Effects of eutrophication on fish and fisheries in Finnish lakes: a survey based on random sampling

• Published in: Fisheries Management and Ecology
• Main Authors: TAMMI, J., LAPPALAINEN, A., MANNIO, J., RASK, M., VUORENMAA, J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1999
• Subjects: Burbot; Lota lota; lota
• Online Access: http://dx.doi.org/10.1046/j.1365-2400.1999.00152.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1365-2400.1999.00152.x; https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-2400.1999.00152.x

Abstract The effects of eutrophication on fish and fisheries in Finnish lakes were determined by an extensive lake survey conducted in 1995 and 1996. The study lakes (873) were chosen by stratified random sampling from all Finnish lakes with a surface area ≥ 0.04 km 2 (29 515 lakes in all). The chemical parameters of the lake water were determined for water samples taken in autumn 1995. Information on the fish stocks of the study lakes was collected by means of a postal questionnaire sent to local fishing authorities and lake owners. The results show that the fish community structure is cyprinid dominated, reflecting eutrophication in 2100 lakes (7% of all the target lakes). Strong fouling of the fishing gear, as well as a great abundance of unwanted species in the catch of passive gears, were considered to be a continuous problem in more than 10% of the lakes. Roach, Rutilus rutilus (L.), and bream, Abramis brama (L.), were the most common species to have increased in abundance in the study lakes, whereas burbot, Lota lota (L.), and vendace, Coregonus albula (L.), decreased, especially in highly eutrophic lakes. High total phosphorus and cyprinid dominance in lakes were found mainly in the most intensive agricultural regions in the western and southern parts of Finland.