Size-mediated, density-dependent cannibalism in the signal crayfish Pacifastacus leniusculus (Dana, 1852) (Decapoda, Astacidea), an invasive crayfish in Britain

R. J. Houghton*, C. Wood, X. Lambin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)
10 Downloads (Pure)


The role of cannibalism in crayfish populations is not well understood, despite being a potentially key density-dependent process underpinning population dynamics. We studied the incidence of cannibalism in an introduced signal crayfish Pacifastacus leniusculus population in a Scottish lowland river in September 2014. Animals were sampled using six different sampling techniques simultaneously, revealing variable densities and size distributions across the site. Cannibalism prevalence was estimated by analysing the gut contents of crayfish <20 mm CL for the presence of crayfish fragments, which was found to be 20% of dissected individuals. When seeking evidence of relationships between the sizes of cannibals and ?prey', the density of conspecifics >56% the size of a dissected individual yielded the best fit. The relationship between cannibalism probability and crayfish size and density was equally well described by three different metrics of crayfish density. Cannibalism increased with crayfish size and density but did not vary according to sex. These results suggest that large P. leniusculus frequently cannibalize smaller (prey) conspecifics, and that the probability of cannibalism is dependent upon the relative size of cannibal-to-prey and the density of the smaller crayfish. We suggest that removing large individuals, as targeted by many traditional removal techniques, may lead to reduced cannibalism and therefore a compensatory increase in juvenile survival.

Original languageEnglish
Pages (from-to)417-435
Number of pages19
Issue number4
Publication statusPublished - 2017

Bibliographical note

Many thanks to the University of Aberdeen who funded the project and Robert Laughton, director of the Findhorn, Nairn and Lossie Fisheries Trust, who provided useful field work advice and equipment. Thank you to Scottish Natural Heritage for support and facilitating the project with swift licensing (licence no. 22482). We would also like to acknowledge the Peoples Trust for Endangered Species (PTES) for their sponsoring of Connor Wood and for their support of our research. Many thanks also to Ewan McHenry for his assistance with data collection in the field.


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