Partnering Indigenous Knowledge Systems And Western Science To Help Freshwater Thrive

A traditional mātauranga Māori method has been used successfully to collect freshwater fish in the latest translocation at Zealandia Te Māra a Tāne.

One hundred and thirty-nine toitoi/common bully (Gobiomorphus cotidianus) were collected from Kohangapiripiri in the Parangarahu Lakes area in late April and early May.

Whakaweku, a traditional Māori catching method made from bundles of rārahu/bracken fern, was successfully trialled as one of the collection methods.

Zealandia and mana whenua partners Taranaki Whānui ki te Ūpoko o te Ika have begun releasing the fish at the Wellington ecosanctuary after a period of quarantine.

Toitoi are one of the most common freshwater fish species in Aotearoa New Zealand. However, prior to 2023, they had been completely lost from Zealandia Te Māra a Tāne, a problem common across Aotearoa New Zealand. Poor water quality, habitat loss and introduced species are taking their toll on our unique species and ecosystems.

This project, in partnership with Taranaki Whānui ki te Ūpoko o te Ika, is part of a freshwater focus for Zealandia Te Māra a Tāne. The Kaiwharawhara catchment begins in Zealandia, and is home to thousands of animals, insects, and plants as well as 39,000 people. The sanctuary is on a 500-year journey to create a corner of the world where New Zealand’s unique animals and plants can thrive in healthy, vibrant ecosystems—not just in the forests, but beneath the surface of the waters as well.

Toitoi were strategically selected to move to the sanctuary as they carry out an important job within the freshwater ecosystem.

“Diversity within an ecosystem is vital as each species plays a unique role and makes it more resilient and healthier. Toitoi are an important species for freshwater as they aid with the reproductive cycle of kākahi, the freshwater mussel,” said Jo Ledington, General Manager of Conservation and Restoration at Zealandia.

Last year Zealandia and Rōpū Tiaki (the co-management group for Parangarahu Lakes consisting of Taranaki Whānui and Greater Wellington Regional Council representatives) worked together to collect and release 160 toitoi into Zealandia. This was likely the first freshwater fish translocation done within Aotearoa New Zealand solely for restoration reasons. The focus of the 2024 translocation was to help secure the newly establishing population in Zealandia and to trial using whakaweku, led by kaimahi Māori (Māori staff).

Whakaweku are bundles of rārahu/bracken fern which are submerged into water for a few weeks. While in the water the bundles act as habitat for bottom-dwelling ika/fish, insects and kōura/crayfish which move into these bundles. Because the ika/fish choose to move into the whakaweku themselves and can come and go before collection, it is a gentle and less stressful method of catching them. While traditionally whakaweku has been used to capture kōura/crayfish, studies have shown that whakaweku can be effective for sampling and collecting small-bodied bottom-dwelling fish such as bullies.

Zealandia has a focus on utilising both western science and indigenous knowledge systems in conservation work. Drawing on mātauranga Māori in this project allowed Māori staff and others involved to strengthen their connections with each other and with the natural world, all of which are especially important in a world of climate and biodiversity crisis.

“Embracing whakaweku in this way created rich kōrero about traditional and contemporary translocation methods, natural vs people-made materials, and pros and cons to different methods. It is a conscious commitment to actively continue to learn, increase and include mātauranga Māori in modern day conservation practice, and continue to dismantle generations of colonial impact of suppression and dominance at the expense of indigenous expertise,” shared Terese McLeod (Taranaki Whānui), Bicultural Lead Ranger at Zealandia.

Kaitiaki Rangers at Zealandia and freshwater ecologists from NIWA tested the whakaweku throughout the Kaiwharawhara catchment in the weeks leading up to the translocation to practice using the method and also to see how freshwater species would interact with them.

Freshwater ecologist from NIWA Mark Fenwick, who has Taranaki Whānui whakapapa, was nervous at first about using whakaweku.

“Although Te Arawa Lakes Trust has had great success with kōura, targeting toitoi was new and untested. We were thrilled, and relieved, that they were successful. I think we all felt the weight of responsibility in bringing mātauranga Māori methods into a modern construct. Whakaweku are relatively easy to use and cheap to make, so they are an ideal tool for iwi and hapu and community groups to use.”

Whakaweku had also never been used in a Greater Wellington Regional Park before.

“We are proud to see mātauranga Māori approaches to conservation being used to preserve the mauri (life force) of our native species,” said Lee Hunter of Taranaki Whānui and Rōpū Tiaki co-chair.

“Translocating toitoi from Lake Kohanga Piripiri, one of the most pristine coastal freshwater lakes in Aotearoa, is a testament to the health of the wai – health that is now spreading across the region to restore freshwater ecosystems.

“Zealandia has approached this kaupapa with the utmost respect for Taranaki Whānui, and it is always a pleasure working alongside those who share our long-term visions for this rohe. For whānau, it’s about the continued relationship between ngā uri o Ranginui me Papatūanuku."

There is one more translocation of toitoi into Zealandia waters planned to take place in 2025.

This project is part of Kia Mouriora te Kaiwharawhara Sanctuary to Sea, which is a collaborative initiative with a 100-year vision to restore the mouri/life force of the Kaiwharawhara water catchment. This translocation will help to create richer and more interconnected ecosystems beginning at the headwaters of the catchment within the sanctuary and filtering down throughout the catchment.

Notes:

• Toitoi are one of the most common freshwater fish species in Aotearoa New Zealand. This small fish species reaches about 50-60mm in lake populations (though individuals can be up to 120mm outside of lakes), are typically dark grey to brown in colour and live for around 1-4 years.
• Toitoi are an important species to have at Zealandia Te Māra a Tāne because of their relationship with kākahi, the freshwater mussel. Kākahi use toitoi as ‘public transport’, shuttling their offspring to a different part of their freshwater home. Adult kākahi ‘sneeze’ their larvae (glochidia) into the water, which then attach onto the gills or fins of a nearby fish (preferably toitoi) to catch a ride away from their parents. Along the way, toitoi provide the right environment, signals and conditions for glochidia to undergo metamorphosis. Research has shown that very few glochidia transform into juvenile kākahi when attached to non-native fish species. Native species such as the toitoi show the highest rate of glochidia transformation. While hooked on the fish they transform from larvae into their mussel form, then they drop off from the fish.
• At home you can help freshwater plants and animals by thinking about what products you put down your drain, planting up your backyard to reduce water entering drains, and being careful with the amount of water you use. Consider installing rainwater tanks to reduce pressure on the stormwater system and provide a water source for your garden and emergency water supply. These actions don’t only help our local waterways but also provide resilience against climate events and water shortages.

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