 In New Zealand, the Pacific oyster was unintentionally introduced in the 1950s, most likely through ballast water and from the hulls of ships.Aquaculture farmers at the time noticed the Pacific oyster outcompeted the endemic species, the Sydney rock oyster ("Saccostrea glomerata"), which naturally occurs in intertidal areas in the North Island.Early experiments in rock oyster cultivation procedures attached spat to cement-covered sticks and laid them down in racks.