Sage said New Zealand has 4000 native species which are considered threatened or at risk of extinction, including 81% of native birds.
The Ahuriri Estuary was chosen to make the announcement as it is a major coastal wetland, with at least 55 species of bird being recorded in the area.
The announcement was made Te Komiti Muriwai o Te Whanga today, the group charged with protecting Ahuriri Estuary.
Sage said biodiversity is vital to New Zealand, as they support human health, wellbeing and the economy.
"Biodiversity supports industries as diverse as farming, film production and tourism and New Zealand's international brand," she said.
Throughout the process, the Department of Conservation will work with other government agencies, local councils and iwi and hapū groups.
"With many of our native species found nowhere else in the world we have an international responsibility to safeguard them for their own sake, and for present and future generations."