Category: Restoration

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The sand is alive

Feather duster tubeworm-Bream Bay-Photo by Shaun Lee

They often tell us that the seafloor is a wasteland. To the naked eye, or through the lens of those looking to profit from it, the vast stretches of sand off our coasts are described as “biological deserts.” But yesterday, diving in the waters of Bream Bay, I saw something else.

I was invited to join a group of marine scientists for a recreational survey in an area currently proposed for a sand mine. What we found wasn’t a desert—it was a nursery, a sanctuary, and a testament to the resilience of nature when we simply give it the space to breathe.

Signs of recovery

Our first dive took us to a spot where previous “dropcam” footage had hinted at life. As we descended, the reality exceeded our expectations. There were so tipa / scallops, everything from tiny juveniles to full-grown adults. Since this area was closed to scallop dredging on October 27, 2022, the ecosystem has begun to knit itself back together. In a world where we often hear only of environmental decline, seeing this rapid recovery was electric. As we surfaced, the lead marine biologist couldn’t hide his excitement: “Best dive ever!”

Tipa / scallop Bream Bay. Photo by Shaun Lee.
Tipa / scallops in a proposed sand mine in Bream Bay. Photo by Shaun Lee.

The moving seafloor

On our second dive, we followed a fish finder signal to a new spot. As I photographed the sand using my macro lens, I realised the sand was alive. The density of tubeworms was so high that the entire seafloor seemed to wriggle with life. These small creatures stabilise the sediment, filter feed, are attachment structures for juvenile scallops and food for fish.

A young sponge (lophon minor) growing in a tubeworm field in a proposed sand mine in Bream Bay. Photo by Shaun Lee.

Grab samples

Emptying the grab sample. Photo by Shaun Lee.

In between dives we used a grab sampler to look at the infauna, it was cool to see the little shellfish living in the sand but the highlight for me were the larger wiggling polychaete worms which I don’t often see.

An even better dive

At the end of the planned transect we discovered a low, flat outcrop of soft, peaty rock. It looked unassuming at first, but it was home to something I never expected to see in my lifetime.

Tucked into this small shelter was a huge pod of over 40 large packhorse rock lobsters. To find one or two of these creatures is rare, as they have been heavily overfished for decades. To see a pod of forty—mostly large males congregating together—was breathtaking. Sharing that space with them were juvenile and adult blue cod, goatfish, juvenile snapper and tiny larval fish.

Packhorse rock lobster in a proposed sand mine in Bream Bay. Photo by Shaun Lee.

This area is not only protected from seasonal scallop dredging since 27th of October 2022, but has been protected from bottom trawling for more than 40 years.

Memory in the water

Packhorse lobsters are known to navigate using the Earth’s magnetic field. Watching them as they traced their feelers over my face and shoulders I couldn’t help but wonder: how did they find this tiny, specific patch of safety in a vast ocean? Is it possible that the memory of these safe havens is passed down through generations?

If we allow sand mining to tear up this seafloor, we aren’t just removing “sand.” We are destroying navigational landmarks, generational homes, and a vital link in the marine food chain.

Blue cod in a proposed sand mine in Bream Bay. Photo by Shaun Lee.

Nothing there

There is a profound disconnect between what the scientists showed me and what industry describes. When pushing for extraction permits, proponents often downplay the biological value of the site. For instance, Callum McCallum, Managing Director of McCallum Bros Ltd, has previously justified mining by stating:

“It’s a very high-energy, mobile environment. To the naked eye, there is nothing there.”

After four surveys in this area, I can say with certainty: there is something there. Every time I go down, I find something more precious, more rare, and more worth saving.

We don’t need to “extract” value from Bream Bay. The seeds are already there, living and breathing beneath the waves. We just need to be quiet enough to let it recover.

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Restoring Motukorea’s Forests with Feral Pigeons

Taupata / Coprosma repens regenerating on Motukorea

Motukorea / Browns Island is a visual icon of the Hauraki Gulf, but beneath its green slopes lies a history of heavy modification. Farmed for the better part of the last century, the island’s terrestrial habitats are now dominated by Kikuyu grass—a thick, aggressive mat that chokes out diversity and leaves little room for native flora to gain a foothold.

Recently, we began work at the southern tip of the island with a specific goal in mind: creating roosting and nesting habitat for endangered shorebirds. To do this, we sprayed back the Kikuyu grass, the first attempt with brush cutters was not successful.

As the grass died back, weeds quickly sprung up in the newly cleared earth. But while I was out there clearing these weeds, I looked closer at the ground and found something surprising.

Hidden gems in the weeds

Among the weeds were the unmistakable seedlings of native trees. I found two different types of Coprosma and a few young Karo plants. This sparked a bit of an ecological mystery. Where did they come from?

Aerial image of Motukorea in 1940. Source Geomaps / Auckland Council.

“There is no evidence of the island ever being forest-clad. It was cultivated for kumara and taro in the 1820s when visited by Samuel Marsden and RA.” – Esler, A. E. (1993). Plant Life of some Inner Hauraki Gulf Islands. Horticulture in New Zealand (Journal of The Royal New Zealand Institute of Horticulture), 4(2).

It is highly unlikely that these seeds survived more than 200 years in the soil bank. The most logical transport method is avian delivery—birds flying in and dropping seeds.

The unusual suspects

Usually, when we talk about forest regeneration in New Zealand, we look to our native pollinators and seed dispersers, like the Kererū or the Tūī.

However, on Motukorea, native fruit-eating birds are scarce. It is rare to spot a Tūī on the island and I can’t recall ever seeing a Kererū. So, who is doing the reseeding?

The island is, however, home to large populations of non-native birds like Feral Rock Pigeon, Starling and House Sparrows.

Feral rock pigeon on Motukorea

A novel restoration method

The theory is simple but fascinating. The clearing of the Kikuyu created a roosting and feeding area. As weeds fruited on the flats, the Pigeons and Starlings flocked in to feed. While they were there, they deposited seeds they had consumed elsewhere—perhaps from the few stands of mature native trees remaining on the island’s cliffs or even from the mainland.

It is a strange irony of conservation. We generally view feral pigeons and starlings as pests, yet in this highly modified landscape, they appear to be acting as the primary ecological engineers, bridging the gap that our absent native birds usually fill.

Thanks to our unexpected volunteers helping us replant the forest—one dropping at a time.

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Submissions on kelp forest restoration

Kina barren at Sail Rock. Photo by Shaun Lee.

Fisheries New Zealand are still stuck in a single-species mindset, managing kōura / spiny lobster as if they exist in isolation. The real measure of success should be the recovery of kelp forest coverage – the foundation of our shallow reef ecosystems. To their credit, FNZ are finally discussing area closures, but the framing remains too narrow.

My estimates (based on the best available information) show that restored kelp forests in CRA 2 (Hauraki Gulf Marine Park) could be worth 12–29 times more than the entire fishery. In CRA 1 (Northland), the foregone ecosystem services from lost kelp forests are even starker – between 100 and 228 times greater than the value of the fishery itself.

The packhorse lobster fishery in northeastern New Zealand should be closed immediately to allow predator populations to recover, avoiding millions of dollars in ongoing costs for culling long-spined sea urchins.

Submission on CRA 1 Closure

Submission on Draft CRA 2 Management Target Fisheries Plan

Submission on PHC1 Closure

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Assessment of the proposed Bream Bay sand mine’s impact on scallops

Tipa / Scallop in the proposed Bream Bay sand mine

The New Zealand government has just introduced ‘fast track’ legislation to bypass the usual checks and balances for environmental protection. This means less voice for nature in the application and approval process. To help address that gap, I’ve been looking into the impact a proposed sand mine might have on the tipa / scallop population in Bream Bay. I shared the report with quota owners who have been fishing the area, they agreed with my findings and have sent the report to Ministers.

Update: May 2025. I also found this document: Boyd 2017 Commercial-fishing Whangarei.pdf Which shows the location of commercial fishing in Bream Bay.

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A tī kōuka reef

This is an experimental idea for restoring severely degraded seafloor ecosystems in the Hauraki Gulf Marine Park. It was inspired by reforestation efforts in China, where desertification is being tackled using tools like sandbag tubes  and straw fences.

The idea I tested was based on the concept of straw fences and how they stabilise loose substrates. Underwater, a similar structure might:

  • Stabilise the seafloor by reducing sediment movement
  • Improve water clarity by slowing currents and allowing sediment to settle
  • Provide structure for marine organisms to attach to or shelter in

To test this, I needed to see whether natural fibres could be planted in the seafloor and remain in place. I chose tī kōuka (cabbage tree) leaves because they are tough, fibrous, and slow to decompose on land.

tī kōuka (cabbage tree) leaves
20 tī kōuka (cabbage tree) leaves
The triangle marker on the Ōkahu Breakwater

I collected ten live leaves and ten dead ones, plus two extras to bind them into bundles. The leaves were 67–80 cm long. I kayaked to the triangle marker on the Ōkahu Breakwater (-36.84498185012416, 174.8125985293282) and selected a site 10 metres north of this point, where the substrate shifts from broken shell (common around the piles) to soft mud.

On a calm, high-tide day 25 March 2025, I dived to 5-6 metres and planted the leaves vertically into the mud using a 2 × 2 cm, 40 cm wooden stake, driving each leaf 15–20 cm into the sediment.

The live leaves were planted in a cluster with 5–10 cm spacing. The dead leaves were placed in a similar cluster 1 metre east of the live group.

10 live leaves, Note the substrate was a little firmer here than were I planted the dead leaves.
10 dead leaves, 1 meter east of the live leaves.

Now I wait for nature…

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Close CRA 2

Close CRA 2

I am publishing my draft submission on CRA 2 early. Key points below:

  • The ecological imbalance caused by overfishing kōura (spiny rock lobster) in CRA 2 has led to the proliferation of kina barrens, devastating kelp forests along Northland’s east coast.
  • Kelp forests in the Hauraki Gulf could be worth up to USD 147,100 per hectare annually, far exceeding the $10.17 million export value of CRA 2. Kina barrens, by contrast, provide no ecological or economic value.
  • Fisheries New Zealand’s reliance on biased data, such as Catch Per Unit Effort (CPUE), underestimates kōura depletion. Independent research shows kōura populations, even in marine reserves, are well below natural levels.
  • The proposal to close commercial and recreational kōura fishing in the inner Gulf for 10 years is the largest fisheries closure ever suggested for the Hauraki Gulf Marine Park. However, fisheries independent data shows it’s not enough.
  • A new biomass target is precedent-setting and a significant step for Ecosystem-Based Management initiated by Sea Change – Tai Timu Tai Pari. A 3x BR target is essential to control kina populations, halt the spread of kina barrens, and restore productive kelp forests.
  • Independent data must be prioritised, and a precautionary approach adopted, including a full closure of the CRA 2 fishery. Further delays will only worsen environmental and economic losses.

Make your submission here.

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Brief for restoring extremely degraded seafloor ecosystems

Degraded seafloor - sediment - mudification

I don’t know how to solve this problem, so I am writing it up as a public brief for people smarter than me.

Brief for restoring extremely degraded seafloor ecosystems

Soft sediment marine ecosystems support diverse and productive biogenic habitats like shellfish beds, sponge gardens, tubeworm fields, and bryozoan mounds. Direct impacts such as mobile bottom contact fishing, and indirect impacts such as sediment pollution, reduce the function of these habitats. Stopping or reducing the impacting activities can help the habitats recover naturally over many decades. Active restoration (like mussel and oyster seeding) can be done in areas where the habitat is not recovering naturally; however, some environments can be too degraded for these methods.

Problem

In my opinion, at least tens of square kilometres of the Hauraki Gulf Marine Park are too degraded to restore with known techniques. In these extremely degraded areas, the seafloor is very soft, deep mud. It’s not lifeless; there are burrows and infauna present. But the areas would be more diverse and productive if the seafloor was less soft with less sediment in suspension. Even when pollution input has been reduced in these extremely degraded areas, legacy sediment is constantly resuspended – choking filter-feeding animals and smothering photosynthesising plants. It is difficult to visually convey the condition of these ecosystems, as visibility is usually less than 30 cm on a good day.

Solutions

To increase biodiversity in these areas, the benthic enhancement method must be low-cost at scale. This means traditional erect concrete and steel structures are not likely to be the solution. In my opinion, resurfacing the seafloor with demolition rubble or quarried aggregate is too extreme because it kills all the infauna. Anything heavy deployed will immediately sink into the mud, anything lighter than the mud will quickly be covered by sediment. A smarter solution might contain one of these elements:

  • Local pits or trenches to collect the most mobile sediment.
  • Dispersed erect artificial shellfish (think horse mussels) to slow benthic currents and allow sediment to fall out of the water column in fields or fences.
  • Regular deployments of waterlogged woody debris.
  • Biological concrete structures that grow using elements from the local environment.
  • Hardened local seafloor sediments (think mudbrick or mudcrete).
  • Growing dense algae at the surface which will 1) slow currents and surge to reduce resuspension 2) drop fragments for sequestration, feeding invertebrates, collecting sediment and seafloor hardening.

Caution

While these solutions will restore some ecosystem function they will not restore the original ecosystems. Hard surfaces will likely be first colonised by invasive species and the new habitat will offer more ecosystem services but be novel / new. We must first halt the destructive activities that degraded the seafloor ecosystems.