Modify dams or water impoundments to enable wildlife movements

Overall effectiveness category Awaiting assessment
Number of studies: 1
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Background information and definitions

Dams or ‘impoundments’ may restrict aquatic reptile movements. Modifying dam structures, for example by providing ladders, may enable reptiles to move up and down stream of dam sites.

Study locations

Key messages

One study evaluated the effects on reptile populations of modifying dams or water impoundments to enable wildlife movements. This study was in the USA.

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (0 STUDIES)

BEHAVIOUR (1 STUDY)

Use (1 study): One study in the USA found that an eel ladder was used by common watersnakes in five of eight years.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

A study in 2007–2014 on a river in West Virginia, USA (Welsh & Loughman 2015) found that an eel ladder was used by common watersnakes Nerodia sipedon in five of eight years of monitoring. The ladder was used by common watersnakes (1–5 individuals/year) in five of eight years that the ladder was monitored. A stainless steel fish ladder (11 m long, 13 cm deep and 41 cm wide with a 50° slope containing a suitable substrate for climbing, see original paper for details), designed to facilitate the upstream passage of the snake-like movements of American eels Anguilla rostrata, was installed from late spring (May–July) to autumn (October–November) in 2007–2014 (106–188 days/year). Numbers of snakes (and eels) were monitored by live catching or photographs when they reached the upstream end of the ladder.
Study and other actions tested
Referenced paper
Welsh S.A. & Loughman Z.J. (2015) Upstream dam passage and use of an eel ladder by the common watersnake (Nerodia sipedon). Herpetological Review, 46, 176-179.

Please cite as:

Sainsbury K.A., Morgan W.H., Watson M., Rotem G., Bouskila A., Smith R.K. & Sutherland W.J. (2021) Reptile Conservation: Global Evidence for the Effects of Interventions for reptiles. Conservation Evidence Series Synopsis. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

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This Action forms part of the Action Synopsis:

Reptile Conservation

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Regulate water levels Action Link	Awaiting assessment	1	Synopsis Link
Maintain dams or water impoundments Action Link	Awaiting assessment	1	Synopsis Link