About Marine Pests

Marine pests are species that are not indigenous to New Zealand, but which have been introduced to our waters by human activities and have the potential to cause significant impacts on our marine environments and resources. Many hundreds of species have been introduced to New Zealand. Most have arrived with shipping, either attached to the submerged surfaces of ships (“biofouling”) or in the ballast water carried by modern vessels to maintain stability. Not all of the non-indigenous species introduced to New Zealand are capable of survival here and, fortunately, many of those that do have relatively little impact. Some, such as the Pacific oyster (Crassostrea gigas) and Chinook Salmon (Oncorhyncus tshawytsha) are even valued in New Zealand as food items and form the basis of important aquaculture industries. Nevertheless, some of the species that arrive in New Zealand thrive and can displace indigenous New Zealand species, alter coastal habitats, affect human health and damage our fishing, aquaculture and other maritime industries.

As a small island nation, New Zealand is heavily dependent on maritime trade and is particularly vulnerable to harmful organisms and pathogens that are introduced by shipping. As global shipping networks expand and diversify, a greater number of marine pests have the opportunity to reach New Zealand.

Examples of marine pests and their impacts

The Asian date mussel, Musculista senhousia (pictured), is a prime example of a species that modifies native habitats. In soft sediments it settles in very dense patches, sometimes numbering more than 10,000 individuals per square metre. The mussels produce threads that entangle each other to form a mat over the sediment surface. Fine sediment collects in the mats creating a silty layer that can smother filter feeders like cockles and pipi.

Managing the threat from marine pests

Biosecurity is the exclusion, eradication or effective management of risks posed by pests and diseases to New Zealand’s economy, environment and human health. MAF Biosecurity New Zealand is the government agency charged with leadership of the New Zealand biosecurity system, including marine biosecurity. However, all New Zealanders have a role to play...

Find out about New Zealand research on marine pests and marine biosecurity

Some definitions

Cryptogenic – a species whose geographic origin is uncertain (i.e. it can not be shown to be indigenous or non-indigenous to New Zealand).

Endemic – a species that is native to the New Zealand biogeographic region and which does not occur anywhere else in the world. 

Indigenous – a species that is native to the New Zealand biogeographical region historically and has not been introduced by human activities.

Non-indigenous – a species that is known or suspected to have been introduced to New Zealand as a result of human activities.