The mercury levels in various fish species, such as pike, pikeperch, perch and burbot are high in Koitere. Over several years, they have exceeded the limits of health recommendations for food. The limit for pike is 1,0 mg/kg. For other species the limit is 0,5 mg/kg. Large and heavy fish are likely to contain more mercury than small fish.
• The mercury levels of pike have been measured since 1972. In 2000, 2001, 2012 and 2018, average levels exceeded 1.0 mg / kg. Studies were conducted over five different years.
• The levels of perch were measured in 2000 and 2012, with average levels exceeding 0.5 mg / kg
• The levels of burbot were measured in 1980 and 2000, with average levels exceeding 0.5 mg / kg
Hydropower-caused water level regulation, dark and humus-rich water, forestry and drained peatlands increase the mercury levels of Koitere.