the oceanic horse mackerel, Trachurus picturatus, two samples of 100 fish each, caught off the Madeira and Canary Islands from January to June 2009, were examined for the presence of anisakids, trypanorhynchs, acanthocephalans and liver coccidians. In T. picturatus from Madeira, prevalence of the coccidian Goussia cruciata reached 82%, whereas prevalence of the nematode Anisakis sp., the acanthocephalan Rhadinorhynchus cadenati and the trypanorhynch Nybelinia lingualis were 12.0%, 8.9% and 7.0%, respectively. In samples from the Canary Islands, prevalence of G. cruciata was 8.0%, Anisakis sp. and R. cadenati reached 5.0% and 42.0% respectively, and N. lingualis was not recovered. The absence of N. lingualis and the lower prevalence of Anisakis sp. appear to be related to the smaller size of the oceanic horse mackerels examined from the Canary Islands. Although significant differences in prevalence of two parasites, G. cruciata and R. cadenati, were found between the two regions investigated (χ2=125.13, df=1, p=0.000 and χ2=40.77, df=1, p=0.000), only G. cruciata was considered useful as a biological tag for the identification of populations of T. picturatus. In order to reach sound conclusions, an expansion of the temporal and spatial sampling strategy is recommended.

The blue jack mackerel Trachurus picturatus is a pelagic fish widely distributed in the NE Atlantic and also found in the Mediterranean and Black Seas. It is an economically important resource in the Macaronesian islands of Azores, Madeira and Canaries, but despite its fishery value and ecological importance, fluctuations in the landings are difficult to explain since studies regarding the population dynamics, stocks structure, fish movements and habitat connectivity are inexistent. The populations of marine pelagic fishes, in particular the migratory ones, such as T. picturatus,, may be erroneously considered an homogenous population unit because they show broad geographic distributions, large population sizes and high migratory movements. Stable isotope ratios, namely δ18O and δ13C, measured by standard mass spectrometric techniques in whole otolith samples of T. picturatus adults sampled in the fishery grounds of the Islands of Azores, Madeira and Canaries, and at the Portuguese mainland (Matosinhos, Peniche and Portimão) during the spring-summer of 2013 were analysed. The 18O signatures followed the general tendency taking into account the seawater temperatures of the sampling regions. 13C signatures showed however differences between the oceanic or continental origin of the fish. Both variables provided location-specific signatures. Further studies including mitochondrial and nuclear DNA studies are also been conducted to acquire new knowledge for fisheries conservation purposes.

The populations of marine pelagic fishes, in particular the migratory ones as the Trachurus picturatus (Bowdich 1825), may be erroneously considered an homogenous population unit because they show broad geographic distributions, large population sizes and high migratory movements. The blue jack mackerel, T. picturatus is widely distributed in the NE Atlantic and also found in the Mediterranean and Black Seas. It is an economically important resource in the Macaronesian islands of Azores, Madeira and Canaries, but despite its fishery value and ecological importance, fluctuations in the landings are difficult to explain since studies regarding the population dynamics, stocks structure, fish movements and habitat connectivity are inexistent. Moreover, genetic methods that can act as a complementary tool for stock identification and population dynamics have never been applied to this species. The blue jack mackerel was sampled by artisanal fleets in the Islands of Azores, Madeira and Canaries, and at the Portuguese mainland - Matosinhos, Peniche and Portimão -during the spring-summer of 2013. A tissue sample was taken from each individual and stored in 96% ethanol for molecular analysis. Total DNA was successfully extracted, followed by a Polymerase Chain Reaction amplification of part of the cytochrome b gene (Cyt b). Amplifications and sequencing of the Cyt b gene were carried out using published primers used for the Carangidae family (Cárdenas et al. 2005). Sequences from Greece and Turkey, available on GenBank, were added to our sequences and all analysed together. In total 46 sequences were analysed, including the closely related outgroup (Trachurus Trachurus). Preliminary results show that there are sequences in the GenBank that are incorrectly assigned to this species. In addition, within the samples collected one was proven to be T. Trachurus. Preliminary phylogeographic analyses revealed a very shallow phylogenetic tree and a star-like haplotype network, with haplotypes shared among populations. Further studies, including the number of sequences and the development of microsatellites are been conducted as part of a PhD program.

No information currently exists on the weight-length relationships of Sparidae: Axillary seabream Pagellus acarne (Risso, 1827), bogue Boops boops (Linnaeus, 1758); Mullidae: Red mullet Mullus barbatus (Linnaeus, 1758), surmulet Mullus surmuletus (Linnaeus, 1758) and Carangidae: Atlantic horse mackerel Trachurus trachurus (Linnaeus,1758), Mediterranean horse mackerel Trachurus mediterraneus (Steindachner 1863), Blue jack mackerel Trachurus picturatus (Bowdich 1825), seven commercial fish species of Oran Bay in Western Mediterranean Sea. Data are presented for the first time for that region of the Mediterranean Sea to contribute and help comparative growth studies. Samples were collected from commercial catches at Oran Bay fisheries in Algeria. The values of the slope b in the lengthweight relationship, W=aLb ranged from 2.841 to 3.296. The coefficients of correlation r² were comprised between 0.85 and 0.97. “a” and “b” parameters were compared with other fishing sites for the same fish species with Froese plot [Log a=ƒ(b)]. [ABSTRACT FROM AUTHOR]

Blue jack mackerel, Trachurus picturatus, is a carangid fish which constitutes an important commercial resource in the north-east Atlantic. Its metazoan parasite community from Portuguese mainland waters was investigated here for the first time. Nine parasite taxa were found, most of which are common parasites of Trachurus spp. The parasite community was broadly similar to that of the Atlantic horse mackerel, T. trachurus, from the same region, but two digenean species were detected in blue jack mackerel, Monascus filiformis and Tergestia sp., which did not occur in horse mackerel from this region. A comparison with the two previous studies of T. picturatus parasite communities shows that continental-shelf regions are characterized by higher prevalences of digenean trematodes and an absence of trypanorhynch cestodes, in contrast with oceanic regions. [ABSTRACT FROM AUTHOR]

The observation of a new species in a new area represents the first opportunity to follow and study the dynamics of colonization and understand how a new species arrives, what are its movements and its potential impact. The discovery of a large number of species outside their usual area of distribution is probably the most important reason for the increase in perceived biodiversity of the Adriatic ichthyofauna. A total of 4 specimens of T. picturatus were caught in the period MayJune 2011 in the surroundings of an offshore gas platform in the Northern Adriatic Sea. Scientific literature depicts this species as rare in the Adriatic Sea, indicating and suggesting the Pomo Pit (Central Adriatic Sea) as the Northern latitudinal limit of its distribution. On this basis, this paper reports the first record of T. picturatus in the Northern Adriatic basin, suggesting an expansion of its spatial distribution. [ABSTRACT FROM AUTHOR]

The reproductive cycle of the blue jack mackerel, Trachurus picturatus, had not been described for the Canary Islands. Between March 2005 and March 2006 monthly samples of T. picturatus were collected randomly at the central fishery wharf from the commercial catches of purse-seiners in Tenerife Island waters ( Canary Islands). Some 2472 specimens were analysed, with total lengths from 10.4 to 31.9 cm. Although females outnumbered males in summer, males were more abundant in the sex ratio (1.36 : 1). Based on the monthly evolution of the gonado-somatic index and the proportion of mature individuals, the spawning season occurred between January and April, peaking in February. Lengths at first maturity ( LFM) were calculated from the maturity ogives by the Gompertz model for all specimens (22.79 cm), for males (21.20 cm) and for females (23.05 cm). In this area the minimum legal size for T. picturatus is actually smaller than the length at first maturity and should be revised to avoid depletion of the stock. [ABSTRACT FROM AUTHOR]

Abstract: Fish egg identification is relevant for a variety of ecological studies including the application of egg production methodologies to estimate population abundance. The Daily Egg Production Method (DEPM) has been applied triennially, since 2007, for horse mackerel (Trachurus trachurus) in Iberian waters. In this region a less abundant species of the same genus co-occurs, blue jack mackerel (T. picturatus), but up to now little is known on its spawning seasonality. At present, horse mackerel egg identification in plankton samples is done based on morphological characteristics. Eventual egg misidentification may lead to inaccurate estimates of stock biomass. During the 2010 DEPM survey, spawning blue jack mackerel were caught together with horse mackerel in the same fishing haul. Artificial fertilization was undertaken for both species and egg development followed. Embryogenesis was divided into eleven stages and the morphological features were compared for the two species. The rates of development were assessed using a multinomial modelling approach. The experiments showed that eggs of T. picturatus are very similar in appearance to those of T. trachurus but the former are slightly but significantly larger (chorion and oil globule diameters). Considerable overlap exists among the egg characteristics of the two species indicating that morphological separation of eggs of these species are problematic. Egg development for T. trachurus was faster than for T. picturatus. Entire egg development until hatching occurred in 67h for T. trachurus while T. picturatus needed an extra 8h at a water temperate of 16.5°C. [Copyright &y& Elsevier]

The article presents a study which aims to evaluate the foraging behavior of six different populations of Cory's shearwaters (Calonectris diomedea) including Trachurus picturatus, Sardina pilchardus and Exocoetus volitans. The study used three techniques to examine the foraging and trophic ecology of shearwaters in the North Atlantic region such as deployment of data loggers, collection of diet and blood samples from a representative of each population and measurement of stable isotopes of the major prey species in every population. Results show that Tracharus picturatus was the principal prey for populations around oceanic environments such as Azores and Desertas. Moreover, cephalopods or squids were discovered to be an important diet for the entire population.

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. [ABSTRACT FROM AUTHOR]

Abstract: Sensory, physicochemical and microbiological analyses were carried out on Mediterranean horse mackerel and blue jack mackerel in order to determine quality changes during storage in ice. Sensory results indicated that whole Mediterranean horse mackerel and blue jack mackerel used in this trial had a shelf-life of 10 and 7days, respectively. Fishtester and Fishchecker measurements showed that the quality of blue jack mackerel had deteriorated more rapidly. Fishtester values of the blue jack mackerel and the Mediterranean horse mackerel were reduced from 59±10.1 to 14.8±2.8 and from 85.3±13.2 to 25.6±7.8, respectively during the storage time. Fishchecker gave red sign (unfit for consumption) for first time on day 7 and day 6 in Mediterranean horse mackerel and blue jack mackerel, respectively. The pH of Mediterranean horse mackerel muscle was consistently lower than the pH of blue jack mackerel muscle during the storage period. The pH values of both species muscle increased gradually with time and pH value equal to 7 had almost coincided with the end of shelf-life. Bacterial loads in both fish species muscle remained rather low prior to day 10 (<6log10 cfu/g). The longer shelf-life of Mediterranean horse mackerel as determined by sensory evaluation was not reflected in microbiological results suggesting that the difference was due to lower rate of autolysis rather than to reduced microbial activity. [Copyright &y& Elsevier]

The article identifies one-hundred and fifteen anisakid larvae from three different fish hosts, Aphanopus carbo, Scomber japonicus, and Trachurus picturatus, which were caught in Madeiran waters. It uses the polymerase chain reaction linked to restriction fragment length polymorphism to identify the anisakid larvae. The article suggests that the taxon are more similar to A. ziphidarum than to other species of the genus.

We assessed the effects of different quality fish species and reductions in their abundance in the growth of Roseate Tern (Sterna dougallii) chicks in the Azores. An energetic balance model was developed, which accounts for the energy available from ingested fishes and the energy expenditure by the chicks. Fish species ingested by Roseate Tern chicks were mainly Trachurus picturatus, Scomberesox saurus, Macroramphosus scolopax and Capros aper. Energy expenditure was defined by the basal metabolic rate (BMR), which depends on chick’s weight, plus a multiple of BMR, obtained by calibration and accounting for unspecified energetic losses. Real data obtained in June–July of 1996 and 1995 were used to calibrate and validate the model, respectively. Regressions between observed and predicted data showed a higher fitting level for 1996 than for 1995, which seems to be related with the need for more accurate estimations of assimilation efficiency and energy expenditure parameters. Of the four main prey species, T. picturatus was the most energetically favourable because of its high length–weight regression and to the capacity of chicks to swallow T. picturatus with an average length of 8.71 cm. C. aper had a higher length–weight relationship, but chicks were only able to ingest items <5 cm because this species is wider than T. picturatus. S. saurus and M. scolopax were energetically less efficient because they had a lower length–weight relationship. Observations suggest that the availability of less energetic fish (e.g. M. scolopax) leads to higher delivery rates by the parents and, consequently, to higher ingestion rates by the chicks. However, both observations and predictions suggest that the growth efficiency is lower than when the chicks were fed with T. picturatus with an average length of 8.71 cm. Additionally, the model predicts that chicks with 23 days of age will attain 85 and 56 g, according to a 25% reduction in prey within a year of energetically more and less favourable prey, respectively. Chicks in the first situation are still likely to fledge, while in the second case, chick survival is certainly compromised. In summary, the growth of Roseate Tern chicks in the Azores will be significantly reduced in response to a decrease in energy intake resulting from provisioning of low quality fish species and chick survival is compromised whenever this factor is associated with a significant (25%) reduction in fish stocks. This model proved to be a highly dynamic tool in assessing variations in postnatal growth of Roseate Terns in response to variations in food quality and quantity and it should be of interest in the conservation strategy of this species. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

Growth modelling is essential to inform fisheries management but is often hampered by sampling biases and imperfect data. Additional methods such as interpolating data through back-calculation may be used to account for sampling bias but are often complex and time-consuming. Here, we present an approach to improve plausibility in growth estimates when small individuals are under-sampled, based on Bayesian fitting growth models using Markov Chain Monte Carlo (MCMC) with informative priors on growth parameters. Focusing on the blue jack mackerel, Trachurus picturatus, which is an important commercial fish in the southern northeast Atlantic, this Bayesian approach was evaluated in relation to standard growth model fitting methods, using both direct readings and back-calculation data. Matched growth parameter estimates were obtained with the von Bertalanffy growth function applied to back-calculated length at age and the Bayesian fitting, using MCMC to direct age readings, with both outperforming all other methods assessed. These results indicate that Bayesian inference may be a powerful addition in growth modelling using imperfect data and should be considered further in age and growth studies, provided relevant biological information can be gathered and included in the analyses. [ABSTRACT FROM AUTHOR]