Sun. Jun 16th, 2024


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Column: Stop marine pests from spreading

3 min read
marine pests

Exotic caulerpa has now been found in the Bay of Islands, in several locations in the Hauraki Gulf, at Ahuahu Great Mercury Island, and on the western coast of the Coromandel Peninsula. Photo: Northland Regional Council

One of the challenges that the people trying to help stop marine pests from devastating our coastline environments face is that they are out of sight, out of mind, writes marine biosecurity expert Aless Smith

Unlike something like gorse in our paddocks or rats in the ceiling, which are hard to ignore, it’s difficult to appreciate how much damage marine pests can do until you are face-to-face with the evidence.

In Northland, we are dealing with the invasive seaweeds Caulerpa brachypus and Caulerpa parvifolia. There is still no consensus as to how it got to New Zealand but now that it’s here, managing it is a huge job. There is a lot of great work going on, but we need to do everything we can to stop pests like this from spreading to new spots if we have any chance at all.

In May, we spent a few days at the Hutchwilco Boat Show in Auckland talking to people about how important it is that they do three things:

Check and clean their gear before they move: The before-you-move part is important because we don’t want anyone taking even a tiny fragment of something such as exotic caulerpa to a new location.

Keep hulls clean of biofouling: This is mostly for moored boats because marine pests can hitchhike on boat hulls without you knowing it.

Be our eyes on the water: Know what marine pests look like and if you see something that looks unusual, please report it ASAP. We’d rather get reports of things that don’t turn out to be exotic caulerpa or Chinese mitten crab than not. Getting sightings early gives us more chance of responding to any incursions quickly.

If boaties could see the impact marine pests have on the places they love, they would quickly understand how important it is to be vigilant about checking and cleaning at all times. This is why the Clean Below Good to Go campaign was created – to emphasise the significance of regular maintenance and cleanliness and to help raise awareness of the role biofouling plays in the spread of marine pests.

For more information, visit

marine pests
Aless Smith. Photo: Supplied

Aless Smith is the marine biosecurity specialist at the Northland Regional Council. She is a scientific diver and helps to inspect some of the 2000 hulls in Northland each year. As part of the Top of the North partnership, Aless has assisted with getting the word out about all things marine biosecurity. Her favourite place to spend time on the water is out at Aotea Great Barrier Island.

Join the webinar

Aless is hosting a marine pests ID webinar with the Clean Below Good to Go team from 10am to 11am on Thursday, 6 June. Register at

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