Improving the entrance of wild fish into pipe fishways

Freshwater fish populations have declined due to barriers obstructing movement and migration. Fishways can partially remediate these effects, including emerging technologies like pipe fishways. To inform effective pipe fishway design, the drivers of volitional fish entry were investigated under field conditions in New South Wales, Australia. Systematic experiments evaluated whether fish entrance to a pipe was impacted by using cone traps, attraction flow velocities, and light conditions. During trials, 1090 fish (20–120 mm total length) from six native species entered a 225 mm diameter pipe, with an average entrance proportion of 60% ± 25%. Using a cone trap increased fish counts by 200%, while attraction flow and natural light caused 49% and 44% increases, respectively. A secondary study indicated artificial light improved fish entrance counts. Natural light was the only variable that reduced the time taken for a fish to enter the pipe. Effective pipe fishway designs should consider employing a cone trap, an attraction flow, and natural light conditions to improve fish entry.