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Peroderma cylindricum Heller, 1865 is a parasitic copepod that infects the pilchard Sardina pichardus (Walbaum, 1792), causing a serious disease. Despite its substantial impact on the fish, little is known regarding the trophic relationship between the parasite and its host. We studied this aspect of the host-parasite interaction through a comparative study of the fatty acid composition of the parasite and its host. Gas chromatography showed that, overall, the fatty acid pattern of the parasitic copepod reflects that of its host with a predominance of palmitic acid, stearic acid, oleic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Total lipids of the host were characterized by higher percentages of saturated fatty acids and polyunsaturated n-6 fatty acids whereas P. cylindricum showed a significantly higher proportion of polyunsaturated n-3 fatty acids, mainly DHA and EPA. Our findings revealed the ability of the parasite to selectively hijack some fatty acids from the host, especially DHA, and most likely biosynthesize de novo some other fatty acids such as EPA. The scarcity of arachidonic acid in the host versus its abundance in the parasite may reflect the hijacking of this fatty acid from the infected fish to be used in gonad maturation. ARA might also be used by the parasite to contribute in the overcoming of the host defenses through suppressive molecules derived from this fatty acid. [ABSTRACT FROM AUTHOR]

Bernal, M., Stratoudakis, Y., Wood, S., Ibaibarriaga, L., Uriarte, A., Valdés, L., and Borchers, D. 2011. A revision of daily egg production estimation methods, with application to Atlanto-Iberian sardine. 2. Spatially and environmentally explicit estimates of egg production. – ICES Journal of Marine Science, 68: .A spatially and environmentally explicit egg production model is developed to accommodate a number of assumptions about the relationship between egg production and mortality and associated environmental variables. The general model was tested under different assumptions for Atlanto-Iberian sardine. It provides a flexible estimator of egg production, in which a range of assumptions and hypotheses can be tested in a structured manner within a well-defined statistical framework. Application of the model to Atlanto-Iberian sardine increased the precision of the egg production time-series, and allowed improvements to be made in understanding the spatio-temporal variability in egg production, as well as implications for ecology and stock assessment. [ABSTRACT FROM PUBLISHER]

Solari, A. P., Santamaría, M. T. G., Borges, M. F., Santos, A. M. P., Mendes, H., Balguerías, E., Díaz Cordero, J. A., Castro, J. J., and Bas, C. 2010. On the dynamics of Sardina pilchardus: orbits of stability and environmental forcing. – ICES Journal of Marine Science, 67: 1565–1573.The dynamics of Sardina pilchardus in Iberian upwelling are examined. Spawning-stock biomass (SSB), recruitment (R), and production (R/SSB) data for the years 1978–2006 are analysed in relation to the upwelling index (UPW) and sea surface temperature (SST). The population oscillates in two relatively stable orbits (identified by multiresolution decomposition of the recruitment series) because the external forcing (UPW and SST) are the inverse of each other and the synchrony is lost between the two external variables, R and R/SSB as they shift towards steep, negative (depensatory) trends. Such mechanics may have induced recruitment failures and significant decreases in abundance of Iberian sardine. The relationships are assumed to validate a complex and dynamic continuum (multiple orbits of stability) and an alternative variable-carrying-capacity population model. Radial systems with two orbits of stability are proposed for the R/SSB and S/SSB (where S is the stock size) relationships. Results are discussed in relation to classical and alternative SR models to address stock rehabilitation and fishing mortality issues as the population shifts towards low recruitment and abundance, and critical factors to consider in developing exploitation strategies for systems with multiple orbits of stability are discussed. [ABSTRACT FROM PUBLISHER]

Morote, E., Olivar, M. P., Villate, F., and Uriarte, I. 2010. A comparison of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) larvae feeding in the Northwest Mediterranean: influence of prey availability and ontogeny. – ICES Journal of Marine Science, 67: 897–908.The feeding ecology of the larvae of the two most important small pelagic species in the western Mediterranean, anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus), is investigated. Samples were collected in early summer (anchovy) and autumn (sardine). Composition of the diet and prey selectivity were compared over the course of ontogeny in anchovy (2.7–14.5 mm standard length, SL) and sardine (5.5–15.8 mm SL) larvae. Anchovy larvae begin feeding on prey items >150 µm at smaller sizes than sardine larvae, and the diets of both species are based mainly on copepod nauplii and postnauplii. Seasonal differences in the composition of the plankton influenced the contributions of prey types to the diets of the two species, e.g. the cladoceran Evadne spp. in anchovy and the tintinnid Codonellopsis sp. in sardine. Although copepod eggs are generally present in the diets of larval clupeoids, they were not major components of the diets of the species considered here. Despite morphological similarity, selection patterns were different between the species and changed through ontogeny. [ABSTRACT FROM PUBLISHER]

Results from sampling for sardine (Sardina pilchardus) eggs at station L4 in the coastal Western English Channel over the period 1988–2008 are presented and discussed in relation to environmental conditions. As previously observed in this area, there is a summer spawning season (mid-March to early July) and one in the autumn (early September to mid-November). The historical trend for increasing autumn spawning has continued. The mean spawning temperatures were 12.6 and 14.5°C for the summer and autumn seasons, respectively. Temperature was negatively correlated with summer egg abundance and positively with autumn egg abundance. A negative correlation between egg abundance and the North Atlantic Oscillation index suggested a link between egg numbers and plankton production. [ABSTRACT FROM PUBLISHER]

Chlaida, M., Laurent, V., Kifani, S., Benazzou, T., Jaziri, H., and Planes, S. 2009. Evidence of a genetic cline for Sardina pilchardus along the Northwest African coast. – ICES Journal of Marine Science, 66: 264–271.In all, 700 Sardina pilchardus from 14 locations throughout the Atlantic and Mediterranean Moroccan coastlines were screened for eight enzymatic loci that show polymorphism. Analysis of allelic frequencies showed a genetic break in the area of the Bay of Agadir, segregating two groups of samples, confirmed by analysis of molecular variance; a first consisting of Sidi Ifni (29°12′N) and southern samples down to the southern limit of the species in Mauritania (19°03′N 16°28′W), and a second starting in the Bay of Agadir (30°48′N) and consisting of northern samples that appeared homogeneous with the Mediterranean samples. Specifically, a survey of the SOD* loci demonstrated a genetic cline in allelic frequencies along the coastline. Using a clinal variation model under a state of equilibrium, we estimate a dispersal rate of 189 ± 52 km per generation between Mauritania and Ras Kebdana. This major break towards the south of the Bay of Agadir offers a new perspective on the management of sardine, which ideally ought now to be managed as two stocks along the Moroccan coast. The break is most likely induced by hydrodynamic influences that virtually isolate southern from northern populations. [ABSTRACT FROM PUBLISHER]

Analyzes the genetic structure of the Sardina pilchardus population in the Bay of Biscay. Analysis of allozymes; Relationship between geographic factors and genetic indices; Factor to consider when investigating the potential for selective pressure of sardine.

The aim of this work was to study the influence of bacterial epiflora on egg hatching of the sardine (Sardina pilchardus) obtained from a natural environment (Ría de Vigo, Spain) during the spawning season of the sardine (from January to June). Total bacteria, viable bacteria or the presence of specific potential pathogens for eggs, such as Pseudoalteromonas piscicida and Tenacibaculum (Flexibacter) ovolyticus, did not affect the viability of sardine eggs. Additionally, no relationship was observed between the presence of Vibrio spp., pathogenic for fish larvae, and the egg hatching. This was probably because the amount of bacteria associated with the eggs were between 102 and 104 orders lower than those found so far on the eggs of different fish species in rearing systems. Therefore, epiphytic bacteria did not affect the wild sardine eggs and, hence, in the area studied, it is probably not an important factor affecting annual recruitment success of this pelagic fish species. [Copyright &y& Elsevier]

Pelagic fishes generally disperse at dusk and aggregate in schools at dawn. The dynamics (duration, variation in school number, and characteristics) of these two behavioural processes have been studied during a 26 h survey in a small area of high fish abundance in the Catalan Sea (Spain). The dynamics of aggregation and dispersion were investigated using a dual-beam vertical echo-sounder (BioSonics) connected to a special school integrator software package (INES-MOVIES-B) which estimates school parameters in terms of size, geometry, and density. This study shows that, during the night, fish dispersion is limited and schools can still be observed. They are characterized by a highly skewed distribution of the cross-sectional area (many small schools plus a few medium and large schools), low values of packing density and biomass, and irregular shape, while during the day there are only a few schools which have a lower variability of the area, high values of packing density, and a more regular shape. The dynamics of schooling are different between dawn (fast aggregation) and dusk (slower dispersion). [ABSTRACT FROM PUBLISHER]

Systematic acoustic surveys to estimate the Spanish fraction of the Atlantic sardine stock were begun in 1983. Since 1991, with the use of the new SIMRAD EK500 echo-sounder–echo-integrator, the area covered has been extended to the 1000 m depth contour to observe the complete distribution of the main pelagic species. The last three surveys, from spring 1991 to spring 1993, had a range of 20–1000 m depth. They were first analysed using traditional methodology, which does not give any estimation of the variance. The data were therefore analysed using geostatistical techniques and the resulting estimates of relative abundance were compared. Sardine showed high variability between years and zones both in distribution and density, expressed as number of fish per square nautical mile. The two methods of analysis gave different biomass estimates by zone, especially in 1993. Variograms computed over areas of fish presence did not show, in general, a clear spatial structure and sills were reached at 3 nmi of range. The precision of these variograms was low, ranging from 23–40%, expressed as relative standard error. In order to improve precision it is necessary to increase sampling intensity and change the survey grid. For sardine, a systematic parallel survey design with a random start and 6 nmi between transects would be more appropriate. [ABSTRACT FROM PUBLISHER]

Background The European sardine (Sardina pilchardus Walbaum, 1792) is culturally and economically important throughout its distribution. Monitoring studies of sardine populations report an alarming decrease in stocks due to overfishing and environmental change, which has resulted in historically low captures along the Iberian Atlantic coast. Important biological and ecological features such as population diversity, structure, and migratory patterns can be addressed with the development and use of genomics resources. Findings The genome of a single female individual was sequenced using Illumina HiSeq X Ten 10x Genomics linked reads, generating 113.8 gigabase pairs of data. Three draft genomes were assembled: 2 haploid genomes with a total size of 935 megabase pairs (N50 103 kilobase pairs) each, and a consensus genome of total size 950 megabase pairs (N50 97 kilobase pairs). The genome completeness assessment captured 84% of Actinopterygii Benchmarking Universal Single-Copy Orthologs. To obtain a more complete analysis, the transcriptomes of 11 tissues were sequenced to aid the functional annotation of the genome, resulting in 40,777 genes predicted. Variant calling on nearly half of the haplotype genome resulted in the identification of >2.3 million phased single-nucleotide polymorphisms with heterozygous loci. Conclusions A draft genome was obtained, despite a high level of sequence repeats and heterozygosity, which are expected genome characteristics of a wild sardine. The reference sardine genome and respective variant data will be a cornerstone resource of ongoing population genomics studies to be integrated into future sardine stock assessment modelling to better manage this valuable resource. [ABSTRACT FROM AUTHOR]