DUNEDIN, Aotearoa New Zealand — At a U.N. meeting in 2015, Aotearoa New Zealand’s then Prime Minister John Key made a major announcement that drew praise from international conservation groups: His administration would turn a swath of waters far larger than the country’s land mass into a marine protected area (MPA). The Kermadec Ocean Sanctuary, planned for New Zealand’s northern waters, would have been one of the largest fully no-take MPAs in the world, but the sanctuary violated Māori fishing rights enshrined decades earlier.