Suitability of Vertical Slot and Denil Fishways for Passing North-Temperate, Nonsalmonid Fish

Abstract

A vertical slot fishway and two Denil fishways (of 10 and 20% slope) built into a weir on the Lesser Slave River (55°18′N, 115°45′W) were studied from May 12 to June 25, 1984, to determine how effectively these designs pass north-temperate, nonsalmonid fishes. Thousands of spottail shiner (Notropis hudsonius), substantial numbers (> 100) of northern pike (Esox lucius), longnose sucker (Catostomus catostomus), white sucker (Catostomus commersoni), immature yellow perch (Perca flavescens), and lesser numbers of burbot (Lota lota), adult yellow perch, lake whitefish (Coregonus clupeaformis), and trout-perch (Percopsis omiscomaycus) ascended the fishways. Walleye (Stizostedion vitreum) and goldeye (Hiodon alosoides), although probably moving extensively through the river, did not use the fishways. Although high water levels allowed most fish to surmount the weir, of those that chose the fishway, pike strongly preferred to ascend the Denil fishways and the two sucker species preferred to ascend the vertical slot. Therefore, a combination of several different fishways may be required for the most efficient passage of a wide variety of species. Plasma glucose and lactate measurements on pike revealed that ascending the Denil fishways was only moderately stressful for these fish.