A waka voyage down the North Island's East Coast sailed through a surprising amount of microplastic pollution - and its leader wants action on the ocean scourge.
Hawke's Bay-based waka Te Matau a Maui was among a fleet of canoes which this month sailed to Wellington for the New Zealand Festival's Waka Odyssey event.
In a first-of-its-kind scientific effort, the ocean-going, twin-hulled, rigged waka horua deployed special nets on the ocean surface to trawl for microplastics several times each day of the journey.
ESR and Canterbury University scientists were now separating out the fragments and testing the types of plastics they were made of.
Microplastics are small particles of plastic, often invisible to the naked eye and measuring less than 5mm.
Still, they pose a grave threat to the planet's oceans, where they can enter the food chain in species like tuna and mackerel, and potentially later cause harm to us.
It's estimated an annual eight million tonnes of plastics enter oceans, where they eventually break down into microplastics.
The problem - worsened by a 20-fold increase in plastic production over the past 50 years - could mean, by 2050, the volume of plastic in oceans outweighs that of even fish.
The new effort, organised with ESR, Algalita South Pacific and research group The 5 Gyres Institute, stood to shed some much-needed light on how much ocean plastic was being contributed by New Zealand.
Waka captain Raihania Tipoki said the quantity of microplastics pulled out of the seas off Napier – about 15 pieces with each 20-minute trawl - had been alarming.
"We are not a big port and we don't have any giant cities in Hawke's Bay, yet there was a significant amount of microplastics in the water."
The group were yet to trawl Wellington Harbour, but they expected to find a large amount of floating waste, ranging from microplastics to bottles and caps.
"We are quite concerned about what we might find."
ESR scientist Olga Pantos, who has been involved in the project, said waka were ideal vessels to carry out slow-speed trawls.
"Research into this area is fairly new to New Zealand and we need to do a lot more testing on a larger scale to see how much plastic is out there, not only in the marine but also freshwater and terrestrial ecosystems, and understand the risks they pose to ecosystems, animals and potentially humans."
It was immensely important to Maori, who felt an obligation through kaitiakitanga, or environmental guardianship, to ensure they weren't taking advantage of nature, Tipoki said.
"We understand that we descend from the land and sea - and that the gods didn't create us.
"A lot of New Zealanders think it's not our problem or it's not our fault, but there are things that we can be doing and if we really want to be environmental leaders we need to be actively promoting change."
New Zealand has moved to ban microbeads, but the wider problem of microplastics couldn't be tackled in the same way.
Current legislation encouraged product stewardship and environmental responsibility at the beginning of a product's life cycle.
Tipoki, who is also marching in the Ban the Bag Hikoi in Wellington on Tuesday, hoped the waka voyage would help toward a new strategy to reduce single use plastics in New Zealand.
It has been estimated Kiwis use around 1.6 billion plastic bags per year, with each only being used for an average 12 minutes before being thrown out.
A Greenpeace-organised petition calling for their ban, which has so far gathered more than 60,000 signatures, is also expected to be presented to conservation and associate environment minister Eugenie Sage on Tuesday.
Actor Sam Neill has joined the campaign by shooting a satirical video with Greenpeace in which he eats a plastic bag, just as turtles do in oceans when mistaking them for jellyfish.