Ōtata is the largest island in the Noises group, a chain of islands, outcrops and rocky reefs in the middle of Tīkapa Moana the Hauraki Gulf. Known as Ngā Poitu o Taramainuku to Māori, the islands and their surrounding waters have provided kaimoana for hundreds of years, with archaeological evidence of occupation prior to the eruption of Rangitoto. Several iwi have claims and interests in the islands and the ocean in this area.
The islands provide a good example of decades-long ecological change in an environmental subjected to multiple stressors. The rocky shelves off Ōtata Island’s east coast have seen the retreat of biodiverse kelp forests and the influx of kina barrens.
The Noises have been privately owned by one family, the Neureuters, since 1933. In 1995, the family formed the Noises Trust and gifted the islands to the Trust, aiming to establish long-term protection for this slice of natural heritage. The Neureuters have partnered with Tāmaki Paenga Hira Auckland Museum and the University of Auckland to advance marine protection around the Noises. Their approach engages mana whenua and has an explicit dual focus on science and mātauranga Māori.
Ōtata Island, one of the islands in The Noises group, located in the Hauraki Gulf.
Kāruhiruhi/pied shags (Phalacrocorax varius) nest in pōhutukawa trees on Ōtata Island.
The unique geography of the islands, combined with their position at the boundary of the inner and outer Gulf where tidal currents mix and flow, supports a diverse range of habitats, including:
- Macroalgae forests,
- Rhodolith beds,
- Shellfish beds, and
- Sponges.
The islands themselves are pest-free and are home to a thriving population of raukawa geckos[1], translocated giant wētā/wētāpunga,[2] and flax snails/pupurangi.[3] They are important breeding sites for several seabird species, including little penguins/kororā,[4] white-faced storm petrels/takahikare[5] and grey-faced petrels/ōi.[6] But seabirds are dependent on the surrounding moana too, and conservation beneath the waves hasn’t kept pace with terrestrial efforts.
One seabird species, the spotted shag/kawau tikitiki,[7] has already abandoned its rocky outposts. Underwater, the scallop beds have been dredged extensively by recreational fishers and the once numerous baitfish have disappeared from the main beach at Ōtata, according to observations by the Neureuter family across several generations.
The causes underlying these changes are complex (see ‘Cumulative effects’ section), but two key factors are:
- Fishing pressures – 0.3% of the Hauraki Gulf is protected in no-take MPAs (see section ‘Managing impacts through protection tools’). Both commercial and recreational fishing are permitted across different areas within the gulf, with restrictions on fishing methods varying across time of the year.[8] According to the State of our Gulf 2020 report, the recreational takes of snapper, kahawai and kingfish are larger than the commercial takes for those species within the Marine Park.[9] The decline in species such as snapper and near-total loss of rock lobsters has been associated with a proliferation of kina and decline of kelp forests. Processes that regulate the distribution of echinoderms are poorly understood[10] so the causal connection is contested.
- Reduction in water quality – Coastal and agricultural developments on the land surrounding the Gulf have led to increasing sedimentation, turbidity and nitrogen loads in the Gulf. Other stressors include plastic pollution.[9]
Cape Rodney-Okakari Point Marine Reserve
Fifty kilometres up the coast, we can see a marine environment protected from some stressors. Aotearoa New Zealand’s oldest marine reserve was gazetted here in 1975, protecting a 5.5 km² patch sometimes known as Goat Island or Leigh Marine Reserve. Here, thick kelp forests shelter an array of reef species such as rock lobsters, snapper and parore/black bream.[11]
Before establishment of the marine reserve, the seafloor was carpeted with rock flat barrens inhabited predominantly by kina. Over-harvesting of predator species such as rock lobster and snapper had resulted in an imbalanced ecosystem. The establishment of the University of Auckland’s Leigh Marine Laboratory in 1962 provided the impetus for an adjacent marine reserve. “They are the controls for the uncontrolled experiment that is happening due to fishing and other humans activities,” wrote Bill Ballantine, the Laboratory’s first scientist.[12]
In the 45 years since, the numbers of snapper and rock lobster have increased. A trophic cascade has ensued with the kina barrens being replaced by regenerating brown algae and diverse seaweed assemblages. Subsequent surveys have found that species diversity and abundance have increased markedly inside the reserve. Rock lobster abundance and size is greater inside the reserve when compared to unprotected sites, but numbers have declined since the mid-90s – likely due to a range of factors, including consistent fishing at the boundaries of the reserve.[13] Although not the primary goal of the reserve, it has also had a positive outcomes for fishers, boosting snapper numbers in the surrounding waters.[14]
Snapper and kelp forest at Cape Rodney-Okakari Point Marine Reserve.
Goat Island at Cape Rodney-Okakari Point Marine Reserve.
Initially, it was envisaged that the marine reserve would serve a primarily scientific purpose in line with the legislation. While it has been invaluable for science conducted at the Leigh Marine Laboratory, it has also become a place for public education, outreach and tourism. An estimated 300,000 people visit the marine reserve every year to snorkel, dive, kayak or ride the glass-bottom boat – experiencing the fish-filled waters and learning about our moana.
Could the Noises’ marine environment recover like Goat Island? It’s likely that stopping fishing would not remediate all the ecological changes witnessed over the past few decades. But the experiences from Cape Rodney-Okakari Point Marine Reserve demonstrate that removing this pressure can go a long way to preserving and restoring marine biodiversity. Ideas for protection of the Noises have been floated: the Sea Change – Tai Timu Tai Pari Hauraki Gulf Marine Spatial Plan proposed a no-take MPA around the Noises, surrounded by a larger Ahu Moana Mana Whenua/community co-management area that applies dynamic management principles.
References and footnotes
[1] Woodworthia maculata.
[2] Deinacrida heteracantha.
[3] Placostylus spp.
[4] Eudyptula minor.
[5] Pelagodroma marina.
[6] Pterodroma macroptera.
[7] Stictocarbo punctatus.
[8] Commercial fishing is only allowed in the inner gulf between 1 April and 30 September. See 4F of the Fisheries (Auckland and Kermadec Areas Commercial Fishing) Regulations 1986.
[9] Hauraki Gulf Forum (2020) State of our Gulf 2020. Hauraki Gulf/Tīkapa Moana/Te Moananui-ā-Toi State of the Environment Report 2020.
[10] Glockner-Fagetti, A. and Phillips, N. E. (2020) Species assemblage and recruitment patterns of echinoderms on shallow rocky reefs in central New Zealand, New Zealand Journal of Marine and Freshwater Research, 54(2), pp. 286–304.
[11] Girella tricuspidata.
[12] Ballantine, B. (2014) Fifty years on: Lessons from marine reserves in New Zealand and principles for a worldwide network, Biological Conservation, 176, pp. 297–307.
[13] eCoast Marine Consulting and Research (2014) Cape Rodney to Okakari Point Marine Reserve and Tāwharanui Marine Reserve Lobster (Jasus edwardsii) Monitoring Programme: 2014 Survey.
[14] Le Port, A. et al. (2017) Temperate marine protected area provides recruitment subsidies to local fisheries, Proceedings of the Royal Society B: Biological Sciences, 284(1865), p. 20171300.