Providing evidence to improve practice

Individual study: Biological control of invasive populations of crayfish: The European eel (Anguilla anguilla) as a predator of Procambarus clarkii.

Published source details

Aquiloni L, Brusconi S, Cecchinelli E, Tricarico E, Mazza G, Paglianti A & Gherardi F (2010) Biological control of invasive populations of crayfish: The European eel (Anguilla anguilla) as a predator of Procambarus clarkii. Biological Invasions, 12, 3817-3824


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Procambarus crayfish control: Encouraging predators Control of Freshwater Invasive Species

One replicated, controlled laboratory study conducted in 2006 on specimens from wetlands and irrigation ditches in Italy (Aquiloni et al. 2010) found that the eel Anguilla anguilla, preyed effectively on red swamp crayfish Procambarus clarkii compared with the control tank (no predator). Different sizes of crayfish were preyed upon at a similar rate (one crayfish every four days/eel).  The number of dead crayfish in tanks increased when the crayfish were moulting. Crayfish were weighed and measured and placed within four aerated plastic tanks (100 cm diameter, 30 cm depth). Three tanks held 10 hard-shelled, male crayfish of one size class and an eel. There were three size classes in total. One tank had 10 crayfish but no eel (control). Over 14 days, the number and weight of crayfish preyed upon were recorded. Dead crayfish were replaced with live individuals and experiments were replicated five times.

 

Procambarus crayfish control: Encouraging predators Control of Freshwater Invasive Species

A second replicated, controlled study conducted in 2007 in a canal in Italy (Aquiloni et al. 2010) found that the eel Anguilla anguilla, preyed effectively on red swamp crayfish Procambarus clarkii compared with the control tank (no predator). The eels predated more on smaller than on larger crayfish. Crayfish were measured and placed in cages (50 x 50 x 200 cm; 2 mm mesh width) that were 3 m apart from each other. Each cage held five hard-shelled, male crayfish of one size class. Three size classes were used in total. In half of the cages, an adult eel was placed. The other cages were controls (no eel). Over 20 days, once a week, number and size of dead crayfish was recorded.

 

Procambarus crayfish control: Trapping combined with encouragement of predators Control of Freshwater Invasive Species

A replicated, paired sites study conducted in 2008 in two artificial canals in Italy (Aquiloni et al. 2010) found that trapping was more effective than using a predator, the eel Anguilla anguilla, in controlling red swamp crayfish Procambarus clarkii populations. Transects containing low densities of eel did not effectively reduce red swamp crayfish Procambarus clarkii densities in comparison to transects containing traps. When trapping was suspended for a month, crayfish populations increased, indicating that trapping effectively reduces crayfish population sizes.  In each canal, two transects (150 x 3 m) were delimited using 2 mm-mesh wire netting. Crayfish density was estimated by trapping with 6 traps per transect for one week. After one week, 15 adult eels were put in one transect/canal. Trapping continued for two weeks. The sex and length of each trapped crayfish was determined. The number of live crayfish was monitored.