Modify dams or water impoundments to enable wildlife movements
Overall effectiveness category Awaiting assessment
Number of studies: 1
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.
See also: Maintain dams or water impoundments.
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