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
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🪶 Ngahere Neighbourhood: piriwai (spiny gilled mayfly)
Tiny, ancient, and found only in Aotearoa — the spiny gilled mayfly (Coloburiscus humeralis) spends up to four years underwater before living just a few days as an adult.
Piriwai can only survive in clean, fast-flowing streams. Its larvae cling to river rocks, filtering food from the water with tiny hair-like gills. They are an important sign of healthy freshwater ecosystems, so much so that this species gets a rating of 8-9 on the sensitivity/stream health rating. All native stream macroinvertebrates are ranked in terms of their sensitivity and used as a bioindicator of stream health.
The Sanctuary stream is a reference site for stream health and represents a `pure`, unadulterated site and thus is highly diverse in sensitive stream invertebrates.
📸 Photo: Taken by Henry Hart here at the Sanctuary
#NgahereNeighbourhood #BrookSanctuary #AotearoaNature #FreshwaterLife #NelsonTasman #Conservation #Piriwai
Feb 17
Their Raucous Call Returns: Kākā Set to Reclaim the Brook Waimārama Sanctuary. 🦜
This March, we’re scheduled to welcome two male and one female kākā fledglings from the Dunedin Botanic Garden kākā breeding programme. There’s also the potential for a further four birds to arrive in May.
Kākā are unique to Aotearoa and are nationally vulnerable, with populations heavily impacted by introduced predators. Releasing them into a pest-free sanctuary with ideal habitat (old growth beech forest) gives them the best chance to thrive.
This release will build on years of species translocations as part of the Sanctuary’s ambitious ecosystem restoration efforts, including:
🏠 Kākāriki karaka in 2021
🏠 Powelliphanta hochstetteri consobrina (giant snails) in 2021
🏠 Tuatara in November 2024 and May 2025
🏠 Kiwi in May 2025
Over the coming weeks, our team will be busy planning and preparing for this important translocation. We’ll share more details on timing and what to expect closer to the date.
Thank you to our community of donors, volunteers, business supporters, and Sanctuary Members for continuing to back the Sanctuary — your support is vital to every species return. We can’t wait to celebrate this next milestone with you.
#BrookWaimāramaSanctuary #Kākā #ConservationNZ #NelsonNZ #PredatorFree #NativeWildlife #Biodiversity
Feb 10
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
