Associations between iKaluk/Arctic charr (Salvelinus alpinus) and estuarine benthic diatom habitats in nearshore Nunatsiavut waters

Abstract iKaluk, Inuttitut for Arctic charr (Salvelinus alpinus), holds significant commercial and cultural value for Inuit communities throughout Nunatsiavut. Studies evaluating iKaluk habitat associations in freshwater are plentiful; however, there is limited information on the ecological makeup and sediment characteristics of anadromous charr habitats in marine environments. This study investigated the benthic associations of Arctic charr during their marine residency period in Nain, Nunatsiavut, using underwater videos, harvester-identified fishing locations, and acoustic telemetry. Drop-camera surveys were deployed on previously placed hydrophone acoustic receivers and within harvester-identified fishing locations to describe and quantify available benthic habitats in the study area. Telemetry information was used to identify charr occupancy hotspots, and calculate habitat suitability indices. A total of 248,056 benthic organisms belonging to 63 morphotaxa were identified within the 125 video drops used for benthic community characterization and these represented five faunal assemblages. Marine phase charr occupied estuaries to a greater degree than other fjord or coastal headland environments and these habitats were typically characterized by fine sediments covered by high densities of brittle stars (Ophiuroidea spp.) and benthic diatom mats. The consistent presence of diatomaceous sediments is indicative of abundant foraging opportunities. The importance of these habitats to iKaluk, need to be considered in future marine planning given the cultural and ecological value of this species to many northern communities that face growing threats from environmental change.