New standards on fouled boat hulls will help in the battle to keep marine pests out of the region, Nelson City Council says.
It said checks of about 600 boats in the Nelson marina revealed 45 had fouled hulls and the owners were now being asked to clean them up.
A council spokesperson said things were about to get tougher for boat owners who failed to keep the hulls of their vessels clean, with more stringent enforcement by the Ministry for Primary Industries border biosecurity staff looming.
The council is part of the Top of the South Marine Partnership, set up to improve marine biosecurity management.
It includes representation from the Nelson, Tasman and Marlborough councils, the Ministry for Primary Industries, Department of Conservation, the aquaculture industry, port companies and tangata whenua.
Nelson City Council environment manager Clare Barton said the new standards were an important addition to protecting the region from harmful marine pests.
"Harmful organisms need human assistance to reach New Zealand shores; the usual pathway is as fouling on vessels or marine structures."
International agreements have been in place around the release of ships' ballast water for some years, Ms Barton said.
The council also had a strong working relationship with Port Nelson, where a growing number of vessels were now moored away from the marina.
The moorings were managed by the council through a resource consent process, and were currently fully allocated, she said.
Ms Barton said the new border standards required vessels visiting from overseas to have clean hulls.
The new border standard will be enforced by Ministry for Primary Industries border biosecurity staff.