Efficiency of a fish lift for returning Atlantic salmon at a large‐scale hydroelectric complex in France

Abstract

This study describes the behaviour of radio-tagged returning Atlantic salmon, Salmo salar L., at the Golfech-Malause hydroelectric complex on the River Garonne, France. The particularity of this complex is that it is fitted with a fish lift, a type of fishway rarely tested for salmon. Only forty seven percent of salmon succeeded in passing. Frequenting of both the tailrace and the foot of the plant, where the lift was located, decreased rapidly during the blockage. Successful salmon spent proportionally more time near the entrance of the lift. The high mean number of visits to the lift entrance before upstream passage (51) suggested the lift was not sufficiently attractive. Evidence is also given of the difficulties specific to fish lifts that involve trapping fish: the V-shaped entrance of the fish lift holding pool could inhibit salmon without even guaranteeing a non-return effect.

Upstream Movements of Atlantic Salmon in the Lower Penobscot River, Maine Following Two Dam Removals and Fish Passage Modifications

“…When fish do enter the fishway, another potential influential factor is suboptimal operation of the V-shaped gate at the hopper entrance. Previous studies have documented low probabilities of passing through V-shaped entrances to lift holding pools for Atlantic Salmon (0.15 in Larinier et al 2005;0.17 in Croze et al 2008) and have additionally documented that up to 40% of entries through a V-shaped gate can result in salmon returning to the area outside of the fish lift (Croze et al 2008). Both hesitation to both enter and frequently return back through the V-shaped gate could be contributing to the delays observed at the Milford Dam fish lift.…”

“…Reported passage efficiencies range from 47% (Croze et al 2008) to 87% (Larinier et al 2005) at lifts located on European rivers. In the study conducted by Croze et al (2008) on the River Garonne, France, mean delay time at the fish lift was 12.5 ATLANTIC SALMON MOVEMENTS IN PENOBSCOT RIVER d. On the Gave de Pau River, France, a median delay time of 9 d was reported at the Baigts hydroelectric plant (Larinier et al 2005). While delay times differed across systems, behavior of tagged salmon in our study was similar to the behavior of Atlantic Salmon at the fish lifts in Europe.…”

“…While delay times differed across systems, behavior of tagged salmon in our study was similar to the behavior of Atlantic Salmon at the fish lifts in Europe. Authors reported tagged fish rapidly approaching the entrance to the fish lift after arriving at the dam (74% in less than 24 h [Larinier et al 2005]; 79% within 1 h [Croze et al 2008]) and then making multiple visits to the entrance before successfully being trapped and lifted. In the second year of our study, tagged salmon located the fishway rapidly but made multiple visits, often over many days (or weeks), before successful passage.…”

Species and river specific effects of river fragmentation on European anadromous fish species

“…Higher mortality is caused by enhanced predation in impoundments and by hydropower turbine passage during downstream migration (Brevé et al, ; Calles, Rivinoja, & Greenberg, ; Jepsen et al, ; Wilkes, Mckenzie, & Webb, ). In addition, it takes time to pass through a fish passage (Baisez et al, ; Croze, Bau, & Delmouly, ). As such, fish passages need to be designed in such a way that they ensure minimal passage delay and have little to no postpassage impacts (Silva et al, ).…”

Economic and policy considerations regarding hydropower and migratory fish

“…In Garonne River, France, the entrance of a fish lift was found to function poorly in attracting Atlantic salmon, with only 47% ascension through it (Croze et al 2008). However, the lift was found to function well for some species of interest, such as Allis shad (see Marmulla 2001 and references therein).…”