Pests and Diseases
Pacific oyster farming has the potential to introduce or develop problems with oyster diseases or parasites. However, the wider ecological effects from oyster diseases and parasites in high densities of cultured oysters have not been reported, and expert assessment suggests that such risks are negligible.
Oyster farm activities are however a potential vector for transporting diseases and pests around New Zealand. So it is important to ensure that farmed stock comes from a healthy source. In addition, oysters are farmed at relatively high densities, and it is important to minimise the risk of a potential disease or pest outbreak and prevent any spread to wild populations and between existing farms.
Marine farm activities (movement of vessels, gear, stock and spat) are one of the potential vectors for transporting unwanted and exotic marine species to new localities around the country.
Marine farms can also provide ideal habitats for some species, especially biofouling species. There is the potential for marine pests to establish on a marine farm, then multiply and subsequently spread into the surrounding natural environment. The pest may then cause changes to existing communities. Also, extensive biofouling by unwanted pest species could adversely affect the oyster farming operations themselves.
The oyster farming industry has been proactive in developing an environmental code of practice, part of which focuses on the minimisation of the potential for further introduction of pests and diseases.
Also, during a serious disease event (e.g. the occurrence of the biotoxin-producing alga Gymnodinium catenatum), the oyster industry developed management procedures to control oyster transfers between regions. Similarly, some farmers have implemented biosecurity management plans for their farms.
New Zealand oyster farmers must comply with the biosecurity reporting procedures and emergency provisions of the government agency in charge of biosecurity – MAF Biosecurity New Zealand.
