The mercury problem and fishing in Finland

Abstract

The extent of mercury pollution in Finnish watercourses was first realized in 1967 when significantly elevated mercury concentrations were found in fishes of prey from several lakes and rivers. The mercury originated mainly from the pulp and chloralkali industries, and fishermen sustained heavy losses when both fish consumption and the price of fish declined.

The use of mercury in the pulp industry ended in 1968 and the discharge of mercury from the chloralkali plants has decreased significantly, but the decrease in the mercury content of the fish has been slow. The mercury problem was recently accentuated when elevated mercury levels were also found in many lakes without any known industrial mercury discharge. The highest concentrations occurred in man-made lakes, where the water level fluctuations are great. In most of the man-made lakes in northern and western Finland the fishes of prey (pike, perch and burbot) are unsuitable for human consumption because of their high mercury content. The construction of drainage ditches in forests and bogs is also assumed to be responsible for elevated mercury concentrations in Finnish lakes. The fishermens’ losses caused by decreased sales, reduced prices and the costs for unused equipment amount to several million Finnish Marks.