For years, the scallop shell has been a symbol of Kiwi summers – its meat golden-seared on a barbecue, skewered at a bach, or piled high at Whitianga’s famous Scallop Festival. But beneath the nostalgia lies something far less celebratory: New Zealand’s wild scallop populations have collapsed, their once-abundant beds dredged, degraded and, in many cases, destroyed.
Much of what we believed about scallops, from spawning behaviour to habitat preferences, is incomplete, borrowed from work overseas, or only partially tested in New Zealand conditions.
“We’ve taken a species we barely understood,” says Dr Jenny Hillman – a marine scientist at University of Auckland, “dredged it intensively for decades, and now we’re trying to work backwards and figure out how to restore it. It’s like cutting down a forest in a day and then realising it will take a century to grow back.”
Jen has spent her career studying bivalve restoration and says there are virtually no known untouched scallop populations left anywhere in the world. “We don’t even know what a healthy scallop ecosystem looks like anymore.”
It is the reason a small team of researchers are being funded by EnviroStrat’s Save Our Scallops venture, to piece together the science needed to rebuild what was lost.
EnviroStrat is an Auckland-based environmental consultancy, and evolved beyond advising local and global clients to originate, fund and execute its own impact ventures.
Save Our Scallops funds PhD students at the University of Auckland with philanthropic donations, while simultaneously doing the early work devising alternatives to dredging – exploring using nets and other methods used overseas in scallop aquaculture.
Recreational divers who once gathered a feed according to allowable catch now describe wastelands with grooves in the seafloor, and know to surface as they will not find anything.
Unlike logging, dredging removes not just the “trees” (scallops), but the topsoil of the seafloor itself.
To restore wild populations, researchers need hatcheries to reliably produce juveniles. Then they need to understand where and when to out-plant them to confirm those scallops can survive long enough to reproduce.
Three problems, none small.
Coda Canepa is a PhD student seeking to answer the questions about what scallops need to survive: “Things like: What size scallops survive best? What habitats matter most? What predators take them out? It’s all relevant and often unknown.”
He is working with a team at UoA that includes Siddharth Ravishankar, Tara Lepine, Brad Skelton and Jenny Hillman and the EnviroStrat team, testing scallops in muddy bays, sandy shallows, and high-energy exposed coastlines. They’re studying predation in the wild and analysing the difference between juveniles grown in hatcheries and those found in the wild, with every answer revealing another layer of complexity.
Apart from human predators, scallops are a tasty meal for starfish, octopus, snapper and other fish, and possibly rays too.
“If a starfish gets one scallop, that’s the scallop gone,” says Coda. “But these events are almost impossible to witness, so we need to infer from smashed shells, stomach contents and tiny pieces of evidence.”
Scallops are hermaphrodites – half male, half female – with bright orange roe inside. They release eggs and sperm into the water column, but temperature can alter the timing and behaviour.
Tara Lepine of UoA is leading hatchery culture experiments. Her video of a scallop spawning?- barely visible through release of sperm into hatchery water – shows just how fragile the process is.
This week was a breakthrough week in the hatchery as Tara unlocks the reproductive cues of New Zealand scallops. After trialling new spawning methods on broodstock, there were encouraging results across several treatments.
Using a shaker table – a lab device that gently agitates containers in a rhythmic motion to mimic environmental cues –Tara was able to stimulate 60% of the tested scallops to release eggs. A brief period of air exposure prompted additional individuals to spawn, resulting in a haul of more than four million eggs in a single day.
While the team is still assessing viability, with suspicions that the scallops may not have been fully conditioned, the volume collected was significant enough to establish an embryo rearing experiment, now underway.
Shortly they’ll know whether development has begun.
Regardless of the outcome, the day marked meaningful progress – each trial sharpening understanding of how to reliably induce spawning, a crucial step toward restoring Aotearoa’s depleted scallop populations.
Out on the water off Coromandel’s coastline, EnviroStrat’s Liam Hansard hauls up a lantern net to check the size of the scallops growing on farm.
As project manager for Save Our Scallops for almost two years, he’s hopeful about the future for the species and the commercial opportunity to sustainably farm scallops for those who love consuming them.
“Restorative aquaculture is farming supporting restoration and it’s exciting, because when you grow animals on the farm, you can supply a market…so you are taking pressure off the wild fishery. At the same time, you are growing these animals that can rewild into the natural population.
“Traditionally, there’s been a lot of efforts to try and reseed with just spat,” says Liam. “But really, you have a much better chance of your wild populations re-establishing if you put them in at a better size, so doing aquaculture of scallops is going to contribute to better restoration of scallops.”
The commercial initiative that led to Save Our Scallops began with a partnership with Lucas Evans – an Australian seaweed farmer now on the Coromandel Peninsula – and EnviroStrat CEO Dr Nigel Bradly.
“I was aware of a narrative in the background about declining scallop populations, challenges around recreational fishers dredging for scallops and I understood that we imported scallops as well,” says Lucas. “I could see there was not only a commercial opportunity but also an environmental opportunity as well.
“It’s exciting because the next stage beyond that is putting scallops that are grown here on the Coromandel on dining plates hopefully around the world. And it creates jobs – the farming and that support work through technology development, processing, marketing, the list goes on.”
EnviroStrat is testing three different nets including lantern nets, pearl and pocket nets. The team will shortly try an out-of-the-box concept using illuminated pots in the water to draw the scallops – ‘scallop discos’ – another reason to be endeared by this unique species.
Meanwhile, New Zealand’s top chefs need no convincing of the value of New Zealand scallops, or the nonsensical way that we’ve harvested them to near commercial extinction.
“It’s just a little treasure from the sea,” shares Ben Bayly, founder of Ahi Restaurant in Auckland, and presenter of A New Zealand Food Story on TVNZ. “They’re just so sweet, so delicious. [With aquaculture], I can see this making commercial sense. I think the scallop dredging wasn’t sustainable and just wasn’t giving us a fresh, live product.
“If you can sell the scallop live, you’re going to add a lot of value to it. If you can harvest and send to the restaurant – news flash, that’s how the rest of the world does it. But in New Zealand we have a culture of dredging scallops, opening them, putting them into a vac-packed bag and they sit around in a fridge, and we get these opened scallops.
“What you’re doing is devaluing the product.”
Jenny Hillman doesn’t eat shellfish. She grew up in Africa and says it was never in her thinking. Neither does she define the project as scallop restoration. “I call it sea-floor restoration. Scallops are the tool. The goal is to bring back a functioning ecosystem.”
Like the mussel reef restoration work being done elsewhere with groups such as Revive Our Gulf, scallops are seen as having the potential to stabilise sediments, create structure, cycle nutrients, and support a wide range of marine life.
“We still don’t understand how all these pieces fit together. But we know that when scallops were abundant, the system functioned differently. Better.”
Working so closely with a species must surely bring a connection. For all the cold logic of experimental design, restoration science is also unexpectedly emotional. PhD student Coda says while he keeps a firm focus on logic and science, his creative side can appreciate the beauty and relative sentience of the species.
“I separate the scientific mind from the emotional one,” he says. “But they do feel alive in a way mussels don’t. I had to keep a batch of scallops in a tank for a few days before putting them out and I really enjoyed hanging out with them. They have all these tiny eyes. They’re very…endearing.”
Coda’s creative side helps him stay buoyant through the tribulations and complexity of complex environmental problems. He has an MFA in creative writing and has published short stories — one exploring dam removal and river restoration in the US.
“Science is slow, and you don’t know if your work will ever matter,” he says. “Creative work lets me make meaning from what I see.”
The scallop story has also united people in coastal communities. If scallops return to the Coromandel, it will be because communities demanded it.
Local groups like the Opito Bay Ratepayers Association working with Ngāti Hei have fought to have fisheries closed, placed rāhui over entire bays, and guarded restoration sites with a level of care Jen says is unique to Aotearoa.
“I don’t publicise the exact locations of our experiments,” she says, “but honestly, we’ve never had an issue. Communities protect them. They understand what’s at stake.”
Volunteers can’t necessarily do the underwater work — diving regulations are strict — but they can monitor beaches, assist with intertidal work, collect historic knowledge, and advocate fiercely.
“Every bit of local knowledge helps,” says Jen. “Newspaper articles, old stories, photos. The past is a puzzle, and we’re rebuilding it.”
Coda is now five months into his PhD that will take three to four years. His research will inform guidelines for councils and communities – something that doesn’t yet exist for scallops.
Even with perfect restoration science, Jen says, the ocean needs time, and scallops themselves are slow
A legal-sized scallop (100mm) can take 2–3 years to grow. Larger scallops produce millions more larvae, so harvesting young is counterproductive.
“The ocean is so impacted that it will take multiple generations. But every step is progress. Progress is success.”
Save Our Scallops is a venture of and EnviroStrat’s charitable trust Ocean Regeneration Aotearoa. Alongside its scallop work, ORA has another project to restore reef ecosystems – the ecosystem approach that’s needed to truly bring back a species.
EnviroStrat is exploring a community event next year – a dinner with no scallops served – to raise awareness and funding for this work, which currently receives no Government funding.
Imagine celebrating scallops by not eating them and raising money so one day, we can eat scallops that have restored wild beds and been harvested sustainably in a whole new method for New Zealand.
A ‘scallop futures’ is the marketing concept – where those that get to consume the delicacy can learn about what’s involved at every step of the way in restoring healthy ocean conditions for them to grow.
Restoring this species requires unusual thinking. It’s hoped that the work happening right now in the Hauraki Gulf is the beginning of a generational shift from extraction to regeneration.
While we don’t know yet how to recreate a healthy scallop ecosystem, for the first time in decades, we have a more co-ordinated plan to find out.
- This article appeared in The Post newspaper. Its author Alison Smith is Communications and Marketing Lead for EnviroStrat.