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Pike

Esox lucius 

Photo: Le Carlsson/AzotePhoto: Le Carlsson/Azote

Pike is one of several freshwater fishes inhabiting the Baltic Sea. The species naturally prefer the less saline areas and thus colonize mostly the coastal areas.

Conservation genetic management advice

  • Genetically healthy pike populations in the Baltic Sea require the maintenance of spawning areas along the coastline as well as in adjacent freshwater bodies.
  • In order to maintain, support or restore local pike populations it is important to restaurate spawning grounds in some areas. This will also help maintain the possibilities for genetic exchange between areas, and thus reduce loss of genetic variation.
  • The possibility for genetic exchange among spawning areas is important. Thus, both local scale and large scale management are needed for pike.
  • For the brackish spawning pike, particular attention should be paid to areas with clear genetic distinction, see “Knowledge on genetics in the Baltic” below.
  • Stocking should be avoided except to conserve weak populations. Such conservation releases should use genetically similar populations, primarily located close to the restocking site. Releases should be documented carefully and be monitored genetically.

Threats to genetic biodiversity

Decline and/or loss of local populations could risk the loss of genetic variation, and break the genetic exchange between spawning grounds. The stocking activities that occur in some areas risk transferring non-native genetic material to natural populations, which can reduce their adaptive potential. Such stocking activities are typically poorly documented and not monitored genetically. This prohibits finding out their potential effects.

Knowledge on genetics in the Baltic (2017)

The genetic pattern differ between pike spawning in coastal brackish water as compared to pike that migrate up into in adjacent freshwater areas to spawn. Freshwater spawners show much stronger genetic substructuring with larger genetic differences between populations.

The brackish spawning pike show relatively weak genetic substructuring. Obviously, genetic exchange occur over large geographic distances including, potentially across the Baltic via the Islands of Åland. However, genetic core areas with particularly distinct and genetically variable brackish populations occur in the Estonian and Stockholm Archipelagos, in the Bothnian Bay and as well as around the Swedish Quark.

The species has declined locally in some areas around the Baltic, for instance the Kalmar Sund region. This can result in loss of genetic variation, but since genetic diversity is not monitored little is known of such potential effects.

References

CONTRIBUTORS

Lovisa Wennerström
lovisa.wennerstrom@zoologi.su.se

Linda Laikre
linda.laikre@popgen.su.se

Nils Ryman
nils.ryman@popgen.su.se

Additional information

The pike is subject to commercial and sport fishery in coastal areas all around the Baltic. Data is currently missing on whether this fishery is affecting the genetic diversity of the species.

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