Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract Full Text

The economic cost of invasive non-native species on Great Britain.


The impact of Invasive Non-Native Species (INNS) can be manifold, ranging from loss of crops, damaged buildings, and additional production costs to the loss of livelihoods and ecosystem services. INNS are increasingly abundant in Great Britain and in Europe generally and their impact is rising. Hence, INNS are the subject of considerable concern in Great Britain, prompting the development of a Non-Native Species Strategy and the formation of the GB Non-Native Species Programme Board and Secretariat. A number of estimates of the economic impact of INNS on various countries, including the UK, exist, but the detail in many of these estimates is lacking and the impact on different sectors of the country is largely unknown. This research estimates the current annual cost of INNS to the British economy. The report provides assessments of the economic cost of INNS to twelve sectors and the report contains detailed examples for three species (Japanese knotweed, signal crayfish and floating pennywort). Five case studies are also included to demonstrate the costs of eradication at different stages of invasion. The report only considers negative economic impacts of INNS, although it is acknowledged that non-native species, including some invasive ones can make a positive contribution to the economy. Various methods were used to secure data for economic estimations. References of relevance to over 500 non-native species were gathered from the scientific and grey literature as well as the internet. A detailed questionnaire was sent to key organisations, primarily to develop contacts but also to gather initial information. The collected information was used to estimate the costs, partially based on calculations for individual species, which was anonymously reviewed by selected experts from each of the sectors. The total current annual cost of INNS to the British economy is estimated, when corrected for double counting, at £ 1,291,461,000 to England, £ 244,736,000 to Scotland and £ 125,118,000 to Wales. Therefore the total annual cost of INNS to the British economy is estimated at approximately £ 1.7 billion. In this work, where solid evidence was not available, assumptions based on the biology and ecology of the species involved were used to extrapolate costs. When assumptions had to be used, the figures that were used were intentionally conservative and it has been explicitly stated that they were assumptions. In the anonymous peer review process the calculations and assumptions were challenged, corrected or accepted. This report focused on direct costs as these could be most accurately estimated, however if indirect costs do exist to a similar extent to that found in the meta-analysis, the value of these could be very significant. However, the indirect costs have not been sufficiently explored to support or refute this suggestion. As INNS are becoming more widespread and the economic impact is expected to increase, the effect of the extent of the invasion on control costs was investigated in five case studies (Asian long-horned beetle, carpet sea squirt, water primrose, grey squirrel and coypu). These case studies revealed an exponential increase of the cost of control as an invasion progresses, and demonstrated the benefits of intervention at an early stage, as well as the long-term cost savings if eradication is undertaken early in the invasion process.