Matauranga Māori and science saving taonga species

By Herewini Waikato

Te Arawa Lakes Trust Biodiversity Group and Te Roopu Raranga o Rotorua have combined their resources, knowledge, and experiences together with financial aid from Toitū Te Whenua Land Information New Zealand to create 'uwhi' - an underwater mat made of harakeke or flax that helps suppress pest weed and allows native vegetation to regrow for help taonga or native species, such as kākahi (Freshwater mussel) and koura (freshwater crayfish), flourish.

Te Arawa Lakes Trust biosecurity manager Wiremu Anaru says the problem with aquatic weeds is that they cause a problem for all taonga species and some of the areas they colonise.

“They can deoxygenate the water when they break down, they make muddy sediment, and kakahi and kōura don't like that sort of sediment.”

Turtles found in Rotorua lakes

Goldfish and weeds from aquariums tipped into the lakes over the years have caused the pest weed to grow and now the lakes are riddled with foreign species. “Things like turtles. We have seen tropical fish in drains over in Papamoa that are really big. And the weed came from those goldfish tanks,” Anaru says. 

Jim Schuster from Te Roopu Raranga o Rotorua is concerned about the food source and cultural impacts caused by this foreign weed. “If you go to any reefs around the lakes there are no freshwater crayfish because of this foreign weed.” 

The uwhi works by being spread out on the weed bed where the weed likes to grow. It blocks out the sun and the weeds can't grow. They slowly die and they rot away.

Underneath these mats, there is a native seed bank from native plants that have been there for centuries.

“The hope is these mats will allow these native plants to grow through and colonise those areas they couldn’t before,” Anaru says.

 Schuster spoke to Te Ao Mārama about his ancestors, who used uwhi as a walking mat on the water to get to resources in the swamps and to gather food. But “putting these underwater is something new”.

It took four weeks for Schuster and 20 weavers to produce all 12 uwhi which are 50 square metres each   

Kōura on Christmas table

Anaru and his team are monitoring see how many kōura are coming into these areas.

Schuster hopes he will see an influx of kōrua return to the shallows in time for him and his whānau to add this Ngāti Pikiao favorite kai to the Christmas table.

Anaru says, “This is a perfect example of combining matauranga Māori and western science”.