Nonsalmonid versus Salmonid Passage at Nature‐Like and Pool‐and‐Weir Fishways in Atlantic Canada, with Special Attention to Rainbow Smelt

Abstract

AbstractIn recent years, fish passage efforts have begun shifting away from targeting salmonids and instead toward passing entire fish communities, including nonsalmonids. The objectives of this study were to evaluate the performance of a nature‐like fishway and a pool‐and‐weir fishway at passing Rainbow SmeltOsmerus mordax(2014 and 2016) and Brook TroutSalvelinus fontinalis(2015 and 2016). Both fishways are located at the same dam on the Glenfinnan River, Prince Edward Island, Canada. Fish werePIT‐tagged, and their movements were tracked using stationaryPITantennas. Results indicated that passage efficiency at the pool‐and‐weir fishway was 0% for Rainbow Smelt in both years. In contrast, 100% and 99.2% of Brook Trout passed the pool‐and‐weir fishway in 2015 and 2016, respectively. At the nature‐like fishway, the highest passage efficiency measured for Rainbow Smelt was 28.6% (2016) and was not significantly different between years. In comparison, 100% and 91.7% of Brook Trout passed the nature‐like fishway in 2015 and 2016, respectively. Additionally, attempts to improve attraction efficiency at the nature‐like fishway by directing more water toward the fishway's entrance and removing instream debris were made in 2015, but attraction efficiency did not differ between 2014 and 2016. Finally, Rainbow Smelt were also observed spawning throughout the nature‐like fishway. This study adds to the growing evidence that fishways designed specifically for salmonids can be inappropriate for nonsalmonids. Data indicate that although some passage of Rainbow Smelt was noted at the nature‐like fishway relative to the pool‐and‐weir fishway, overall passage was low. Future efforts directed at improving passage should focus on adjusting the entrance location of the nature‐like fishway. Despite low overall passage for Rainbow Smelt, the presence of spawning adults within the nature‐like fishway suggests that the fishway itself provides suitable spawning habitat and that fishway performance evaluation should take this into consideration.