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 Jen 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. It is the reason blue economy venture developer EnviroStrat formed Save Our Scallops, which brings together researchers, iwi, marine farmers and industry in a multi-year programme to restore abundant scallop populations whilst creating a viable scallop aquaculture industry.
Save Our Scallops partners with the University of Auckland, funding three PhD researchers to advance hatchery, farming techniques and restoration science. After years of over-fishing, high-impact dredging, land-based sedimentation smothering scallop beds and disease pressures, this coordinated approach is building the knowledge needed to create a restorative aquaculture model, growing scallops in suspended nets to support both market demand for NZ scallops and the recovery of wild beds.
To restore wild populations, researchers need a reliable source of scallops, which can be provided by donation a portion of farmed scallops. Then they need to understand where, how and when to out-plant them to confirm those scallops can survive long enough to reproduce.
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 habitat features are most important? What are their main predators? It’s all relevant and often unknown.”
He and the team at UoA have begun by testing scallops in a sandy shallow area, looking at habitat complexity. They’re studying farm-raised scallops only at this stage in the work, and with every answer, another layer of complexity is revealed.
Apart from human predators, scallops are a tasty meal for starfish, octopus, snapper and other fish, and possibly rays too.
“These events are rare to witness, so we need to infer from smashed shells, stomach contents and tiny pieces of evidence,” says Coda.
Scallops are hermaphrodites - half male, half female - with bright orange roe inside. They release eggs and sperm into the water column, but temperature, among other things, can alter the timing and behaviour.
Tara Lepine of University of Auckland is leading hatchery culture experiments. Watching scallop spawning - barely visible through release of sperm into seawater - shows just how fragile the process is.
This week was a breakthrough in the hatchery as Tara ‘unlocked’ the reproductive cues of New Zealand scallops. After trialling new spawning methods on broodstock, there were encouraging results across several treatments which could pave the way to future hatchery development to produce scallops at far great numbers.
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 growth is occurring.
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 and aquaculture PhD student Siddarth Ravishankar haul up some lantern and pocket nets to check the size and condition of the scallops growing on farm.
As project manager for Save Our Scallops, Liam is hopeful about the future for the species and the commercial opportunity to sustainably farm scallops for those who love consuming them.
“Achieving high survival and growth to market size in 12 months is a significant milestone” says Liam, “we’re confident in our ability to farm the scallop.”
He says the real bottleneck is accessing seed in meaningful quantities, which is the current priority to enable more farming and restoration.
“Restorative aquaculture is farming supporting restoration and it’s exciting, because when you grow animals on the farm, you can supply a market... taking pressure off the wild fishery. At the same time, you are growing these animals to restore the natural population.
“Traditionally, there’s been many efforts nationally reseeding scallop beds with just spat,” says Liam. “But, evidence suggests reseeding larger 3-5cm scallops really improves survival and chances of wild beds re-establishing, so doing aquaculture of scallops really benefits restoration.”
The commercial initiative that led to Save Our Scallops began with a partnership with Lucas Evans – founder of Premium Seas on the Coromandel Peninsula – and EnviroStrat CEO Dr Nigel Bradly.
Says Lucas: “I was aware of a narrative in the background about declining scallop populations, challenges around recreational and commercial fishers dredging for scallops and I understood that we imported scallops as well. 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 around the world. And it creates jobs – the farming and that support work through technology development, restoration, processing, marketing, the list goes on.”
EnviroStrat is testing different net types including lantern nets, and pocket nets to understand which are most effective. The team will also shortly trial an alternative fishing method using an out-of-the-box approach from overseas that involves illuminated pots in the water to draw the scallops – colloquially called ‘Disco Scallops’.
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 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.”
Jen 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 a 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 a Masters of Fine Arts 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 Hillman says is unique to Aotearoa.
“We 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 a 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 growing.
A legal-sized fished scallop (100 mm) can take two to four years to grow. Larger scallops produce millions more larvae, so harvesting them 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 funded through a charitable trust established by EnviroStrat, called Ocean Regeneration Aotearoa (ORA) www.oranz.org.nz.
Restoring this species requires innovation. 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 coordinated plan to find out.