Effectiveness of Naturelike Fishway Designs for Passage of Anadromous and Riverine Species

Naturelike fishway designs have been proposed as a solution for passing a broad range of species.  A growing perception that technical fishways fail to pass a diversity of species has fueled enthusiasm for the naturelike approach.  This enthusiasm, however, has little foundation in evaluated structures.  We have conducted assessments of several designs of naturelike fishways with more than 4000 individual fish representing 23 riverine and diadromous species native to the Northeast.  We performed these studies both in the field and in a large-scale laboratory setting.  Results indicate that naturelike designs are not intrinsically superior to technical fishways: passage performance varied widely among species, designs, and hydraulic conditions.  Some designs in widespread use may actually be worse for some species than existing technical fishway designs.  However other designs show real promise, providing expeditious passage for nearly all species tested.