Tuna
Freshwater Eels
Anguilla dieffenbachii
Their Story
Tuna — the freshwater eels of Aotearoa — include the endemic longfin eel and the native shortfin eel. They are mysterious, long-lived creatures that spend most of their lives in shaded forest streams, only to journey to the sea to breed. Within the Brook Waimārama Sanctuary’s clean, shaded waterways, tuna are a quietly compelling indicator of stream health and forest-stream connection.
Conservation Status
At risk – declining
Eels are long-lived fish that spend some of their lives in freshwater and some of it in the ocean. They live in most of Aotearoa New Zealand’s rivers and lakes.
Populations are in decline due to habitat loss (dams, pollution, drainage), overfishing, and climate change, leading to their classification as At Risk, Declining.
Population
Populations of longfin eels across Aotearoa are declining. Shortfin eels have stable populations.
Changes to the environment, like pollution, sedimentation, climate change, diseases, overfishing and loss of habitat are all potential threats to native eels. Dams and weirs that stop eels moving up and downstream, also put significant pressure to their populations. Shortfin eels tend to be less vulnerable to these changes than longfins
Food
They feed opportunistically on insect larvae, small fish, freshwater crayfish (kōura), snails — and larger longfin eels may even prey on birds or ducklings.
The two main species are:
- Longfin eel (Anguilla dieffenbachii): endemic, with a dorsal fin that extends well forward of the anal fin, and loose skin that wrinkles when bent. They can grow over 1 m long, live for decades, and become very large. Wikipedia+1
- Shortfin eel (Anguilla australis): native(also found in Australia), with dorsal and anal fins of similar length and smoother skin when bent. Tend to be smaller and more coastal. Wikipedia+1
Tuna are largely nocturnal and spend much of their lives hidden under logs, rocks or in stream-bed crevices. They feed opportunistically on insect larvae, small fish, freshwater crayfish (kōura), snails — and larger longfin eels may even prey on birds or ducklings. Tuna elvers are incredible climbers, able to scale vertical waterfalls by clinging to wet moss and rocks. The adults are capable of moving around on land, especially during heavy rain. Source
Tuna are catadromous, adults migrate out to sea to spawn (probably the waters around Tonga for longfin), and die after releasing and fertilising millions of eggs. The larvae drift back, grow into elvers, and ascend deep into freshwater streams. Longfins can live 35-100+ years, maturing slowly; shortfin mature faster but still have long lives by fish standards. Science Learning Hub
Freshwater eels are found throughout New Zealand in rivers, lakes, wetlands, and forested creeks. The longfin eel is only found in Aotearoa; the shortfin also found in Australia. In the Brook Sanctuary, the continuous forests provide crystal clear streams that support abundant macroinvertebrates and an ideal habitat for these hidden taonga species. Earth Sciences New Zealand | NIWA
Longfin eels are classified At Risk – Declining in NZ, due primarily to the felling of native forests and the subsequent pollution of our waterways from farming and industry. Additionally, migration barriers (dams/weirs), overfishing, and changing climate threaten the persistence of this species. Earth Sciences New Zealand | NIWA+1 Shortfin eels are currently Not Threatened, but still vulnerable to habitat change. Their slow growth and epic migration make them sensitive indicators of river-ecosystem health.
At Brook Waimārama Sanctuary, the presence of tuna underscores the success of forest-stream restoration. Visitors wanting to see them need only look down into the streams, having a second glance at what at first looks like a stationary log. Their survival here points to the value of protecting mature forested catchments and clean water.
🎏 Some female longfin tuna can live more than 100 years, grow over 2 metres long, and travel hundreds of kilometres to the sea to breed.
Our other residents
Check out some of the other incredible wildlife that call the Sanctuary home
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Win prizes for your best summer photo at the Sanctuary 📸🏆☀️
This season, we want to see the Sanctuary through your lens — the bright light through the canopy, the textures of the forest floor, and the tiny details that make summer feel alive.
Enter our Summer Photography Competition (part of our Sanctuary Seasons series) and you could win:
🏆 Instant camera (Junior Photography winner)
🌙 Family ticket to a guided night tour
📰 Feature in our newsletter + social media
🖼️ Printed display at the Visitor Centre
📅 Entries close 28 February - Submit your entries via our website: Link in bio
Photo credit: Helen Power - Entry from the spring photography competition
#BrookWaimāramaSanctuary #SanctuarySeasons #Ngahere #NaturePhotography #NZWildlife #NelsonTasman #VisitNelson #NZHikes #EcoTourismNZ #ConservationStorytelling
Feb 4
Looking for a unique and memorable date night? 🌙🌲
This February, we’re introducing Date Me Darling — private, curated date nights inside the Sanctuary at dusk.
Three styled locations. One couple at a time. You’ll have a styled spot along the main loop track, locally sourced food and drinks, a few games to share, and time to slow down together as the forest shifts into evening.
Beech Glade: for when you want the world to fall away — deeply hidden, totally private, just you and the hush of the forest.
River: crystal clear water, canopy above, flickering lights — the kind of setup you usually only see on Instagram.
Meadow: open sky, long grass, and the forest standing quietly at the edges like it knows not to interrupt.
Bookings are open now (limited spaces in February only so don’t miss out!): Link in bio
#DateMeDarling #NelsonNZ #NelsonTasman #ThingsToDoNelson #DateNightIdeas #NatureLovers #SupportLocalNZ #ConservationNZ #BrookWaimāramaSanctuary
Feb 3
Two cute to be true?
Brook Waimārama Sanctuary and @savethekiwinz teams have been busy over the past few days tracking and recapturing kiwi to remove their transmitters. Thanks to a huge team effort, all ten males were recaptured within just three days.
Some nest burrows held a surprise or two — in several cases a female was present, and a couple even contained chicks. One burrow amazed us all, with not one but two adorable chicks 😍
All chicks are fully independent at this stage of the season, and after quick health checks and transmitter removal, all adult kiwi were safely returned to their burrows.
This special footage was captured by kiwi handler Tamsin from Save the Kiwi, who led the transmitter removal mahi.
We estimate the 20 females and 21 males released in May last year have already produced around 10–15 kiwi pukupuku (little spotted kiwi) chicks in their very first breeding season — a strong sign the habitat is just right.
With transmitters now removed from all ten males, the kiwi are completely free, with no further handling needed. Annual kiwi call counts by staff and volunteers will help track the growing population across our 690 ha, ring-fenced, pest-free sanctuary.
Credit: Video courtesy of Tamsin Ward-Smith, Save the Kiwi
Thanks to our partnership with @terunangaotoa Ngati Toa and Save the Kiwi
#kiwipukupuku #littlespottedkiwi #brookwaimaramasanctuary #nelson #thetopofthesouth #conservation #biodiversity #nativebirds #natureloversnz #newzealandwildlife #pestfree #ringfencedsanctuary #conservationinaction
Jan 29
🎻 45 min string quartet concert at Brook Waimārama Sanctuary
Come and hear a dynamic young string quartet perform a 45 min concert at Brook Waimārama Sanctuary. We welcome everyone to come along, and bring anyone you think might be curious to hear some classical music in a relaxed environment.
The @antipodes.quartet is part of the Fellowship Ensemble Programme, a joint venture between the @adamchambermusicfestival, @newzealandstringquartet and @chambermusicnz, as a career-development experience offered to four of this country’s most promising young string players.
The Antipodes Quartet are Eden Annesley (violin), Mana Waiariki (violin), Tal Amoore (viola) and Lavinnia Rae (cello).
On this occasion, Brook Waimārama Sanctuary are welcoming everyone at local prices: Adult $15, Child $9; Family $35 (on the door)
Find out more: (Link in bio)
#BrookWaimāramaSanctuary #NelsonNZ #Whakatū #WhatsonNelson #NelsonTasman #LiveMusicNZ #ChamberMusicNZ #StringQuartet #ClassicalMusicNZ #AdamChamberMusicFestival #NewZealandStringQuartet #ChamberMusicNewZealand #FamilyFriendly #NatureAndCulture #SupportLocalArts
Jan 27
2026 Bug of the year is here!
The lesser known cousin to bird of the year has come around(wait till they hear about fish or fungus of the year). This showdown aims to highlight the critters that go underappreciated compared to celebrity species like kākāpō. We would like to highlight the strange and wonderful species that occur within the Sanctuary, with the hopes to earn your vote!
Kahuwai | Black Tunnelweb Spider
Porrhothele antipodiana
I have a mixed history with this incredible spider. One hairy individual decided that my jersey pocket was a great place to set up shop. It received a rude awakening upon the home invasion of my unaware hand. Its brilliant fangs pierced and invenomated my finger, and despite the swelling and the shock and the pain… I couldn’t help but feel bad for evicting the guy. Its hobbit-like hole dwelling nature led the spider to my soft, warm pocket. Ironically, but not surprisingly, this species was the inspiration for Peter Jackson’s ‘Shelob’ in the Lord of the Rings films.
Kahuwai, the black tunnelweb spider, forms dense sheets of silk surrounding their tunnels. These sheets are monitored by the spider, who detects vibrations of a passer by. Wētā, land hoppers and any other unlucky invertebrate. The kahuwai swiftly grabs its prey and drags it into the depths. This spider however is also the victim of the endemic golden hunter wasp, who paralyses the spider before dragging it into the wasp’s nest (talk about shoes on the other foot!) and laying an egg beside it. The spider then becomes baby formula.
Despite the bite, this amazing spider has my vote! Check out the New Zealand Bug Of the Year 2026 website! Voting closes on the 16th of February!
Photo: @henry._.hart (in the second image of Shelob`s lair you can see a giant pill millipede has fallen victim...)
#BrookWaimāramaSanctuary #BugOfTheYear
Jan 25
2026 Bug of the year is here!
The lesser known cousin to bird of the year has come around(wait till they hear about fish or fungus of the year). This showdown aims to highlight the critters that go underappreciated compared to celebrity species like kākāpō. We would like to highlight the strange and wonderful species that occur within the Sanctuary, with the hopes to earn your vote!
This candidate is the beautifully disguised Rō, the Two-Spined Stick Insect. Micrachus hystriculeus is endemic to central Aotearoa, most common from Nelson, through Marlborough and Wellington. Stick insects display a classic example of crypsis. That is, their behaviour and physiology work in tandem to remain completely undetected and unharmed. They feed on leaves high in the canopy of trees like kānuka. At night you can often spot them, usually with the small males riding on the backs of the much larger females.
All modern New Zealand stick insects are the relatives of two colonisation events from New Caledonia around 30 million years ago. They radiated into nine separate genera and dispersed into coastal, lowland and subalpine ecosystems throughout the motu. This species, alongside at least five other stick insect species, live out their slow and sticky lives within the Brook Waimārama Sanctuary.
Will you vote for Micrachus hystriculeus? Check out the New Zealand Bug Of the Year 2026 website! Voting closes on the 16th of February!
Stay tuned for our last candidate…
Photo: Saryu Mae - @invertebratist
#BrookWaimāramaSanctuary #BugOfTheYear
Jan 24
