 This presents major issues for virus management of open-water shellfish farms, as shellfish like the Pacific oyster have been found to contain norovirus strains which can be harmful to humans.Globally, noroviruses are the most common cause of nonbacterial gastroenteritis, and are introduced into the water column by faecal matter, either from sewage discharge or land runoff from nearby farmland.Pacific oysters, like other shellfish, are able to remove heavy metals, such as zinc and copper, as well as biotoxins (microscopic toxic phytoplankton), from the surrounding water.