This information explains what is being done to try and prevent the introduction of exotic species, and gives information about the kinds of unwanted species we are looking for and how you can help by reporting suspected pests. Unfortunately some exotic marine species have already arrived in New Zealand and have become established, and their impact is unknown. They may affect the balance of natural ecosystems by pushing out native species which could affect the environment, lives, and perhaps health, of those whose work, lives and recreation depend on the sea. Ballast Water Steps have already been taken to minimise the marine environment risks of ships emptying ballast water straight into our seas. In May 1998, voluntary guidelines for ballast water were replaced with an Import Health Standard, which requires all ships to exchange their ballast with mid-ocean water.
Most ships nowadays can exchange their ballast water.
However exchange only reduces the risk to a certain extent. Some water from the foreign port always remains in the ballast tanks, so it is 'diluted' foreign water that is discharged in our ports. Extra care is taken to ensure ballast from these places has been exchanged before discharge. Despite the use of anti-fouling paint, unwanted organisms continue to hitch a ride on ships' hulls. The Ministry of Fisheries is hoping to manage the problem of fouled hulls in a similar fashion to its management of ballast water, requiring hulls to be cleaned in a manner that collects all the organisms and disposes of them at land based disposal sites.