Cyclic changes of climate and major commercial stocks of the Barents Sea

Abstract

Spectral analysis of 100-year time series of Arctic surface temperature (Arctic dT), mean temperature of 200-m water column along the Kola meridian and global surface temperature anomaly (Global dT) was performed. It is shown that climatic indices of the Arctic region undergo long-term 50–70-year fluctuations similar to fluctuations of Global dT and Arctic dT for the last 1500-year reconstructed period and the recent 140 years of instrumental measurements. Long-term changes of Atlantic spring-spawning herring and Northeast Arctic cod commercial stocks also show 50–70-year fluctuations that are synchronous with the fluctuations of climatic indices. A simple stochastic model is suggested that makes it possible to predict the probable trends of basic climatic indices and populations of major commercial fish species for up to 20–30 years into the future. The results obtained also elucidate the old discussion: which factor is more influential on the longterm fluctuations of major commercial stocks, climate or commercial fisheries? We think that what we have learned is that climate is of priority, but which factor(s) cause(s) what, for which species, seems as yet unanswered.

Keywords:

• Climate cycles
• cod stock fluctuations
• herring stock fluctuations