Fish stocks under pressure, climate change-driven acidification and a rising tide of plastic pollution: we're hearing more about the plight of our oceans. But what can we do about it? As we head to the beach for our first summer swim, Jacob Anderson of the Sir Peter Blake Trust shares five easy things we can do to help protect our precious marine environment.

Do you think of the Hauraki Gulf like you do Fiordland or Tongariro National Park?

Since 2000, the Hauraki Gulf Marine Park has been our first national park of the sea.

An area with more than 50 islands and five marine reserves, the Hauraki Gulf Marine Park is a taonga, or treasure.

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Within the gulf, a hotspot for biodiversity, 22 species of whales and dolphins, and more than 70 seabird species have been recorded.

But increasing pressures from overfishing and pollution have prompted calls for action to restore these magnificent places to the pristine blue oases they once were.

For example, trevally numbers are down 86 per cent, and snapper numbers are down 83 per cent from their historic levels in the Gulf.

The challenge is marine issues throughout New Zealand have not been a priority for local and central governments, and many people have never explored beyond the coast or dipped beneath the surface to see both the richness of New Zealand's marine biodiversity and the degradation occurring.

Our terrestrial (on dry land) bias has meant there is a sense of "ocean blindness"; an inability for most people to see beneath the surface.

As Kiwis, we commonly have a relationship with the ocean that is about extraction or utility -  fishing, harvesting kaimoana and using the water for recreation or transport – without understanding the responsibilities of kaitiakitanga (guardianship and protection).

While we may be a small land-based nation, we have the fourth-largest Exclusive Economic Zone in the world – 93 per cent of New Zealand is underwater.

Within the gulf, a hotspot for biodiversity, more than 22 species of whales and dolphins, and over 70 of the world's seabird species have been recorded. Photo / Auckland Whale and Dolphin Safari
Within the gulf, a hotspot for biodiversity, more than 22 species of whales and dolphins, and over 70 of the world's seabird species have been recorded. Photo / Auckland Whale and Dolphin Safari

To reduce our impact on the ocean and restore these fantastic marine environments, we all have a role to play.

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While you are out enjoying the sea this summer, here are five things you can do to reduce your impact on the ocean.

Fish and eat fish responsibly

Don't treat the catch limit as a target, only catch what you need and keep your catch size legal.

Not all fish populations are in good shape.

If you are eating commercial seafood, refer to the Best Fish Guide to ensure it's sustainably caught.

This resource lists nine "great to eat" seafood choices, including salmon, mussels, pacific oysters and paua (all farmed), albacore and skipjack tuna, rock lobster, cockles and pilchards.

A further 33 are in the "OK to eat" categories.

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Support Marine Protected Areas

Studies report protecting 30 per cent of the world's oceans from human influence will not only be good for conservation, but address challenges regarding overfishing, plastic pollution and climate change.

The Cape Rodney/Okakari Point (Goat Island) Marine Reserve. New Zealand has less than half a percent of our marine environment fully protected, compared to a third of our land. Photo / File
The Cape Rodney/Okakari Point (Goat Island) Marine Reserve. New Zealand has less than half a percent of our marine environment fully protected, compared to a third of our land. Photo / File

The current United Nations target is to protect 10 per cent of the world's oceans by 2020 – a target considered too low to conserve marine ecosystems and sustain fisheries.

Right now, New Zealand has less than half a per cent of our marine environment fully protected, compared with a third of our land.

Well-managed, properly-designed marine reserves with appropriate boundaries can result in restored habitats, help recover fish populations and reduce pollution.

The best thing you can do is write to your local minister, local council or Fisheries Minister Stuart Nash.

Let them know we need more marine reserves to safeguard our marine habitats and ecosystems.

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Reduce carbon emissions

The ocean and atmosphere are strongly linked, and exchange heat and gases all the time through the wind.

The ocean regulates the climate and acts as a heat sink, absorbing 93 per cent of global heat from the atmosphere.

As waters warm and ocean currents change, animals and plants may migrate southward (in the Southern Hemisphere), resulting in modified or lost habitats.

As well as warming waters, as the ocean continues to absorb carbon dioxide, the pH of the surface ocean decreases.

When carbon dioxide dissolves in seawater, carbonic acid forms and the water becomes more acidic. The higher acidity in the ocean inhibits shell growth in marine animals.

As the water becomes more acidic, some organisms will struggle to adapt and could potentially become extinct.

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The best ways to reduce your carbon emissions are to take public transport, cycle or drive electric vehicles, offset or reduce flights, reduce food waste and reduce meat consumption.

Reduce pollution

Based on predicted rates, there will be more plastic than fish in the sea by 2050.

In New Zealand, a major source of marine pollution in our cities comes from urban runoff during storms.

Rainfall picks up plastics, motor oils, heavy metals and other pollutants from roads and drains, and carries them out to sea.

Once ingested, the plastics stay in the animal's gut, and pollutants can build up in animals to toxic levels, resulting in death.

To reduce the risk of plastic going out to sea, you can refuse and reduce plastic use (use reusable bags, refuse plastic packaging, straws and bags, don't buy plastic gimmicks).

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When washing your car, try to let the water pass through soil rather than wash down the drain.

The Hauraki Gulf is under increasing pressure from pollution - as well as over-fishing and other human-driven impacts. Photo / File
The Hauraki Gulf is under increasing pressure from pollution - as well as over-fishing and other human-driven impacts. Photo / File

Deforestation and agriculture have resulted in erosion of soil washing large quantities of sediment into waterways and out to sea.

An example is the sediment accumulation on the tidal flats of the Firth of Thames, which is causing large-scale environmental change.

High volumes of sediment impact coastal and estuarine environments by reducing light levels, burying sea grasses, clogging up filter feeders and reducing feeding success of juvenile fish such as snapper.

To reduce sedimentation and improve water quality, waterways can be protected through riparian planting, fencing and mangrove conservation.

Spread the word

To cure our ocean blindness, we need to be talking about the ocean and the challenges it faces.

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If we want to see healthy fish populations again, it is important we understand what the environments used to look like and what needs to be done to restore them.

If we want to protect the climate, we must protect the ocean.

The longer we wait, the bigger the challenge.