show Abstracthide AbstractPerch (Perca fluviatilis) has been used in biological effect monitoring in a programme for integrated coastal fish monitoring at the reference site Kvädöfjärden along the Swedish east coast, which is a site characterized by no or minor local anthropogenic influences. Using a set of physiological and biochemical endpoints (i.e., biomarkers), clear time trends for “early warning” signs of impaired health are noted in the perch from this site, possibly as a result of increased baseline pollution.