Marine Pest of the Week

Marine Pest of the Week

Marine Pest of the Week is a series that helps you recognise the pests threatening New Zealand’s waters, understand their impact, and learn how to protect our marine environment.
Pest of the Week - Red seaweed
Marine Pest of the Week

Red Seaweed (Asparagopsis taxiformis)

Why is it a problem? Very similar to a New Zealand native, Asparagopsis armata which has harpoon-like structures on side bra...
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February 2026

Northern Pacific Sea Star (Asterias amurensis)

Why is it a problem? The Northern Pacific sea star is a voracious predator that will feed on a wide variety of other marine ...
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Marine Pest of the Week

Marine Pest of the Week: The European Shore Crab (Carcinus maenas)

Why is it a problem? In some areas where it has been introduced, the European shore crab can reach densities of up to 200 pe...
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Marine Pest of the Week

Marine Pest of the Week: Chinese Mitten Crab (Eriocheir sinensis )

Why is it a problem? Know the difference and help protect our best boating spots! In its introduced range, the Chinese mi...
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Marine Pest of the Week

Marine Pest of the Week: Asian Shore Crab

Why is it a problem? The Ministry for Primary industries says that this crab eat species that are important to our rocky int...
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Marine Pest of the Week

Marine Pest of the Week: Asian Clam (Potamocorbula amurensis)

Why is it a problem? The Asian clam can occur in very high densities; over 25,000 per square metre. In some parts of San Fra...
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Marine Pest of the Week

Marine Pest of the Week: Asian Brown Mussel

Why is it a problem? The Ministry for Primary Industries says that the green-lipped mussel is culturally and economically im...
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Marine Pest of the Week

Marine Pest of the Week: Aquarium Caulerpa (Caulerpa taxifolia)

Why is it a problem? The aquarium type is cold-tolerant, fast growing and, in natural environments, can form extensive, dens...
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Marine Pest of the Week: Clubbed Tunicate ​(Styela clava)
Marine Pest of the Week

Marine Pest of the Week: Clubbed Tunicate ​(Styela clava)

The clubbed tunicate prefers to grow on marine structures and boat hulls, affecting your boat’s performance and hitchhiking t...
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Marine Pest of the Week

Marine Pest of the Week: Sea Squirt (Clavelina)

Clavelina oblonga and Clavelina lepadiformis are two types of sea squirt, or ascidian, that have recently established in New ...
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Native seagrass is a beneficial species that can be difficult to tell apart from the invasive seaweed exotic caulerpa. // Photo credit: Shaun Lee
Boat Brief

Marine pest or native look-alike?

Know the difference and help protect our best boating spots.  With an army of boats out on the water this summer, it’s a g...
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Marine Pest of the Week - Asian Kelp (Undaria pinnatifida)
Marine Pest of the Week

Marine Pest of the Week – Asian Kelp (Undaria pinnatifida)

A fast grower that forms dense colonies on any hard surface - including your boat, shells, reefs, wharf piles, aquaculture st...
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Marine Pest of the Week
Marine Pest of the Week

Marine Pest of the Week – Exotic Caulerpa

These species of Caulerpa demonstrate aggressive overgrowth qualities when introduced outside of their native ranges. This qu...
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Marine Pest of the Week

Marine Pest of the Week – Mediterranean Fanworm ​(Sabella spallanzanii)

With an ability to pack in 1,000 individuals per square meter, Mediterranean fanworm makes it difficult for other species in ...
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Marine Pest of the Week

Marine Pest of the Week – Japanese Mantis Shrimp (Oratosquilla oratoria)

An aggressive competitor with a dangerous but impressive ‘karate chop’ ability to stun prey. It lives in burrows in the sand ...
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Marine Pest of the Week

Marine Pest of the Week – Eudistoma Australian Droplet Tunicate

With a slimy snot-like appearance this species can form big colonies on rocks. Intrigued? Read more.
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January 2026

Marine Pest of the Week – Asian Paddle Crab (Charybdis japonica)

The Asian Paddle Crab is in some parts of New Zealand we don't want it to spread.
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