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Providing evidence to improve practice

Action: Procambarus crayfish control: Create barriers Control of Freshwater Invasive Species

Key messages

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  • A before-and-after study conducted between 2007 and 2010 in Spain found that the use of concrete dams across a stream, specifically designed with features to prevent red swamp crayfish from crawling over them, were effective at containing spread of the population upstream.


Supporting evidence from individual studies


A before-and-after study from 2007 to 2010 in a mountain stream in Italy (Dana et al. 2011) found that building a series of small dams stopped migration of the red swamp crayfish Procambarus clarkii. The invasive crayfish did not penetrate into previously uninhabited areas upstream beyond the lower dams. In addition, numbers dropped below detectable levels in previously occupied areas in the mid reaches between dams. Dams were 1.5–2 m high and 6 m wide and constructed from reinforced concrete. Several design features discouraged crayfish from climbing over including vertical walls, smooth mortar, vertical wing-walls 3.5 m along the banks, and a projecting rim (crayfish are unable to walk upside down on a smooth surface). A flat stony platform was built downstream of each dam to create a shallow area with no refuges, discouraging crayfish from lingering near the dam. Crayfish populations were monitored for 30 days between July and October each year.


Referenced papers

Please cite as:

Aldridge, D., Ockendon, N., Rocha, R., Smith, R.K. & Sutherland, W.J. (2019) Some aspects of control of freshwater invasive species. Pages 569-602 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2019. Open Book Publishers, Cambridge, UK.