Aotearoa New Zealand has 15 times more sea area than land. The extent of the country’s marine environment, along with its remoteness, make it a global hotspot for marine biodiversity.

Marine habitats are diverse ranging from sheltered inlets, fiords, estuaries, seagrass beds, rimurapa/kelp forests, shellfish beds, extensive sandy coasts through to rocky coasts and reefs and the open ocean.

Of the 12,820 marine species assessed, over half are endemic – they occur nowhere else on the globe, though in reality this figure may be much higher given that many species have yet to be assessed.

State and trends

New Zealand's coastal water quality is degraded in some places. There has been a significant loss of some marine habitats, eg mussel beds and seagrass meadows. Some declines are predicted to continue particularly under climate change scenarios.

However, understanding of the scale of change or loss in marine habitats is incomplete. There is currently no comprehensive picture of New Zealand's marine ecosystem quality.

A few species are showing positive trends towards recovery, but others like the popoto/Māui dolphin are not. Examples of conservation successes include the recovery of some protected species from historical harvesting, eg New Zealand fur seals and southern right whales.

Although only 4% of marine species assessed under the NZ Threat Classification System are Nationally Threatened, some are in more trouble than others. For example, one in three seabirds is threatened with extinction.

What we don't know

While there is good information on the trends in some species, trends in the conservation status of many elements of New Zealand's marine biodiversity are difficult to identify.

This is mostly due to a lack of baseline and/or recent information, and the lack of a nationally coordinated approach to monitoring.

For example:

• Two out of three marine mammals are classified as 'Data Deficient', meaning that there is insufficient information to assign a conservation status.
• Less than 1 in 20 marine invertebrates have been assessed for their conservation status.

There are gaps in knowledge on the impacts of many pressures, including environmental limits around sustainable resource use.

Marine biodiversity pressures

Climate change presents the greatest threat to Aotearoa New Zealand's marine habitats.

However, human activities on the land and in the sea have profound consequences for life in the seas, particularly in the immediate to short term, and in nearshore environments.

• Sedimentation and contaminants are high in some areas along the coast.
• Plastic pollution presents a risk to marine life across all the world's oceans.
• Fishing and its wider impacts including bycatch, can pose a risk to some species and habitats.

The implementation of marine protected areas and other conservation and fisheries management measures are acknowledged as conservation successes for the marine environment.