Coastal Restoration Trust of New Zealand

Coastal Dune Ecosystem Reference Database

Sea Spurge (Eurphorbia paralias) Annual operational report 2019/2020 Technical Report

McKinnon, F.
Publisher / Organisation
Waikato Regional Council
Prepared for Ministry of Primary Industries Contact for Services 16738 Sea spurge (Euphorbia paralias) eradication response at Aotea, Waikato. September 2013 Sea spurge was discovered in 2012 at a remote location three kilometres north of Potahi Point and the Aotea Harbour entrance on the west coast of the Waikato region, this site is known as the detection site. Until 2019 this was the only known sea spurge infestation in New Zealand. Sea spurge is a hardy European shrub that invades and thrives in coastal dune environments. It’s seeds float and can be carried by ocean currents. It is probable the sea spurge infestation in Aotea originated from seed that floated from Australia. Sea spurge has caused major environmental problems in Australia. It was first found in Western Australia and has since spread throughout the south-east coastline, including Tasmania and the islands of Bass Strait, and on the beaches of New South Wales coastline. It is believed sea spurge was introduced to Australia in ship ballast water. Sea spurge is a highly invasive dune shrub, it forms dense stands in the foredune and backdune environments displacing native plants and animals and changing sand movement patterns. Sea Spurge poses a serious threat to New Zealand’s dune systems. A working group has been established to collaboratively manage and eradicate sea spurge in New Zealand. This group is led by the Ministry of Primary Industries (MPI) and includes the Waikato Regional Council (WRC) and Department of Conservation (DoC). The group plans to prevent further seed production by maintaining the infestation site at zero density and exhausting the seed bank. The detection site is a dynamic coastal environment where the risk of erosion and movement of materials from the site is high. For this reason, the coastline 15km north and south of the infestation is also surveyed for sea spurge.