The biology and ecology of anadromous brown trout (Salmo trutta) and Arctic charr (Salvelinus alpinus) at sea is poorly understood. This study provided information on spatial and temporal distribution of sea trout and Arctic charr in a fjordsystem in Northern Norway. The behaviour of brown trout and Arctic charr veterans and brown trout post-smolts wwere tracked by using acoustic telemetry in a fjord system during 2015–2017.