|Transition in Pollution Level of Fished in Minamata Bay area|
Source: Kumamoto prefecture 1976
Minamata bay area, various types of investigations and research activities have been
carried out with respect to environmental pollution such as water quality, bottom
sediment, fish and other marine creatures, hair sample etc.
As a result, it was concluded that continuous methylmercury exposure at the level which could cause Minamata disease existed until no later than 1968 in the Minamata area, and that after that, there has not been such exposure that could lead to the onset of Minamata disease.
In August 1997, Kumamoto Prefecture released the restaurant on intake of fish, taking apart the dividing nets from dredging area of Minamata Bay.