Hauraki Gulf: New report depicts what marine area could look like in the year 2173

Scientists have imagined a healthy, thriving Hauraki Gulf 150 years from now - something they say could become reality by acting to save Auckland’s big blue backyard today.

Successive stocktakes have shown a gulf being “pummelled” by human pressure, with the most recent detailing expanding kina barrens, “functionally extinct” crayfish populations in heavily fished areas, and thousands of tonnes of nitrogen flowing in from surrounding farms.

In their own new report, however, the University of Auckland’s professors Simon Thrush and Conrad Pilditch offer a much-rosier alternative picture, set in the year 2173.

It describes large, long-lived species on the seafloor that are recovering well in the outer two-thirds of the gulf, which tourists are exploring with personal submarines and remote autonomous underwater vehicles.

Mangrove, salt marsh and tidal flats have expanded landward as part of a managed retreat response to sea level rise that peaked in 2075, while once-displaced populations of migrating shorebirds have re-established themselves.

The gulf’s water clarity has improved, allowing seagrass beds and kelp beds to expand, and the restoration of shellfish species has reached the point they no longer needed transplanting.

The environment is still suffering from a legacy of pollution, risen seas and more-frequent storm events, but greener urban design and innovations in fishing and land use improvements have eased pressure.

Meanwhile, a growth in shellfish and seaweed aquaculture, iwi-led artisanal scallop fisheries, climate mitigation, eco-tourism and power generation has shifted the gulf to a net consumer of carbon.

This all assumed a raft of measures were taken more than a century before, beginning with new marine protected areas (MPAs) created through the Revitalising the Gulf programme - and a Fisheries Management Plan banning mobile contact bottom fishing, set-netting and purse seining.

In this image, an autonomous underwater drone gathers data in a 2173 Hauraki Gulf. Image / Shaun Lee

Many more interventions and efforts followed, including further MPAs in 2028; a massive scale-up of shellfish restoration in 2029; and a new Marine Protected Areas and Spatial Planning Act in 2030, when the gulf was awarded legal personhood.

By 2080, half of the seafloor was restored, rising to 75 per cent a few decades later.

Thrush said the report, being launched at an event at the university this afternoon, was born from frustration at a lack of action from successive governments.

“Our current focus on the doom and gloom of the past and present has not spurred the game-changing decisions we need to produce a more positive future state,” he said.

While heavily degraded ecosystems like the gulf’s took a long time to turn around, he said the report showed that, with ambition and dedication, it could be done.

“The key is acting now. This has to be a top priority for the incoming Government.”

The report comes weeks after new restrictions were announced for bottom trawling, along with a tripling of the area currently under protection from 6 to 18 per cent.

That involved extending the Cape Rodney-Ōkakari Pt and Whanganui A Hei marine reserves, and creating 12 new “high protection areas” and five new “seafloor protection areas”.