Summer habitat use and feeding of juvenile Arctic charr, Salvelinus alpinus, in the Canadian High Arctic

Abstract

– Owing to limited knowledge of the habitat use and diet of juvenile Arctic charr from the High Arctic, particularly young‐of‐the‐year (YOY), we assembled data obtained from samples taken in and around Lake Hazen, Nunavut, Canada, to assess juvenile habitat use and feeding. Juvenile charr demonstrated a preference for stream environments, particularly those fed by warm upstream ponds. Charr occupying both stream and nearshore lake habitats were found to feed similarly, with chironomids occurring most frequently in diets. Some older stream‐dwelling charr preyed on smaller, younger Arctic charr. Preferred stream occupancy is likely mediated by physical barriers created mainly by water velocity, and by distance from the lake, lake‐ice dynamics, low water depth, and turbidity. Water velocities resulted in stream habitat segregation by size, with YOY mainly found in low‐velocity pools and back eddies adjacent to stream banks, but not in water velocities >0.1 m·s−1. Greatest charr densities in streams were found in small, shallow, slow‐flowing side channels, which are highly susceptible to drought. Under predicted climate change scenarios, streams fed by small ponds will be susceptible to intermittent flow conditions, which could result in increased competition among juvenile charr for the remaining stream habitats. In addition, glacier‐fed streams are likely to experience increased flow conditions that will exacerbate physical barriers created by water velocity and further reduce the availability of preferred stream habitat.

Food resource partitioning between stream-dwelling Arctic charr Salvelinus alpinus (L.), Atlantic salmon Salmo salar L. and alpine bullhead Cottus poecilopus Heckel, 1836: an example of water column segregation

“…The present study exemplifies how the differences in the use of surface prey (terrestrial prey and emerged aquatic insects) among sympatric species can constitute an important adaptive feature to reduce interspecific competition in riverine fish communities during the summer. Thus, our findings suggest that Studies describing the trophic ecology of Arctic charr in running waters are scarce (but see Moore & Moore, 1974;Stenzel, 1987;Sinnatamby et al, 2012;Sánchez-Hernández et al, 2016). Moore & Moore (1974) observed that small Arctic charr (\100 mm) fed mostly on Chironomidae larvae.…”

“…Likewise, Stenzel (1987) found that the diet of juvenile Arctic charr is mainly composed of chironomids and other dipteran larvae. Recently, Sinnatamby et al (2012) confirmed Data are displayed for each month. The overlap/similarity is considered high when the index value exceeds 60% (values in bold)…”

“…There are numerous reports on trophic aspects of lacustrine Arctic charr populations (e.g. Langeland et al, 1991;Cavalli et al, 1998;Eloranta et al, 2015), but we know little about their feeding in running waters, although the few available studies suggest that the diet of riverine Arctic charr mainly is composed of Chironomidae larvae (Moore & Moore, 1974;Stenzel, 1987;Sinnatamby et al, 2012). Laboratory studies show that Arctic charr can feed in the water column, even though they may take a substantial proportion of their food from the bottom (Jørgensen & Jobling, 1990;Brännäs & Alanärä, 1992).…”

Anadromous char as an alternate food choice to marine animals: A synthesis of Hg concentrations, population features and other influencing factors

“…Several char studies have been conducted in northern Ellesmere Island in Quttinirpaaq National Park and at Alert (a military, meteorological and scientific research station) where there are many charcontaining lake and river systems, Lake Hazen being the most wellknown (Babaluk et al, 1997;Babaluk et al, 2007a;Babaluk et al, 2007b;Babaluk et al, 2009;Gantner et al, 2010b;Guiguer et al, 2002;Sinnatamby et al, 2012). Most char are landlocked, although Heintzelman Lake (13.5 km 2 ; maximum depth 15 m), with a close connection to the sea, has anadromous and resident char van der Velden et al, 2012).…”

From autochthonous to allochthonous resources: seasonal shifts in food use by stream‐dwellingYOYArctic charrSalvelinus alpinusthrough the ice‐free season

“…Few studies have addressed the feeding behaviour of stream‐dwelling S . alpinus , but the available studies highlight that juveniles predominantly feed on Chironomidae larvae and other aquatic dipterans during summer (Moore & Moore, ; Stenzel, ; Sinnatamby et al , ). This study addresses seasonal shifts in the feeding behaviour of YOY S .…”