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The days of recreationally diving for a scallop feast have all but vanished. (Photo: Getty; image design: Alessandra Banal)
The days of recreationally diving for a scallop feast have all but vanished. (Photo: Getty; image design: Alessandra Banal)

ScienceSeptember 1, 2022

Scallop season starts today – too bad we’ve almost wiped out the species

Guest writer
Guest writer
The days of recreationally diving for a scallop feast have all but vanished. (Photo: Getty; image design: Alessandra Banal)
The days of recreationally diving for a scallop feast have all but vanished. (Photo: Getty; image design: Alessandra Banal)

The rapid and distressing disappearance of our once abundant scallop beds has been blamed on a few environmental factors. But increasingly, experts point the finger at one clear cause of the decline: dredging.

Today, September 1, is the first day of scallop harvesting season. But New Zealanders feasting on fresh scallops this season will probably be eating them from one of only two main beds left open on mainland New Zealand, in Auckland’s Hauraki Gulf.

Forty years ago it was different. My family would go scalloping with our cousins in our favourite spots around the Kaipara Harbour in Northland. Dad and his brothers would dive for abundant scallops while we kids played in the pōhutukawa and chased crabs. Afterwards we’d sit on the beach in our 70s towelling shorts, next to a driftwood fire with a battered frying pan sizzling, and we’d eat fried fresh scallops with white bread and sand.

In 2018, the entire Kaipara Harbour finally closed for the taking of scallops after researchers found just one healthy bed left, following dredge harvesting used in the area since about 1960.

For decades now, New Zealand’s scallop beds have been closing due to depleted stocks, two more in March this year, leaving just those two critical beds in the Hauraki Gulf. This is the first commercial quota species to be so comprehensively brought to the edge of being wiped out.

As the philosopher Milton Friedman said: Only a crisis – actual or perceived– produces real change. It is hard to argue that this taonga, our scallop species, is not in crisis. It’s time to change the way we safeguard them.

Primarily, we need to ask questions about the role of dredging in the species’ decline.

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Dredging is a harvesting method that started commercially in most areas of New Zealand in the middle of last century, with the use of a bottom contact device called a Victorian box dredge. There are a variety of scallop dredges, and in different areas of New Zealand different kinds are used based on the type of seafloor. A dredge can weigh up to 200kg, with a toothed bar attached to the bottom so it can scrape 5cm deep into the seafloor.

Internationally, it is estimated one in five scallops die during the dredging and harvesting process. It has been banned in parts of Wales and Scotland. But in New Zealand dredging for scallops is still legal. 

There is more than one species of scallop in New Zealand waters, but the one we all know and love to eat is called the New Zealand scallop, or Pecten novaezelandiae. They are fast-growing, with high mortality rates related to the amount of stress they’re subjected to – whether that be environmental stressors such as temperature or water flow, resource availability, predation, or human-induced stressors such as dredging.

The end of a traditional summer delicacy

The beginning of the end arrived long before March this year when the last remaining mainland beds were closed. Major problems were surfacing as far back as 1980 off the Marlborough region’s coasts. 

A report on fishing and aquaculture, produced for the Ministry of Primary Industries, outlines how that year for the first time in New Zealand, a scallop population in the Marlborough region totally collapsed and had to be closed. 

Not long before that year, scallops had been plentiful, with a fleet of 216 licensed boats dredging up 1,244 tonnes in 1976. 

Fishers were cautious when the region reopened in 1982 and, this time, only 48 licences were issued. The region’s Challenger Scallop Enhancement Company also put in place a programme to reseed beds in Tasman and Golden Bay and a rotational harvesting approach was introduced with each bed only harvested once in three years.

This approach seemed to offset the species decline initially. Millions of dollars were poured into the scheme, dredging continued and a decade later the fishery seemed to be booming. Harvests bounced back as high as 800 tonnes in 1995. However, after that, annual catches dropped away. The last good year was 2002, when 700 tonnes were harvested.

By then, commercial fishers were no longer keeping to their rotational harvesting agreement, and the seeding programme had essentially failed. The fishery finally shut in 2016, with only about 20 tonnes able to be harvested. It has never reopened.

It would appear a tipping point was reached but, despite scientific reports blaming dredging, other potential causes of the decline were highlighted.

In 2009, Challenger operations manager Mitch Campbell told the Nelson Mail that the company had extensively researched the cause of the decline, to no avail. That same year former Challenger Scallop Enhancement Company chairman Buzz Falconer blamed the toxic residues from a former fruit-growing chemical factory by the shores of Tasman Bay for the scallop decline. In another interview, he suggested a massive flood in 2011, which pumped a great deal of sediment into the sea, had caused the loss of Golden Bay’s scallop harvest.

In 2016 Cawthron Institute marine scientist Paul Gillespie also blamed sedimentation for the closure, saying a slow build up over hundreds of years had finally hit home. 

In contrast, scientist Chris Cornelison, also of the Cawthron Institute, raised concerns last year about dredging, the only way scallops are commercially harvested in NZ.

Cornelison told Stuff the sea bottom was so degraded in parts of the Tasman Bay that it was impossible for sediment to settle in rough weather. The bottom, he said, had been dredged to uniformity, ironing out natural roughness and making sediment resuspend in waves above one metre. Scallops could not survive in this environment. 

A Fisheries Department study also pointed the finger at fish trawling for the failure of the reseeding program. Trawling uses a net with heavy weights which is towed across the sea floor. The study suggested scallop spat survival (spat are very young scallops which float in the water) was higher in areas that had not been trawled. This study also noted scallops survived underneath mussel farms, where there was no trawling.

In retrospect, the region was the canary in the coal mine, heralding what was to come for other areas. The same fate has befallen almost every scallop bed in New Zealand, including both locations where sedimentation is a problem and locations such as off shore islands where it’s not.

From Marlborough to the Kaipara Harbour, the Coromandel and the Far North, there’s a common theme: overharvesting and destructive harvesting methods that make it impossible for scallop spat to survive.

Activists monitor a fishing trawler in the Tasman Sea (Photo: Malcolm Pullman)

Communities fight back

For locals of Whitianga and the upper eastern coast, scallops are not only a delicacy, they’re the source of much tourist activity and income. Scallop beds were once so abundant that tourists would come from all over to harvest during the open season, an annual scallop festival was held, and the scallop shell stands proud on many a logo. The commercial industry was thriving, and some seafood shops exclusively sold scallops.

Ngāti Hei kaumātua Joe Davis says Ngāti Hei has relied on shellfish species as a core part of their diet and trade for generations. Their rohe was abundant with shellfish, so much so that their main method of gathering scallops was to await a wash-up on the beach, regarded as a gift from Māori god of the sea Tangaroa.

When Davis was a boy he saw thousands of scallops wash up along the shores after big storms. “This gift allowed us to hand gather scallops off beaches, as well as providing food for seabirds.” 

Will summertime scallops become a distant memory? (Photo: Getty)

Such bounty was once a common sight around the eastern Coromandel coast. But Davis’s local Kūaotunu beach has not experienced a wash-up for at least 10 years. He says that for years, until 2021, Fisheries New Zealand, the government department that has responsibility for New Zealand’s commercial fisheries, ignored Coromandel communities who pleaded with politicians and officials to take action and protect their local scallop beds. 

By then, the east Coromandel scallop fishery’s once-thriving commercial fleet had decreased from a peak of 23 boats, down to only four. “The government was doing nothing. So we took it into our own hands,” says Davis.

Ngati Hei joined with LegaSea, a non-profit that works to restore New Zealand’s marine environments (and for which this writer works), to conduct a dive survey of scallops beds. In an area of 25 metres squared, they found only one legally-sized scallop.

Linda Bird, owner of Dive Zone Whitianga and organiser of the Whitianga Oceans Festival, also became involved. “Being owners of the local dive shop, our customers were reporting poor catch opportunities when trying to harvest at both Opito and Home Bay. At first there was the hope that the beds were just shifting. But gradually, we came to the realisation that some of the lesser known beds had disappeared altogether.  Gone were the days of in, under and back in 10 to 15 mins.”

The dive shop volunteered its boats and divers for the survey, and Bird remembers feeling relief when the group’s combined efforts with a community campaign resulted in a rāhui. In September 2021, after more than 2,000 submissions, the rāhui was finally officially ratified by the government and the area’s once-famous scallop beds finally lay at rest.

“It was evident that the beds wouldn’t have survived another season,” says Bird.

In response, the Whitianga Scallop Festival, a longstanding iconic occasion with economic benefit to the community of $3.5 million, pivoted to become the Whitianga Oceans Festival.

The new-look festival is one that promotes awareness of sustainability in the marine environment.

Hope for the future

Lucas Evans loves all things Coromandel, including scallops. As wild scallops have declined, his job has been to find alternative ways to grow them.

“We’ve been trialing the process of collecting spat and growing it up through the various nets that they traditionally use in Japan, to try and get them to a mature stage.”

Because New Zealand lacks an existing scallop infrastructure, scallops are being grown using net “lanterns” hanging off mussel farming lines hung between floats. “We generally go out once a once a month for rotating the scallops through the various nets, putting them into clean nets, and assessing their health, measuring and those sorts of things.”

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Evans sees the process as an essential alternative to what has gone before. “Dredging for scallops is just a blanket sort of way of collecting the scallops and involves the big solid metal dredge being dragged over the sea floor,” he says. “On top of being labour intensive, hit-and-miss, and unpredictable, it also disrupts the seabed and upsets substrates that are reef systems and seaweed beds. It’s indiscriminate. “

LegaSea fisheries management advocate Trish Rea, who’s been gathering scallops and witnessing their decline throughout her adult life, says one thing is clear. “We cannot go back to managing our scallops in the same way and expecting a different outcome.”

Dredging, as the common link between every region’s scallop decline, must be banned, she says. “When the scallop populations recover we endorse the use of low impact, innovative harvest techniques… Our focus should be on not just rebuilding scallop populations, but a new approach that will prevent this ever happening again.”

Keep going!
lit up city with illustrations of trees and stars and snails
Turning on the lights impacts plants and animals (Image: Archi Banal/Getty Images)

ScienceAugust 31, 2022

Bring back the night: Why we need to preserve darkness

Contributing writer
lit up city with illustrations of trees and stars and snails
Turning on the lights impacts plants and animals (Image: Archi Banal/Getty Images)

Humans, and all the species we share a planet with, evolved for total darkness at night. With our urban areas increasingly flooded with artificial light, scientists, doctors and stargazers are making a case to preserve darkness.

The best thing about darkness is also the most frightening thing about it, the reason that makes it so easy to stay inside with the light switched on, and it is this: in the darkness you are small, and the universe is big. Ngā whetū gleam and sparkle. Te marama hovers, luminous, radiating the light of the sun you cannot see. In the darkness, the noises seem bigger, the rustle and chirp of other living things existing, not attending to you. There’s a gift in the darkness, when you wait for it: it’s the gift of noticing that the world sings songs you’re not part of, that a vast universe stretches beyond your skin. It’s as beautiful as it is terrifying. 

In urban Aotearoa – and increasingly in rural areas, too – these gifts of darkness are ignored. It’s the end of winter, and the earth is tilting back towards the sun. Still, twilights are early, and each evening hundreds of thousands of fingers around the country reach for light switches to illuminate kitchen benches and restaurant entrances and hospital corridors, truck stops and car parks and lumber mills. We let the light in. We keep the dark out.

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And all that light spills and refracts, tumbles upwards into the sky. The dark is less dark. Only the brightest stars gleam through the haze. Moths, on their way to pollinate flowers, cross the path of a streetlight they mistake for the moon. Confused, they hover, caught. 

For thousands of years, the tilt of the earth covered these islands in a cloak of darkness at the end of each day. The advent of electric light created a way to resist the inevitable darkness, more light for human wakefulness and work. But as normal – and as useful – as electric lighting is, the phenomenon is only a century old, and most of the world’s population didn’t get electricity until much later than that. In Aotearoa, Māori across the country observed the stars in a dark sky, the light of a fire or torch not travelling far. The light of the stars in darkness led people to these islands, and – as the celebration of Matariki reminds us – stars and darkness remain important to Māori today. 

hazy yellow light pollution rises from a city obscuring the sky
Light pollution creates hazy skies, concealing the stars. (Photo: Christophe Lehenaff/Getty Images)

This legacy of darkness can be read in biology, says Margaret Stanley. The associate professor of biology at the University of Auckland studies urban ecology, the way that living things are shaped by city environments. The species that humans share cities with have adapted to natural rhythms of light and darkness; human-created light can disrupt this, creating massive flow-on effects through the ecosystem.

Stanley gives the example of birds. “For birds, singing is absolutely critical to communicating – attracting a mate and holding a territory,” she says. One of the signals for birds to sing is the amount of light: like humans, they have circadian rhythms which are disrupted by light at night. “People complain about lights coming into their bedroom so they can’t sleep – outside in the tree, there might be a bird that can’t sleep for the same reason,” she says. 

But, in urban areas, humans have the power to alter the environment, often disregarding the needs of other species. The Auckland Transport lighting page, for instance, states that the council’s policy is to “alleviate the adverse effects of trees on lighting,” not considering the adverse effect of lighting on trees. Stanley says light can alter or damage how plants grow, form interrelated communities, and get pollinated.

lamp casts light on tree at night
Only thinking about how trees block lighting is an example of being human centred rather than thinking about the needs of other species (Photo: Chai Wai Chevy Wan/Getty Images)

It’s not just plants and animals that need darkness: it’s us. Guy Warman is an associate professor of anesthesiology at the University of Auckland, and studies chronobiology – the technical term for the biological clock. Traditionally, biology students are taught the principle of homeostasis, the assumption that inside an organism, everything is the same all the time. But more recent research shows this is not the case. Warman says our bodies are “rhythmic, strongly rhythmic, and that has an effect on our behaviour and physiology.” 

The biological rhythm is conducted, largely, by exposure to light and dark. “Our body [clocks] have an inaccurate period, and they’re regulated by light and dark,” Warman says. This inaccuracy allows patterns of sleep to adjust for the change in day length throughout the year. The biological clock is embedded in the other systems of the body, like hormones and digestion, and light and dark help these systems to synchronise and communicate. While daylight tends to be stronger than artificial light, it can still impact circadian rhythms. You’re not imagining it: getting out of bed at 7am in the winter dark is much harder than in summer – without morning light, you’re quite literally less awake. 

“Sleep is really undervalued,” Warman says. “It’s seen as a waste of time, but it’s essential for immune function, memory consolidation, wound healing, clearing byproducts from our body and brain.” The widespread availability of electric light, as well as work cultures that create an environment for revenge procrastination, do not encourage people to pay attention to their need for rest, and – closely connected – their need for darkness. 

The Milky Way, shot from Wānaka. Dark skies are important for regulating our circadian rhythms of sleep and wakefulness. (Photo: Sellwell, via Getty)

It’s understanding the cultural, social, spiritual, and biological value of night that inspires the work of people across the country who advocate for protection of the darkness. 

One way this is being done is through dark-sky places. The International Dark-Sky Association, or IDA, is a global organisation that can accredit locations that protect darkness. In Aotearoa, there are four such places: Rakiura and Aotea, which are dark-sky sanctuaries; Aoraki-McKenzie Basin, which is a dark-sky reserve; and the smaller Wai-Iti dark-sky park near Nelson. 

There are more than ten other communities around the country in the process of getting accredited. These projects are linked by Aotearoa’s Dark-Sky Network, an organisation aiming for New Zealand to eventually be the first accredited dark-sky nation. 

On a practical level, becoming a dark-sky place means meeting stringent requirements to shield and dim lights, making sure that all outdoor lighting only goes to where it is needed, rather than spraying uselessly into the sky. Managing a dark-sky place means taking regular readings of the darkness, ensuring it’s pristine, and holding public events to connect communities with each other and the glimmering blackness above. 

lines of light show the location of streets. hazy dark sky and light pollution
Light pollution in Christchurch shows how light directed into the sky wastes energy. (Photo: Sky Images/Getty)

“Our night sky is a taonga,” says Ralph Bradley, manager of the Wai-Iti reserve. A keen astronomer, Bradley started the six-year process to create the park after he couldn’t get planning permission for an observatory on his own property. While not everyone can get to dark-sky spaces, he says creating darkness can start in your own backyard, with shielding lights and using fewer of them, helping to make night safer for the creatures who depend on darkness.

It also makes a lot of economic sense to protect darkness, says Nicky McArthur, an ecologist who became involved with dark-sky protection due to her role protecting the Hutton Shearwater birds endemic to the Kaikōura region. Fledgling shearwaters, leaving the safety of their alpine nests for the first time, mistake a lit road for the shine of light on seawater and crash into solid ground. Working with the council to dim streetlights to prevent this tragedy, McArthur realised that preserving the darkness of Kaikōura could create tourism opportunities for the South Island seaside town in wintertime. But getting local businesses and developers to understand has been a struggle. 

“I need people to know that we’re not going to be in the dark, we’re not going to switch the lights off,” she says. Shielding outdoor lights, directing the brightness downwards, doesn’t mean reverting to a pre-electricity age: instead, it helps humans and animals to have dark when they need it, and light when they need it too. 

Dark-sky certification is only one way to protect the darkness. City councils, in providing street lighting, are one of the main sources of light pollution (although commercial and industrial lighting is a concern too). The numbers are staggering: there are 124,000 streetlights in Auckland, 48,500 in Christchurch, and 13,000 in Dunedin. In recent years, many councils have been phasing out older, less efficient sodium lights, and replacing them with LEDs, controlled by a central management system that can manage the lights remotely. Running these lights costs millions of dollars each year, but installing shielding and dimming lights once traffic volumes are low – now standard practice – can reduce the expense as well as the amount of light spill. 

But while the practical changes brought in by dark-sky projects or LED lights matter, it’s also vital to change our cultural relationship to darkness. “We want light everywhere at night so we feel safe,” says Stanley. But while lighting may create a feeling of safety, there’s no strong evidence that it materially reduces crime. Instead, over-lit cities waste vast amounts of energy and prevent people from the biological, psychological and cultural benefits of darkness and stars.

“I think we’ve forgotten to look up,” says McArthur. “The night sky evokes awe and wonder – it has been so critical through the history of humanity, for explorers, for Polynesian navigators.” Keeping the sky dark ensures that that awe can be passed on to future generations, a reminder that our human bodies are subject to the same rhythms as those of  other animals and plants. After all, the brilliance of the stars isn’t going anywhere; making friends with the darkness lets more of their light filter in.

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