Invasive marine species

Marine pests are species that are not indigenous to New Zealand, which have been introduced to our waters by human activities (as well as less-commonly through natural dispersal), and which have the potential to significantly damage marine ecosystems and species.

Many marine invasive species have become established in New Zealand. Some have been in the country for a long time, such as the Pacific oyster. Others are more recent arrivals, such as Undaria pinnatifida (Japanese kelp). Both the Pacific oyster and Japanese kelp are now well-established and have been adopted into the country’s aquaculture industry.

In 2008, 288 non-indigenous species were recorded. 2623  These include algae (both large and microscopic), barnacles, crabs, bryozoans, sea squirts, mussels and other molluscs. There was a significant rise in the number of detections between 2001 and 2010, likely due in part to the active surveillance programmes put in place during that period, and greater awareness of the negative impacts of marine pests.

The Asian paddle crab (Charybdis japonica) is a very aggressive species and competes directly with New Zealand’s native paddle crab. It was first noticed, when some of the crabs were caught in flounder nets in the Rangitoto channel, on the outskirts of the Waitematā Harbour. It is now well established in the Auckland and Whangarei harbours, and appears to have displaced native crab species in these locations. 2625

The Ministry for Primary Industries has identified six unwanted marine organisms which are highly invasive and of particular concern, being the Chinese mitten crab (Eriocheir sinensis), Mediterranean fanworm (Sabella spallanzanii), Northern Pacific seastar (Asterias amurensis), European shore crab (Carcinus maenas), Asian clam (Potamocorbula amurensis) and Caulerpa taxifolia (a marine aquarium weed). Of these, the fanworm has become established in New Zealand since it was declared an unwanted organism. There are also numerous diseases of fish, molluscs and shellfish that New Zealand is mostly free from. 2626  Some of these can have a devastating impact, such as the Ostreid herpesvirus (OsHV-1) which is discussed further in the Aquaculture section.

The European shore crab (also known as the European green crab, Carcinus maenas) is an unwanted organism that has not yet reached New Zealand. It is a highly adaptable invasive species, with a wide tolerance to different environments, which makes it a significant threat to New Zealand’s inshore habitats. It is a voracious predator which eats mussels, crabs, oysters, limpets, barnacles and worms, as well as juvenile crabs and shellfish, including scallops. The European shore crab has the potential to significantly alter ecosystems, causing mortality in native crab and shellfish populations, and it has been implicated in the decline of native shellfish populations overseas. There is a risk that juvenile crabs or crab larvae could be transported via ballast water to this country. 2629

The Ministry for Primary Industries, in collaboration with NIWA, has developed a new web portal called the Marine Biosecurity Porthole. 2630  This provides access to surveillance and other records of marine pests in New Zealand waters. These data come from a range of sources including a national series of Port Biological Baseline Surveys and the results of a Marine High Risk Site Surveillance programme (both of them are discussed below), as well as NIWA’s Marine Invasive Taxonomic Service (which identifies marine specimens on behalf of MPI) and other verified observations. This portal plays an important role in distributing information about current knowledge on non-native marine organisms in New Zealand.

  1. Kospartov M, 2008





Last updated at 2:11PM on February 25, 2015