A long period of «herring-driven» population growth in West Norway after 1815 waned in the decade 1866–75. The material economic basis that spring herring represented was a precondition of growth. The examples in this study fit a larger picture in which weaker population growth and occasionally population decline may be used as indicators of «crisis». At the same time, this is a confirmation of the neo-classical economic micro-theory in which better opportunities for employment encourage people to move. This will be particularly true of poorly developed societies which lack welfare arrangements and insurance facilities that could have provided security for those affected. The hypothesis that Haugesund and Stavanger were the main destinations chosen by migrants is confirmed in part. At the same time, the high percentage of locally born, particularly in the small town of Skudeneshavn and Skudenes municipality, demonstrates the negative consequences for these areas as attractive destinations for migration when the herring disappeared. Mining at Visnes together with a stronger focus on farming contributed to population growth in Avdalsnes municipality, unlike other rural areas, from the middle of the 1860s. According to received migration theory, these changes in the economic conditions should have led to increased emigration. Nonetheless, rates of emigration were low in relation to other districts. The explanation is that when the herring fishery in the Karmsund area collapsed, a significant precondition was lacking – an emigrant network. This, together with straightened times, delayed the start of mass emigration from the Karmsund area.