Beachgoers urged to keep eye out for unwanted weed

The unwanted beach weed sea spurge (Euphorbia paralias) has turned up at two sites in the Far North prompting a call for beachgoers to be on the lookout and report any potential sightings.

Northland Regional Councillor Peter-Lucas Jones says the weed – which could have serious impacts on our coastal environments – has been confirmed at two locations on Te Oneroa-a-Tōhe / Ninety Mile Beach; one near Ahipara and one just north of Waipapakauri.

There is currently only one other known site of sea spurge in Northland, located on the Pouto peninsula, but Cr Jones - one of two Te Raki Māori constituency representatives on the council – says there is potential for it to turn up at other sites along the west coast.

The weed is native to Europe, but it is likely to have arrived in New Zealand on ocean currents from Australia, where it has become a major weed on their southern coastline.

“It’s causing major environmental damage at many Australian beaches, displacing native plants and changing natural patterns of sand movements. It has the potential to overrun our native dune species and threaten the habitats of native birds.”

Councillor Jones says an adult plant can produce between 5000 and 20,000 buoyant and salt-tolerant seeds every year, and these can travel long distances on ocean currents. This means there is an ongoing risk of seeds making their way over and establishing along our long stretch of coastline, with the west coast being the most at risk.

He says sea spurge looks like a small shrub and typically grows up to 50 centimetres in height although it can sometimes reach up to one metre.

“It has tightly packed leaves that are bluish green in colour, with the stem having often a red tinge at the base. It has a milky sap, which is toxic to people and animals and may cause temporary blindness.”

Its flowers are composed of yellowish green petal less flowers found in clusters while leaves are stalkless, hairless, alternate, crowded and overlapping along the stems.

Councillor Jones says to date all plants have been removed from known locations and some beach survey to the north and south of these sites has been completed.

“The known sites will be searched again, every four months, and any new seedlings found will be controlled to prevent future seeding. Wider beach surveillance is also needed.”

Sea spurge is classified as an Unwanted Organism and the Ministry for Primary Industries (MPI) is the lead agency for sea spurge management. The Ministry works with the Department of Conservation and regional councils to determine the best way to deliver the necessary control and surveillance work in each region.

Lisa McNab, chair of Te Oneroa-a-Tōhe Beach Board, says: "Our beach is more than just a stretch of sand; it’s a taonga handed down through generations. Protecting Te Oneroa-a-Tōhe is a responsibility we all share. Whether you’re walking the shoreline, talking with your whānau, or joining our hui, your actions make a difference."

"Together, we can stop the spread of sea spurge and safeguard the beauty and mauri of our coastline for those who come after us. This is our chance to show the strength of our kaitiakitanga. Let’s rise to the occasion and protect what’s ours," McNab says.

Councillor Jones says sea spurge is most likely to grow in areas where debris is washed up during high tides and storms because this is where the floating seeds may be deposited.

“Anyone who thinks they have found sea spurge should report it as soon as possible using the Ministry for Primary Industries Pests-and-Diseases hotline on 0800 80 99 66.”

People should note the location as accurately as possible – GPS coordinates are ideal, or you can open Google Maps and drop a pin on the map (and/or screen shot your location on the map). You can also use the iNaturalist app to mark potential sites.

“Take some clear photos and please do not disturb the plants as the sap is toxic, and you could also spread the seeds via your clothing and equipment. Plants can also regrow from root fragments.”

Councillor Jones says sea spurge looks similar to the rare native spurge, waiūatua / waiū-o-Kahukura (Euphorbia glauca), however, the native spurge has much larger leaves that are 30–80mm long. The New Zealand linen flax (Linum monogynum) and the sand daphne / toroheke (pimelea villosa) which grow in the coastal environment are also similar.

A Biosecurity New Zealand fact sheet PDF on sea spurge can be downloaded here (296KB).