Toheroa: Rejuvenating a Delicacy

Dr Ocean Mercier

Māori have always been scientists, and we continue to be scientists. Our science has allowed us to live, work and thrive in the world for hundreds of years. My name is Dr Ocean Mercier, and I’m a lecturer in pūtaiao Māori at the Victoria University of Wellington. My job takes me all over the world to talk about Māori science and how traditional knowledge is being married with western science here in Aotearoa in order to find innovative solutions to universal global issues.

In this programme, we are going to show you how these worlds of science are intersecting and how the paths to our future are being formed.

Dr Ocean Mercier

I ngā wā o mua ko te toheroa te tino kai a te hapū kei te tai hau-a-uru o Te Ika-a-Māui e noho ana, ā, ka taonga ki a rātou. (The toheroa was once a staple in the diet of hapū on the west coast of Te Ika-a-Māui and considered a taonga

Shellfish numbers were plentiful for centuries, but the move towards industrial harvesting and canning would have a devastating effect on toheroa numbers. The toheroa population collapsed after years of overharvesting.

For several decades, a ban on harvesting has been in place, and the food that once nourished hapū all along the coast are no longer making it to the dinner table.

Dr Ocean Mercier

Kei a Jim Te Tuhi, kaitiaki toheroa, ngā kōrero tuku iho a tana kuia, e pā ana ki tēnei mātaitai rongonui o Aotearoa. (Toheroa kaitiaki Jim Te Tuhi still carries stories passed down to him from his grandmother about this delectable icon of Aotearoa.)

Jim Te Tuhi

Yeah, I remember these old people talking about toheroa and how the name toheroa came. And they were relating to these people that came from Kaitaia that were out pigeon hunting looking for these kūkupa. And they wandered out of their area and came towards the south, and they were chased by these people from Te Roroa I think it was. They kept chasing and chasing until they came to the beach here, on Ripiro Beach, up towards the bluff. They were getting hungry because they hadn’t had a feed all day, and they said, “Oh well, there must be some food here, maybe some mussels around.” But they had a look around. They couldn’t find any at this stage, but anyway, they were digging in the sand, and nothing there. So their chief decided to climb up onto the hill at the bluff there and pray to the gods for food to save his people, and then a big gust of wind came along and was blowing behind him and was saying, “Tohe-roa, Tohe-roa”, so they dug – and of course toheroa means ‘persist longer, persist longer’ – they said oh, must be digging. So they kept digging, digging again, and sure enough, they came across this shellfish, and they pulled it out, and here was this big shellfish, and then they ate it and they were nourished and were able to carry on. And on leaving that area, the chief says, “We will now call this shellfish toheroa.”

Shade Smith

My role in the Toheroa Abundance Project was to identify kaumātua who lived along the beach and had a long association with the beach to try and pick their brains as to what they felt was impacting toheroa populations. After we’d conducted the interviews, there was a population survey of the beach to give us a snapshot of the current status of the toheroa stocks where, because we had built up those relationships with those people, those kaitiaki, kuia, kaumātua on the beach, we went back to them and said, “Hey, would you like to come and learn about, you know, how the scientists conduct their surveys?”

So basically, we take a 0.25 metre square quadrat, dig it out, count all the toheroa and tuatua, record the measurements, the lengths and then we move on 10 metres down the shore.

And so it showed them what the survey involved, and on the day of the survey, over 30 individuals that came as iwi helpers and left as kaitiaki.

Dr Ocean Mercier

E tino tika ana hoki kia whai kaitiaki te toheroa. (And it’s kaitiaki that the toheroa are in desperate need of.)

I te haurua tuatahi o te rautau rua tekau, ka nui te hiakai o te Māori me te Pākehā ki tēnei mātaitai rangatira, ana, ka kūtere atu rātou ki ngā tahatai ki te kohi. (In the first half of the 20th century, the delicacy was popular with both Māori and Pākehā, who descended onto the beaches in swarms.)

Nā te tipu matomato mai, ka whakatūria he whare umanga ki te tapataphi me te rau atu ki rō ipu, ana, ko te toheroa tētahi o ngā mea tuatahi i hokona atu ki tarawāhi. (They were so plentiful that canning factories were set up to process them, and toheroa became one of our first manufactured exports.)

Engari, nā te kaha hiahia ki a ia, ka tata mate te toheroa, ā, ka whakaritea kia rua rā noa iho i te tau mō te hauhake toheroa . Nō te tau waru tekau mā tahi, ka horapa he rāhui. (But demand almost drove the toheroa to extinction, and harvesting was restricted to 2 days a year. In 1981, a full-scale ban was enforced.)

Dr James Williams

Past research work that’s been undertaken on toheroa has mainly focused on understanding how many toheroa are present at the key beaches in the country, and that’s related initially to the commercial harvesting of toheroa, which was quite intensive in the early part to the mid part of the 20th century.

Current research is focused on trying to understand the factors that are affecting toheroa, because they haven’t reached their formerly abundant levels at many of the beaches that they occur at, and people are asking why is that? What are the main factors that affect their abundance? Specifically, what affects their recruitment – that’s the addition of new individuals to the population – and what’s causing them to die off – their mortality? So the recent research was aimed at trying to understand what are the current levels in the Far North beaches, which historically, two of the main areas for toheroa in the country – that’s in the Far North at Ninety Mile Beach and at Ripiro Beach to the west of Dargaville. So how many toheroa are there, what are their size and what’s the distribution of toheroa beds along the beach? – and to compare that with historical levels.

Ocean Mercier

Kāore hoki te rāhui i tau ki runga i te hauhaketanga, i tino awhina i te oranga anō o tēnei mātaitai.(Even the ban on harvesting has had limited impact on the recovery of the shellfish.)

I kite-ā-kanohi a Jim rāua ko tōna hoa tiaki toheroa a Barry Searle i te tāmate haeretanga o te toheroa, ā, ināianei kei te whawhai rāua kia ora anō. (Jim and fellow toheroa conservationist Barry Searle have lived through the massive decline in toheroa and are fighting to save this iconic shellfish.)

Jim Te Tuhi

Well, first I met Barry in the army years back when it was in compulsory military training, and of course, he’d been on the beach, and his people live not very far from us. He was playing around with toheroa up the other end, and I was playing around with toheroa down at our end.

Barry Searle

The toheroa were virtually extinct on the beach at that stage, but out in the surf where we work in the high surf, we were finding the odd toheroa amongst out tuatuas. So knowing what had happened here, we started taking these – a dozen at a time or so – and starting beds on the beach. And this was successful, so we started one, and then two, and then three beds, and then from these beds, the toheroa themselves were able to establish and spat, and we gradually got the toheroa to come back – until today, where we’ve got a good level of toheroa on the beach, but it’s not expanding any more.

Dr Ocean Mercier

Kei te mahi tahi a James Williams ki a Shade, Barry me Jim. (James Williams has been working alongside Shade, Barry and Jim.)

Kua whakarewa tikanga aromatawai ia, hei taunaki i te mātauranga ki te mana o te pūtaiao. (He’s introduced survey methods that back up mātauranga with hard science.).

Dr James Williams

The aim of doing a survey is to try to understand what’s out there right now – how many toheroa are out there, what size are they and where are the toheroa beds distributed along the beach?

Now to do that, toheroa are naturally aggregated into dense beds for many reasons, including reproduction. So you can go kilometres along the beach and find no toheroa but then find a very dense bed where you get lots of individuals all crammed in together. So to survey it, we want to try and understand where those beds are likely to be and put most of our sampling effort into those beds. To do that, we need to do a stratification or a mapping exercise, and that’s really important work that Shade carried out with tangata whenua – driving along the beach and inspecting the beach every 2 kilometres down or if there were signs of toheroa from the surface of the sand and then taking a sample from inside the bed of toheroa or at every 2 kilometres and counting and measuring the shellfish inside that sample. And from those data, we can then allocate our survey effort to put more effort into sampling where we expect more of the toheroa to be.

Dr Ocean Mercier

By using scientific surveying methods and tapping into mātauranga Māori, the Ministry for Primary Industries had engaged NIWA, independent contractors like Shade and kaitiaki Barry and Jim to try and rebuild the toheroa population. The first step involved getting accurate data on the numbers.

Toheroa were once prolific on beaches of Northland, but mass harvesting had obliterated numbers. A 30-year ban on the harvesting of the taonga shellfish had not significantly improved the stock, and iwi and the Ministry for Primary Industries have been working to revive the species. It was important to ascertain what the numbers were and to tap into the knowledge of kaitiaki like Barry and Jim.

Kei te uru o Tākiwira te tātahi o Ripiroa. Koia te aronga nui o ngā rangahau pūtaiao me ngā rangahau taipito kōrero. (Ripiroa Beach west of Dargaville is the focus of much of the scientific and anecdotal investigations.)

I te rā nei, kei te toro Shade i a Barry rāua ko Jim, te hunga e tino mōhio ana ki ngā huringa o te takiwā i roto i ngā tau me te pānga o tērā ki te toheroa. (Today, Shade’s visiting Barry and Jim who are knowledgeable in this changing landscape and its effect on the toheroa population.)

Jim Te Tuhi

They say that, or grandmother says that the toheroa, when they spat out in the tide, after about 18 days, after rolling around those 18 days, so there’s two tides in that, that’s 36 [tides], then they come up when all the elements are correct, they came up, up onto the – into the huka, which is the foam on top of the water, OK, and Tāwhiri-mātea the elder brother blows it up on to Tāne where the pīngao, the pīngao is standing up there, and it catches, it catches the spat, which is a liquid, and it comes down the stem of the [plant] and then settles into the sand. And there, that’s the place where the shell takes place of forming, up in the sand dune – eventually comes back down into the sea and down into the beach.

Barry Searle

Dunes are made by the plants and the water sweeping up to the plants, and these are higher, drier and warmer, and that’s really gives a place where they hatch, and that was also sort of taught to us by the old people. And so the systems do work together, and without one – the plants play an important role in the whole catching system of the beach.

Shade Smith

It’s important to use mātauranga and the anecdotal information that we’ve collected from people like Jim and Barry. Their stories have come about over a long period of time.

Scientists really come in to use these sorts of stories as a bit of a roadmap for our investigations, and in this case – when we’re talking about toheroa breeding – the relationship between toheroa and the dune plants such as pīngao and spinifex. These dune plants play a big part in forming the dunes, and the dunes are an important part of the beach system in that they are the transition between the land and the sea. The topography of the beach changes according to where these dune systems are. Where you get dunes is quite often the beach slope is different. The topography of the beach is a very important component in influencing the swash climate for an animal like toheroa. The swash climate is critical to the way it moves up and down the beach. These animals surf, they pop up out of the sand, they use the swash to surf up and down the beach, and so when Tāwhiri-mātea blows the foam or the huka, what we believe is that the huka and the spat is being washed up the beach in the swash, and with an onshore wind and the right slope, formed by these dune systems and the plants, it finds its way into that top area of the beach.

Dr Ocean Mercier

The swash zone is the upper part of the beach between the backbeach and surf zone. The zone is alternately wet and dry and is home to the toheroa population. It is here between the high and low tide that population surveys are undertaken.

Shade Smith

Well, these juvenile toheroa, you can see that there’s a few different sizes, so they’ve all been spawned over the last few months. They’re found in this area of the beach, which is more towards the – to the shore compared to the ocean because the waves or the swash climate up in this area of the beach is not as great as further down. And so, because they don’t bury as deep, they’re not pulled out of the sand compared to down the shore. And so, over time, the swash kind of activates them into a band, and so the chances of an egg and a sperm coming together in the milieu of the surf is quite slim.

So by aggregating together into these beds, the adults, once they’ve spawned their egg or their sperm, the chances of them coming close together are much higher and so therefore increasing the success of reproduction, and so this area of the beach is where the juvenile settlement band occurs, which is separate to the main bed, which is just further down here. And over time, as they get bigger and more able to withstand those bigger waves or the higher sort of swash climate, then they’ll gradually move down the shore to join the main bed.

Dr Ocean Mercier

I te rā nei, kei te whakahaere rangahau-ā-ara kia mōhio ai e hia rawa ngā toheroa ki konei. (Today, the team are conducting a transect survey to estimate the current population density

Kei te whai ara pūmau ngā kairangahau, ā, ka tatauhia te maha me te rahi o ngā toheroa kei tēnei ara. (The survey follows a fixed path – the numbers and size of toheroa along this path are counted.)

Dr James Williams

Well, we’ve arrived at the transect position, which we’ve found with our GPS. We’ve had predetermined positions to find on the beach, and this is one of them. So here we are now, we’re just going to start doing a transect, and this is the gear that we use to do the transect. Sampling the transect involves running a line from high water mark down to the low water mark and digging holes at set intervals along that transect line. In this case, it’s over a toheroa bed, so we’re digging at 5-metre intervals. And the guys at each position along the transect, they place a square quadrat that’s half a metre by half a metre, so that we’re taking the same unit area of sand from each position along the transect.

Obviously in a high-density bed of toheroa, we don’t really want to be using spades to do the digging. We try and dig the holes by hand where possible to minimise damage to the toheroa. So they have to dig the sand out and put it into that trolley there that’s got a sieve in the bottom, and they dig down to a depth of 30 centimetres so that we’re taking a sample of the beach that contains the toheroa and perhaps tuatua as well. And then the trolley will be run down to the surf and rinsed out, leaving the shellfish behind on the sieve, that we can then count and measure how many of each species are in the sample.

Quite a good toheroa bed – this is just from a quarter metre squared area – and we’ve got quite a lot of large toheroa here, couple of tuatua as well and some smaller toheroa. So every quadrat that we take, we have to measure the shell length – that’s the longest axis of the shell of each individual, we’ll ID whether it’s a tuatua or a toheroa, and we can do that using our electronic callipers here, the digital callipers. The data’s entered straight into the computer there. So just looking through the sample, we’ll get lengths and counts of obviously all the shellfish in the sample, and from those data, we can then work out how many would have been in the whole length of the transect, and then we can scale that up to the whole length of the beach.

Dr Ocean Mercier

Using the raw count, you can arrive at an estimate of the actual density of shellfish for that beach and track the population by resurveying the same beach area through time.

NIWA’s review of published material, its population survey and anecdotal observations from kaumātua like Jim Te Tuhi were beginning to paint a picture of the factors affecting the toheroa population. The next step for scientists and kaitiaki was to find out how this information could be utilised to increase toheroa numbers.

The once healthy stocks of toheroa on Northland beaches was a distant memory to older locals, ā, ahakoa te rāhui toru tekau mā rua tau te pakeke, auare ake (and a 32-year ban had done little to increase the population). A nationwide survey to get a greater understanding of the toheroa population utilised western science, mātauranga Māori and local knowledge and has delivered some concrete ideas about why the ban on the toheroa still can’t be lifted.

Dr James Williams

The results of the transect survey we conducted in 2011 at Ripiro Beach were that we found over 40 beds of toheroa of varying density from very high density to low density. And they were interspersed along the beach, mainly in the central and northern parts of the beach, but interspersed between areas of the beach that contained very few or no toheroa. And that’s quite normal for this aggregative behaviour. Within those beds, on average, there were about 3,000 toheroa per strip of – half-metre strip of transect running from high to low water, and scaling all of the data up from the nearly 1,000 quadrats and 62 transects, we estimate there were about 13 million toheroa plus or minus about 15%, but only 1 million of those were of 75 millimetres or more in shell length, so that, there’s only, there’s very few large toheroa there, and that’s quite a concern.

Dr Ocean Mercier

Kua tohua ngā kaipatu toheroa, ā, kua aro nui te roopu ki te whakatau i ētahi take. (The primary threats to toheroa have been identified, and the team have focused on a number of issues.)

Jim Te Tuhi

When they had the open season, the minimum size was 3 inches, but it never had a maximum. You need a maximum if you got a minimum. And of course Barry and I have been through the sand dunes and through the middens, and we never found a toheroa over 4 inches, so you know, that must tell us something – that the Māori never ate that particular thing. But with the Pākehā thing saying 3 inches, it is illegal to be in possession of anything less than 3 inches. So what they’re saying, “Eat everything above 3 inches”, and that’s what they did, and now look at our resource, it’s gone.

Barry Searle

A black-backed gull can take 30 shellfish a day each, and these have exploded in numbers since the take of the eggs. In the old days, even when we were kids, we’d go and gather the eggs for food and making sponges, they make beautiful sponges. And this kept the gull population regulated, whereas now we’ve got none of that happening, and the gull numbers are just increasing, increasing, increasing. Subsequently, more and more toheroa are being taken off the beach by the birds.

Shade Smith

Every so often, you get a mass mortality event where a certain set of environmental conditions – nice calm seas, continual easterly winds – and it doesn’t allow the waves to swash up the beach and over the beds. A few days of that and, essentially, the toheroa cook in the sand. Now these are natural events, so there’s nothing much that we can do about them as individuals. However, all the other factors that are influencing the toheroa population – the human-induced impacts – blunt the toheroa population’s ability to rebound from those mass mortality events, and that’s really where we have to focus our efforts on.

Dr James Williams

Our review and the anecdotal information together with the results of the recent surveys – that information really needs to be communicated more widely to those in positions that could make important management decisions, but also to try and educate children in schools particularly coming through about the factors that affect toheroa and how our human behaviour can actually influence whether they’re successful or not.

Jim Te Tuhi

Well, the future for our vision for toheroa is that there’s to be more education, has to be put out of the resources. We’ve been doing schools all the way down from Muriwai right to Te Hapua, going right through the whole island there, and the primary, intermediate and some of the high schools and kōhanga reo. So if we can produce more books and more things about it and get the schools really interested, I think that’s what it’s all about. Because it’s for their futures, we’ve had ours. But I mean, I want to see my great-great-great-grandchildren have toheroa, enjoy what I had when I was growing up with my grandmother.

Dr Ocean Mercier

Kua hono te pūtaiao Pākehā me te mātauranga Māori kia rahi ake ai ngā mōhiotanga e pā ana ki te toheroa (Western science and mātauranga Māori have come together to further the knowledge about the toheroa) and to highlight some of the potential issues that are affecting its re-establishment as a sustainable resource.

While we are still some time away from being able to harvest toheroa again, it’s hoped that the population can be rebuilt, and toheroa will once again be a delicacy we can all enjoy.

Acknowledgements
Video courtesy of Scottie Productions.
© Scottie Productions2013.