Propagule pressure and the invasion risks of non-native freshwater fishes: a case study in England

Authors

  • G. H. Copp,

    Corresponding author
    1. * Salmon & Freshwater Team, Centre for Environment, Fisheries & Aquaculture Science, Pakefield Road, Lowestoft, Suffolk, NR33 0HT, U.K., Rural Policy Directorate, Foss House, 1-2 Peaseholme Green, York, YO1 7PX, U.K. and § Centre for Ecology and Hydrology Dorset, Winfrith Technological Centre, Winfrith Newburg, Dorchester, DT2 8ZD, Dorset, U.K.
      †Tel.: +44 (0) 1502527751; fax: +44 (0) 1502513865; email: gordon.copp@cefas.co.uk
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  • M. Templeton,

    1. * Salmon & Freshwater Team, Centre for Environment, Fisheries & Aquaculture Science, Pakefield Road, Lowestoft, Suffolk, NR33 0HT, U.K., Rural Policy Directorate, Foss House, 1-2 Peaseholme Green, York, YO1 7PX, U.K. and § Centre for Ecology and Hydrology Dorset, Winfrith Technological Centre, Winfrith Newburg, Dorchester, DT2 8ZD, Dorset, U.K.
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  • R. E. Gozlan

    1. * Salmon & Freshwater Team, Centre for Environment, Fisheries & Aquaculture Science, Pakefield Road, Lowestoft, Suffolk, NR33 0HT, U.K., Rural Policy Directorate, Foss House, 1-2 Peaseholme Green, York, YO1 7PX, U.K. and § Centre for Ecology and Hydrology Dorset, Winfrith Technological Centre, Winfrith Newburg, Dorchester, DT2 8ZD, Dorset, U.K.
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    • Present address: School of Conservation Sciences, Bournemouth University, Dorset House, Talbot Campus, Fern Barrow, Poole, Dorset BH12 5BB, U.K.


†Tel.: +44 (0) 1502527751; fax: +44 (0) 1502513865; email: gordon.copp@cefas.co.uk

Abstract

European countries in general, and England in particular, have a long history of introducing non-native fish species, but there exist no detailed studies of the introduction pathways and propagules pressure for any European country. Using the nine regions of England as a preliminary case study, the potential relationship between the occurrence in the wild of non-native freshwater fishes (from a recent audit of non-native species) and the intensity (i.e. propagule pressure) and diversity of fish imports was investigated. The main pathways of introduction were via imports of fishes for ornamental use (e.g. aquaria and garden ponds) and sport fishing, with no reported or suspected cases of ballast water or hull fouling introductions. The recorded occurrence of non-native fishes in the wild was found to be related to the time (number of years) since the decade of introduction. A shift in the establishment rate, however, was observed in the 1970s after which the ratio of established-to-introduced species declined. The number of established non-native fish species observed in the wild was found to increase significantly (P < 0·05) with increasing import intensity (log10x + 1 of the numbers of fish imported for the years 2000–2004) and with increasing consignment diversity (log10x + 1 of the numbers of consignment types imported for the years 2000–2004). The implications for policy and management are discussed.

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