Climate Impacts on Arctic Freshwater Ecosystems and Fisheries: Background, Rationale and Approach of the Arctic Climate Impact Assessment (ACIA), General Features of the Arctic Relevant to Climate Change in Freshwater Ecosystems, Historical Changes in Arctic Freshwater Ecosystems, Climate Change Effects on Hydroecology of Arctic Freshwater Ecosystems, Climate Change Effects on Aquatic Biota, Ecosystem Structure and Function, General Effects of Climate Change on Arctic Fishes and Fish Populations, An Overview of Effects of Climate Change on Selected Arctic Freshwater and Anadromous Fishes, Effects of Ultraviolet Radiation and Contaminant-Related Stressors on Arctic Freshwater Ecosystems, Effects of Climate Change and UV Radiation on Fisheries for Arctic Freshwater and Anadromous Species, Effects of Climate Change and UV Radiation on Fisheries for Arctic Freshwater and Anadromous Species, Key Findings, Science Gaps and Policy Recommendations.