MEPS - Vol. 345 - Feature article

Gadus morhua. Cod migrations can be assessed with archival tags, which store measurements of temperature, pressure (depth) and light. Photo: Fisheries Research Services, Aberdeen

Svedäng H, Righton D, Jonsson P


Migratory behaviour of Atlantic cod Gadus morhua: natal homing is the prime stock-separating mechanism


Fish stock identification relies on our knowledge of the mechanisms involved in population structuring. Svedäng and co-workers used archival electronic tags to investigate the migrations of Atlantic cod in the eastern North Sea. Observed migratory trajectories were in agreement with the hypothesis that the cod population in this region comprises a mixture of resident and migratory stocks. Cod tagged off the eastern Skagerrak coast migrated west towards the North Sea during the spawning period in January to April, indicating a return migration to natal spawning sites. This suggests that migratory behaviour is crucial for stock integrity and that recolonisation in areas depleted of local stocks is a slow process, because it involves development of stock-specific behavioural features.


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