Author(s): Jeffrey A. Tuhtan; Juan Franciso Fuentes-Perez; Thomas Angerer; Martin Schletterer
Linked Author(s):
Keywords: No Keywords
Abstract: Upstream fish passage around instream barriers is typically facilitated by the installation of fishway structures. However, at some locations it is necessary to install fish lifts, which directly transport the fish vertically over and around the barrier. In this work, we report biological observations from the fish lift Runserau on the River Inn in Austria. Fish passing through a 600 m long upstream bypass pipe (DN400, inner diameter=37 cm) were transported from the fish lift exit upstream and away from the barrage, sustaining a drop from the bypass outfall of 5 m into the receiving water. In addition, drop heights of 1 and 2 m were investigated using live fish. The objectives of the study were two-fold: 1) To establish whether adult trout (Oncorrhynchus mykiss, n=55,280–450 g) experience injury or increased mortality after travelling through the pipe and sustaining a 1 to 5 m drop into the receiving water, and 2) to quantify and compare the pressure time series of external archival tags (25 g) on live fish with neutrally buoyant pressure sensors of identical make installed in a passive sensor array (143 g). The results indicate that the bypass system facilitates the injury-free upstream transport of fish, as it did not lead to any significant injury or mortality for all drop heights investigated. Furthermore, it was observed that the sensors installed on live fish exhibited pressure signals similar to the passive sensors. Together, these preliminary results provide promising experimental evidence that passive sensors can in some cases be applied as “electronic fish surrogates” in lieu of using live fish.
Year: 2018