Freshwater fishes, their biodiversity, habitats and fisheries in the Nordic countries

Abstract

Finland, Norway and Sweden have in total about 126500 lakes larger than four hectares. In Finland and Sweden, approximately 10% of the surface area is freshwater; whereas in Norway, it is about 6%. Altogether 56 fish species are reproducing in the Nordic freshwaters, including four lamprey species. Due to geographical differences, the freshwater fish fauna differs considerably in the northern and southern parts; but species richness increases also from west to east. The proportion of recreational fishermen in Norway, Finland and Sweden was about 50%, 40% and 27 %, respectively, in 2004. Professional freshwater fishing is declining, but is still important in some lakes in Finland and Sweden. In all three countries, fishing rights belong to the water or land owner, with some exceptions. Water quality has improved in recent decades due to decreased nutrient loads from point sources, but the limitation of scattered nutrient loads has been less successful. This development can also be seen in the responses of fish communities. Some 30–40 years ago, waters close to many cities or industrial plants were heavily polluted and had only limited recreational or fisheries value. Recently, they are often inhabited by healthy fish populations. On the other hand, there are many highly eutrophic lakes in agricultural areas of southern and western Finland and Sweden that regularly suffer from algal blooms and high biomasses of cyprinid fish. The increasing acidification problem of oligotrophic lakes was related to long distance air pollution in recent years, but the situation has now improved. Lake regulation impacts the littoral ecosystems in hundreds of lakes and causes considerable negative impacts on feeding and reproduction areas for fish. The main measure used for compensating the damaged fish numbers has been stocking. Many large rivers have been modified for hydropower production. Most activities of fish habitat restoration are directed at rivers. Fisheries management includes several tools: regulations on use and structure of fishing gear, temporal and regional fishing restrictions, the size limits of target fish, the limitations of fishing efficiency, and amount of catch. The general goal is to meet the principles of sustainable use of natural resources.