Behaviour and Microhabitat of Young Atlantic Salmon (Salmo salar) during Winter

Abstract

Underwater observations at two sites along a small Nova Scotian river were carried out between December and April (water temperature range = 0.5–7.0 °C) to describe the winter microhabitat of young Atlantic salmon (Salmo salar). Salmon (5–15 cm fork length) were consistently found hiding beneath rocks (mean diameter = 16.8–23.0 cm) in riffle-run habitats where mean water depths were 40.9–48.9 cm and mean water velocities were 38.7–45.7 cm∙s−1. Many of the salmon were found overwintering within redd excavations. "Home stones" were distributed closer to midstream than to river banks and where sediment compaction was minimal. Monthly collections of fish (ages 1 and 2) indicated that feeding continued over winter. The data suggest a nocturnal activity pattern and photonegative response by young salmon during winter.

Estimating relative abundance of juvenile brown trout in rivers by underwater census and electrofishing

“…Other contributing factors include the difficulty of seeing fish in shallow river margins and amongst rocks, and possible double counting of highly mobile individuals. Substrate hiding behaviour has been widely reported for juvenile brown trout (Hartman 1963;Heggenes & Saltveit 1990;Heggenes et al 1993) and other salmonid species (Hartman 1965;Chapman & Bjornn 1969;Hillman & Griffith 1987;Cunjak 1988) and has been linked to a seasonally related temperature response.…”

Protecting sediment-sensitive aquatic species in mountain streams through the application of biologically based streambed sediment criteria

“…Steelhead, Atlantic salmon, chinook, cutthroat, brook trout and brown trout have all been shown to prefer stream substrates with interstitial voids (see review in Chapman and McLeod 1987). Age 0 Atlantic salmon and steelhead often seek refuge within the substrate especially during low winter stream temperatures (Hartman 1963(Hartman , 1965Everest 1969;Kelley and Dettman 1980;Rimmer et al 1981;Cunjak 1988). Experimentally induced reduction of interstitial voids with coarse sands in a natural stream has resulted in reduced juvenile salmonid densities (Alexander and Hansen 1983).…”

Note de synthèse sur la sélection de niche spatiale et la compétition chez le jeune saumon Atlantique (Salmo salar) et la truite commune (Salmo trutta) en milieu lotique

“…Most studies are done during daytime in summer and at low waterflows. However, temporally variable water flows and températures are pervasive environmental factors that affect behaviour and spatial niche sélection in salmon and trout and other streamfishes (CUNJAK, 1988 ;HEGGENES etal., 1993 ; FRASER e?a/.,1994).…”