The fish communities of three bays on Åland

The fish communities of three areas of sheltered bays were studied from July to September, 1992, using Swedish standard gill- nets. Area 1, in NW Åland with three stations from Orrfjärden, a large bay in the inner archipelago with brackish water, to Vandöfjärden that is nearly isolated from the sea, with almost oligohalin water. Area 2, in southern Åland is a sheltered bay connected to the outer archipelago through a sound, and area 3, in SE Åland (Lumparn) consisting of some sheltered bays and inlets. Area 1 was dominated by Cyprinides (roach and white bream) to about 70 %, (perch about 20 %). Vandöfjärden with its low salinity differed from the two other stations with its low biomass per effort and by the abundance of juvenile smelt (osmerus eperlanus). Area 2, Bursfjärden, was special with its close relationship to the open see, with species as Baltic herring that usually belonge to the outher archipelago. The dominating species was roach, about 45 %, when perch and Baltic herring of about 20 % each. The inner- most part of area 3, Ämnäsviken, was dominated by perch allthough the high biomass per effort and the population structure of roach indicated some eutrofication. Station 7, Ytterbyviken in the same area, was propably in a later phase of eutrofication, with low biomass per effort, and almost total absence of juvenile perch. Only a few species were represented in food choice analysis on perch caught at this station. In total, 12 species caught on gill- nets were recorded, reflecting the natural Baltic archipelago fish communities, in spite of local eutrophication