Thirteen years of monitoring selected biomarkers in Eelpout (<i>Zoarces viviparus</i>) at reference site in the Fjällbacka Archipelago on the Swedish West Coast

Abstract

Several biomarkers in female and male eelpout (Zoarces viviparus) were measured at Fjällbacka, a reference site on the Swedish west coast from 1989 to 2001. Standardised procedures for sampling and measurements were used. Some of the biomarkers were largely stable through the years, for example, condition factor, blood plasma chloride concentration, white blood cell count, percentage of lymphocytes, activities of glutathione-S-transferase and glutathione reductase. Others showed greater variations but not significant trends, for example, percentage of granulocytes and activity of catalase and ethoxyresorufin-O-deethylase activity. Three variables in female eelpout showed a statistically significant downward trend from 1989 to 2001, hematocrit, body weight and length. The change in hematocrit was probably related to decreased stress due to improved sampling techniques, but the reason for changes in weight and length remain unknown. There is a need to evaluate the area for pollutants. The results indicate that there have not been any major large-scale changes in the aquatic environment affecting the fish health at the investigated site.