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Atlantic herring - Clupea harengus 

 MANAGEMENT ISSUES

Summary of issues specific to the Baltic region

Preliminary evidence for local adaptation indicates that there may be a risk of loss of local adaptation. So far, it looks like the Baltic population structure could be continuous, so co-ordinated management at a local scale is preferable until further information is available.

Current management regulations

Presently ICES identifies five herring stocks in the Baltic: Bothnian Bay, Bothnian Sea, two in the baltic proper and one stock comprising Western Baltic, Kattegat and Skagerrak herring. The Western Baltic stock, e.g. spawning in Rüegen, undertake feeding migrations to northern Skagerrak. 

Gaps between management and scientific evidence

More genetic information is required for a comprehensive management. Genetic studies indicate that there may be resident distinct subpopulations in inner danish waters and along the Skagerrak coast that are managed together with migratory herring spawning in Rüegen. 

 

GENETIC INFORMATION (January 2012)

Species Number of genetic studies Baltic population structure Baltic population diversity Baltic effective population size Temporal data Genetic risks Management recommendations
Atlantic herring >10 Continuous High Unknown Some temporal change Loss of local adaptation Co-ordinated local-scale management until further studies into differentiation are completed.

 

Mapping Baltic Sea genetic biodiversity

These maps show mean differentiation of populations, and location of major genetic discontinuities in the Atlantic herring (Clupea harengus).

        

Fig 1. Barriers of gene flow

Three major barriers to genetic exchange was observed for the Atlantic herring.

Full lines are barriers supported by at least half of the scored gene loci. Dotted lines are barriers supported by less than half of the scored loci.

A major genetic barrier is located at the entrance of the Baltic Sea for herring.

 

Fig 2. Genetic divergence

The degree of genetic divergence among populations was classified.

Red dots: populations more genetically divergent than the average divergence among populations.

Blue dots: populations less genetically divergent than the average.

Peripheral populations are generally more diverged (more genetically unique) than central populations.

These are preliminary results (January 2012). Full and additional results on Baltic Sea genetic biodiversity will be presented in a coming scientific report. 

Summary of key published genetic information

Current knowledge of herring population differentiation comes from a number of studies looking at a small number of microsatellite markers, allozymes, and mtDNA. Although there are a reasonably large number of studies over the last decade, the genetic resources available remain limited.

There appears to be low levels of genetic differentiation between populations in the North Sea and the Baltic Sea (Bekkevold et al. 2005). Some studies with a small number of microsatellite markers have uncovered a low degree of population differentiation within the Baltic, which appears to co-vary with salinity and sea surface temperature (Jørgensen et al. 2005).

However, recent studies using a microsatellite marker that may be linked to an unknown functional gene have shown that there is a gradient in frequency of a particular allele from the inner Baltic to the North Sea (André et al. 2011, Larsson et al. 2007). This particular marker also shows much higher levels of divergence within the Baltic than has been found previously. This indicates that there could be some finer-scale differences in this species within the Baltic, which may be linked to adaptation to environmental gradients such as salinity. This has sparked a number of ongoing studies, which are looking more closely at population differentiation and functional genes.

 

Key publications

André C, Larsson LC, Laikre L, Bekkevold D, Brigham J, Carvalho GR, Dahlgren TG, Hutchinson WF, Mariani S, Mudde K, Ruzzante DE and Ryman N (2011) Detecting population structure in a high gene-flow species, Atlantic herring (Clupea harengus): direct, simultaneous evaluation of neutral vs putatively selected loci. Heredity 106, 270–280. PubMed

Bekkevold D, André C, Dahlgren TG, Clausen LAW, Tortensen E, Mosegaard H, Carvalho GR, Christensen TB, Norlinder E, Ruzzante DE (2005) Environmental correlates of population differentiation in Altantic herring. Evolution 59, 2656-2668. PubMed

Jørgensen HBH, Hansen MM, Bekkevold D, Ruzzante DE, Loeschcke V (2005) Marine landscapes and population genetic structure of herring (Clupea harengus L.) in the Baltic Sea. Molecular Ecology 14, 3219-3234. PubMed

Larsson LC, Laikre L, Palm S, André C, Carbalho GR, Ryman N (2007) Concordance of allozyme and microsatellite differentiation in a marine fish, but evidence of selection at a microsatellite locus. Molecular Ecology 16, 1135-1147. PubMed

Ryman N, Lagercrantz U, Andersson L, Chakraborty R, Rosenberg R (1984). Lack of correspondence between genetic and morphologic variability patterns in Atlantic herring. Heredity 53: 687-704. 

More information about herring at IUCN  - International Union for Conservation of Nature Resources

 

CONTRIBUTORS (January 2012)
Amber Teacher, University of Helsinki, Finland

Carl André, University of Gothenburg, Sweden
Linda Laikre and Lovisa Wennerström, Stockholm University, Sweden


Responsible editor: Carl André, University of Gothenburg, Sweden
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