Aerial view of Rotoroa Island. Overfishing and destruction of the seabed have seen some fish species plummet more than 80 per cent on historical numbers in Hauraki Gulf. Photo / Natalie Slade
A proposal to protect at least 20 per cent of the 1.2 million hectare Hauraki Gulf Marine Park has sparked debate from all sides. In a two-part series Michael Neilson takes a look at worrying state of Auckland's big blue backyard, and plans to restore it. Today: The state of the gulf.
Moana Tamaariki-Pohe fondly recalls collecting pipi and tuangi (cockles) off the shore at Okahu Bay as a child during the 1970s and, with friends and family, cooking them up on the beach.
She remembers paddling out into the bay, and fishing for flounder.
Her father, the late Tamaiti Tamaraaki, would tell stories of the even more "plentiful" kaimoana of his childhood, of mussels and pipi all across the bay, and even snapper.
With his father he'd go on expeditions out into Tīkapa Moana, the Hauraki Gulf, to Rangitoto, down to Kaiaua, for days at a time, living off what they could catch, because they could always catch something.
Now the bay, the kāpata kai (food cupboard) of Tamaariki-Pohe's hapū Ngāti Whātua Ōrākei for generations, is largely a marine desert.
Nobody collects shellfish there anymore, because there are none large enough to eat, and also because any collected would make one severely ill.
A sewer began discharging effluent into the bay in 1914, and while now closed up it still overflows in major storms.
But it is the heavy metal run-off from traffic along Tāmaki Dr, built atop the sewer pipe, Tamaariki-Pohe said was really killing the sea life. The zinc and copper was adding to the polluted waters, and layers of sediment below suffocating shellfish and clogging the seafloor.
"The whole ecosystem has changed, and consequently whānau have lost their connection with the bay," said Tamaariki-Pohe, who advocates for the marine environment as deputy chair and tāngata whenua representative on the Hauraki Gulf Forum.
The story of Okahu Bay is not too dissimilar to scores of bays around the gulf.
Many older Aucklanders will recall sandy inner city bays, and collecting shellfish during their childhoods.
Over the years sediment has flushed into the gulf after vegetation removal and various land developments, meaning most spots are now only swimmable on the high tide, unless bathers want to wade through thick mud, with but a thin section of sand above the shoreline.
Further out into the gulf the story is just as dire.
While recreational fishers still report catching a feed and commercial fishers a profit, the numbers and the science say the future is bleak.
Overfishing and destruction of the seabed have seen some fish species plummet more than 80 per cent on historical numbers.
There have been concerns for decades, with the 1.2 million hectare Hauraki Gulf Marine Park established in 2000, and the Hauraki Gulf Forum - made up for tāngata whenua, council and government representatives - established alongside it to promote integrated management from all sides.
The forum puts out a state of the gulf report every three years, each as bleak as the last.
The latest report, the State of Our Gulf 2017, showed trevally numbers had plummeted 86 per cent from their historic levels, snapper 83 per cent, and sharks - a key part of the ecosystem - 86 per cent.
It is estimated around 880,000 tonnes of snapper - the most important fish species in the gulf ecosystem - have been extracted from the Hauraki Gulf over 700 years of fishing, with 50 per cent of this in the past 100 years.
Crayfish numbers had also plummeted to about 20 per cent of their 1945 levels.
The report also highlighted how interrelated the marine environment was - remove one aspect from the ecosystem and the balance tips out of kilter.
The bed of the gulf was once covered in sub-tidal seagrass beds, mussel beds and other biogenic habitats, such as sponge gardens, that provided sanctuaries for juvenile fish.
But decades of destructive trawling fishing methods have not only helped deplete fishing biomass to less than half the level in 1925, but along with dredging have destroyed those seabeds, leaving vast sections of the seafloor wastelands.
The decline of crayfish is all the more concerning as mature crayfish play a crucial role in reef communities, where they prey on kina and keep their populations under control.
Kina eat kelp and other algae, and when they are released from predation - snapper are also a key predator - they multiply and can strip the kelp forests to bare rock, depriving a diverse range of other kelp-dwelling species of a habitat.
Fishing charter operator Eugen Debruyn had seen this with his own eyes.
He has operated his vessel the Sea Genie in the gulf for about 25 years, and has seen areas around the Noises Islands become "barren", with only spiky, malnourished kina making the once-flourishing seafloor home.
"It is concerning because those kelp forests provide a key habitat for juvenile fish."
Overall he said people were still catching good numbers of fish, but he thought that could coincide with improved technology.
"People are more efficient these days with technology, and I think we are also all simply fishing better."
His main target was snapper, and while there were still schools around, he had noticed a steady decline in mature fish, concerningly the ones that make all the babies.
"I definitely support greater protections. Those reserves provide safe places for the mature fish. But any restrictions on recreational fishers need to be in balance with measures on commercial fishing. There is no place for indiscriminate and destructive fishing methods, like trawling and gill netting, anywhere in the gulf."
The inner Hauraki Gulf was closed to commercial trawling and seining (with vertical fishing nets), and some 90 per cent of the fish taken in that areas was by recreational fishers.
Commercial long-line fisher Laurie Beamish said he still perceived the gulf as holding a "healthy" fish population, including his target species snapper.
He saw long-line fishing as the most sustainable commercial fishing method.
From his perspective, the biggest pressures on the gulf were from sedimentation and run-off, and overfishing of species closer to shore.
Umupuia Beach, near Clevedon, was once a safe haven for shellfish.
When the ancestors of the area's Ngāi Tai iwi arrived there, they stepped from their waka onto a seabed thick with scallops, pipi and cockles.
But much of it had now disappeared, due to a combination of environmental effects, such as siltation, but more concerningly to people taking heavy amounts, Beamish said.
"At one point people were taking thousands at a time, it was getting pretty bad."
As tuangi numbers continued to dwindle, locals began monitoring them and found over 10 years they had dropped to just 10 per cent of what they had started with.
They introduced a rāhui, a temporary prohibition, on collecting shellfish in the area eight years ago, and had seen positive results.
Beamish was supportive of using rāhui, as had been done by Māori for generations, throughout the gulf to temporarirly retire areas to allow them to bounce back, as opposed to marine reserves for perpetuity.
"We see that as a potential form of protection, a rolling system of rāhui, and nuanced rules for when the abundance returns.
"It is our duty, as kaitiaki, to enhance the gulf for future generations."
Seabirds in the gulf are also in a precarious position.
The gulf is an important habitat for the New Zealand fairy tern – our most endangered species – with just 40 individuals and nine breeding pairs estimated to remain.
The nationally vulnerable black petrel is the seabird most at risk from commercial fishing activity, with an estimated 392 birds captured in 2013-2014. Of them, over 100 were captured by the north-eastern snapper longline fishery.
Numbers of the flesh-footed shearwater population – the most common species incidentally captured by the north-eastern snapper longline fishery - has also been rapidly declining from 50,000-100,000 pairs estimated in 1984 to less than 12,000 pairs currently.
The 2017 report found cumulative pressures on the sea were mounting, as human and commercial pressures ramped up.
Auckland's population had boomed over the past decade, increasing by almost a quarter of a million people between 2006 and 2016, and tipped to pass the 2 million mark within 15 years.
Sewage already regularly overflowed from Auckland's wastewater reticulation system into the gulf's waterways, and stormwater outflows also remained a problem, especially in older urban areas.
Between 2014 and 2016, staff from the Watercare Clean-up Trust spent around 6000 hours on clean-up activities, and together with a host of volunteers, removed around 882,000m3 marine litter from the coast.
University of Auckland Professor Simon Thrush, who heads the Institute of Marine Science, said there had been few improvements to the state of the gulf in recent years.
"We've seen growing evidence of the impact of sedimentation in smothering shellfish and habitat, no changes in nutrient loads entering the Firth of Thames, various changes associated with the climate, and are not seeing any changes in terms of the broad issues around overfishing."
Just 0.3 per cent of the gulf was protected as "no take" marine reserves at six locations.
Thrush said even that small area had a huge impact on fish stocks.
"We have been able to document the spillover from the Goat Island marine reserve and found 10 per cent of fish down the coast to Whangaparaoa have parentage from that tiny area."
The best science showed 30 per cent of an area needed to be protected to support recovery and resilience of marine ecosystems.
"It is not just about making more snapper to catch, but ensures we can restore the biodiversity and mauri of the gulf by having a larger proportion protected."
Thrush was also supportive of proposals to restore reefs and shellfish beds.
"There has been a grand loss of very important shellfish species over time, to the effect a large proportion of the seafloor is not working properly."
Mussels once covered some 500 sq km of the Hauraki Gulf and Firth of Thames. It was estimated they could filter the water of the Firth in a day.
Thrush said most of those beds were dredged out in the 1950s and 1960s and never recovered. Closer to shore sedimentation was essentially suffocating shellfish.
High sediment levels, caused by the removal of vegetation from the mainland and various land uses, affected most of the gulf, Thrush said.
High profile spots included at Oakura, where a major housing development was taking place, and the Firth of Thames, impacted by generations of forestry and farming.
But even bays around Auckland city had seen dramatic changes, some in just a few decades.
"A lot of the bays around the gulf would have been sandy beaches. I live at Greenhithe and have seen photos from the 1940s and 1950s of people down at the beach, which looks nothing like it does now, a small strip of sand leading to a complete expanse of mud."
Thrush said it was not only the sediment but how that interacted with fish and shellfish habitat, and nutrients coming off the land.
"That is why restoring areas is great, but it needs to be part of a bigger package."
In the next article of the two-part series we take a look into the Sea Change marine spatial plan, developed over four years and launched in 2016 but with little progress since, and other proposals to turn the state of the gulf around.
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