​Tensions between mana whenua and biosecurity on pest seaweed controls

A lack of engagement and restrictions on customary fishing rights created tensions in biosecurity discussions for pest seaweed at the Hauraki Gulf forum.

At the forum meeting on August 22, Biosecurity New Zealand's director of readiness and response John Walsh presented on Caulerpa, a highly invasive pest species of seaweed.

Walsh said it had been about two years since Caulerpa was first established in New Zealand waters and had spread across 90 hectares in Blind Bay at Aotea Island.

“We think it probably arrived from Australia. It could have caught on the chain of an anchor, the anchor dropped and the seaweed jumped off,” Walsh said.

Walsh said Caulerpa was spread through human mediation which meant one of the best controls was to prevent things like fishing in the area.

A controlled area notice (CAN) was placed on three harbours at Aotea island after the spread, preventing fishing, seafood gathering or dropping anchor.

“We are quite concerned about it because of the speed at which it’s growing… we are unlikely to be able to eradicate it so we have been focused on how to prevent the spread.”

Caulerpa has not been found in the Hauraki Gulf from recent surveys but Walsh said without adequate controls it would spread.

One method of pest control that had shown to be effective was applying salt directly to Caulerpa.  Walsh said, “who would have thought you would use salt to kill something in the sea but apparently it does.”
Walsh said the downside was the “monstrous” volume of salt needed. 

Aotea local board member Valmaine Toki said restrictions on fishing at Aotea island had distressed the community.

“If you could reconsider, the community would really appreciate it,” Toki said.

Toki said the community was frustrated with the engagement from the Ministry for Primary Industries for being lacklustre and generic.

“When do local communities get to provide their solutions… The best way would be to get local people and mana whenua to do the monitoring.” 

Toki said by the time authorities arrived after community complaints of boats breaking restrictions the boat was already gone. 

Tangata whenua Terrence Hohneck said the news was devastating and that he did not believe people offending came from the island.

“I do not believe our people should be denied their customary rights,” Hohneck said.

John Walsh responded to concerns by saying engagement had occurred through an ambassador programme for the island where four mana whenua entities had been consulted.

“This could be a $1 million problem now or a $200 million problem in two years,” Walsh said.
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The CAN at Aotea island expired in June however Biosecurity New Zealand has extended it till the end of September.