MEPS 302:219-232 (2005)  -  doi:10.3354/meps302219

Population dynamics of cod Gadus morhua in the North Sea region: biological density-dependent and climatic density-independent effects

Qingxian Chen1, Kung-Sik Chan2, Kyrre Lekve3, Else Torstensen4, Jakob Gjøsæter4,Geir Ottersen5,6, Nils Chr. Stenseth3,4,*

1New York State Office of Mental Health, 44 Holland Avenue, Albany, New York 12229, USA
2Department of Statistics and Actuarial Science, University of Iowa, Iowa City, Iowa 52242, USA
3Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biology, University of Oslo, PO Box 1050 Blindern, 0316 Oslo, Norway
4Institute of Marine Research, Flødevigen Marine Research Station, 4817 His, Norway
5Institute of Marine Research, PO Box 1870 Nordnes, 5817 Bergen, Norway
6Present address: Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biology, University of Oslo, PO Box 1050 Blindern, 0316 Oslo, Norway
*Corresponding author. Email:

ABSTRACT: Through the statistical modeling of monitoring data, we assess the ecological interlinkages between cod Gadus morhua L. in the North Sea, Skagerrak and Kattegat—regions which typically have been considered separate management units. The model includes both within-population density dependence (within and between age classes), as well as density-dependent effects of migration between the North Sea, Skagerrak and Kattegat. Further, the model incorporates the effects of environmental features (such as temperature and the North Atlantic Oscillation). The obtained results are discussed, both with reference to general ecological principles as well as with respect to management implication. Altogether our analysis suggests a unified management regime for the entire region including the North Sea, the open Skagerrak and Kattegat.


KEY WORDS: GAM · NAO · North Sea–Skagerrak–Kattegat system · Time-series modeling ·Transport effect


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