| Summary: | Herring are long-lived multiple spawners exhibiting strong variation in reproductive and recruitment success between years. They tend to adopt low-risk, preferred-conservative strategies; for example, shifts to alternative overwintering areas do not take place until there are large benefits. At the same time, herring is an extremely flexible species, displaying considerable plasticity in migratory behaviour. Migration patterns of herring have been investigated over many years. Most studies are however, descriptive and little is published that analyses the factors and mechanisms that govern spatial dynamics. In this paper we try to interpret the existing observations from an ecological and evolutionary perspective, emphasising proximate mechanisms that restrict the extent to which herring are capable of attaining an optimal distribution. Focus is directed to observations and literature on the Norwegian spring spawning herring.
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