Folkvord, A., G. Blom, J.V. Helvik, B.I. Holmqvist, A. Johannessen, E. Otterlei & S.O. Stefansson 1998. Teori- og eksperimentbasert studie av rekruttering hos marin fisk - Sluttrapport fra del I av strategisk program. IFM Rapport 7:1-46.


A central issue in fisheries science the last 100 years has been the understanding of why commercial fish species, such as cod and herring, are subject to large variations in stock levels. Nearly a century ago it was discovered that the year-to-year variations in recruitment of the fish stocks was one of the main causes of the variation in stock levels. There is still no consensus, however, of why and how these variations come about, and extensive process oriented studies have generally not been carried out due to:

- the lack of available tools for assessing age, growth and nutritional status

- new fundamental biological theory in ecological modelling has been developed the last ten years

Today there are both methods and equipment available to accomplish process oriented studies. Based on pilot studies it is possible to develop models which can simulate stage- and size-specific vulnerability to starvation and predation. These models can in turn be evaluated with additional experiments under controlled conditions. In this manner one can integrate modelling with experimental studies with the aim of testing specific recruitment hypotheses in the field.

This report includes results from the first part of a strategic programme on theory and experiment based studies on recruitment in marine fish.

Updated 3. March 1999 by Arild Folkvord