• pre-border
• border
• post-border

The Ministry of Fisheries focuses on preventing introductions of marine species, because eradicating or managing pests is extremely difficult once they become established. Accordingly, we direct most effort towards pre-border and border control, and towards the greatest risks, which are:

• ballast water - see Regulating for ballast water exchange
• hull fouling and cleaning - see Proposed hull cleaning guidelines

Regulating for ballast water exchange
Ships carry ballast water for stability. Ballast that is pumped into a ship in one port will invariably contain organisms from that port. These can include microscopic organisms, larval stages of organisms and even whole fish. When the ballast water is discharged, sometimes as much as 50 000 tonnes for a bulk carrier, those organisms are discharged and may establish in the host environment. We have moved to minimise risks to the marine environment of ships emptying ballast water straight into our seas.

In May 1998, voluntary guidelines for ballast water were replaced with an Import Health Standard (IHS). Under the IHS, ballast water collected at a foreign port cannot be discharged into New Zealand waters unless it has been exchanged in areas free from coastal influence, preferably mid-ocean. Mid-ocean water contains fewer organisms such as planktonic larvae of crabs, sea-stars, fan worms, shellfish, spores of seaweeds, and toxic algae and is unlikely to contain organisms that can thrive in a coastal environment. Exchange only reduces the risk to a certain extent, as some water from the foreign port always remains in the ballast tanks.

The Import Health Standard names Tasmania and the port at Melbourne, Australia as 'higher risk areas' due to the presence of the Northern Pacific sea-star and the toxic algae Gymnodinium catenatum, which bloomed in New Zealand during 2000/2001. Extra care is taken to ensure ballast from these places has been exchanged before discharge

The Ministry of Fisheries is identifying areas that are on the high seas and/or free from coastal influence where vessels en route to New Zealand can exchange their ballast water to further minimise the biosecurity risks when it is discharged. Providing ships' masters with information on suitable exchange areas will minimise the quantity of exotic coastal marine organisms in their tanks when they reach New Zealand.

Proposed hull cleaning controls
Fouling (or encrusting) organisms grow on the external areas of boats. If a boat arrives in New Zealand with fouling organisms on it they may be knocked off, scraped off deliberately when a hull is cleaned or breed in New Zealand waters, resulting in an introduction. The threat is thought to be significant-it has been estimated that over 60% of the exotic marine species now in New Zealand arrived here on vessel hulls.

The Ministry of Fisheries Biosecurity group is developing controls to ensure fouling organisms removed from vessel hulls during cleaning are not washed back into the sea.

The proposed controls are being developed in collaboration with the Ministry for the Environment.

The aim is to ensure the fouling material removed is contained, treated and properly disposed to reduce the chance of viable spores or fragments finding their way back into coastal waters.

For more information contact Liz Jones at liz.jones@fish.govt.nz