Hydroelectricity and fish: a synopsis of comprehensive studies of upstream and downstream passage of anadromous wild Atlantic salmon, Salmo salar, on the Exploits River, Canada

Abstract

Government (Fisheries and Oceans Canada) and industry (Abitibi Consolidated Company of Canada) have been working cooperatively to protect and enhance wild Atlantic salmon populations on the Exploits River, insular Newfoundland, Canada. Since the mid-1960s, enhancement programmes and construction of fish passage facilities at natural and man-made barriers in the watershed have expanded the range and increased the returning adult population from 1200 fish (circa 1960) to 22,000 fish, on average. Since 1997, attention has been paid to improving passage and survival of downstream migrating smolts and kelts at two hydroelectric facilities at Grand FallsWindsor and Bishops Falls. At Grand Falls-Windsor a floating louver and bypass system was installed in a power canal and extensive biological, hydraulic, and modelling studies have been conducted to assess, modify, and optimize fish passage. At Bishops Falls, a retrofitted surface spill bypass system was installed in an existing spill gate and similar studies have been conducted to improve passage success. Studies have also been conducted on the upstream migrating adults at these facilities and associated fishways, using conventional and physiological telemetry, to assess tailrace attraction and residency, and the relative energy cost of upstream migration to bypass the hydro plants and fishways. This article reviews the results of these various studies to demonstrate how cooperative work has improved passage of anadromous salmon in coexistence with hydroelectric development.

A concept for improving Atlantic salmon Salmo salar smolt migration past hydro power intakes

“…It has been suggested that the use of screening systems (Scruton et al , 2008) and strobe lights (Johnson et al , 2005) can guide or scare fishes away from intakes. Thus, in 2008 a floating boom was introduced in front of the intake tunnel and one submerged strobe light on each side of the tunnel entrance, both facing upstream towards a point in the middle of the intake flow.…”

“…Re‐establishment of migration routes is essential to re‐introduce or enhance these populations across their distribution areas. While research and implementation of upstream migration solutions is extensive, and indeed often successful (Scruton et al , 2008), seaward migration of juveniles (smolts) remains a major challenge in many river systems. Salmonid smolts are small and numerous, and they appear to follow the main discharge (Rivinoja, 2005) often leading them into the hydropower intake and turbines.…”

“…Prediction of timing of the smolt run is a crucial foundation for the planning of fish‐friendly power production. Subsequently, successful diversion of smolts into bypass systems often relies on diverting large parts of the river discharge into the bypass, at the cost of power production, or large scale and often expensive screening systems (Johnson & Dauble, 2006; Scruton et al , 2008). The latter may be challenging in systems with organic debris or where power intakes and bypass systems are not within immediate proximity, and in particular, retrofitting existing installations with bypass systems is a challenge.…”

Turbine entrainment and passage of potadromous fish through hydropower dams: Developing conceptual frameworks and metrics for moving beyond turbine passage mortality

“…Once dispersers enter the forebay, downstream passage efficiency will then be determined by the ability to locate and enter turbine entrances, which can be estimated using FEZ Entry p . We are beginning to learn more about the forebay and reservoir hydraulic conditions that promote guidance for out‐migrating anadromous species (Enders, Gessel, & Williams, ; Kemp, Gessel, & Williams, ; Scruton, McKinley, Kouwen, Eddy, & Booth, ; Scruton et al., ). In general, increased velocities tend to promote guidance for anadromous salmonids.…”

Economic and policy considerations regarding hydropower and migratory fish

“…Additionally, due to disregard of environmental consequences, partly due to unawareness, river habitats have been seriously degraded by alterations to water clarity and temperature as well as species abundance and diversity (Schilt ; Scruton et al . ).…”