Keeping close to the river, shore and surface: the first marine migration of brown trout ( <scp> <i>Salmo trutta</i> </scp> ) and Arctic charr ( <scp> <i>Salvelinus alpinus</i> </scp> ) post‐smolts

Acoustic telemetry was utilized to track 49 brown trout (Salmo trutta) and 37 Arctic charr (Salvelinus alpinus) first-time migrants of wild origin [post-smolts; mean LF (fork length): 169 172 mm] in a large fjord northern Norway. The S. trutta were registered at sea for more than twice the time alpinus (medians 54 22 days, respectively). Both species mostly detected near river mouths (>80% detections) almost exclusively spent their (>95%) within interior 18 km fjord. They surface oriented, with most detections <1 m depth deeper on average (median depths 0.7 0.5 m, This study concludes that post-smolts both stay closer larger veteran migrants. emphasizes importance upper water layers survival during first marine migration.