Exotic Caulpera surveys

Logging where and when I have been looking for the exotic Caulerpa species that have been recently introduced to Aoteroa New Zealand.

28 June, Low tide walking, 2hrs. This seagrass meadow near the Half Moon Bay Marina is vulnerable. Good coverage but a drone would be more effective. Checked the high tide line on my return.
11 July, High tide scuba /snorkel 2hrs. This bay is north east of the Kawau Bay incursion. Dive report here.
12 July, Low tide walking, 2hrs. This bay is north of the Kawau Bay incursion. Very calm and I could see a few meters under the water. Checked the high tide line on my return.
25 July. High tide walking 2hrs. Beach cast seaweed on high tide line checked.
26 July. Low & Mid tide walking. Beach cast seaweed on high tide line checked.
26 July. High tide walking. Beach cast seaweed on high tide line checked. This marina is a vector.
23 August, High tide scuba for 30 minutes around rock (swimming fast). Free dived at two other locations in the bay. This bay is north east of the Kawau Bay incursion

New Zealand’s crazy fishing rules

With the government reviewing the Wildlife Act 1953 I got to thinking about our wild fish. The rules are pretty crazy.

I definitely think its time for a review.

Link to high res portrait version of this diagram.

Why I’m supporting the Waiheke Marine Reserve proposal

Here is my submission on the Hākaimangō – Matiatia Marine Reserve (Northwest Waiheke Island) application. Details and submission form here. Feel free to use any or all of this submission yourself and send it to: waihekeproposal@publicvoice.co.nz


There have been decades of korero about marine protection in the Hauraki Gulf / Tīkapa Moana / Te Moananui-ā-Toi. Everyone knows we urgently need more protection but the Governments proposals are too small, experimental, slow and ignore Waiheke Island.

The only concern I have about the Hākaimangō – Matiatia Marine Reserve (Northwest Waiheke Island) application is the lack of published support from iwi authorities. My understanding is that the applicants and the Department of Conservation continue to engage iwi (nine months to date), but while iwi authorities at this stage have not committed their support they are interested in dialogue and importantly they have not opposed the application. Two leading descendants of 19th century Waiheke Ngāti Paoa chiefs, Moana Clarke and Denny Thompson have expressed open support. Iwi politics in the Treaty settlement era are complex and difficult for me as a pakeha to understand. I am concerned about the considerable expectations put on Māori. If we limit our support to co-designed or iwi led marine reserve applications we would be burdening iwi with a responsibility for marine heath they do not seem to be resourced to implement. There are no published concerns about the proposal from iwi. 77% of Māori support 30% marine protection in the Gulf (Hauraki Gulf Forum Poll 2021). I hope that the iwi leaders will put the mauri / lifeforce of the HGMP first and support the application. In the meantime the cautious approach of iwi authorities is no reason not to support the application. If any iwi do have concerns we should take great care to hear and work through those concerns, they have significant rights as mana moana.

UPDATE 28 February. A local iwi body the Ngāti Paoa Trust Board are supporting the application.

16 reasons I’m supporting the Hākaimangō – Matiatia Marine Reserve (Northwest Waiheke Island)

1. We don’t have enough protection. A tiny 0.33% of the Hauraki Gulf Marine Park (HGMP) is fully protected from fishing, the governments Revitalising the Gulf plan will hopefully increase this area to 0.575% by late 2024 (Revitalising the Gulf 2021). The other forms of protection suggested in the plan all involve some kind of fishing. We need places where with intact ecosystems where our taonga and heritage don’t get eaten. The proposed Hākaimangō – Matiatia Marine Reserve is a significant addition at 0.195% of the HGMP. All the proposed protections need to be actioned as soon as possible to reverse the decline of biodiversity and abundance in the HGMP (State of our Gulf 2020). If all the proposals are accepted only 6.7% of the HGMP will be protected from fishing (excluding cable zones which are not designed to protect biodiversity). We will need many more proposals to meet the Hauraki Gulf Forums goal of 30% protected.

2. It’s long term. Rāhui enacted through section 186 of the Fisheries Act only last for two years. This is not the right tool to use to sustain large breeding animals live for more than 50years. Tāmure / Snapper can live to at least 60 years of age (Parsons et. al. 2014).

3. It’s big. For decades scientists have been telling us that our marine reserves are not big enough to protect wildlife from the edge effect. If approved at 2,350 ha Hākaimangō – Matiatia would be the largest marine reserve in the HGMP.

4. It’s in a great spot. The site covers an ecological transition zone between the waters of the inner and outer Gulf. The inner Gulf is slightly cooler, more turbid, shallower, low energy (sheltered by a screen of islands including Waiheke Island) compared to the outer Gulf which is deeper, warmer, clearer and comparatively high energy marine environment. The site was select by marine biologist Dr Tim Haggitt after doing extensive surveys around Waiheke Island in 2015. The area is geologically remarkable for its extensive underwater platforms and terraces, the diversity in physical habitat is reflected in the flora and fauna.

5. There are plants and animals left worth protecting. Functionally extinct species like Kōura / Crayfish (Jasus edwardsii & Jasus verreauxi) are still found in the area so the recovery time here will be faster than other overfished areas of the HGMP.

6. We need more baby fish. It takes thirty six 30cm Tāmure / Snapper to make the same amount of eggs as one 70cm fish (Willis et. al., 2003). This marine reserve would dramatically increase egg production in the HGMP. Marine reserves make a disproportionate (2,330% Tāmure / Snapper in the reserve at Leigh) larvae spillover. Adult Tāmure / Snapper within the reserve at Leigh were estimated to contribute 10.6% of newly settled juveniles to the surrounding 400km2 area, with no decreasing trend up to 40km away (State of our Gulf 2020).

A 40km radius from the centre of the proposed marine reserve.

7. Fishing on the boundary will be awesome. The proposed marine reserve is big enough for people to fish the borders with a clear conscience. Fishing here will be popular with many big fish leaving the area (See Halpern et. al. 2009 on spillover).

8. People want marine reserves. Marine reserve support is strong and getting stronger. On island support for marine protected areas from island residents was 67% with off-island ratepayers at 54% in 2015. A 2021 poll by the Hauraki Gulf Forum shows general support for 30% protection at 77% with only 5% opposition. The poll showed no difference in support from Māori.

9. It’s a great cultural fit. Most people who live on Waiheke Island really care about the environment. Conservation values are strong across the different local communities.

10. It will be great for education. The marine reserve will create much richer outdoor education opportunities for the young and old people of Waiheke and Auckland. Rangitahi in particular will benefit from being able to experience an intact marine ecosystem. Te Matuku Marine Reserve is less suitable for education because the water clarity is dramatically impacted by sediment.

Left: Diver at high tide in the Te Matuku Marine Reserve.
Right: Wheke / Sydeny Octopus at high tide in the proposed marine reserve.
Photos by Shaun Lee.

11. Resilience to climate change. By maximising biodiversity and abundance the marine reserve will protect the HGMP from climate change impacts, particularly heatwaves, invasive species and ocean acidification. Marine reserves are like insurance against uncertainty.

Marine heatwaves are causing local extinctions

12. Improving the economy via commercial fisheries. Juvenile Tāmure / Snapper leaving the Cape Rodney to Okakari Point (Goat Island/Leigh) Marine Reserve boosted the commercial fishery by $NZ 1.49 million per annum (Qu et. al. 2021). Auckland University found 10.6% of juvenile snapper found throughout the Gulf – up to 55 km away were sourced from from this one marine reserve. The researchers found economic benefits to the recreational fishery are even more substantial.  There are other commercially fished species in the area The proposed marine reserve is four times bigger than the Goat Island reserve.

13. A benchmark. No harm marine reserves provide a reference point for assessing the impacts of our activities elsewhere. “As kaitiaki in the broadest sense, we have an obligation to preserve natural examples of marine ecosystems” – State of our Gulf 2020. Data obtained from marine reserve monitoring compliments fisheries information and matauranga Māori to help us understand environmental change.

14. Science. Marine reserves are a natural laboratory. They have contributed massively to our understanding of marine ecology and ecological processes. Many of our leading marine scientist studied and conducted research in marine reserves at Leigh, Tāwharanui, Hahei and elsewhere. Of course the Marine Reserves Act expressly recognises the scientific importance of marine reserves. Scientific research is an over-riding priority in the Act,

15. Tourism benefits. The marine reserve will add to the growing ecotourism opportunities on Waiheke Island. It complements the $10.9 million dollar investment in Predator Free Waiheke (Predator Free 2050 Limited 2021) which has a vision to become the world’s largest predator-free urban island. The marine reserve will be much cheaper to create and maintain and will deliver a mountains to the sea nature experience.

16. Return on investment. The Cape Rodney to Okakari Point Marine Reserve (Goat Island) generated $18.6 million for the local economy in 2008 at a cost of about $70,000 for the Department of Conservation (State of our Gulf 2020).

The Hauraki Gulf / Tīkapa Moana / Te Moananui-ā-Toi can not afford to have this application sit on a shelf waiting for stronger political leaders. Please start the process of creating the Hākaimangō – Matiatia Marine Reserve and healing the wider area as soon as possible.


References

Hākaimangō – Matiatia Marine Reserve (Northwest Waiheke Island) https://friendsofhaurakigulf.nz/

Hauraki Gulf Forum Poll 2021. https://gulfjournal.org.nz/2021/11/results-of-hauraki-gulf-poll/

Parsons DM, Sim-Smith CJ, Cryer M, Francis MP, Hartill B, Jones EG, Port A Le, Lowe M, McKenzie J, Morrison M, Paul LJ, Radford C, Ross PM, Spong KT, Trnski T, Usmar N, Walsh C & Zeldis J. (2014). Snapper (Chrysophrys auratus): a review of life history and key vulnerabilities in New Zealand, New Zealand Journal of Marine and Freshwater Research, 48:2, 256-283, https://doi.org/10.1080/00288330.2014.892013

Predator Free 2050 Limited 2021. Annual Report 2021 https://pf2050.co.nz/predator-free-2050-limited/

Revitalising the Gulf 2021 https://www.doc.govt.nz/our-work/sea-change-hauraki-gulf-marine-spatial-plan/

State of our Gulf 2020 https://gulfjournal.org.nz/wp-content/uploads/2020/02/State-of-our-Gulf-2020.pdf

Qu et. al. (2021). Zoe Qu, Simon Thrush, Darren Parsons, Nicolas Lewis. Economic valuation of the snapper recruitment effect from a well-established temperate no-take marine reserve on adjacent fisheries. Marine Policy. Volume 134. https://doi.org/10.1016/j.marpol.2021.104792

Willis, T.J., Millar, R.B. and Babcock, R.C. (2003), Protection of exploited fish in temperate regions: high density and biomass of snapper Pagrus auratus (Sparidae) in northern New Zealand marine reserves. Journal of Applied Ecology, 40: 214-227. https://doi.org/10.1046/j.1365-2664.2003.00775.x

Halpern, B., Lester, S., & Kellner, J. (2009). Spillover from marine reserves and the replenishment of fished stocks. Environmental Conservation, 36(4), 268-276. https://doi.org/10.1017/S0376892910000032

Where are all the fish in the Hauraki Gulf?

The most barbaric way to answer this question would be to drag a giant net around and count what you kill but you’re not allowed to do that in the inner Gulf where trawling is restricted… unless you have a research permit from Fisheries New Zealand (FNZ). Despite calls to stop bottom trawling in the Hauraki Gulf Marine Park (HGMP) (Sea Change 2017 & Hauraki Gulf Forum 2021) FNZ have started doing these trawls regularly, they justify the trawls are required to gather information on the Tāmure / Snapper population. They haven’t done research trawls like this since the Hauraki Gulf Marine Park Act came into effect in the year 2000 (NIWA 2019). In areas where trawling is restricted (c25% of the HGMP), the study was like bulldozing a regenerating forest to count the birds. A disgraceful act on private land let alone a national park.

How much seafloor was scraped?

The nets are massive, wider than a rugby field. FNZ were just interested in killing demersal fish (goundfish), they dragged theses massive nets along the seafloor smashing down anything that lives there and creating giant sediment plumes that contribute to climate change. In areas that have been closed to trawling for decades there are patches of horse mussel beds, sponge gardens and tubeworm mounds and other habitats regenerating after decades of abuse from heavy machinery. You can read about them in the report (NZFAR 2021) where they are described as ‘foul’ a horrible word which suggests there is something ugly about these beautiful benthic epifauna that are working hard (day and night) to clean up our pollution (they are nearly all filter feeding animals). In defense of FNZ they did try and avoid areas with a lot of immobile sea life but they failed so badly that they had to stop trawling on several occasions, this shows that a) the seafloor is recovering and b) echosound is no good for measuring trawling impact on benthic life.

Although the percent of trawled seafloor was small (less than 1% of the study area) the areas bottom trawled were huge:

39 rugby fields between Shakespear Regional Park and Rangitoto IslandStratum 1386
54 rugby fields of the inner Firth of ThamesStratum 1887
68 rugby fields of the mid Firth of ThamesStratum 1268
88 rugby fields in a west-east band North of Waiheke IslandStratum 2229
59 rugby fields around the western side of Waiheke IslandStratum 1149
41 rugby fields north of Whangaparāoa PeninsulaStratum 1284
40 rugby fields northwest CoromandelStratum 9292
60 rugby fields south of the line dividing the inner gulfStratum 1219
59 rugby fields from Bream Bay to MangawhaiStratum 1449
49 rugby fields between Aotea / Great Barrier Island and Ahuahu / Great Mercury IslandStratum COLV
77 rugby fields north of the line dividing the inner gulfStratum LITB

A total of 615 rugby fields, 381 of those fields had not been physically impacted by trawling for decades. The trawls were about 1/10th as long as a commercial trawl which may impact 1–10 km2 (MacDiarmid 2012). This is largely due to the horrific sediment plumes they create, especially on mud which most of the trawls in restricted areas were. This means the total trawl distance of 53.35km could have impacted up to 40km2 (6,349 rugby fields) of seafloor – choking animals and smothering plants.

The research trawler Kaharoa. Photo by Dave Allen (NIWA).
The research trawler Kaharoa. Photo by Dave Allen (NIWA).

So where were all the fish?

The average catch weight per trawling station in restricted areas was 500% higher than areas where bottom trawling is not restricted (1,033kgs vs only 171kgs). That’s a huge difference, the commercial fishers pulling up the nets must have been blown away with the haul! There was no significant difference in the size of the trawls but there was a big difference in depth. Trawls in trawling restricted areas averaged about half the depth (23m) of those in regularly trawled areas (47m). So are the fish benefiting more from trawling restrictions or depth?

Figure 1. Catch weight per station by depth in trawled areas. The red line predicts catch weight going down in deeper areas.
Figure 2. Catch weight per station by depth in areas where trawling is restricted. The red line predicts catch weight going down in deeper areas.

As you can see from Figure 1 & 2 there is no correlation between depth and catch weight (red line vs data). There could be many other factors involved (FNZ seemed to deliberately avoid trawling on sand in the inner Gulf so we can not directly compare substrates), but the 500% increase in catch weight in areas protected from trawling shows that protecting the seafloor from bottom trawling dramatically increases the amount of fish that live on the seafloor.

The survey is good news for recreational fishers who shouldn’t leave the inner Gulf to catch more Tāmure / Snapper. If you’re a fisher who wants to know where demersal fish are in the Gulf I recommend you read the report (NZFAR 2021). If you want to know which trawling station got the highest catch… I’m not telling! You will have to ask FNZ, you can send them an OIA request Official.InformationAct@mpi.govt.nz why don’t you tell them to stay out of the restricted areas and stop bottom impact fishing at the same time 😀

What happened to all the fish?

The total weight of fish (mostly Tāmure / Snapper) landed was 41,759 kilograms! 80% of the dead fish was sold for $128,449.35 which seems like a lot but with Tāmure at $20-$30 per kg at the supermarket they could have made more than one million dollars selling it direct to consumers. Of the total revenue from the two years of survey approximately 73% ($93,634.47) was absorbed in operation costs of the research vessel to process the catch. The remaining balance ($34,814.88) was returned to the Ministry of Primary Industry. That means even selling the dead fish dirt cheap the surveys make a profit for the Government. The self issued scientific permit to trawl in restricted areas is more profitable than some whaling trips the Japanese government justifies as science.

What else did they haul up?

I was surprised to see invasive species like Mediterranean fanworm (Sabella spallanzanii) turning up in the catch. They are very skinny and should fly through the nets. There must have been very dense beds in places. It was disappointing to hear from my Official Information Act request that Biosecurity New Zealand was not informed of which stations had high numbers of the Unwanted Organism. The lack of interagency communication (even with MPI) sucks but the double standard is worse. When restoring the seafloor from fishing damage the Mussel Reef Restoration Trust must notify an MPI technical officer if it accidentally releases an Unwanted Organism (a legal requirement of moving Unwanted Organisms under the Biosecurity Act 1993). Bottom trawlers however can move them around the Gulf with no regard to Biosecurity. This shows how Biosecurity NZ favours industry over community groups.

Will they do it again?

The surveys continue despite FNZ no longer having a public license to bottom trawl the HGMP. There is 84% public opposition to fishing methods that impact the seafloor (Hauraki Gulf Forum 2021). Most fisheries scientists take samples 100’s of times smaller or use baited underwater video cameras to count and measure fish. FNZ definitely don’t have a social license to trawl in restricted areas but they are ploughing on. Because I make a living doing science communication its not in my interests to criticise the research survey but I had to because I think what they are doing is wrong.

Notes

I included trawl stations in areas where Danish seining is allowed and trawling is restricted in the restricted totals. The three stations had an average catch weight that lowered the average restricted catch weight and increased the average catch depth.

References

Sea Change 2017. Sea Change – Tai Timu Tai Pari Marine Spatial Plan. Hauraki Gulf Forum, Ministry for Primary Industries, Department of Conservation, Waikato Regional Council, Auckland Council. 2017.

MacDiarmid 2012. Assessment of anthropogenic threats to New Zealand marine habitats. A. MacDiarmid. New Zealand Aquatic Environment and Biodiversity Report No. 93 2012

NZFAR 2021. New Zealand Fisheries Assessment Report 2021/08. Trawl surveys of the Hauraki Gulf and Bay of Plenty in 2019 and 2020 to estimate the abundance of juvenile snapper. 2021. https://fs.fish.govt.nz/Doc/24856/FAR-2021-08-Hauraki-Gulf-2019-Bay-Of-Plenty-2020-Trawl-Surveys-4125.pdf.ashx

Hauraki Gulf Forum 2021. Results of Hauraki Gulf Poll by Alex Rogers. The Gulf Journal

https://gulfjournal.org.nz/2021/11/results-of-hauraki-gulf-poll/ Accessed December 2021

NIWA 2019. NIWA to survey young snapper in Hauraki Gulf. https://niwa.co.nz/news/niwa-to-survey-young-snapper-in-hauraki-gulf Accessed December 2021.

Feeding our forests

I have begun doing some work with the Northern New Zealand Seabird Trust who invited me to come and help them with some field work on the Poor Knights Islands. My father had visited the Islands when he worked for DOC in the 1990’s, his stories about the reptile abundance really inspired me to do restoration work, and I jumped at the opportunity to go.

Landing on the Island is notoriously difficult and our first shot at it was delayed, we had to go back to Auckland to wait for better weather. The islands are surrounded by steep cliffs that made European habitation impractical, Māori left the area in the 1820’s. This means the island I visited has never had introduced mammals, not even kiore! I spent days cleaning my gear to get through the biosecurity requirements which are incredibly strict for good reason.

I have explored a few predator free islands including Hauturu / Little Barrier Island which has been described as New Zealand’s most intact ecosystem. However it was only cleared of rats in 2004. When I am photographing invertebrates at night in mainland sanctuaries or forests with predator control (like Tāwharanui Regional Park or parts of the Waitakere Ranges) I see one reptile every eight hours or so. On Hauturu / Little Barrier Island I see them every 20 minutes, but on the Poor Knights it was every two minutes! Bushbird numbers were lower than other islands, I expect this is because reptiles and birds compete over prey species. I wonder if reptile numbers on other islands might be slower to recover because they are preyed on by bushbirds. I reckon that the Poor Knights total reptile and bushbird biomass is much greater than the restored islands I have visited. One reason for this is that reptiles use less energy to hunt than bushbirds but the other reason might be because it has more seabirds.

While walking through the bush at night I would sometimes hear a crashing in the canopy followed by a soft thump on the ground. In an incredible navigational feat the seabirds somehow land only meters from their burrows. At night I heard Buller’s shearwater, grey-faced petrel, little penguins and diving petrel (fairy prion finish breeding in February). While monitoring birds at night I was showered with dirt by a Buller’s shearwater who was digging out a burrow. In my short time on the island I saw cave weta and three species of reptile using the burrows. Like a rock forest the burrows add another layer of habitat to the ecosystem. It was incredibly touching to see the care and compassion the researchers had for some of the chicks who were starving while waiting for their parents who often have to travel hundreds of kilometres to find enough food. The chicks who don’t make it die in their burrows and are eaten by many invertebrates, the invertebrates in turn become reptile or bushbird food. The soil on the island looked thick and rich, when it rains nutrients are bought down into the small but famous marine reserve which is teaming with life.

I was only on the island for three nights but I was very fortunate to experience a pristine ridge to reef ecosystem. Seabirds are incredible ecosystem engineers who were an integral part of New Zealand’s inland forests for millions of years. Communities are making small efforts to bring seabirds back to predator free island and mainland sites with no control over seabird food sources. If we really want intact ecosystems we will have to make sure our oceans have enough food for seabirds to feed our forests.

What’s at the bottom of Jones Bay Lagoon?

I have driven past Jones Bay Lagoon many times and always wondered what’s down there. It was dredged for shingle from about 1870-1950 and would have had a stony seafloor like Jones Bay. I had heard that the mining might have made the lagoon 20 meters deep. Altho I knew there was sediment around the edges I imagined it was quite stable as most of the receiving catchment has been reforested including the regions best example of a wetland (albeit a small one).

Areas explored in green

I made a few transects at high tide. There was no noticeable current and the visibility above 4m was about 3m. However nearing the 5m mark the visibility dropped to .2m and was not much fun. I was able to easily plunge my hand into the seafloor about 30cm deep before it got uncomfortably sticky and heavy, the mud was very dark grey. The deepest spot I found was 7.5m with most of the lagoon at 5m. The contour of the seafloor varied and did not make sense with the odd ridge appearing in unexpected places.

I saw several fish including, a school of spotty, many yellow-eyed mullet in the shallows, a few snapper, and what I think were estuarine triplefin.

No Fishing. Marine pests found in this lagoon.

The biggest surprise however was the no fishing signs erected by Auckland Council. I was pleased to see them as it has always felt wrong to allow killing of native species in the Regional Park, which is supposed to be a safe place for nature. It was also a surprise given my recent request for Council to start managing the effects of fishing. This sign however is only here to manage a marine pest called Eudistoma or the Australian droplet tunicate.

Eudistoma are the little white things, the stalks belong to Mediterranean fanworm.

I knew that Eudistoma had reached the park because I was alerted by a member of the public on the 4th of February. It was no surprise as they were spreading fast and I documented dense areas of them on the other side of Kawau Bay in February 2019. The lagoon also had large numbers of Mediterranean fanworm (another marine pest) which interestingly often hosted native pleated sea squirts which I have not noticed on fanworm elsewhere. Mediterranean fanworm and Eudistoma are both present in the ocean, meters from the mouth of the lagoon. There was one small cockle bed in a sandy area and several areas with pacific oysters in the shallows. I have asked Auckland Council to comment on the closure which happened in spring 2020.

The Coastal Marine Area boundary on Unitary Plan viewer

Response from Auckland Council below.

The coastal marine boundary follows the South Coast/Jones Bay foreshore of Tāwharanui Regional Park, thus the lagoon is within the regional park, or at very least the land around it.

Fishing here is inconsistent with the general Regional Parks Management Plan to not take flora and fauna. The unwanted organism would be a threat to the Tāwharanui Marine Reserve. The regional parkland provides land based access to the periphery of the reserve and there is a real risk of transfer of organism in viable state on wet fishing gear between the two sites. The identification of the tunicate prompted a management response.

A short photogrammetric transect (4-5m)
Another slightly longer one, the fanworm are not as clear as I had hoped, I need to get much better at over-laping the frames.

I am making sure to decontaminate my dive gear, and I do not recommend the area for diving, in fact I think it might be with looking at the sediment inputs and, if they are low, considering the site for mussel bed restoration.

Indigenous biodiversity

I have 1,612 verified observations on iNaturalist between Auckland and Whangarei documenting 552 species (mostly invertebrates) covering forest, freshwater, intertidal and marine habitats. I don’t take many photographs of plants. Of these observation 96 or 17% of species were introduced. Here is a break down showing areas where I have found more or less introduced species:

Hauturu Aotea Tawharanui East Auckland Waitakeres Hunua Ranges Rangitoto / Motutapu / Motuihe Motukorea Mungatapere
Observations 206 149 141 197 77 94 71 33 159
Species 86 84 86 120 57 64 52 25 83
Introduced 6 12 8 35 1 4 11 4 9
Percent introduced 7 14 9 29 2 6 21 16 11

I expected the restored and protected islands in the Hauraki Gulf to have a smaller percent of introduced species. I think the high number of introduced species (compared to the Waitakeres and the Hunua Ranges) reflects the islands farmed history with islands like Motukorea and Motutapu still dominated by kikuyu. The larger and older the forest the more indigenous biodiversity.