Latvia's longest river carves a scenic valley through Devonian red sandstone in Gauja National Park. In practical regulated-fishing terms, the strongest current public evidence is for licensed Salmo trutta fishing on the Gauja in designated Valmiera County sections rather than for a broad salmon-destination reading of the whole river. The sandstone geology gives the river a softer, less alkaline character than limestone waters. Atlantic salmon are managed under national and EU Baltic conservation rules, with quotas, size limits and seasonal restrictions; catch-and-release is widely applied — check current rules before fishing.

• Sandstone