EDITORIAL: Sailing close to ecological collapse in Tikapa Moana / Te Moananui-a-Toi

KATE WATERHOUSE (Chair of AGBET)

“Where are all the birds?” asked my friends, who had sailed up from the Marlborough Sounds via East Cape and the Mercury Islands, to spend some time around Aotea. They had sailed here before and birds and workups were what told them they were nearing the Gulf.

If you haven’t heard of “the sliding baseline” before, don’t worry. You know what it is. A retired commercial fisher speaks about 30 years ago heading out of Leigh into a workup and not finding the end of it until he was nearing Port Fitzroy. That’s his baseline. My sailing friends have another. Mine is watching blue maomao rock fishing and see their flashes of blue all around the coast. You have one and your children have one too, but with each generation what is “normal” and “good” shrinks until we are satisfied with one good work up. But there is nothing normal or good about what is happening in the Gulf right now.

Just after Christmas young environmentalist Riley Hathaway of Young Ocean Explorers, posted excitedly from the  middle of a work up in the Gulf – her first for the summer where the Bryde’s whales showed up. The Gulf has historically been so productive that it supports one  of the world’s only populations of resident Brydes whales. They feed on some of the foundation species of fish and plankton that are produced when waters warm, fed by the magic combination of the East Auckland that spins off the East Australian current and starts flowing down the east coast of Northland. In Spring prevailing westerly winds start to push cool water to the surface, especially on the west coasts of Aotea. It’s a stark contrast between this year and the historic abundance tangata whenua speak of. Even 40 years ago think of how often you would see birds working, and how often you see them now.

Ngati Rehua Ngātiwai ki Aotea are one of very few iwi still able to harvest manu oī, muttonbirds. Yet they have not done so for many years because the grey faced petrels are in such poor condition. Opo Ngawaka has many times expressed his concerns over their food sources being fished out – the krill and small fish that the Brydes whales and predatory fish also rely on. 

Seabirds are the canaries in the mine that is commercial fishing in the Hauraki Gulf Marine Park. Most noticeable on any beach is the collapse of the ubiquitous seagull or Red Billed gulls which used to feed on zooplankton chased to the surface by predatory fish like kahawai and trevally. Their breeding colony on the Mokohinau Islands has  reduced from and estimated 13 000 in the 1950s, to a few hundred pairs.

There are concerns too for kororā/blue penguin, white fronted terns, fluttering shearwaters, all species that rely on small fish and krill. Starving kororā are brought into Karen Walker’s home in Tryphena every summer. But what is leading these birds to starve? It’s the productivity of the Gulf, its capacity to sustain life, which is falling.

You don’t have to look far to find other signs – mussel farmers in Coromandel are reporting that their mussels are smaller and are taking longer to grow – and that there is less spat. Why? It’s likely that phytoplankton, the microscopic creatures mussels feed on are not there in the same volumes as they have been, because the Firth of Thames is warmer and more sediment laden. On top of this, kelp, which may produce up to 40% of phytoplankton, is disappearing fast due to high numbers of kina on reefs, which in turn are out of balance because of, you guessed it, overfishing of their predators, especially snapper and crayfish, but also reef fish.

Many Barrier people will remember Sea Change – the collaborative process to work out a way forward for the Hauraki Gulf Marine Park. More than ten years have passed since focus groups were held on Aotea and elsewhere. Communities were clear: they wanted commercial fishing out of their waters. A goal of giving some form of marine protection to 30% of the park was set. But it had no chance of being implemented. Why? Because the fishing industry in Aotearoa NZ has achieved “regulatory capture”. One definition of this is when regulators act in the interests of industry rather than the sustainability of the fishery, or the life supporting capacity of the ecosystem.

As a child I learned to fish off the wharf at Whitianga, and when the boats were in we got a bag of a dozen scallops for $2 for the BBQ. And who doesn’t love a just cooked scallop with a glass of something cool? Their disappearance from Aotea is not only because too many may have been taken, or because Caulerpa has displaced them. It’s also likely due to overfishing of the so-called Colville Channel “motherbed” at the northwest tip of Coromandel peninsula. Thanks to the tidal flows of Tikapa Moana and Te Moananui a Toi, the spat of that is spread far and wide around the Gulf – into a bay near you. Or it should be. Sadly, that motherbed has been heavily dredged, producing perhaps as little as 5% of spat that it did in 2020. No spat means little renewal of scallops in a bay near you. Without recovery closure, memories of scallops may soon be all we have.

Species after species is being fished far beyond sustainable levels. Of those listed in MPI’s “blue book” not one was fished to its quota in 2023. Most barely reach 30% of their quota. Recently courts have begun to recognise that MPI and DOC must take into account ecosystem effects. But when?

If shellfish like mussels, scallops and horse mussels are not producing spat, then the billions of their eggs that would have fed zooplankton in the Gulf are simply not there. Without the zooplankton forage fish like pilchards and predatory fish like mackerel have nothing to eat, nor do smaller seabirds like terns, prions and shearwaters. Which leads to fewer workups.

If this sliding baseline we are witness to continues, our stories will be the only evidence left of the abundant life supporting food source for 25 species of whales, mantarays, sharks and other megafauna that was once the Hauraki Gulf. Not to mention the incredible fishing.

Te Moananui a Toi will come under increased stress as oceans warm and it needs more resilience not less, to continue to sustain life. It means tangata whenua, communities, fishers and governments must act in its interests so that it can recover.

Yes, people have to eat. But it’s clear that many species such as scallops, crayfish, pāua, mussels, forage fish, like pilchards and mackerel, and probably most other fish species, need a rest.

It’s also clear that stopping fishing some species won’t be enough to change the Hauraki Gulf that our grandchildren will inherit. The ecosystem badly needs a rest too, so that it can be more resilient to invasive species like Caulerpa, and to the pressures of a warming climate. The new High Protection Areas are better than no change but they are not enough. Halting large scale indiscriminate fishing methods in the Marine Park (like trawling, seining and bottom dredging are in everyone’s interests, except quota holders). Restoration of kelp forests can happen through the large-scale removal of kina and by leaving crayfish and big snapper be in a bay near you. Expect increased use of rāhui and other protection tools to get this done.

The birds will show us when the food begins to return to Tikapa Moana / Te Moananui a Toi in the numbers that were once usual. If that’s what we want to leave as a legacy we had better get on with taking less.

References

1. New Zealand Birds Online. Red-billed gull/Tarapunga https://www.nzbirdsonline.org.nz/species/red-billed-gull

2. Rayner M. The Gulf’s Complex Web: Politicians fumble at netting simple solutions. Hauraki Gulf Forum Stories https://gulfjournal.org.nz/2024/10/the-gulfs-complex-web-politicians-fumble-at-netting-simple-solutions/

3. Udy JA, Wing SR, O’Connell-Milne SA & Durante D (2019). Regional differences in supply of organic matter from kelp forests drive trophodynamics of temperate reef fish. Marine Ecology Progress Series 621 https://www.researchgate.net/publication/332825887_Regional_differences_in_supply_of_organic_matter_from_kelp_forests_drive_trophodynamics_of_temperate_reef_fish

4. LegaSea. Fish for the People. Small fish, mighty ecosystem Small fish mighty legacy https://legasea.co.nz/action/campaigns/baitfish-survey/

5. Forest & Bird Media Release. January 2023. Fisheries plan for ailing Hauraki Gulf not enough to restore mauri https://www.forestandbird.org.nz/resources/fisheries-plan-ailing-hauraki-gulf-not-enough-restore-mauri