Silver Eel Migration and Behaviour

Bruijs, Maarten C. M.; Durif, Caroline

doi:10.1007/978-1-4020-9095-0_4

Cited by 68 publications

(91 citation statements)

References 29 publications

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“…Various environmental factors have been proposed as triggering factors of the downstream migration of silver eels (Bruijs and Durif, 2009): turbidity (Verbiest et al, 2012), wind direction (Cullen and McCarthy, 2003), pH , conductivity (Durif, 2003;Verbiest et al, 2012), rainfall (Durif, 2003;Trancart et al, 2013), temperature (Vøllestad et al, 1986;Reckordt et al, 2014), atmospheric pressure (Acou et al, 2008), moon phase (Poole et al, 1990;Cullen and . Fig.…”

Section: Discussionmentioning

confidence: 99%

“…The pattern of sex-ratio between the downstream (male biased) and upstream (more or exclusively females) area of a river catchment (Oliveira and McCleave, 2000;Tesch, 2003;Drouineau et al, 2014) combined with the impact of obstacles may also lead to arrival mismatch between males and females or to gender disparities in terms of escapement success. Increased energy costs and injuries caused by passing through downstream obstacles may also impair escapement success for silver eels, which stop feeding during reproduction migration (Bruijs and Durif, 2009). In our study, a preliminary statistical analysis do not demonstrate any effect of fish length on escapement success, consequently, we did not include fish length in our model.…”

Section: Discussionmentioning

confidence: 99%

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Silver eel downstream migration in fragmented rivers: use of a Bayesian model to track movements triggering and duration★

Drouineau¹,

Bau²,

Alric³

et al. 2017

Aquat. Living Resour.

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-Obstacles in rivers are considered to be one of the main threats to diadromous fish. As a result of the recent collapse of the European eel, the European Commission introduced a Regulation, requiring to reduce all sources of anthropogenic mortality, including those caused by passing through hydropower turbines. Improving knowledge about migration triggers and processes is crucial to assess and mitigate the impact of obstacles. In our study, we tracked 97 tagged silver eels in a fragmented river situated in the Western France (the River Dronne). Using the movement ecology framework, and implementing a Bayesian state-space model, we confirmed the influence of river discharge on migration triggering and the distance travelled by fish. We also demonstrated that, in our studied area, there is a small window of opportunity for migration. Moreover, we found that obstacles have a significant impact on distance travelled. Combined with the small window, this suggests that assessment of obstacles impact on downstream migration should not be limited to quantifying mortality at hydroelectric facilities, but should also consider the delay induced by obstacles, and its effects on escapement. The study also suggests that temporary turbines shutdown may mitigate the impacts of hydropower facilities in rivers with migration process similar to those observed here.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Silver eel downstream migration in fragmented rivers: use of a Bayesian model to track movements triggering and duration★

Drouineau¹,

Bau²,

Alric³

et al. 2017

Aquat. Living Resour.

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“…After living in rivers and lakes for 8-18 years they migrate downstream to begin their 6000 km journey to the Sargasso Sea where they spawn and die. The triggers for their spawning-migration as silver eels are not fully understood but appear to be influenced by declining day length (photoperiod), high rainfall and a complex effect of the lunar cycle (Bruijs and Durif 2009). (Table 1).…”

Section: Eel Beaver and Horse Ecologymentioning

confidence: 99%

Eels, Beavers, and Horses: Human Niche Construction in the European Late Upper Palaeolithic

Brown¹,

Basell²,

Farbstein

2017

Proc. Prehist. Soc.

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“…A number of factors have been attributed to the decline, including variation in oceanic currents which reduce the rate of return (Baltazar-Soares et al 2014) and food availability (Friedland et al 2007) for leptocephali, and alter adult spawning location (Friedland et al 2007); over harvest (Moriarty and Dekker 1997); pollution (Knights 1997;Robinet and Feunteun 2002); parasitism (Feunteun 2002), and impeded migration between essential habitats (Bruijs and Durif 2009;Laffaille et al 2007;Winter et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Impact of Tide Gates on the Migration of Adult European Eels, Anguilla anguilla

Wright

Kemp

2015

Estuaries and Coasts

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Tide gates form a temporal barrier to fish migration, closing during the flood tide and opening during the ebb, primarily for flood prevention and land reclamation. Their impact on downstream adult migration of the critically endangered European eel, Anguilla anguilla, is unknown. The River Stiffkey, UK, has three top-hung tide gates (one counterbalanced, two not) through which it discharges into the North Sea. Adult eels of silver appearance (n = 118) were caught between 0.5 to 6.0 km upstream from the tide gates in Autumn 2011 and implanted with 23 mm half-duplex passive integrated transponder (PIT) tags. Tagged individuals were detected by PIT antennae located near the tide gates. Of the eels tagged, 80 were detected actively migrating downstream to the gates.Escapement past the gates was 98.3%. Speed of migration was slower near the gates than for an unimpeded upstream reach, and was positively and negatively related to mean degree of gate opening and mean light intensity, respectively. When the largest gate was modified through installation of an orifice intended to improve upstream passage of sea trout and juvenile eels, downstream migration was more rapid when it was operating. However, video analysis revealed that eels did not pass through the orifice, meaning that faster migration may have been a result of the gates being open on more occasions when eels initially approached them, or the lower tides and upstream saline intrusion that occurred during these periods. Top-hung tide gates in the River Stiffkey delayed eel migration, potentially increasing the risk of predation and energy expenditure immediately prior to a 5000 -6000 km migration to spawning grounds in the Sargasso Sea.

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Silver Eel Migration and Behaviour

Cited by 68 publications

References 29 publications

Silver eel downstream migration in fragmented rivers: use of a Bayesian model to track movements triggering and duration★

Silver eel downstream migration in fragmented rivers: use of a Bayesian model to track movements triggering and duration★

Eels, Beavers, and Horses: Human Niche Construction in the European Late Upper Palaeolithic

Impact of Tide Gates on the Migration of Adult European Eels, Anguilla anguilla

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