WELLINGTON, Jan. 12 (Xinhua) -- Ships entering New Zealand waters will have to meet tougher new restrictions on controlling marine pests under international and domestic rules.
New Zealand has formally joined an international agreement of managing ships' ballast water, becoming the 54th country to join the Ballast Water Management Convention under the International Maritime Organization, the Ministry for Primary Industries (MPI) said Thursday.
The convention, which will enter into force in September, would help to prevent the spread of harmful marine species, MPI manager of border and biosecurity systems, Andrew Bell said in a statement.
Ballast water, which stabilizes a ship during a voyage, could contain millions of aquatic or marine microbes, plants and animals, which were carried across the globe and could be introduced to new locations when ships discharged their ballast.
"Releasing this water into a new environment can also release unwanted marine species," Bell said.
The convention would require all vessels to deal with their ballast water before discharging it.
However, the majority of introductions of harmful marine species to New Zealand were through biofouling -- marine life growing on vessel hulls.
New Zealand had new rules on biofouling, coming into force in May next year, stipulating that all vessels arriving in New Zealand must have a clean hull, said Bell.