This assessment estimates potential present value impacts of didymo on New Zealand’s commercial eel fisheries, municipal, industrial and agricultural water intakes, community, municipal and domestic drinking water, local recreation values, international and domestic tourism expenditure, local and national existence values and existence values associated with extinction of native species, over the eight years 2004/05 to 2011/12, to total:
$57.798 million under the low impact scenario;
$167.233 million under the medium impact scenario; and
$285.132 million under the high impact scenario.
Weighting the three scenarios by their relative probabilities suggests expected present value total impacts over this period of $157.599 million.
Total impacts are dominated by reduced recreation values, loss of existence values associated with extinction of native species and reduced tourism expenditure, followed by increased costs for water intakes and reduced local and national existence values. Total impacts are greatest in the North Island and central South Island. Although the lower South Island has the largest amount of highest risk environment for survival of didymo and is where impacts occur earliest, the central South Island and North Island have substantially larger human populations to suffer reduced recreation and existence values.
Sensitivity analysis
Without the loss of native species, present value total impacts over the period 2004/05 to 2011/12 would be reduced to between $39.525 million and $230.312 million.
A two year delay to the arrival of didymo in the North Island would reduce the present value total impacts incurred over the longer period 2004/05 to 2013/14 by between $5.024 million and $62.419 million (9 and 22 per cent). Slowing the spread of didymo through each region (from five to seven years) would reduce the present value total impacts incurred over the longer period 2004/05 to 2013/14 by between $26.302 million and $142.748 million (46 and 50 per cent)
More here: http://www.biosecurity.govt.nz/pests-diseases/plants/didymo/economic-impact.htm
