They’re ancient, boneless, jawless creatures with round, gaping mouths filled with tiny nightmarish teeth – but these fascinating creatures are a taonga and a delicacy and they’re under threat.

“He manawa piharau” is a well known whakataukī in Taranaki. It refers to the determination and endurance of the piharau to swim upriver against great odds.

There are many lamprey species in the northern hemisphere, fewer in the southern hemisphere and here in Aotearoa we have just the one – piharau, also known as kanakana in the South Island, and pipiharau, pihapiharau, korokoro and nganangana besides. Its western names are Geotria Australis and the pouched lamprey – the latter a reference, says Dr Jane Kitson, to the “floppy sack” under the chin of the adult males. “They’re not very attractive at that stage,” she laughs.

Kitson (Ngāi Tahu, Ngāti Mamoe, Waitaha) is an ecologist and environmental scientist with a background in traditional ecological knowledge research. She works with whānau in Murihiku at the bottom of the South Island to help them better understand and protect the species. “I’ve predominantly worked with threatened species and connecting science with mātauranga. I’m a tītī harvester myself, so I understand that deep connection to them.”

Kanakana are “very special and very ancient” she says. “We have fossils dating back 360 million years that predate dinosaurs, tuatara. They’re from the time when all the continents were joined up.”

This is of course reflected in their unique physiology – they are one of the only living representatives of the most primitive vertebrates, the jawless fishes. “The kaitiaki I work with have done an amazing job at promoting them as a taonga rather than a ‘vampire of the sea’ which it often gets labelled as. It has had a very bad PR rep.”

A very secretive fish, there is a lot that still isn’t known about them, and this is hindering the ability of iwi and state agencies to protect dwindling numbers. Their life stages are so different from one another that scientists in the past have mistaken them for different species.

Piharau/kanakana can be found far and wide, although their abundance declines the further north you go, with the highest numbers centred around Te Pātaka o Rākaihautū, Otago and Murihiku. They do however behave the same way across the country. “The babies leave the spawning site and head downriver, hiding in the sediment for about four or five years. They’re just filter-feeders, filtering out the water and the bits and pieces in there,” says Kitson.

Once they have matured into “mini-adults” they make their way out to sea. There they start the parasitic stage of their life-cycle, where they attach to larger fish using their disc-shaped mouths, and drain fluids from their host. Inside their mouths is a tongue that’s stranger still – a raspy razor sharp blade that helps them scrape away tissue and scales. “They use their mouths for climbing too, rocks and waterfalls,” Kitson says. “They’re good at climbing, I know this from having them in my wash house where they climbed up the walls.”

While at sea they transform from a kind of muddy brown to a bright blue for better camouflage. “Five odd years out at sea, and then they come back.”

The period of migration back up the waterways during the cold winter months is when the adults are caught and eaten. For the river iwi who have eaten this delicacy for generations, its appeal hasn’t waned.

Sam Tamarapa (Ngāti Ruahine, Ngā Rauri, Te Āti Haunui a Pāpārangi) has been involved in efforts to manage and protect piharau in Taranaki for many years, but his interest in them started as a young boy tagging along with uncles in Whanganui.

“One day I went out to help my uncle and cousins reestablish what we call the pā piharau, the site where we catch them, and I became fascinated.”

He reconnected with the practice after moving home to Waitara in Taranaki, and meeting some piharau fishermen. Then one day, a man who he would often fish with told him he was moving away – but the spot where they fished together was designated for his whānau only. Tamarapa went to the man’s father and asked if he could continue fishing there. “He said: ‘Of course you can, as long as when you catch the fish, you share it out.’ So that started my journey in terms of my hands on involvement,” Tamarapa says.

He’s since become an expert in the ways of the piharau. “The species is quite shy. It travels at night; it travels when the rivers are in flood, and they seem to like the coldest, darkest, wettest nights. They shy away from the daylight. There’s probably a link with the moon as well because the tides can push them upriver.”

He too is aware of the gaps in knowledge held about piharau. “When they’re moving and migrating up the rivers, their sole purpose is to spawn. They’re like salmon, they’ll swim upstream, find a spot and spawn there.”

Although different iwi have their own methods for catching piharau and kanakana, one thing they share is that those catching them today are using essentially the same methods as their ancestors. On the Waitara river, Tamarapa says, the whakaparu is still a common trapping technique.

“The old people had it all worked out – they would go into the rivers, take out great big stones and place the mats there, made from woven ferns. Then they’d anchor one side with stones, so the front was left to rise up. When the piharau are coming back up and want to hide away and protect themselves, they’ll burrow under those mats.” After that, it’s a matter of pulling them out by hand, he says.

The lamprey is considered a delicacy all over the world – especially in South America, Japan, and among First Nations peoples in Canada. King Henry I of England was known for his love of them and is reported to have died from a “surfeit of lampreys”.

“It’s quite fatty, quite oily. The old people used to say if you can eat two or three of the things in one sitting you’re doing well,” Tamarapa says. “You eat the whole thing. They have no bones, just cartilage. In Taranaki here we grill them on a fire outside. Put some netting down on embers – we have different ways of tying them together – and we lay them down on the netting and grill them. I’m getting hungry now thinking about it!”

In Whanganui, Ben Potaka (Atihaunui-a-Paparangi, Ngāti Tuera, Ngāti Hinearo) says they too use methods that are hundreds of years old. “The only thing that’s changed is the materials.” Potaka is well known on the Whanganui river for his expertise on piharau, as well as tuna (eel), smelt, whitebait and pātiki. He comes from a family of fishermen, and learned how to fish for piharau from his grandfather.

“We have a distinct way of catching our fish,” he says, adding it’s hard to describe exactly how it works. “We build what we call an utu piharau. In the old days they used the kopuka logs, which is a type of mānuka; the kiekie root to make the hīnaki (eel pots) and they used harakeke and kareao to tie everything together.” Today they often use salvaged railway steel or corrugated iron, he says.

Like Taranaki iwi, they only grill their catch outside and everything must be shared. “Quite often the fishermen don’t get to eat any themselves.” Also like Taranaki, in Whanganui, the tikanga is that it’s solely the work of men. “Women don’t take part in any of it – making the hīnaki, building the utu piharau, even cooking them. Don’t ask me why! It’s just always been like that.”

Potaka is devoted to passing on the knowledge he has to the next generation, even if he gets “hōhā” when they don’t listen to him. “It’s a privilege not a right!” he chuckles. He also feels privileged that he gets to share mātauranga with people like Kitson and Tamarapa, whose paths cross regularly in sharing research and mātauranga on the species.

“We were fortunate enough to travel down to Murihiku with Jane down around Bluff, they’ve got a really good fishery, probably one of the strongest in the country. But the downside is they have that disease. That’s a worry aye. The concern we have in the North Island is, hopefully it will never get here but at some stage it might. We’re really worried. And until it gets here there’s nothing we can do.”

The disease he’s referring to is lamprey reddening syndrome, a mysterious affliction that appeared around 2011 and is characterised by haemorrhaging under the skin.

Kitson isn’t 100% sure it’s only confined to the Murihiku area – she thinks that because they have greater numbers of the species it might just be more apparent there. “There was quite a large mortality rate; they don’t heal up once the hemorrhaging starts. [There is] huge concern for whānau that it could be another factor in their demise when they’re already a threatened species.”

She says the kaitiaki that monitor the two freshwater mātaitai (customary gathering sites) at Mataura Falls and Waikawa do amazing work, but without more support they may not be able to protect the kanakana from the disease. “We had a mortality event at the end of last year when it was getting close to spawning times. No one was ready, really. It’s whānau that are caring for them and when they found out there wasn’t much they could do about it.”

They now have a strategy. The Ministry for Primary Industries and Department of Conservation have told whānau where to send any dead fish and how to store them. However, many communities are reporting that both the abundance and size of these freshwater taonga are declining. Like everything in our rivers, they are affected by pesticides and contaminants, loss of riparian vegetation, and barriers such as dams and weirs that cut them off from spawning sites.

“We’re starting to get a handle on where the habitats are, and that will help in the protection of them. We’re hoping by March next year we’ll have tools up on the Niwa website to help people learn how to find them, how to understand their habitat and how to protect them. ​​Also, the work that kaitiaki have done has led to DOC adding it as one of their migratory species work programmes.”

Tamarapa is also looking to the future and plans to get more agencies onboard with a strategy for measuring water quality and its impact on habitat for Waitara. “We may have the opportunity soon to develop a catchment plan. We have five iwi associated with that waterway – all their iwi entities will be involved, regional council, DOC, probably Ministry of Fisheries as well. Te Wai Māori will bring all those groups together when we do sit down to come up with that plan, and use piharau as the focus.”

They’re not a beautiful species like kākāpō or māui dolphins, but they have sustained communities for hundreds of years and been a conduit for the transfer of customary practices and mātauranga from each generation to the next. Perhaps the most fundamental lesson we can learn from the humble piharau is one we were taught at school – it’s what’s on the inside that counts.