Tag: Composition

Peer-reviewed articles

Discriminating populations of Atlantic herring mixing in the Norwegian Sea feeding ground using single nucleotide polymorphisms (SNPs)

Atlantic herring Clupea harengus feeding in the Norwegian Sea are assumed to consist of Norwegian spring spawners (NSSH), Icelandic summer spawners (ISSH) and North Sea autumn spawners (NSAH). Putative Norwegian autumn spawners (NASH), Faroese autumn (FASH) and spring (FSSH) spawners also feed in the area.

However, until there is a method to discriminate between populations in mixed samples, fishery and survey data from the Norwegian Sea will be solely attributed to the predominating NSSH, ultimately causing biased stock assessments.

Hence, we evaluated if a panel of 120 single nucleotide polymorphisms (SNPs) associated with spawning characteristics and salinity preferences would be an effective discrimination tool. The overall observed levels of genetic differentiation were high (FST = 0.57, p < 0.001, 95% CI: 0.51−0.62). Spawners from stocks under current management (NSSH, NSAH and ISSH) were well separated, but the putative populations were not. Discriminant analysis of principal component as well as Structure runs confirmed the differentiation observed with FST. When the SNP panels were tested on commercial fishery samples of NSSH east of Iceland, up to 16% were assigned to ISSH.

This implies that catch data are seriously biased and demonstrates the potential of SNP panels as a tool to solve the problem. However, work is needed to develop improved SNP panels that effectively separate the putative populations from the managed stocks. We recommend that such a tool should be established in regular sampling of fisheries and surveys in the Norwegian Sea and accounted for in future stock assessments, advice and management.

Reports

Seasonal and geographical variation in chemical composition and lipid stability of Atlantic mackerel (Scomber scombrus) caught in Icelandic waters

Published:

01/12/2015

Authors:

Paulina E. Romotowska, Magnea G. Karlsdóttir, María Guðjónsdóttir, Sigurjón Arason, Hörður G. Kristinsson

Supported by:

AVS Fisheries Research Fund (R 040-12)

Contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Seasonal and geographical variation in chemical composition and lipid stability of Atlantic mackerel (Scomber scombrus) caught in Icelandic waters

During the time that mackerel is off the coast of Iceland, it is eaten a lot, which causes it to gain weight quickly, with the result that the meat becomes very sensitive to handling. In this study, mackerel caught in the summer seasons of 2012 and 2013 (July, August, September) and from different fishing areas (east, northeast, south and southeast) were examined. In order to assess how well the raw material is suitable for processing high-quality products for human consumption, the mackerel was measured in terms of water and fat content, fatty acid composition, color, coloration and free fatty acids. In general, the mackerel collected in the summer of 2012 was of better quality than mackerel from 2013. The results also indicated a variability between fishing months in terms of fat content and the progress of development. Mackerel caught in the middle of the season had the lowest developmental value, indicating that this mackerel is best suited for processing high-quality products for human consumption.

Atlantic mackerel (Scomber scombrus) appears in Icelandic waters during its heavy feeding period, resulting in variation in mackerel products quality. Fish caught at different season during the summers of 2012 and 2013 (July, August, September) and at different sites of the Icelandic fishing area (East, Northeast, South and Southeast) were analyzed. Measurements of lipid and water content, fatty acid composition, color changes, lipid hydroperoxide (PV), thiobarbituric reactive substances (TBARS) and free fatty acid (FFA) were studied with the aim of investigating whether this raw material was suitable for the production of high quality products for human consumption. In general, samples collected during the summer of 2012 showed a better condition than fish from 2013. The results indicated seasonal variation in lipid content and rancidity development. The lowest rancidity values were observed in the middle of the Icelandic catching season, indicating that this raw material was best suited for production of high quality products. Moreover, geographical variation of the mackerel catches had an impact on the saturation of the fatty acids, and appeared as follows: East> Southeast> Northeast> South.

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Reports

Influence of drying methods on the properties of dulse

Published:

01/06/2011

Authors:

Þóra Valsdóttir, Irek Klonowski

Supported by:

AVS

Contact

Þóra Valsdóttir

Project Manager

thora.valsdottir@matis.is

Influence of drying methods on the properties of dulse

Knowledge of the parameters that control the quality and properties of dried silver (Palmaria palmata) is relatively small and little is known. If the utilization of brokers is to be increased and expanded, it is important to study these variables in more detail and document them. This report presents the results of experiments whose main objective was to compare the effects of three different drying methods on the nutritional value and physical properties of dried silver. The drying methods compared were solar drying, oven drying and lyophilization, as well as the effect of the effect on the sun-dried salts was assessed. Comparable changes in nutrients were measured after the drying process. The main difference in terms of drying methods was detected in the amount of vitamin C. There was a noticeable difference in color and texture. Taste properties were not measured but it is believed that there is some difference. Despite the fact that the results gave certain answers, many questions arose when interpreting them. There is therefore a need to acquire more knowledge about the properties of silver and their interaction with different processing factors.

The influence of three different drying methods on selected nutritional and physiochemical properties of dulse were compared; sun drying, oven drying and freeze drying. Similar influence was found on nutritional components. The main difference was found on vitamin C retention. Difference was found as well in color and texture. Flavor characteristics were not analyzed, however some differences are expected. Despite giving some answers, the results raised many questions on their interpretation. There is a need for extended knowledge on the properties of dulse and their interplay with different processing parameters.

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