On long-term changes in abiotic and biotic conditions

Results of oceanographic investigations affect long-range forecasts of atmospheric and hydrospheric temperature and of ice conditions, and also predictions of year-class strength of commercial species and of substantial changes in their distribution. Biotic phenomena are functionally related to abiotic conditions. The strength of year class of commercial species, annual recruitment to fish populations and their total stocks are closely related to annual and long-term variation in abiotic conditions. The topic is discussed in detail, considering in particular calculation of commercial fish stocks by summation of oceanographic indices for the birth years of year classes on which the fishery is based.