A marine reserve is an area of the sea that has legal protection against fishing or development. This is to be distinguished from a marine park, but there is some overlap in usage. As of April 2008 there are no high seas marine reserves, but Greenpeace is campaigning for the "doughnut holes" of the western pacific to be declared as marine reserves. They are campaigning for 40 percent of the world’s oceans to be protected as marine reserves. Although less than 1% of the world’s oceans have been set aside in marine reserves. As of 2010, scientists have studied more than 150 marine reserves in at least 61 countries around the world and monitored biological changes inside the reserves. The number of species in each study ranged from 1 to 250 and the reserves ranged in size from 0.006 to 800 square kilometers (0.002 to 310 square miles).
New Zealand currently has 34 marine reserves spread around the North and South Islands and two other outlying islands. These are 'no take' areas where all forms of exploitation are prohibited. Marine reserves are administered by the Department of Conservation. New Zealand's marine environment is more than 15 times larger than its terrestrial area, however only a small portion of it is protected.