Optimisation of adjusted barrier management to improve glass eel migration at an estuarine barrier

Mouton, Ans; Huysecom, Stijn; Buysse, David; Stevens, Maarten; Neucker, Tom Van den; Coeck, Johan

doi:10.1007/s11852-012-0230-3

Cited by 8 publications

(8 citation statements)

References 25 publications

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“…It has been suggested that the current, low recruitment of juvenile European eel to their freshwater rearing grounds may act as a population bottleneck (e.g. Bult & Dekker, ; Laffaille, Caraguel & Legault, ; Mouton et al ., ). Before the population decline, optimizing upstream passage solutions was not as imperative as it is today, as early passage solutions succeeded in transporting enough eels (due to high densities) past the barriers to reach the carrying capacity of the inland waters upstream of the barrier, at least in south‐western Europe (Dekker, ).…”

Section: Introductionmentioning

confidence: 97%

Climbing the ladder: an evaluation of three different anguillid eel climbing substrata and placement of upstream passage solutions at migration barriers

Watz

Nilsson

Degerman

et al. 2019

Animal Conservation

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Conservation programmes for endangered, long-lived and migratory species often have to target multiple life stages. The bottlenecks associated with the survival of juvenile anguillid eels migrating into inland waters, the survival and growth of the freshwater life stage, as well as the recruitment and survival of silver eels, migrating back to the ocean to spawn, must be resolved. In this study, we focus on the efficiency of passage solutions for upstream-migrating juveniles. Such solutions can consist of inclined ramps lined with wetted climbing substrata. We evaluated different commonly used substrata in a controlled experiment, recorded eel behaviour at the entrance of the ramp with infrared videography and validated the experimental results at a hydropower dam, where we also investigated the effects of ramp placement on performance. In the experiment on eel substratum selection, 40% of the eels passed in lanes with studded substratum, whereas only 21 and 5% passed using open weave and bristle substrata respectively. Video analysis revealed that the studded substratum attracted more approaches and initiated climbs than the other substrata, but once a climb had been initiated, passage success rates did not differ between substrata. Eels using the studded substratum climbed 26% faster than those using the bristle substratum and almost four times as fast as those climbing in the open weave. The superior performance of the studded substratum was supported by data from the field validation. Moreover, ramps positioned by the bank with low water velocities caught the most eels, but proximity to the dam had no effect on performance. To strengthen the European eel population, more juveniles need to reach their freshwater feeding grounds. A critical step to achieve this increase is to equip upstream passage solutions with suitable substrata and to optimize ramp placement at migration obstacles.

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Section: Introductionmentioning

confidence: 97%

Climbing the ladder: an evaluation of three different anguillid eel climbing substrata and placement of upstream passage solutions at migration barriers

Watz

Nilsson

Degerman

et al. 2019

Animal Conservation

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“…Crump weirs, common barriers to fish migration in the UK (Lucas & Frear 1997;Lucas & Bubb 2005;Russon et al 2010), are used to gauge river discharge as part of flood monitoring, and so retrofitting through installation of fish passes (Rhodes & Servais 2008) is preferred over their removal. Restricted upstream migration of this life stage represents a bottleneck for recruitment, alleviation of which is considered a principal target for conservation efforts (Mouton et al 2014). Restricted upstream migration of this life stage represents a bottleneck for recruitment, alleviation of which is considered a principal target for conservation efforts (Mouton et al 2014).…”

Section: Introductionmentioning

confidence: 99%

“…This study used glass eels as they represent the earliest developmental stage expected to utilise eel passes, and have been observed congregating below anthropogenic barriers (Feunteun et al 1998). Restricted upstream migration of this life stage represents a bottleneck for recruitment, alleviation of which is considered a principal target for conservation efforts (Mouton et al 2014). The first objective of this study was to quantify and compare upstream passage efficiency for an unmodified (no studded eel tiles on the downstream face; control) and modified (with eel tiles on the downstream face; treatment) model Crump weir.…”

Section: Introductionmentioning

confidence: 99%

Efficiency of a dual density studded fish pass designed to mitigate for impeded upstream passage of juvenile European eels (Anguilla anguilla) at a model Crump weir

Vowles

Don

Karageorgopoulos

et al. 2015

Fisheries Management Eco

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This study demonstrated that juvenile (glass) eels used a specific substrate (eel tiles) to circumvent a model Crump weir under an experimental setting. Upstream passage efficiency was 0 and 67% for the unmodified (no studded eel tiles on the downstream face; control) and modified (with studded eel tiles on the downstream face; treatment) set‐ups, respectively, and was greater for a small (59%) compared to large (41%) stud configuration. Eels were active and motivated to ascend the weir during both control and treatment set‐ups. Approach and attempt rates were elevated during the first few minutes of the treatment compared to control trials. Eels were edge‐oriented under both set‐ups and ascended the weir through the tiles during single burst swimming events (reaching estimated speeds of 68.5 cm·s−1). Eel tiles may provide a cost‐effective solution for mitigating impacts of anthropogenic barriers to juvenile eel migration. Further research is required to determine passage efficiencies under higher flows, for a greater size range of eel, and for other migratory anguilliform fish (e.g. lamprey, Lampretra spp. and Petromyzon marinus L.). The performance of eel tiles should be validated through robust field studies.

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“…Consequently, there is a need to investigate how management of protection structures can be optimised in order to minimise environmental and ecological impacts, whilst also maintaining out-of-stream objectives (e.g. Mouton et al, 2014). Short-term trials are valuable for providing an insight into the potential outcomes, and can be useful for building support with stakeholders, but ultimately there is a need for longer term studies to better understand the best ways to mitigate the effects of instream barriers on aquatic communities and habitats.…”

Section: Discussionmentioning

confidence: 99%

“…A number of studies have illustrated the benefits of adapted tide gate management for enhancing fish passage. For example, Mouton et al (2014) showed that glass eel (Anguilla anguilla) migration was improved at an estuarine barrier as a consequence of increased barrier opening during tidal rise and Boys et al (2012) observed improvement in both fish and crustacean communities following floodgate remediation. However, there has been little consideration given to mitigating the impact of tide gates on instream habitat.…”

Section: Introductionmentioning

confidence: 99%

Modified tide gate management for enhancing instream habitat for native fish upstream of the saline limit

Franklin

Hodges

2015

Ecological Engineering

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Optimisation of adjusted barrier management to improve glass eel migration at an estuarine barrier

Cited by 8 publications

References 25 publications

Climbing the ladder: an evaluation of three different anguillid eel climbing substrata and placement of upstream passage solutions at migration barriers

Climbing the ladder: an evaluation of three different anguillid eel climbing substrata and placement of upstream passage solutions at migration barriers

Efficiency of a dual density studded fish pass designed to mitigate for impeded upstream passage of juvenile European eels (Anguilla anguilla) at a model Crump weir

Modified tide gate management for enhancing instream habitat for native fish upstream of the saline limit

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