Clupea harengus Archives

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.

Preliminary project for research on the genetic composition of Icelandic herring compared to other stocks in the Northeast Atlantic: Biological diversity and processing properties / A pilot study on the multidisciplinary approach for the genetic stock identification of herring in the Northeast Atlantic: Biodiversity, functional and chemical properties

Post author By admin
Post date 01/10/2013

Published:

01/10/2013

Authors:

Sigurlaug Skírnisdóttir, Guðbjörg Ólafsdóttir, Sarah Helyar, Christophe Pampoulie, Guðmundur J. Óskarsson, Ásbjörn Jónsson, Jan Arge Jacobsen, Aril Slotte, Hóraldur Joensen, Henrik Hauch Nielsen, Lísa Libungan, Sigurjón Arason, Sindri Sigurðsson, Sigríður Hjörleifsdóttir, Anna K. Daníelsdóttir

Supported by:

Fisheries Project Fund, AG ‐ Fisk, Faroese Fisheries Research Fund, Research Studies Fund, Student Innovation Fund

Contact

Guðbjörg Ólafsdóttir

Specialist

gudbjorg.olafsdottir@matis.is

Preliminary project for research on the genetic composition of Icelandic herring compared to other stocks in the Northeast Atlantic: Biological diversity and processing properties / A pilot study on the multidisciplinary approach for the genetic stock identification of herring in the Northeast Atlantic: Biodiversity, functional and chemical properties

The purpose of the project was to:

· Develop a genetic analysis set with 20-25 genetic markers to assess the genetic composition and stock structure of herring in the Northeast Atlantic

· Use genetic makeup, milling and other biological factors to differentiate strains

· Study the relationship between stock units and the processing properties of herring

Knowledge of herring stocks is of great importance for the sustainable utilization and management of herring fisheries. A key factor for sustainable fisheries management and quota allocation is to know what stock units are in the fishing areas and how large they are. In this project, approx. 4,500 samples collected from nine possible stock units in the Northeast Atlantic in the years 2008 - 2012 (off Iceland, Norway, the Faroe Islands and Scotland). This extensive and extensive sample collection will then be used in further research projects. The results of a genetic analysis with 24 genetic markers showed that local herring stocks in fjords in Norway were significantly different from all other stock units. However, no significant differences were found for the possible stem units. Other more sensitive methods, such as DNA monopoly analysis (SNPs), may be able to differentiate between the strains, but this research has already begun in a new follow-up project. The biological information collected in the project did not differentiate between possible stem units. Studies of the Icelandic summer spawning herring and the Norwegian-Icelandic spring spawning herring showed differences in body color, water and fat content as well as stage of puberty and weight. No results have been obtained from the mill analyzes, but they will be published in connection with a doctoral project at the University of Iceland.

The aim of the project was:

· To develop a genetic approach based on 20-25 microsatellite loci to study the genetic variation of herring stocks in the Northeast Atlantic Ocean

· To use genetic, biological and otolith characters as discriminating parameters for stock identification

· To analyze physicochemical characteristics of different herring stocks

Sustainable fisheries management and quota decisions made by authorities are based on knowledge on fish stock structures and their sizes. Herring is a highly migratory fish species, and therefore it is likely to show low genetic differences among stocks. The mixed stock herring fishery creates considerable problems for the industry and the management of the stocks. In this project more than 4,500 individuals were sampled from 9 putative herring stocks in the Northeast Atlantic Ocean during the years 2008 and 2012. The sampling accomplished in the project is extensive and valuable for future research projects. The results of the genetic study based on 24 microsatellite genetic loci showed that the local Norwegian fjord stocks were significantly different from all other putative stocks. The other Northeast Atlantic herring stock units were not found to be significantly different. Power analyzes performed during this study revealed that sampling scheme, protocols and genetic design were sufficient to detect any level of genetic differentiation around 0.001. Therefore, a more sensitive type of genetic markers are needed for the problem addressed, such as SNPs (single nucleotide polymorphism) and that work has already started. Biological parameters alone did not have enough discriminating power for stock identification. The Icelandic summer ‐ spawning herring (ISSH) and the Norwegian spring ‐ spawning herring (NSSH) differed mainly in color and water / fat content. The herring from the two stocks were also found to be different in relation to maturity and weight. The methodology of otolith microstructure analyzes and their results will be published later in a PhD thesis at University of Iceland.

Report closed until 01.02.2015

Guðbjörg Ólafsdóttir

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