Biofouling management

Marine pests and diseases introduced to New Zealand on vessel hulls (biofouling) are a threat to our marine environment and resources. From May 2018, all commercial and recreational vessels arriving in New Zealand will need to have a clean hull. Find out about the new biofouling requirements.

New Zealand's new biofouling requirements

From May 2018, vessels must arrive in New Zealand with a 'clean hull'. This means:

  • Vessels staying up to 20 days and only visiting designated ports (places of first arrival) will be allowed a slight amount of biofouling (slime layer, goose barnacles, and up to 5% cover of early biofouling depending on the area fouled).
  • Vessels staying longer than 20 days or visiting places that aren't places of first arrival will only be allowed a slime layer and goose barnacles.

The clean hull thresholds are not being enforced until May 2018. However, MPI can take action now on vessels that pose a severe biofouling risk.

View a diagram explaining severe biofouling risk [PDF, 613 KB]

Guidance for self- assessing a vessel’s risk profile [PDF, 195 KB]

Vessels that are likely to have biofouling

After May 2018, if we assess your vessel as likely to have more biofouling than the allowed threshold, we'll inspect your vessel's documents for:

  • biofouling maintenance records
  • operational history.

In some cases, we may have divers inspect the vessel underwater.

Vessels over the biofouling threshold

If your vessel has too much biofouling (more than the 'clean hull' threshold), MPI may:

  • restrict entry of your vessel to New Zealand
  • reduce your New Zealand itinerary
  • ask you to clean your vessel offshore using an approved treatment or within 24 hours by an approved provider in New Zealand.

These measures will be at the expense of the vessel owner or operator.

What is a clean hull?

A clean hull has no more than a slime layer coating of marine growth on the hull and submerged niche areas – for example, sea chests, bow thrusters, seawater systems, and propeller shafts. However, the clean hull threshold (the allowed amount of biofouling) is based on a vessel's itinerary and the types of marine species present.

Allowable amounts of biofouling are set out in the Craft risk management standard (CRMS) for biofouling on vessels arriving to New Zealand. Descriptions and images of allowable amounts of biofouling, and biofouling management options are in the guidance document for the CRMS.

Download the craft risk management standard for biofouling [PDF, 241 KB]

Download the guidance document for the CRMS [PDF, 1.5 MB]

Download the craft risk management standard - frequently asked questions [PDF, 1.8 MB]

Alignment with international guidelines

New Zealand's CRMS requirements are based on the International Maritime Organization's Guidelines for the control and management of ships' biofouling to minimize the transfer of invasive aquatic species. These provide examples of biofouling management best practice.

Download the IMO's biofouling guidelines

How to comply with new requirements

You'll be able to meet the new clean hull requirements by doing one of the following (and having documentation to prove it):

  • Cleaning the vessel hull less than 30 days before arrival in New Zealand or within 24 hours of arrival (you must have proof of a cleaning facility being booked within 24 hours of arrival).
  • Doing continual maintenance.
  • Applying MPI-approved treatments to the hull.

Continual maintenance

Continual maintenance involves ongoing management of biofouling, including applying an antifouling coating, on the hull and niche areas.

Approved biosecurity treatments

These are treatments that remove or kill all organisms on the hull and niche areas, for example by applying chemicals or heat.

Currently, MPI has not approved any biosecurity treatments. But some treatments will be approved before the new biofouling rules start in May 2018. We are developing the:

  • details for approved cleaning and treatment systems
  • process for getting MPI approval.

To discuss becoming an approved treatment provider, email

When available, you'll find approved treatments and providers on our registers and lists page.

Making alternative arrangements to meet the standard

MPI is happy to consider alternative biofouling management arrangements to the CRMS. These need to be detailed in a specific plan called a Craft Risk Management Plan that must:

  • be approved by MPI
  • include steps to reduce risk to the equivalent level of arriving with a clean hull.

Guidance on developing a Craft Risk Management Plan [PDF, 949 KB]

Providing evidence of compliance

Before you arrive, MPI may ask to see photographic (or video) evidence of the cleaned hull and niche areas. We may also ask to see your biofouling management plan and record book, including:

  • dates of dry docking
  • antifouling system application or installation
  • vessel operational history
  • evidence of independent inspections and ongoing maintenance (such as cleaning or treatment) by suitably qualified people.

Guidelines for diving service providers inspecting vessels arriving to New Zealand [PDF, 2 MB]

See guidance on what to put in a biofouling management plan [PDF, 1009 KB]

Specific advice for your vessel type

Check what you'll need to do to get your vessel ready to meet the new clean hull requirements.

Short-stay vessels

Short-stay vessels are those staying in New Zealand for less than 21 days, and only visiting approved ports of first arrival.

Most short-stay vessels are commercial vessels, including

  • trading ships
  • bulkers
  • cruise vessels
  • container ships
  • commercial cargo vessels.

Long-stay vessels

Long-stay vessels are those staying 21 days or longer, or wanting to visit areas not approved as ports of first arrival.

Long-stay vessels typically include:

  • yachts and other recreational vessels
  • project vessels
  • drill rigs
  • tugs
  • barges
  • research vessels
  • defence vessels.

Vessels arriving for refit or haul-out

If you know your vessel is fouled and you want to have it hauled out or re-fitted in New Zealand, before you arrive you must:

  • book an MPI-approved facility or in-water cleaning or treatment provider
  • give MPI evidence of your booking with the provider (the booking time must be within 24 hours of arrival).

There are currently no MPI-approved providers. Some will be approved before the new biofouling rules start in May 2018. When available, you'll find providers on our registers and lists page.

MPI can help you prepare

MPI can help you:

  • develop MPI-endorsed codes of practice for your industry group to help members comply with the new requirements
  • develop an MPI-approved Craft Risk Management Plan for your vessel
  • check if the biofouling on your vessel hull is acceptable
  • get advice on acceptable hull preparation, cleaning, treatment and inspection.

For further details, email

Find out more

Who to contact

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