Summer stream habitat preferences of Nunavik anadromous Arctic char (Salvelinus alpinus) fry and parr

Abstract

Arctic char is a fish species known to occupy diverse habitats within the Arctic region. However, summer habitat use during the juvenile stage of the anadromous form is largely unknown. The present study aims to characterize fry and parr summer habitat preferences. Surveys were conducted by electrofishing, associated with physical habitat characterization on several rivers of the Ungava Bay, Nunavik, Canada. At the microhabitat and station scales, fry showed significant habitat preferences for shallow water and slow velocity. At the mesohabitat scale, fry showed a significant habitat selectivity for riffles. This habitat selectivity implies that habitat models can be built to evaluate the potential of habitat suitability for Arctic char fry. However, no significant habitat selectivity was found for parr. Parr size was nonetheless positively correlated with velocity, which was found to be a limitative factor for juvenile habitat use. This first attempt at modeling juvenile anadromous Arctic char habitat in rivers emphasizes the importance of selecting an appropriate spatial scale and reiterates the fact that parr showed relatively high plasticity in stream habitat selection.

Population genomics, life‐history tactics, and mixed‐stock subsistence fisheries in the northernmost American Atlantic salmon populations

“…However, the magnitude of this effect is not clear for FEU, BAL, and GEO rivers, where the proportion or occurrence of estuarine salmon is unknown. In any case, the presence of Arctic char in FEU and GEO rivers (Dallaire et al., 2021; Dubos et al., 2022) (unknown in BAL R.), while absent from the Koksoak (Robitaille et al., 1986), may limit the occurrence of estuarine salmon. Second, despite the limited availability of environmental data, the northerly location of the FEU R. and the presence of the Torngats Mountains in the GEO R. watershed result in more arctic habitats compared to Koksoak and BAL rivers (MFFP, 2018).…”

“…However, the magnitude of this effect is not clear for FEU, BAL, and GEO rivers, where the proportion or occurrence of estuarine salmon is unknown. In any case, the presence of Arctic char in FEU and GEO rivers (Dallaire et al, 2021;Dubos et al, 2022) (unknown in BAL R.), while absent from the Koksoak (Robitaille et al, 1986), may limit the occurrence of estuarine salmon.…”

Nunavik anadromous Arctic char life histories, behaviour, and habitat use informed by both Inuit knowledge and western science: a year in Ungava Bay

“…Fry remain near the redds in calm bays along fast flowing rivers with a significant mean slope like for example Kuugat (Buet) and Avaluk (Vachon) rivers which have slope of 4.2 ‰ and 3.6 ‰ respectively for the first 30 km. Nonetheless, it has been shown from electrofishing data from Kangiqsualujjuaq and Tasiujaq that fry have a preference for riffle type habitat (Dubos et al 2022). Hence, the availability of this habitat type seems more limitative in Kangirsuk than near the other two communities where juveniles have access to various habitats and are able to show some site selectivity.…”

“…The juveniles of one year and more, called parr, are extensively using river mouths as summer habitat. Few of them were sampled using electrofishing in streams where fry were found in greater abundance (Dubos et al 2022), suggesting the use of different habitat types, potentially including river mouths and estuaries. According to the size of the smallest parr observed in river mouths by participants (±100-120 mm), they are likely to be one year old (Mainguy and Beaupré 2019a).…”