Efficiency of an estuarine fishway for the passage of salmon (Salmo salar L.), Sheet Harbour, Nova Scotia / Vivien M. Brawn (Srivastava).: Fs97-4/1523E-PDF

"An estuarine vertical-slot fishway, beside the powerhouse tailrace at East River, Sheet Harbour, Nova Scotia, was found to pass returning adult salmon most effectively at mid- and high tide and between 11:00 and 13:00, Atlantic Standard Time. A drop in salmon ascents at three-quarters tide, compared with those at mid-tide, was attributed to a decrease in velocity of the discharge and/or its greater height above the entrance floor. When the slot was partially blocked from above to create a submerged orifice entrance, the overall efficiency of the fishway was improved and three-quarter tide became the most favoured tide for ascent. The low efficiency at low and quarter tides was attributed to partial blockage of the entrance by exposed ledges and to low water levels over the entrance floor. In 1978, a second vertical-slot fishway was in operation at a barrier dam across the old riverbed at head of tide, 180 m (600 ft) upstream of the powerhouse tailrace. Passage of salmon up this fishway through the fall of 1978 was highly dependent on the presence of artificial freshets over the barrier dam. The ability to generate freshets at this site made the new fishway much more effective for the passage of salmon than the original fishway at the tailrace. The relative efficiency of the two fishways under spring conditions remains to be studied"--Abstract.

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