Variability of physical factors relevant to fisheries production in the Mediterranean Sea, North Sea and Baltic Sea

摘要

Recent publications have shown that river runoff and wind mixing are two major environmental factors affecting productivity of fish populations in subtropical and tropical areas, as opposed to water temperature in colder waters. In the present paper, we compare the variability of seawater temperature, river runoff and wind mixing in three different seas: a subtropical sea (the Mediterranean) and two cold seas (the North Sea and the Baltic). Temperature variability decreased from colder to warmer areas. The highest temporal variability in the river runoff corresponded to rivers flowing into the Mediterranean, and the lowest corresponded to rivers flowing into the North Sea and the Baltic Sea. The variability in the wind mixing index (cube of the wind speed) depended on the area under consideration, and attained maximum values in the Cap Bear station (northwestern Mediterranean). The effect of these regional variability differences in environmental factors on fisheries production is briefly discussed.