There are three lamprey species in Finland. European river lamprey (Lampetra fluviatilis) is common along the coast of Finland and 28 rivers are known to support spawning populations while landlocked river lamprey populations exist in three watercourses. European brook lamprey (Lampetra planed) is common in freshwater all over the country, and sea lamprey (Petromyzon marinus) has been reported off the Finnish coast only 19 times since 1854. Food of the river lamprey and landlocked river lamprey includes valuable fish species such as herring, sprat, and vendace, but no effects on the fish stocks have been reported. River lamprey catch in Finnish coastal rivers make up about 2–2.5 million individuals (100 t) and lampreys are used only for human consumption. The fishing season begins in August and ends in February. Environmental changes in rivers (dams, pollution, etc.) have caused great damage to river lamprey populations. Successful attempts have been made to promote spawning by transporting lampreys over the dams. Landlocked river lamprey, brook lamprey, and sea lamprey are of no economic significance in Finland.Key words: sea lamprey, river lamprey, brook lamprey, distribution, Finland, life history, fisheries, management

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Climate change scenarios concerning the Baltic Sea predict increase in surface water temperatures. Pikeperch (Sander lucioperca (L.)) inhabits the coastal areas of the northern Baltic Sea and is an important fish species for the Finnish fisheries. The year-class strength of pikeperch varies strongly between years and significantly depends on water temperature. We aimed to study the effects of changing temperature conditions on pikeperch fisheries and distribution based on commercial catch data from the period 1980-2008 in the Finnish coastal areas of the Baltic Sea. The results indicated that warmer summers will produce stronger pikeperch year-classes that consequently contribute significantly to the future catches. The average temperature in June-July explained 40% of the variation in the year-class catches in the Gulf of Finland and 73% in July-August in the Archipelago Sea. During the study period, the distribution of pikeperch catches expanded toward north along the coasts of the Bothnian Sea.

Many recent studies have stressed density-dependent regulation mechanisms in oscillating vendace (Coregonus albula) populations. Long-term studies on the population dynamics of vendace have been hampered by the difficulty of obtaining reliable estimates of year-class sizes. Data collected from Lake Pyhäjärvi (Southwest Finland) during 1971–91 allowed relatively accurate analysis of vendace abundance changes. In the winters of 1979–91, daily catch statistics were collected from professional fishermen. Species, age, and size composition were analysed from regular catch samples. We estimated the size of the vendace population from the decrease in the CPUE during 10 winters. For the remaining 10 years, estimates were based on the relationship between the numbers of a year-class in autumn and mean individual growth rate. A 2-yr cycle was the most conspicuous feature of the data implying density-dependent regulation. We suggest that in Lake Pyhäjärvi the basic model producing a persistent 2-yr cycle is the asymmetrical food competition between age groups.

In 1989-1998, vendace larvae Coregonus albula were sampled in Finnish lakes following a stratified random sampling design. The abundance of young-of-the-year vendace after the first growing season was estimated using catch-per-unit-effort statistics. The number or total area of nursery places hardly limited the recruitment of vendace in the study lakes. The major proportion of prerecruit mortality of vendace occurred in the larval phase and larval sampling produced significant information on young-of-the-year survival. Although larval abundances and recruitment were clearly associated only in Lake Onkamo, generally high larval abundance was needed to produce high number of recruits. 2000 The Fisheries Society of the British Isles

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The conservation of biodiversity in aquatic habitats has become an increasingly important challenge in the management of water resources. In addition to the complexity of the lake fishery and the management structure, the popularity of gill net fishing, in particular, has brought problems when re‐establishing populations of Arctic charr, Salvelinus alpinus (L.), collecting genetically sustainable numbers of spawners of the land‐locked salmon, Salmo salar m. sebago (Girard), and increasing the population of the Saimaa ringed seal, Phoca hispida saimensis (Nordq.) to a sustainable level in the Vuoksi watercourse, south‐east Finland. The attitudes towards protection among the users and other interested parties vary. In order to enhance the coexistence of the lake fishery and endangered species over large water areas, improved institutional linkages are needed among the local, regional and governmental levels of the fragmented decision‐making regime. Environmental interests should also be integrated into the communication structure.