Protecting the Top of the South from the threat of marine pests

While most New Zealanders enjoyed their summer break, a team of Boffa Miskell biosecurity consultants and divers were out and about inspecting the hulls of boats for marine pests across the Marlborough Sounds, Abel Tasman and Nelson Bays.

Marine pests can do serious harm to our natural ecosystems. They can establish quickly in an area, out-competing and displacing the native species that live there. Marine pests also pose significant risks to the economy, especially aquaculture and marine industries, tourism, recreational and commercial fishing, as well as having impacts on human health. Most marine pests arrive in New Zealand on vessel hulls. New Zealand’s marine biosecurity protocols focus on stopping them from arriving in our waters, as well as reducing the risk of spread once they get here.

The Top of the South Island faces potential marine pest invasions, particularly through fouling on the hulls of recreational vessels. The Top of the South summer marine pest surveillance programme aims to educate boat users on the risks posed by marine pests, minimise the introduction of marine pests to the regions (such as Exotic Caulerpa, currently present in Northland and Auckland) and reduce the spread of species already present (such as Mediterranean fanworm, pictured below).

The hull surveillance programme is funded by the Top of the South Marine Biosecurity Partnership, coordinated by Boffa Miskell and undertaken by specialist divers from Wai Dive. The Partnership is a collaboration between Nelson City Council, Tasman District Council, Marlborough District Council, Greater Wellington Regional Council and Ministry for Primary Industries. In addition, key partners such as the Department of Conservation, the local aquaculture industry, port companies and mana whenua provide their expertise to improve regional marine biosecurity planning, advocacy, and action through collaboration.

Boat owners must ensure their vessels and equipment are not harbouring any marine pests. A vessel is considered high-risk when more than 5% of the hull’s surface is covered with biofouling. By taking an interest in marine biosecurity, learning about marine pests and following simple biosecurity procedures, boat owners play a vital role in preventing the invasion and spread of marine pests in the Top of the South. Vessels should ideally be inspected and cleaned appropriately every 3-6 months before leaving home port. 

The first round of hull surveillance inspections were carried out in early January. Divers targeted areas popular with boaties, including Abel Tasman National Park and Queen Charlotte Sound. Hulls and niche areas (areas that are more likely to harbour marine pests) such as the keel, rudder, trim tabs, propeller shaft, pipe outlets, bow-thruster tunnels, and hard-stand support strips of vessels are inspected thoroughly for marine pests. A second round of surveillance is planned for late January 2024, including over the Nelson Tasman Anniversary weekend.