The distribution of herring in the northern North Sea, derived from an acoustic survey in 1992, was studied for relationships with sea-surface salinity and temperature. Spearman Rank Correlation analyses showed significant positive correlations between herring density and both variables. It is shown that herring appear to have a preference for a specific range of salinity and temperature values. Although the correlations are significant, r-square values are relatively low. It is suggested that the relationship between herring distribution, and salinity and temperature is likely to be indirect, possibly through effects on biological production. Sea surface salinities and temperatures are used to map the presence of mixed and stratified areas, and hence the existence of hydrofronts and current influence. Herring appear to concentrate at, or near such boundary areas, which are associated with high productivity.