Climate change and the migratory pattern for Norwegian spring-spawning herring : implications for management

Abstract

Norwegian spring-spawning herring (Clupea harengus) has been an important source of food for centuries, mainly for Norway, Iceland and Russia, but also for other European countries. Herring is a migratory fish stock, and during the last 50 years the migratory pattern has changed several times. There seems to be a connection between altering climatic conditions and the size of fish, yearclass strength and the migratory pattern. The distribution and the changing migratory pattern takes on significance for the international management of the stock. The changing judicial status of the herring has caused problems and conflicts between the parties involved in the fishery. Investigating whether the change is due to over fishing or to environmental causes, or a combination of both, was one of the objectives of the analysis. Furthermore, we have looked at the processes involved in finding solutions to the problem of managing straddling stocks.