Distinct freshwater migratory pathways in Arctic char (Salvelinus alpinus) coincide with separate patterns of marine spatial habitat-use across a large coastal landscape

Abstract

Understanding variability in distributions and habitat-use among populations of anadromous salmonids is essential for their sustainable management. Arctic char ( Salvelinus alpinus) is an important cultural and socioeconomic species; however, knowledge of their spatiotemporal habitat-use during the marine phase is limited. Here, a large-scale acoustic telemetry array was used to determine intraspecific variation in Arctic char summer marine habitat-use tied to overwintering lake occurrence in the Amundsen Gulf. Arctic char tagged in the ocean migrated to two main overwintering lakes, corresponding to distinct migration corridors and separate patterns of marine habitat-use, with one individual exhibiting among the longest recorded char marine migration to date (∼330 km). Arctic char that undertook longer migration distances initiated travel in the ocean towards fresh water 11 days earlier than those completing shorter migration distances; mean departure days (±SD) 2 August (±8.1 days) and 13 August (±6.8 days), corresponding to migration distances of 252 and 131 km, respectively. These findings identify that Arctic char from different populations can occupy distinct marine foraging grounds within a region, with consequences for variable interactions with fisheries.