The main objective is to study the present state of the stock of fish in the Eastern Gulf of Finland and the rivers that empty into it by 1) establishing a fish monitoring area in the Haapasaari archipelago and 2) studying the fish stock in the rivers that empty into Eastern Gulf of Finland on the Finnish and Russian side of the border.The information acquired from monitoring the Haapasaari archipelago and the rivers can be used for 1) assessing the effects of oil and chemical accidents, 2) monitoring slower changes in the fish stock, 3) classifying the ecological state as required in the EU framework directive and 4) comparing the area with similar international monitoring areas.