Hydropower-related mortality and behaviour of Atlantic salmon smolts in the River Sieg, a German tributary to the Rhine

Havn, Torgeir Børresen; Thorstad, Eva B.; Teichert, Maxim; Sæther, Stig Arve; Heermann, Lisa; Hedger, Richard D.; Tambets, Meelis; Diserud, Ola Håvard; Borcherding, Jost; Økland, Finn

doi:10.1007/s10750-017-3311-3

Cited by 28 publications

(30 citation statements)

References 38 publications

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“…Nettles and Gloss (1987) reported that turbine entrainment of land-locked Atlantic salmon was reduced after the installation of an angled 25-mm trash rack on the Boquet River, but because of substantial losses recorded upstream of the plant, passage efficiencies were not reported. Havn et al (2018) reported a dam passage efficiency of 75-84% for Atlantic salmon smolts for a facility with inclined 10-mm racks and multiple bypass entrances on the River Sieg; the losses mainly occurred in the reservoir and inside the bypass facility, i.e. similar to our findings at Herting.…”

Section: Discussionsupporting

confidence: 88%

An angled rack with a bypass and a nature-like fishway pass Atlantic salmon smolts downstream at a hydropower dam

Nyqvist

Elghagen

Heiss

et al. 2018

Mar. Freshwater Res.

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Hydropower dams disrupt longitudinal connectivity and cause fragmentation of river systems, which has led to declines in migratory fish species. Atlantic salmon smolts rely on intact longitudinal connectivity to move downstream from rearing habitats in freshwater to feeding grounds at sea. Smolts often suffer increased mortality and delays when they encounter hydropower plants during their downstream migration. Currently, there are few examples of downstream passage solutions that allow safe and timely passage. We assessed the performance of two passage solutions at a hydropower dam, namely, an angled 15-mm rack with a bypass and a large nature-like fishway. The performance of these new fish passage solutions was evaluated by tracking radio-tagged Atlantic salmon smolts as they encountered the facilities. The radio-tagged smolts passed the dam 9.5h after release (median) and exhibited a dam-passage efficiency of 84%, with passage rates increasing with body length. Fish passage occurred through both the rack bypass and the nature-like fishway. The passage efficiencies were 70–95% for the rack bypass and 47% for the nature-like fisway. The new fish passage facilities resulted in improved passage conditions at the site, confirming that angled racks with bypasses as best-practise solutions for downstream passage, but also that large nature-like fishways may act as downstream passage routes for salmon.

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Section: Discussionsupporting

confidence: 88%

An angled rack with a bypass and a nature-like fishway pass Atlantic salmon smolts downstream at a hydropower dam

Nyqvist

Elghagen

Heiss

et al. 2018

Mar. Freshwater Res.

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“…The power station has three Francis turbines with a total capacity of 27 m 3 /s and exploits a drop of 2.7 m. Each of the three turbine intakes are covered by a horizontally sloped rack (27° relative to the ground) with 10 mm bar spacing. Ten migration routes can be used by downstream migrating fish past the power station (Figure S1, further details are given in Havn et al, ). Water discharge in the vertical slot fish passage was 0.3 m 3 /s, in the nature‐like fishway 0.2 m 3 /s and in the canoe pass 0.2 m 3 /s.…”

Section: Methodsmentioning

confidence: 99%

Mortality of downstream migrating European eel at power stations can be low when turbine mortality is eliminated by protection measures and safe bypass routes are available

Økland

Havn

Thorstad

et al. 2019

Internat Rev Hydrobiol

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The abundance of the European eel has seriously declined during recent decades. Hydropower production is one of the main threats, and solutions at power stations are needed to reduce the mortality of the downstream migrating silver eel. We examined the mortality, migration routes, and behavior of silver eel at a power station in Germany, after the power station was rebuilt to reduce the mortality of downstream migrating fish. Of 270 eels implanted with radio transmitters and released upstream of the power station, 222 eels passed the power station, primarily in October and November, although some descended during winter and spring. Most eels followed the main flow and passed over the spillway gate (59% and 49% in the 2 study years) or followed the route toward the bar racks in front of the turbines (24% and 27%), where they were guided to a route outside the turbines via the flushing channel. Some eels used the vertical slot fish passage (12% and 8%), whereas few used a nature‐like fishway, canoe pass, or custom‐made bypasses for eel. The eels showed large individual variation in migration timing, migration speeds, and choice of bypass. No eels were killed in the turbines, as none passed through them, likely due to the narrow bar spacing of the racks (10 mm). The results demonstrated that the mortality of eel passing power stations can be low (0–4% and 0–8% in the 2 study years) when the turbine intake is covered by racks hindering eels from entering turbines and safe bypass routes are available. Mortality estimates are given as ranges because the fate of 4% and 8% of the individuals could not be determined. Potential mortality could have been related to injuries in the bypass routes or increased predation risk, but there were no indications of injuries caused by installations in any of the bypass routes.

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“…Wenn es möglich ist, dass die Fische an dem Punkt des Suchverhaltens die Strömung zu einem Bypass wahrnehmen, besteht die Möglichkeit, dass die Fische, die eigentlich durch den Rechen geschwommen wären, in den Bypass schwimmen. Ein ausgeprägtes Suchverhalten an einer Wasserkraftanlage kann jedoch auch dazu führen, dass die Abwanderung der Fische verzögert wird . Eine solche Verzögerung der Abwanderung kann sich wiederum negativ auf den Abwanderungs‐ und Laicherfolg der Fische auswirken .…”

Section: Ergebnisse Und Interpretationunclassified

Einfluss geometrischer und hydraulischer Parameter auf das Verhalten abwandernder Fische an Wasserkraftanlagen

et al. 2018

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Für den Schutz abwandernder Fische vor einer schädlichen Turbinenpassage können Rechen‐Bypass‐Systeme eine wirksame Maßnahme sein. Um möglichst viele Fische auf ihrer abwärtsgerichteten Wanderung durch ein solches System zu schützen, sollten die Verhaltensweisen der Fische bei der Bemessung des Systems Berücksichtigung finden. In ethohydraulischen Untersuchungen mit Aalen, Äschen, Flussbarschen, Lachssmolts und Rotaugen wurden geometrische und hydraulische Parameter eines Vertikalrechens getestet, um über die Kombination aus Verhaltensbeobachtungen der Fische und Strömungsmessungen Erkenntnisse über die Wirkung des Rechens zu ermitteln. Die Ergebnisse der Auswertung der Verhaltensweisen zeigen, dass neben der Anströmgeschwindigkeit vor allem der Rechenstababstand einen maßgebenden Einfluss auf die Filterwirkung eines Rechens und das Suchverhalten der Fische hat.

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Hydropower-related mortality and behaviour of Atlantic salmon smolts in the River Sieg, a German tributary to the Rhine

Cited by 28 publications

References 38 publications

An angled rack with a bypass and a nature-like fishway pass Atlantic salmon smolts downstream at a hydropower dam

An angled rack with a bypass and a nature-like fishway pass Atlantic salmon smolts downstream at a hydropower dam

Mortality of downstream migrating European eel at power stations can be low when turbine mortality is eliminated by protection measures and safe bypass routes are available

Einfluss geometrischer und hydraulischer Parameter auf das Verhalten abwandernder Fische an Wasserkraftanlagen

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