Longitudinal Connectivity and Remedial Measures in a Swedish River

Intact longitudinal conductivity ensures that fish migrate between habitats. Here, we present our studies of longitudinal connectivity conducted from 2000-2009 as they relate to migration of trout and other species in the regulated River Emån, Sweden. Two nature-like fishways for upstream migration were constructed at Finsjö, approximately 30 km upstream of the Baltic Sea, in 2000. Based on telemetry and PIT-tag studies, we found passage efficiencies of 89%-100% for trout and 50-100 % for other species. Attraction efficiencies for trout were 50-89%. For downstream migration, 50% of the smolts and 70% of the kelts swam past both dams at Finsjö, and 15% of the smolts and 50 % of the kelts made it to the Baltic Sea. In 2009, a guidance rack was installed at upper Finsjö, and preliminary data show that fish bypass the turbines. Effects of different remedial measures are explored using a population model.