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Whitefish - Coregonus lavaretus 

 

 

MANAGEMENT ISSUES

Summary of issues specific to the Baltic region

Due to its low level of salinity, the Baltic Sea harbors a unique mix of marine and freshwater species that have been adapted to brackishwater conditions and in general, salinity is one of the most important environmental factors shaping biodiversity in the Baltic Sea. Whitefish is an example of a fish species in which distinct populations that spawn in different salinities, often termed ecotypes, have been recognized. Based on current knowledge, there are river-, lake-, and sea-spawning whitefish in the Baltic Sea and can be anadromous (i.e. live in the sea and migrate in freshwater to spawn) or not. As whitefish is of commercial and recreational fishing importance, describing and understanding genetic variation is necessary to improve restocking and other management practices.

Current management regulations

To compensate the declining natural reserves, millions of one-year old whitefish juveniles are released annually into the Baltic Sea. Fishing regulations concerning methods like trawling that removes young whitefish from the populations have been discussed repeatedly but thus far have been applied only regionally (mostly in the Northern Baltic Sea).

Gaps between management and scientific evidence

Management efforts regarding whitefish have proven unsuccessful, with only a small proportion of individuals surviving, possibly because only a fraction of the stocked whitefish populations are being supplemented by fish originating from native habitats. For instance, the vast majority of the fish released to the coastal waters of the Baltic Sea do not belong to sea-spawning ecotype but rather represent anadromous (river-spawning) or even unknown ecotype. Scientific evidence suggests that although large-scale stocking and supportive releases enable to maintain high fishing pressure, such activities pose a real threat to natural breeding populations that still remain in the wild. 

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
Whitefish 10 Structured, medium to high differentiation High Unknown Available for some hatchery populations
Loss of local adaptation, genetic swamping 
Improving conditions for natural spawning,  fishing regulations, re-stocking with local broodstocks 

 

Summary of key published genetic information

Mitochondrial and nuclear data indicate that whitefish of the Baltic Sea are genetically unique compared to elsewhere in Europe. Whitefish population in the Baltic Sea show relatively low levels of genetic differentiation based on neutral molecular markers. However, analysis at phenotypic and gene expression level suggests local adaptation of sea-spawning populations. Based on neutral microsatellite markers, wild populations have been shown to have slightly higher genetic diversity than hatchery-reared populations. 

Key publications

  1. Hansen M.M., Mensberg K.L.D., Berg S.  Postglacial recolonization patterns and genetic relationsships among whitefish (Coregonus sp.) populations in Denmark, inferred from mitochondrial DNA and microsatellite markers. Molecular Ecology, (1999) 8: 239-252.
  2. Olsson, J., Florin, A.-B., Mo, K., Aho, T., Ryman, N. Genetic structure of whitefish (Coregonus maraena) in the Baltic Sea. Estuarine, Coastal and Shelf Science. (2012) 97, 104-113, doi:10.1016/j.ecss.2011.11.032
  3. Papakostas S., Vasemägi A., Peil L., Himberg M., Vähä J-P., Primmer C.R. A proteomics approach reveals divergent molecular responses to salinity in populations of European wwhitefish (Coregonus lavaretus). Molecular Ecology (in press)
  4. Säisä M., Rönn J., Aho T., Björklund M., Pasanen P., Koljonen M-L.  Genetic differentiation among European whitefish ecotypes based on microsatellite data. Hereditas, (2008) 145: 69-83. 
  5. Østbye K., Bernatchez L., Næsje T.F., Himberg K.-J.M., Hindar K. Evolutionary history of the European whitefish Coregonus lavaretus (L.) species complex as inferred from mtDNA phylogeography and gill-raker numbers. Molecular Ecology,  (2005) 14: 4371-4387.

More information about whitefish at IUCN - International Union for Conservation of Natural Resources  

 

CONTRIBUTORS (January 2012)
Craig PrimmerAnti Vasemägi and Spiros Papakostas, University of Turku, Finland
Mikael Himberg, Åbo Akademi University, Finland


Responsible editors: Craig Primmer, University of Turku, Finland
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