A DoC-led spartina control operation will focus on an infestation of the plants in the inter-tidal areas of Coromandel Harbour later this month.

Spartina is a fast-growing, salt-tolerant grass that can grow to two metres tall.

Although it was originally planted in locations across New Zealand in the 1940s to stabilise land for reclamation, it has become an aggressive and persistent invader of inter-tidal mudflats, like those found around Coromandel Harbour.

Spartina traps silt and sand, impacting the open mudflats needed by many migratory protected bird species such as the kuaka/bar-tailed godwit, moho pereū/banded rail, and tūturiwhatu/dotterel, as well as some shellfish varieties.

DoC’s Coromandel biodiversity ranger Jamie Carey said the infestation of the plant in Coromandel Harbour needs to be addressed, prompting an aerial herbicide operation his team has planned for February.

“When it comes to spartina, ‘do nothing’ is not an option,” says Jamie. “We need to control this plant, or it will spread and further compromise the biodiversity values in the harbour.

“If we don’t address this infestation quickly, we’ll lose valuable habitat for our native species.”

The operation will involve using a helicopter to apply the herbicide (Halyoxfop), which will rely on a patch of good weather with minimal wind. Jamie says this will be visible to people in and around the harbour, but there is no need for concern.

“We want to be transparent about this work; even though the aircraft will only be deployed for a few hours, people may wonder what it’s doing flying at such low levels.

“In short, it’s helping us protect native species habitat by addressing the spartina issue in the harbour.”

Monitoring will be undertaken after the operation to ensure water quality in the harbour has not been compromised, as per DoC’s consent to use the product.