Rapport nr 138: Undersökning av fiskbestånden i Markusbölefjärden och Vargsundet 2014

• Main Author: WIKLUND, H
• Format: Report
• Language: Swedish
• Published: Åbo Akademi, Husö biologiska station 2014
• Subjects: Burbot; Lota lota; lota
• Online Access: http://www.doria.fi/handle/10024/167365

In summer 2014, the ecological status of the fish community in the lakes Markusbölefjärden and Vargsundet on the Åland Islands was investigated according to the EU Water Framework Directive. Bottom-set gillnets were used for fishing and hydrographical parameters were measured at the fishing sites. The number of bottom-set gillnets was higher than in the earlier investigations of lakes on Åland. In the Lake Vargsundet, a vertical profile was also sampled using pelagic gillnets. The ecological status of the lakes was classified as high, good, moderate, poor or bad. The ecological status of the fish community in the Lake Markusbölefjärden was classified as good, and in the Lake Vargsundet it was classified as high. One indicator species for high water quality, burbot (Lota lota L.) was found in the Lake Vargsundet. Variables used in previous investigations, such as fish community, physical-chemical factors, phytoplankton, aquatic plants and benthos, were included in the current overall classification of the lakes. Some of the values of the previous investigations were recalculated according to the new reference values so that they could be compared with the values from 2014. The resulting overall classification gave the Lake Markusbölefjärden a moderate ecological status and the Lake Vargsundet a good ecological status. As a recommendation for future investigations, use of gillnets by European standard protocol, instead of gillnets used in this investigation (Surveynet Coastal), is advised.