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The origin and life history of 186 Atlantic salmon caught at sea within Icelandic waters were investigated using microsatellites to assess the origin and scales and otoliths to assess freshwater and sea age. A total of 184 samples were aged using scales or otolithes or both. Most of the samples were from individuals in their first year at sea (72.8%). The freshwater age varied from 1 to 5 years with an average of 2.6 years. The most common freshwater age was 2 years (42%), with a further substantial proportion of 3-year-old fish (28%). Genetic assignment of individual fish to their most likely population of origin was performed using Bayesian genetic individual assignments with a baseline consisting of 284 Eastern Atlantic rivers and 466 sample sites genotyped at the 14 microsatellite. A total of 186 samples of salmon caught at sea were assigned to their origin. Eight samples, from post-smolts and caught close to land, were assigned as having come from Iceland. Of the remaining 178 samples, 121 individuals (68%) were from the Southern Group, i.e. from mainland Europe, the UK, and Ireland, 53 individuals (30%) were from the Northern Group, i.e. Scandinavia and Northern Russia, and 4 individuals were from Iceland (2%). Stock mixture proportions were estimated for four periods using ONCOR and cBAYES. Stock mixture analysis generally supported the individual assignments, but did not suggest a seasonal component to the distribution of salmon stocks. These results indicate that the sea south and east of Iceland are important as feeding areas for migrating Atlantic salmon, particularly for salmon originating in the UK, Ireland, and southern Europe. Furthermore, the lack of adult Icelandic fish so close to Iceland is remarkable and suggests that Atlantic salmon from Icelandic stocks are using different feeding grounds. [ABSTRACT FROM AUTHOR]

Lumpfish, or lumpsucker, Cyclopterus lumpus (Linnaeus, 1758) is widely distributed in the North Atlantic Ocean. It has a considerable economic value and substantial fisheries occur in several North Atlantic regions owing to the use of its fully ripe internal egg masses in the ovaries as an alternative to sturgeon caviar. Despite being intensively fished in several locations, biological knowledge is limited and no genetic structure information is available. In this study, the stock structure of C. lumpus was investigated across the North Atlantic using ten microsatellite loci. Out of ten loci, two exhibited higher level of differentiation but their inclusion/exclusion from the analyses did not drastically change the observed genetic pattern. A total of three distinct genetic groups were detected: Maine–Canada–Greenland, Iceland–Norway and Baltic Sea. These results, discussed in terms of origin of differentiation, gene flow, and selection, showed that gene flow was rather limited among the detected groups, and also between Greenland and Maine–Canada. [ABSTRACT FROM AUTHOR]

Due to an improved understanding of past climatological conditions, it has now become possible to study the potential concordance between former climatological models and present-day genetic structure. Genetic variability was assessed in 26 samples from different rivers of Atlantic salmon in Iceland (total of 2,352 individuals), using 15 microsatellite loci. F-statistics revealed significant differences between the majority of the populations that were sampled. Bayesian cluster analyses using both prior information and no prior information on sampling location revealed the presence of two distinguishable genetic pools - namely, the Northern (Group 1) and Southern (Group 2) regions of Iceland. Furthermore, the random permutation of different allele sizes among allelic states revealed a significant mutational component to the genetic differentiation at four microsatellite loci (SsaD144, Ssa171, SSsp2201 and SsaF3), and supported the proposition of a historical origin behind the observed variation. The estimated time of divergence, using two different ABC methods, suggested that the observed genetic pattern originated from between the Last Glacial Maximum to the Younger Dryas, which serves as additional evidence of the relative immaturity of Icelandic fish populations, on account of the re-colonisation of this young environment following the Last Glacial Maximum. Additional analyses suggested the presence of several genetic entities which were likely to originate from the original groups detected. [ABSTRACT FROM AUTHOR]

The intense fishing mortality imposed on Atlantic cod in Icelandic waters during recent decades has resulted in marked changes in stock abundance, as well as in age and size composition. Using a molecular marker known to be under selection ( Pan I) along with a suite of six neutral microsatellite loci, we analysed an archived data set and revealed evidence of distinct temporal changes in the frequencies of genotypes at the Pan I locus among spawning Icelandic cod, collected between 1948 and 2002, a period characterized by high fishing pressure. Concurrently, temporal stability in the composition of the microsatellite loci was established within the same data set. The frequency of the Pan IBB genotype decreased over a period of six decades, concomitant with considerable spatial and technical changes in fishing effort that resulted in the disappearance of older individuals from the fishable stock. Consequently, these changes have likely led to a change in the genotype frequencies at this locus in the spawning stock of Icelandic cod. The study highlights the value of molecular genetic approaches that combine functional and neutral markers examined in the same set of individuals for investigations of the selective effects of harvesting and reiterates the need for an evolutionary dimension to fisheries management. [ABSTRACT FROM AUTHOR]

Pampoulie, C., Skirnisdottir, S., Hauksdottir, S., Olafsson, K., Eiríksson, H., Chosson, V., Hreggvidsson, G. O., Gunnarsson, G. H., and Hjorleifsdottir, S. 2011. A pilot genetic study reveals the absence of spatial genetic structure in Norway lobster (Nephrops norvegicus) on fishing grounds in Icelandic waters. – ICES Journal of Marine Science, 68: 20–25. Stock structure of Norway lobster off southern Iceland was investigated using 12 microsatellite loci. No genetic method detected significant genetic differentiation among the locations sampled, even among Icelandic samples and an out-group from Scotland. Testing the power of resolution of microsatellite loci, the loci and sample sizes used were sufficient to detect significant genetic differentiation with confidence. The lack of genetic structure is discussed in terms of the level of gene flow, recent isolation of populations, and the statistical power of the experimental design. [ABSTRACT FROM PUBLISHER]

We report the development of new PCR assays and loading panels for the Atlantic salmon using 15 microsatellite loci. A total of 8, 3 and 4 loci were coamplified in three separate PCRs using labelled primers and loaded on the ABI DNA analyzer in two separate panels. Amplified alleles were clearly typed, and easily interpretable results were obtained. The method was successfully applied in different laboratories, even when different types of DNA polymerase were employed. The method is useful for analysing paternity, population genetics and conservation as well as for selective breeding programmes. [ABSTRACT FROM AUTHOR]

Pampoulie, C., Gíslason, D., and Daníelsdóttir, A. K. 2009. A “seascape genetic” snapshot of Sebastes marinus calls for further investigation across the North Atlantic. – ICES Journal of Marine Science, 66: 2219–2222.A collection of 376 golden redfish (Sebastes marinus) from several fishing grounds in the North Atlantic in late 2001 was genotyped at nine microsatellite loci to provide preliminary information on the possible genetic structure in this species. Landscape genetic analysis revealed the presence of two distinct genetic pools within the North Atlantic, suggesting that S. marinus might be structured within the North Atlantic and should be the subject of more investigation. [ABSTRACT FROM PUBLISHER]

Stefánsson, M. Ö., Reinert, J., Sigurðsson, Þ., Kristinsson, K., Nedreaas, K., and Pampoulie, C. 2009. Depth as a potential driver of genetic structure of Sebastes mentella across the North Atlantic Ocean. – ICES Journal of Marine Science, 66: 680–690. A primary question that remains to be answered about the fishery for Sebastes mentella is whether it exploits several stocks within the North Atlantic Ocean. To address this issue, 1240 redfish were collected from several fishing grounds in late 2006 and early 2007 and genotyped at 12 microsatellite loci. Contemporary allele frequencies were compared with archived data to examine the temporal stability of the genetic structure. The analyses all revealed the presence of three genetically distinguishable clusters, which persisted throughout the study period, suggesting that the genetic structure detected is genuine. Cluster D included fish from the deep Irminger Sea and west Faroe Islands, and Cluster I included fish only from the Icelandic shelf. All other fish grouped in a third cluster (S). Further analyses revealed that the genetic pattern observed was not primarily attributable to isolation by distance, but rather to depth distribution. [ABSTRACT FROM PUBLISHER]

Most studies of the genetic structure of Atlantic cod have focused on small geographical scales. In the present study, the genetic structure of cod sampled on spawning grounds in the North Atlantic was examined using eight microsatellite loci and the Pan I locus. A total of 954 cod was collected from nine different regions: the Baltic Sea, the North Sea, the Celtic Sea, the Irish Sea and Icelandic waters during spring 2002 and spring 2003, from Norwegian waters and the Faroe Islands (North and West spawning grounds) in spring 2003, and from Canadian waters in 1998. Temporal stability among spawning grounds was observed in Icelandic waters and the Celtic Sea, and no significant difference was observed between the samples from the Baltic Sea and between the samples from Faroese waters. F-statistics showed significant differences between most populations and a pattern of isolation-by-distance was described with microsatellite loci. The Pan I locus revealed the presence of two genetically distinguishable basins, the North-west Atlantic composed of the Icelandic and Canadian samples and the North-east Atlantic composed of all other samples. Permutation of allele sizes at each microsatellite locus among allelic states supported a mutational component to the genetic differentiation, indicating a historical origin of the observed variation. Estimation of the time of divergence was approximately 3000 generations, which places the origin of current genetic pattern of cod in the North Atlantic in the late Weichselian (Wisconsinian period), at last glacial maximum. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94, 315–329. [ABSTRACT FROM AUTHOR]

Pampoulie, C., Steingrund, P., Stefánsson, M. Ö., and Daníelsdóttir, A. K. 2008. Genetic divergence among East Icelandic and Faroese populations of Atlantic cod provides evidence for historical imprints at neutral and non-neutral markers. – ICES Journal of marine Science, 65: 65–71.During the past decade, genetic markers have been used increasingly to improve stock discrimination and to aid fisheries management. Today, the Icelandic and Faroese Plateau cod (Gadus morhua) are managed as separate units, belonging to ICES Subareas Va and Vb1, respectively. There is little information on the genetic connectivity of the two units, however, except in terms of tagging experiments which revealed limited adult migration between the two areas, and few genetic studies describing genetic differentiation among Faroese and East Icelandic cod. Here, previously published data on the genetic structure of Icelandic cod were combined with new data from the Faroe Plateau to assess the level and the source of genetic variability of Atlantic cod around the Iceland–Faroe Ridge and the potential sources of genetic variation. In all, 771 cod were genotyped at nine microsatellite loci and at the Pantophysin locus (Pan I). The genetic markers employed were congruent and showed that South Icelandic and East Icelandic–Faroese Plateau populations have limited genetic connectivity. Diversifying selection associated with restricted gene flow is likely to explain the observed pattern with the Pan I locus. Further analyses detected historical imprints in the microsatellite data, suggesting that the divergence could be due to isolation of different cod populations during the last glacial maximum. [ABSTRACT FROM PUBLISHER]

Allelic variation at nine microsatellite loci and the Pan I locus provides evidence that Atlantic cod (Gadus morhua) around Iceland is genetically structured (FST = 0. 003 and FST = 0. 261, respectively). A total of 2534 cod were sampled at 22 spawning locations. For both types of markers, most of the significant pairwise FST resulted from northeastern–southwestern comparisons. A multidimensional scaling analysis based on FST, a spatial hierarchical analysis of molecular variance (SAMOVA) and a hierarchical analysis of molecular variance (AMOVA), conducted on both types of markers confirmed a genetic differentiation between cod from the northeastern and southwestern regions. Genetic discontinuities were revealed across two main current fronts in the southeast and northwest, where the cold and warm water masses meet. The AMOVA also detected genetic differences with depth. Expected and observed heterozygosity of microsatellite loci significantly decreased with depth, whereas the B allele frequency at the Pan I locus increased. A tagging experiment of spawning fish conducted during the same years as the genetic work revealed that tagged individuals released in the southwestern region seldom migrated to the northeastern region and vice versa, suggesting that the southwestern and northeastern populations of Atlantic cod around Iceland represent two distinct spawning components. [ABSTRACT FROM AUTHOR]

Eighteen new microsatellite loci consisting of 10 di-, 5 tri-, 2 tetra- and 1 heptanucleotide repeats are introduced for the Atlantic cod ( Gadus morhua L.). All loci were co-amplified in two polymerase chain reactions (plus two previously published microsatellites) and all products were typed clearly. The number of alleles per locus ranged from six (PGmo130) to 45 (PGmo76) and the observed heterozygosity ranged from 0.356 (PGmo130) to 0.957 (PGmo95). All loci except one followed Hardy–Weinberg expectations. Genetic linkage disequilibrium analysis between all pairs of loci did not yield any significant values. [ABSTRACT FROM AUTHOR]

Nine out of 22 microsatellite primers tested were successfully amplified on three samples of cod Gadus morhua L. (two contemporary and one archived otolith samples). All loci were polymorphic (5–23 alleles/locus). The average observed heterozygosity across loci and samples was 0.625, ranging from 0.294 to 0.895 at each locus. All loci were under Hardy–Weinberg equilibrium, except PGmo56 that showed significant excess of heterozygotes in all studied samples. The isolated loci were suitable for degraded DNA and therefore useful for conducting a long-term temporal study with DNA obtained from archived otoliths of cod. [ABSTRACT FROM AUTHOR]