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New Zealand’s top marine issues at a glance

Multiple, cumulative human pressures are causing changes to New Zealand’s oceans, coastal marine habitats, and wildlife – these changes are serious threats to the benefits current and future generations will receive from our marine environment.

The top three issues

Global greenhouse gas emissions are causing ocean acidification and warming

Ocean acidification may cause widespread harm to New Zealand’s marine ecosystems, particularly to marine organisms with carbonate shells like pāua, mussels, and oysters. Ocean warming may affect ocean currents, modify habitats, and expand or reduce the areas where marine species are found, and is a primary cause of rising sea levels. Ocean acidification and warming will continue for generations.

Native marine birds and mammals are threatened with extinction

Most of our marine bird species are threatened with or at risk of extinction, including species of albatrosses, penguins, and herons. More than one-quarter of our marine mammal species are threatened with extinction, including the New Zealand sea lion and species of dolphins and whales. These animals have important roles in marine ecosystems and are tāonga (treasures) to Māori. Their fragile state is due to multiple historic and present-day pressures, although accidental deaths of seabirds and marine mammals from fishing (bycatch) have decreased.

Coastal marine habitats and ecosystems are degraded

Of all marine environments, our coastal ecosystems are under the most pressure from human activities. Pressures interact in complex ways to degrade coastal habitats and ecosystems, and impacts can accumulate over decades. The degradation of coastal habitats undermines their functions in the wider ocean ecosystem and compromises Māori values, commercial activities, and New Zealanders’ recreational enjoyment of coastlines and beaches.


The most important coastal pressures, alongside ocean acidification and climate change impacts, are:

  • excess sedimentation
  • seabed trawling and dredging for fish and shellfish
  • marine pests
  • excess nutrients carried down waterways.

Other coastal pressures include other fishing methods, dumping of dredge spoils, reclamation (infilling of harbours and estuaries for coastal development) and pollution from waste water and plastic debris.

Limitations of this report

As national data on many issues are limited, our findings also draw from scientific literature and expert opinion.

The full ecological impacts of fishing are not clear

Fishing is a highly valued economic, cultural, and recreational activity and one of the most important issues for which we did not have sufficient data. In particular, we were not able to draw firm conclusions about the full ecological impacts of commercial, recreational, and customary fishing on coastal and open ocean ecosystems.