Reviews in Fish Biology and Fisheries 13: 1–26, 2003.
© 2003 Kluwer Academic Publishers. Printed in the Netherlands.
Linking population genetics and growth properties of Atlantic cod
Albert K. Imsland
ora Bartels J
Akvaplan-niva, Iceland Ofﬁce, Akralind 4, 201 K´opavogi, Iceland (Phone: +354 562 58 00; Fax: +354 564 58 01;
Department of Fisheries and Marine Biology, University of Bergen,
5020 Bergen, Norway
Accepted 8 May 2003
Abstract page 1
Population genetics of cod
Environmental regulation of growth in cod
Genetic studies of Atlantic cod on a small geographical scale 4
Why do mitochondrial and nuclear DNA studies give such contradictory results?
Population separation and growth differences 14
Variation in life history parameters in different population units
Do life history parameters vary between different cod stocks?
Genetic properties and growth performance: growth properties of different cod genotypes 18
Syp I genotypes and other RFLP genotypes
Possible mechanisms behind growth differences 19
Differences in population growth performance
Environmental inﬂuences on genetic variation in growth rates
Individual genetically-based growth differences
Key words: Atlantic cod, Gadus morhua, genetically-based growth, life histories, population genetics, spawning
It is strongly implicated that cod in the North Atlantic Ocean is sub-structured at a small geographic scale exempli-
ﬁed by studies from Canadian, Icelandic, and Norwegian waters. In the ﬁrst part of this review, we reviewed
population genetics studies in these three areas and our conclusion is that, despite some inconsistencies in the
numerous genetic studies of cod in Norwegian and Icelandic waters, and the northwest Atlantic, these studies
illustrate that cod in the investigated areas consists of several distinct populations, both within and between areas.
However, to understand the contradictory results obtained in some of the studies discussed in this review, more
knowledge about the inﬂuence of natural selection, mutation, and genetic drift on the genetic material of cod is
necessary. Such knowledge could guide us to the markers giving the best illustration of the genetic structure in
these areas. Identifying and genetically characterizing wild stocks are essential steps for their conservation, since