The concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF) were studied in two fish species, Baltic herring (Clupea harengus membras L.) and sprat (Sprattus sprattus balticus Schn.), in Estonian coastal waters and the open Baltic Sea in spring and autumn 2002. For analyses, 493 individual herring were combined to 20 pools and 246 individual sprat were combined to 8 pools. A positive correlation between the PCDD/PCDF concentration and age of herring (length, weight) both in spring and autumn was found to be statistically reliable. Bioaccumulation of PCDD/PCDF into the organism of fish from the studied waters depends on the age, length, and sex of the fish, and the fishing ground. [ABSTRACT FROM AUTHOR]